JP2022182557A - Vehicle braking control device - Google Patents

Abstract

To provide a braking control device whose power source is an electric motor, capable of avoiding the electric motor stalling.SOLUTION: A braking control device comprises a pressurizing unit that allows a pressure regulating valve to regulate pressure of brake fluid discharged by a fluid pump driven by an electric motor, and a controller that regulates brake fluid pressure of a wheel cylinder by controlling the pressurizing unit. The controller limits a current value to the pressure regulating valve on the basis of a load state quantity indicating a degree of a load of the electric motor. Specifically, the controller does not execute the limitation when the load state quantity is less than a predetermined quantity, and executes the limitation when the load state quantity is equal to or more than the predetermined quantity.SELECTED DRAWING: Figure 4

Description

The present disclosure relates to a vehicle braking control device.

Patent Document 1 discloses that the device is a "brake control device capable of controlling wheel cylinder pressure ( 3, 9) are a pump (6) capable of sucking hydraulic fluid and discharging it to a fluid passage (31) connected to the wheel cylinder (21), and an electric motor (60) for driving the pump (6). When the hydraulic pressure on the discharge side of the pump (6) is higher than a predetermined first hydraulic pressure, the duty ratio is set to 100% and the motor (60) is controlled by PWM control. and an electronic control unit (9) configured to continuously drive the .

By the way, the applicant has developed a braking control device as described in Patent Documents 2 and 3. Specifically, in the brake control device, the brake fluid discharged by the fluid pump driven by the electric motor is throttled by an electromagnetic valve (pressure regulating valve) to adjust the hydraulic pressure of the wheel cylinder (brake fluid pressure). be. Here, the maximum output of the electric motor is designed so as to be able to achieve the maximum value of the brake hydraulic pressure (ie the maximum hydraulic pressure that can be adjusted by the pressure regulating valve). However, a situation may arise in which the electric motor stalls due to a decrease in the output of the electric motor or the occurrence of an excessive load. In particular, in the brake-by-wire type braking control device, the electric motor is used as a power source, and therefore it becomes difficult to appropriately adjust the brake fluid pressure due to the stall of the electric motor. Therefore, a braking control device that can avoid stalling of the electric motor is desired.

JP 2020-019335 A JP 2019-059458 A JP 2019-137202 A

SUMMARY OF THE INVENTION An object of the present invention is to provide a braking control device for a vehicle using an electric motor as a power source, which can avoid stalling of the electric motor.

A braking control device for a vehicle according to the present invention regulates the pressure (Pa, Pb) of a braking fluid (BF) discharged by a fluid pump (QA) driven by an electric motor (MA) by means of pressure regulating valves (UA, UB). and a controller (ECU) that adjusts the braking fluid pressure (Pw) of the wheel cylinder (CW) by controlling the pressurizing unit (KU).

In the vehicle braking control apparatus according to the present invention, the controller (ECU) controls the pressure regulating valves (UA, UB) based on a load state quantity (Jm) representing the degree of load on the electric motor (MA). Limit the current values (Ia, Ib). For example, the controller (ECU) does not execute the restriction when the load state quantity (Jm) is less than a predetermined quantity (jm), and when the load state quantity (Jm) is greater than or equal to the predetermined quantity (jm). enforce the above restrictions.

In the vehicle braking control device according to the present invention, the controller (ECU) controls current values (Ia, Ib) to the pressure regulating valves (UA, UB) based on the power supply voltage (Vm) of the electric motor (MA). restrictions. For example, the controller (ECU) does not execute the restriction when the power supply voltage (Vm) is equal to or higher than a predetermined voltage (vm), and when the power supply voltage (Vm) is less than the predetermined voltage (vm) enforces the above restrictions.

Stalling of the electric motor is likely to occur when the load state quantity of the electric motor is excessive or when the power supply voltage of the electric motor is low. According to the above configuration, in a braking control device using an electric motor as a power source, when the probability of motor stall is high, the current value of the pressure regulating valve is limited, so that the stall can be prevented.

1 is a schematic diagram for explaining an entire vehicle provided with a vehicle braking control device SC according to the present invention; FIG. FIG. 4 is a schematic diagram for explaining a first configuration example of the fluid unit HU; FIG. 5 is a flow chart for explaining a first processing example of pressure regulation control; FIG. 10 is a characteristic diagram for explaining energization limitation of the pressure regulating valve UA; FIG. 11 is a flowchart for explaining a second processing example of pressure regulation control; FIG. 4 is a schematic diagram for explaining a second configuration example of the fluid unit HU;

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

<Symbols of constituent elements, etc.>
In the following description, constituent elements such as members, signals, values, etc. denoted by the same reference numerals such as "CW" have the same function. The suffixes "f" and "r" attached to the end of various symbols related to wheels are generic symbols indicating whether the elements relate to the front wheels or the rear wheels. Specifically, "f" indicates an element related to the front wheels, and "r" indicates an element related to the rear wheels. For example, the wheel cylinders CW are described as "front wheel cylinder CWf, rear wheel cylinder CWr". Additionally, the subscripts "f" and "r" may be omitted. When these are omitted, each symbol represents its generic name.

<Vehicle JV equipped with braking control device SC>
An overall configuration of a vehicle JV equipped with a braking control device SC will be described with reference to the schematic diagram of FIG. Here, the vehicle equipped with the braking control device SC is also referred to as "own vehicle JV" in order to distinguish it from other vehicles (for example, preceding vehicle SV).

The vehicle JV is a hybrid vehicle or an electric vehicle having an electric motor GN for driving. The electric motor GN for driving also functions as a generator for regenerating energy. For example, the generator GN is provided for the front wheels WHf. The generator GN is controlled (driven) by a generator controller EG. Here, a device including the generator GN and its controller EG is called a "regenerative braking device KC". The vehicle JV is provided with a storage battery BT (also referred to as a "running storage battery") for the regenerative braking device KC. That is, the regenerative braking device KC also includes the running storage battery BT.

When the electric motor/generator GN operates as an electric motor for driving (for example, during acceleration of the vehicle JV), the storage battery BT provides power to the electric motor/generator GN. On the other hand, when the electric motor/generator GN operates as a generator (during deceleration of the vehicle JV), electric power from the generator GN is stored in the storage battery BT via the regenerative controller EG (so-called regenerative braking is performed). is called). In regenerative braking, a regenerative braking force Fg is generated by the front wheel generator GN.

The vehicle JV is provided with a braking device SX. Front and rear wheel frictional braking forces Fmf and Fmr are generated on the front wheels WHf and the rear wheels WHr by the braking device SX. The braking device SX includes a rotating member (for example, brake disc) KT and a brake caliper CP. The rotating member KT is fixed to the wheel WH, and a brake caliper CP is provided so as to sandwich the rotating member KT. A wheel cylinder CW is provided in the brake caliper CP. A braking fluid BF adjusted to a braking fluid pressure Pw is supplied to the wheel cylinder CW from the braking control device SC. The braking fluid pressure Pw presses the friction member (for example, brake pad) MS against the rotating member KT. Since the rotary member KT and the wheels WH are fixed so as to rotate integrally, friction braking force Fm is generated on the wheels WH by the frictional force generated at this time.

The vehicle JV is equipped with a braking operation member BP and various sensors (BA, etc.). A braking operation member (for example, a brake pedal) BP is a member operated by the driver to decelerate the vehicle. The vehicle JV is provided with a braking operation amount sensor BA that detects an operation amount (braking operation amount) Ba of the braking operation member BP. As the braking operation amount sensor BA, an input hydraulic pressure sensor PN for detecting a hydraulic pressure Pn (hereinafter referred to as "input hydraulic pressure") in an input chamber Rn (described later), an operation displacement sensor SP for detecting an operation displacement Sp of the braking operation member BP, And at least one of the operating force sensors FP for detecting the operating force Fp of the brake operating member BP is employed. That is, the operation amount sensor BA detects at least one of the input hydraulic pressure Pn, the braking operation displacement Sp, and the braking operation force Fp as the braking operation amount Ba. The braking operation amount Ba is input to a controller ECU for the braking control device SC (simply referred to as a "braking controller"). The vehicle JV is equipped with various sensors including a wheel speed sensor VW for detecting the rotational speed (wheel speed) Vw of the wheels WH. Detection signals (Ba, Vw, etc.) of these sensors are input to the braking controller ECU. The braking controller ECU calculates a vehicle body speed Vx based on the wheel speed Vw.

The vehicle JV is provided with a braking control device SC so that so-called regenerative cooperative control (control for cooperatively operating the regenerative braking force Fg and the frictional braking force Fm) is executed. For example, a brake-by-wire type is adopted as the braking control device SC. The brake control device SC adjusts the actual brake fluid pressure Pw according to the operation amount Ba of the brake operation member BP. The braking control device SC supplies braking fluid pressure Pw to the braking device SX (in particular, the wheel cylinder CW) via the front wheel/rear wheel connecting passages HSf and HSr.

The braking control device SC is composed of a hydraulic unit HU (also referred to as an "actuator") including a master cylinder CM, and a controller ECU (brake controller) for the braking control device SC. A fluid unit HU (described later) is controlled by a braking controller ECU. A controller ECU for the braking control device SC is composed of a microprocessor MP for signal processing, and a drive circuit DD for driving the solenoid valves and the electric motor.

The vehicle JV is provided with a driving support device UC that performs automatic braking instead of or to assist the driver. The driving assistance device UC includes an object detection sensor OB for detecting a distance Ds (relative distance) to an object OJ in front of the own vehicle JV (including a preceding vehicle SV traveling in front of the own vehicle JV), and a driving assistance device. It is composed of a controller ECA for For example, a radar sensor, a millimeter wave sensor, an image sensor, etc. are employed as the object detection sensor OB. The driving assistance controller ECA calculates a target deceleration Gd of the own vehicle JV (a target value of vehicle body acceleration in the longitudinal direction of the own vehicle JV) based on the detection result Ds (relative distance) of the object detection sensor OB. The target deceleration (target vehicle longitudinal acceleration) Gd is transmitted from the driving assistance controller ECA to the braking controller ECU via the communication bus BS. Braking forces Fg and Fm corresponding to the target deceleration Gd are generated by the braking control device SC.

The braking controller ECU, the controller EG for the regenerative braking device, and the controller ECA for the driving support device are each connected to the communication bus BS. Therefore, information (detected values, calculated values) is shared between these controllers via the communication bus BS. For example, the vehicle body speed Vx is calculated by the braking controller ECU and transmitted to the controller ECA for the driving assistance device (simply referred to as "driving assistance controller") through the communication bus BS. A target deceleration Gd is calculated by the driving assistance controller ECA and transmitted to the braking controller ECU via the communication bus BS. A braking operation amount Ba, a wheel speed Vw, a target deceleration Gd, and the like are input to the braking controller ECU. Based on these signals, the brake controller ECU controls the hydraulic unit HU. Here, since the braking operation amount Ba and the target deceleration Gd are required values for decelerating the vehicle JV, they are collectively referred to as "deceleration required value Bs". The braking controller ECU and the driving assistance controller ECA are supplied with power from a storage battery BU (referred to as an "auxiliary equipment storage battery") that is separate from the running storage battery BT.

<First Configuration Example of Fluid Unit HU>
A first configuration example of the fluid unit HU will be described with reference to the schematic diagram of FIG. The fluid unit HU is a pressurization source for increasing and adjusting the hydraulic pressure (braking hydraulic pressure) Pw of the four wheel cylinders CW. In the example, the fluid unit HU is integrated with a single-type master cylinder CM. A front/rear type (also referred to as "II type") type is adopted as a braking system. The fluid unit HU is composed of an apply unit AU (including the master cylinder CM) and a pressure unit KU. The fluid unit HU and wheel cylinder CW are connected by a communication path HS, an input path HN, a reservoir path HR, a return path HK, and a servo path HV. These are fluid paths through which the damping fluid BF is moved, and correspond to fluid pipes, fluid paths in the fluid unit HU, hoses, and the like. The apply unit AU and pressurization unit KU are controlled by the braking controller ECU.

≪Apply unit AU≫
The apply unit AU includes a master reservoir RV, a master cylinder CM, a master piston NM, a master spring DM, an input cylinder CN, an input piston NN, an input spring DN, an input valve VN, a release valve VR, a stroke simulator SS, and an input hydraulic pressure. It is composed of the sensor PN. The apply unit AU is provided with various hydraulic chambers such as an input chamber Rn, a servo chamber Ru, a rear chamber Ro, and a master chamber Rm. Here, the "hydraulic chamber" is a chamber filled with the damping fluid BF and sealed by the seal member SL. The volume of each hydraulic chamber is changed by movement of the input piston NN and master piston NM.

The master reservoir (also called "atmospheric pressure reservoir") RV is a tank for the hydraulic fluid, in which the brake fluid BF is stored. The master reservoir RV is connected to the master cylinder CM (especially the master chamber Rm).

The master cylinder CM is a cylinder member having a bottom. A master piston NM is inserted inside the master cylinder CM, and the inside thereof is sealed by a seal member SL to form a master chamber Rm. The master cylinder CM is a so-called single type. The master chamber Rm is finally connected to the front wheel cylinder CWf via the front wheel communication passage HSf and the hydraulic pressure modulator MJ. When the master piston NM is moved in the forward direction Ha (the direction in which the volume of the master chamber Rm decreases), the hydraulic pressure modulator MJ (finally, the front wheel cylinder CWf) from the fluid unit HU (especially the master cylinder CM) is supplied with the braking fluid BF at a fluid pressure Pm (referred to as "supply fluid pressure").

A flange portion (flange) Tp is provided on the master piston NM. The interior of the master cylinder CM is further partitioned into a servo chamber Ru and a rear chamber Ro by the flange Tp. The servo chamber Ru is arranged to face the master chamber Rm with the master piston NM therebetween. Further, the rear chamber Ro is sandwiched between the master chamber Rm and the servo chamber Ru and arranged therebetween. The servo chamber Ru and the rear chamber Ro are also sealed by the seal member SL in the same manner as described above.

For example, the pressure receiving area of the flange Tp (that is, the pressure receiving area of the servo chamber Ru) ru is set equal to the pressure receiving area of the master piston NM (that is, the pressure receiving area of the master chamber Rm) rm. In this case, the hydraulic pressure Pa (described later) introduced into the servo chamber Ru and the supplied hydraulic pressure Pm are the same in the steady state (that is, since "ru=rm", "Pa=Pm" be).

Input cylinder CN is fixed to master cylinder CM. An input piston NN is inserted inside the input cylinder CN and sealed by a seal member SL to form an input chamber Rn. The input piston NN is mechanically connected to the brake operating member BP via a clevis (U-shaped link). The input piston NN is provided with a flange portion (flange) Tn. An input spring DN is provided between the mounting surface of the input cylinder CN to the master cylinder CM and the flange portion Tn of the input piston NN. The input spring DN presses the flange Tn against the bottom of the input cylinder CN along the central axis of the master cylinder CM.

During non-braking, inside the input cylinder CN, there is a gap Ks (also referred to as "separation distance") between the master piston NM (especially the end face Mp) and the input piston NN (especially the end face Mn). When the brake is not applied, the pistons NM and NN are located at the position closest to the retreat direction Hb (referred to as the "initial position" of each piston). The gap Ks in this situation is referred to as "predetermined distance ks (also referred to as "initial gap")". Since the master piston NM and the input piston NN are separated by the distance Ks in the input chamber Rn, a situation is created in which the braking hydraulic pressure Pw is not generated even though the braking operation member BP is being operated. . That is, the separation distance Ks enables execution of regenerative cooperative control. The separation distance Ks is controlled (adjusted) by a servo hydraulic pressure Pa (described later).

The input chamber Rn and the rear chamber Ro are connected via an input path HN. An input valve VN is provided in the input path HN. The input line HN is connected to the master reservoir RV between the rear chamber Ro and the input valve VN via the open valve VR and the reservoir line. The input valve VN and the release valve VR are two-position solenoid valves (also called "on/off valves") having an open position (communication state) and a closed position (blockage state). A normally closed solenoid valve is employed as the input valve VN. A normally open solenoid valve is employed as the open valve VR.

A stroke simulator (simply referred to as “simulator”) SS is connected to the rear chamber Ro. The simulator SS generates an operating force Fp for the brake operating member BP. A piston and an elastic body (for example, a compression spring) are provided inside the simulator SS. When the brake fluid BF flows into the simulator SS, the piston is pushed by the brake fluid BF. Since a force is applied to the piston by the elastic body in a direction to prevent the inflow of the brake fluid BF, an operating force Fp is generated for the brake operating member BP. In other words, the operating characteristics of the brake operating member BP (the relationship between the operating displacement Sp and the operating force Fp) are formed by the simulator SS.

An input hydraulic pressure sensor PN is provided to detect the hydraulic pressure Pn (referred to as "input hydraulic pressure") in the input chamber Rn. The input hydraulic pressure Pn is also the hydraulic pressure of the simulator SS and the rear chamber Ro. The input hydraulic pressure sensor PN is one of the braking operation amount sensors BA described above, and the input hydraulic pressure Pn is input to the braking controller ECU as the braking operation amount Ba.

In addition to the input hydraulic pressure sensor PN, the hydraulic unit HU includes, as a braking operation amount sensor BA, an operation displacement sensor SP for detecting an operation displacement Sp of the braking operation member BP and/or an operation force Fp of the braking operation member BP. An operating force sensor FP is provided to detect the . That is, at least one of the input hydraulic pressure sensor PN, the operation displacement sensor SP (stroke sensor), and the operation force sensor FP is employed as the braking operation amount sensor BA. Therefore, the braking operation amount Ba is at least one of the input hydraulic pressure Pn, the operation displacement Sp, and the operation force Fp.

≪Pressurization unit KU≫
The pressurizing unit KU is composed of an electric motor MA, a fluid pump QA, a pressure regulating valve UA, a supply hydraulic pressure sensor PM, and a servo hydraulic pressure sensor PA. In the pressure unit KU, the pressure of the brake fluid BF discharged by the fluid pump QA driven by the electric motor MA is adjusted by the pressure regulating valve UA. Here, the hydraulic pressure adjusted by the pressure regulating valve UA is referred to as "servo hydraulic pressure Pa". The servo hydraulic pressure Pa is supplied to the apply unit AU (in particular, the servo chamber Ru) and the rear wheel wheel cylinder CWr, and finally front and rear wheel braking hydraulic pressures Pwf and Pwr (=Pw) are generated. be.

A combination of "one electric motor MA" and "one fluid pump QA driven by the electric motor MA" constitutes an electric pump. The electric motor MA is a power source for generating and adjusting the hydraulic pressure (braking hydraulic pressure) Pw of the wheel cylinder CW during braking. The electric motor MA is provided with a motor rotation speed sensor NS to detect the rotation speed Ns of the electric motor MA. A rotation angle sensor (not shown) may also be provided to detect the rotation angle Ka of the electric motor MA. In this case, the motor rotation speed Ns is calculated by time-differentiating the motor rotation angle Ka.

In the fluid pump QA, the suction portion Qs and the discharge portion Qt are connected via the return path HK. A suction portion Qs of the fluid pump QA is connected to the master reservoir RV via a reservoir passage HR. When the electric motor MA is driven and the fluid pump QA is rotated, the brake fluid BF circulates through the return path HK. Further, when the amount of the brake fluid BF is insufficient in the return passage HK, the apply unit AU, the wheel cylinder CW, etc., the brake fluid BF is sucked from the master reservoir RV via the reservoir passage HR. A check valve is arranged in the return path HK so that the fluid pump QA is not reversed.

A pressure regulating valve UA is provided in the return path HK so as to adjust the pressure Pa (servo hydraulic pressure) of the braking fluid BF discharged by the fluid pump QA. The pressure regulating valve UA is a linear solenoid valve (also referred to as a “proportional valve” or “differential pressure valve” whose valve opening amount (lift amount) is continuously controlled according to its energized state (for example, supply current). ). A normally open solenoid valve is employed as the pressure regulating valve UA.

When the electric motor MA is in operation, the circulation flow KN (fluid flow) of the braking fluid BF returns to the original flow as indicated by the dashed arrow in the circulation path HK. ”) is generated. The return KN is throttled by the pressure regulating valve UA (so-called orifice effect), thereby regulating the servo hydraulic pressure Pa (the pressure between the discharge port Qt of the fluid pump QA and the pressure regulating valve UA). Since the pressure regulating valve UA is of a normally open type, it is fully open when not energized, and the servo hydraulic pressure Pa is "0".

The return path HK is connected to the servo chamber Ru via the servo path HV between the discharge portion Qt and the pressure regulating valve UA. Therefore, the servo hydraulic pressure Pa is supplied to the servo chamber Ru. In a configuration in which the pressure receiving area ru of the servo chamber Ru and the pressure receiving area rm of the master chamber Rm are equal, when the servo hydraulic pressure Pa is supplied to the servo chamber Ru, a pressure equal to the servo hydraulic pressure Pa is supplied from the master chamber Rm. A certain supply fluid pressure Pm is output (that is, "Pm=Pa"). Furthermore, even if the pressure-receiving areas ru and rm are different, the relationship between them (for example, the ratio of the pressure-receiving areas) is known, so the supply hydraulic pressure Pm and the servo hydraulic pressure Pa can be interconverted.

A master chamber Rm of the master cylinder CM is connected to a front wheel cylinder CWf via a front wheel communication path HSf and a hydraulic pressure modulator MJ. The hydraulic pressure modulator MJ is for adjusting the hydraulic pressure Pw of each wheel cylinder CW independently and individually in antilock brake control, vehicle stability control, and the like. The front wheel communication passage HSf is branched into two within the hydraulic modulator MJ. The branched front wheel communication path HSf is connected to each of the front wheel cylinders CWf. A supply fluid pressure sensor PM is provided in the front wheel communication passage HSf so as to detect the fluid pressure Pm of the brake fluid BF supplied from the master chamber Rm. For example, supply hydraulic pressure sensor PM is contained within hydraulic modulator MJ. Here, when the hydraulic pressure modulator MJ is not operated, the supplied hydraulic pressure Pm is equal to the hydraulic pressure (front wheel brake hydraulic pressure) Pwf in the front wheel cylinder CWf.

In the adjustment (for example, pressurization) of the front wheel braking hydraulic pressure Pwf, the servo hydraulic pressure Pa is transmitted via the master cylinder CM in the order of "Ru→Rm→CWf". On the other hand, adjustment (for example, pressurization) of the rear wheel braking hydraulic pressure Pwr is performed by directly supplying the servo hydraulic pressure Pa to the rear wheel wheel cylinder CWr. Specifically, the rear wheel communication passage HSr is connected to the return passage HK between the discharge portion Qt and the pressure regulating valve UA. Further, the rear wheel communication path HSr is branched into two within the hydraulic pressure modulator MJ and connected to each of the rear wheel cylinders CWr. A servo hydraulic pressure sensor PA is provided in the rear wheel connecting passage HSr so as to detect the servo hydraulic pressure Pa. When the apply unit AU is configured with "ru=rm", there is a time lag between the servo hydraulic pressure Pa and the supply hydraulic pressure Pm, but substantially (steady) are equal, one of the servo hydraulic pressure sensor PA and the supply hydraulic pressure sensor PM may be omitted. Similarly to the above, when the hydraulic pressure modulator MJ is not operated, the servo hydraulic pressure Pa is equal to the hydraulic pressure (rear wheel braking hydraulic pressure) Pwr in the rear wheel wheel cylinder CWr.

<<Drive of fluid unit HU by braking controller ECU>>
A signal of a deceleration request value Bs (generic term for braking operation amount Ba and target deceleration Gd) is input to the braking controller ECU. Here, the braking operation amount Ba is a signal indicating the degree of operation of the braking operation member BP, and is at least one of the input hydraulic pressure Pn, the operation displacement Sp, and the operation force Fp. Signals (such as Pa) from various sensors (such as PA) provided in the fluid unit HU are input to the controller ECU. Based on these signals and a control algorithm programmed in the microprocessor MP provided in the controller ECU, the drive signal Vn for the input valve VN, the drive signal Vr for the open valve VR, the drive signal Ua for the pressure regulating valve UA, and the , the drive signal Ma of the electric motor MA is calculated. Electric power is supplied to the controller ECU from the storage battery BU. Based on this power supply, the solenoid valves "VN, VR, UA" and the electric motor MA that constitute the fluid unit HU are controlled (driven) according to the drive signals "Vn, Vr, Ua, Ma". .

Specifically, the brake controller ECU is provided with a drive circuit DD to drive the solenoid valves "VN, VR, UA" and the electric motor MA. Electric power is supplied to the drive circuit DD from the auxiliary equipment storage battery BU. A bridge circuit is formed in the drive circuit DD by switching elements (power semiconductor devices such as MOS-FETs and IGBTs) so as to drive the electric motor MA. Based on the motor drive signal Ma, the energization state of each switching element is controlled, and the output of the electric motor MA is controlled. In the drive circuit DD, the energized state (that is, the excited state) is controlled based on the drive signals "Vn, Vr, Ua" so as to drive the solenoid valves "VN, VR, UA".

The drive circuit DD is provided with a voltage sensor VM so as to detect a supply voltage value Vm (also referred to as "power supply voltage") from the auxiliary equipment storage battery BU (power supply). Further, the drive circuit DD is provided with a current sensor ID for detecting actual current values Id of the electric motor MA and the solenoid valves "VN, VR, UA". Note that the current sensor ID is a generic term for a plurality of current sensors. Specifically, the current sensor ID includes a motor current sensor IM for detecting the current value Im of the electric motor MA (motor current value), and a pressure regulator current sensor IM for detecting the current value Ia of the pressure regulator valve UA (regulator valve current value). Sensor IA etc. are included.

The drive circuit DD is provided with a circuit temperature sensor TD to detect the temperature Td of the drive circuit DD (in particular, the switching element). The electric motor MA is also provided with a motor temperature sensor TM to detect the temperature Tm of the electric motor MA. The circuit temperature Td and the motor temperature Tm are used for determination based on the load state quantity Jm (described later).

During braking when the brake operation member BP is operated, the input valve VN is opened and the release valve VR is closed. Accordingly, the brake fluid BF discharged from the input chamber Rn is moved to the simulator SS in conjunction with the movement of the brake operating member BP. Thereby, the operating force Fp of the brake operating member BP is generated. Also, during braking, the electric motor MA and the pressure regulating valve UA are driven. The brake fluid BF discharged from the fluid pump QA is throttled by the pressure regulating valve UA, thereby adjusting the servo fluid pressure Pa. The servo hydraulic pressure Pa is transmitted from the servo chamber Ru to the master chamber Rm via the master piston NM, and supplied as the supply hydraulic pressure Pm to the front wheel cylinder CWf. On the other hand, the servo hydraulic pressure Pa is directly supplied to the rear wheel cylinder CWr.

<First Processing Example of Pressure Regulation Control>
A first processing example of pressure regulation control in the fluid unit HU (in particular, the pressurizing unit KU) will be described with reference to the flowchart of FIG. "Pressure adjustment control" drives the electric motor MA to form a return KN of the brake fluid BF, and throttles the return KN with the pressure adjustment valve UA to control the servo hydraulic pressure Pa (finally, the brake fluid pressure Pw). Here, the fluid unit HU that adjusts the servo hydraulic pressure Pa using the return KN generated by the electric motor MA as a power source is called a "return type". In the pressure regulation control, the load state quantity Jm of the electric motor MA is considered to avoid stalling of the electric motor MA (that is, a phenomenon in which the electric motor stalls or stops due to an excessive load). Contains specific controls. The pressure regulation control algorithm is programmed into the microprocessor MP in the brake controller ECU.

The description assumes the following: The vehicle JV is an electric vehicle, and includes a regenerative braking device KC capable of generating a regenerative braking force Fg on the front wheels WHf. Pressure regulation control includes regenerative cooperative control. The "regenerative cooperative control" is braking control for decelerating the vehicle JV by linking the frictional braking force Fm by the fluid unit HU of the braking control device SC and the regenerative braking force Fg by the regenerative braking device KC.

In step S110, deceleration request value Bs, supply hydraulic pressure Pm, servo hydraulic pressure Pa, motor temperature Tm, circuit temperature Td (for example, element temperature), motor current value Im, pressure regulating valve current value Ia, motor rotation speed Ns, Various signals including the power supply voltage Vm and the like are read. Here, the deceleration request value Bs is a request value for decelerating the vehicle JV, and is a general term for the braking operation amount Ba and the target deceleration Gd. The supply hydraulic pressure Pm and the servo hydraulic pressure Pa are detected by a supply hydraulic pressure sensor PM and a servo hydraulic pressure sensor PA. The motor temperature Tm and circuit temperature Td are detected by a motor temperature sensor TM and circuit temperature sensor TD. The motor current value Im and the regulator valve current value Ia are detected by a current sensor ID (generic name). The motor rotation speed Ns is detected by a motor rotation speed sensor NS. A power supply voltage Vm (actual voltage of the power supply BU) is detected by a power supply voltage sensor VM.

At step S120, the target vehicle system power Fv is calculated based on the deceleration request value Bs (braking operation amount Ba or target deceleration Gd). The "target vehicle system power Fv" is a target value corresponding to the braking force Fb acting on the vehicle body (that is, the braking force of the vehicle JV as a whole). The target vehicle system power Fv is calculated to be "0" when the deceleration request value Bs is less than the predetermined amount bo based on the deceleration request value Bs and the calculation map Zfv. When the deceleration request value Bs is equal to or greater than the predetermined amount bo, the target vehicle system power Fv is calculated to increase from "0" as the deceleration request value Bs increases. Here, the predetermined amount bo is a preset predetermined value (constant).

In step S130, limit regenerative braking force Fx is obtained. The “limit regenerative braking force Fx” is the maximum value (limit value) of the regenerative braking force Fg that can be generated by the regenerative braking device KC. In other words, the limit regenerative braking force Fx is a state quantity (variable) representing the limit of the regenerative braking force Fg. The limit regenerative braking force Fx is determined based on the operating state of the regenerative braking device KC. Specifically, the operating state of the regenerative braking device KC includes the rotation speed Ng of the generator GN (that is, the front wheel speed Vwf), the state (temperature, etc.) of the regenerative controller EG (particularly, power transistors such as IGBTs), and It corresponds to at least one of the states (charge acceptance amount, temperature, etc.) of the running storage battery BT. The limit regenerative braking force Fx is determined (calculated) by the regenerative controller EG and input to the braking controller ECU via the communication bus BS.

At step S140, a target regenerative braking force Fh and a target frictional braking force Fn are calculated based on the target vehicle system power Fv and the limit regenerative braking force Fx. The "target regenerative braking force Fh" is a target value corresponding to the actual regenerative braking force Fg generated by the regenerative braking device KC. The "target frictional braking force Fn" is a target value corresponding to the actual frictional braking force Fm generated by the braking control device SC.

At step S140, it is determined whether or not the target vehicle system power Fv is greater than the limit regenerative braking force Fx. When the target vehicle system power Fv is equal to or less than the limit regenerative braking force Fx (that is, when "Fv≦Fx"), the target regenerative braking force Fh is calculated as the target vehicle system power Fv, and the target friction braking force Fn is computed to '0' (ie, 'Fh=Fv, Fn=0'). On the other hand, when the target vehicle system power Fv is greater than the limit regenerative braking force Fx (that is, when "Fqf>Fxf"), the target regenerative braking force Fh is calculated as the limit regenerative braking force Fx, and the target The frictional braking force Fn is calculated by subtracting the limit regenerative braking force Fx from the target vehicle system power Fv (that is, "Fh=Fx, Fn=Fv-Fx").

The target regenerative braking force Fh calculated in step S140 is transmitted from the braking controller ECU to the regenerative controller EG. Then, the regenerative controller EG controls the generator GN so that the actual regenerative braking force Fg approaches and matches the target regenerative braking force Fh.

At step S150, the target hydraulic pressure Pt is calculated based on the target frictional braking force Fn. The "target hydraulic pressure Pt" is a target value corresponding to the servo hydraulic pressure Pa (result, the actual braking hydraulic pressure Pw). Specifically, the target friction The braking force Fn is converted into the target hydraulic pressure Pt.

At step S160, the load state quantity Jm is calculated. The load state quantity Jm is a state quantity (variable) that expresses the load state (degree of load) of the electric motor MA. For example, the load state quantity Jm is calculated (determined) by at least one of the methods listed below.
(1) The load state quantity Jm is calculated based on the temperature Tm of the electric motor MA. For example, the temperature Tm of the electric motor MA is determined as the load state quantity Jm (that is, "Jm=Tm"). Here, the motor temperature Tm is detected by a motor temperature sensor TM provided in the electric motor MA.
(2) The load state quantity Jm is calculated based on the temperature Td of the drive circuit DD (particularly the switching element) that drives the electric motor MA. For example, the temperature Td of the drive circuit DD is determined as the load state quantity Jm (that is, "Jm=Td"). Here, the circuit temperature Td is detected by a circuit temperature sensor TD provided in the drive circuit DD.
(3) The load state quantity Jm is calculated based on the ratio Hm of the output of the electric motor MA to the actual current value Im supplied to the electric motor MA (detected value of the motor current sensor IM). For example, the ratio Hm is determined as the load state quantity Jm (that is, "Jm=Hm"). Here, the rotation speed Ns of the electric motor MA (detection value of the rotation speed sensor NS) is employed as the output of the electric motor MA. Also, the braking hydraulic pressure Pw (that is, the servo hydraulic pressure Pa, the supply hydraulic pressure Pm) may be employed as the output of the electric motor MA.
That is, the load state quantity Jm (the magnitude of the load on the electric motor MA) is the motor temperature Tm, the drive circuit temperature Td, and the output (for example, the actual servo fluid It is determined based on at least one of the pressure Pa, the actual supply hydraulic pressure Pm, and the actual motor rotation speed Ns).

At step S170, "whether or not the load of the electric motor MA is excessive (referred to as 'overload determination')" is determined. The overload determination predicts the probability of stalling of the electric motor MA. Specifically, the overload determination is based on the load state quantity Jm and determines whether or not the load state quantity Jm is equal to or greater than a predetermined quantity jm. The predetermined amount jm is a determination threshold in overload determination, and is a preset predetermined value (constant). When "Jm<jm", the motor load is relatively small, and the probability of motor stall is low, the overload determination is denied, and the process proceeds to step S180. On the other hand, when "Jm≧jm", the motor load is large, and the probability of motor stall is high, the overload determination is affirmative, and the process proceeds to step S190.

In step S180, normal pressure regulation control (referred to as "regular control") is executed. In regular control, the electric motor MA is driven based on the target hydraulic pressure Pt. Specifically, a target rotation speed Nt (a target value corresponding to the actual motor rotation speed Ns) is calculated based on the target hydraulic pressure Pt, and the supply current Im to the electric motor MA is adjusted based on the target rotation speed Nt. be done. For example, in the drive control of the electric motor MA, calculation is performed so that the target rotational speed Nt increases as the amount of change dP of the target hydraulic pressure Pt over time (that is, the time differential value of the target hydraulic pressure Pt) increases. . Then, pulse width modulation control (so-called PWM control) is performed so that the actual motor rotation speed Ns approaches and matches the target rotation speed Nt. In other words, rotation speed feedback control is performed in the drive control of the electric motor MA.

In the rotation speed feedback control, the deviation hN is calculated based on the target rotation speed Nt and the actual rotation speed Ns (the detected value of the motor rotation speed sensor NS or the time differential value of the detection value of the rotation angle sensor). (ie, “hN=Nt−Ns”). Then, the current value Im (for example, the duty ratio in PWM control) to the electric motor MA is adjusted so that the rotational speed deviation hN approaches and coincides with "0". Specifically, when the rotation speed deviation hN is greater than the predetermined rotation speed hn, the current value Im of the electric motor MA is increased, and the speed of the electric motor MA is increased. On the other hand, when the rotation speed deviation hN is less than the predetermined rotation speed "-hn", the current value Im of the electric motor MA is decreased, and the electric motor MA is decelerated. Here, the predetermined number of revolutions hn is a dead band of control, and is a preset predetermined value (positive sign constant). Note that the target rotation speed Nt may be a predetermined value (constant) that is set in advance instead of being a function of the target hydraulic pressure Pt.

Furthermore, in the regular control of step S180, the pressure regulating valve UA is driven based on the target hydraulic pressure Pt. Specifically, the supply current Ia of the pressure regulating valve UA is adjusted so that the servo hydraulic pressure Pa approaches and coincides with the target hydraulic pressure Pt. For example, in the current control for driving the pressure regulating valve UA, the target current value It (actual (target value corresponding to current value Ia) is increased. Then, the actual current value Ia is controlled to approach and match the target current value It (so-called current feedback control).

Furthermore, in the drive control of the pressure regulating valve UA, the target current value It may be adjusted so that the servo hydraulic pressure Pa approaches and matches the target hydraulic pressure Pt. Specifically, the deviation hP is calculated based on the target hydraulic pressure Pt and the servo hydraulic pressure Pa (that is, "hP=Pt-Pa"). Then, the current value Ia to the pressure regulating valve UA (for example, the duty ratio in PWM control) is adjusted so that the hydraulic pressure deviation hP approaches and coincides with "0". Specifically, when the hydraulic pressure deviation hP is greater than the predetermined hydraulic pressure hp, the target current value It (resulting in the actual current value Ia) of the pressure regulating valve UA is increased, and the valve opening amount of the pressure regulating valve UA is decreased. be. On the other hand, when the hydraulic pressure deviation hP is less than the predetermined hydraulic pressure "-hp", the current values It and Ia of the pressure regulating valve UA are decreased and the valve opening amount of the pressure regulating valve UA is increased. Here, the predetermined hydraulic pressure hp is a control dead zone and is a preset predetermined value (positive constant).

In step S190, pressure regulation control (referred to as "first specific control" or simply "specific control") is executed when the load on electric motor MA is excessive. In the first specific control, energization of the pressure regulating valve UA is restricted so that the electric motor MA does not stall and stop. In step S190, electric motor MA is driven in a manner similar to step S180. On the other hand, the supply current Ia to the pressure regulating valve UA is limited by a method described later.

<Restriction of energization of pressure regulating valve UA>
The energization limitation of the pressure regulating valve UA in the first specific control of step S190 will be described with reference to the characteristic diagram of FIG. The "energization limit" reduces the load on the electric motor MA by limiting the current Ia supplied to the pressure regulating valve UA so as to avoid stalling of the electric motor MA when the overload determination is affirmative. be. The characteristic diagram is a calculation map that expresses the relationship between the current value supplied and the hydraulic pressure output from the pressure regulating valve UA, and is called "IP characteristic". In the calculation map (IP characteristic) Zip, the horizontal axis indicates the target current value It (result, current value Ia), and the vertical axis indicates the target hydraulic pressure Pt (result, actual servo hydraulic pressure Pa).

Since the pressure regulating valve UA is of the normally open type, as the supply current Ia increases, the amount of valve opening decreases and the servo hydraulic pressure Pa (resulting in the supply hydraulic pressure Pm and the braking hydraulic pressure Pw) increases. In the operation map Zip, the point X is the maximum operating point required of the braking control device SC. Therefore, the rated value ix of the supply current (referred to as "rated current") corresponds to the rated value px (referred to as "rated hydraulic pressure") of the servo hydraulic pressure Pa required for the braking control device SC. In the normal control of step S180, the current value Ia of the pressure regulating valve UA is adjusted in the range from "0" to the rated current ix, thereby increasing the servo hydraulic pressure Pa from "0" to the rated hydraulic pressure px. (the range indicated by the two-dot chain line in the figure). The "rated hydraulic pressure px" corresponds to the maximum value of the servo hydraulic pressure Pa (resulting in the braking hydraulic pressure Pw) that can be continuously generated by the braking control device SC.

When the load of the electric motor MA is excessive (that is, when the overload determination in step S170 is affirmative), specific control in step S190 is performed to control the pressure regulating valve UA as indicated by the operating point S. Limits are provided so that the supplied current values It (target value) and Ia (actual value) do not exceed the limit current value Iz. By limiting the current values It and Ia to the limit current value Iz, the outputs (hydraulic pressures) Pt and Pa from the pressure unit KU are limited to the limit hydraulic pressure Pz. Here, the control result of the target hydraulic pressure Pt (target value) is the servo hydraulic pressure Pa (actual value). In the first specific control, the operating point of the braking control device SC is limited to the range from the origin (0, 0) to the point S (Iz, Pz) in the calculation map Zip (the range indicated by the dashed line in the figure). ).

For example, the load state quantity Jm representing the degree of load (degree of overload) of the electric motor MA is determined (computed) based on the temperature Tm of the electric motor MA and/or the temperature Td of the drive circuit DD of the electric motor MA. ) is done. This is based on the fact that the higher the load, the higher the temperatures Tm (temperature of the body of the electric motor MA) and Td (temperature of the drive circuit DD). Further, the load state quantity Jm is calculated based on the relationship between the input (ie motor current value Im) and the output (ie servo hydraulic pressure Pa, supply hydraulic pressure Pm, motor rotation speed Ns) in the electric motor MA. may Specifically, the ratio Hm of the output to the input is calculated, and the load state quantity Jm is determined according to the ratio Hm. Note that "the electric motor MA is in an overloaded state (affirmative condition for overload determination)" is defined as "the load state quantity Jm (variable) is equal to or greater than a predetermined amount jm (constant) set in advance". determined based on

When the overload determination is affirmative, the first specific control limits the target current value It (result, the actual current value Ia) to be equal to or less than the limit current value Iz. Due to this limitation, a current larger than the limit current value Iz is not supplied to the pressure regulating valve UA, so that the servo hydraulic pressure Pa is limited to the limit hydraulic pressure Pz or less. The limit current value Iz (variable) is calculated based on the load state quantity Jm and the calculation map Zjm, as shown in block X190. Specifically, according to the calculation map Zjm, the limit current value Iz is determined to decrease as the load state quantity Jm increases. Therefore, the larger the load state quantity Jm, the lower the limit hydraulic pressure Pz is set. Also, the limited current value Iz (result, the limited hydraulic pressure Pz) may be set as a preset predetermined value (constant). Since the first specific control limits the load on the electric motor MA, stalling of the electric motor MA can be avoided. Then, pressure regulation of the braking fluid pressure Pw by the pressure regulation valve UA can be continued.

For example, pulse width modulation control (PWM control) is executed in drive control of the pressure regulating valve UA. In PWM control, the duty ratio Du of the pulse width (in a periodic pulse wave, the ratio of the on-state pulse width to the period) is determined based on the target current value It and a preset calculation map. . The final voltage supplied to the pressure regulating valve UA is determined by the input voltage (which is the power supply voltage and the voltage of the storage battery BU) and the duty ratio Dt of the pressure regulating valve UA, and as a result, the current value Ia of the pressure regulating valve UA is determined. Therefore, when PWM control is adopted for driving the pressure regulating valve UA, the duty ratio Du may be limited in the limitation based on the limit current value Iz. That is, by limiting the duty ratio Du, the current value Ia is substantially limited.

Furthermore, the current limitation based on the load state quantity Jm may be performed by limiting the target hydraulic pressure Pt. This is because the pressure regulating valve UA controls the actual current Ia based on the target current value It corresponding to the target hydraulic pressure Pt. That is, by limiting the target hydraulic pressure Pt based on the load state quantity Jm, the actual current value Ia can be limited.

<Second Processing Example of Pressure Regulation Control>
A second processing example of the pressure regulation control will be described with reference to the flowchart of FIG. In the first processing example, the current value Ia is limited based on the load state quantity Jm representing the overload state of the electric motor MA. Instead of this, in the second processing example, the current value Ia is limited based on the power supply voltage Vm of the electric motor MA (that is, the voltage of the storage battery BU). In the second processing example, the same calculation processing as in the first processing example is performed in the calculation steps denoted by the same symbols as in the first processing example (that is, steps S110 to S150 and step S180). Therefore, the description of the processing in these calculation steps is omitted. Differences from the first processing example will be described below.

In step S200, it is determined whether or not the voltage Vm of the storage battery BU (power source) for auxiliary equipment is decreasing (referred to as "voltage drop determination"). The power supply voltage Vm is a voltage input (supplied) from the storage battery BU to the drive circuit DD in order to drive the electric motor MA. For example, the power supply voltage Vm is detected by a power supply voltage sensor VM provided in the drive circuit DD. Specifically, the voltage drop determination is made based on "whether or not the power supply voltage Vm is less than the predetermined voltage vm". Here, the predetermined voltage vm is a preset predetermined value (constant). If "Vm≧vm", the voltage drop determination in step S200 is negative, the process proceeds to step S180, and normal control is executed. On the other hand, if "Vm<vm", the power supply voltage Vm has dropped, so the voltage drop determination in step S200 is affirmative, and the process proceeds to step S210.

In step S210, voltage regulation control (referred to as "second specific control" or simply "specific control") is executed when power supply voltage Vm of electric motor MA is low. In the second specific control, similarly to the first specific control, the energization of the pressure regulating valve UA is restricted so that the electric motor MA does not stall and stop. Also in step S210, the electric motor MA is driven in the same manner as in step S180. On the other hand, the supply current Ia to the pressure regulating valve UA is limited by the same method as in step S190.

With reference again to the characteristic diagram of FIG. 4, the energization limitation of the pressure regulating valve UA in the specific control of step S210 will be described. The energization restriction by the second specific control restricts the current Ia supplied to the pressure regulating valve UA so as to avoid stalling of the electric motor MA when the determination of the decrease in the power supply voltage Vm is affirmative. It is intended to reduce the load on When the power supply voltage Vm of the electric motor MA is lowered (that is, when the determination in step S200 is affirmative), the current It (target value), Ia (actual value) is limited by the limiting current value Iz. As a result, the hydraulic pressures Pt (target value) and Pa (actual value) from the pressurizing unit KU are limited to the limit hydraulic pressure Pz or less (see operating point S). That is, in the second specific control, as in the first specific control, the operating point of the braking control device SC is set in the range from the origin (0, 0) to the point S (Iz, Pz) in the calculation map Zip. Limited (range indicated by dashed lines in the figure). The power supply voltage Vm is detected by a power supply voltage sensor VM provided in the drive circuit DD.

When the voltage drop determination is affirmative, the second specific control limits the target current value It (result, current value Ia) so as not to exceed the limit current value Iz. Due to this restriction, a current greater than the limit current value Iz is not supplied to the pressure regulating valve UA, so the servo hydraulic pressure Pa (resulting in the supply hydraulic pressure Pm and the braking hydraulic pressure Pw) is limited to the range up to the limit hydraulic pressure Pz. be done. Limiting current value Iz (variable) is calculated based on power supply voltage Vm and calculation map Zvm, as shown in block X190. Specifically, according to the calculation map Zvm, the smaller the power supply voltage Vm, the smaller the limit current value Iz. Therefore, the limit hydraulic pressure Pz is set lower as the degree of decrease in the power supply voltage Vm increases. Also, the limited current value Iz (result, the limited hydraulic pressure Pz) may be set as a preset predetermined value (constant). Since the load on the electric motor MA is limited by the second specific control, stalling of the electric motor MA can be avoided, and pressure regulation control of the braking fluid pressure Pw by the pressure regulation valve UA can be continued. Note that, as described above, when the pressure regulating valve UA is driven by PWM control, the duty ratio Du may be limited in the current limitation. This is based on the fact that the current value Ia is substantially limited by limiting the duty ratio Du.

Similarly to the above, the current limit may be performed by limiting the target hydraulic pressure Pt. Current control of the pressure regulating valve UA is performed according to a target current value It calculated based on the target hydraulic pressure Pt. Therefore, by limiting the target hydraulic pressure Pt based on the power supply voltage Vm, the actual current value Ia can be limited.

<Second Configuration Example of Fluid Unit HU>
A second configuration example of the fluid unit HU will be described with reference to the schematic diagram of FIG. The fluid unit HU according to the second configuration example is also applied to the vehicle JV having the regenerative braking device KC for the front wheels WHf. In the second configuration example, members (such as MA) denoted by the same symbols as in the first configuration example have the same functions as in the first configuration example. Therefore, differences from the first configuration example will be described. In the example, the fluid unit HU is configured such that the pressure receiving areas ru and rm are the same.

In the second configuration example, a second pressure regulating valve UB is provided between the fluid pump QA and the pressure regulating valve UA (also referred to as "first pressure regulating valve") in the return path HK. The second pressure regulating valve UB is a normally open linear solenoid valve similar to the first pressure regulating valve UA. In the second configuration example, the damping fluid BF discharged by the fluid pump QA is adjusted by being throttled in two stages. Here, the hydraulic pressure Pa between the first pressure regulating valve UA and the second pressure regulating valve UB is referred to as "first servo hydraulic pressure". Further, the hydraulic pressure Pb between the second pressure regulating valve UB and the fluid pump QA is referred to as "second servo hydraulic pressure". The second servo hydraulic pressure Pb is adjusted to increase from the first servo hydraulic pressure Pa by the second pressure regulating valve UB. Therefore, regarding the magnitude relationship between the first servo hydraulic pressure Pa and the second servo hydraulic pressure Pb, the second servo hydraulic pressure Pb is always greater than or equal to the first servo hydraulic pressure Pa (that is, "Pb≧Pa"). The second pressure regulating valve UB is controlled by a drive signal Ub. Further, the fluid unit HU is provided with first and second servo hydraulic pressure sensors PA, PB to detect the first and second servo hydraulic pressures Pa, Pb.

The return path HK is connected to the servo chamber Ru via a servo path HV at a portion Xa between the first pressure regulating valve UA and the second pressure regulating valve UB. Therefore, the first servo hydraulic pressure Pa is supplied to the servo chamber Ru and output from the master chamber Rm as the supplied hydraulic pressure Pm (that is, "ru=rm", so "Pm=Pa=Pwf"). . Further, the return passage HK is connected to the rear wheel cylinder CWr via the rear wheel communication passage HSr at the portion Xb between the fluid pump QA and the second pressure regulating valve UB. Therefore, the second servo hydraulic pressure Pb is supplied to the rear wheel cylinder CWr (that is, "Pb=Pwr"). In the second configuration example, the front wheel braking hydraulic pressure Pwf and the rear wheel braking hydraulic pressure Pwr are individually adjusted within the range of "Pwf≦Pwr". , while the ratio between the front wheel braking force Fxf and the rear wheel braking force Fxr (so-called front/rear braking force distribution) is kept constant, the cooperative regenerative control can be executed.

Also in the second configuration example, similarly to the first configuration example, when at least one of the overload determination (see step S170) and the voltage drop determination (see step S200) is affirmative, The energization of the first and second pressure regulating valves UA and UB is restricted as described with reference to FIGS. As a result, the motor stall is avoided, and the pressure regulation control by the first and second pressure regulation valves UA, UB can be continued without being interrupted by the motor stall.

When the fluid unit HU according to the second configuration example is applied to the vehicle JV having the regenerative braking device KC for the rear wheel WHr, the first servo hydraulic pressure Pa is supplied to the rear wheel cylinder CWr, A second servo hydraulic pressure Pb is supplied to the servo chamber Ru. Even in this configuration, the same effect as described above can be obtained by performing the energization limitation described above.

<Another Configuration Example of Fluid Unit HU>
As the fluid unit HU of the braking control device SC according to the present invention, there is an example of a configuration including a single master cylinder CM and CN (see FIG. 2), and an example of configuration including a pressure unit KU capable of adjusting pressure in two stages (see FIG. 6). ) was explained. Instead of these, in the braking control device SC according to the present invention, as the fluid unit HU, a configuration including a tandem-type master cylinder CM (see, for example, Japanese Unexamined Patent Application Publication No. 2020-032833), a wheel cylinder CW and a pressure unit KU. may be connected via an electromagnetic valve (for example, see JP-A-2021-014157). In any case, in the fluid unit HU included in the braking control device SC according to the present invention, the brake fluid BF discharged by the fluid pump QA driven by the electric motor MA is adjusted by the pressure regulating valve (UA etc.).

Furthermore, the above configuration example is a brake-by-wire type that generates the operating force Fp of the braking operation member BP in the stroke simulator SS, and the service brake ("regular brake" (also called). Alternatively, the pressurizing unit KU may be operated only to execute vehicle stability control or regenerative cooperative control (particularly, switching operation immediately before the vehicle stops) without being used for service braking. Good (see, for example, JP-A-2014-213854 and JP-A-2015-095966).

It is more effective to apply the energization limitation by the first and second specific controls to the braking control device SC that implements the service brake. For example, when the electric motor MA stops while the service brake is operating, the adjustment of the brake fluid pressure Pw is changed from that by the pressurizing unit KU to pressurization by manual braking (braking only by the driver's muscle strength). I have to switch to. However, although the braking control device SC limits the rated hydraulic pressure px that can be generated by the pressurizing unit KU, the electric motor MA continues to be driven, so the pressure regulation control by the pressurizing unit KU can be continued. In other words, when an overload condition or the like occurs in the electric motor MA, it is not possible to immediately switch to manual braking. Therefore, when the braking control device SC malfunctions, sudden deterioration in performance does not occur, and the continuity of the pressure regulation control is ensured, so that the sense of discomfort felt by the driver can be reduced.

<Summary of Embodiment of Braking Control Device SC>
Embodiments of the braking control device SC according to the present invention are summarized below. The braking control device SC includes a "pressurizing unit KU for adjusting the pressure Pa (servo fluid pressure) of the braking fluid BF discharged by the fluid pump QA driven by the electric motor MA by means of the pressure regulating valve UA", and a "pressurizing unit A controller ECU that adjusts the brake hydraulic pressure Pw of the wheel cylinder CW by controlling KU.

In the braking control device SC, the controller ECU determines the current value (Ia, etc.) supplied to the pressure regulating valve (UA, etc.) based on the load state quantity Jm representing the degree (magnitude) of the load on the electric motor MA. restrictions are made. This current limitation is not executed when the load state quantity Jm is less than the predetermined quantity jm, but is executed when the load state quantity Jm is equal to or greater than the predetermined quantity jm. Specifically, the load state quantity Jm is calculated based on the temperature Tm of the electric motor MA. Also, the load state quantity Jm can be calculated based on the temperature Td of the circuit DD that drives the electric motor MA (in particular, the driving element of the electric motor MA). Furthermore, the load state quantity Jm may be calculated based on the ratio Hm of the motor output to the supply current value Im in the electric motor MA. Here, at least one of the servo hydraulic pressures Pa and Pb, the supply hydraulic pressure Pm, and the motor rotation speed Ns is adopted as the state quantity related to the output of the electric motor MA.

In the reflux type pressurizing unit KU, the servo hydraulic pressure Pa and the like are adjusted by the orifice effect when the brake fluid BF discharged from the fluid pump QA is throttled by the pressure regulating valve UA and the like. Specifically, the (first) pressure regulating valve UA (hereinafter, the same applies to the second pressure regulating valve UB) is a normally open linear electromagnetic valve, and is controlled by the braking controller ECU. The pressure regulating valve UA includes a valve element driven by a solenoid, and when the solenoid is energized, the solenoid generates a thrust force (referred to as "attractive force") that pulls the plunger into the fixed coil. This suction force acts on the valve element fixed to the solenoid to prevent the braking fluid BF from the fluid pump QA from flowing into the pressure regulating valve UA. Here, the force acting on the valve element by the damping fluid BF is referred to as "fluid force". The suction force of the valve element of the pressure regulating valve UA and the fluid force due to the flow of the braking fluid BF (that is, the return KN) oppose each other. When the suction force and the fluid force are in balance, the opening amount of the pressure regulating valve UA (that is, the gap between the valve element and the valve seat) is determined, and the servo hydraulic pressure Pa is determined.

The electric motor MA is designed in such a way that it can generate a rated hydraulic pressure px (maximum hydraulic pressure that can be achieved continuously). That is, the electric motor MA has sufficient power to generate the rated hydraulic pressure px. However, if the load state quantity Jm of the electric motor MA becomes excessive, a situation may arise in which the output of the electric motor MA is relatively reduced. For example, the following situations are assumed.
- Increased torque losses due to increased friction in the bearings (eg bearings) of the electric motor MA and/or the fluid pump QA.
- Increased torque losses due to increased friction at the joints between the electric motor MA and the fluid pump QA.
- Increased torque loss due to contamination of fluid pump QA.
- Power loss due to overheating of the electric motor MA.

As described above, the fluid force of the brake fluid BF is generated using the electric motor MA as the power source. Affected by an increase in torque loss, the output of the electric motor MA relatively decreases, and when the fluid force corresponding to the suction force of the pressure regulating valve UA cannot be generated, the servo hydraulic pressure Pa (resulting in the braking hydraulic pressure Pw) Adjustment becomes difficult. Moreover, if the torque loss further increases, the probability of occurrence of motor stall (a phenomenon in which the electric motor MA stalls and stops) increases. If the motor stalls, the power to generate the circulating flow KN is lost, so the servo hydraulic pressure Pa (resultingly, the braking hydraulic pressure Pw) cannot be generated. Under this circumstance, the braking by the braking control device SC is switched to manual braking (braking by the driver's muscle strength only).

In the braking control device SC according to the present invention, when the load state quantity Jm becomes excessive (that is, when "Jm≧jm"), the current value It (target value), Ia (actual value ) is limited to the limit current value Iz. As a result, the suction force in the pressure regulating valve UA (that is, the force acting as resistance to the fluid force of the return KN) is limited. Therefore, occurrence of stall in the electric motor MA can be avoided. As a result, the adjustment control of the braking fluid pressure Pw by the braking control device SC (in particular, the pressurizing unit KU) can be maintained without being interrupted. That is, even when the load on the electric motor MA becomes excessive, the pressure regulation control with the limited rated hydraulic pressure is continued. Therefore, even if the electric motor MA is overloaded, the manual braking cannot be switched immediately, so that the driver's sense of discomfort is suppressed.

The degree of relative output reduction of the electric motor MA due to the increase in load depends on the load state quantity Jm. Therefore, it is desirable that the larger the load state quantity Jm, the smaller the limiting current Iz (see the calculation map Zjm of block X190). However, even if the limit current Iz is preset as a predetermined value (constant), the motor stall can be prevented.

In the braking control device SC, the controller ECU limits the current value (such as Ia) supplied to the pressure regulating valve (such as UA) based on the power supply voltage Vm of the electric motor MA. Here, the power supply voltage Vm is the output voltage of the storage battery BU and the input voltage to the drive circuit DD. Current limitation is not performed when the power supply voltage Vm is equal to or higher than the predetermined voltage vm, but is performed when the power supply voltage Vm is less than the predetermined voltage vm.

When the power supply voltage Vm drops, a phenomenon similar to the above-described situation where the load state quantity Jm becomes excessive (that is, the output of the electric motor MA relatively drops and the probability of motor stalling increases) occurs. can. In the braking control device SC, when the power supply voltage Vm drops (that is, when "Vm<vm"), the current values It (target value) and Ia (actual value) to the pressure regulating valve UA are limited. Furthermore, the limiting current Iz may be set in advance as a predetermined value (constant), but is preferably set so that the lower the power supply voltage Vm, the smaller the limiting current Iz (using the calculation map Zvm of block X190 as reference). By limiting the current of the pressure regulating valve, the same effect as described above (that is, prevention of motor stall) can be achieved.

SC: braking control device, BP: braking operation member, CM: master cylinder, CW: wheel cylinder, HU: fluid unit, KU: pressure unit, QA: fluid pump, MA: electric motor (for driving fluid pump QA) , UA...pressure regulating valve (first pressure regulating valve), UB...second pressure regulating valve, ECU...controller (for braking), BA...braking operation amount sensor, Ba...braking operation amount, Pt...target fluid pressure, It...target current Value, Ia...actual current value, ID...current sensor (generic name), IA...regulator valve current sensor, IM...motor current sensor, Pa...servo hydraulic pressure (first servo hydraulic pressure), Pb...second servo hydraulic pressure , Pm...supply hydraulic pressure, PA...servo hydraulic pressure sensor (first servo hydraulic pressure sensor), PB...second servo hydraulic pressure sensor, PM...supply hydraulic pressure sensor, Jm...load state quantity, Vm...power supply voltage, VM Power supply voltage sensor BU Storage battery for auxiliary equipment (power supply) DD Drive circuit Pw Brake fluid pressure Tm Motor temperature TM Temperature sensor Td Drive circuit temperature (e.g. element temperature) TD temperature sensor, Ns...motor speed, NS...motor speed sensor.

Claims (4)

A vehicle comprising: a pressurization unit that adjusts the pressure of brake fluid discharged by a fluid pump driven by an electric motor with a pressure regulating valve; and a controller that adjusts the brake fluid pressure of the wheel cylinder by controlling the pressurization unit. In the braking control device of
The controller is
A braking control device for a vehicle, wherein a current value to the pressure regulating valve is limited based on a load state quantity representing the degree of load on the electric motor. In the vehicle braking control device according to claim 1,
The controller is
A braking control device for a vehicle, wherein the restriction is not executed when the load state quantity is less than a predetermined amount, and the restriction is executed when the load state quantity is equal to or greater than the predetermined amount. A vehicle comprising: a pressurization unit that adjusts the pressure of brake fluid discharged by a fluid pump driven by an electric motor with a pressure regulating valve; and a controller that adjusts the brake fluid pressure of the wheel cylinder by controlling the pressurization unit. In the braking control device of
The controller is
A braking control device for a vehicle, which limits a current value to the pressure regulator valve based on the power supply voltage of the electric motor. In the vehicle braking control device according to claim 3,
The controller is
A braking control device for a vehicle, wherein the restriction is not performed when the power supply voltage is equal to or higher than a predetermined voltage, and the restriction is performed when the power supply voltage is less than the predetermined voltage.

Images