JP5062070B2 - BRAKE CONTROL DEVICE AND BRAKE CONTROL METHOD - Google Patents

Description

  The present invention relates to a brake control technique, and more particularly to a brake control technique for controlling a wheel cylinder pressure so as to approach a determined target wheel cylinder pressure.

2. Description of the Related Art Conventionally, in vehicles such as automobiles, a braking control technique for increasing a wheel cylinder pressure by supplying hydraulic fluid from an accumulator to a wheel cylinder by opening and closing a pressure increasing valve is known. As such a braking control technique, for example, both an accumulator flow path that is connected to a wheel cylinder and provided with a pressure-increasing linear control valve and a regulator flow path that is connected to the wheel cylinder and provided with a regulator cut valve are provided. Has been proposed (see, for example, Patent Document 1).
JP 2007-131247 A

  In the braking control device described in the above-mentioned patent document, the hydraulic fluid is usually supplied from the regulator cut flow path to the wheel cylinder to give a braking force to the wheel. On the other hand, for example, in an emergency, the driver may depress the brake pedal strongly. In such a case, it may be required to increase the wheel cylinder pressure more rapidly than in the case of using only the regulator cut flow path.

  The present invention has been made in view of these problems, and an object of the present invention is to provide a braking control technique capable of appropriately generating a braking force even when it is necessary to quickly increase the wheel cylinder pressure. There is to do.

In order to solve the above problem, the braking control apparatus according to one embodiment of the present invention is connected to a wheel cylinder, Ho Lee Rushirinda pressure is boosted by the hydraulic fluid to the wheel cylinder in accordance with depression of the brake pedal flows a first flow path that is connected to the wheel cylinder, first the hydraulic fluid to the wheel cylinders is detected and the second flow path e Lee Rushirinda pressure is boosted by flow, the hydraulic pressure of the first flow path The target wheel cylinder pressure is determined using the detected value of the hydraulic pressure sensor and the first hydraulic pressure sensor, and the flow of the hydraulic fluid to the wheel cylinder through the second flow path is controlled, thereby determining the determined target wheel Wheel cylinder pressure control means for controlling the wheel cylinder pressure so as to approach the cylinder pressure. When the hydraulic fluid is supplied to the wheel cylinder through the first flow path, the wheel cylinder pressure control means performs a compensation determination process for determining the target wheel cylinder pressure using a value compensated for the hydraulic pressure fluctuation in the first flow path. Execute.

  For example, the wheel cylinder pressure can be rapidly increased by supplying the hydraulic fluid to the wheel cylinder using not only the second flow path but also the first flow path. On the other hand, when hydraulic fluid is supplied to the wheel cylinder through the first flow path, there is a possibility that temporary hydraulic pressure fluctuations occur in the first flow path. According to this aspect, it is possible to determine the target wheel cylinder pressure while suppressing the influence of such fluid pressure fluctuations, and it is possible to realize highly accurate braking force control.

  The wheel cylinder pressure control means is provided so as to be able to control the supply stop and release of the supply of hydraulic fluid to the wheel cylinder through the first flow path, and has a sudden braking condition in which a sharp increase in the wheel cylinder pressure is requested. When it is determined that the condition is not satisfied, the supply of hydraulic fluid to the wheel cylinder through the first flow path is stopped, and when it is determined that the sudden braking condition is satisfied, the supply of hydraulic fluid to the wheel cylinder is stopped through the first flow path. May be canceled and compensation determination processing may be executed.

  According to this aspect, even when the hydraulic pressure in the first flow path is reduced by releasing the supply stop of the hydraulic fluid to the wheel cylinder, it is possible to suppress a reduction in the target wheel cylinder pressure due to that. . For this reason, the influence which it has on a driver | operator's brake feeling can be suppressed by controlling so that a hydraulic fluid may not fully flow to a wheel cylinder through a 2nd flow path.

  The wheel cylinder pressure control means detects a change in hydraulic pressure indicating that the brake pedal is suddenly depressed in the first flow path when the supply of hydraulic fluid to the wheel cylinder through the first flow path is stopped. In this case, it may be determined that the sudden braking condition is satisfied.

  When the brake pedal is suddenly depressed while the supply of the hydraulic fluid to the wheel cylinder through the first flow path is stopped, the first flow path rapidly increases in pressure. According to this aspect, it is possible to accurately determine whether or not the sudden braking condition is satisfied by using such a change in hydraulic pressure in the first flow path.

  The braking control device according to an aspect of the present invention may further include a second hydraulic pressure sensor that detects a hydraulic pressure of the main flow path where the first flow path and the second flow path merge. The wheel cylinder pressure control means may execute the compensation determination process when it is determined that the detection value of the second hydraulic pressure sensor is increasing.

  When the flow of the hydraulic fluid to the wheel cylinder through the first flow path is started, the first hydraulic pressure sensor may detect a decrease in the hydraulic pressure due to the flow of the hydraulic fluid. However, even when the hydraulic pressure in the first flow path is reduced as described above, there is a possibility that the hydraulic pressure in the main flow path is appropriately increased by the flow of the working fluid from the second flow path. Higher than the channel. According to this aspect, it is possible to execute the compensation determination process at an appropriate time to be executed by determining whether or not to execute the compensation determination process using the hydraulic pressure of the main channel. Become.

  The wheel cylinder pressure control means sequentially holds the detection value of the first hydraulic pressure sensor acquired every predetermined time, and uses the latest detection value of the first hydraulic pressure sensor when it is determined that the sudden braking condition is not satisfied. If the target wheel cylinder pressure is determined and it is determined that the sudden braking condition is satisfied, the target wheel cylinder pressure is obtained by using the maximum value among the detection values of the predetermined number of first hydraulic pressure sensors obtained continuously. Compensation determination processing for determining

  According to this aspect, when the hydraulic pressure of the first hydraulic pressure sensor may decrease, the target wheel cylinder pressure can be determined through the compensation determination process that suppresses the decrease. For this reason, it is possible to calculate the target wheel cylinder pressure with high accuracy by a simple configuration in which the maximum value among the detection values of the predetermined number of first hydraulic pressure sensors is acquired.

  The wheel cylinder pressure control means holds in advance and holds data indicating a predetermined number set based on a period of decrease in hydraulic pressure in the first flow path when supplying hydraulic fluid to the wheel cylinder through the first flow path. In addition, the maximum value among the detection values of the predetermined number of first hydraulic pressure sensors acquired continuously may be acquired using the data.

  According to this aspect, it is possible to determine the target wheel cylinder pressure by referring to the detection value of the first hydraulic pressure sensor by an appropriate number set based on the hydraulic pressure decrease period. For this reason, it is possible to realize an accurate compensation determination process while suppressing an increase in control load.

  The braking control device according to an aspect of the present invention may further include a stroke sensor that detects an operation amount of the brake pedal. The wheel cylinder pressure control means may execute compensation determination processing that avoids using the detection value of the first hydraulic pressure sensor and determines the target wheel cylinder pressure using the detection value of the stroke sensor.

  According to this aspect, it is possible to determine the target wheel cylinder pressure while avoiding the use of the detection value of the first hydraulic pressure sensor that may decrease the detection value. For this reason, the influence of the fluid pressure fluctuation of the first flow path in the determination of the target wheel cylinder pressure can be suppressed, and the target wheel cylinder pressure can be determined with high accuracy.

  The braking control device according to an aspect of the present invention further includes a hydraulic fluid supply unit that supplies hydraulic fluid to the wheel cylinder through the second flow path, and a third hydraulic pressure sensor that detects a hydraulic pressure of the hydraulic fluid supply unit. May be. The wheel cylinder pressure control means is provided to set a maximum deceleration and to determine a target wheel cylinder pressure that does not exceed the set maximum deceleration. When it is determined that the sudden braking condition is satisfied, the third cylinder pressure sensor detects The maximum deceleration may be set using the value.

  Such hydraulic fluid supply means may be maintained at a high hydraulic pressure in order to increase the wheel cylinder pressure. According to this aspect, in the setting of the maximum speed, it is possible to suppress the influence of the hydraulic pressure fluctuation in the first flow path due to supplying the hydraulic fluid to the wheel cylinder through the first flow path. For this reason, the target wheel cylinder pressure can be accurately determined based on an appropriate maximum speed.

  The braking control device according to an aspect of the present invention may further include a second hydraulic pressure sensor that detects a hydraulic pressure of the main flow path where the first flow path and the second flow path merge. The wheel cylinder pressure control means performs a first determination for determining whether or not an abnormality has occurred in the stroke sensor using the relationship between the detection value of the first hydraulic pressure sensor and the detection value of the stroke sensor. Using the relationship between the detection value of the second hydraulic pressure sensor and the detection value of the stroke sensor, a second determination is performed to determine whether or not an abnormality has occurred in the stroke sensor. In the first determination or the second determination, When it is determined that no abnormality has occurred in the stroke sensor, a compensation determination process is executed in which the detection value of the first hydraulic pressure sensor is avoided and the target wheel cylinder pressure is determined using the detection value of the stroke sensor. May be. According to this aspect, the abnormality of the stroke sensor can be detected appropriately, and when the abnormality occurs in the stroke sensor, the use of the detected value can be avoided and the target wheel cylinder pressure can be appropriately determined.

  The braking control device according to an aspect of the present invention further includes a hydraulic fluid supply unit that supplies hydraulic fluid to the wheel cylinder through the second flow path, and a third hydraulic pressure sensor that detects a hydraulic pressure of the hydraulic fluid supply unit. May be. The wheel cylinder pressure control means may execute compensation determination processing for avoiding the use of the detection value of the first hydraulic pressure sensor and determining the target wheel cylinder pressure using the detection value of the third hydraulic pressure sensor.

  According to this aspect, it is possible to determine the target wheel cylinder pressure while avoiding the use of the detection value of the first hydraulic pressure sensor that may decrease the detection value. For this reason, the influence of the fluid pressure fluctuation of the first flow path in the determination of the target wheel cylinder pressure can be suppressed, and the target wheel cylinder pressure can be determined with high accuracy.

  The wheel cylinder pressure control means may end the determination of the target wheel cylinder pressure by the compensation determination process when the supply of the hydraulic fluid to the wheel cylinder through the first flow path is stopped.

  When the supply of hydraulic fluid to the wheel cylinder through the first flow path is stopped, the influence on the target wheel cylinder pressure calculation caused by the hydraulic pressure fluctuation in the first flow path is reduced. According to this aspect, it is possible to more appropriately control the braking force by returning to the control of determining the target wheel cylinder pressure based on the hydraulic pressure in the first flow path at such time.

  The braking control device according to an aspect of the present invention may further include a stroke sensor that detects an operation amount of the brake pedal. The wheel cylinder pressure control means calculates the operation speed of the brake pedal using the detection value of the stroke sensor, and when the calculated operation speed of the brake pedal becomes slower than a predetermined speed threshold, the target wheel by the compensation determination process is calculated. The determination of the cylinder pressure may be terminated.

  If the operation speed of the brake pedal is slow, the flow of hydraulic fluid to the wheel cylinder through the first flow path is also reduced, so that the hydraulic pressure fluctuation in the first flow path may be reduced. According to this aspect, according to this aspect, the braking force can be more appropriately controlled by returning to the control that determines the target wheel cylinder pressure based on the hydraulic pressure in the first flow path at such time. It becomes possible.

  When the determination of the target wheel cylinder pressure by the compensation determination process is completed, the wheel cylinder pressure control means gradually determines the target wheel cylinder pressure so as to gradually approach the target wheel cylinder pressure determined when the compensation determination process is not executed. Variation processing may be executed.

  According to this aspect, it is possible to avoid the target wheel cylinder pressure from changing significantly by ending the determination of the target wheel cylinder pressure by the compensation determination process. For this reason, the influence which it has on the brake feeling given to the driver can be suppressed.

  The wheel cylinder pressure control means, when ending the determination of the target wheel cylinder pressure by the compensation determination process, calculates the first deceleration calculated by executing the compensation determination process and the second deceleration calculated without executing the compensation determination process. A value obtained by multiplying the difference by a predetermined positive number less than 1 may be determined as the target deceleration, and a gradual change process may be performed in which the target wheel cylinder pressure is determined based on the determined target deceleration. According to this aspect, the target wheel cylinder pressure can be appropriately gradually changed by simple control.

Another aspect of the present invention is a braking control method. This method includes a step of determining whether or not a sudden braking condition for assuming that a sharp increase in wheel cylinder pressure is required, and a brake connected to the wheel cylinder when it is determined that the sudden braking condition is satisfied. a step for releasing the stop of the supply of hydraulic fluid to the wheel cylinders through the first flow path e i Rushirinda pressure is boosted by the hydraulic fluid to the wheel cylinder in accordance with depression of the pedal is flowing, the first flow path When the hydraulic fluid is supplied to the wheel cylinder through a step of executing compensation determination processing for determining a target wheel cylinder pressure using a value compensated for hydraulic pressure fluctuation in the first flow path, and a wheel connected to the wheel cylinder action of the wheel cylinder ho Lee Rushirinda pressure through the second flow path which is boosted by the hydraulic fluid to the cylinder to flow Comprising by controlling the flow of the liquid, and controlling the wheel cylinder pressure as close to the determined target wheel cylinder pressure, the.

  According to this aspect, when it is determined that such a sudden braking condition is satisfied, it is possible to determine the target wheel cylinder pressure while suppressing the influence of the hydraulic pressure fluctuation in the first flow path. For this reason, highly accurate braking force control can be realized.

  According to the present invention, it is possible to provide a braking control technique capable of appropriately generating a braking force even when it is necessary to quickly increase the wheel cylinder pressure.

  Hereinafter, embodiments of the present invention (hereinafter referred to as “embodiments”) will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a system diagram showing a braking control device 20 according to the first embodiment. The braking 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 in the vehicle. The braking control device 20 according to the first 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 electrical energy and hydraulic braking by the braking control device 20 can be used for braking the vehicle. The vehicle in the first 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 braking 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, 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 first embodiment applies 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. And send it out. 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. Although the disc brake units 21FR to 21RL are used in the first embodiment, other braking force applying mechanisms including a wheel cylinder 23 such as a drum brake may be used.

  In the first 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 master cylinder 32 and the regulator 33 have a so-called idle stroke. The idle stroke is a stroke from when the brake operation is not performed until the brake pedal 24 is depressed and the connection between the master cylinder 32 and the regulator 33 and the reservoir 34 is cut off. During the idle stroke, the fluid pressure in the master cylinder 32 and the regulator 33 does not increase because the reservoir 34 is in communication. The master cylinder unit 27 of the first embodiment is configured such that when the brake pedal is depressed, the idle stroke of the regulator 33 is first reduced as the stroke increases, and then the idle stroke of the master cylinder 32 is reduced. That is, the connection with the reservoir 34 is cut off in the order of the regulator 33 and the master cylinder 32.

  Hereinafter, for the sake of convenience, the pedal stroke when the connection between the regulator 33 and the reservoir 34 is cut off is referred to as a first cut-off stroke, and the stroke when the connection between the master cylinder 32 and the reservoir 34 is cut off is referred to as a second cut-off stroke. Called. In the first embodiment, the second cutoff stroke is larger than the first cutoff stroke. When the pedal stroke is between the first cutoff stroke and the second cutoff stroke, the regulator 33 has a higher pressure than the master cylinder 32 and a differential pressure is generated between the two hydraulic fluid chambers. This is because the regulator 33 is disconnected from the reservoir 34 and the hydraulic fluid is pressurized according to the stroke, whereas the master cylinder 32 is connected to the reservoir 34 and the hydraulic pressure does not increase.

  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 pressure is maintained within a set range to be maintained by the pump 36 (this may be referred to as an allowable range in the present specification). Based on the measurement value of the accumulator pressure sensor 72, the brake ECU 70 turns on the pump 36 to increase the accumulator pressure when the accumulator pressure falls below the lower limit of the allowable range, and when the accumulator pressure exceeds the upper limit of the allowable range. The pressurization is finished by turning off the pump 36.

  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.

  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. In other words, in the first embodiment, the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67 are a pair of common controls for controlling the supply and discharge of the working fluid delivered from the power hydraulic pressure source 30 to each wheel cylinder 23. It is provided as a control valve. Thus, if the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 are made common to the wheel cylinders 23, it is preferable from the viewpoint of cost as compared to providing a linear control valve 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 braking 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 first 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.

  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.

  Further, a stop lamp switch is connected to the brake ECU 70. The stop lamp switch is turned on when the brake pedal 24 is depressed. As a result, the stop lamp is turned on. When the depression of the brake pedal 24 is released, the stop lamp switch is turned off and the stop lamp is turned off. A signal indicating the lighting state of the stop lamp switch is input from the stop lamp switch to the brake ECU 70 every predetermined time, and is stored and held in a predetermined storage area of the brake ECU 70.

  The braking control device 20 configured as described above can execute brake regeneration cooperative control. The braking control device 20 receives the braking request and starts braking. 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 braking control device 20 by subtracting the braking force due to regeneration from the required braking force. Here, the effective value of the braking force due to regeneration is supplied from the hybrid ECU to the braking control device 20. 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 each wheel cylinder 23 via the pressure-increasing linear control valve 66, and a 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 first 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. The braking control device 20 according to the first embodiment naturally controls 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. Can do.

  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.

  When the brake pedal 24 is depressed, the brake ECU 70 uses the detection results of the stroke sensor 25 and the control pressure sensor 73 to start calculating the target wheel cylinder pressure. The brake ECU 70 controls the hydraulic actuator 40 to increase or decrease the wheel cylinder pressure so as to realize the calculated target wheel cylinder pressure. Therefore, the brake ECU 70 functions as a wheel cylinder pressure control unit that controls the hydraulic actuator to increase or decrease the wheel cylinder pressure.

  FIG. 2 is a flowchart showing a detailed procedure of wheel cylinder pressure control processing in the braking control apparatus 20 according to the first embodiment. The processing in this flowchart starts when the ignition switch of the vehicle is turned on, and is repeatedly executed every predetermined time until the ignition switch is turned off.

  The brake ECU 70 uses the detection value of the stroke sensor 25 and the detection value of the regulator pressure sensor 71 to determine whether or not the driver is depressing the brake pedal 24 to brake the vehicle. It is determined whether there is a braking request for braking (S10). Such determination of the presence / absence of a braking request is well-known and will not be described. When it is determined that there is no braking request (N in S10), the processing in this flowchart is temporarily ended.

  For example, depending on the driving condition, the driver may depress the brake pedal 24 strongly, so-called sudden depression. When the brake pedal 24 is suddenly depressed, it is considered that the driver wants to quickly obtain the braking force. In such a case, it is necessary to increase the wheel cylinder pressure rapidly. For this reason, when the brake pedal 24 is suddenly depressed, the braking control apparatus 20 according to the first embodiment supplies a hydraulic fluid not only through the accumulator flow path 63 but also through the regulator flow path 62, thereby increasing the number of steep wheel cylinders. It is possible to execute a regulator assist that realizes the pressure.

  When it is determined that there is a braking request (Y in S10), the brake ECU 70 refers to the regulator assist flag to determine whether or not the regulator cut valve 65 is closed, so that this regulator assist has already been executed. It is determined whether or not (S12). When the regulator cut valve 65 is closed (Y in S12), that is, when the regulator assist has not been executed yet, the brake ECU 70 determines whether or not the brake pedal 24 is suddenly depressed by the driver. It is determined whether or not the condition is satisfied (S14). This sudden depression determination condition is used as a rapid braking condition for requesting a sharp increase in wheel cylinder pressure.

  Specifically, the brake ECU 70 measures time with a counter from when it is determined that there is a braking request. The brake ECU 70 determines that there is a braking request, and when the detected value of the accumulator pressure sensor 72 has reached a predetermined pressure threshold from the start of opening of the pressure-increasing linear control valve 66 until a predetermined time elapses. Then, it is determined that a change in hydraulic pressure indicating that the brake pedal 24 has been suddenly depressed in the regulator channel 62 has been detected, and in this case, it is determined that the sudden depression determination condition has been satisfied.

If it is determined that the sudden stepping determination condition is not satisfied (N in S14), the brake ECU 70 determines that the driver does not require a sharp pressure increase in the wheel cylinder, and maintains the closed state of the regulator cut valve 65. And avoid performing regulator assist. At this time, the brake ECU 70 executes normal determination processing for determining the target wheel cylinder pressure based on both the detected value of the brake pedal 24 and the detected value of the regulator pressure sensor 71 (S20). The brake ECU 70 opens the pressure-increasing linear control valve 66 based on the target wheel cylinder pressure determined by the normal determination process. Thus the accumulator flow passage 63 is communicated with the wheel cylinders 23, hydraulic fluid is boosted is ho Lee Rushirinda pressure by flowing into the wheel cylinders 23. Thus, the brake ECU 70 executes wheel cylinder pressure control for controlling the wheel cylinder pressure to approach the target wheel cylinder pressure (S26).

When it is determined that the sudden stepping determination condition is satisfied (Y in S14), it is determined that the driver has requested a sharp increase in pressure of the wheel cylinder, and the brake ECU 70 opens the regulator cut valve 65 and executes the regulator assist. Is started (S16), and the regulator assist flag is set to ON. Accordingly regulator channel 62 are communicated with the wheel cylinders 23, hydraulic fluid to the wheel cylinder 23 according to depression of the brake pedal 24 is boosted fluidity to ho Lee Rushirinda pressure. Therefore, when the regulator assist is executed, the hydraulic fluid is supplied to the wheel cylinder 23 through both the accumulator flow path 63 and the regulator flow path 62, so that it is possible to quickly increase the wheel cylinder pressure.

  If the brake pedal 24 continues to be depressed, the main flow path 45 rises without decreasing the hydraulic pressure immediately after the regulator cut valve 65 is opened unlike the regulator flow path 62. Therefore, when the regulator cut valve 65 is opened and the execution of the regulator assist is started, the brake ECU 70 determines whether or not the detected value of the control pressure sensor 73 is increasing (S18), and the brake pedal 24 is depressed. It is determined whether or not it continues.

  Here, the brake ECU 70 performs the regulator assist by opening the regulator cut valve 65 after the hydraulic pressure in the regulator passage 62 increases to some extent. For this reason, immediately after the regulator cut valve 65 is opened, the working fluid in the regulator flow path 62 suddenly flows into the wheel cylinder. For this reason, there is a possibility that the hydraulic pressure in the regulator flow path 62 may decrease despite the brake pedal 24 being depressed. Even in such a case, if the target wheel cylinder pressure is determined by the normal determination process of S20, the target wheel cylinder pressure lower than the value that should be originally determined from the operation of the brake pedal 24 is determined, which affects the driver's brake feeling. May cause effects.

  For this reason, when it is determined that the detected value of the control pressure sensor 73 is increasing (Y in S18), compensation determination processing for the target wheel cylinder pressure is executed (S22). Specifically, the brake ECU 70 determines the target wheel cylinder pressure using a value that compensates for the hydraulic pressure fluctuation in the regulator flow path 62 due to the flow of hydraulic fluid to the wheel cylinder 23 through the regulator flow path 62. Execute the process. Thereby, the fall of the target wheel cylinder pressure by the hydraulic pressure fall of the regulator flow path 62 can be suppressed. A detailed execution procedure of the compensation determination process will be described later. When the target wheel cylinder pressure is determined by the normal determination process, the brake ECU 70 sets the normal determination process flag to off and the compensation determination process flag to on.

  If the detected value of the control pressure sensor 73 does not increase immediately after the regulator cut valve 65 is opened (N in S18), the brake ECU 70 may not continue to depress the brake pedal 24. And the normal determination process of the target wheel cylinder pressure is executed (S20). The brake ECU 70 executes wheel cylinder pressure control for controlling the wheel cylinder pressure to approach the target wheel cylinder pressure determined by the compensation determination process (S26).

  When the regulator assist has already been performed and the regulator cut valve 65 is open (N in S12), the brake ECU 70 executes a target wheel cylinder pressure compensation necessity determination process (S24). The compensation necessity determination process will be described later. The brake ECU 70 executes wheel cylinder pressure control for controlling the wheel cylinder pressure to approach the target wheel cylinder pressure determined through the compensation necessity determination process (S26).

  FIG. 3 is a flowchart illustrating an execution procedure of the normal determination process of S20 in FIG. 2 of the first embodiment. The brake ECU 70 determines the target deceleration by using both the latest detected value of the regulator pressure sensor 71 and the detected value of the stroke sensor 25 (S40). Specifically, the brake ECU 70 calculates a target deceleration using only the detection value of the regulator pressure sensor 71. Further, the brake ECU 70 calculates a target deceleration using only the detection value of the stroke sensor 25. The brake ECU 70 uses the two calculated target decelerations to determine one integrated target deceleration. When the target deceleration is determined in this way, the brake ECU 70 determines the target wheel cylinder pressure based on the determined target deceleration (S42). Since the calculation method of the target deceleration and the target wheel cylinder pressure is well known, detailed description is omitted.

  FIG. 4 is a flowchart showing an execution procedure of the compensation determination process in S22 in FIG. 2 of the first embodiment. In the first embodiment, the brake ECU 70 sequentially stores the detection value of the regulator pressure sensor 71 acquired every predetermined time in a storage unit such as a RAM to construct a hydraulic pressure fluctuation history. Further, the inventors have researched and developed that the period during which the hydraulic pressure in the regulator flow path 62 is reduced by opening the regulator cut valve 65 is generally constant in the hardware configuration of the similar hydraulic actuator 40. It became clear by. For this reason, this construction is such that a value obtained by multiplying the detection interval of the detection values of the regulator pressure sensor 71 by the construction number N representing the number of the construction values constituting the history corresponds to the hydraulic pressure drop period of the regulator flow path 62. The number N is preset. In the ROM of the brake ECU 70, data indicating the number N of construction is stored in advance.

  The brake ECU 70 refers to this construction number N data, and acquires the maximum value among the latest N detection values of the regulator pressure sensor 71 acquired continuously (S60). Next, the brake ECU 70 determines a target deceleration using both the acquired maximum value and the detected value of the stroke sensor 25 (S62). Specifically, the brake ECU 70 determines the target deceleration by the same calculation method as in the normal determination process of S20 except that this maximum value is used instead of the detected value of the regulator pressure sensor 71. When the target deceleration is determined, the brake ECU 70 determines the target wheel cylinder pressure based on the determined target deceleration (S64).

  FIG. 5 is a diagram illustrating changes in various values used for braking control when the compensation determination process according to the first embodiment is executed. In FIG. 5, “A” indicates a detection value of the stroke sensor 25. “B” indicates a target deceleration calculated using only the detection value of the stroke sensor 25. “C” indicates a value when the maximum value is acquired from the latest N detected values of the regulator pressure sensor 71 to be used for calculation of the target deceleration. “D” indicates a target deceleration calculated using only the detection value of the regulator pressure sensor 71. “E” indicates a target deceleration calculated using both B and D. “F” indicates a detection value of the control pressure sensor 73. “G” indicates the opening degree of the pressure-increasing linear control valve 66. “H” indicates the opening degree of the regulator cut valve 65. In addition, the curve shown with a broken line in FIG. 5 has shown the case where the target deceleration was calculated by the normal determination process instead of the compensation determination process.

  As shown in FIG. 5, when the regulator cut valve 65 opens at the timing indicated by H, the detected value of the regulator pressure sensor 71 may temporarily decrease immediately after that. Thus, by acquiring the maximum value among the latest N detection values in the regulator pressure sensor 71, as shown in C, the detection value of the regulator pressure sensor 71 is compensated and the decrease in the value is suppressed. Therefore, the target deceleration value calculated using the value of C is also suppressed from decreasing as indicated by D. As a result, the target deceleration calculated using both B and D is also suppressed as compared with the case of the normal determination process, as indicated by E.

  As described above, as shown in G, even when the regulator cut valve 65 is opened and the detected value of the regulator pressure sensor 71 decreases, the target value is obtained using the value shown in C that compensates the detected value of the regulator pressure sensor 71. By determining the wheel cylinder pressure, the opening degree of the pressure-increasing linear control valve 66 is suppressed. Since the main channel 45 is pressurized by supplying hydraulic fluid from the regulator channel 62 immediately after the regulator cut valve 65 is opened, the value of F indicating the fluid pressure in the main channel 45 is the regulator. Unlike the hydraulic pressure of the flow path 62, it does not decrease.

  FIG. 6 is a flowchart showing an execution procedure of the compensation necessity determination process of S24 in FIG. 2 of the first embodiment. Even when the regulator cut valve 65 is opened and the regulator assist is executed, the target wheel cylinder pressure is determined by the normal determination process instead of the compensation determination process in a predetermined case as will be described later. The brake ECU 70 refers to the normal determination process flag to determine whether or not the process has shifted to the normal determination process (S80). When the transition to the normal determination process has been completed (Y in S80), the brake ECU 70 determines the target wheel cylinder pressure in the normal determination process (S20).

  If the process has not shifted to the normal determination process (N in S80), the brake ECU 70 refers to the compensation end process flag to determine whether the compensation end process for shifting from the compensation determination process to the normal determination process is in progress. (S82). When the compensation end process is being performed (Y in S82), the brake ECU 70 determines whether or not the end condition of the compensation end process is satisfied (S84). In the first embodiment, the compensation ends when the difference between the first deceleration calculated by executing the compensation determination process and the second deceleration calculated without executing the compensation determination process becomes smaller than a predetermined value. It is a process end condition. Of course, the termination condition of the compensation termination process is not limited to this.

  If it is determined that the end condition of the compensation end process is satisfied (Y in S84), the brake ECU 70 turns off the compensation end process flag to end the compensation end process, and simultaneously turns on the normal determination process flag to turn on the normal determination process. (S20). When it is determined that the completion condition for the compensation end process is not satisfied (N in S84), the brake ECU 70 determines the target wheel cylinder pressure through the compensation end process (S88).

  If neither the normal determination process nor the compensation end process is in progress (N in S82), it means that the compensation determination process is in progress. In this case, the brake ECU 70 calculates the operation speed of the brake pedal 24 using the detection value of the stroke sensor 25, and determines whether or not the calculated depression speed Vst of the brake pedal 24 is smaller than the speed threshold value Vth. Then, it is determined whether or not the depression of the brake pedal 24 is continued (S86). If the stepping speed Vst is smaller than the speed threshold value Vth (Y in S86), the brake ECU 70 may not continue to step on the brake pedal 24, so the brake ECU 70 completes the compensation end process for ending the compensation determination process. Is executed (S88).

  In the first embodiment, during the compensation end process, the brake ECU 70 executes a gradual change process that determines the target wheel cylinder pressure so as to gradually approach the target wheel cylinder pressure that is determined when the compensation determination process is not executed. . This is to suppress sudden fluctuations in the target wheel cylinder pressure due to sudden termination of the compensation determination process. Specifically, when the brake ECU 70 finishes determining the target wheel cylinder pressure by the compensation determination process, the brake ECU 70 multiplies the difference between the first deceleration and the second deceleration described above by a predetermined positive number less than 1. To the target deceleration. The brake ECU 70 determines the target wheel cylinder pressure based on the determined target deceleration. Needless to say, the compensation end processing is not limited to such processing.

  When it is determined that the stepping speed Vst is equal to or higher than the speed threshold Vth (N in S86), the brake ECU 70 determines whether or not a regulator assist end condition is satisfied (S90). In the first embodiment, the operating condition of ABS (Antilock Brake System) is used as the regulator assist end condition as it is. Of course, other conditions may be adopted as the regulator assist end condition.

  When the regulator assist end condition is satisfied (Y in S90), the brake ECU 70 closes the regulator cut valve 65 (S92), sets the regulator assist flag to OFF, and ends the execution of the regulator assist. When the execution of the regulator assist is ended, the brake ECU 70 starts calculating the target wheel cylinder pressure by the compensation end process (S88). At this time, the brake ECU 70 turns off the compensation determination process flag and sets the compensation end process flag on. When the regulator cut valve 65 is closed, the risk of a decrease in the hydraulic pressure in the regulator flow path 62 is reduced. Thus, appropriate braking force control can be realized by gradually shifting from the compensation determination process to the normal determination process in conjunction with the closing of the regulator cut valve 65. If the regulator assist end condition is not satisfied (N in S90), the brake ECU 70 continues to determine the target wheel cylinder pressure through the compensation determination process (S22).

(Second Embodiment)
FIG. 7 is a flowchart showing an execution procedure of the compensation determination process in S22 in FIG. 2 of the second embodiment. The configuration of the braking control apparatus according to the second embodiment is the same as that of the first embodiment, and the execution procedure of the braking control is the same as that of the first embodiment unless otherwise specified.

  In the compensation determination process, the brake ECU 70 first performs a first determination for determining whether or not there is an abnormality in the stroke sensor 25 from the relationship between the detection value of the stroke sensor 25 and the detection value of the regulator pressure sensor 71 (S120). As a result of the first determination, when it is determined that the stroke sensor 25 is abnormal (Y in S120), the brake ECU 70 now determines the stroke sensor 25 from the relationship between the detection value of the stroke sensor 25 and the detection value of the control pressure sensor 73. A second determination is made to determine whether or not there is an abnormality (S122). As described above, in the second embodiment, whether or not there is an abnormality in the stroke sensor 25 is determined with high accuracy by performing the zone determination based on the first determination and the second determination.

  When it is determined that there is an abnormality in the stroke sensor 25 in both the first determination and the second determination (Y in S122), the brake ECU 70 executes a fail process of the electronically controlled brake system (S124). In this fail process, the brake ECU 70 closes the pressure-increasing linear control valve 66 and opens the regulator cut valve 65. As a result, the wheel cylinder pressure can be directly increased through the regulator passage 62 by the depression operation of the brake pedal 24. Since such a fail process is known, a description thereof will be omitted. When the fail process is executed, the braking control by the pressure-increasing linear control valve 66 and the like is finished.

  When it is determined that there is no abnormality in the stroke sensor 25 in at least one of the first determination and the second determination (N in S120 and N in S122), the brake ECU 70 uses the detected value of the accumulator pressure sensor 72 to reduce the maximum. The speed is determined (S126). Specifically, in place of the detection value of the regulator pressure sensor 71, the target deceleration is performed by the same calculation method as in the normal determination process of S20 except that a value obtained by subtracting a predetermined value from the detection value of the accumulator pressure sensor 72 is used. Is calculated and determined as the maximum deceleration. Since the accumulator pressure is maintained at a constant high pressure by the pump 36, the influence of opening the regulator cut valve 65 is small. Therefore, an appropriate maximum deceleration can be set by using the detection value of the accumulator pressure sensor 72.

  When the maximum deceleration is determined in this way, the brake ECU 70 determines the target deceleration using the detection value of the stroke sensor 25 so as not to exceed the maximum deceleration (S128), and based on the determined target deceleration. A target wheel cylinder pressure is determined (S130). As described above, in the second embodiment, the brake ECU 70 executes the compensation determination process that determines the target wheel cylinder pressure by using only the detection value of the stroke sensor 25 while avoiding the use of the detection value of the regulator pressure sensor 71. To do. As a result, it is possible to determine the target wheel cylinder pressure while avoiding the use of the detected value of the regulator pressure sensor 71 that may decrease the detected value. In addition, by setting the maximum deceleration appropriately in this way and calculating the target deceleration so as not to exceed this, the influence on the determined value of the target wheel cylinder pressure when an abnormality has occurred in the stroke sensor 25 is obtained. Suppressed.

(Third embodiment)
FIG. 8 is a flowchart showing an execution procedure of the compensation determination process in S22 in FIG. 2 of the third embodiment. The configuration of the braking control apparatus according to the third embodiment is the same as that of the first embodiment, and the execution procedure of the braking control is the same as that of the first embodiment unless otherwise specified.

  In the third embodiment, the brake ECU 70 executes a compensation determination process for determining a target deceleration using a value obtained by subtracting a predetermined value from the detection value of the accumulator pressure sensor 72 (S160). The method for determining the target deceleration is not limited to such a method, and the target deceleration may be determined by another method using the detection value of the accumulator pressure sensor 72, for example. When the target deceleration is determined, the brake ECU 70 determines the target wheel cylinder pressure based on the target deceleration (S162). As described above, in the third embodiment, when the regulator assist is started, the target wheel cylinder pressure is determined using the detection value of the accumulator pressure sensor 72. As a result, it is possible to determine the target wheel cylinder pressure while avoiding the use of the detected value of the regulator pressure sensor 71 that may decrease the detected value.

  The present invention is not limited to the above-described embodiments, and an appropriate combination of the elements of each embodiment is also effective as an embodiment of the present invention. Various modifications such as design changes can be added to each embodiment based on the knowledge of those skilled in the art, and embodiments to which such modifications are added can also be included in the scope of the present invention.

It is a systematic diagram showing a braking control device concerning a 1st embodiment. It is a flowchart which shows the detailed procedure of the wheel cylinder pressure control process in the braking control apparatus which concerns on 1st Embodiment. It is a flowchart which shows the execution procedure of the normal determination process of S20 in FIG. 2 of 1st Embodiment. It is a flowchart which shows the execution procedure of the compensation determination process of S22 in FIG. 2 of 1st Embodiment. It is a figure which shows the change of the various values used for braking control at the time of performing the compensation determination process which concerns on 1st Embodiment. It is a flowchart which shows the execution procedure of the necessity determination process of compensation of S24 in FIG. 2 of 1st Embodiment. It is a flowchart which shows the execution procedure of the compensation determination process of S22 in FIG. 2 of 2nd Embodiment. It is a flowchart which shows the execution procedure of the compensation determination process of S22 in FIG. 2 of 3rd Embodiment.

Explanation of symbols

  20 brake control device, 23 wheel cylinder, 24 brake pedal, 25 stroke sensor, 45 main flow path, 62 regulator flow path, 63 accumulator flow path, 65 regulator cut valve, 66 pressure-increasing linear control valve, 70 brake ECU, 71 regulator pressure Sensor, 72 accumulator pressure sensor, 73 control pressure sensor.

Claims (14)

Is connected to the wheel cylinder, a first flow path e i Rushirinda pressure is boosted by the hydraulic fluid to the wheel cylinder in accordance with depression of the brake pedal flows,
Is connected to the wheel cylinder, a second flow path E Lee Rushirinda pressure is boosted by the hydraulic fluid to the wheel cylinder flows,
A first hydraulic pressure sensor for detecting a hydraulic pressure in the first flow path;
The target wheel cylinder pressure is determined using the detection value of the first hydraulic pressure sensor, and the supply of hydraulic fluid to the wheel cylinder through the second flow path is controlled, so that the determined target wheel cylinder pressure is obtained. Wheel cylinder pressure control means for controlling the wheel cylinder pressure to approach,
With
The wheel cylinder pressure control means compensates for determining a target wheel cylinder pressure using a value compensated for fluid pressure fluctuation in the first flow path when hydraulic fluid is supplied to the wheel cylinder through the first flow path. run the determination process,
The wheel cylinder pressure control means is provided so as to be capable of controlling the supply stop and release of supply of hydraulic fluid to the wheel cylinder through the first flow path, and is configured to request a sharp increase in wheel cylinder pressure. When it is determined that the sudden braking condition is not satisfied, the supply of the hydraulic fluid to the wheel cylinder through the first flow path is stopped, and when it is determined that the sudden braking condition is satisfied, the wheel cylinder is passed through the first flow path. A brake control device that cancels the supply of hydraulic fluid to the vehicle and executes the compensation determination process . The wheel cylinder pressure control means is a hydraulic pressure change indicating that a brake pedal is suddenly depressed in the first flow path when supply of hydraulic fluid to the wheel cylinder through the first flow path is stopped. If but is detected, the brake control apparatus according to claim 1, characterized in that it is determined that satisfies the sudden braking conditions. A second hydraulic pressure sensor for detecting the hydraulic pressure of the main flow path where the first flow path and the second flow path merge;
The wheel cylinder pressure control means performs the compensation determination process when the supply stop of hydraulic fluid to the wheel cylinder through the first flow path is canceled and an increase in the detection value of the second hydraulic pressure sensor is detected. brake control apparatus according to claim 1 or 2, characterized in that run. The wheel cylinder pressure control means sequentially holds the detection values of the first hydraulic pressure sensor acquired every predetermined time, and determines that the sudden braking condition is not satisfied, the latest detection value of the first hydraulic pressure sensor. Is used to determine the target wheel cylinder pressure, and when it is determined that the sudden braking condition is satisfied, the target value is determined using the maximum value among the detection values of the predetermined number of first hydraulic pressure sensors acquired continuously. The braking control apparatus according to any one of claims 1 to 3 , wherein a compensation determination process for determining a wheel cylinder pressure is executed. The wheel cylinder pressure control means holds in advance data indicating the predetermined number set based on a fluid pressure drop period in the first flow path when supplying hydraulic fluid to the wheel cylinder through the first flow path. The braking control according to claim 4 , wherein the maximum value among the detection values of the predetermined number of first hydraulic pressure sensors acquired continuously is acquired using the stored data. apparatus. A stroke sensor for detecting the operation amount of the brake pedal;
The wheel cylinder pressure control means executes compensation determination processing for avoiding use of a detection value of the first hydraulic pressure sensor and determining a target wheel cylinder pressure using the detection value of the stroke sensor. The braking control device according to any one of claims 1 to 3 . Hydraulic fluid supply means for supplying hydraulic fluid to the wheel cylinder through the second flow path;
A third hydraulic pressure sensor for detecting a hydraulic pressure of the hydraulic fluid supply means;
Further comprising
The wheel cylinder pressure control means is provided to set a maximum deceleration and to determine a target wheel cylinder pressure that does not exceed the set maximum deceleration. When it is determined that a sudden braking condition is satisfied, the third hydraulic pressure sensor The braking control device according to claim 6 , wherein the maximum deceleration is set by using the detected value of. A second hydraulic pressure sensor for detecting the hydraulic pressure of the main flow path where the first flow path and the second flow path merge;
The wheel cylinder pressure control means performs a first determination for determining whether or not an abnormality has occurred in the stroke sensor using a relationship between a detection value of the first hydraulic pressure sensor and a detection value of the stroke sensor. And performing a second determination for determining whether or not an abnormality has occurred in the stroke sensor using the relationship between the detection value of the second hydraulic pressure sensor and the detection value of the stroke sensor. Alternatively, when it is determined in the second determination that no abnormality has occurred in the stroke sensor, the use of the detection value of the first hydraulic pressure sensor is avoided and the target wheel cylinder pressure is determined using the detection value of the stroke sensor. The braking control device according to claim 6 or 7 , wherein compensation determination processing is executed. Hydraulic fluid supply means for supplying hydraulic fluid to the wheel cylinder through the second flow path;
A third hydraulic pressure sensor for detecting a hydraulic pressure of the hydraulic fluid supply means;
Further comprising
The wheel cylinder pressure control means avoids using the detection value of the first hydraulic pressure sensor and executes a compensation determination process for determining a target wheel cylinder pressure using the detection value of the third hydraulic pressure sensor. The braking control device according to any one of claims 1 to 3 , wherein The wheel cylinder pressure control means ends the determination of the target wheel cylinder pressure by the compensation determination process when the supply of hydraulic fluid to the wheel cylinder through the first flow path is stopped. Item 10. The braking control device according to any one of Items 1 to 9 . A stroke sensor for detecting the operation amount of the brake pedal;
The wheel cylinder pressure control means calculates an operation speed of a brake pedal using a detection value of the stroke sensor, and the compensation determination process when the calculated operation speed of the brake pedal becomes lower than a predetermined speed threshold value. The brake control device according to any one of claims 1 to 10 , wherein the determination of the target wheel cylinder pressure according to (1) is terminated. The wheel cylinder pressure control means determines the target wheel cylinder pressure so as to gradually approach the target wheel cylinder pressure determined when the compensation determination process is not executed when the determination of the target wheel cylinder pressure by the compensation determination process is finished. brake control apparatus according to claim 10 or 11, characterized in that the gradual change process to be executed. When the wheel cylinder pressure control means finishes determining the target wheel cylinder pressure by the compensation determination process, the first deceleration calculated by executing the compensation determination process and the second deceleration calculated without executing the compensation determination process A value obtained by multiplying the difference from the deceleration by a predetermined positive number less than 1 is determined as a target deceleration, and a gradual change process is performed to determine a target wheel cylinder pressure based on the determined target deceleration. The braking control device according to claim 12 . Determining whether or not a sudden braking condition for requesting a sharp increase in wheel cylinder pressure is satisfied;
When it is determined that sudden braking conditions are satisfied, the wheel cylinder hydraulic fluid to the wheel cylinder in accordance with depression of the brake pedal is connected to the wheel cylinder through the first flow path e i Rushirinda pressure is boosted by flowing Releasing the supply of hydraulic fluid to
When hydraulic fluid is supplied to the wheel cylinder through the first flow path, executing a compensation determination process for determining a target wheel cylinder pressure using a value compensated for fluid pressure fluctuation in the first flow path;
By working fluid to the wheel cylinders are connected to the wheel cylinder to control the flow of hydraulic fluid to the wheel cylinders e i Rushirinda pressure through the second flow path to be boosted by flow, it determined target wheel cylinder Controlling the wheel cylinder pressure to approach the pressure;
A braking control method comprising:

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