JP5293862B2 - Brake control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brake control device that sufficiently ensures a braking force on the occurrence of abnormal conditions. <P>SOLUTION: The brake control device generates the braking force in conjunction with a hydraulic brake force and a regenerative braking force. The brake control device includes: a control unit which calculates a required value of the regenerative braking force generated subsidiarily on the occurrence of abnormal conditions; and a plurality of sensors each of which outputs, to the control unit, a detected value fluctuating synchronously with a braking operation by a driver. The control unit selects any one of the plurality of sensors and calculates the required value based on the detected value by the selected sensor. <P>COPYRIGHT: (C)2013,JPO&amp;INPIT

Description

  The present invention relates to a brake control device that controls braking force applied to wheels provided in a vehicle.

  For example, Patent Document 1 describes a brake control device using a so-called brake-by-wire. The brake-by-wire detects a driver's brake operation and generates a driver's required braking force by electronic control. In this brake control device, each wheel cylinder pressure can be controlled in common by a pair of linear control valves, which is preferable from the viewpoint of cost reduction as compared with the case where a linear control valve is provided for each wheel cylinder. When the system is normal, the wheel cylinder pressure is controlled in common, and when an abnormality is detected, the separation valve is closed and the brake system is separated into two systems. Further, when the system is normal, the requested braking torque requested by the driver is the total braking torque that is the sum of the regenerative braking torque applied to the driving wheel and the friction braking torque applied to both the driving wheel and the driven wheel. Regenerative cooperative control is performed.

JP 2006-123889 A

  By the way, it is important from the viewpoint of fail-safe to ensure a sufficient braking force even when an abnormality is detected. Further, in order to effectively secure the braking force when an abnormality is detected, it is preferable to specify the location where the abnormality has occurred and the content of the abnormality.

  Accordingly, an object of the present invention is to provide a brake control device that can sufficiently secure a braking force when an abnormality occurs.

  A brake control device according to an aspect of the present invention is a brake control device that generates a braking force by using both a hydraulic braking force and a regenerative braking force, and pressurizes hydraulic fluid in response to a driver's brake operation input. A manual that includes one hydraulic fluid chamber and a second hydraulic fluid chamber that is connected to transmit the hydraulic fluid pressure of the first hydraulic fluid chamber and pressurizes the hydraulic fluid according to the hydraulic pressure of the first hydraulic fluid chamber. A braking force is applied to a hydraulic pressure source, a first wheel cylinder that applies a braking force to the first wheel according to the hydraulic pressure, and a second wheel that is different from the first wheel according to the hydraulic pressure. A second hydraulic cylinder, a first hydraulic fluid supply path that connects the first hydraulic fluid chamber and the first wheel cylinder, a second hydraulic fluid supply path that connects the second hydraulic fluid chamber and the second wheel cylinder, The first and second wheel are provided in parallel with the first and second hydraulic fluid supply paths. A wheel cylinder pressure control system for controlling the cylinders to a common hydraulic pressure, a common hydraulic pressure control mode for controlling the first and second wheel cylinders to a common hydraulic pressure by the wheel cylinder pressure control system, and first and second Select one of a plurality of brake modes including: individual hydraulic pressure modes for supplying hydraulic pressure in the hydraulic fluid chamber to the first and second wheel cylinders using the first and second hydraulic fluid supply paths, respectively. In the common hydraulic pressure control mode, the operating hydraulic pressure is controlled to supplement the regenerative braking force and generate the required braking force. In the individual hydraulic pressure mode, the regenerative braking force is supplemented to the hydraulic braking force. A control unit that calculates a required value of the regenerative braking force to be added to the motor, a stroke sensor that measures a stroke of a brake pedal that receives a brake operation input and outputs the stroke to the control unit, and a first hydraulic fluid supply A first hydraulic pressure sensor that is disposed in the path and measures the common hydraulic pressure in the common hydraulic pressure control mode and measures the hydraulic pressure in the first hydraulic fluid supply path in the individual hydraulic pressure mode and outputs the measured hydraulic pressure to the control unit; In the common hydraulic pressure control mode, the hydraulic pressure in the second hydraulic fluid chamber is measured, and in the individual hydraulic pressure mode, the hydraulic pressure in the second hydraulic fluid supply path is measured and controlled. A second hydraulic pressure sensor that outputs to the unit. The control unit switches the brake mode to the individual hydraulic pressure mode when an abnormality is detected in the common hydraulic pressure control mode, and the stroke sensor, the first hydraulic pressure sensor, and the second hydraulic pressure sensor are switched in the individual hydraulic pressure mode. One of them is selected, and a required value of the regenerative braking force to be supplementarily added is calculated based on the measured value of the selected sensor.

  According to this aspect, when the device is normal, for example, the common hydraulic pressure mode is selected, and at this time, the brake control device makes a request using the hydraulic braking force complementarily while preferentially using the regenerative braking force. Generate braking force. By using the regenerative braking force preferentially, the fuel efficiency of the vehicle can be improved. On the other hand, when an abnormality is detected, the individual hydraulic pressure mode is selected so that the hydraulic fluid is individually supplied for each hydraulic fluid supply system. Thereby, the brake control excellent in fail-safe property is realized. Furthermore, since the regenerative braking force is supplementarily added at this time, a sufficient braking force can be ensured. The required value of the regenerative braking force to be supplementarily added is calculated based on the measurement result of any one of the plurality of sensors. Therefore, it is possible to effectively assist the hydraulic braking force with the regenerative braking force and to obtain sufficient braking force and controllability even in an abnormal state by appropriately selecting the sensor that is the basis of the calculation. Become.

  The control unit may specify the occurrence location of the abnormality based on the measurement values of the stroke sensor, the first hydraulic pressure sensor, and the second hydraulic pressure sensor.

  By determining by combining the measurement values of a plurality of sensors, it is possible to specify the location where the abnormality has occurred in more detail. In particular, it is possible to specify whether an abnormality has occurred in a specific sensor itself.

  The control unit may select a sensor determined to have the highest reliability based on the specified abnormality occurrence location and calculate the required value.

  By selecting a sensor that is determined to have high reliability, it is possible to calculate an appropriate regenerative braking force request value according to the situation, and good braking performance can be obtained.

  The control unit may select one of the stroke sensor, the first hydraulic pressure sensor, and the second hydraulic pressure sensor so that the required value is maximized.

  By selecting the sensor that is the basis for calculating the regenerative braking force request value so that the required value is large, it is possible to generate a sufficiently large auxiliary regenerative braking force without judging the sensor reliability. Become.

  The control unit identifies which of the first and second hydraulic fluid supply paths is abnormal, and generates a regenerative braking force on the wheel to which the hydraulic braking force is to be applied through the path where the abnormality is occurring. May be.

  In this way, a corresponding regenerative braking force can be supplementarily or alternatively applied to a wheel in which an abnormality occurs and a decrease or disappearance of the hydraulic braking force is expected. Therefore, the influence on the vehicle deceleration and braking force distribution that may be caused by the abnormality is reduced, and the safety can be further improved.

  When the control for repeatedly increasing or decreasing the wheel cylinder pressure is performed on at least one wheel in order to suppress the lock of the wheel, the control unit applies regenerative braking force to the wheel on which the control is not performed. You may continue.

  If it does in this way, provision of regenerative braking power will be continued about a wheel in which so-called ABS control is not performed, for example, and it contributes to securing of braking power. In this case, the application of the regenerative braking force may be stopped for the wheels on which the ABS control is being executed.

  When the control for repeatedly increasing / decreasing the wheel cylinder pressure in order to suppress the lock of the wheel is performed on the second wheel in the individual hydraulic pressure mode, the measurement value of the second hydraulic pressure sensor is fluctuated. You may use the measured value of a 2nd hydraulic pressure sensor for calculation of a required value, after performing a filter process so that it may be relieved.

  In this way, when calculating the required value of the regenerative braking force, the influence of fluctuations in the wheel cylinder pressure for suppressing wheel lock on the measured value of the second hydraulic pressure sensor is alleviated. Therefore, the required value of the regenerative braking force can be further stabilized.

  The control unit increases the measured value of the second hydraulic pressure sensor when the control to repeatedly increase or decrease the wheel cylinder pressure to suppress the lock of the wheel is performed on the second wheel in the individual hydraulic pressure mode. When the measured value decreases compared to the case, the fluctuation of the required value may be suppressed.

  If it does in this way, the fluctuation | variation of the regenerative braking force required value when it will reduce among the increase / decrease in the wheel cylinder pressure for suppressing the lock | rock of a wheel will be suppressed. For this reason, since it is possible to suppress a sudden decrease in the regenerative braking force request value that is directly synchronized with the increase or decrease in the wheel cylinder pressure, it contributes to securing the braking force.

  Another aspect of the present invention is also a brake control device. This device is a brake control device that generates a braking force by using a combination of a hydraulic braking force and a regenerative braking force, a control unit that calculates a required value of the regenerative braking force that is auxiliary generated in the event of an abnormality, A plurality of sensors, each of which outputs a detection value that fluctuates in conjunction with a person's brake operation to the control unit. The control unit selects any one of the plurality of sensors and uses the detection value of the selected sensor as a basis for calculating the required value.

  Yet another embodiment of the present invention is also a brake control device. This device is a brake control device that generates a braking force by using both a hydraulic braking force and a regenerative braking force, and uses the regenerative braking force preferentially and complementarily using the hydraulic braking force to obtain the required braking force. The braking force is controlled by selecting one of a plurality of control modes including a regeneration priority mode to be generated and a regeneration assisting mode in which the regeneration braking force is added to the hydraulic braking force corresponding to the driver's braking operation. A control unit is provided. The control unit switches the control mode to the regeneration assist mode when an abnormality is detected in the regeneration priority mode.

  According to the present invention, it is possible to ensure a sufficient braking force when an abnormality occurs.

1 is a schematic configuration diagram illustrating a vehicle to which a brake control device according to an embodiment of the present invention is applied. It is a systematic diagram showing a hydraulic brake unit concerning this embodiment. It is a flowchart for demonstrating the regeneration assistance control which concerns on this embodiment. It is a graph for demonstrating an example of the abnormal location specific process which concerns on this embodiment. It is a graph for demonstrating an example of the abnormal location specific process which concerns on this embodiment. It is a flowchart for demonstrating an example of the abnormal location specific process which concerns on this embodiment. It is a graph for demonstrating an example of the abnormal location specific process which concerns on this embodiment.

  In the brake control device according to the present embodiment, in order to improve the fuel efficiency of the vehicle, the braking force due to regeneration of the motor (referred to as “regenerative braking force” in this specification as appropriate) and the friction braking force due to hydraulic pressure (in this specification) A required braking force is generated by executing a brake regeneration cooperative control using a combination of “hydraulic braking force” as appropriate. The regenerative braking force is a braking force applied to the wheel by operating an electric motor for driving the wheel as a generator that receives the rotational torque of the traveling wheel. The kinetic energy of the vehicle is converted into electric energy, and the electric energy is accumulated in the storage battery from the electric motor through a power conversion device including an inverter and the like. The accumulated electric energy is used for driving the wheels and the like, and contributes to improving the fuel consumption of the vehicle. On the other hand, the hydraulic braking force is a braking force applied to the wheel by pressing the friction member against the rotating member that rotates together with the wheel by supplying hydraulic fluid from the hydraulic pressure source. In order to further improve the fuel consumption, it is preferable to preferentially use the regenerative braking force, and to supplementarily generate the amount that is insufficient for the required braking force by the regenerative braking force by the hydraulic braking force.

  FIG. 1 is a schematic configuration diagram illustrating a vehicle to which a brake control device according to an embodiment of the present invention is applied. A vehicle 1 shown in the figure is configured as a so-called hybrid vehicle, and includes an engine 2, a three-shaft power split mechanism 3 connected to a crankshaft that is an output shaft of the engine 2, and a power split mechanism 3. A motor generator 4 capable of generating electricity, an electric motor 6 connected to the power split mechanism 3 via a transmission 5, and an electronic control unit for hybrid (hereinafter referred to as “hybrid ECU”) that controls the entire drive system of the vehicle 1. The electronic control unit is all referred to as “ECU”). A right front wheel 9FR and a left front wheel 9FL, which are drive wheels of the vehicle 1, are connected to the transmission 5 via a drive shaft 8.

  The engine 2 is an internal combustion engine that is operated using a hydrocarbon-based fuel such as gasoline or light oil, and is controlled by the engine ECU 13. The engine ECU 13 can communicate with the hybrid ECU 7, and performs fuel injection control, ignition control, intake control, etc. of the engine 2 based on control signals from the hybrid ECU 7 and signals from various sensors that detect the operating state of the engine 2. Run. Further, the engine ECU 13 gives information regarding the operating state of the engine 2 to the hybrid ECU 7 as necessary.

  The power split mechanism 3 transmits the output of the electric motor 6 to the left and right front wheels 9FR, 9FL via the transmission 5, distributes the output of the engine 2 to the motor generator 4 and the transmission 5, and the electric motor. 6 and the speed of the engine 2 is reduced or increased. The motor generator 4 and the electric motor 6 are each connected to a battery 12 via a power converter 11 including an inverter, and a motor ECU 14 is connected to the power converter 11. As the battery 12, for example, a storage battery such as a nickel hydride storage battery can be used. The motor ECU 14 can also communicate with the hybrid ECU 7 and controls the motor generator 4 and the electric motor 6 via the power converter 11 based on a control signal from the hybrid ECU 7 or the like. The hybrid ECU 7, engine ECU 13, and motor ECU 14 described above are all configured as a microprocessor including a CPU. In addition to the CPU, a ROM that stores various programs, a RAM that temporarily stores data, and an input / output port And a communication port.

  The left and right front wheels 9FR and 9FL can be driven by the output of the electric motor 6 by supplying electric power from the battery 12 to the electric motor 6 via the power converter 11 under the control of the hybrid ECU 7 and the motor ECU 14. . Further, the vehicle 1 is driven by the engine 2 in a driving region where the engine efficiency is good. At this time, by transmitting a part of the output of the engine 2 to the motor generator 4 via the power split mechanism 3, the electric motor 6 is driven using the electric power generated by the motor generator 4 or the power conversion device 11 is operated. It is possible to charge the battery 12.

  When the vehicle 1 is braked, the electric motor 6 is rotated by the power transmitted from the front wheels 9FR and 9FL under the control of the hybrid ECU 7 and the motor ECU 14, and the electric motor 6 is operated as a generator. That is, the electric motor 6, the power converter 11, the hybrid ECU 7, the motor ECU 14, and the like function as a regenerative brake unit 10 that applies braking force to the left and right front wheels 9FR, 9FL by regenerating the kinetic energy of the vehicle 1 into electric energy. To do.

  In addition to the regenerative brake unit 10, the vehicle 1 includes a hydraulic brake unit 20 that generates a braking force by supplying hydraulic fluid from a power hydraulic pressure source 30 or the like, as shown in FIG. 2. The vehicle braking device of the present embodiment is capable of braking the vehicle 1 by executing brake regeneration cooperative control in which the regenerative brake unit 10 and the hydraulic brake unit 20 are coordinated. The vehicle 1 in the present embodiment can generate a desired braking force by using the regenerative braking force and the hydraulic braking force together by executing the brake regeneration cooperative control.

  FIG. 2 is a system diagram showing the hydraulic brake unit 20 according to the present embodiment. As shown in FIG. 2, the hydraulic brake unit 20 includes disc brake units 21FR, 21FL, 21RR and 21RL provided for each wheel, a master cylinder unit 27, a power hydraulic pressure source 30, a hydraulic brake unit 20 Pressure actuator 40.

  Disc brake units 21FR, 21FL, 21RR, and 21RL apply braking force to the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel of the vehicle, respectively. The master cylinder unit 27 as the manual hydraulic pressure source in the present embodiment sends the brake fluid pressurized according to the operation amount by the driver of the brake pedal 24 as the brake operation member to the disc brake units 21FR to 21RL. To do. The power hydraulic pressure source 30 can send the brake fluid as the working fluid pressurized by the power supply to the disc brake units 21FR to 21RL independently from the operation of the brake pedal 24 by the driver. is there. The hydraulic actuator 40 appropriately adjusts the hydraulic pressure of the brake fluid supplied from the power hydraulic pressure source 30 or the master cylinder unit 27 and sends it to the disc brake units 21FR to 21RL. Thereby, the braking force with respect to each wheel by hydraulic braking is adjusted.

  Each of the disc brake units 21FR to 21RL, the master cylinder unit 27, the power hydraulic pressure source 30, and the hydraulic actuator 40 will be described in more detail below. Each of the disc brake units 21FR to 21RL includes a brake disc 22 and wheel cylinders 23FR to 23RL incorporated in the brake caliper, respectively. The wheel cylinders 23FR to 23RL are connected to the hydraulic actuator 40 via different fluid passages. Hereinafter, the wheel cylinders 23FR to 23RL are collectively referred to as “wheel cylinders 23” as appropriate.

  In the disc brake units 21FR to 21RL, when brake fluid is supplied to the wheel cylinder 23 from the hydraulic actuator 40, a brake pad as a friction member is pressed against the brake disc 22 that rotates together with the wheel. Thereby, a braking force is applied to each wheel. In the present embodiment, the disc brake units 21FR to 21RL are used, but other braking force applying mechanisms including a wheel cylinder 23 such as a drum brake may be used.

  In this embodiment, the master cylinder unit 27 is a master cylinder with a hydraulic booster, and includes a hydraulic booster 31, a master cylinder 32, a regulator 33, and a reservoir. The hydraulic booster 31 is connected to the brake pedal 24, amplifies the pedal effort applied to the brake pedal 24, and transmits it to the master cylinder 32. When the brake fluid is supplied from the power hydraulic pressure source 30 to the hydraulic pressure booster 31 via the regulator 33, the pedal effort is amplified. The master cylinder 32 generates a master cylinder pressure having a predetermined boost ratio with respect to the pedal effort.

  A reservoir 34 for storing brake fluid is disposed above the master cylinder 32 and the regulator 33. The master cylinder 32 communicates with the reservoir 34 when the depression of the brake pedal 24 is released. On the other hand, the regulator 33 is in communication with both the reservoir 34 and the accumulator 35 of the power hydraulic pressure source 30, and the reservoir 34 is used as a low pressure source, the accumulator 35 is used as a high pressure source, and the hydraulic pressure is approximately equal to the master cylinder pressure. Is generated. Hereinafter, the hydraulic pressure in the regulator 33 is appropriately referred to as “regulator pressure”. The master cylinder pressure and the regulator pressure do not need to be exactly the same pressure. For example, the master cylinder unit 27 can be designed so that the regulator pressure is slightly higher.

  The power hydraulic pressure source 30 includes an accumulator 35 and a pump 36. The accumulator 35 converts the pressure energy of the brake fluid boosted by the pump 36 into the pressure energy of an enclosed gas such as nitrogen, for example, about 14 to 22 MPa and stores it. The pump 36 has a motor 36 a as a drive source, and its suction port is connected to the reservoir 34, while its discharge port is connected to the accumulator 35. The accumulator 35 is also connected to a relief valve 35 a provided in the master cylinder unit 27. When the pressure of the brake fluid in the accumulator 35 increases abnormally to about 25 MPa, for example, the relief valve 35 a is opened, and the high-pressure brake fluid is returned to the reservoir 34.

  As described above, the hydraulic brake unit 20 includes the master cylinder 32, the regulator 33, and the accumulator 35 as a supply source of brake fluid to the wheel cylinder 23. A master pipe 37 is connected to the master cylinder 32, a regulator pipe 38 is connected to the regulator 33, and an accumulator pipe 39 is connected to the accumulator 35. These master pipe 37, regulator pipe 38 and accumulator pipe 39 are each connected to a hydraulic actuator 40.

  The hydraulic actuator 40 includes an actuator block in which a plurality of flow paths are formed, and a plurality of electromagnetic control valves. The flow paths formed in the actuator block include individual flow paths 41, 42, 43 and 44 and a main flow path 45. The individual flow paths 41 to 44 are respectively branched from the main flow path 45 and connected to the wheel cylinders 23FR, 23FL, 23RR, 23RL of the corresponding disc brake units 21FR, 21FL, 21RR, 21RL. Thereby, each wheel cylinder 23 can communicate with the main flow path 45.

  In addition, ABS holding valves 51, 52, 53 and 54 are provided in the middle of the individual flow paths 41, 42, 43 and 44. Each of the ABS holding valves 51 to 54 has a solenoid and a spring that are ON / OFF controlled, and both are normally open electromagnetic control valves that are opened when the solenoid is in a non-energized state. Each of the ABS holding valves 51 to 54 in the opened state can distribute the brake fluid in both directions. That is, the brake fluid can flow from the main flow path 45 to the wheel cylinder 23, and conversely, the brake fluid can also flow from the wheel cylinder 23 to the main flow path 45. When the solenoid is energized and the ABS holding valves 51 to 54 are closed, the flow of brake fluid in the individual flow paths 41 to 44 is blocked.

  Further, the wheel cylinder 23 is connected to the reservoir channel 55 via pressure reducing channels 46, 47, 48 and 49 connected to the individual channels 41 to 44, respectively. ABS decompression valves 56, 57, 58 and 59 are provided in the middle of the decompression channels 46, 47, 48 and 49. Each of the ABS pressure reducing valves 56 to 59 has a solenoid and a spring that are ON / OFF controlled, and is a normally closed electromagnetic control valve that is closed when the solenoid is in a non-energized state. When the ABS pressure reducing valves 56 to 59 are closed, the flow of brake fluid in the pressure reducing flow paths 46 to 49 is blocked. When the solenoid is energized and the ABS pressure reducing valves 56 to 59 are opened, the brake fluid is allowed to flow through the pressure reducing flow paths 46 to 49, and the brake fluid flows from the wheel cylinder 23 to the pressure reducing flow paths 46 to 49 and It returns to the reservoir 34 via the reservoir channel 55. The reservoir channel 55 is connected to the reservoir 34 of the master cylinder unit 27 via a reservoir pipe 77.

  The main channel 45 has a separation valve 60 in the middle. By this separation valve 60, the main channel 45 is divided into a first channel 45 a connected to the individual channels 41 and 42 and a second channel 45 b connected to the individual channels 43 and 44. The first flow path 45a is connected to the front wheel wheel cylinders 23FR and 23FL via the individual flow paths 41 and 42, and the second flow path 45b is connected to the rear wheel wheel cylinder via the individual flow paths 43 and 44. Connected to 23RR and 23RL.

  The separation valve 60 has a solenoid and a spring that are ON / OFF controlled, and is a normally closed electromagnetic control valve that is closed when the solenoid is in a non-energized state. When the separation valve 60 is in the closed state, the flow of brake fluid in the main flow path 45 is blocked. When the solenoid is energized and the separation valve 60 is opened, the brake fluid can be circulated bidirectionally between the first flow path 45a and the second flow path 45b.

  In the hydraulic actuator 40, a master channel 61 and a regulator channel 62 communicating with the main channel 45 are formed. More specifically, the master channel 61 is connected to the first channel 45 a of the main channel 45, and the regulator channel 62 is connected to the second channel 45 b of the main channel 45. The master channel 61 is connected to a master pipe 37 that communicates with the master cylinder 32. The regulator channel 62 is connected to a regulator pipe 38 that communicates with the regulator 33.

  The master channel 61 has a master cut valve 64 in the middle. The master cut valve 64 is provided on the brake fluid supply path from the master cylinder 32 to each wheel cylinder 23. The master cut valve 64 has a solenoid and a spring that are ON / OFF-controlled, and the valve closing state is guaranteed by the electromagnetic force generated by the solenoid when supplied with a prescribed control current, so that the solenoid is in a non-energized state. It is a normally open electromagnetic control valve that is opened in some cases. The master cut valve 64 in the opened state can cause the brake fluid to flow in both directions between the master cylinder 32 and the first flow path 45 a of the main flow path 45. When a prescribed control current is applied to the solenoid and the master cut valve 64 is closed, the flow of brake fluid in the master flow path 61 is interrupted.

  A stroke simulator 69 is connected to the master channel 61 via a simulator cut valve 68 on the upstream side of the master cut valve 64. That is, the simulator cut valve 68 is provided in a flow path connecting the master cylinder 32 and the stroke simulator 69. The simulator cut valve 68 has a solenoid and a spring that are ON / OFF controlled, and the valve opening state is guaranteed by the electromagnetic force generated by the solenoid upon receipt of a specified control current, and the solenoid is in a non-energized state. It is a normally closed electromagnetic control valve that is closed in some cases. When the simulator cut valve 68 is closed, the flow of brake fluid between the master flow path 61 and the stroke simulator 69 is blocked. When the solenoid is energized and the simulator cut valve 68 is opened, the brake fluid can be circulated bidirectionally between the master cylinder 32 and the stroke simulator 69.

  The stroke simulator 69 includes a plurality of pistons and springs, and creates a reaction force corresponding to the depression force of the brake pedal 24 by the driver when the simulator cut valve 68 is opened. As the stroke simulator 69, in order to improve the feeling of brake operation by the driver, it is preferable to employ one having a multistage spring characteristic.

  The regulator flow path 62 has a regulator cut valve 65 in the middle. The regulator cut valve 65 is provided on the brake fluid supply path from the regulator 33 to each wheel cylinder 23. The regulator cut valve 65 also has a solenoid and a spring that are ON / OFF controlled, and the valve closing state is guaranteed by the electromagnetic force generated by the solenoid upon receipt of a specified control current, and the solenoid is in a non-energized state. It is a normally open electromagnetic control valve that is opened in some cases. The regulator cut valve 65 that has been opened can cause the brake fluid to flow in both directions between the regulator 33 and the second flow path 45 b of the main flow path 45. When the solenoid is energized and the regulator cut valve 65 is closed, the flow of brake fluid in the regulator flow path 62 is blocked.

  In the hydraulic actuator 40, an accumulator channel 63 is also formed in addition to the master channel 61 and the regulator channel 62. One end of the accumulator channel 63 is connected to the second channel 45 b of the main channel 45, and the other end is connected to an accumulator pipe 39 that communicates with the accumulator 35.

  The accumulator flow path 63 has a pressure-increasing linear control valve 66 in the middle. Further, the accumulator channel 63 and the second channel 45 b of the main channel 45 are connected to the reservoir channel 55 via the pressure-reducing linear control valve 67. The pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 each have a linear solenoid and a spring, and both are normally closed electromagnetic control valves that are closed when the solenoid is in a non-energized state. In the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67, the opening degree of the valve is adjusted in proportion to the current supplied to each solenoid.

  The pressure-increasing linear control valve 66 is provided as a common pressure-increasing control valve for each of the wheel cylinders 23 provided corresponding to each wheel. Similarly, the pressure-reducing linear control valve 67 is provided as a pressure-reducing control valve common to the wheel cylinders 23. That is, in this embodiment, the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67 are a pair of common control valves that control the supply and discharge of the working fluid sent from the power hydraulic pressure source 30 to each wheel cylinder 23. It is provided as. Thus, if the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 are made common to each wheel cylinder 23, it is preferable from the viewpoint of cost as compared with the case where a linear control valve is provided for each wheel cylinder 23.

  Here, the differential pressure between the inlet and outlet of the pressure-increasing linear control valve 66 corresponds to the differential pressure between the pressure of the brake fluid in the accumulator 35 and the pressure of the brake fluid in the main flow path 45, and the inlet / outlet of the pressure-reducing linear control valve 67. The pressure difference therebetween corresponds to the pressure difference between the brake fluid pressure in the main flow path 45 and the brake fluid pressure in the reservoir 34. Further, the electromagnetic driving force according to the power supplied to the linear solenoid of the pressure increasing linear control valve 66 and the pressure reducing linear control valve 67 is F1, the spring biasing force is F2, and the pressure increasing linear control valve 66 and the pressure reducing linear control valve are Assuming that the differential pressure acting force according to the differential pressure between the inlet / outlet of 67 is F3, the relationship of F1 + F3 = F2 is established. Therefore, the differential pressure between the inlet and outlet of the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67 is controlled by continuously controlling the power supplied to the linear solenoids of the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67. can do.

  In the hydraulic brake unit 20, the power hydraulic pressure source 30 and the hydraulic actuator 40 are controlled by a brake ECU 70 as a control unit in the present embodiment. The brake ECU 70 is configured as a microprocessor including a CPU, and includes a ROM that stores various programs, a RAM that temporarily stores data, an input / output port, a communication port, and the like in addition to the CPU. The brake ECU 70 can communicate with the host hybrid ECU 7 and the like, and configures the pump 36 of the power hydraulic pressure source 30 and the hydraulic actuator 40 based on control signals from the hybrid ECU 7 and signals from various sensors. The electromagnetic control valves 51 to 54, 56 to 59, 60, and 64 to 68 are controlled.

  Further, a regulator pressure sensor 71, an accumulator pressure sensor 72, and a control pressure sensor 73 are connected to the brake ECU 70. The regulator pressure sensor 71 detects the pressure of the brake fluid in the regulator flow path 62 on the upstream side of the regulator cut valve 65, that is, the regulator pressure, and gives a signal indicating the detected value to the brake ECU 70. The accumulator pressure sensor 72 detects the pressure of the brake fluid in the accumulator flow path 63, that is, the accumulator pressure on the upstream side of the pressure increasing linear control valve 66, and gives a signal indicating the detected value to the brake ECU 70. The control pressure sensor 73 detects the pressure of the brake fluid in the first flow path 45a of the main flow path 45, and gives a signal indicating the detected value to the brake ECU 70. The detection values of the pressure sensors 71 to 73 are sequentially given to the brake ECU 70 every predetermined time, and are stored and held in a predetermined storage area of the brake ECU 70.

  When the separation valve 60 is opened and the first flow path 45 a and the second flow path 45 b of the main flow path 45 communicate with each other, the output value of the control pressure sensor 73 is the low pressure of the pressure-increasing linear control valve 66. This indicates the hydraulic pressure on the high pressure side of the pressure-reducing linear control valve 67 and the output value can be used to control the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67. When the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 are closed and the master cut valve 64 is opened, the output value of the control pressure sensor 73 indicates the master cylinder pressure. Further, the separation valve 60 is opened so that the first flow path 45a and the second flow path 45b of the main flow path 45 communicate with each other, and the ABS holding valves 51 to 54 are opened, while the ABS pressure reducing valves 56 are opened. When? 59 is closed, the output value of the control pressure sensor 73 indicates the working fluid pressure acting on each wheel cylinder 23, i.e., the wheel cylinder pressure.

  Further, the sensor connected to the brake ECU 70 includes a stroke sensor 25 provided on the brake pedal 24. The stroke sensor 25 detects a pedal stroke as an operation amount of the brake pedal 24 and gives a signal indicating the detected value to the brake ECU 70. The output value of the stroke sensor 25 is also sequentially given to the brake ECU 70 every predetermined time, and is stored and held in a predetermined storage area of the brake ECU 70. A brake operation state detection unit other than the stroke sensor 25 may be provided in addition to the stroke sensor 25 or in place of the stroke sensor 25 and connected to the brake ECU 70. Examples of the brake operation state detection means include a pedal depression force sensor that detects an operation force of the brake pedal 24 and a brake switch that detects that the brake pedal 24 is depressed.

  The brake control device according to the present embodiment including the hydraulic brake unit 20 configured as described above can execute brake regeneration cooperative control. The brake control device starts braking upon receiving a braking request. The braking request is generated when a braking force should be applied to the vehicle, for example, when the driver operates the brake pedal 24. In response to the braking request, the brake ECU 70 calculates a required braking force, and calculates a required hydraulic braking force that is a braking force that should be generated by the hydraulic brake unit 20 by subtracting the regenerative braking force from the required braking force. Here, the output value of the regenerative braking force is supplied from the hybrid ECU 7 to the brake ECU 70. Then, the brake ECU 70 calculates the target hydraulic pressure of each wheel cylinder 23FR to 23RL based on the calculated required hydraulic braking force. The brake ECU 70 determines the value of the control current supplied to the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 by feedback control so that the wheel cylinder pressure becomes the target hydraulic pressure.

  As a result, in the hydraulic brake unit 20, the brake fluid is supplied from the power hydraulic pressure source 30 to each wheel cylinder 23 via the pressure-increasing linear control valve 66, and braking force is applied to the wheels. Further, brake fluid is discharged from each wheel cylinder 23 through the pressure-reducing linear control valve 67 as necessary, and the braking force applied to the wheel is adjusted. In the present embodiment, a wheel cylinder pressure control system is configured including the power hydraulic pressure source 30, the pressure-increasing linear control valve 66, the pressure-decreasing linear control valve 67, and the like. A so-called brake-by-wire braking force control is performed by the wheel cylinder pressure control system. The wheel cylinder pressure control system is provided in parallel to the brake fluid supply path from the master cylinder unit 27 to the wheel cylinder 23.

  When brake-by-wire braking force control is performed, the brake ECU 70 closes the regulator cut valve 65 so that the brake fluid delivered from the regulator 33 is not supplied to the wheel cylinder 23. Further, the brake ECU 70 closes the master cut valve 64 and opens the simulator cut valve 68. This is because the brake fluid sent from the master cylinder 32 in accordance with the operation of the brake pedal 24 by the driver is supplied not to the wheel cylinder 23 but to the stroke simulator 69. During the brake regeneration cooperative control, a differential pressure corresponding to the magnitude of the regenerative braking force acts between the upstream and downstream of the regulator cut valve 65 and the master cut valve 64. The brake ECU 70 opens the separation valve 60. Thereby, each wheel cylinder pressure is controlled to a common hydraulic pressure.

  The hydraulic brake unit 20 according to the present embodiment can naturally control the braking force by the wheel cylinder pressure control system even when the required braking force is provided only by the hydraulic braking force without using the regenerative braking force. it can. Regardless of whether or not the brake regeneration cooperative control is executed, the control mode for controlling the braking force by the wheel cylinder pressure control system will be appropriately referred to as a “linear control mode” below. Or it may be called control by brake-by-wire.

  In the linear control mode, the hydraulic brake unit 20 generates, for example, a braking force required by the driver, for example, a so-called ABS (SBS) for suppressing the slip of each wheel with respect to the road surface and stabilizing the behavior of the vehicle. Anti-lock break system (VSC) control, VSC (Vehicle Stability Control) control, TRC (Traction Control) control, and the like can be executed. The ABS control is a control for suppressing tire locking that occurs when braking is applied suddenly or on a slippery road surface. VSC control is control for suppressing the side slip of the wheel at the time of turning of the vehicle. The TRC control is a control for suppressing idling of the drive wheels when the vehicle starts or accelerates.

  The brake ECU 70 executes the above-described ABS control and the like as necessary based on the input from each sensor in the linear control mode. The brake ECU 70 opens and closes the ABS holding valves 51 to 54 and the ABS pressure reducing valves 56 to 59 individually and repeatedly at a predetermined duty ratio calculated by a known method based on the vehicle deceleration, the slip ratio, and the like. When the ABS holding valves 51 to 54 are in an open state, the brake fluid is adjusted by a pressure increasing linear control valve 66 and a pressure reducing linear control valve 67 which are common control valves provided upstream of the ABS holding valves 51 to 54. Is supplied to each wheel cylinder 23. Further, when the ABS pressure reducing valves 56 to 59 are in the open state, the brake fluid of each wheel cylinder 23 is discharged to the reservoir 34. Thus, the brake fluid is individually supplied to and discharged from each wheel cylinder 23, and the braking force applied to each wheel is controlled so that the slippage of the wheel is suppressed.

  Further, when the required braking force is generated only by the hydraulic braking force in the linear control mode, the brake ECU 70 controls the regulator pressure or the master cylinder pressure as the target pressure of the wheel cylinder pressure. Therefore, in this case, it is not always necessary to supply the brake fluid to the wheel cylinder 23 by the wheel cylinder pressure control system. This is because the required braking force can be generated naturally if the master cylinder pressure or the regulator pressure pressurized according to the operation of the brake pedal by the driver is directly introduced into the wheel cylinder.

  For this reason, the hydraulic brake unit 20 may supply brake fluid from the regulator 33 to each wheel cylinder 23 when the regenerative braking force is not used, for example, when the vehicle is stopped. Hereinafter, the control mode in which the brake fluid is supplied from the regulator 33 to each wheel cylinder 23 is referred to as a regulator mode. That is, the brake ECU 70 may switch from the linear control mode to the regulator mode while the vehicle is stopped to generate a braking force. If the control mode is switched when the vehicle is stopped, it is preferable in that the control mode can be switched with relatively simple control. Alternatively, more practically, the brake ECU 70 may switch the control mode from the linear control mode to the regulator mode when the regenerative braking is stopped because the vehicle speed has sufficiently decreased due to braking.

  In the regulator mode, the brake ECU 70 opens the regulator cut valve 65 and the separation valve 60 and closes the master cut valve 64. The pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 are stopped and closed. The simulator cut valve 68 is opened. As a result, brake fluid is supplied from the regulator 33 to each wheel cylinder 23, and braking force is applied to each wheel by the regulator pressure. Since the power hydraulic pressure source 30 is connected to the regulator 33 on the high pressure side, it is preferable in that the braking force can be generated by utilizing the accumulated pressure in the power hydraulic pressure source 30.

  Thus, in the regulator mode, the brake ECU 70 stops supplying the control current to the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 and closes both linear control valves. For this reason, it becomes possible to reduce the operation frequency of the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67, and the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67 can be used for a long period of time. . That is, the durability of the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 can be improved.

  Further, during the control in the linear control mode, the wheel cylinder pressure may deviate from the target hydraulic pressure due to, for example, occurrence of an abnormality such as leakage of hydraulic fluid from any location. The brake ECU 70 periodically determines the presence or absence of a wheel cylinder pressure response abnormality based on, for example, a measurement value of the control pressure sensor 73. The brake ECU 70 determines that there is an abnormality in the control response of the wheel cylinder pressure when, for example, the amount of deviation of the measured value of the wheel cylinder pressure from the target hydraulic pressure exceeds the reference. When it is determined that the wheel cylinder pressure control response is abnormal, the brake ECU 70 stops the linear control mode and switches the control mode to the manual brake mode. Similarly, in the regulator mode, the brake ECU 70 switches the control mode to the manual brake mode when an abnormality is detected. In the manual brake mode, the driver's input to the brake pedal 24 is converted into hydraulic pressure and mechanically transmitted to the wheel cylinder 23 to apply braking force to the wheels. The manual brake mode serves as a backup brake control mode for the linear control mode from the viewpoint of fail-safe.

  The brake ECU 70 can select one of a plurality of modes as the manual brake mode by changing the hydraulic pressure source and the supply path from the hydraulic pressure source to the wheel cylinder 23. In this embodiment, the transition to the hydro booster mode will be described as an example. In the hydro booster mode, the brake ECU 70 stops supplying control current to all the electromagnetic control valves. Therefore, the normally open master cut valve 64 and the regulator cut valve 65 are opened, and the normally closed separation valve 60 and the simulator cut valve 68 are closed. The pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 are stopped and closed.

  As a result, the brake fluid supply path is separated into two systems, the master cylinder side and the regulator side. The master cylinder pressure is transmitted to the front wheel wheel cylinders 23FR and 23FL, and the regulator pressure is transmitted to the rear wheel wheel cylinders 23RR and 23RL. The destination of the working fluid from the master cylinder 32 is switched from the stroke simulator 69 to the wheel cylinders 23FR and 23FL for the front wheels. Further, since the hydraulic booster 31 is a mechanism that mechanically amplifies the pedal depression force, the hydraulic booster 31 continues to function even when the control current to each electromagnetic control valve is stopped by shifting to the hydro booster mode. According to the hydro booster mode, even if there is no energization to each electromagnetic control valve due to an abnormality in the control system, it is excellent in fail-safety in that braking force can be generated using a hydraulic booster. Yes.

  For convenience, the system on the master cylinder side in the hydro booster mode is hereinafter referred to as a master system, and the system on the regulator side is referred to as a regulator system. In the present embodiment, in the hydro booster mode, the hydraulic fluid is supplied to the front wheel side by the master system and to the rear wheel side by the regulator system. . In the hydro booster mode, it is not essential that the master system supplies hydraulic fluid to the front wheel side and the regulator system supplies hydraulic fluid to the rear wheel side. For example, the master system supplies hydraulic fluid to the right front wheel and the left rear wheel, and the regulator system supplies hydraulic fluid to the left front wheel and the right rear wheel, for example, so-called X in which the left and right wheels are connected to separate systems. A pipe-type brake control device may be used.

  As described above, in the present embodiment, when the brake system is normal, usually, the regenerative braking force is preferentially used and the hydraulic braking force is complementarily used to generate the required braking force. The brake ECU 70 shifts to the hydro booster mode as described above when an abnormality is detected in the system. At this time, regenerative assist control may be executed in which the regenerative braking force is supplementarily added to the hydraulic braking force corresponding to the driver's brake operation. In the present embodiment, the brake ECU 70 performs regeneration assist control when, for example, an abnormality is detected in the front system, and performs normal assistance without performing regeneration assist control when an abnormality is detected in other than the front system. Run booster mode. In addition, you may perform regeneration assistance control, when abnormality is detected other than a front system | strain.

  FIG. 3 is a flowchart for explaining the regeneration assist control according to the present embodiment. FIG. 3 shows an example of the regeneration assist control. The process shown in FIG. 3 is periodically executed by the brake ECU 70 when an abnormality is detected in the front system and the mode is shifted to the hydro booster mode. In this embodiment, the regeneration assist control is executed when an abnormality is detected in the front system. However, even if the regeneration assist control is performed when an abnormality is detected in the rear system or other places. Good. Further, the regeneration assist control may be executed during execution of a brake control mode other than the hydro booster mode.

  In the regeneration assist control, as shown in FIG. 3, the brake ECU 70 first selects a deceleration map for calculating the target deceleration (S10). The brake ECU 70 acquires a plurality of deceleration maps in advance, and calculates a target deceleration based on one of the deceleration maps. The deceleration map shows the relationship between the sensor measurement value that reflects the driver's brake operation amount and the target deceleration. The hydraulic brake unit 20 according to the present embodiment includes a plurality of sensors, and a deceleration map for each sensor is stored in the brake ECU 70 in advance. In addition, a deceleration map for calculating a target deceleration using measured values of a plurality of sensors may be stored in the brake ECU 70 in advance.

  The brake ECU 70 calculates the target deceleration based on the selected deceleration map and the sensor measurement value required as an input in the selected deceleration map (S12). The brake ECU 70 calculates the required value of the regenerative braking force by subtracting the hydraulic braking force from the calculated target deceleration (S14). That is, the regenerative braking force that should be generated in an auxiliary manner is calculated by subtracting the actually generated hydraulic braking force from the target deceleration. The brake ECU 70 calculates the hydraulic braking force in the master system based on the measured hydraulic pressure of the control pressure sensor 73, and calculates the hydraulic braking force in the regulator system based on the measured hydraulic pressure of the regulator pressure sensor 71. The brake ECU 70 outputs the obtained regenerative braking force request value to the hybrid ECU 7 (S16). In response to this, the hybrid ECU 7 determines whether or not the regenerative braking force exceeding the required value can be generated based on, for example, the state of charge of the battery 12. The hybrid ECU 7 generates a regenerative braking force equal to the required value if the regenerative braking force exceeding the required value can be generated. On the contrary, if only the regenerative braking force that does not satisfy the required value can be generated, the hybrid ECU 7 generates the maximum regenerative braking force in that state.

  Specifically, the brake ECU 70 has a deceleration map for calculating the target deceleration based only on the measurement stroke of the stroke sensor 25, for example. Further, the brake ECU 70 calculates the target deceleration based only on the deceleration map for calculating the target deceleration based only on the measured regulator pressure of the regulator pressure sensor 71 and the measured control hydraulic pressure of the control pressure sensor 73. Have a deceleration map for Furthermore, you may have a deceleration map for calculating a target deceleration based on the measured value of two or more sensors, the stroke sensor 25, the regulator pressure sensor 71, and the control pressure sensor 73. FIG.

  Even if the deceleration map in the regenerative assist control is adjusted so that the target deceleration in the regenerative assist control takes a larger value for the same brake operation amount than the target deceleration in the normal regenerative cooperative control. Good. In regenerative cooperative control, the braking force is controlled so as to achieve the target deceleration calculated according to the amount of brake operation, whereas the target deceleration in regenerative assist control is used to calculate the regenerative braking force request value. This is because it is only used. The target deceleration in the regeneration assist control may not reflect the driver's brake operation amount more strictly than the regeneration cooperative control. By making the target deceleration higher in the regenerative assist control, it becomes easier to generate a larger regenerative braking force as an assist. In the present embodiment, the regeneration assist control is basically executed when an abnormality of the hydraulic brake unit 20 is detected. Therefore, it is possible to easily ensure a sufficient braking force by assisting the hydraulic braking force reduced due to the abnormality with a large regenerative braking force.

  Therefore, from the viewpoint of securing the braking force, it is desirable that the brake ECU 70 selects a deceleration map that gives the maximum target deceleration, that is, the maximum regenerative braking force requirement value, among the plurality of deceleration maps. In this case, the brake ECU 70 first calculates a target deceleration for all of the plurality of deceleration maps. Then, the brake ECU 70 selects the maximum one of the calculated target decelerations, and calculates the regenerative braking force request value using the maximum target deceleration. Further, at this time, the brake ECU 70 may compare the obtained maximum target deceleration with the target deceleration used in the normal state, and use the larger one as the target deceleration of the regeneration assist control. . In this way, there is an advantage that the control algorithm can be simplified because it is only necessary to select the maximum target deceleration.

  Also, the brake ECU 70 selects a sensor that is determined to have the highest reliability of the measurement value, and calculates the target deceleration or the regenerative braking force request value based on the deceleration map corresponding to the selected sensor. Good. Alternatively, the brake ECU 70 excludes the deceleration map corresponding to the sensor that is determined to have low measurement value reliability, and selects one of the remaining deceleration maps to obtain the target deceleration or regenerative braking force request value. You may calculate. At this time, the brake ECU 70 may select a deceleration map that gives the maximum target deceleration, that is, the maximum regenerative braking force request value, from the remaining deceleration maps for which reliability is ensured. In this way, good brake controllability can be obtained by adding the reliability of the sensor measurement value.

  For example, when the hydraulic fluid leaks in the master system, it cannot be said that the measured value of the control pressure sensor 73 reflects the brake operation amount of the driver, and the reliability is low. Therefore, in this case, for example, the brake ECU 70 calculates the target deceleration based on a deceleration map that receives the measured value of the regulator pressure sensor 71 or a deceleration map that receives the measured value of the stroke sensor 25. For example, when liquid leakage occurs in the regulator system, the reliability of the measured value of the regulator pressure sensor 71 is low. Therefore, for example, the brake ECU 70 calculates the target deceleration based on a deceleration map that receives the measured value of the control pressure sensor 73 or a deceleration map that receives the measured value of the stroke sensor 25. Alternatively, there may be an abnormality in the sensor itself. In this case, the brake ECU 70 calculates the target deceleration based on the deceleration map that receives the measured value of the normal sensor.

  Incidentally, in general, the brake ECU 70 may stop the regenerative cooperative control or the regenerative assist control when the above-described ABS control is being performed on a specific wheel. This is because it is considered that high rotation due to wheel slip causes a large regenerative current. This large current may adversely affect the battery. However, in the present embodiment, the brake ECU 70 may continue the regeneration assist control when the ABS control is performed during the regeneration assist control. The brake ECU 70 continues to apply the regenerative braking force to the wheels for which the ABS control is not executed when there is a wheel for which the ABS control is not executed when the ABS control is executed for at least one wheel. . In the present embodiment, the regenerative braking force can be applied only to the front wheels that are drive wheels. Therefore, for example, the brake ECU 70 continues to apply the regenerative braking force to the front wheels when the ABS control is being performed on the rear wheels. This helps to ensure a sufficient braking force.

  Further, the brake ECU 70 may continue to apply the regenerative braking force to the system in which an abnormality has occurred when the ABS control is executed in the system in which no abnormality has occurred. In the present embodiment, for example, when the front wheel is leaking and the rear wheel is performing the ABS control, the regenerative braking force is continuously applied to the front wheel. In this way, it is possible to ensure a sufficient braking force.

  In addition, when the ABS control is being executed, it is desirable that the brake ECU 70 additionally execute a process for reducing the influence of fluctuations in the hydraulic pressure measurement value due to the ABS control on the target deceleration of the regeneration assist control. . By reducing the influence of sudden increase / decrease in the hydraulic pressure due to ABS control, the brake controllability in the regeneration assist control is improved.

  For example, when the ABS control is being executed, the brake ECU 70 performs a filter process so as to reduce fluctuations in the measured value of the hydraulic pressure sensor, and uses the measured value for calculating the target deceleration or the regenerative braking force request value. May be. In the present embodiment, for example, the brake ECU 70 applies a low-pass filter to the measured value of the regulator pressure sensor 71 when the ABS control is being executed on the rear wheel, and uses the measured value after the filtering process for calculating the regenerative braking force request value. . The characteristics of the low-pass filter are preferably set as appropriate so as to remove or reduce the hydraulic pressure fluctuation caused by the ABS control. In this way, when the regulator pressure is used to calculate the regenerative braking force request value, it is possible to suppress the influence of the sudden fluctuation of the regulator pressure due to the ABS control. As a result, the pulsation of the regenerative braking force that can occur in response to the ABS control can be suppressed, and the regenerative braking force can be output stably.

  Further, the brake ECU 70 may perform a guard process on the target deceleration or the sudden decrease in the regenerative braking force request value when the ABS control is being executed in the regeneration assist control. For example, when the ABS control is being executed, the brake ECU 70 suppresses fluctuations in the regenerative braking force request value when the measured value decreases compared to when the measured value of the hydraulic pressure sensor increases. May be. In the present embodiment, for example, the brake ECU 70 allows an increase in the regenerative braking force request value when the measured value of the regulator pressure sensor 71 is increasing when the ABS control is being executed in the rear system, and the measured value When is decreasing, the reduction of the regenerative braking force request value is limited. In this way, the influence of the sudden decrease in hydraulic pressure due to the ABS control on the regenerative braking force request value can be reduced, which contributes to securing the regenerative braking force in the regenerative assist control.

  Next, the abnormal location specifying process according to the present embodiment will be described. The brake ECU 70 executes the abnormality location specifying process when the above-described hydraulic pressure response abnormality is detected. In the present embodiment, the brake ECU 70 identifies the location where the abnormality has occurred or the content of the abnormality that has occurred using the measured values of the stroke sensor 25, the regulator pressure sensor 71, and the control pressure sensor 73. For example, the brake ECU 70 specifies whether an abnormality has occurred in the master system or the regulator system based on the measured values of the sensors. In addition, the brake ECU 70 may specify which of the measured values of the stroke sensor 25, the regulator pressure sensor 71, and the control pressure sensor 73 is highly reliable. In other words, the brake ECU 70 may determine whether an abnormality has occurred in any of the stroke sensor 25, the regulator pressure sensor 71, or the control pressure sensor 73. In this embodiment, since it is considered that the possibility of an abnormality occurring at two or more locations at the same time is extremely low, if an abnormality is detected, an abnormality has occurred at any one location in the brake control device. To do.

  FIG. 4 is a graph for explaining an example of the abnormal part specifying process according to the present embodiment. The vertical axis in FIG. 4 is the measured value of the control pressure sensor 73, and the horizontal axis is the measured value of the regulator pressure sensor 71. The brake ECU 70 identifies the location where the abnormality has occurred depending on which of the plurality of regions set on the graph shown in FIG. 4 includes the measurement values of the control pressure sensor 73 and the regulator pressure sensor 71. Regions M1 to M3 shown in FIG. 4 are preset and stored in the brake ECU 70.

  A region M1 indicated by a broken line in FIG. 4 is set to include a straight line m1 indicated by a solid line in FIG. For example, the region M1 is set on both sides of the straight line m1 with a predetermined distance from the straight line m1. The straight line m1 indicates the measured value of the control pressure sensor 73 and the measured value of the regulator pressure sensor 71 when there is no liquid leakage in the front system and the rear system of the hydraulic brake unit 20 and the shift to the hydro booster mode occurs due to some other abnormality. An example of a relationship with a value is shown. If no liquid leakage occurs in any of the systems, the measured value of the control pressure sensor 73 and the measured value of the regulator pressure sensor 71 are linked as shown by the straight line m1.

  Hereinafter, the lower side of the region M1 is appropriately referred to as a region M2, and the upper side of the region M1 is referred to as a region M3. In FIG. 4, the boundary between the region M1 and the region M2 and the boundary between the region M1 and the region M3 are indicated by broken lines. The region M2 is a region where the measured value of the control pressure sensor 73 is too low with respect to the measured value of the regulator pressure sensor 71. Therefore, when the measured value is included in the region M2, it can be said that liquid leakage has occurred in the front system where the control pressure sensor 73 is disposed. The region M3 is a region where the measured value of the regulator pressure sensor 71 is too low with respect to the measured value of the control pressure sensor 73. Therefore, when the measured value is included in the region M3, it can be said that liquid leakage has occurred in the rear system in which the regulator pressure sensor 71 is disposed. The straight line m2 is an example of the relationship between the measured value of the control pressure sensor 73 and the measured value of the regulator pressure sensor 71 when liquid leakage occurs in the front system. The straight line m3 is an example of the relationship between the measured value of the control pressure sensor 73 and the measured value of the regulator pressure sensor 71 when liquid leakage occurs in the rear system.

  Therefore, when the measured values of the control pressure sensor 73 and the regulator pressure sensor 71 are included in the region M2, the brake ECU 70 determines that liquid leakage has occurred in the front system, and the control pressure sensor 73 and the regulator pressure sensor 71. Is included in the region M3, it is determined that liquid leakage has occurred in the rear system. In addition, when the measured values of the control pressure sensor 73 and the regulator pressure sensor 71 are included in the region M1, the brake ECU 70 determines that an abnormality other than liquid leakage has occurred.

  FIG. 5 is a graph for explaining another example of the abnormal part specifying process according to the present embodiment. The vertical axis in FIG. 5 is the measured value of the stroke sensor 25, and the horizontal axis is the measured value of the regulator pressure sensor 71. The brake ECU 70 identifies the location where the abnormality has occurred depending on which of the plurality of regions set on the graph shown in FIG. 5 includes the measurement values of the stroke sensor 25 and the regulator pressure sensor 71. Regions N1 to N3 shown in FIG. 5 are preset and stored in the brake ECU 70.

  The region N1 is set to include the broken line n1, the region N2 is set to include the broken line n2, and the region N3 is set to include the straight line n3. The boundary between the region N1 and the region N2 is set between the broken line n1 and the broken line n2, and the boundary between the region N2 and the region N3 is set between the broken line n2 and the straight line n3. In FIG. 5, the boundaries between the regions N1 to N3 are indicated by broken lines.

  The broken line n1 indicates the measured value of the stroke sensor 25 and the measured value of the regulator pressure sensor 71 when there is no liquid leakage in the front system and the rear system of the hydraulic brake unit 20 and the shift to the hydro booster mode occurs due to some other abnormality. Is an example of the relationship. The broken line n1 has a larger stroke at the same regulator pressure than the relationship n4 between the stroke and the regulator pressure when the system is normal. This is because the hydraulic pressure supply volume is limited to the stroke simulator 69 in the normal case, whereas the hydraulic pressure supply volume is expanded to the front and rear wheel cylinders 23 in the hydro booster mode. Although the broken line n1 is shown as a broken line in FIG. 5, this is merely a characteristic, and in practice, a curved line whose gradient gradually decreases as the regulator pressure increases is drawn. This is because at the beginning of the pressure increase with a small stroke value, the pressure increase is absorbed to some extent due to elastic deformation of the brake fluid piping or the like, so that it is relatively difficult to increase the pressure.

  The polygonal line n2 is an example of the relationship between the measured value of the stroke sensor 25 and the measured value of the regulator pressure sensor 71 when liquid leakage occurs in the front system. When liquid leakage occurs in the front system, the increase in the regulator pressure is small with respect to the increase in stroke until the stroke amount corresponding to the front system is exceeded. When the stroke amount corresponding to the front system is depressed, the regulator pressure is increased greatly according to the stroke amount. In FIG. 5, the slope of the broken line n2 changes at the break point P. When the stroke is smaller than the break point P, the increase rate of the regulator pressure with respect to the stroke is small, and when the stroke is larger than the break point P, the increase rate of the regulator pressure with respect to the stroke becomes large.

  The straight line n3 is an example of the relationship between the measured value of the stroke sensor 25 and the measured value of the regulator pressure sensor 71 when liquid leakage occurs in the rear system. When liquid leakage occurs in the rear system, as shown in the figure, the regulator pressure hardly increases even if the stroke increases.

  Therefore, the brake ECU 70 determines that liquid leakage has occurred in the front system when the measured stroke and regulator pressure are included in the region N2. The brake ECU 70 determines that liquid leakage has occurred in the rear system when the measured stroke and regulator pressure are included in the region N3. Further, the brake ECU 70 determines that an abnormality other than liquid leakage has occurred when the measured stroke and regulator pressure are included in the region N1.

  It should be noted that a portion having a stroke smaller than the break point P in the broken line n2 may almost overlap with the straight line n3. In this case, the brake ECU 70 determines that liquid leakage has occurred in the front system when the relationship between the measured stroke and the regulator pressure has a break point P, and when there is no break point P, It may be determined that liquid leakage has occurred in the rear system.

  By the way, even when an abnormality occurs in the regulator pressure sensor 71, it is possible that the regulator pressure does not substantially change as the stroke increases or decreases as shown by the straight line n3. Therefore, when the measured stroke and the regulator pressure are included in the region N3, there is a possibility that an abnormality has occurred in the regulator pressure sensor 71, not a liquid leakage in the rear system. . In this embodiment, the stroke sensor 25 has a plurality of output systems, and has a self-diagnosis function that determines whether or not an abnormality has occurred in the sensor by comparing outputs from the plurality of output systems. Therefore, even if an abnormality occurs in the stroke sensor 25, it can be detected by self-diagnosis, so that it is not confused with an abnormality in another part.

  Therefore, the brake ECU 70 may determine an abnormality of the regulator pressure sensor 71 by executing an abnormality location specifying process described below. FIG. 6 is a flowchart for explaining an example of the abnormal part specifying process according to the present embodiment. The process shown in FIG. 6 is executed, for example, when it is determined that the measured stroke and regulator pressure are included in the region N2 or the region N3.

  When the process shown in FIG. 6 is started, the brake ECU 70 determines whether or not the hydraulic pressure in the accumulator 35 has decreased (S20). The brake ECU 70 determines whether or not the accumulator pressure has decreased based on the measurement value of the accumulator pressure sensor 72. For example, the brake ECU 70 determines that the accumulator pressure is reduced when the accumulator pressure falls below a predetermined determination threshold value or exceeds a predetermined pressure reduction gradient and the accumulator pressure is reduced. If it is determined that the accumulator pressure has decreased (Yes in S20), the brake ECU 70 determines that liquid leakage has occurred in the rear system (S22). This is because the detected decrease in accumulator pressure is considered to be caused by liquid leakage from the rear system.

  On the other hand, when it is determined that the accumulator pressure has not decreased (No in S20), the brake ECU 70 determines whether or not the break point P is detected in the relationship between the measured stroke and the regulator pressure. (S24). When the break point P is detected (Yes in S24), the brake ECU 70 determines that liquid leakage has occurred in the front system as described above (S26). Conversely, when the break point P is not detected (No in S24), the brake ECU 70 determines that the regulator pressure sensor 71 is abnormal (S28). In this way, it is possible to distinguish between the case where liquid leakage occurs in the front system and the rear system and the case where abnormality occurs in the regulator pressure sensor 71.

  FIG. 7 is a graph for explaining another example of the abnormal part specifying process according to the present embodiment. The vertical axis in FIG. 7 is the measurement value of the stroke sensor 25, and the horizontal axis is the measurement value of the control pressure sensor 73. In the hydro booster mode, the measured value of the control pressure sensor 73 indicates the master cylinder pressure. The brake ECU 70 identifies the location where the abnormality has occurred depending on which of the plurality of regions set on the graph shown in FIG. 7 includes the measurement values of the stroke sensor 25 and the control pressure sensor 73. Regions Q1 and Q2 shown in FIG. 7 are preset and stored in the brake ECU 70.

  The region Q1 is set to include the polygonal line q1, and the region Q2 is set to include the straight line q2. The boundary between the region Q1 and the region Q2 is set between the polygonal line q1 and the straight line q2. In FIG. 7, the boundary between the region Q1 and the region Q2 is indicated by a broken line. The broken line q1 is an example of the relationship between the measured value of the stroke sensor 25 and the measured value of the control pressure sensor 73 when there is no liquid leakage in the front system and the shift to the hydro booster mode occurs due to some other abnormality. In the hydro booster mode, since the separation valve 60 is closed, liquid leakage in the rear system does not affect the measured value of the control pressure sensor 73. The straight line q2 is an example of the relationship between the measured value of the stroke sensor 25 and the measured value of the control pressure sensor 73 when liquid leakage occurs in the front system. When liquid leakage occurs in the front system, as shown in the figure, the measured value of the control pressure sensor 73, that is, the master cylinder pressure hardly increases even if the stroke increases.

  Therefore, the brake ECU 70 determines that liquid leakage has occurred in the front system when the measured stroke and master cylinder pressure are included in the region Q2. In addition, when the measured stroke and master cylinder pressure are included in the region Q1, the brake ECU 70 determines that an abnormality other than liquid leakage from the front system has occurred.

  Further, in this case, the abnormality of the control pressure sensor 73 and the liquid leakage from the front system can be determined by using the relationship between the stroke and the regulator pressure shown in FIG. This is because if there is no liquid leakage in the front system, not only the master cylinder pressure but also the regulator pressure increases rapidly in conjunction with the increase in stroke. On the other hand, when liquid leakage occurs in the front system, as indicated by the broken line n2 in FIG. 5, the regulator pressure does not increase so much when the stroke is small. Therefore, it is possible to distinguish between leakage from the front system and abnormality of the control pressure sensor 73 by determining whether or not there is an increase in the regulator pressure when the initial stroke is relatively small.

  The operation of the above configuration will be described below. First, when the brake control system is normal, regenerative cooperative control is normally executed. When the driver performs a brake operation, the regenerative braking force is preferentially used, and the hydraulic braking force generated by the hydraulic brake unit 20 compensates for the shortage of the driver's required braking force by the regenerative braking force alone. At this time, in the hydraulic brake unit 20, each wheel cylinder pressure is normally controlled by a common pressure-increasing linear control valve 66 and pressure-decreasing linear control valve 67.

  When the control hydraulic pressure deviates beyond the reference from the target hydraulic pressure determined in accordance with the driver's required braking force, the hydraulic brake unit 20 shifts to, for example, the hydro booster mode assuming that an abnormality has occurred. The hydraulic brake unit 20 identifies the location where the abnormality has occurred as described above. For example, it is determined whether the liquid leaks from the front system, the liquid leaks from the rear system, or any other abnormality. It is also determined whether there is an abnormality in the sensor.

  The hydraulic brake unit 20 executes regenerative assist control when it is determined that the liquid leaks from the front system, for example. That is, the hydraulic braking force is first used to cover the driver's required braking force, and the regenerative braking force is used in an auxiliary manner. In this embodiment, a regenerative braking force is applied to the front wheels that are drive wheels, and a hydraulic braking force is applied to the rear wheels that are driven wheels. In this case, the regeneration assist control continues even if the ABS control is executed on the rear wheel. This is because the influence of the sudden increase / decrease of the hydraulic pressure by the ABS control does not reach the front wheels. Sufficient braking force can be secured by continuing the regeneration assist control.

  Further, the required value of the regenerative braking force and the target deceleration that is the basis for calculating the required value are made to be as large as possible while interlocking with the driver's braking operation. For this purpose, for example, the hydraulic brake unit 20 calculates a regenerative braking force request value by selecting a sensor output value that gives a larger regenerative braking force request value. In addition, in order to obtain an appropriate regenerative braking force request value, a more reliable sensor is selected as a calculation basis, and the regenerative braking force request value is calculated. Thus, by obtaining a large regenerative braking force request value or target deceleration, it is possible to effectively utilize the regenerative braking force that can be generated and to secure the braking force at the time of abnormality. Further, since the braking force can be applied to the front wheels by the regeneration assist control, the balance of the braking forces of the front and rear wheels is also improved.

  6 electric motor, 7 hybrid ECU, 10 regenerative brake unit, 12 battery, 14 motor ECU, 20 hydraulic brake unit, 23 wheel cylinder, 27 master cylinder unit, 31 hydraulic booster, 32 master cylinder, 33 regulator, 34 reservoir, 60 separation valve, 64 master cut valve, 65 regulator cut valve, 66 pressure-increasing linear control valve, 67 pressure-decreasing linear control valve, 70 brake ECU, 71 regulator pressure sensor, 72 accumulator pressure sensor, 73 control pressure sensor.

Claims (2)

A brake control device that generates a braking force by using both a hydraulic braking force and a regenerative braking force,
Regenerative priority mode that preferentially uses the regenerative braking force and complements the hydraulic braking force to generate the required braking force, and supplementary regenerative braking force to the hydraulic braking force equivalent to the driver's brake operation A control unit that controls the braking force by selecting any of a plurality of control modes including the regeneration assist mode,
The control unit switches the control mode to the regeneration assist mode when an abnormality is detected in the regeneration priority mode,
The control unit stops the generation of the regenerative braking force when the ABS control is executed in the regeneration priority mode, and continues the generation of the regenerative braking force when the ABS control is executed in the regeneration assist mode. Control device.   The said control part performs the process for reducing the influence which the fluctuation | variation by the said ABS control of a hydraulic pressure measurement value has on the regenerative braking force request value in the said regeneration assistance mode. Brake control device.

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