JP2009166578A - Braking device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a response that a motor cylinder operated by an electric motor 32 generates a brake fluid pressure when an own vehicle may possibly collide with an obstacle. <P>SOLUTION: A collision damage reducing control electronic control unit Ub determines the urgency of braking based on the state of an external world detected by an external world sensing means Sd which includes a radar device or a television camera, and executes a field control or a lead angle control by weakening an electric motor 32 of the motor cylinder according to the level of the determined urgency. This constitution can enhance the rotating speed of the electric motor 32 in the urgency and quickly generate the brake fluid pressure to a motor cylinder to improve the response of the braking. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a brake device provided with an electric hydraulic pressure generating means that electrically generates a brake hydraulic pressure with a driving force of an electric motor in accordance with an operation amount or an operating force of a brake operator operated by a driver. .

  A so-called BBW (brake-by-wire) brake device that converts a driver's braking operation into an electric signal to operate a motor cylinder and operates a wheel cylinder with the brake fluid pressure generated by the motor cylinder is disclosed in the following patent It is known from document 1.

The BBW brake device includes a master cylinder that operates by a brake pedal to generate brake fluid pressure, a motor cylinder that operates by an electric motor to generate brake fluid pressure, and a wheel cylinder that brakes wheels. When the motor cylinder can operate normally, braking is performed by operating the wheel cylinder with the brake fluid pressure generated by the motor cylinder according to the amount of operation of the brake pedal, and when the motor cylinder cannot operate, the master cylinder generates the brake Braking is performed by operating the wheel cylinder with hydraulic pressure.
JP 2007-245823 A

  By the way, since the operation speed of the electric motor of a motor cylinder is constant, what was described in the said patent document 1 is brake fluid pressure to a motor cylinder by the command from collision damage reduction control ECU which avoids the collision with other vehicles. Even if it is going to generate | occur | produce, since an electric motor does not respond quickly, time lag will arise before a wheel cylinder generate | occur | produces braking force, and collision damage mitigation control may not be able to exhibit sufficient effect.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to increase the responsiveness of the electrical hydraulic pressure generating means to generate the brake hydraulic pressure when the vehicle may collide with an obstacle. To do.

  In order to achieve the above object, according to the first aspect of the present invention, the brake fluid is electrically driven by the driving force of the electric motor in accordance with the operation amount or operation force of the brake operator operated by the driver. In a brake device having an electric hydraulic pressure generating means for generating pressure, the emergency of braking is determined from the external situation detected by the external sensing means, and the electric motor is weakened according to the determined emergency level. Alternatively, there is proposed a brake device including control means for controlling the advance angle.

  The brake pedal 12 of the embodiment corresponds to the brake operator of the present invention, the motor cylinder 23 of the embodiment corresponds to the electric hydraulic pressure generating means of the present invention, and the brake control electronic control unit of the embodiment. Ua and collision damage reduction control electronic control unit Ub correspond to the control means of the present invention.

  According to the configuration of the first aspect, the control means determines the urgency of braking based on the external situation detected by the external sensing means, and the electrical hydraulic pressure generating means determines the urgency of the braking according to the determined urgency. Since the electric motor is subjected to field weakening control or advance angle control, it is possible to increase the rotational speed of the electric motor in an emergency and to quickly generate the brake hydraulic pressure in the electric hydraulic pressure generating means, thereby improving the responsiveness of braking.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  1 to 3 show an embodiment of the present invention. FIG. 1 is a hydraulic circuit diagram of a vehicle brake device in a normal state, and FIG. 2 is a hydraulic circuit diagram in an abnormal state corresponding to FIG. 3 is a block diagram of the control system.

  As shown in FIG. 1, the tandem master cylinder 11 includes two first hydraulic pressure chambers 13A and 13B that output brake hydraulic pressure in accordance with the pedaling force of the driver stepping on the brake pedal 12. The first hydraulic chamber 13A is connected to the wheel cylinders 16 and 17 of the disc brake devices 14 and 15 of the left front wheel and the right rear wheel, for example, via the fluid paths Pa, Pb, Pc, Pd, and Pe. The one hydraulic chamber 13B is connected to the wheel cylinders 20 and 21 of the disc brake devices 18 and 19 of the right front wheel and the left rear wheel, for example, via the fluid paths Qa, Qb, Qc, Qd, and Qe.

  A shutoff valve 22A, which is a normally open solenoid valve, is disposed between the fluid paths Pa, Pb, and a shutoff valve 22B, which is a normally open solenoid valve, is disposed between the fluid paths Qa, Qb, and the fluid paths Pb, Qb and the fluid path. The motor cylinder 23 is disposed between Pc and Qc, and the ABS device 24 is disposed between the liquid paths Pc and Qc and the liquid paths Pd and Pe; Qd and Qe.

  A stroke simulator 26 is connected to the liquid paths Ra and Rb branched from the liquid path Qa via a reaction force permission valve 25 which is a normally closed solenoid valve. The stroke simulator 26 is a cylinder 27 in which a piston 29 urged by a spring 28 is slidably fitted, and a liquid chamber 30 formed on the side opposite to the spring 28 of the piston 29 communicates with a liquid path Rb. .

  The actuator 31 of the motor cylinder 23 includes a drive bevel gear 33 provided on the output shaft of the electric motor 32, a driven bevel gear 34 that meshes with the drive bevel gear 33, and a ball screw mechanism 35 that is operated by the driven bevel gear 34. A pair of pistons 38A, 38B urged in a backward direction by a pair of return springs 37A, 37B are slidably disposed inside the cylinder body 36 of the motor cylinder 23, and a pair of pistons 38A, 38B are placed on the front surfaces of the pistons 38A, 38B. The second hydraulic chambers 39A and 39B are partitioned. One second hydraulic chamber 39A communicates with fluid paths Pb and Pc via ports 40A and 41A, and the other second hydraulic chamber 39B communicates with fluid paths Qb and Qc via ports 40B and 41B.

  When the electric motor 32 is driven in one direction, the pair of pistons 38A and 38B move forward via the drive bevel gear 33, the driven bevel gear 34, and the ball screw mechanism 35, and the ports 40A and 40B connected to the liquid passages Pb and Qb are provided. The brake fluid pressure can be generated in the second fluid pressure chambers 39A and 39B at the moment of closing, and the brake fluid pressure can be output to the fluid passages Pc and Qc via the ports 41A and 41B.

  The structure of the ABS device 24 is well known, and the system of the left front wheel and right rear wheel disc brake devices 14 and 15 and the system of the right front wheel and left rear wheel disc brake devices 18 and 19 have the same structure. Provided. As a representative example, the system of the disc brake devices 14 and 15 for the left front wheel and the right rear wheel will be described. Between the liquid passage Pc and the liquid passages Pd and Pe, in-valves 42 and 42 made up of a pair of normally open solenoid valves are arranged. In addition, out valves 44 and 44, which are normally closed electromagnetic valves, are disposed between the fluid paths Pd and Pe on the downstream side of the in valves 42 and 42 and the reservoir 43. A hydraulic pump 47 sandwiched between a pair of check valves 45 and 46 is disposed between the reservoir 43 and the fluid path Pc. The hydraulic pump 47 is driven by an electric motor 48.

  As shown in FIG. 3, the brake control electronic control unit Ua includes a hydraulic pressure sensor Sa that detects the brake hydraulic pressure generated by the master cylinder 11 and a hydraulic pressure that detects the brake hydraulic pressure transmitted to the disc brake devices 18 and 19. Based on the signals from the pressure sensor Sb and the wheel speed sensors Sc that detect the wheel speed of each wheel, the operation of the shutoff valves 22A and 22B, the reaction force permission valve 25, the motor cylinder 23 and the ABS device 24 is controlled. . The collision damage mitigation control electronic control unit Ub connected to the brake control electronic control unit Ua by CAN communication is based on a signal from an external sensing means Sd made of, for example, a radar device or a TV camera, While calculating the high possibility of collision with an object, the response level of the motor cylinder 23 corresponding to the high possibility is transmitted to the brake control electronic control unit Ua by CAN communication.

  Next, the operation of the embodiment of the present invention having the above configuration will be described.

  When the system functions normally, the shutoff valves 22A and 22B made of normally open solenoid valves are demagnetized and opened, and the reaction force permission valve 25 made of normally closed solenoid valves is excited and opened. In this state, when the hydraulic pressure sensor Sa provided in the liquid path Qa detects the depression of the brake pedal 12 by the driver, the actuator 31 of the motor cylinder 23 is actuated to advance the pair of pistons 38A and 38B. Brake hydraulic pressure is generated in the second hydraulic pressure chambers 39A and 39B. The brake fluid pressure is transmitted to the wheel cylinders 16, 17, 20, and 21 of the disc brake devices 14, 15, 18, and 19 via the in-valves 42 that are opened by the ABS device 24, and brakes each wheel.

  When the pistons 38A and 38B of the motor cylinder 23 are slightly advanced, the ports 40A and 40B are closed, and the communication between the liquid passages Pb and Qb and the second hydraulic pressure chambers 39A and 39B is cut off, so that the master cylinder 11 is generated. The brake fluid pressure thus transmitted is not transmitted to the disc brake devices 14, 15, 18, and 19. At this time, the brake fluid pressure generated in the other first fluid pressure chamber 13B of the master cylinder 11 is transmitted to the fluid chamber 30 of the stroke simulator 26 through the opened reaction force permission valve 25, and the piston 29 is transmitted to the spring 28. By moving the brake pedal against this, it is possible to allow the stroke of the brake pedal 12 and generate a pseudo pedal reaction force to eliminate the driver's uncomfortable feeling.

  Then, the brake fluid pressure by the motor cylinder 23 detected by the fluid pressure sensor Sb provided in the fluid passage Qc has a magnitude corresponding to the brake fluid pressure by the master cylinder 11 detected by the fluid pressure sensor Sa provided in the fluid passage Qa. As described above, by controlling the operation of the actuator 31 of the motor cylinder 23, it is possible to cause the disc brake devices 14, 15, 18, 19 to generate a braking force corresponding to the pedaling force input to the brake pedal 12 by the driver.

  During the braking described above, when it is detected that the slip ratio of any wheel has increased due to the output of the wheel speed sensor Sc..., The shutoff valve 22A comprising a normally open solenoid valve is detected. 22B is excited to close the valve and the motor cylinder 23 is maintained in the operating state, and the ABS device 24 is operated in this state to prevent the wheels from being locked.

  That is, when a predetermined wheel tends to be locked, the in-valve 42 connected to the wheel cylinder of the disc brake device of the wheel is closed and the out-valve 44 is opened with the transmission of the brake fluid pressure from the motor cylinder 23 blocked. The wheel does not lock by performing a pressure reducing action to release the brake fluid pressure of the wheel cylinder to the reservoir 43 and a holding action to close the out valve 44 and hold the brake fluid pressure of the wheel cylinder. So as to reduce the braking force.

  As a result, when the wheel speed recovers and the slip ratio decreases, the braking force of the wheel is increased by opening the in-valve 42 and increasing the brake fluid pressure of the wheel cylinder. When the wheel becomes locked again by this pressure increasing action, the pressure reduction, holding, and pressure increasing are executed again, and the maximum braking force can be generated while suppressing the wheel lock by repeating the operation. In the meantime, the brake fluid that has flowed into the reservoir 43 is returned to the upstream fluid paths Pc and Qc by the hydraulic pump 47.

  While the above-described ABS control is executed, the shutoff valves 22A and 22B are maintained in the closed state, so that the hydraulic pressure change due to the operation of the ABS device 24 becomes a kickback, and the master cylinder 11 transfers to the brake pedal 12. It can be prevented from being transmitted.

  Since the ABS device 24 has a function of individually controlling the braking force of the four wheels, by using this ABS device 24 to control the yaw moment by the right and left distribution of the braking force, the turning performance of the vehicle and the straight traveling Stability performance can be improved. That is, the braking force of the inner turning wheel can be made larger than the braking force of the outer turning wheel to improve the turning performance, or the braking force of the turning outer wheel can be made larger than the braking force of the turning inner wheel to improve the straight running stability performance. . When the yaw moment is controlled by the right / left distribution of the braking force, when the brake pedal 12 is depressed, the shutoff valves 22A and 22B are closed to suppress kickback due to the operation of the ABS device 24. Is done. When the brake pedal 12 is not depressed, the problem of kickback does not occur, so that the shutoff valves 22A and 22B are maintained in the open state.

  When the motor cylinder 23 becomes inoperable due to a power failure or the like, braking is performed by the brake fluid pressure generated by the master cylinder 11 instead of the brake fluid pressure generated by the motor cylinder 23.

  When the power supply fails, as shown in FIG. 2, the shut-off valves 22A and 22B composed of normally open solenoid valves are automatically closed, and the reaction force permission valve 25 composed of normally closed solenoid valves is automatically closed. The in-valve 42 made up of a normally-open electromagnetic valve is automatically opened, and the out-valve 44 made up of a normally-closed electromagnetic valve is automatically closed. In this state, the brake hydraulic pressure generated in the first hydraulic chambers 13A and 13B of the master cylinder 11 is not absorbed by the stroke simulator 26, and the shutoff valves 22A and 22B and the second hydraulic chamber 39A of the motor cylinder 23 are absorbed. , 39B and the in-valve 42..., The wheel cylinders 16, 17, 20, 21 of the disc brake devices 14, 15, 18, 19 of each wheel can be operated to generate a braking force without any trouble.

  At the time of the abnormality described above, the fluid path Pa, the shutoff valve 22A, the fluid path Pb, the one second fluid pressure chamber 39A of the motor cylinder 23, the fluid path Pc, and the fluid path from one first fluid pressure chamber 13A of the master cylinder 11 A first hydraulic system connected to the wheel cylinders 16 and 17 of the disc brake devices 14 and 15 for the left front wheel and the right rear wheel via Pd and Pe, and a fluid path from the other first hydraulic chamber 13B of the master cylinder 11 Wheels of the disc brake devices 18 and 19 for the right front wheel and the left rear wheel via Qa, the shutoff valve 22B, the fluid passage Qb, the other second fluid pressure chamber 39B of the motor cylinder 23, the fluid passage Qc and the fluid passages Qd and Qe Since the second hydraulic system connected to the cylinders 20 and 21 is completely separated and independent, troubles such as leakage of the brake hydraulic pressure or blockage of the fluid path in one of the first and second hydraulic systems. Occurs Also, it is possible to allow for fail-safe by generating a braking force to at least two wheels of a four-wheel.

  In the above description, the motor cylinder 23 operates according to the operation of the brake pedal 12 by the driver. However, depending on the high possibility of collision with the obstacle calculated by the collision damage reduction control electronic control unit Ub, Regardless of whether or not the pedal 12 is operated, the brake control electronic control unit Ua may actuate the motor cylinder 23 to generate a braking force.

  That is, when the collision damage reduction control electronic control unit Ub determines that the collision possibility is low according to the predicted time until the collision, the low response command is determined to be moderate. In this case, the medium response command is transmitted to the brake control electronic control unit Ua when it is determined that the possibility of collision is high. The brake control electronic control unit Ua weakens the electric motor 32 according to the response speed command value and controls the magnetic flux to increase the rotation speed, so that the rear piston 38A and the front piston 38B are compared with the case where there is no possibility of collision. It is possible to increase the responsiveness that the braking force is generated by increasing the moving speed. Specifically, the higher the possibility of collision, the higher the response speed command value. As the response speed command value increases, the field-weakening control is strengthened in three stages: low, medium and high. Control is performed so that the responsiveness of generating braking force is increased by increasing the rotational speed of the motor 32 in three stages.

  The field weakening control of the electric motor 32 is performed when current feedback control is performed so that the actual current supplied to the electric motor 32 matches the target current. When the electric motor 32 is voltage controlled, the field weakening control is performed. Leading angle control is used.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, in the embodiment, the collision damage reduction control electronic control unit Ub transmits low response, medium response, and high response commands of the electric motor 32 to the brake control electronic control unit Ua, but field weakening control (or advance angle control) ) May be transmitted to the brake control electronic control unit Ua, and the command value of the field weakening amount (or advance amount) of the electric motor 32 may be directly transmitted to the brake control electronic control unit Ua. May be communicated.

  In the embodiment, braking is performed by the brake fluid pressure generated by the motor cylinder 23 operated by the electric motor 32. However, braking is performed by directly driving a brake pad or the like with the driving force of the electric motor 32. Can do.

Hydraulic circuit diagram for a normal brake system for vehicles Hydraulic circuit diagram at the time of abnormality corresponding to FIG. Block diagram of control system

Explanation of symbols

12 Brake pedal (brake operator)
23 Motor cylinder (electrical fluid pressure generating means)
32 Electric motor Sd External sensing means Ua Brake control electronic control unit U (control means)
Ub Collision damage reduction control electronic control unit (control means)

Claims (1)

An electric hydraulic pressure generating means (23) that electrically generates a brake hydraulic pressure with a driving force of the electric motor (32) according to an operation amount or an operating force of the brake operating element (12) operated by the driver. In the brake device provided,
Control means (Ua, Ub) that determines braking urgency from the external environment detected by the external sensing means (Sd), and weakens the field control or advance angle control of the electric motor (32) according to the determined magnitude of urgency. ).

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