JP2010064658A - Brake control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brake control device capable of performing fail-safe in motor failure by an inexpensive and simple constitution in a system using a brushless motor. <P>SOLUTION: The brake control device 10 feeds an operation fluid to a wheel cylinder through a pump 34 driven with the motor 32, i.e., the three-phase brushless motor to generate brake force. ECU 200 functions as a failure detection means and a pressure-reduction control means. When the ECU 200 detects an energization failure of the motor 32, control is performed such that a pressure-boosting valve 40, i.e., a delivery side of the pump 34, is controlled to open, a hydraulic pressure is reduced to a fail motor drive allowance load value to continue the drive of the motor 32. Further, when the ECU200 detects the energization failure, rotation torque is adjusted such that the motor 32 is rotated under load in the fail motor drive allowance load value to continue the drive of the motor 32. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an improvement in fail-safe technology when a pump for pressurizing hydraulic fluid that generates a braking force fails in a brake control device, particularly in a system capable of assisting braking force.

  2. Description of the Related Art Conventionally, there is known a brake control device that applies a braking force to a vehicle by generating a hydraulic pressure in a hydraulic circuit according to an operation force of a brake pedal and supplying the hydraulic pressure to a wheel cylinder of each wheel through a pipe. (For example, refer to Patent Document 1).

The hydraulic circuit includes a reservoir tank that stores brake fluid (operating fluid) and a pump that pumps the brake fluid from the reservoir tank. An electromagnetic valve such as a pressure increasing valve or a pressure reducing valve is provided between the wheel cylinder of each wheel and the pump. The brake control device controls the fluid pressure by adjusting the supply and discharge amount of the brake fluid to the wheel cylinders by controlling the opening and closing of these solenoid valves. A braking force suitable for the driving condition is applied.
JP 2007-216946 A

  The driving of the pump in the brake control device as described above is generally performed by an electric motor. As an electric motor, use of a brush motor or a brushless motor can be considered.

  By the way, when using an electric motor, when a motor fails, since an appropriate motor cannot be driven, it is necessary to improve fail-safe property. In the case of a brush motor, since a motor relay or the like used for a power supply system is relatively inexpensive, it is conceivable to prepare a plurality of power supply systems for failsafe. However, the brush motor has a problem that the durability such as wear of the brush is inferior to the brushless motor due to its structure. On the other hand, brushless motors have high durability because there are no brushes that are worn parts, but the motor drive circuit is more expensive than brush motors, and providing more than one is disadvantageous in terms of cost and size, compared to brush motors. It becomes difficult to take advantage of the durability.

  Therefore, it is desired to propose a brake control device that can implement fail-safe in a highly durable brushless motor with a low cost and simple configuration.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a brake control device that can implement fail-safe at the time of motor failure with a low cost and simple configuration in a system using a brushless motor. is there.

  In order to solve the above problems, an aspect of the present invention is a brake control device that discharges hydraulic fluid by a pump driven by a brushless motor and supplies the hydraulic pressure of the hydraulic fluid to a wheel cylinder to generate a braking force. And a failure detection means for detecting an energization failure to the brushless motor, and when the failure detection means detects an energization failure, the hydraulic pressure on the discharge side of the pump is reduced to a fail motor drive allowable load value. Pressure reduction control means for continuing to drive the brushless motor.

  According to this aspect, when the fail detection means detects the energization failure, the hydraulic pressure on the discharge side of the pump is reduced to the fail motor drive allowable load value, so the load when the brushless motor is about to rotate can be reduced. . That is, when the rotor of the brushless motor rotates, the rotation can be continued by the inertial force. As a result, even when an energization failure occurs, the hydraulic pressure of the hydraulic fluid can be increased to some extent, and a braking force can be generated when necessary. The fail motor drive allowable load value can be determined in advance by a test or the like based on the characteristics of the brushless motor, and is a load value that allows the brushless motor to rotate even if it is not smooth.

  Further, in the above aspect, when the fail detection unit detects an energization failure, a torque adjustment unit may be included that adjusts the rotational torque so that the brushless motor rotates under a load value that allows the fail motor to be driven. . According to this aspect, since the brushless motor is controlled so that the brushless motor continues to rotate during the energization failure, the reliability of rotation continuity can be improved.

  Further, in the above aspect, the torque adjusting means adjusts the torque so as to generate a passing-over torque that rotates over the dead point where the theoretical advance angle of the rotor of the brushless motor becomes zero due to the inertial force of the rotor. May be. According to this aspect, torque control is positively performed in a portion where no failure occurs. As a result, since the dead point can be overcome efficiently and reliably, the reliability of rotation continuity can be improved.

  In the above aspect, the torque adjusting means may increase the duty ratio to a value at which the overcoming torque is generated in the front phase in the rotational direction with respect to the phase corresponding to the dead point. According to this aspect, since the inertial force of the rotor can be increased before the dead point of the rotor of the brushless motor in the energized fail state, the dead point can be overcome and the rotation of the rotor can be resumed. Further, when the rotor of the brushless motor in the energized fail state is rotating, the inertial force can be increased before the dead point, so that the rotation continuity of the rotor can be improved.

  In the above aspect, the torque adjusting means may control the phase other than the phase corresponding to the dead point to cause the rotor to rotate forward and reverse to generate the overcoming torque. According to this aspect, when the rotor of the brushless motor in the energized fail state has stopped rotating, the rotor is swung so that the rotor rotates in the forward and reverse directions using the phase that does not cause the energized fail, thereby reducing the inertia force of the rotor. Can rise. Then, when the inertial force enough to overcome the dead point is generated, if the control is performed so as to rotate in one direction, the dead point can be overcome and the rotation of the rotor can be resumed.

  According to the brake control device of the present invention, in a system using a brushless motor, fail-safe for continuing the rotation of the rotor even when energization failure occurs in the motor can be implemented with a low cost and simple configuration.

  Hereinafter, an embodiment of the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings.

  The brake control apparatus of this embodiment discharges hydraulic fluid by a pump driven by a brushless motor. Then, the hydraulic pressure of the hydraulic fluid is supplied to the wheel cylinder to generate a braking force in the brake device. The brake control device includes a failure detection means and a pressure reduction control means. When the fail detection means detects the energization failure of the brushless motor, the pressure reduction control means controls the pressure on the discharge side of the pump to the fail motor drive allowable load value so that the rotation of the motor can be continued. In addition, the brake control device includes a torque adjustment unit, and adjusts the rotational torque so that the brushless motor rotates under the allowable load value of the fail motor when the failure detection unit detects an energization failure. Then, control is performed so that the rotation of the motor can be continued.

  FIG. 1 is a system diagram showing a brake control device according to an embodiment of the present invention centering on its hydraulic circuit.

  The brake control device 10 constitutes an electronically controlled brake system (ECB) for a vehicle, and according to the operation of the brake pedal 12 by the driver and for various controls for stabilizing the traveling of the vehicle. It controls the four-wheel brake of a vehicle independently and optimally. The brake pedal 12 is connected to a master cylinder 14 that sends out brake fluid as hydraulic fluid in response to a depression operation by the driver. The brake pedal 12 is provided with a stroke sensor 46 for detecting the depression stroke. Further, a reservoir tank 26 is connected to the master cylinder 14, and a reaction force corresponding to the operating force of the brake pedal 12 by the driver is applied to one output port of the master cylinder 14 via the on-off valve 23. A stroke simulator 24 to be created is connected. The on-off valve 23 is a normally closed solenoid valve that is closed when not energized and is switched to an open state when an operation of the brake pedal 12 by the driver is detected.

  A brake fluid pressure control pipe 16 for the right front wheel is connected to one output port of the master cylinder 14, and the brake fluid pressure control pipe 16 is for the right front wheel that applies a braking force to the right front wheel (not shown). Connected to the wheel cylinder 20FR. Further, a brake fluid pressure control pipe 18 for the left front wheel is connected to the other output port of the master cylinder 14, and the brake fluid pressure control pipe 18 applies a braking force to the left front wheel (not shown). It is connected to a wheel cylinder 20FL for the front wheels. A right electromagnetic on-off valve 22FR is provided in the middle of the brake fluid pressure control pipe 16 for the right front wheel, and a left electromagnetic on-off valve 22FL is provided in the middle of the brake fluid pressure control pipe 18 for the left front wheel. Yes. The right solenoid on-off valve 22FR and the left solenoid on-off valve 22FL are both normally open solenoid valves that are open when de-energized and that are switched to the closed state when the operation of the brake pedal 12 by the driver is detected. is there. Hereinafter, the right electromagnetic on-off valve 22FR and the left electromagnetic on-off valve 22FL will be collectively referred to as “the on-off valve 22” as appropriate.

  A right master pressure sensor 48FR for detecting the master cylinder pressure on the right front wheel side is provided in the middle of the brake fluid pressure control pipe 16 for the right front wheel. Is provided with a left master pressure sensor 48FL for measuring the master cylinder pressure on the left front wheel side. In the brake control device 10, when the brake pedal 12 is depressed by the driver, the stroke operation amount is detected by the stroke sensor 46. Further, the depressing operation force (depressing force) of the brake pedal 12 can also be obtained from the master cylinder pressure detected by the right master pressure sensor 48FR and the left master pressure sensor 48FL. As described above, it is preferable from the viewpoint of fail-safe that the master cylinder pressure is monitored by the two pressure sensors 48FR and 48FL on the assumption of the failure of the stroke sensor 46. Hereinafter, the right master pressure sensor 48FR and the left master pressure sensor 48FL are collectively referred to as “master pressure sensor 48” as appropriate.

  On the other hand, one end of a hydraulic pressure supply / discharge pipe 28 is connected to the reservoir tank 26, and a suction port of a pump 34 driven by a motor 32 is connected to the other end of the hydraulic pressure supply / discharge pipe 28. Yes. The discharge port of the pump 34 is connected to a high-pressure pipe 30 that forms a high-pressure passage, and an accumulator 50 and a relief valve 53 are connected to the high-pressure pipe 30. The accumulator 50, the pump 34, and the motor 32 constitute a power hydraulic pressure source capable of accumulating the hydraulic pressure of the brake fluid. When the suction port of the pump 34 is not driven, the communication with the hydraulic pressure supply / discharge pipe 28 is substantially blocked. In the present embodiment, a gear pump that is rotationally driven by the motor 32 can be employed as the pump 34. For example, a three-phase brushless motor is used as the motor 32, and so-called PWM control is performed.

  Between the pump 34 and the accumulator 50, an accumulator cut valve 54 constituted by a normally open electromagnetic valve is provided. The accumulator 50 stores brake fluid whose internal hydraulic pressure (hereinafter referred to as “accumulator pressure”) is increased to a predetermined setting range (for example, about 8 to 12 MPa) by the pump 34. The valve outlet of the relief valve 53 is connected to the hydraulic pressure supply / discharge pipe 28. When the hydraulic pressure in the high pressure pipe 30 rises abnormally and reaches, for example, about 25 MPa, the relief valve 53 opens and the high pressure brake fluid is discharged. Is returned to the reservoir tank 26 via the hydraulic supply / discharge pipe 28. In addition, when accumulator 50 does not need pressure accumulation or when it is not necessary to supply hydraulic pressure to the pressure increasing valves 40FR, 40FL, 40RR, 40RL, the accumulator cut valve 54 may be controlled to be closed. By doing in this way, you may make it avoid exposing the high pressure pipe 30 and the pressure increase valves 40FR, 40FL, 40RR, and 40RL to a high pressure load. The high-pressure pipe 30 is provided with an accumulator pressure sensor 51 that detects the hydraulic pressure of the internal brake fluid (equal to the accumulator pressure in this embodiment).

  The high pressure pipe 30 is connected to the right front wheel wheel cylinder 20FR, the left front wheel wheel cylinder 20FL, the right rear wheel wheel cylinder 20RR, and the left rear wheel through the pressure increasing valves 40FR, 40FL, 40RR, 40RL. It is connected to the cylinder 20RL. Hereinafter, the wheel cylinders 20FR to 20RL will be collectively referred to as “wheel cylinders 20”, and the pressure increase valves 40FR to 40RL will be appropriately collectively referred to as “pressure increase valves 40”. The pressure increasing valve 40 is a normally closed electromagnetic flow control valve (linear valve) that is closed when not energized and is used for pressure increasing of the wheel cylinder 20 as necessary. A disc brake unit is provided for each wheel of the vehicle (not shown), and each disc brake unit generates a braking force by pressing the brake pad against the disc by the action of the wheel cylinder 20. In the example of FIG. 1, a case where the pressure increasing valve 40 is a normally closed electromagnetic flow control valve is shown, but a normally open type electromagnetic flow control valve is used by changing the control method of the pressure increasing valve 40. Is also possible. It is also possible to use a drum brake unit instead of the disc brake unit.

  Further, the wheel cylinder 20FR for the right front wheel and the wheel cylinder 20FL for the left front wheel are connected to the hydraulic pressure supply / discharge pipe 28 via the pressure reducing valve 42FR or 42FL, respectively. The pressure reducing valves 42FR and 42FL are normally closed electromagnetic flow control valves (linear valves) used for pressure reduction of the wheel cylinders 20FR and 20FL as necessary. On the other hand, the wheel cylinder 20RR for the right rear wheel and the wheel cylinder 20RL for the left rear wheel are connected to the hydraulic pressure supply / discharge pipe 28 via a pressure reducing valve 42RR or 42RL which is a normally open electromagnetic flow control valve. Yes. Hereinafter, the pressure reducing valves 42FR to 42RL are collectively referred to as “pressure reducing valve 42” as appropriate.

  In the vicinity of the wheel cylinders 20FR to 20RL for the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel, a cylinder pressure that detects a wheel cylinder pressure that is a pressure of a brake fluid acting on the corresponding wheel cylinder 20 is detected. Sensors 44FR, 44FL, 44RR and 44RL are provided. Hereinafter, the cylinder pressure sensors 44FR to 44RL are collectively referred to as “cylinder pressure sensor 44” as appropriate.

  The right electromagnetic on-off valve 22FR and the left electromagnetic on-off valve 22FL, the pressure increasing valves 40FR to 40RL, the pressure reducing valves 42FR to 42RL, the pump 34, the accumulator 50, and the like constitute the hydraulic actuator 80 of the brake control device 10. The hydraulic actuator 80 is controlled by an electronic control unit (hereinafter referred to as “ECU”) 200. The ECU 200 includes a CPU that executes various arithmetic processes, a ROM that stores various control programs, a RAM that is used as a work area for data storage and program execution, an input / output interface, a memory, and the like. In the present embodiment, the ECU 200 functions as a “decompression control unit” and a “torque adjustment unit”. In another embodiment, “depressurization control means” and “torque adjustment means” may be provided separately from the ECU 200.

  Although details are not shown, the ECU 200 includes cylinder pressure sensors 44FR, 44FL, 44RR, 44RL for the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel, respectively, in the wheel cylinder 20FR of the right front wheel. The pressure signal, the pressure signal in the left front wheel wheel cylinder 20FL, the pressure signal in the right rear wheel wheel cylinder 20RR, and the pressure signal in the left rear wheel wheel cylinder 20RL are input. The ECU 200 also receives a signal indicating the depression stroke of the brake pedal 12 from the stroke sensor 46, a signal indicating the master cylinder hydraulic pressure from the right master pressure sensor 48FR and the left master pressure sensor 48FL, and an accumulator pressure from the accumulator pressure sensor 51. The signal shown is input.

  The ROM of ECU 200 stores a predetermined braking control flow. The ECU 200 has a block for acquiring a target braking amount, and calculates the target braking amount of the vehicle based on the stroke signal and the master cylinder hydraulic pressure signal. Then, the ECU 200 calculates the target wheel cylinder hydraulic pressure of each wheel based on the calculated target braking amount, and the pressure increasing valve 40 and the pressure reducing valve 42 so that the wheel cylinder hydraulic pressure of each wheel becomes the target wheel cylinder hydraulic pressure. To control.

  The pump 34 driven by the motor 32 draws up the brake fluid from the reservoir tank 26 through the hydraulic pressure supply / discharge pipe 28 and accumulates the brake fluid at high pressure in the accumulator 50. The high hydraulic pressure of the accumulator 50 is supplied to each wheel cylinder 20 by opening / closing the pressure increasing valve 40 in accordance with the target wheel cylinder hydraulic pressure. In addition, when executing automatic stabilization control such as ABS control for stabilizing the running of the vehicle, the ECU 200 controls opening / closing of the pressure increasing valve 40 and the pressure reducing valve 42, and applies high-pressure brake fluid from the accumulator 50 to each wheel. Supply to the cylinder 20 to control the operation state.

  When the brake pedal 12 is depressed or high fluid pressure brake fluid is consumed from the accumulator 50 by ABS control, the ECU 200 operates the motor 32 so that the pressure of the accumulator 50 is always within the control range. The brake fluid is driven and accumulated in the accumulator 50 at a high pressure. This operation is called “pressure accumulation operation”. This pressure accumulation operation is automatically executed according to the detection value of the accumulator pressure sensor 51.

  FIG. 2 is an explanatory diagram illustrating a schematic configuration of the motor 32 configured by the three-phase brushless motor used in the present embodiment and a relationship with the ECU 200. In the motor 32 of this embodiment, the U phase 56u, the V phase 56v, and the W phase 56w are star-connected. Then, the voltage of the power source 60 is supplied to each phase by switching of the FET in the motor driver 58 that operates based on the control signal from the ECU 200, and the rotor of the motor 32 is rotated. The structure of the three-phase brushless motor and the configuration of the motor driver 58 are publicly known, and detailed description thereof is omitted.

  By the way, in the case of the brake control device 10 using the motor 32 that is a three-phase brushless motor configured as described above, it is normal if any one of the U phase 56u, the V phase 56v, and the W phase 56w causes a conduction failure. Can not rotate properly. In particular, when accumulating the accumulator 50, since the accumulator 50 side is at a high pressure, the rotation load of the motor 32 is high, and there is a high possibility that the rotation will stop if there is an energization failure even in one phase. Similarly, since the pressure increasing valve 40 is a normally closed electromagnetic flow control valve, the pressure is high during non-braking, so the rotation load of the motor 32 is high, and there is a possibility that the rotation will stop if there is an energization failure even in one phase. high. The energization failure can be in a state in which no current substantially flows due to disconnection of the coils constituting each phase, malfunction of the motor driver 58, or the like. In such a case, a sufficient braking force cannot be generated when necessary in the ECB system, and the braking force by the hydraulic pressure generated by the master cylinder 14 at the time of fail-safe is relied on, and a large pedaling force is applied to the operation of the brake pedal 12. This may impair driving comfort.

  Therefore, the brake control device 10 of the present embodiment controls the hydraulic actuator 80 and the motor driver 58 so that even if an energization failure occurs in the motor 32, if the failure is one phase, the motor 32 continues to rotate. The braking force can be generated by the ECB system.

  FIG. 3 is a flowchart for explaining fail-safe control during energization failure of the motor 32 in the present embodiment.

  The fail-safe control of the motor 32 ends when the ignition switch is OFF (IG OFF) (N in S100). Further, when the ECB system is not activated, that is, when the braking force control is performed only by the hydraulic pressure generated in the master cylinder 14 (N in S102), the process ends. Similarly, when no energization failure has occurred in the motor 32 (N in S104), the process ends. The ECU 200 can confirm the ON / OFF of the ignition switch based on information from a sensor provided in the ignition switch, and whether the ECB is activated can be confirmed by the control state of the ECU 200 itself. Further, whether or not an energization failure has occurred in the motor 32 can be confirmed by detecting whether or not the current value of each phase provided from the motor driver 58 is in accordance with the control.

  When the IG is ON (Y in S100), the ECB is being activated (Y in S102), and an energization failure has occurred in the motor 32 (Y in S104), the ECU 200 causes an energization failure in only one phase. Is detected based on the information provided from the motor driver 58. At this time, if the energization failure is not one phase (N in S106), that is, if an energization failure has occurred in two or more phases, the ECU 200 determines that the motor 32 is seriously damaged. A message is displayed on the console panel of the driver's seat indicating that the motor 32 has failed and the ECB system can no longer operate, a voice or warning sound is given to the driver, and a prompt prompt repair / inspection message is issued. The provided error processing is executed (S108).

  On the other hand, when the energization failure occurs only in one phase (Y in S106), the ECU 200 determines that the fail-safe process of the motor 32 is possible, closes the accumulator cut valve 54, and increases the pressure increasing valve. 40 is opened by a predetermined amount (S110). By closing the accumulator cut valve 54, it is possible to prevent the pump 34 and the accumulator 50 from being disconnected and a high pressure load from being applied to the pump 34. Further, by opening the pressure increasing valve 40 by a predetermined amount, the brake fluid leaks from the pressure increasing valve 40 and is returned to the reservoir tank 26, so that a high pressure load is prevented from being applied to the pump 34. That is, the rotational load of the motor 32 is reduced. In this way, by reducing the hydraulic pressure on the discharge side of the pump 34 to a load value that permits driving of the failed motor 32 (failure motor drive allowable load value), the motor 32 causing an energization failure as will be described later. When the rotor is rotating with inertial force, the inertial force rotation is continued. Further, when the rotor of the motor 32 causing the energization failure is stopped, the rotation is facilitated. The fail motor drive allowable load value can be determined in advance by a test or the like according to the characteristics of the motor 32, and is a load value that can rotate even if the motor 32 is not smooth. For example, FIG. 4A shows the relationship between the current value applied to the pressure increasing valve 40 and the opening or flow rate of the pressure increasing valve 40. The current value Ia can be set to an opening smaller than the opening when the braking force generated during normal traveling is obtained. As will be described later, when the motor 32 in the failed state continues to rotate, it is necessary to consider heat generation during continuous rotation. Therefore, in the present embodiment, the motor 32 is driven with a duty ratio of about 5%, for example. In other words, the current value Ia that realizes the fail motor drive allowable load value can be set to a minimum value that allows the motor 32 to continue to rotate at a duty ratio of 5%.

  Returning to the flowchart of FIG. 3, the ECU 200 closes the accumulator cut valve 54 in S110, opens the pressure increasing valve 40 by a predetermined amount, and detects whether the rotor of the motor 32 is currently rotating (S112). This detection can be detected based on information from, for example, a rotation angle sensor (not shown) disposed near the rotor. When the rotor is rotating (Y in S112) and there is no braking request by the driver's operation of the brake pedal 12 or a braking request from the vehicle running control side (N in S114), the ECU 200 is rotated with respect to the motor 32. Rotation continuation control is performed to continue the operation (S116). As described above, the motor 32 having an energization failure in one phase is difficult to rotate more smoothly than normal, but the load is reduced by opening the pressure increasing valve 40 to leak brake fluid. Since it is controlled to the allowable load value of the fail motor drive, it can be rotated. However, if the motor 32 is continuously rotated, heat may be generated in excess of a preset allowable value, so care must be taken not to do so. Heat generation exceeding the allowable value may cause further failure of the motor 32 itself, and may adversely affect the motor driver 58 and other peripheral devices. Therefore, in the rotation continuation control in the present embodiment, the motor 32 is driven at a duty ratio such that the brake fluid circulates in the liquid path via the pressure increasing valve 40 controlled to the allowable load value for driving the fail motor. FIG. 4B shows the relationship between the duty ratio when the motor is driven and the brake fluid discharge amount of the pump 34 driven by the motor 32. In FIG. 4B, A% is the duty ratio during the rotation continuation control, and can be set to 5%, for example. As described above, by driving the motor 32 in a low load state, it is possible to avoid the heat generation exceeding the allowable value and to realize the continuous rotation of the motor 32 without causing problems in other configurations.

  The ECU 200 ends this flow when the ignition switch is switched from ON to OFF during the rotation continuation control (Y in S118). In S104, when the energization failure is confirmed, the driver may be informed that there is a failure in the motor 32. When it is determined in S106 that the failure is only one phase, the failure safe mode is set. The driver may be notified of the transition. Further, since the motor 32 has failed when the ignition switch is turned off in S118, a message prompting prompt repairs may be provided to the driver.

  If the ignition switch is not turned off in S118 (N in S118), for example, the process returns to S102, and the fail-safe process is continued while confirming the necessity of continuing the rotation of the motor 32 and the fail state.

  In S114, when there is a braking request by the driver's operation of the brake pedal 12 or a braking request from the vehicle running control side (Y in S114), the ECU 200 performs a braking request control on the motor 32 (S120). In this case, the duty ratio of the motor 32 is set to, for example, B% shown in FIG. 4B so that the hydraulic pressure corresponding to the braking request can be generated. The value of B% changes according to the required braking force (target braking force). Further, the current value of the pressure increasing valve 40 is set to, for example, Ib shown in FIG. 4A so that the opening of the pressure increasing valve 40 can provide the wheel cylinder 20 with the hydraulic pressure corresponding to the braking request. Since one phase of the motor 32 is in an energized failure state, the output torque may be lower than in a state in which there is no energized failure. Therefore, the duty ratio B% set corresponding to the braking request is lower than that in the no failure state. You may need to set it higher. Therefore, it is desirable to prepare in advance a control map or the like indicating the relationship between the duty ratio and the braking request at the time of one-phase failure by a test or the like. In another example, a relational expression may be held to calculate a duty ratio with respect to a braking request.

  Incidentally, in the motor 32, when an energization failure occurs in one phase, a portion corresponding to that phase becomes a dead point where the theoretical advance angle becomes zero. Therefore, depending on the rotation state of the rotor when the energization failure occurs, the dead point may not be overcome and the rotation may stop. Further, when the energization failure occurs when the motor 32 stops rotating, the rotation cannot be started. Therefore, in the present embodiment, when the rotor of the motor 32 is stopped in S112 (N in S112), the overcoming torque generation control for urging the rotor to rotate again is executed (S122).

  Examples of overcoming torque generation control are shown in FIGS.

  The example shown in the flowchart of FIG. 5 repeats control of forward rotation and reverse rotation between the two phases that do not cause energization failure, and generates torque (inertial force) for overcoming the dead point by swinging the rotor. I am letting. In the overcoming torque generation control, first, a duty ratio sufficient to generate the overcoming torque is set (S200). In the case of the present embodiment, for example, when the average duty ratio at the time of braking request control in S120 is B% (for example, 20%), the duty ratio at the time of overcoming torque generation control by swinging is set to C% (for example, 40%). ) Is set. The ECU 200 performs forward / reverse switching by the motor driver 58 so that the current flows in the forward direction and the reverse direction in each phase 56 that does not cause an energization failure at this duty ratio (S202). Then, when a sufficient torque for overcoming the dead point can be generated by this swing (Y in S204), the ECU 200 performs control to flow current only in the forward direction via the motor driver 58 (S206), Re-rotate the rotor. If the overcoming torque has not been reached in S204 (N in S204), the process returns to S202, and the forward / reverse rotation control is continued repeatedly.

  In the example shown in the flowchart of FIG. 6, the duty ratio is increased to a value at which the torque is overcome in the preceding phase in the rotational direction with respect to the phase corresponding to the dead point. The ECU 200 can detect in which phase the current-carrying failure is currently occurring from the current value of each phase provided from the motor driver 58. Therefore, when the phase in which the current is to flow is not the previous phase in the rotational direction with respect to the phase corresponding to the dead point (N in S210), the ECU 200 under the pressure-increasing valve 40 controlled to the fail motor drive allowable load value. A duty ratio that can be rotated, for example, A% (for example, 5%) in FIG. 4B is set (S212). On the other hand, if the phase through which the current is to flow is the previous phase in the rotational direction with respect to the phase corresponding to the dead point (Y in S210), the torque (inertial force) that accelerates the rotation of the rotor and overcomes the dead point is increased. In order to generate it, the duty ratio is set to, for example, D% (for example, 10%) in FIG. 4B (S214). If the rotor has not rotated more than once (N in S216), the process returns to S210 and this flow is repeated. On the other hand, if the rotor has rotated one or more times (Y in S216), this flow ends.

  5 and FIG. 6 are controls for re-rotating the rotor when the motor 32 in which one phase is energized and failing is stopped, the configuration and control form of the motor 32 are the same. One of the controls is performed accordingly.

  Returning to the flowchart of FIG. 3, when the rotor of the motor 32 is re-rotated by the overcoming torque generation control in S122 and the rotation of the rotor can be continued (Y in S124), the process proceeds to S114 and the braking request is made. Control according to the presence or absence is started. Further, when the rotor is not continuously rotating, that is, when the rotation is stopped after one rotation even if the overcoming torque generation control is performed (N in S124), the overcoming torque generation control shown in FIGS. 5 and 6 is performed. Retry a predetermined number of times (for example, n times set in advance, for example, 5 times) (Y in S126). If the number of retries for overcoming torque generation control has reached n times (N in S126), that is, if the continuous rotation of the rotor is still not possible, the flow proceeds to S108, error processing is performed, and this flow is terminated.

  The value of the duty ratio C% and the duty ratio D% may be the same during the retry of the overcoming torque generation control n times, or the values of the duty ratio C% and the duty ratio D% are increased as the number of retries increases. May be. Increasing the value of the duty ratio increases the inertial force of the rotor, making it possible to achieve continuous rotation of the rotor more quickly.

  Thus, according to the brake control device 10 of the present embodiment, when the failure of the brushless motor is a single-phase energization failure, the rotation operation can be continued regardless of whether the brushless motor rotates during the failure. . As a result, even when a failure occurs in the brushless motor, the pump operation by driving the brushless motor can be continued, and the necessary hydraulic pressure and the braking force by the hydraulic pressure can be ensured. Moreover, since this fail safe can be realized only by the control of the brake control device 10, the brake control device 10 is not greatly increased in cost and size.

  In the rotation continuation control in S116 in the flowchart of FIG. 3, an example is shown in which the duty ratio is set to a low value (for example, A%). In the braking request control in S120, an example is shown in which the duty ratio is changed according to the value of the braking request. As an example of this application, the overcoming torque generation control as shown in the flowchart of FIG. If the motor 32 having an energization failure starts rotating, it can be continuously rotated by passing a current through a phase without the energization failure, but it may be stopped due to a dead point. Therefore, the overcoming torque generation control described with reference to FIG. 6 is also performed on the rotating motor 32. As a result, stable continuous rotation can be maintained without stopping even when there is a dead point.

  Further, in the present embodiment, after the energization failure occurs, the accumulator cut valve 54 is closed and the pressure increasing valve 40 is opened, and the motor 32 is continuously rotated to circulate the brake fluid even when there is no braking request. An example is shown. The accumulator cut valve 54 may not be provided. In another example, when the required amount of hydraulic pressure is secured in the accumulator 50 even after the energization failure occurs, the failed motor 32 is temporarily stopped, and the hydraulic pressure accumulated in the accumulator 50 at the time of a braking request. The braking force may be generated using Then, when pressure accumulation in the accumulator 50 becomes necessary due to consumption of hydraulic pressure, the overcoming torque generation control shown in FIGS. 5 and 6 may be executed to rotate the motor 32 again to accumulate pressure. In this case, it is desirable that the pressure accumulation target value of the accumulator 50 is set so that the load is not applied to the motor 32 as much as possible when it is lower than when there is no failure.

  In the present embodiment, the system including the accumulator 50 is shown. However, the present embodiment is also applied to a system in which the accumulator 50 is omitted and the motor 32 is rotated to supply the hydraulic pressure directly from the pump 34 to the pressure increasing valve 40. The same effect can be obtained.

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

It is a systematic diagram which shows the brake control apparatus which concerns on this embodiment centering on the hydraulic circuit. It is explanatory drawing explaining the schematic structure of the motor comprised with the brushless motor used by this embodiment, and relationship with ECU. It is a flowchart explaining the fail safe control at the time of the energization failure of the brushless motor in this embodiment. It is explanatory drawing explaining the control amount at the time of the energization failure of the brushless motor in this embodiment, (a) shows the relationship between the electric current value given to a pressure increase valve, and the opening degree or flow volume of a pressure increase valve, (b) is The relationship between the duty ratio when driving the motor and the discharge amount of the brake fluid of the pump by driving the motor is shown. It is a flowchart explaining the detail of the overcoming torque generation control at the time of the energization failure of the brushless motor in this embodiment. It is a flowchart explaining the detail of the other example of the overcoming torque generation control at the time of the energization failure of the three-phase brushless motor in this embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Brake control apparatus, 12 Brake pedal, 14 Master cylinder, 16, 18 Brake hydraulic pressure control pipe, 20 Wheel cylinder, 26 Reservoir tank, 28 Hydraulic supply / discharge pipe, 30 High pressure pipe, 32 Motor, 34 Pump, 40 Booster valve , 42 pressure reducing valve, 44 cylinder pressure sensor, 46 stroke sensor, 50 accumulator, 53 relief valve, 54 accumulator cut valve, 56 phase, 58 motor driver, 60 power supply, 80 hydraulic actuator, 200 ECU.

Claims (5)

A brake control device that discharges hydraulic fluid by a pump driven by a brushless motor and supplies the hydraulic pressure of the hydraulic fluid to a wheel cylinder to generate a braking force,
A fail detection means for detecting an energization failure to the brushless motor;
A pressure reduction control means for reducing the hydraulic pressure on the discharge side of the pump to a fail motor drive allowable load value and continuing to drive the brushless motor when the fail detection means detects an energization failure;
A brake control device comprising:   2. A torque adjusting means for adjusting a rotational torque so that the brushless motor rotates under a load under the fail motor drive allowable load value when the fail detecting means detects an energization failure. The brake control device described.   3. The torque adjustment unit according to claim 2, wherein the torque adjustment means adjusts the torque so as to generate a passing-over torque that rotates by overcoming a dead point at which a theoretical advance angle of the rotor of the brushless motor becomes zero by an inertial force of the rotor. The brake control device described.   4. The brake control device according to claim 3, wherein the torque adjusting means increases the duty ratio to a value at which the overcoming torque is generated in a front phase in a rotational direction with respect to a phase corresponding to the dead point.   4. The brake control device according to claim 3, wherein the torque adjusting means controls the phase other than the phase corresponding to the dead point to cause the rotor to rotate forward and reverse to generate the overcoming torque.

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