JP2008222169A - Brake control device and brake control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correctly detect any fluid leakage from a pressure reducing valve when a specified operational mode is selected in a hydraulic brake device. <P>SOLUTION: A brake control device comprises a regulator for regulating the pressure of a working fluid to the working hydraulic pressure of a master cylinder with a power fluid pressure source for accumulating the working fluid by supplying the power being a high-pressure source, a working fluid supply path for supplying the working fluid to a plurality of wheel cylinders from the regulator, a pressure reducing valve arranged in a path for communicating the working fluid supply path with a reservoir, and a control device for detecting any fluid leakage from the pressure reducing valve based on the detected value of the working fluid pressure at a part communicated with the working fluid supply path while supplying the fluid pressure to the plurality of wheel cylinders from the regulator by closing the pressure reducing valve. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a brake control device and a brake control method for controlling a braking force provided to a wheel provided in a vehicle.

2. Description of the Related Art Conventionally, an electronically controlled brake device that can control a braking force by adjusting a hydraulic pressure applied to each wheel cylinder by a pressurization source and a hydraulic pressure control unit is known. For example, Patent Literature 1 describes a hydraulic brake device including a hydraulic booster, a master cylinder, a power hydraulic pressure source, and a plurality of brake cylinders. According to this hydraulic brake device, a plurality of brake cylinders, a hydraulic booster, a master cylinder, and a power hydraulic pressure source can be selectively communicated with each other with a simple circuit, and controllability can be improved. When the system is normal, hydraulic fluid is supplied from the power hydraulic pressure source to the brake cylinder. When an abnormality is detected, the control mode is switched to another control mode different from the normal mode. For example, the mode shifts to a mode in which a system for supplying hydraulic fluid from the master cylinder to the wheel cylinder and a system for supplying hydraulic fluid from the hydraulic booster to the remaining wheel cylinders are separated.
JP 2006-123889 A

  In the hydraulic brake device as in Patent Document 1, instead of providing a pressure increase control valve and a pressure reduction control valve for each vehicle wheel, the wheel cylinders of all wheels are connected by a set of pressure increase control valves and pressure reduction control valves. I have control. Thus, the cost is reduced by reducing the number of control valves installed. In a specific operation mode of the hydraulic brake device, the pressure increase control valve and the pressure reduction control valve are closed, and brake fluid is supplied from the regulator to all wheel cylinders to generate a braking force. Yes. Such an operation mode is set to perform control without using a linear control valve when the ABS is operated or the vehicle is stopped. In general, since the control valve has a movable part and the number of useful operations is determined, it is advantageous to select this mode to suppress the number of operations of the control valve.

  However, if the pressure reducing control valve breaks down and leakage occurs when the above operation mode is selected, brake fluid will flow out continuously from all wheel cylinders, making it impossible to generate the desired braking force. There is a fear.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a technique for accurately detecting liquid leakage from a pressure reducing valve when a specific operation mode is selected in a hydraulic brake device. It is in.

  One embodiment of the present invention is a brake control device. This device uses a power hydraulic pressure source that accumulates hydraulic fluid by supplying power as a high-pressure source, a regulator that regulates hydraulic fluid according to the hydraulic fluid pressure of the master cylinder, and supplies hydraulic fluid from the regulator to a plurality of wheel cylinders. A hydraulic fluid supply path, a pressure reducing valve disposed in a path communicating the hydraulic fluid supply path and the reservoir, and closing the pressure reducing valve to apply hydraulic pressure from the regulator to the plurality of wheel cylinders. A controller that detects liquid leakage from the pressure reducing valve based on a detected value of the hydraulic fluid pressure at a portion communicating with the hydraulic fluid supply path during the supply.

  In the regulator mode and the hydro booster mode, the hydraulic pressure is supplied from the hydraulic fluid supply path to the wheel cylinder. Therefore, if the hydraulic pressure leaks from the pressure reducing valve, the hydraulic fluid may flow out from all the wheel cylinders. According to this aspect, it is possible to detect a liquid leak from the pressure reducing valve and connect to a subsequent countermeasure.

  Another aspect of the present invention is also a brake control device. This device has a plurality of wheel cylinders that apply braking force to each of a plurality of wheels according to the hydraulic fluid pressure, and a hydraulic hydraulic pressure source that accumulates hydraulic fluid by supplying power as a high pressure source. A regulator for regulating the hydraulic fluid in accordance with the pressure, a reservoir for collecting the hydraulic fluid discharged from the plurality of wheel cylinders, and a hydraulic fluid supply for connecting the regulator and the plurality of wheel cylinders to supply the hydraulic fluid A regulator cut valve disposed in the hydraulic fluid supply path, a pressure reducing valve disposed in a path communicating with the hydraulic fluid supply path and the reservoir, and the operation on the regulator side from the regulator cut valve A regulator pressure sensor for detecting the hydraulic fluid pressure in the fluid supply path, and the hydraulic fluid supply on the wheel cylinder side from the regulator cut valve. A wheel cylinder pressure sensor that detects a hydraulic fluid pressure in a path, and a detected value of the regulator pressure sensor and a detected value of the wheel cylinder pressure sensor while supplying hydraulic fluid from the regulator to the plurality of wheel cylinders. And a controller that detects liquid leakage from the pressure reducing valve based on the result of comparing the above.

  Since the regulator cut valve is opened during the regulator mode, the hydraulic fluid pressure detected by the regulator pressure sensor upstream of the regulator cut valve and the wheel cylinder pressure sensor downstream are detected if normal. The hydraulic pressure is equal. In this embodiment, based on the result of the comparison of the hydraulic fluid pressure detected by these two sensors, liquid leakage from the pressure reducing valve communicating with the hydraulic fluid supply path can be detected, and this can be used as a countermeasure.

  When the hydraulic fluid pressure estimated based on the brake operation input does not match the hydraulic fluid pressure detected by the regulator pressure sensor, the control unit detects the detected value of the regulator pressure sensor and the detection of the wheel cylinder pressure sensor. When the detected values match, the liquid leakage from the pressure reducing valve may be determined.

  When the hydraulic fluid pressure based on the brake operation input and the hydraulic fluid pressure detected by the regulator pressure sensor do not match, the cause may be an abnormality of the regulator pressure sensor in addition to the liquid leakage from the pressure reducing valve. According to this aspect, by adding the process of comparing the detection values of the regulator pressure sensor and the wheel cylinder pressure sensor, it is possible to determine separately the leakage of the pressure reducing valve and the failure of the regulator pressure sensor.

  When it is determined that the brake pedal is held at a fixed position based on a brake operation input, the control unit performs control so that the regulator cut valve is opened after being temporarily closed, and the regulator pressure The detection value of the sensor and the detection value of the wheel cylinder pressure sensor are acquired, and when these detection values are not the same before and after the valve closing, it may be determined that liquid leakage has occurred from the pressure reducing valve.

  Since the hydraulic fluid does not flow from outside the regulator while the regulator mode is being executed, the brake pressure should be constant regardless of whether the regulator cut valve is opened or closed when the brake pedal is in a fixed position. According to this aspect, when the sensor detection values are not the same before and after the opening and closing of the regulator cut valve, it is determined that liquid leakage has occurred from the pressure reducing valve. This eliminates the need to estimate the hydraulic fluid pressure based on the brake operation input.

  The pressure reducing valve includes a common pressure reducing valve for simultaneously reducing the hydraulic fluid pressure of all wheel cylinders according to a brake operation input, and an individual pressure reducing valve for controlling communication between the wheel cylinder of each wheel and the reservoir. May be included. In this case, when it is determined that there is a liquid leak, the control unit may specify whether the liquid leak has occurred from the common pressure reducing valve or the individual pressure reducing valve.

  You may further provide the holding valve which is each arrange | positioned in the separate flow path connected to the wheel cylinder of each wheel from the said hydraulic fluid supply path | route, and controls supply of the hydraulic fluid to each wheel cylinder. When it is determined that there is a liquid leak, the control unit closes the holding valves one by one to check whether the liquid leakage has stopped, and an individual flow path with a holding valve that has stopped the liquid leakage It may be determined that liquid leakage has occurred from the individual pressure reducing valve communicating with the valve. The controller may determine that liquid leakage has occurred from the common pressure reducing valve when liquid leakage does not stop even when any of the holding valves is closed.

  According to this, not only is it possible to detect liquid leakage when hydraulic fluid is supplied from the hydraulic fluid supply path, but liquid leakage has occurred in either the common pressure reducing valve or the individual pressure reducing valve by opening and closing the holding valve in order. Can be specified. Therefore, it becomes possible to quickly investigate the cause at the time of failure and the subsequent repair.

  Yet another embodiment of the present invention is a brake control method. This method uses a power hydraulic pressure source that accumulates hydraulic fluid by supplying power as a high-pressure source, a regulator that regulates hydraulic fluid according to the hydraulic fluid pressure of the master cylinder, and supplies hydraulic fluid from the regulator to a plurality of wheel cylinders. And a pressure reducing valve disposed in a path that communicates the hydraulic fluid supply path and the reservoir, the method comprising: closing the pressure reducing valve; While the hydraulic pressure is being supplied from the regulator to the plurality of wheel cylinders, the liquid leakage from the pressure reducing valve is detected based on the detected value of the hydraulic fluid pressure at the portion communicating with the hydraulic fluid supply path.

  Yet another embodiment of the present invention is also a brake control method. This method uses a plurality of wheel cylinders that apply braking force to each of a plurality of wheels according to the hydraulic fluid pressure, and a hydraulic fluid pressure source that accumulates hydraulic fluid by supplying power as a high-pressure source. A regulator for regulating the hydraulic fluid in accordance with the pressure, a reservoir for collecting the hydraulic fluid discharged from the plurality of wheel cylinders, and a hydraulic fluid supply for connecting the regulator and the plurality of wheel cylinders to supply the hydraulic fluid A brake control device comprising: a path; a regulator cut valve disposed in the hydraulic fluid supply path; and a pressure reducing valve disposed in a path communicating the hydraulic fluid supply path and the reservoir. And supplying the hydraulic fluid from the regulator to the plurality of wheel cylinders, and the hydraulic fluid on the regulator side from the regulator cut valve The hydraulic fluid pressure in the supply passage is detected, the hydraulic fluid pressure in the hydraulic fluid supply channel is detected on the wheel cylinder side from the regulator cut valve, and the hydraulic fluid pressure on the regulator side and the hydraulic fluid pressure on the wheel cylinder side are detected. Comparison is made, and liquid leakage from the pressure reducing valve is detected based on the comparison result.

  According to the present invention, when a specific operation mode is selected in the hydraulic brake device, it is possible to accurately detect liquid leakage from the pressure reducing valve.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a system diagram showing a brake control device 20 according to an embodiment of the present invention. A brake control device 20 shown in the figure constitutes an electronically controlled brake system (ECB) for a vehicle, and controls braking force applied to four wheels provided on the vehicle. The brake control device 20 according to the present embodiment is mounted on, for example, a hybrid vehicle that includes an electric motor and an internal combustion engine as a travel drive source. In such a hybrid vehicle, each of regenerative braking that brakes the vehicle by regenerating kinetic energy of the vehicle into electric energy and hydraulic braking by the brake control device 20 can be used for braking the vehicle. The vehicle in the present embodiment can execute brake regenerative cooperative control that generates a desired braking force by using both the regenerative braking and the hydraulic braking together.

  As shown in FIG. 1, the brake control device 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 pressure, Actuator 40.

  Disc brake units 21FR, 21FL, 21RR and 21RL apply braking force to the right front wheel, left front wheel, right rear wheel and 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 amount of operation 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 brake control device 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.

  Further, 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 flow paths 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 controlled to be turned on and off, and the closed state is guaranteed by the electromagnetic force generated by the solenoid when supplied with a prescribed control current, so that the solenoid is turned off. 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. If the pressure-increasing linear control valve 66 and the like are made common to each wheel cylinder 23 in this way, 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 brake control device 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 a host hybrid ECU (not shown) and the like, and based on control signals from the hybrid ECU and signals from various sensors, the pump 36 of the power hydraulic pressure source 30 and the hydraulic pressure The electromagnetic control valves 51 to 54, 56 to 59, 60, and 64 to 68 constituting the actuator 40 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 by a predetermined amount.

  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 sensors connected to the brake ECU 70 include stroke sensors 25 and 26 provided on the brake pedal 24. In this embodiment, two stroke sensors are provided for backup. The stroke sensors 25 and 26 detect a pedal stroke as an operation amount of the brake pedal 24 and give a signal indicating the detected value to the brake ECU 70. The output values of the stroke sensors 25 and 26 are also sequentially given to the brake ECU 70 at predetermined time intervals, and are stored and held by a predetermined amount in a predetermined storage area of the brake ECU 70.

  The brake control device 20 configured as described above can execute brake regeneration cooperative control. The brake control device 20 starts braking in response to 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 to be generated by the brake control device 20 by subtracting the braking force due to regeneration from the required braking force. Here, the braking force by regeneration is supplied to the brake control device 20 from the hybrid ECU. 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 based on the feedback control law so that the wheel cylinder pressure becomes the target hydraulic pressure.

  As a result, in the brake control device 20, the brake fluid is supplied from the power hydraulic pressure source 30 to the wheel cylinders 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.

  At this time, the brake ECU 70 closes the regulator cut valve 65 so that the brake fluid sent 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 control device 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. . 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.

  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 brake control device 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 for supplying the brake fluid from the regulator 33 to each wheel cylinder 23 is referred to as a regulator mode (REG 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.

  As described above, 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.

  During the control in the linear control mode, the wheel cylinder pressure may deviate from the target hydraulic pressure due to 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 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, since 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, the master system and the regulator system may be hereinafter referred to as a front system and a rear system, respectively. . 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. The right and left wheels are connected to different systems, 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. A pipe-type brake control device may be used.

  By the way, as described above, at the time of control in the regulator mode, the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 are closed, and the regulator 33 is connected to the four-wheel wheel cylinder via the regulator cut valve 65. Brake fluid is supplied to generate braking force. In this case, if the pressure-reducing linear control valve 67 breaks down and liquid leaks, the brake fluid will flow out continuously from all four wheel cylinders, and it may not be possible to generate a desired braking force.

  Therefore, in the present embodiment, there is provided a liquid leakage detection technique capable of distinguishing between liquid leakage from the pressure-reducing linear control valve and failure of other components when the regulator mode is selected.

  FIG. 2 is a flowchart of the liquid leakage detection process according to the first embodiment. The processing shown in FIG. 2 is executed at a constant cycle by the brake ECU 70 during control in the regulator mode.

  First, the brake ECU 70 acquires the stroke STK1 detected by the first stroke sensor 25 and the detected value Preg of the regulator pressure sensor 71, and compares the brake pressure estimated from the stroke STK1 with Preg (S12). When the regulator mode is executed, the regulator pressure pressurized according to the operation of the brake pedal by the driver is supplied to the wheel cylinder. Therefore, the brake pressure estimated from the stroke STK1 and the detection value Preg of the regulator pressure sensor coincide with each other. Should do. Therefore, the brake ECU 70 determines whether or not they match (S14). If they match (Y in S14), it can be determined that there is no brake fluid leakage from the portion communicating with the main flow path 45 and that it is normal (S20), and this flowchart is ended.

  When the brake pressure estimated from STK1 does not match Preg (N in S14), the brake ECU 70 first determines whether or not there is a failure of the stroke sensor. The brake ECU 70 acquires the stroke STK1 detected by the first stroke sensor 25 and the stroke STK2 detected by the second stroke sensor, and determines whether they match (S16). If the two detected values do not match (N in S16), the brake ECU 70 determines that either the first stroke sensor 25 or the second stroke sensor 26 has failed (S18), and ends this flowchart.

  If the two detected values match in S16 (Y in S16), the brake ECU 70 determines whether or not the detected value Preg of the regulator pressure sensor 71 and the detected value Pfr of the control pressure sensor 73 match (S22). ). In the regulator mode, the regulator cut valve 65 and the separation valve 60 are open, and the regulator flow path 62 and the main flow path 45 communicate with each other, so that leakage may occur regardless of whether the various electromagnetic control valves are normal. The detection value Preg of the regulator pressure sensor 71 and the detection value Pfr of the control pressure sensor 73 should match. Therefore, if the two detection values do not match (N in S22), the brake ECU 70 determines that either the regulator pressure sensor 71 or the control pressure sensor 73 has failed (S26), and ends this flowchart. The determination in S22 is a step for confirming that the hydraulic pressure sensor is normal as a precondition for determining failure of various electromagnetic control valves.

  When the detected values of the regulator pressure sensor 71 and the control pressure sensor 73 match (Y in S22), the brake ECU 70 controls the liquid from the control valve that is closed during the regulator mode among the control valves communicating with the main flow path 45. It is determined that a leak has occurred (S24). Specifically, the brake ECU 70 determines that any one of the pressure-reducing linear control valve 67 and the ABS pressure-reducing valves 56 to 59 is leaking. Hereinafter, it is determined which of these control valves is leaking.

  Here, the brake ECU 70 does not have to consider liquid leakage from the pressure-increasing linear control valve 66 and the master cut valve 64. This is because when the pressure increasing linear control valve 66 is leaking, the main flow path 45 and the power hydraulic pressure source 30 communicate with each other. At this time, a higher pressure brake fluid is supplied to the wheel cylinder 23, and the braking force applied to each wheel is increased. Similarly, when the master cut valve 64 leaks, the main flow path 45 and the master cylinder 32 communicate with each other, so that the braking force applied to each wheel increases.

  On the other hand, when liquid leaks from the pressure-reducing linear control valve 67 or the ABS pressure-reducing valves 56 to 59, the brake fluid is circulated from the wheel cylinder 23 to the reservoir 34 via the reservoir channel 55, and the braking force is reduced. It becomes a state. Therefore, when liquid leakage from these control valves occurs, it is necessary to detect a failure as early as possible.

  Returning to FIG. 2, the brake ECU 70 first checks for leakage of the ABS pressure reducing valves 56 to 59. Therefore, the brake ECU 70 sequentially closes the ABS holding valves 51, 52, 53, 54 on the path communicating with the wheel cylinders 23FR, 23FL, 23RR, 23RL of each wheel one by one (S28). Then, it is confirmed whether or not the decrease in the brake pressure detected by the regulator pressure sensor 71 or the control pressure sensor 73 has stopped when any of the ABS holding valves is closed (S30). As an example, by observing whether the brake pressure estimated from the stroke STK1 of the stroke sensor 25 and the detected value Preg of the regulator pressure sensor 71 coincide with each other, it is possible to confirm the stop of the decrease in brake pressure. Is possible.

  When the decrease of the brake pressure is stopped (Y in S30), the brake ECU 70 determines that there is liquid leakage from the ABS pressure reducing valve disposed in the same flow path as the ABS holding valve closed at that time (S34). ). If the brake pressure continues to drop regardless of which ABS holding valve is closed (N in S30), it is determined that there is a liquid leak from the pressure-reducing linear control valve 67 (S32).

  As described above, according to the first embodiment, based on the comparison result between the detected value of the regulator pressure sensor and the detected value of the control pressure sensor, whether or not there is liquid leakage from the control valve when the regulator mode is performed. Can be determined. In addition, when it is determined that there is a liquid leak, it is possible to determine which of the pressure reducing linear control valve and the ABS pressure reducing valve causes the liquid leak by sequentially opening and closing the four-wheel ABS holding valve. Therefore, it is possible to promptly find a failure that can lead to a reduction in braking force, such as a liquid leak from the pressure reducing control valve, and to lead to a subsequent response such as warning to the driver or stop of the vehicle.

  In this embodiment, it is possible not only to detect liquid leakage when the regulator mode is implemented, but also to determine which control valve is the cause, so that the cause investigation at the time of failure and the subsequent repair can be executed quickly. Is possible.

  Furthermore, abnormalities in the regulator pressure sensor or the control pressure sensor can be detected in the same flow.

Embodiment 2. FIG.
In the first embodiment, the brake pressure is estimated from the stroke of the brake pedal detected by the stroke sensor, and the liquid leakage from the pressure reducing linear control valve or the ABS pressure reducing valve is detected based on the comparison with the detected value of the regulator pressure sensor. Said to do. In the second embodiment, a technique for detecting liquid leakage from the pressure-reducing linear control valve or the ABS pressure-reducing valve without estimating the brake pressure will be described.

  FIG. 3 is a graph for explaining liquid leakage detection according to the second embodiment. In FIG. 3, the horizontal axis represents elapsed time, and the vertical axis represents pedal stroke or brake pressure. Line 101 is a pedal stroke, and lines 102 to 104 are brake pressures detected by regulator pressure sensor 71 or control pressure sensor 73.

While performing regulator mode, the driver starts depressing the brake pedal at time t _0, the time t ₁ after a case is assumed to hold the pedal position (see line 101). In this situation, as long as the pedal position is maintained and the regulator pressure is constant, the detected value Preg of the regulator pressure sensor 71 and the detected value Pfr of the control pressure sensor 73 are equal and constant. Here, once it closes the regulator cut valve 65 at time t _2, the again and was opened at time t _3. In the regulator mode, the master cut valve 64, the pressure increasing linear control valve 66, the pressure reducing linear control valve 67, and the ABS pressure reducing valves 56 to 59 are all closed. Therefore, when the regulator cut valve 65 is closed, the main flow path 45 and The communicating flow path is in a closed environment. Therefore, if the various control valves are normal, the detected value Preg of the regulator pressure sensor 71 and the detected value Pfr of the control pressure sensor 73 do not change even if the regulator cut valve is opened and closed while the pedal is held, and the line in FIG. 102.

On the other hand, when liquid leakage occurs from the pressure-reducing linear control valve 67 or the ABS pressure-reducing valves 56 to 59, the following occurs. When closing the regulator cut valve 65 at time t _2, the while the detection value Pfr of the control pressure sensor 73 in communication with the liquid leakage portion is lowered as shown by line 103, the regulator pressure is isolated from the liquid leakage portion The detection value Preg of the sensor 71 is constant. Therefore, a hydraulic pressure difference occurs between both sides of the regulator cut valve 65. When the regulator cut valve 65 is opened at time t ₃ , the detected value Preg of the regulator pressure sensor 71 that is in communication with the liquid leakage portion decreases as shown by the line 104, while the detected value of the control pressure sensor 73. Pfr increases due to the brake fluid flowing in due to the hydraulic pressure difference of the regulator cut valve 65, and finally the brake pressure detected by both sensors becomes equal.

  In this way, by opening and closing the regulator cut valve 65 while holding the brake pedal during the implementation of the regulator mode, it is possible to determine the presence or absence of liquid leakage from the pressure reducing linear control valve or the ABS pressure reducing valve.

FIG. 4 is a flowchart of a liquid leakage detection process according to the second embodiment. The processing shown in FIG. 2 is executed at a constant cycle by the brake ECU 70 during control in the regulator mode.
First, the brake ECU 70 determines whether or not the brake pedal 24 is held at a certain position by the driver (S42). This can be determined from the detection value of the stroke sensor, and some variation is allowed. If the pedal is not held (N in S42), this flowchart is terminated. If the pedal is held (Y in S42), the brake ECU 70 controls the motor 36a that drives the pump 36 not to rotate (S44). This process is to prevent the regulator pressure from changing. Subsequently, the brake ECU 70 once closes the regulator cut valve 65 and opens the valve after a predetermined time has elapsed (S46). Then, it is determined whether or not the detected value Preg of the regulator pressure sensor 71 and the detected value Pfr of the control pressure sensor 73 are constant before and after the opening and closing of the regulator cut valve 65 (S48).

  If both detected values are constant (Y in S48), the brake ECU 70 determines that there is no leakage from the control valve and that it is normal (S52), and ends this flowchart. If both the detected values are not constant (N in S48), the brake ECU 70 determines that any one of the pressure-reducing linear control valve 67 and the ABS pressure-reducing valves 56 to 59 is leaking (S50).

  Subsequently, the brake ECU 70 first checks for leakage of the ABS pressure reducing valves 56 to 59. Therefore, the brake ECU 70 sequentially closes the ABS holding valves 51, 52, 53, 54 on the path communicating with the wheel cylinders 23FR, 23FL, 23RR, 23RL of each wheel one by one (S54). Then, it is confirmed whether or not the decrease in the brake pressure detected by the regulator pressure sensor 71 or the control pressure sensor 73 has stopped when any of the ABS holding valves is closed (S56).

  When the decrease in brake pressure is stopped (Y in S56), it is determined that there is liquid leakage from the ABS pressure reducing valve disposed in the same flow path as the ABS holding valve closed at that time (S60). If the brake pressure continues to decrease even when the ABS holding valve is closed (N in S56), it is determined that there is a liquid leak from the pressure-reducing linear control valve 67 (S58).

Embodiment 3 FIG.
In the first and second embodiments, it has been described that the presence or absence of liquid leakage from the pressure-reducing linear control valve during the regulator mode is determined. In the third embodiment, a technique for detecting a liquid leak from the pressure-reducing linear control valve when the hydro booster mode is performed will be described.

  As described above, in the hydro booster mode, 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. Further, the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 are also 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. In this way, in the hydro booster mode, even when the electromagnetic control valves are not energized due to an abnormality in the control system, the braking force is generated using the hydraulic booster. Therefore, in the hydro booster mode, if the pressure-reducing linear control valve 67 breaks down and liquid leaks, the brake fluid may flow out continuously from the wheel cylinder of the rear wheel, and the desired braking force may not be generated. is there.

  Therefore, in the third embodiment, when the hydro booster mode is selected, there is provided a liquid leakage detection technique that can distinguish between a liquid leakage from the pressure-reducing linear control valve and a failure of other parts.

  FIG. 5 is a flowchart of a liquid leakage detection process according to the third embodiment. The process shown in FIG. 5 is executed at a constant cycle by the brake ECU 70 during the control in the hydro booster mode.

  First, the brake ECU 70 acquires the stroke STK1 detected by the first stroke sensor 25 and the detected value Preg of the regulator pressure sensor 71, and compares the brake pressure estimated from the stroke STK1 with Preg (S72). When the hydro booster mode is executed, the regulator pressure pressurized according to the operation of the brake pedal by the driver is supplied to the wheel cylinder of the rear wheel. Therefore, the brake pressure estimated from the stroke STK1 and the detected value of the regulator pressure sensor It should match Preg. Therefore, the brake ECU 70 determines whether or not they match (S74). If they match (Y in S74), it can be determined that there is no brake fluid leakage from the portion communicating with the second flow path 45b and it is normal (S80), and this flowchart is ended.

  When the brake pressure estimated from STK1 and Preg do not match (N in S74), the brake ECU 70 first determines whether or not there is a failure of the stroke sensor. The brake ECU 70 acquires the stroke STK1 detected by the first stroke sensor 25 and the stroke STK2 detected by the second stroke sensor, and determines whether or not they match (S76). If the two detection values do not match (N in S76), the brake ECU 70 determines that either the first stroke sensor 25 or the second stroke sensor 26 has failed (S78), and ends this flowchart.

  If the two detected values match in S76 (Y in S76), the brake ECU 70 determines whether the detected value Preg of the regulator pressure sensor 71 and the detected value Pfr of the control pressure sensor 73 are in a relationship of Preg = k · Pfr. It is determined whether or not (S82). In the hydro booster mode, since the separation valve 60 is closed and the regulator flow path 62 and the master flow path 61 are not in communication, the detection value Preg of the regulator pressure sensor 71 and the detection value Pfr of the control pressure sensor 73 are The relationship should correspond to the servo ratio between the master cylinder 32 and the regulator 33. “K” is a coefficient corresponding to the servo ratio. If the above relationship is not satisfied (N in S82), the brake ECU 70 determines that either the regulator pressure sensor 71 or the control pressure sensor 73 has failed (S86), and ends this flowchart. The determination in S82 is a step for confirming that the hydraulic sensor is normal as a precondition for determining failure of various electromagnetic control valves.

  When the detected values of the regulator pressure sensor 71 and the control pressure sensor 73 satisfy the above relationship (Y in S82), the brake ECU 70 closes when the hydro booster mode is performed among the control valves communicating with the second flow path 45b. It is determined that liquid leakage has occurred from the control valve that is present (S84). Specifically, the brake ECU 70 determines that liquid leakage has occurred in either the pressure reducing linear control valve 67 or the rear wheel ABS pressure reducing valves 58 and 59. Hereinafter, it is determined which of these control valves is leaking.

  The brake ECU 70 first checks for liquid leakage from the ABS pressure reducing valves 58 and 59. Therefore, the brake ECU 70 closes the ABS holding valves 53 and 54 on the path communicating with the wheel cylinders 23RR and 23RL of each wheel one by one (S88). Then, it is confirmed whether or not the decrease of the brake pressure detected by the regulator pressure sensor 71 is stopped when any of the ABS holding valves is closed (S90). As an example, by observing whether the brake pressure estimated from the stroke STK1 of the stroke sensor 25 and the detected value Preg of the regulator pressure sensor 71 coincide with each other, it is possible to confirm the stop of the decrease in brake pressure. Is possible.

  When the decrease of the brake pressure is stopped (Y in S90), the brake ECU 70 determines that there is a liquid leak from the ABS pressure reducing valve disposed in the same flow path as the ABS holding valve closed at that time (S94). ). If the brake pressure continues to drop regardless of which ABS holding valve is closed (N in S90), it is determined that there is a liquid leak from the pressure-reducing linear control valve 67 (S92).

  As described above, according to the third embodiment, based on the comparison result between the detected value of the regulator pressure sensor and the detected value of the control pressure sensor, whether or not there is liquid leakage from the control valve when the hydro booster mode is performed. Can be determined. When it is determined that there is a liquid leak, the ABS holding valve on the second flow path 45b side is opened and closed in order to determine whether the liquid leak is occurring in the pressure reducing linear control valve or the ABS pressure reducing valve. be able to.

  If it is immediately after the ignition is turned on, instead of the process of S82, the brake ECU 70 opens the separation valve 60, and after the elapse of a predetermined time, the detected value Preg of the regulator pressure sensor 71 and the detected value Pfr of the control pressure sensor 73 It may be determined whether or not. If they do not match, the brake ECU 70 determines that either the regulator pressure sensor 71 or the control pressure sensor 73 has failed. If they coincide with each other, the brake ECU 70 determines that liquid leakage has occurred from the control valves that are closed when the hydrobooster mode is performed, among the control valves that communicate with the second flow path 45b. The above control is limited to immediately after the ignition is turned on. If the separation valve 60 is opened in a state where liquid leakage occurs, all the brake pressures of the four wheels will decrease. That's why.

  As described above, in the brake control device according to the present invention, a common pressure reducing linear control valve is provided from the viewpoint of cost reduction. If such a configuration is adopted, there is a risk that the brake fluid will flow out from all the wheel cylinders and the braking force will decrease when the pressure-reducing linear control valve fails, but according to the present invention, liquid leakage from the pressure-reducing linear control valve may occur. Can be reliably detected and used for subsequent measures.

  The present invention has been described based on some embodiments. These embodiments are merely examples, and modifications such as arbitrary combinations of the embodiments, each component of the embodiments, and any combination of the processing processes are also within the scope of the present invention. It will be understood by those skilled in the art.

  The present invention is not limited to the above-described embodiments, and various modifications such as design changes can be added based on the knowledge of those skilled in the art. The configuration shown in each drawing is for explaining an example, and can be appropriately changed as long as the configuration can achieve the same function.

  In the embodiment, the stroke sensor that detects the pedal stroke is used as the operation amount of the brake pedal. However, another brake operation amount detection means may be used. For example, a pedal depression force sensor that detects an operation force as the operation amount of the brake pedal may be used.

It is a distribution diagram showing a brake control device concerning one embodiment of the present invention. 3 is a flowchart of a liquid leakage detection process according to the first embodiment. 6 is a graph for explaining liquid leakage detection according to the second embodiment. 10 is a flowchart of a liquid leak detection process according to the second embodiment. 10 is a flowchart of a liquid leak detection process according to Embodiment 3.

Explanation of symbols

  20 brake control device, 23 wheel cylinder, 27 master cylinder unit, 31 hydraulic booster, 32 master cylinder, 33 regulator, 34 reservoir, 51-54 ABS holding valve, 56-59 ABS pressure reducing valve, 60 separation valve, 64 master cut Valve, 65 regulator cut valve, 66 pressure-increasing linear control valve, 67 pressure-reducing linear control valve, 70 brake ECU, 71 regulator pressure sensor, 72 accumulator pressure sensor, 73 control pressure sensor.

Claims (9)

A regulator that regulates hydraulic fluid according to the hydraulic fluid pressure of the master cylinder, using a hydraulic power source that accumulates hydraulic fluid by supplying power as a high-pressure source;
A hydraulic fluid supply path for supplying hydraulic fluid from the regulator to the plurality of wheel cylinders;
A pressure reducing valve disposed in a path communicating with the hydraulic fluid supply path and the reservoir;
While the pressure reducing valve is closed and the hydraulic pressure is supplied from the regulator to the plurality of wheel cylinders, the pressure reducing valve is operated based on the detected value of the hydraulic fluid pressure at the portion communicating with the hydraulic fluid supply path. A control unit for detecting liquid leakage of
A brake control device comprising: A plurality of wheel cylinders for applying a braking force to each of the plurality of wheels according to the hydraulic fluid pressure;
A regulator that regulates hydraulic fluid according to the hydraulic fluid pressure of the master cylinder, using a hydraulic power source that accumulates hydraulic fluid by supplying power as a high-pressure source; and
A reservoir for collecting hydraulic fluid discharged from the plurality of wheel cylinders;
A hydraulic fluid supply path for connecting the regulator and the plurality of wheel cylinders to supply hydraulic fluid;
A regulator cut valve disposed in the hydraulic fluid supply path;
A pressure reducing valve disposed in a path communicating with the hydraulic fluid supply path and the reservoir;
A regulator pressure sensor for detecting the hydraulic fluid pressure in the hydraulic fluid supply path on the regulator side from the regulator cut valve;
A wheel cylinder pressure sensor for detecting a hydraulic fluid pressure in the hydraulic fluid supply path on the wheel cylinder side from the regulator cut valve;
While supplying hydraulic fluid from the regulator to the plurality of wheel cylinders, liquid leakage from the pressure reducing valve is based on a result of comparison between the detected value of the regulator pressure sensor and the detected value of the wheel cylinder pressure sensor. A control unit for detecting
A brake control device comprising:   When the hydraulic fluid pressure estimated based on the brake operation input does not match the hydraulic fluid pressure detected by the regulator pressure sensor, the control unit detects the detected value of the regulator pressure sensor and the detection of the wheel cylinder pressure sensor. The brake control device according to claim 2, wherein when the detected values coincide with each other, it is determined that liquid leakage has occurred from the pressure reducing valve.   When it is determined that the brake pedal is held at a fixed position based on a brake operation input, the control unit performs control so that the regulator cut valve is opened after being temporarily closed, and the regulator pressure The detection value of the sensor and the detection value of the wheel cylinder pressure sensor are acquired, and when these detection values are not the same before and after valve closing, it is determined that liquid leakage has occurred from the pressure reducing valve. Item 3. The brake control device according to item 2. The pressure reducing valve includes a common pressure reducing valve for simultaneously reducing the hydraulic pressure of all the wheel cylinders according to a brake operation input, and an individual pressure reducing valve for controlling communication between the wheel cylinder of each wheel and the reservoir. Including
5. The brake control according to claim 3, wherein when it is determined that there is a liquid leak, the control unit specifies whether the common pressure reducing valve or the individual pressure reducing valve has a liquid leak. apparatus. A holding valve for controlling the supply of hydraulic fluid to each wheel cylinder, which is disposed in an individual flow path communicating with the wheel cylinder of each wheel from the hydraulic fluid supply path;
When it is determined that there is a liquid leak, the control unit closes the holding valves one by one to check whether the liquid leakage has stopped, and an individual flow path with a holding valve that has stopped the liquid leakage The brake control device according to claim 5, wherein it is determined that liquid leakage has occurred from the individual pressure reducing valve communicating with the brake.   The brake control device according to claim 6, wherein the control unit determines that a liquid leak has occurred from the common pressure reducing valve if the liquid leak does not stop even when any of the holding valves is closed. . A regulator that regulates hydraulic fluid according to the hydraulic fluid pressure of the master cylinder, using a hydraulic power source that accumulates hydraulic fluid by supplying power as a high-pressure source;
A hydraulic fluid supply path for supplying hydraulic fluid from the regulator to the plurality of wheel cylinders;
A method of controlling a brake control device comprising: a pressure reducing valve disposed in a path communicating with the hydraulic fluid supply path and the reservoir;
While the pressure reducing valve is closed and the hydraulic pressure is supplied from the regulator to the plurality of wheel cylinders, the pressure reducing valve is operated based on the detected value of the hydraulic fluid pressure at the portion communicating with the hydraulic fluid supply path. A brake control method characterized by detecting a liquid leak. A plurality of wheel cylinders for applying a braking force to each of the plurality of wheels according to the hydraulic fluid pressure;
A regulator that regulates hydraulic fluid according to the hydraulic fluid pressure of the master cylinder, using a hydraulic power source that accumulates hydraulic fluid by supplying power as a high-pressure source;
A reservoir for collecting hydraulic fluid discharged from the plurality of wheel cylinders;
A hydraulic fluid supply path for connecting the regulator and the plurality of wheel cylinders to supply hydraulic fluid;
A regulator cut valve disposed in the hydraulic fluid supply path;
A pressure reducing valve disposed in a path communicating with the hydraulic fluid supply path and the reservoir;
A method for controlling a brake control device comprising:
Supplying hydraulic fluid from the regulator to the plurality of wheel cylinders;
Detecting the hydraulic fluid pressure in the hydraulic fluid supply path on the regulator side from the regulator cut valve,
Detecting the hydraulic fluid pressure in the hydraulic fluid supply path on the wheel cylinder side from the regulator cut valve;
Compare the hydraulic fluid pressure on the regulator side with the hydraulic fluid pressure on the wheel cylinder side,
A brake control method, comprising: detecting a liquid leak from the pressure reducing valve based on a comparison result.

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