JP5092972B2 - Brake control device - Google Patents

Description

  The present invention relates to a brake control device, and more particularly to a brake control device capable of accurately detecting a failure of braking force.

  2. Description of the Related Art As a vehicle brake control device, a device that applies braking force to a wheel using a hydraulic pressure or air pressure of a brake fluid as a pressure source is widely adopted. In such a brake control device, when a brake fluid leak or an air leak occurs, a failure of the braking force in which the braking force is not applied to the wheel is caused. For this reason, in the conventional brake control device, the failure state of the braking force is detected, and the braking force applied to the non-failed wheel is controlled so that the vehicle is safely stopped.

For example, Patent Literature 1 discloses a brake control device that detects a wheel failure in which hydraulic pressure control based on anti-skid control is performed. In this brake control device, when the wheel speed of the anti-skid control target wheel should be lower than the wheel speed of the non-control target wheel, when the former is larger, the liquid based on the anti-skid control is applied to the wheel. It is determined that pressure control is not performed, and it is determined that the wheel is in a failed state. Thus, in the brake control system described in Patent Document 1, the failure of the braking force is detected by comparing the wheel speeds of the two wheels.
JP-A-8-282465

  However, there is a difference in the diameter of the tires mounted on each wheel, the distribution of braking force to each wheel, the load applied to each wheel during braking, and how well the brake is applied due to wear of the brake pads of each wheel. An unpredictable difference occurs in the wheel speed of each wheel. Therefore, when the wheel speeds of the two wheels are compared as in the above-described prior art, there is a problem that a failure of the braking force is erroneously detected.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a brake control device that can accurately detect a failure in braking force.

  In order to achieve this object, the brake control device according to claim 1 is provided with braking force applying means for applying a braking force to each of a plurality of wheels provided in the vehicle, and each wheel by the braking force applying means. By applying an inspection drive pattern and controlling the brake force applied to a predetermined failure inspection target wheel to decrease or maintain for a predetermined time within a period during which the braking force is applied to The braking force inspection means for inspecting the braking force of the failure inspection target wheel, the wheel speed detection means for detecting the wheel speed as the rotational speed of the failure inspection target wheel, and the braking force inspection means If no change on the acceleration side is observed in the wheel speed detected by the wheel speed detecting means while the braking force applied to the wheel to be inspected is inspected, braking And a malfunction detecting means for detecting that a failure state but not applied.

  In this specification, “no change on the acceleration side is observed” means that the wheel speed generated when the test drive pattern is given is the same as that when the test drive pattern is not given. It means to keep moving with the same inclination as when there is no. On the other hand, when the slope of the decrease in wheel speed becomes gentler, the wheel speed becomes constant, or the wheel speed increases, compared to the case where the same pattern is not given, It is referred to as “seen” or “changes to the acceleration side”.

  The brake control device according to claim 2 is the brake control device according to claim 1, wherein the braking force inspection unit increases the braking force applied to each wheel by the braking force application unit. The braking force of the failure inspection target wheel is inspected by giving and controlling the inspection drive pattern to the failure detection target wheel.

  According to a third aspect of the present invention, there is provided a brake control device comprising: braking force applying means for applying a braking force to each of a plurality of wheels having a front wheel and a rear wheel provided in a vehicle; and a braking force applied to the rear wheel. Before the increase of the braking force applied to the rear wheel by the rear wheel braking force suppression control means for suppressing the increase and the rear wheel braking force suppression control means, it is applied to each wheel by the braking force applying means. By providing and controlling an inspection drive pattern so as to decrease or maintain the braking force applied to at least one of the front wheels for a predetermined time within a period during which the braking force is increased, the front wheel Braking force inspection means for inspecting the braking force of the vehicle, wheel speed detection means for detecting the wheel speed, which is the rotational speed of the wheel, for the front wheel to which the braking force controlled by the braking force inspection means is applied, and the braking force Inspector When the wheel speed detected by the wheel speed detection means does not change on the acceleration side while the braking force applied to the front wheel is inspected, the loss that the braking force is not applied to the front wheel. A failure detection means for detecting that the vehicle is in a fallen state; and when the failure detection means detects that the front wheel is in a fallen state, it is applied to the rear wheel by the rear wheel braking force suppression control means. Rear wheel braking force suppression control prohibiting means for prohibiting suppression control of increase in braking force.

  According to a fourth aspect of the present invention, there is provided a brake control device comprising: braking force applying means for applying a braking force to each of a plurality of wheels having a front wheel and a rear wheel provided in a vehicle; and a braking force applied to the rear wheel. Applied to at least one of the front wheels while the rear wheel braking force suppression control means for suppressing the increase and the braking force applied to the rear wheel are suppressed and controlled by the rear wheel braking force suppression control means. By applying an inspection drive pattern to control the braking force to be reduced for a predetermined time, the braking force inspection means for inspecting the braking force of the front wheel, and the braking force controlled by the braking force inspection means are applied. The wheel speed detecting means for detecting the wheel speed, which is the rotational speed of the wheel, is detected by the wheel speed detecting means while the braking force applied to the front wheel is inspected by the braking force inspection means. The When no change in the acceleration side is observed in the wheel speed, a failure detection means for detecting that the braking force is not applied to the front wheel, and the front wheel has failed due to the failure detection means. And a rear wheel braking force suppression control ending unit for ending the suppression control of an increase in braking force applied to the rear wheel by the rear wheel braking force suppression control unit when it is detected that the vehicle is in a state.

  The brake control device according to claim 5 is the brake control device according to any one of claims 1 to 3, further comprising: deceleration calculation means for calculating vehicle deceleration from the wheel speed detected by the wheel speed detection means. The braking force inspection means reduces the braking force when the vehicle deceleration calculated by the deceleration calculating means is equal to or less than a first predetermined value, and maintains the braking force in other cases. To control.

  A brake control device according to a sixth aspect of the present invention is the brake control device according to any one of the first to third aspects, wherein a deceleration calculation means for calculating a vehicle deceleration from a wheel speed detected by the wheel speed detection means; And a deceleration change calculating means for calculating a temporal change amount of the vehicle deceleration from the vehicle deceleration calculated by the deceleration calculating means, wherein the braking force inspection means is controlled by the deceleration calculating means. When the calculated vehicle deceleration is not more than a first predetermined value and the temporal change amount of the vehicle deceleration calculated by the deceleration change calculating means is not more than a second predetermined value, the control is performed. Control is performed so as to decrease the power and maintain the braking force in other cases.

  A brake control device according to a seventh aspect is the brake control device according to any one of the first to fourth aspects, further comprising: deceleration calculation means for calculating a vehicle deceleration from a wheel speed detected by the wheel speed detection means. The braking force inspection means includes a time for reducing or maintaining the braking force when the vehicle deceleration calculated by the deceleration calculation means is equal to or less than a third predetermined value. It is longer than the time when it is larger than the predetermined value.

  A brake control device according to an eighth aspect of the present invention is the brake control device according to any one of the first to fourth aspects, wherein a deceleration calculation means for calculating a vehicle deceleration from a wheel speed detected by the wheel speed detection means; And a deceleration change calculating means for calculating a temporal change amount of the vehicle deceleration from the vehicle deceleration calculated by the deceleration calculating means, wherein the braking force inspection means is the deceleration change calculating means. When the braking force is reduced or maintained when the temporal change amount of the vehicle deceleration calculated by the above is less than or equal to a fourth predetermined value, the temporal change amount of the vehicle deceleration is a fourth predetermined value. Longer than that time if larger.

  According to the brake control device of the first aspect, when the braking force is applied to each wheel by the braking force applying unit, the braking force applied to the predetermined failure inspection target wheel by the braking force inspection unit. A test drive pattern is provided so that the time is decreased or maintained for a predetermined time. If the braking force is correctly applied to the failure inspection target wheel, the wheel speed of the wheel is actually reduced while reducing or maintaining the braking force applied to the failure inspection wheel by the braking force inspection means. It is pulled by the vehicle speed, which is the speed of the vehicle, and goes up. On the other hand, if the failure inspection target wheel is in a failure state where no braking force is applied, the wheel speed of the wheel is dragged to the vehicle speed, and the wheel speed continues to decrease with the vehicle speed regardless of the braking force. According to the brake control device of claim 1, the wheel speed detected by the wheel speed detecting means while the braking force applied to the failure inspection target wheel by the braking force inspection means is reduced or maintained. If no change on the acceleration side is observed, the failure detection means detects that the wheel to be inspected is in a failure state, so that it is possible to accurately detect the failure of the braking force. it can. In addition, since it is possible to detect the failure of the braking force from the fluctuation of the wheel speed subject to the failure inspection, the influence of the error in the wheel speed that occurs when the wheel speeds of the two wheels are compared as in the prior art described above. Can be eliminated. Therefore, there is an effect that the failure of the braking force can be detected with high accuracy.

  According to the brake control device of the second aspect, in addition to the effect produced by the brake control device of the first aspect, when the braking force applied to each wheel by the braking force applying means is increased. The inspection drive pattern is provided so that the braking force applied to the failure inspection target wheel by the braking force inspection means is reduced for a predetermined time or maintained for a predetermined time. Thus, when performing the failure detection, when the braking force applied to each wheel is increased, the braking force applied to the failure detection target wheel is reduced or maintained, If there is no failure in the failure detection target wheel, the wheel speed of the failure inspection target wheel is reliably changed to the acceleration side by reducing or maintaining the braking force. Therefore, there is an effect that the failure detection can be reliably performed. Further, since the inspection drive pattern is given when the braking force applied to each wheel is increased, the failure detection is performed if at least the braking force applied to the failure inspection target wheel is maintained. be able to. Thus, when the inspection driving pattern is given so as to maintain the braking force applied to the failure inspection target wheel, the inspection driving pattern is applied so as to reduce the braking force applied to the failure inspection target wheel. As compared with the above, it is possible to reduce the degree of reduction of the braking force in the failure inspection target wheel. Therefore, there is an effect that it is possible to suppress the uncomfortable feeling felt by the vehicle occupant by the inspection by the braking force inspection means.

  According to the brake control device of the third aspect, the inspection drive pattern is provided so that the braking force applied to at least one of the front wheels by the braking force inspection means is reduced or maintained for a predetermined time. If no change on the acceleration side is observed in the wheel speed detected by the wheel speed detecting means while reducing or maintaining the braking force applied to the front wheel by the braking force inspection means, the failure occurs. Since the detection means detects that the front wheel is in a failed state, the failure of the braking force of the front wheel can be accurately detected by the same action as the brake control device according to claim 1. effective. In addition, since an increase in the braking force applied to the rear wheel is suppressed by the rear wheel braking force suppression control means, it is possible to prevent the rear wheel from being locked first with a load movement during braking. . On the other hand, if it is detected by the failure detection means that the front wheel is in a failed state before the increase in the braking force applied to the rear wheel is suppressed by the rear wheel braking force suppression control means, the rear wheel braking force The suppression control prohibiting means prohibits the suppression control of the increase in the braking force applied to the rear wheel by the rear wheel braking force suppression control means. As a result, when the front wheels are in a failed state, the suppression control of the increase in braking force applied to the rear wheels is definitely prohibited, so the vehicle can be safely operated while increasing the braking force applied to the rear wheels. There is an effect that it can be stopped.

  According to the brake control device of the fourth aspect, while the increase in the braking force applied to the rear wheel is controlled to be suppressed by the rear wheel braking force suppression control means, it is applied to at least one of the front wheels. An inspection drive pattern is provided by the braking force inspection means so as to reduce the braking force for a predetermined time. If no change on the acceleration side is observed in the wheel speed detected by the wheel speed detection means while the braking force applied to the front wheel is reduced by the braking force inspection means, the failure detection means Since it is detected that the front wheel is in a failed state, the effect of the braking force of the front wheel can be detected with high accuracy by the same operation as the brake control device according to claim 1. Further, since the increase in the braking force applied to the rear wheel is suppressed by the rear wheel braking force suppression control means, it is possible to prevent the rear wheel from being locked first as the load moves during braking. When the increase of the braking force applied to the rear wheel is controlled to be suppressed by the braking force suppression control means, and the failure detection means detects that the front wheel is in the failed state, the rear wheel braking force suppression control is performed. The termination control ends the suppression control of the increase in the braking force applied to the rear wheel by the rear wheel braking force suppression control unit. Thereby, when the front wheels are in a failure state, there is an effect that the vehicle can be safely stopped while increasing the braking force applied to the rear wheels. Furthermore, after the increase in the braking force applied to the rear wheel is suppressed and controlled by the rear wheel braking force suppression control means, the application of the inspection drive pattern by the braking force inspection means and the failure detection by the failure detection means are performed. Therefore, when the condition for suppressing the increase in the braking force applied to the rear wheel is satisfied, the rear wheel by the rear wheel braking force suppression control means is not affected by the time taken to execute the failure detection. Suppression control of the braking force applied to can be executed immediately. Alternatively, in order to immediately execute the suppression control of the braking force applied to the rear wheel by the rear wheel braking force suppression control means, the detection of the failure is executed when the vehicle deceleration is not sufficiently large, Since it is not necessary to execute the fault detection in a short time, the accuracy of the fault detection can be ensured. Therefore, it is possible to suppress the increase in the braking force applied to the rear wheel and to prevent the rear wheel from being locked due to the execution of the failure detection while reliably performing the failure detection. effective.

  According to the brake control device of the fifth aspect, in addition to the effect produced by the brake control device according to any one of the first to third aspects, the vehicle reduction calculated by the deceleration calculation means by the braking force inspection means. When the speed is equal to or lower than the first predetermined value, the braking force of the wheel to be inspected is decreased, and in other cases, the braking force is maintained. Thereby, when the vehicle deceleration is small, if there is no failure, the wheel speed of the wheel to be inspected for failure is surely changed to the acceleration side due to the reduction of the braking force, so that the failure detection can be reliably performed. In this case, since the vehicle deceleration is small, the degree of reduction in braking force is small. Therefore, the uncomfortable feeling felt by the vehicle occupant by the inspection by the braking force inspection means can be suppressed. On the other hand, when the vehicle deceleration is large, if there is no failure, the wheel speed of the wheel to be inspected for failure is quickly increased. Therefore, the failure detection can be reliably performed only by maintaining the braking force without decreasing it. In this case, since the braking force is only maintained without being reduced, the degree of reduction in the braking force is small. Therefore, the uncomfortable feeling felt by the vehicle occupant by the inspection by the braking force inspection means can be suppressed. Therefore, there is an effect that the braking force failure can be detected safely and reliably while suppressing the uncomfortable feeling felt by the passenger of the vehicle.

  According to the brake control device of the sixth aspect, in addition to the effect produced by the brake control device according to any one of the first to third aspects, the vehicle reduction calculated by the deceleration calculation means by the braking force inspection means. When the speed is equal to or lower than the first predetermined value and the temporal change amount of the vehicle deceleration calculated by the deceleration change calculating means is equal to or lower than the second predetermined value, the control of the wheel subject to the failure inspection is performed. Power is reduced, otherwise the braking force is maintained. As a result, when the vehicle deceleration is small and the amount of change over time is small, if there is no failure, the wheel speed of the wheel subject to failure inspection is reliably changed to the acceleration side by reducing the braking force. Failure detection can be reliably performed. In this case, since the vehicle deceleration and the amount of change over time are small, the degree of reduction in braking force is small. Therefore, the uncomfortable feeling felt by the vehicle occupant by the inspection by the braking force inspection means can be suppressed. On the other hand, when the vehicle deceleration is large or the amount of change over time is large, the wheel speed of the wheel to be inspected for failure is quickly increased if there is no failure. Therefore, the failure detection can be reliably performed only by maintaining the braking force without reducing it. In this case, since the braking force is only maintained without being reduced, the degree of reduction in the braking force is small. Therefore, the uncomfortable feeling felt by the vehicle occupant by the inspection by the braking force inspection means can be suppressed. Therefore, there is an effect that the braking force failure can be detected safely and reliably while suppressing the uncomfortable feeling felt by the passenger of the vehicle.

  According to the brake control device of the seventh aspect, in addition to the effect produced by the brake control device according to any one of the first to fourth aspects, the vehicle reduction calculated by the deceleration calculation means by the braking force inspection means. The time for reducing or maintaining the braking force when the speed is equal to or lower than the third predetermined value is longer than that when the vehicle deceleration is higher than the third predetermined value. As a result, when the vehicle deceleration is small, the braking force is reduced or maintained for a long time, so that it is possible to reliably detect whether or not the wheel speed of the wheel subject to failure inspection has increased, thereby detecting failure detection. It can be done reliably. Even if the braking force is decreased or maintained for a longer time, the vehicle deceleration is small, so that the uncomfortable feeling felt by the vehicle occupant due to the inspection by the braking force inspection means can be suppressed. On the other hand, if the vehicle deceleration is large, the wheel speed of the wheel to be inspected for failure will quickly increase unless there is a failure. Therefore, even if the time for reducing or maintaining the braking force is shortened, The presence or absence of an increase in the wheel speed can be reliably detected. Therefore, failure detection can be performed reliably. In addition, since the time for reducing or maintaining the braking force is short, an increase in the braking distance due to a decrease in the braking force can be reduced, and the discomfort felt by the vehicle occupant can be suppressed by the inspection by the braking force inspection means. it can. Therefore, there is an effect that the braking force failure can be detected safely and reliably while suppressing the uncomfortable feeling felt by the passenger of the vehicle.

  According to the brake control device of the eighth aspect, in addition to the effect produced by the brake control device according to any one of the first to fourth aspects, the vehicle deceleration is calculated by the deceleration change calculating means, and the vehicle deceleration is reduced. The temporal change amount of the vehicle deceleration is calculated from the speed by the deceleration change calculation means. Then, when the time change amount of the vehicle deceleration by the braking force inspection means is equal to or less than the fourth predetermined value, the time change amount of the vehicle deceleration is the time for reducing or maintaining the braking force. 4 It becomes longer than the time when it is larger than the predetermined value. As a result, when the amount of temporal change in the vehicle deceleration is small, the braking force is reduced or maintained for a long time, so it is possible to reliably detect whether the wheel speed of the wheel subject to failure inspection has increased. Therefore, the failure detection can be surely performed. Even if the braking force is reduced or maintained for a long time, the temporal change amount of the wheel speed is small, so that the uncomfortable feeling felt by the vehicle occupant by the inspection by the braking force inspection means can be suppressed. On the other hand, if the amount of change in vehicle deceleration over time is large, the wheel speed of the wheel subject to failure inspection will increase rapidly if there is no failure, so even if the time for reducing or maintaining the braking force is shortened The presence or absence of an increase in the wheel speed of the wheel subject to failure inspection can be reliably captured. Therefore, failure detection can be performed reliably. In addition, since the time for reducing or maintaining the braking force is short, an increase in the braking distance due to a decrease in the braking force can be reduced, and the discomfort felt by the vehicle occupant can be suppressed by the inspection by the braking force inspection means. it can. Therefore, there is an effect that the braking force failure can be detected safely and reliably while suppressing the uncomfortable feeling felt by the passenger of the vehicle.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic diagram schematically showing the overall configuration of the brake control device 1 according to the first embodiment of the present invention.

  The brake control device 1 is mounted on a vehicle having four wheels (a right front wheel FR, a left front wheel FL, a right rear wheel RR, and a left rear wheel RL), and uses four brake fluid pressures as pressure sources. It is a device that applies braking force to FR to RL. The brake control device 1 can accurately detect a failure of the braking force in which the braking force is not applied to the wheel due to brake fluid leakage.

  As shown in FIG. 1, the brake control device 1 controls the hydraulic pressure generating device 11 that generates hydraulic pressure in the brake fluid and the hydraulic pressure supplied to the wheel cylinders 13 a to 13 d to increase, reduce, or hold the hydraulic pressure. And a wheel cylinder 13a that is attached to each of the wheels FR to RL, converts the hydraulic pressure supplied from the hydraulic control device 12 into a braking force, and applies the braking force to each of the wheels FR to RL. ˜13d and wheel speed sensors SE1 to SE4 that are respectively attached to the wheels FR to RL and detect wheel speeds that are the rotational speeds of the wheels, respectively, and an electronic control device that controls the hydraulic pressure control device 12 (hereinafter, “ ECU (Electronic Control Unit) ”) 14.

  The hydraulic pressure generator 11 includes a brake pedal 15, a booster 16, and a master cylinder 17. The brake pedal 15 is a pedal to which a pedaling force is applied by a passenger when a braking force is applied to the wheel. The brake pedal 15 is provided with a brake switch SW. The brake switch SW is turned on when a pedal force is applied to the brake pedal 15, and is turned off in other cases. The output signal of the brake switch SW is transmitted to the ECU 14.

  The booster 16 is a booster that amplifies the pedaling force applied to the brake pedal 15 and transmits it to the master cylinder 17.

  The master cylinder 17 is a device that generates hydraulic pressure in the brake fluid according to the pedaling force amplified by the booster 16, and is provided with two output ports 17a and 17b. A hydraulic pressure generated independently is output to each of the output ports 17a and 17b, a first hydraulic pressure circuit 18 described later is connected to one output port 17a, and a second hydraulic pressure is connected to the other output port 17b. A circuit 19 is connected. As a result, even if the brake fluid leaks from one hydraulic circuit and the braking force is lost, the other hydraulic circuit can apply the braking force to the wheel.

  The hydraulic pressure control device 12 includes a first hydraulic pressure circuit 18 and a second hydraulic pressure circuit 19 that are independent of each other, and is configured by so-called “front and rear piping”. That is, the first hydraulic circuit 18 includes a right front wheel path 18a connected to the wheel cylinder 13a mounted on the right front wheel FR and a left front wheel path 18b connected to the wheel cylinder 13b mounted on the left front wheel FL. The second hydraulic circuit 19 includes a right rear wheel path 19a connected to the wheel cylinder 13c mounted on the right rear wheel RR, and a wheel mounted on the left rear wheel RL. The rear wheel pipe includes a left rear wheel path 19b connected to the cylinder 13d.

  Reservoirs 29 and 30 for storing brake fluid are provided on the first hydraulic circuit 18 and the second hydraulic circuit 19, respectively. Each of the reservoirs 29 and 30 includes a piston and a spring. The reservoir 29 stores the brake fluid that has flowed out from the right front wheel path 18a and the left front wheel path 18b, and the reservoir 30 stores the right rear wheel path 19a. And the brake fluid which flowed out from the path | route 19b for left rear wheels is accommodated.

  The hydraulic pressure control device 12 is provided with pumps 31 and 32 and a motor M that drives the pumps 31 and 32 simultaneously on the hydraulic circuits 18 and 19. The suction sides of the pumps 31 and 32 are connected to the reservoirs 29 and 30, respectively, and the discharge sides are connected to the output ports 17a and 17b. The brake fluid stored in the reservoirs 29 and 30 is supplied to the master cylinder 17 based on driving of the pumps 31 and 32. The motor M drives the pumps 31 and 32 based on a control signal from the ECU 14.

  A first normally open solenoid valve 21 is provided between the output port 17a and the wheel cylinder 13a on the right front wheel path 18a, and a first normally closed solenoid valve 25 is provided between the wheel cylinder 13a and the reservoir 29. Is provided. Similarly, on the other paths 18b, 19a, 19b, second to fourth normally open solenoid valves 22-24 are provided between the output ports 17a, 17b connected to the paths and the wheel cylinders 13b-13d. The second to fourth normally closed solenoid valves 26 to 28 are provided between the wheel cylinders 13 b to 13 d and the reservoirs 29 and 30.

  The first to fourth normally open solenoid valves 21 to 24 are open when the electromagnetic coils provided in the respective solenoid valves are in a non-energized state, and are closed when the solenoid coil is in an energized state. It is a valve. The first to fourth normally closed solenoid valves 25 to 28 are solenoid valves that are closed when the respective electromagnetic coils are in a non-energized state and open when the respective electromagnetic coils are in an energized state. In addition, in FIG. 1, each solenoid valve 21-28 has shown the non-energized state.

  When the electromagnetic coils of the first normally open solenoid valve 21 and the first normally closed solenoid valve 25 are both in a non-energized state, the first normally open solenoid valve 21 is opened, and the first normally closed solenoid valve The valve 25 is closed. Therefore, the brake fluid supplied from the output port 17a flows into the wheel cylinder 13a via the right front wheel path 18a, and the hydraulic pressure in the wheel cylinder 13a is increased.

  On the other hand, when the electromagnetic coils of the first normally open solenoid valve 21 and the first normally closed solenoid valve 25 are both energized, the first normally open solenoid valve 21 is closed and the first normally closed solenoid valve is closed. The electromagnetic valve 25 is opened. Therefore, the brake fluid flows out from the wheel cylinder 13a to the reservoir 29 via the right front wheel path 18a, and the hydraulic pressure in the wheel cylinder 13a is reduced.

  When the electromagnetic coil of the first normally open solenoid valve 21 is energized and the electromagnetic coil of the first normally closed solenoid valve 25 is not energized, the first normally open solenoid valve 21 and the first Both the one normally closed solenoid valve 25 are closed. Therefore, the flow of the brake fluid through the right front wheel path 18a is restricted, and the hydraulic pressure in the wheel cylinder 13a is maintained.

  As for the second to fourth normally open solenoid valves 22 to 24 and the second to fourth normally closed solenoid valves 26 to 28 provided in the other paths 18b, 19a, and 19b, the energization and non-energization of the respective electromagnetic coils is performed. By controlling the state in the same manner as the first normally open solenoid valve 21 and the first normally closed solenoid valve 25, the hydraulic pressure in each of the wheel cylinders 13b to 13c is increased, reduced, and held. The energization and de-energization of the electromagnetic coils of the normally open solenoid valves 21 to 24 and the normally closed solenoid valves 25 to 28 are performed for each solenoid valve by a control signal from the ECU 14. Therefore, the supplied hydraulic pressure can be controlled for each of the wheel cylinders 13a to 13d.

  The wheel cylinders 13a to 13d are attached to the wheel cylinder 13a attached to the right front wheel FR, the wheel cylinder 13b attached to the left front wheel FL, the wheel cylinder 13c attached to the right rear wheel RR, and the left rear wheel RL. It is comprised by the wheel cylinder 13d made. Each wheel cylinder 13a-13d converts the hydraulic pressure output from the corresponding path 18a, 18b, 19a, 19b into a braking force, and applies a braking force according to the hydraulic pressure to each wheel FR-RL.

  The wheel speed sensors SE1 to SE4 include an FR wheel speed sensor SE1 attached to the right front wheel FR, an FL wheel speed sensor SE2 attached to the left front wheel FL, and an RR wheel speed sensor SE3 attached to the right rear wheel RR. The RL wheel speed sensor SE4 is mounted on the left rear wheel RL. The wheel speeds detected by the wheel speed sensors SE1 to SE4 are transmitted to the ECU 14.

  The ECU 14 transmits control signals to the electromagnetic valves 21 to 28 and the motor M of the hydraulic pressure control device 12 based on signals output from the brake switch SW and the wheel speed sensors SE1 to SE4, and controls each operation. It is a control device.

  Next, the detailed configuration of the ECU 14 will be described with reference to FIG. FIG. 2 is a block diagram showing an electrical configuration of the ECU 14. As shown in FIG. 2, the ECU 14 includes a CPU (Central Processing Unit) 41, a ROM (Read Only Memory) 42, a RAM (Random Access Memory) 43, a timing circuit 44, and an input / output port 45. The bus lines 46 are connected to each other. In addition, the input / output port 45 includes a wheel speed sensor SE (FR to RL wheel speed sensors SE1 to SE4), a brake switch SW, and first to fourth normally open valves provided in the hydraulic pressure control device 12 shown in FIG. The mold solenoid valves 21 to 24, the first to fourth normally closed solenoid valves 25 to 28, and the motor M are connected.

  The CPU 41 is configured according to programs and data stored in the ROM 42 and the RAM 43, and signals of the brake switch SW and the wheel speed sensor SE connected to the input / output port 45. Is an arithmetic device for controlling

  The ROM 42 is a non-rewritable memory that stores various programs executed by the CPU 41 and fixed values referred to when the programs are executed. In the ROM 42, a failure detection program 42a for causing the CPU 41 to execute the failure detection process shown in the flowchart of FIG. 5, and an electronic brake force distribution (EBD) process shown in the flowchart of FIG. A drive pattern map 42c and a drive time map 42d that are referred to when executing the EBD program 42b and the failure detection program 42a to be executed by the computer are stored.

  When the braking force applied to each wheel FR to RL by the wheel cylinders 13a to 13d is increasing, the failure detection program 42a is one failure inspection target wheel (hereinafter referred to as "target wheel"). The hydraulic pressure control device 12 is driven and controlled so that the hydraulic pressure applied to the wheel cylinder (hereinafter referred to as “W / C (Wheel Cylinder) pressure”) is reduced for a predetermined time or held for a predetermined time. This is a program for detecting the presence or absence of braking force failure in the target wheel from the change in the wheel speed of the target wheel.

  In this embodiment, the failure detection program 42a is executed by the CPU 41 before performing EBD control when an EBD control condition is satisfied in an EBD program 42b described later. Then, the CPU 41 sets a failure detection result of the target wheel in a failure detection result flag 43b described later, and ends this program. In the present embodiment, the right front wheel FR is set as the target wheel, and the failure detection of the front wheel FR controlled by the first hydraulic circuit 18 and the FL side system, that is, the front wheel piping is performed.

  The EBD program 42b is a program for executing EBD control. The EBD control is control that suppresses an increase in the W / C pressure of the wheel cylinders 13c and 13d of the right rear wheel RR and the left rear wheel RL when, for example, a predetermined slip occurs in the rear wheels RR and RL. . In addition, a value of a hydraulic pressure gauge (not shown) provided at the output port 17b of the master cylinder 17, that is, a master cylinder pressure (hereinafter referred to as “M / C (Master Cylinder) pressure”) is a predetermined hydraulic pressure. When the above occurs, or when a predetermined slip occurs in the rear wheels RR and RL and the M / C pressure exceeds a predetermined hydraulic pressure, the wheel cylinders 13c of the right rear wheel RR and the left rear wheel RL, Various EBD controls are known, such as suppressing an increase in 13d W / C pressure. By such EBD control, it is possible to prevent the rear wheels RR and RL from being locked before the front wheels FR and FL due to load movement during braking.

  The EBD program 42b is executed by the CPU 41 at predetermined time intervals (for example, 10 milliseconds), and first, whether the EBD control condition is satisfied (for example, whether a predetermined slip has occurred in the rear wheels RR and RL). Judging. When it is determined that the EBD control condition is satisfied, the failure detection program 42a is executed to detect the failure on the front wheels FR, FL side. When it is determined that there is no failure on the front wheels FR and FL, the EBD control is performed. When it is determined that there is a failure on the front wheels FR and FL, the EBD control is prohibited. Exit.

  Here, the failure detection principle of the failure detection program 42a will be described with reference to FIG. FIG. 3 is an explanatory diagram for explaining the failure detection principle of the failure detection program 42a when the target wheel is the right front wheel FR. FIG. 3 (a) shows the case where the right front wheel FR has not failed. (B) has shown the case where the right front wheel FR has failed.

  As shown in FIG. 3, this explanatory diagram includes the M / C pressure of the master cylinder 17, the front wheel W / C pressure which is the W / C pressure of the wheel cylinder 13a attached to the right front wheel FR, and the rear wheel RR. The rear wheel W / C pressure, which is the W / C pressure of the wheel cylinders 13c and 13d mounted on the RL, is shown as a graph with the vertical axis representing the hydraulic pressure and the horizontal axis representing the time. Further, the front wheel speed, which is the wheel speed of the right front wheel FR detected by the FR wheel speed sensor SE1, and the wheel speeds of the right rear wheel RR and the left rear wheel RL detected by the RR wheel speed sensor SE3 and the RL wheel speed sensor SE4. The rear wheel speed and the vehicle speed calculated from the value of the wheel speed sensor SE are shown in a gram with the vertical axis representing speed and the horizontal axis representing time. Further, the vehicle deceleration calculated from the vehicle speed and the vehicle deceleration change amount, which is a temporal change amount of the vehicle deceleration, are shown in a graph with the vertical axis and time as the horizontal axis, respectively. Further, “inspection drive” indicates a period in which drive control is performed on each of the electromagnetic valves 21 to 28 of the hydraulic pressure control device 12 in order to detect a failure of the target wheel.

  First, a case where the right front wheel FR has not failed will be described with reference to FIG. When a pedaling force is applied to the brake pedal 14, the master cylinder 17 generates an M / C pressure and increases the pressure. Here, if each solenoid valve 21-28 is in a non-energized state, the front wheel W / C pressure and the rear wheel W / C pressure are increased by the hydraulic pressure control means 12 in accordance with the M / C pressure. As a result, the front wheel speed and the rear wheel speed are decelerated by the respective W / C pressures, and the vehicle speed is also decelerated accordingly. Since the load moves toward the front wheel during braking, the rear wheel decelerates faster than the front wheel.

  Subsequently, during the increase of each W / C pressure, the first wheel W / C pressure is reduced for a predetermined time, that is, during the period in which “inspection driving” is active, or is maintained for that period. Both the open type solenoid valve 21 and the first normally closed type solenoid valve 25 are driven to be energized, or only the first normally open type solenoid valve 21 is drive controlled to be energized. As a result, the braking force applied to the right front wheel FR during this period is reduced or maintained. Therefore, the front wheel speed is pulled by the vehicle speed and goes up.

  Next, a case where the right front wheel FR has failed will be described with reference to FIG. When a depression force is applied to the brake pedal 14, an M / C pressure is generated and increased by the master cylinder 17 as in FIG. However, since the right front wheel FR has failed, even if the solenoid valves 21 to 28 are not energized, the hydraulic pressure is not transmitted to the front wheel W / C pressure, and only the rear wheel W / C pressure is M. The pressure is increased together with the / C pressure. In this state, the front wheel W / C pressure is reduced while the “inspection drive” is active, or the first normally open solenoid valve 21 and the first normally closed solenoid valve 25 are maintained during that period. Even if drive control is performed, the same occurs. As a result, the vehicle body speed is reduced as the rear wheel speed is reduced. The front wheel speed is dragged to the vehicle body speed and continues to decelerate with the vehicle body speed.

  Therefore, when the change in the front wheel speed is detected by the FR wheel speed sensor SE1 during the period in which the “inspection drive” is active, and a change on the acceleration side is seen in the front wheel speed, “no failure” If it is determined and no change on the acceleration side is observed in the front wheel speed, it can be determined that “there is a failure”.

  If it is determined that there is no failure in the right front wheel FR, it means that no liquid leakage has occurred in the first hydraulic circuit. Therefore, no failure has occurred in the left front wheel FL equipped with the wheel cylinder 13b connected to the first hydraulic circuit, and the braking force is applied to both the front wheels FR and FL. Therefore, as shown in FIG. 3A, the EBD control is performed to suppress the increase in the rear wheel W / C pressure and prevent the rear wheel from being locked first.

  On the other hand, if it is determined that “there is a failure” in the right front wheel FR, it means that a liquid leak has occurred in the first hydraulic circuit, and there is also a failure in the left front wheel FL. That is, no braking force is applied to the front wheels FR and FL. Therefore, as shown in FIG. 3B, the EBD control is not performed, and the rear wheel W / C pressure is increased together with the M / C pressure. Thereby, a vehicle can be stopped safely.

  In FIG. 3, the right front wheel FR has been described as the target wheel. However, even when the target wheel is the left front wheel FL, failure detection can be performed on the same principle, and whether or not EBD control can be performed can be determined. it can. Further, the failure detection can be performed based on the same principle even when the target wheel is the right rear wheel RR or the left rear wheel RL.

  Returning to FIG. The drive pattern map 42c and the drive time map 42d are respectively the W / Cs of the target wheels that are driven and controlled by the hydraulic pressure control device 12 when the CPU 41 executes the failure detection program 42a. It is a map for setting a driving pattern ("reduced pressure" or "holding") and driving time of pressure. Both the drive pattern map 42c and the drive time map 42d are based on the magnitudes of the second vehicle speed DV2 and the vehicle speed change amount (DV2-DV1) (see FIG. 5) calculated by the CPU 41, respectively. Set the time.

  Here, the drive pattern map 42c and the drive time map 42d will be described with reference to FIG. FIG. 4A is a schematic diagram schematically illustrating the contents of the drive pattern map 42c, and FIG. 4B is a schematic diagram schematically illustrating the contents of the drive time map 42d.

  In the drive pattern map 42c, as shown in FIG. 4A, when the second vehicle deceleration (DV2) is equal to or less than a first predetermined value, the vehicle deceleration change amount (DV2-DV1) is a second predetermined value. When the value is equal to or smaller than the value, the drive pattern is set to “depressurization”, and when the vehicle deceleration change amount (DV2−DV1) is larger than the second predetermined value, the drive pattern is set to “hold”. If the second vehicle deceleration (DV2) is greater than the first predetermined value, the drive pattern is set to “hold”.

  When the vehicle deceleration is small and the vehicle deceleration change amount is small, the difference between the vehicle speed and the front wheel speed is small, so the amount of increase in the front wheel speed is small. Therefore, in this case, by setting the drive pattern to “depressurized” by the drive pattern map 42c, the wheel speed can be reliably increased when the target wheel has not failed, and the failure detection is performed. It can be done reliably. In addition, since the degree of reduction in the braking force is small, it is possible to suppress the uncomfortable feeling felt by the vehicle occupant.

  On the other hand, when the vehicle deceleration is large or when the change in vehicle deceleration is large, the difference between the vehicle speed and the front wheel speed increases. Go up quickly. Therefore, even if the drive pattern is set to “hold” instead of “reduced pressure”, the wheel speed can be reliably increased. Further, in this case, since the degree of the braking force is small, it is possible to suppress the uncomfortable feeling felt by the vehicle occupant.

  In this way, by setting the drive pattern according to the magnitude of the vehicle deceleration and the amount of change in the vehicle deceleration based on the drive pattern map 42c, the control feeling is suppressed while suppressing the sense of discomfort felt by the vehicle occupant. Power failure detection can be performed safely and reliably.

  On the other hand, in the drive time map 42d, as shown in FIG. 4B, when the second vehicle deceleration (DV2) is equal to or less than the third predetermined value, the change amount (DV2-DV1) of the vehicle deceleration is the first. When it is 4 or less, the drive time is set to “T1”, and when the vehicle deceleration change amount (DV2−DV1) is greater than the fourth predetermined value, the drive time is set to “T2”.

  In addition, when the second vehicle deceleration (DV2) is larger than the third predetermined value and the vehicle deceleration change amount (DV2-DV1) is equal to or smaller than the fourth predetermined value, the driving time is set to “T3”. When the vehicle deceleration change amount (DV2-DV1) is greater than the fourth predetermined value, the drive time is set to “T4”.

  Here, the drive time map 42d defines that the drive time “T1” is longer than “T3” and “T2” is longer than “T4”. As described above, the drive time (“T1”, “T2”) with the smaller vehicle deceleration is set longer than the drive time (“T3”, “T4”) with the larger vehicle deceleration, thereby reducing the vehicle time. When the speed is small, the presence or absence of an increase in the wheel speed of the target wheel can be reliably captured. Therefore, failure detection can be performed reliably. Further, even if the driving time is lengthened, the vehicle deceleration is small, so that the uncomfortable feeling felt by the vehicle occupant can be suppressed. On the other hand, when the vehicle deceleration is large, even if the drive time is shortened, the presence or absence of an increase in the wheel speed of the wheel subject to failure inspection can be reliably detected, so that the failure detection can be reliably performed. . In addition, since the driving time is short, an increase in the braking distance due to a decrease in braking force can be reduced, and the uncomfortable feeling felt by the vehicle occupant can be suppressed.

  The drive time map 42d defines that the drive time “T1” is longer than “T2” and the drive time “T3” is longer than “T4”. Thus, the drive time (“T1”, “T3”) with the smaller amount of change in the vehicle deceleration is set to be longer than the drive time (“T2”, “T4”) with the greater amount of change in the vehicle deceleration. By increasing the driving time, the driving time with the smaller vehicle deceleration ("T1", "T2") is longer than the driving time with the larger vehicle deceleration ("T3", "T4"). It is possible to suppress the uncomfortable feeling felt by the vehicle occupant while reliably detecting the failure.

  In this way, by setting the drive time according to the magnitude of the vehicle deceleration and the amount of change in the vehicle deceleration based on the drive time map 42d, the control feeling is suppressed while suppressing the sense of discomfort felt by the passengers of the vehicle. Power failure detection can be performed safely and reliably.

  Returning to FIG. The RAM 43 is a rewritable and volatile memory for temporarily storing data necessary for the CPU 41 to execute various programs. The RAM 43 stores a failure detection end flag 43a and a failure detection result flag 43b.

  The failure detection end flag 43a is a flag indicating whether or not the failure detection by the failure detection program 42a has ended, and is set to “0” if it has not ended and “1” if it has ended. .

  This failure detection end flag 43a is referred to by the failure detection program 42a. When the failure detection end flag 43a is "0" when the failure detection program 42a is executed, the program detects the failure. In practice, this flag is set to "1". If the failure detection end flag 43a is “1”, the program ends without performing failure detection.

  The failure detection end flag 43a is referred to in the EBD program 42b. When the EBD control condition is satisfied and the failure detection end program 43a is executed, the failure detection end flag 43a is “1”. Then, it is determined that the failure detection process by the failure detection program 42a has been completed, and it is determined whether to execute EBD control according to the value of the failure detection result flag 43b.

  The failure detection end flag 43a is set to “0” as an initial value when an ignition switch (not shown) is turned on. The failure detection end flag 43a is also set to “0” even when the EBD control condition is not satisfied in the EBD program 42b.

  The failure detection result flag 43b is a flag for storing a result when failure detection is performed by the failure detection program 42a. When the result is “no failure”, “0” is set to “failure”. In the case of “present”, “1” is stored. The failure detection result flag 43b is set to “0” as an initial value when an ignition switch (not shown) is turned on. Thereafter, each time the failure detection is performed by the failure detection program 42a, the result is overwritten. The failure detection result flag 43b is referred to by the EBD program 42b, and it is determined from this failure detection result flag 43b whether or not to perform EBD control.

  The clock circuit 44 has an internal clock that records the current date and time, and is a known circuit that calculates the required time by comparing the date and time when the clock is started with the current date and time.

  Next, the failure detection process executed by the ECU 14 will be described with reference to FIG. FIG. 5 is a flowchart showing the failure detection process. This process is executed when the failure detection process is not executed when the EBD control condition is satisfied in the EBD process (see FIG. 6) described later.

  In this process, first, it is confirmed whether or not the failure detection end flag 43a is “0” (S101). If the failure detection end flag 43a is “1” (S101: No), the failure detection has already been detected. Since the process has been completed, the present process is terminated without detecting the failure. If the failure detection end flag 43a is “0” (S101: Yes), the process proceeds to S102.

  In S102, it is confirmed whether the system is normal. That is, it is confirmed whether each part connected to the input / output port 45 of the ECU 14 operates normally. Further, when the anti-skid control is performed by the hydraulic pressure control device 12, it is confirmed whether the anti-skid control can be normally performed. If the system is not normal (S102: No), the present process is terminated without detecting the failure. When the system is normal (S102: Yes), the process proceeds to S103.

  In S103, it is confirmed from the output signal of the brake switch SW whether the brake pedal is depressed. If it is not stepped on (S103: No), the failure detection cannot be performed correctly, and the present processing is terminated without performing the failure detection. Moreover, if it is stepped on (S103: Yes), it will progress to the process of S104.

  In S104, it is confirmed whether other brake control such as anti-skid control or trunk control is being performed. If other brake control is being performed (S104: Yes), if the failure detection is performed, the other control is affected. Therefore, this processing is terminated without performing the failure detection. If no other brake control is performed (S104: No), the process proceeds to S105.

  In S105, the wheel speed of the wheel subject to failure inspection is detected by a corresponding wheel speed sensor, and the first vehicle deceleration DV1 is obtained from the wheel speed by calculation. The first vehicle deceleration DV1 is temporarily stored in the RAM 43 and used in this failure detection process.

  Next, it is confirmed whether or not the first vehicle deceleration DV1 is within a predetermined range (S106). If the first vehicle deceleration DV1 is not within the predetermined range (S106: No), the present process is terminated without performing failure detection. . Thereby, when the vehicle deceleration is very small, it is possible to eliminate the possibility of erroneous detection without detecting an increase in the wheel speed of the target wheel. Further, when the vehicle deceleration is very large, it is possible to avoid the danger associated with the wheel speed increase of the target wheel due to the failure detection.

  On the other hand, when it is confirmed by the process of S106 that the first vehicle deceleration DV1 is within the predetermined range (S106: Yes), the second vehicle deceleration is determined from the wheel speed of the target wheel after a predetermined time from the process of S105. DV2 is calculated (S107). The second vehicle deceleration DV2 is temporarily stored in the RAM 43 and used in this failure detection process.

  Then, as in S106, it is confirmed whether or not the second vehicle deceleration DV2 is within a predetermined range (S108). If it is not within the predetermined range (S108: No), this process is performed without performing the failure detection. Exit. At this time, the lower limit of the predetermined range is set to the first vehicle deceleration DV1. When the braking force applied to the target wheel is increased, the vehicle deceleration increases, so that it can be determined whether the braking force applied to the target wheel is increased. And when 2nd vehicle deceleration DV2 is below 1st vehicle deceleration DV1, it is judged that it is not in a predetermined range (S108: No). On the other hand, if it is within the predetermined range (S108: Yes), the process proceeds to S109 to set the drive pattern and drive time of the W / C pressure to be applied to the target wheel when the failure detection is performed. Perform failure detection.

  In the processing of S109 to S112, a drive pattern of W / C pressure to be applied to the target wheel is set according to the drive pattern map 42c shown in FIG.

  First, in the process of S109, it is confirmed whether the second vehicle deceleration DV2 is equal to or less than a first predetermined value. Thereby, the case classification by the 2nd vehicle deceleration DV2 of the drive pattern map 42c shown to Fig.4 (a) can be performed.

  If the second vehicle deceleration DV2 is equal to or smaller than the first predetermined value (S109: Yes), then, the difference between the second vehicle deceleration DV2 and the first vehicle deceleration DV1 is obtained, and the difference is the second predetermined value. It is confirmed whether it is below the value (S110). Here, the difference between the second vehicle deceleration DV2 and the first vehicle deceleration DV1 represents the amount of change in the vehicle deceleration. Therefore, by the processing of S110, in the drive pattern map 42c shown in FIG. 4A, the amount of change in the vehicle deceleration (DV2-DV1) when the second vehicle deceleration DV2 is not more than the first predetermined value. Case classification can be performed.

  If the difference between the two vehicle decelerations DV2 and DV1 is equal to or smaller than the second predetermined value (S110: Yes), the drive pattern is set to “reduced pressure” based on the drive pattern map 42c (S111), and the process of S113 Migrate to

  On the other hand, when the second vehicle deceleration DV2 is larger than the first predetermined value (S109: No) and when the difference between the two vehicle decelerations DV2 and DV1 is larger than the second predetermined value (S110: No). Sets the drive pattern to “hold” based on the drive pattern map 42c (S112), and proceeds to the process of S113.

  Next, in the processing of S113 to S119, the drive time of the W / C pressure to be applied to the target wheel is set according to the drive time map 42d shown in FIG.

  First, in the process of S113, it is confirmed whether the second vehicle deceleration DV2 is equal to or smaller than a third predetermined value. If the second vehicle deceleration DV2 is equal to or smaller than a third predetermined value (S113: Yes), the process of S114 is performed. Migrate to If the second vehicle deceleration DV2 is greater than the third predetermined value (S113: No), the process proceeds to S117. Thereby, the case classification by the 2nd vehicle deceleration DV2 of the drive time map 42d shown in FIG.4 (b) can be performed.

  In the process of S114, a difference between the second vehicle deceleration DV2 and the first vehicle deceleration DV1 (that is, a change amount of the vehicle deceleration) is obtained, and it is confirmed whether the difference is equal to or smaller than a fourth predetermined value. By the process of S114, it is possible to perform the case classification based on the change amount (DV2-DV1) of the vehicle deceleration when the second vehicle deceleration DV2 is small in the driving time map 42d shown in FIG. 4B.

  When the difference between the two vehicle decelerations DV2 and DV1 is equal to or smaller than the fourth predetermined value (S114: Yes), the driving time is set to “T1” based on the driving time map 42d (S115). On the other hand, when the difference between the two vehicle decelerations DV2 and DV1 is larger than the fourth predetermined value (S114: No), the drive time is set to “T2” based on the drive time map 42d (S116).

  In S117, as in S114, the difference between the second vehicle deceleration DV2 and the first vehicle deceleration DV1 (that is, the amount of change in vehicle deceleration) is obtained, and the difference is equal to or less than the fourth predetermined value. Check if it exists. Thereby, in the drive time map 42d shown in FIG.4 (b), the case division by the amount (DV2-DV1) of the vehicle deceleration when the 2nd vehicle deceleration DV2 is large can be performed.

  When the difference between the two vehicle decelerations DV2 and DV1 is equal to or smaller than the fourth predetermined value (S117: Yes), the drive time is set to “T3” based on the drive time map 42d (S118). On the other hand, when the difference between the two vehicle decelerations DV2 and DV1 is larger than the fourth predetermined value (S117: No), the drive time is set to “T4” based on the drive time map 42d (S119).

  After one of the processes of S115 to S119, before driving and controlling the W / C pressure applied to the target wheel, the pre-drive wheel speed V1 is acquired from the wheel speed sensor (S120). This pre-drive wheel speed V1 is temporarily stored in the RAM 43 and referred to in later S123.

  Subsequently, the W / C pressure of the target wheel is controlled by driving the electromagnetic valves 21 to 28 of the hydraulic pressure control device 12 according to the driving pattern and the driving time set in the processing of S109 to S119 (S121). . The driving time is measured by a timer circuit 44. And after the drive time set by the process of S115-S119 is timed by the time measuring circuit 44, it progresses to the process of S122.

  In the process of S122, the post-drive wheel speed V2 of the target wheel is acquired from the wheel speed sensor. Then, the post-drive wheel speed V2 is compared with the pre-drive wheel speed V1 temporarily stored in the RAM 43 to confirm whether wheel acceleration has occurred on the acceleration side (S123). If it is determined that acceleration-side wheel acceleration has occurred (S123: Yes), the wheel speed is increasing as a result of the drive control in S121. “0” is set in the fall detection result flag 43b (S124). Then, the process proceeds to S126.

  On the other hand, if it is determined that no wheel acceleration is generated on the acceleration side (S123: N0), it is determined that “there is a failure” in the target wheel because the wheel speed continues to be reduced by the drive control of S121. Then, “1” is set in the failure detection result flag 43b (S125). Then, the process proceeds to S126.

  In the process of S126, the failure detection end flag 43a is set to “1”, and this process ends.

  In this way, by performing the failure detection process shown in FIG. 5, the W / C pressure applied to the target wheel is reduced for the time indicated by the drive time or held for that time. Then, the failure can be accurately detected by detecting the fluctuation of the wheel speed of the target wheel during that time. In addition, since it is possible to detect the failure of braking force from the fluctuation of the wheel speed subject to the failure inspection, the influence of wheel speed error that occurs when comparing the wheel speeds of two wheels as in the prior art is eliminated. can do. Therefore, it is possible to accurately detect the failure of the braking force.

  In the process of S108, the lower limit of the predetermined range is set to the first vehicle deceleration DV1, and when the second vehicle deceleration DV2 is at least larger than the first vehicle deceleration DV1, that is, given to the target wheel. When the braking force is increasing, the W / C pressure applied to the target wheel is reduced or maintained for the time indicated in the drive time by the processing after S109, so that there is no failure in the target wheel. For example, the wheel speed of the target wheel is reliably changed to the acceleration side by the reduction or holding of the W / C pressure. Therefore, failure detection can be performed reliably. Further, since the failure detection is executed when the braking force applied to the target wheel is increased, the failure detection can be performed if at least the W / C pressure applied to the target wheel is held. it can. Thereby, when control is performed so as to maintain the W / C pressure applied to the target wheel at the time of failure detection, compared to the case of controlling to decrease the W / C pressure applied to the target wheel, The degree of braking force reduction at the target wheel can be reduced. Therefore, the uncomfortable feeling felt by the passenger of the vehicle can be suppressed by executing the failure detection.

  Next, the EBD process executed by the ECU 14 will be described with reference to FIG. FIG. 6 is a flowchart showing the EBD processing. This process is executed when the CPU 41 starts up the EBD program 42b every predetermined time interval (for example, 10 milliseconds).

  In this process, first, it is determined whether an EBD control condition is satisfied (S201). For example, it is determined from the wheel speeds of the wheels FR, FL, RR, RL measured by the wheel speed sensor SE whether a predetermined slip has occurred in the rear wheels RR, RL. If a predetermined slip occurs in the rear wheels RR and RL, it is determined that the EBD control condition is satisfied, and otherwise, it is determined that the EBD control condition is not satisfied.

  If the EBD control condition is not satisfied (S201: No), the failure detection end flag 43a is set to “0” (S209). As a result, the failure detection process can be performed immediately before the EBD control condition is satisfied and the EBD control is performed. Also, the EBD control is terminated (S210), and the EBD process is terminated. Here, the EBD control condition is generally different between a start condition when the EBD control is not performed and an end condition when the EBD control is performed.

  On the other hand, if the EBD control condition is satisfied (S201: Yes), it is confirmed whether the failure detection end flag 43a is "1" (S202). Here, when the failure detection end flag 43a is “0” (S202: No), it is further confirmed whether or not the hydraulic pressure control device 12 is in the failure inspection drive (S203). If the failure inspection drive is not being performed (S203: No), a failure inspection target wheel is determined (S204). In the present embodiment, the right front wheel FR is designated, and then the failure detection program 42a is activated to execute the failure detection process (S205).

  On the other hand, when the failure inspection driving is being performed (S203: Yes), the processing of S204 is skipped and the failure detection processing is executed (S205). Then, the process proceeds to S206.

  In the process of S206, it is confirmed whether or not the failure detection end flag 43a is “1”. If the failure detection end flag 43a is “0” (S206: No), the failure detection has not ended, and thus the EBD process is temporarily ended. Even if the EBD processing is ended here, the confirmation processing (S202 and S206) of the failure detection end flag 43a can be performed again by the EBD processing at the next timing (for example, after 10 milliseconds).

  On the other hand, if the failure detection end flag 43a is “1” as a result of the confirmation by the process of S202 and the confirmation by the process of S206 (S202: Yes, S206: Yes), the failure is detected by the failure detection process. Since it is determined that the detection has been completed, it is then confirmed whether or not the failure detection result flag 43b in which the result of the failure detection is stored is “1” (S207).

  If the failure detection result flag 43b is “0” (S207: No), the front wheels FR and FL have not failed, and EBD control is performed (S208). Thereby, the increase in the W / C pressure of the rear wheels RR and RL is suppressed, and the rear wheels RR and RL can be prevented from slipping. Thereafter, the EBD process is terminated.

  On the other hand, if the failure detection result flag 43b is “1” (S207: Yes), the front wheels FR and FL have failed, so the processing of S209 (EBD control) is not performed. As a result, when the front wheels FR and FL are in a failure state, the vehicle can be safely stopped while increasing the W / C pressure applied to the rear wheels RR and RL. Then, this EBD process is terminated.

  Next, with reference to FIG. 7, the timing of each process and flag change in the EBD process (see FIG. 6) will be described. FIG. 7 is a timing chart during EBD processing. FIG. 7 shows an example when the front wheels (FR, FL) have failed and an example when the front wheels (FR, FL) are normal. Further, the vertical axis in FIG. 7 shows “EBD control condition” indicating whether or not the EBD control condition is satisfied, a failure detection end flag 43a, and “failure inspection” indicating whether or not the failure inspection driving is in progress. "Drive", failure detection result flag 43b, and "EBD control" indicating whether or not EBD control is being performed. On the other hand, the horizontal axis indicates time t.

  The “EBD control condition” represents a state where the EBD control condition is satisfied as “Hi” and a state where the EBD control condition is not satisfied as “Low”. In addition, “failure inspection driving” represents a state in which the failure inspection driving is being performed as “Hi”, and a state in which the failure inspection driving is not being performed as “Low”. Further, “EBD control” represents a state where the EBD control is performed as “Hi”, and a state where the EBD control is not performed as “Low”.

  First, when the front wheel (FR, FL) has failed, the above-described EBD processing (see FIG. 6) is started, and if the EBD control condition is satisfied in the processing of S201 in FIG. 6, the failure inspection driving is not performed. In S205 of FIG. 6, the failure detection process is executed, and the failure inspection drive is started. When the failure inspection drive ends, the failure detection result flag 43b is set to “1” by the failure detection process, and the failure detection end flag 43a is set to “1”. In the EBD process, when the failure detection end flag 43a is confirmed to be “1” in the process of S202 or S206 of FIG. 6, the contents of the failure detection result flag 43b are confirmed in the process of S207 of FIG. To do. In this case, since the failure detection result flag 43b is “1”, the EBD control is not performed, and the EBD process ends.

  On the other hand, when the front wheels (FR, FL) are normal, the EBD process (see FIG. 6) described above is started in the same manner as when the front wheels (FR, FL) have failed, and the EBD control condition is established in the process of S201 of FIG. Then, when the failure inspection drive is not performed, the failure detection process is executed in S205 of FIG. 6, and the failure inspection drive is started. When the failure inspection drive ends, the failure detection result flag 43b is set to “0” by the failure detection process, and the failure detection end flag 43a is further set to “1”. In the EBD process, it is confirmed in S202 or S206 in FIG. 6 that the failure detection end flag 43a is “1”, and then in the process in S207 in FIG. 6, the failure detection result flag 43b is set. When it is confirmed that the value is “0”, EBD control is performed and the EBD process is terminated.

  Next, the brake control device 1 according to the second embodiment will be described with reference to FIGS. 8 and 9. In the brake control device 1 according to the first embodiment described above, when the EBD control condition is satisfied, before the EBD control is performed, the right front wheel FR is used as a failure inspection target wheel and the front wheel pipe (first hydraulic circuit 18) is used. A case has been described in which the failure detection process is executed, and as a result, EBD control is performed if no failure is detected, and EBD control is not performed if a failure is detected. On the other hand, the brake control device 1 according to the second embodiment performs EBD control when the EBD control condition is satisfied, and the front wheel pipe (first liquid) with the right front wheel FR as a failure inspection target wheel during EBD control. The failure detection process of the pressure circuit 18) is executed. As a result of the failure detection process, if no failure is detected, the EBD control is continued. If a failure is detected, the EBD control is terminated.

  In addition, the whole structure of the brake control apparatus 1 in 2nd Embodiment is the same as the brake control apparatus 1 (refer FIG. 1) in 1st Embodiment, The electrical structure of ECU14 in 2nd Embodiment is a part. Except for a difference, it is the same as ECU14 (refer FIG. 2) in 1st Embodiment. Hereinafter, the same elements as those in the first embodiment will be denoted by the same reference numerals, illustration and description thereof will be omitted, and differences from the first embodiment will be described.

  In the brake control device 1 in the second embodiment, the difference from the brake device 1 in the first embodiment is that the EBD program 42b (see FIG. 2) is shown in FIG. 8 instead of the EBD processing shown in FIG. It is a point which is a program which makes CPU11 perform the EBD process in 2nd Embodiment shown.

  Although details will be described later with reference to FIG. 8, when the EBD program 42b in the second embodiment is executed by the CPU 41, the EBD control condition is satisfied when the EBD control is not being performed (for example, the rear wheel RR, When a predetermined slip occurs in RL), EBD control is once performed. Thereafter, the failure detection program 42a is executed during EBD control to detect the failure on the front wheels FR and FL. If it is determined that “no failure” is determined on the front wheels FR and FL, the EBD control is continued. If it is determined that “no failure” is determined on the front wheels FR and FL, the EBD control is terminated. The EBD program 42b is executed by the CPU 41 at predetermined time intervals (for example, 10 milliseconds).

  Unlike the first embodiment, the failure detection program 42a (see FIG. 2) is executed by the CPU 41 in the EBD program 42b during the EBD control as described above. Here, since the failure detection program 42a is executed during the EBD control, when the failure detection program 42a is executed, the W / C applied to the wheel cylinders 13c, 13d provided with the rear wheels RR, RL. The pressure increase is already suppressed. If a failure occurs on the front wheels FR and FL, the W / C pressure applied to the wheel cylinders 13a and 13b provided on the front wheels FR and FL is not increased. Failure detection by the detection program 42a needs to be executed regardless of whether or not the braking force applied to each wheel FR to RL is increasing.

  Therefore, in the failure detection program 42a in the second embodiment, the first implementation is performed when it is confirmed in the processing of S108 of the failure detection processing shown in FIG. 5 whether the second vehicle deceleration DV2 is within a predetermined range. As in the failure detection process in the embodiment, the lower limit of the predetermined range is not set to the first vehicle deceleration DV1, and the vehicle deceleration that can detect the increase in the wheel speed at the failure inspection target wheel is detected as in the process of S106. Is set as the lower limit of the predetermined range. Thereby, when the vehicle deceleration is very small, it is possible to eliminate the possibility of erroneous detection without detecting an increase in the wheel speed of the wheel subject to failure inspection.

  Further, since it is necessary to detect the failure regardless of whether or not the braking force applied to each wheel FR to RL is increasing, the control applied to each wheel FR to RL when the failure detection is performed. If the power is not increased, the wheel speed may not increase in the failure inspection target wheel simply by maintaining the W / C pressure applied to the failure inspection target wheel and applied to the multi-wheel cylinder. There is a possibility that the failure cannot be detected.

  Accordingly, in the brake control device 1 according to the second embodiment, the drive pattern of the W / C pressure applied to the multi-wheel cylinder provided on the failure inspection target wheel when performing the failure detection is fixed to “depressurization” and set. To do. That is, in the brake control device 1 in the second embodiment, the drive pattern map 42c is not used (or the drive pattern map 42c is not provided in the RAM 42), and in the failure detection process shown in FIG. Instead of the process, if it is confirmed that the second vehicle deceleration DV2 is within the predetermined range as a result of the process of S108 (S108: Yes), it is given to the wheel subject to the failure inspection when the failure is detected. The drive pattern of the W / C pressure is set to “reduced pressure”, and the process proceeds to S113.

  Further, in the failure detection program 42a in the second embodiment, this “other brake control” is used when it is confirmed whether other brake control is performed in the processing of S104 of the failure detection processing shown in FIG. Confirm by excluding EBD control. Thereby, even if it is during EBD control, if other brake control is not performed, it will be judged in the process of S104 that other brake control is not performed (S104: No). If other conditions (conditions determined by the processing of S106 and S108) are satisfied, failure detection is performed.

  The failure detection end flag 43a (see FIG. 2) in the second embodiment is different from the failure detection end flag 43a in the first embodiment in that “0” is set in the failure detection end flag 43a. . That is, in the second embodiment, when an ignition switch (not shown) is turned on, “0” is set as an initial value, and in the EBD process (see FIG. 8) executed by the EBD program 42b. Thus, in both cases when the EBD control is being performed and when the EBD control is not being performed, the EBD control condition is set to “0” (see S303 and S307 in FIG. 8). As a result, EBD control can be performed when the EBD control condition is satisfied, not during the EBD control (see S305 in FIG. 8), and after the EBD control is performed, the failure occurs. Detection processing (see FIG. 5) can be performed.

  Next, the EBD process in the second embodiment executed by the ECU 14 will be described with reference to FIG. FIG. 8 is a flowchart showing the EBD processing. This process is executed when the CPU 41 starts up the EBD program 42b every predetermined time interval (for example, 10 milliseconds).

  In this process, first, it is confirmed whether the EBD control is being performed (S301). This process is, for example, provided in the RAM 43 with an EBD control in-progress flag (not shown) that is turned on when EBD control is started and turned off when the EBD control is ended, and confirms the contents of the EBD control flag. Can be done by. That is, if the EBD control in-progress flag is on, it is determined that the EBD control is in progress. If the EBD control in-progress flag is off, it is determined that the EBD control is not in progress.

  As a result of the process of S301, when the EBD control is not being performed (S301: Yes), it is then confirmed whether the EBD control condition is satisfied (S302). The process of S302 is for determining the start of EBD control. If the EBD control is not being performed (S301: No) and the EBD control condition is not satisfied (S302: No), the failure detection end flag 43a is set to “0” (S303), and the EBD process is performed. finish. By the process of S303, the EBD control can be performed when the EBD control condition is satisfied and not during the EBD control, and the failure detection process is performed during the EBD control (see FIG. 5). Can be done.

  On the other hand, when the EBD control is not being performed (S301: No) and the EBD control condition is satisfied (S302: Yes), it is further confirmed whether the failure detection end flag 43a is “0” (S304). When the failure detection end flag 43a is “0” (S304: Yes), EBD control is performed (S305), and the EBD process is ended. Here, the process of S304 determines that the failure detection end flag 43a is “0” (S304: Yes) because the EBD control condition is not satisfied when the EBD control is not being performed. This is the time when the EBD control condition is established. Therefore, when the EBD control condition is not satisfied and the state shifts from the state where the EBD control condition is not satisfied to the state where the EBD control condition is satisfied, the EBD control is once started by the processing of S305.

  Thereby, the increase in the W / C pressure applied to the wheel cylinders 13c, 13d of the rear wheels RR, RL is suppressed, and the rear wheels RR, RL can be prevented from slipping. In the processing of S305, the EBD control in-progress flag provided in the RAM 43 is turned on in accordance with the EBD control. Thereby, it is possible to determine whether or not the EBD control is being performed in the process of S301.

  On the other hand, if the failure detection end flag 43a is not “0” (ie, “1”) as a result of the process of S304 (S304: No), the process of S305 is skipped and the EBD control is performed. Without performing this, the EBD processing is terminated. Here, the failure detection end flag 43a is determined to be “1” by the processing of S304 (S304: No) because the failure detection processing (S205) is performed during EBD control, as will be described later. If the failure detection end flag 43a is set to “1” and the failure detection processing results in the failure detection target wheel (front wheels FR, FL), it is determined that “there is a failure”. (S207: Yes), and the EBD control is terminated (S308). Therefore, by skipping the processing of S305 and not performing the EBD control, even if the EBD control condition is satisfied, if the front wheels FR and FL are in a failure state, W applied to the rear wheels RR and RL. The vehicle can be safely stopped while increasing the / C pressure.

  On the other hand, if the EBD control is being performed as a result of the process of S301 (S301: Yes), it is then confirmed whether the EBD control condition is satisfied (S306). However, the process of S306 is for determining the end of the EBD control. Note that the EBD control condition (EBD end condition) used in the process of S306 and the EBD control condition (S302) used for confirming whether the EBD control condition performed when the EBD control is not being performed (S301: No) are satisfied (S302). Generally, it is different from the EBD start condition.

  If the EBD control condition is not satisfied as a result of the process of S306 (S306: No), it is determined that the EBD end condition is satisfied, the failure detection end flag 43a is set to “0” (S307), and the EBD control is ended. (S308), and the EBD process ends. In the process of S308, the EBD control in-progress flag provided in the RAM 43 is turned off as the EBD control ends. Thereby, it is possible to easily determine whether or not the EBD control is being performed in the process of S301.

  On the other hand, if the EBD control condition is satisfied as a result of the process of S306 (S306: Yes), then the same process as the process of S202 to S207 executed in the EBD process (see FIG. 6) in the first embodiment is performed. Is called. That is, in the process of S202, it is confirmed whether the failure detection end flag 43a is “1”. If the failure detection end flag 43a is “0” (S202: No), the hydraulic pressure control device 12 further It is confirmed whether or not the defect inspection is being driven (S203). If the failure inspection drive is not being performed (S203: No), the failure inspection target wheel is determined to be the right front wheel FR (S204), the failure detection program 42a is activated, and the failure detection processing is executed (S205). ). On the other hand, when the failure inspection driving is being performed (S203: Yes), the processing of S204 is skipped and the failure detection processing is executed (S205).

  After the process of S205, it is confirmed whether or not the failure detection end flag 43a is “1” (S206). If the failure detection end flag 43a is “0” (S206: No), the failure detection is detected. Is not completed, the EBD control is continued (S208), and the EBD process is terminated. Thereby, the increase in the W / C pressure of the rear wheels RR and RL is suppressed, and the rear wheels RR and RL can be continuously prevented from slipping.

  On the other hand, if the failure detection end flag 43a is “1” as a result of the confirmation by the process of S202 and the confirmation by the process of S206 (S202: Yes, S206: Yes), the failure is detected by the failure detection process. Since it is determined that the detection has been completed, it is then confirmed whether or not the failure detection result flag 43b in which the result of the failure detection is stored is “1” (S207).

  If the failure detection result flag 43b is “1” (S207: Yes), the front wheels FR and FL have failed, so the process proceeds to S308, and the EBD in-control flag provided in the RAM 43 is set. At the same time, the EBD control is terminated. As a result, when the front wheels FR and FL are in a failed state, the EBD control is terminated, so that the vehicle can be safely stopped while increasing the W / C pressure applied to the rear wheels RR and RL. . Then, this EBD process is terminated.

  On the other hand, when the failure detection result flag 43b is “0” (S207: No), since the front wheels FR and FL have not failed, the EBD control is continued (S208), and the EBD process is terminated. Thereby, the increase in the W / C pressure of the rear wheels RR and RL is suppressed, and the rear wheels RR and RL can be continuously prevented from slipping.

  Next, with reference to FIG. 9, the timing of each process and flag change in the EBD process (see FIG. 8) will be described. FIG. 9 is a timing chart during EBD processing. FIG. 9 shows an example when the front wheels (FR, FL) have failed, an example when the front wheels (FR, FL) are normal, and a timing chart (see FIG. 7) at the time of EBD processing in the first embodiment. Is shown. In addition, the vertical axis of FIG. 9 shows “EBD control condition” indicating whether or not the EBD control condition is satisfied, a failure detection end flag 43a, and “failure inspection” indicating whether or not the failure inspection is being driven. "Drive", failure detection result flag 43b, and "EBD control" indicating whether or not EBD control is being performed. On the other hand, the horizontal axis indicates time t.

  First, when the front wheel (FR, FL) fails, the above-described EBD processing (see FIG. 8) is started, and when the EBD control condition is satisfied in the processing of S302 in FIG. EBD control is performed once by the processing of S305. Next, during EBD control, a failure detection process is executed by the process of S205 in FIG. 8, and a failure inspection drive is started. When the failure inspection drive ends, the failure detection result flag 43b is set to “1” by the failure detection process, and the failure detection end flag 43a is set to “1”.

  In the EBD process, when the failure detection end flag 43a is confirmed to be “1” in the process of S202 or S206 of FIG. 6, the contents of the failure detection result flag 43b are confirmed in the process of S207 of FIG. To do. In this case, since the failure detection result flag 43b is “1”, the EBD control is terminated by the processing of S308 in FIG. Further, while the EBD control condition is satisfied, the failure detection end flag 43a is held at “1”, and the EBD process is ended without performing the EBD control again by the branch of S304: No in FIG. To do.

  On the other hand, when the front wheels (FR, FL) are normal, the above-described EBD processing (see FIG. 8) is started as in the case of the front wheel (FR, FL) failure, and when the EBD control is not being performed, When the EBD control condition is established in the process, the EBD control is temporarily performed by the process of S305 in FIG. Then, during the EBD control, the failure detection process is executed by the process of S205 of FIG. 8, and when the failure inspection drive by that is completed, the failure detection result flag 43b is set to “0” by the failure detection process. Further, the failure detection end flag 43a is set to “1”. In the EBD process, it is confirmed in S202 or S206 in FIG. 6 that the failure detection end flag 43a is “1”, and then in the process in S207 in FIG. 6, the failure detection result flag 43b is set. If it is confirmed that the value is “0”, the EBD control is continued. Thereby, while the EBD control condition is satisfied, the EBD control is continuously performed.

  As described above, according to the brake control device 1 in the second embodiment, while the increase in the W / C pressure applied to the wheel cylinders 13c and 13d of the rear wheels RR and RL is suppressed by the EBD control. Since the W / C pressure applied to the wheel cylinder 13a of the right front wheel FR is controlled to be reduced for a predetermined time, a failure of the braking force of the front wheel is caused by the same action as the brake control device 1 in the first embodiment. Can be detected with high accuracy.

  In addition, since the EBD control suppresses the increase in the W / C pressure applied to the wheel cylinders 13c and 13d of the rear wheels RR and RL, the rear wheels RR and RL first move along with the load movement during braking. While it can be prevented from being locked, while the increase in the W / C pressure applied to the wheel cylinders 13c and 13d of the rear wheels RR and RL is suppressed by the EBD control, the front wheel side FR is detected by the failure detection process. When it is detected that FL is in a failure state, the EBD control is terminated, and the increase in the W / C pressure applied to the wheel cylinders 13c and 13d of the rear wheels RR and RL is not suppressed. As a result, when the front wheels FR and FL are in a failed state, the vehicle can be safely stopped while increasing the W / C pressure applied to the wheel cylinders 13c and 13d of the rear wheels RR and RL.

  Furthermore, after the increase in the W / C pressure applied to the wheel cylinders 13c and 13d of the rear wheels RR and RL is suppressed by the EBD control, the failure detection drive is performed and the failure detection is performed. When the EBD control condition is satisfied, the increase in the W / C pressure applied to the wheel cylinders 13c and 13d of the rear wheels RR and RL by the EBD control is not affected by the time taken to execute the failure detection. Suppression can be performed immediately. Alternatively, in order to immediately execute the EBD control, it is not necessary to execute the failure detection when the vehicle deceleration is not large enough or to execute the failure detection in a short time. Accuracy can be ensured. Therefore, the start of the suppression of the increase in the W / C pressure applied to the wheel cylinders 13c, 13d of the rear wheels RR, RL is delayed by the execution of the failure detection while reliably performing the failure detection, It is possible to suppress the rear wheels RR and RL from being locked.

  Although the present invention has been described based on the embodiments, the present invention is not limited to the above-described embodiments, and various improvements and modifications can be easily made without departing from the spirit of the present invention. Can be inferred.

  For example, in the above-described embodiment, the example in which the hydraulic pressure control device 12 is configured by so-called “front and rear piping” is shown, but this may be configured by “X piping”. That is, the wheel cylinder 13a attached to the right front wheel FR and the wheel cylinder 13d attached to the left rear wheel RL are connected to the first hydraulic circuit 18, and the second hydraulic circuit 19 is connected to the left front wheel FL. You may connect the wheel cylinder 13b with which the wheel cylinder 13b was mounted | worn, and the wheel cylinder 13c with which the right rear wheel RR was mounted | worn. In the above embodiment, the number of hydraulic circuits provided in the hydraulic control device 12 is two and the number of wheels is four. However, the present invention is not limited to this. Also good. Even in such a case, the failure detection process shown in FIG. 5 can accurately detect the failure of the braking force.

  Further, in the above embodiment, the failure detection processing timing is set at the time of starting the EBD control or during the EBD control. However, when the first braking is performed after the ignition switch is turned on, the vehicle is stopped for a certain time. It may be at the time of the first braking or at the time of all braking.

  Further, in the above embodiment, the case where the right front wheel FR is set as the failure inspection target wheel and the failure detection vehicle processing of the front wheel pipe is executed has been described, but the present invention is not necessarily limited thereto, and the failure inspection target is not necessarily limited thereto. The failure detection process may be executed by setting the left front wheel FL as a wheel. Also by this, it is possible to detect the failure of the front wheels FR and FL braked by the first hydraulic circuit 18, that is, the front wheel piping. Further, when the first braking is performed after the ignition switch is turned on, the right rear wheel RR or the left rear wheel RL may be set as the wheel to be inspected for the failure detection process. As a result, it is possible to detect the failure of the rear wheel RR, RL side, that is, the rear wheel piping, which is braked by the second hydraulic circuit 18.

  Further, in the above embodiment, the number of wheels subject to failure inspection is one, but a plurality of wheels equipped with wheel cylinders connected to the same hydraulic circuit are set as wheels subject to failure inspection, and these are simultaneously failed. Detection may be performed. In particular, in the case of the front and rear piping shown in FIG. 1, for example, if the failure detection is simultaneously performed on the right front wheel FR and the left front wheel FL, the same braking force is applied to the left and right wheels, so that the balance of the vehicle is maintained. Can do.

  Further, in the above embodiment, the failure detection is terminated after the failure detection is performed on one failure inspection target wheel. However, the wheel mounted with the wheel cylinder connected to another hydraulic circuit is also applied thereafter. Failure detection may be performed. Thereby, it is possible to detect the failure of the braking force due to the leakage of the brake fluid for the plurality of hydraulic circuits.

  Moreover, in the said embodiment, the drive pattern map 42c shown to Fig.4 (a) is an illustration, It is not restricted to this, You may use only vehicle deceleration as a determination condition, and the change of vehicle deceleration Only the amount may be used. For example, the drive pattern may be set to “depressurization” when the wheel speed is equal to or lower than a first predetermined value, and the drive pattern may be set to “hold” when larger than the first predetermined value. Even with this setting, it is possible to detect the failure of the braking force safely and reliably while suppressing the uncomfortable feeling felt by the passengers of the vehicle. Further, a plurality of determination threshold values may be provided so that the drive pattern can be set finely.

  In the above embodiment, the drive time map 42d shown in FIG. 4B is an example, and the present invention is not limited to this. Only the vehicle deceleration may be used as the determination condition, or the vehicle deceleration changes. Only the amount may be used. Also, a plurality of determination threshold values may be provided so that the driving time and driving pattern can be set finely.

  Further, in the above embodiment, the case where the drive pattern and drive time of the W / C pressure to be applied to the target wheel are set based on the drive pattern map 42c and the drive time map 42d when the failure detection is performed. Although described above, the present invention is not necessarily limited thereto, and only one of the drive pattern and the drive time may be set based on one of the drive pattern map 42c and the drive time map 42d. . Further, without using these maps, the drive pattern and the drive time of the W / C pressure to be applied to the target wheel when the failure detection is performed may be fixed.

  Moreover, in the said embodiment, although the example which provides the braking force to each wheel using the hydraulic pressure of brake fluid as a pressure source was shown as the brake control apparatus 1, the pressure source of braking force is not restricted to the hydraulic pressure of brake fluid. Any may be used. For example, a braking force may be applied to each wheel using air pressure as a pressure source.

It is the schematic diagram which showed typically the whole structure of the brake control apparatus in 1st Embodiment of this invention. It is the block diagram which showed the electric structure of ECU. It is explanatory drawing explaining the failure detection principle of the failure detection program at the time of making a target wheel into a right front wheel, (a) is a figure when the right front wheel FR has not failed, (b) is a right front wheel. It is a figure in case FR has failed. (A) is the schematic diagram which showed typically the content of the drive pattern map, (b) is the schematic diagram which showed typically the content of the drive time map. It is a flowchart which shows a failure detection process. It is a flowchart which shows an EBD process. It is a timing chart at the time of EBD processing. It is a flowchart which shows the EBD process in 2nd Embodiment of this invention. It is a timing chart at the time of EBD processing.

Explanation of symbols

1 Brake control devices 13a to 13d Wheel cylinder (an example of braking force applying means)
14 ECU
41 CPU
FR Front right wheel (example of wheel, example of front wheel)
FL Left front wheel (example of wheel, example of front wheel)
RR Right rear wheel (example of wheel, example of rear wheel)
RL Left rear wheel (an example of a wheel, an example of a rear wheel)
SE wheel speed sensor (an example of wheel speed detection means)
S105, S107 (an example of deceleration calculation means)
S110, S114, S117 (an example of deceleration change calculation means)
S121 (an example of braking force inspection means)
S125 (an example of failure detection means)
S207: Yes (an example of rear wheel braking force suppression control prohibiting means)
S208, S305 (an example of rear wheel braking force suppression control means)
S308 (an example of rear wheel braking force suppression control ending means)

Claims (8)

Braking force applying means (13a to 13d) for applying a braking force to each of a plurality of wheels (FR, FL, RR, RL) provided in the vehicle;
The braking force applied to predetermined failure inspection target wheels (FR, FL, RR, RL) within a period during which the braking force is applied to each wheel by the braking force applying means (13a to 13d) is predetermined. A braking force inspection means (41, 41) that inspects the braking force of the failure inspection target wheel (FR, FL, RR, RL) by giving and controlling the inspection drive pattern so that the time is reduced or maintained for a predetermined time. S121)
Wheel speed detection means (SE) for detecting a wheel speed that is a rotation speed of the wheel for the failure inspection target wheel (FR, FL, RR, RL),
Detected by the wheel speed detecting means (SE) while inspecting the braking force applied to the failure inspection object wheels (FR, FL, RR, RL) by the braking force inspection means (41, S121). When the wheel speed does not change on the acceleration side, a failure is detected in which a braking force is not applied to the failure inspection target wheel (FR, FL, RR, RL). A brake control device comprising detection means (41, S125).   The braking force inspecting means (41, S121) has the failure detection target wheels (FR, FR) within a period in which the braking force applied to each wheel is increased by the braking force applying means (13a to 13d). FL, RR, RL) is applied with the driving pattern for inspection and controlled to inspect the braking force of the failure inspection target wheel (FR, FL, RR, RL). Item 4. The brake control device according to item 1. Braking force applying means (13a to 13d) for applying a braking force to each of a plurality of wheels (FR, FL, RR, RL) having front wheels (FR, FL) and rear wheels (RR, RL) provided in the vehicle. )When,
Rear wheel braking force suppression control means (41, S208) for suppressing an increase in braking force applied to the rear wheels (RR, RL);
Then, before suppressing the increase of the braking force applied to the rear wheels (RR, RL) by the rear wheel braking force suppression control means (41, S208), each wheel ( (FR, FL, RR, RL) The braking force applied to at least one of the front wheels (FR, FL) is reduced or maintained for a predetermined time within a period during which the braking force applied to FR, FL, RR, RL) is increased. Braking force inspection means (41, S121) for inspecting the braking force of the front wheels (FR, FL) by giving and controlling the inspection drive pattern as described above,
Wheel speed detection means (SE) for detecting the wheel speed, which is the rotational speed of the wheel, for the front wheels (FR, FL) to which the braking force controlled by the braking force inspection means (41, S121) is applied;
While the braking force applied to the front wheels (FR, FL) is inspected by the braking force inspection means (41, S121), a change on the acceleration side occurs in the wheel speed detected by the wheel speed detection means (SE). A failure detection means (41, S125) for detecting a failure state in which no braking force is applied to the front wheels (FR, FL) if not seen;
When the failure detection means (41, S125) detects that the front wheels (FR, FL) are in a failure state, the rear wheel braking force suppression control means (41, S208) uses the rear wheels (RR, And a rear wheel braking force suppression control prohibiting means (41, S207: Yes) for prohibiting suppression control of an increase in braking force applied to (RL). Braking force applying means (13a to 13d) for applying a braking force to each of a plurality of wheels (FR, FL, RR, RL) having front wheels (FR, FL) and rear wheels (RR, RL) provided in the vehicle. )When,
Rear wheel braking force suppression control means (41, S305) for suppressing an increase in braking force applied to the rear wheels (RR, RL);
At least one of the front wheels (FR, FL) while the increase control of the braking force applied to the rear wheels (RR, RL) is controlled by the rear wheel braking force suppression control means (41, S305). Braking force inspection means (41, S121) for inspecting the braking force of the front wheels (FR, FL) by giving and controlling an inspection drive pattern so as to reduce the braking force applied to the vehicle for a predetermined time;
Wheel speed detection means (SE) for detecting the wheel speed, which is the rotational speed of the wheel, for the front wheels (FR, FL) to which the braking force controlled by the braking force inspection means (41, S121) is applied;
While the braking force applied to the front wheels (FR, FL) is inspected by the braking force inspection means (41, S121), a change on the acceleration side occurs in the wheel speed detected by the wheel speed detection means (SE). A failure detection means (41, S125) for detecting a failure state in which no braking force is applied to the front wheels (FR, FL) if not seen;
When the failure detection means (41, S125) detects that the front wheels (FR, FL) are in a failure state, the rear wheel braking force suppression control means (41, S305) causes the rear wheels (RR, And a rear wheel braking force suppression control ending means (41, S308) for ending the suppression control of an increase in braking force applied to (RL). Comprising deceleration calculation means (41, S107) for calculating vehicle deceleration from the wheel speed detected by the wheel speed detection means (SE);
The braking force inspection means (41, S121) reduces the braking force when the vehicle deceleration calculated by the deceleration calculation means (41, S107) is less than or equal to a first predetermined value, and otherwise 4. The brake control device according to claim 1, wherein control is performed so as to maintain the braking force. Deceleration calculation means (41, S105, S107) for calculating vehicle deceleration from the wheel speed detected by the wheel speed detection means (SE);
A deceleration change calculating means (41, S110) for calculating a temporal change amount of the vehicle deceleration from the vehicle deceleration calculated by the deceleration calculating means (41, S105, S107);
The braking force inspection means (41, S121) has a vehicle deceleration calculated by the deceleration calculation means (41, S107) equal to or less than a first predetermined value, and the deceleration change calculation means (41, S110). If the temporal change amount of the vehicle deceleration calculated in step) is less than or equal to the second predetermined value, the braking force is decreased, and in other cases, the control is performed to maintain the braking force. The brake control device according to any one of claims 1 to 3, wherein Comprising deceleration calculation means (41, S107) for calculating vehicle deceleration from the wheel speed detected by the wheel speed detection means (SE);
The braking force inspection means (41, S121) reduces or maintains the braking force when the vehicle deceleration calculated by the deceleration calculation means (41, S107) is less than or equal to a third predetermined value. The brake control device according to any one of claims 1 to 4, wherein the vehicle deceleration is longer than a time when the vehicle deceleration is larger than a third predetermined value. Deceleration calculation means (41, S105, S107) for calculating vehicle deceleration from the wheel speed detected by the wheel speed detection means (SE);
Deceleration change calculating means (41, S114, S117) for calculating a temporal change amount of the vehicle deceleration from the vehicle deceleration calculated by the deceleration calculating means (41, S105, S107);
The braking force inspection means (41, S121) is configured to control the braking force when the temporal change amount of the vehicle deceleration calculated by the deceleration change calculation means (41, S114, S117) is equal to or less than a fourth predetermined value. 5. The time for reducing or maintaining the power is made longer than the time when the temporal change amount of the vehicle deceleration is larger than a fourth predetermined value. 6. Brake control device.

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