JP4953832B2 - Brake device - Google Patents

Description

  The present invention includes a brake fluid pressure generating means for generating a brake fluid pressure by driving a piston fitted in a cylinder so as to be movable back and forth in an axial direction from an initial position by an actuator in an axial direction, and operating with the brake fluid pressure. The present invention relates to a brake device including a wheel cylinder that generates a braking force for braking a wheel.

A so-called BBW (brake-by-wire) that converts a driver's braking operation into an electric signal, operates an electric hydraulic pressure generating means (slave cylinder), and operates a wheel cylinder with a brake hydraulic pressure generated by the slave cylinder. ) Type brake device is known from US Pat.
Japanese Patent No. 3205570

  By the way, the electric hydraulic pressure generating means (slave cylinder) of such a BBW type brake device generates a brake hydraulic pressure by driving a piston that is slidably fitted into the cylinder by an electric motor. There is a loss stroke of the piston from when the piston starts moving forward by the motor to when the brake fluid pressure is generated in the cylinder, and there is a problem that the response of generating the braking force is lowered.

  The loss stroke occurs, for example, for the following reason. In the side port type slave cylinder, the brake fluid pressure is generated in the cylinder at the moment when the cup seal provided on the piston passes through the relief port connected to the reservoir, but the piston moves forward from the initial position where it stops before starting braking. The brake fluid pressure is not generated until the cup seal that has started passing through the relief port, and the advance distance of the piston during that time becomes the loss stroke.

  In a center port type slave cylinder in which a valve is arranged in a through-hole penetrating the center of the piston back and forth, the brake fluid pressure is generated in the cylinder at the moment when the piston starts to advance from the initial position and the valve is closed. However, no brake hydraulic pressure is generated until the valve is closed after the piston starts moving forward, and the forward moving distance of the piston in the meantime becomes the loss stroke.

  In order to minimize the loss stroke and improve the response to the generation of braking force, the initial position of the piston is precisely controlled. As soon as the piston starts moving forward, the cup seal passes through the relief port, or the piston As soon as the valve starts moving from the initial position, it is necessary to close the valve. Therefore, conventionally, it has been necessary to perform troublesome control in which the piston once retracted to the reverse limit after the end of braking is advanced by an electric motor and stopped at an appropriate initial position.

  The present invention has been made in view of the above circumstances, and an object thereof is to minimize the loss stroke of the piston while making it possible to easily adjust the initial position of the piston of the brake fluid pressure generating means.

In order to achieve the above object, according to the first aspect of the present invention, a master cylinder that generates a brake fluid pressure in accordance with an operation amount of a brake pedal, and connected to the master cylinder, is axially connected to the cylinder. A brake fluid pressure generating means for generating a brake fluid pressure by driving a piston to be fitted back and forth forward from an initial position in an axial direction by an actuator, and a braking force for operating the brake fluid pressure to brake a wheel. a brake device equipped with the wheel cylinder, said brake fluid pressure generating means, Rutotomoni an adjustment member for adjusting the initial position of the piston, wherein the actuator comprises an output shaft for driving forward to press the piston, The adjusting member is a screw member that is provided in the actuator housing so as to be movable back and forth in the axial direction and is in contact with the rear end of the output shaft. Brake device is proposed which is characterized in that it is provided to be operated from the outside of the actuator housing.

The cylinder body 36 of the embodiment corresponds to the cylinder of the present invention, the slave cylinder 23 of the embodiment corresponds to the brake fluid pressure generating means of the present invention, and the screw member 63 of the embodiment corresponds to the present invention. Corresponds to the adjustment member.

According to the first aspect of the present invention , the brake fluid pressure generating means is connected to the master cylinder that generates the brake fluid pressure according to the operation amount of the brake pedal, and the actuator of the brake fluid pressure generating means can be moved forward and backward. When the piston to be fitted is driven forward in the axial direction from the initial position, the wheel cylinder is actuated by the brake fluid pressure generated in the cylinder to brake the wheel. Since the brake fluid pressure generating means includes an adjustment member that adjusts the initial position of the piston in the axial direction, the piston starts to move forward without adjusting the initial position by controlling the actuator each time the piston is operated. It is possible to improve the responsiveness of generating the braking force by minimizing the loss stroke from when the brake fluid pressure is generated. In particular, the adjustment member that adjusts the initial position of the piston in the axial direction is configured by a screw member that is provided in the actuator housing so as to be movable back and forth in the axial direction and abuts on the rear end of the output shaft. The initial position in the axial direction of the piston can be adjusted by regulating the retracted end of the output shaft by rotating the screw member from the outside of the actuator housing in a stage.

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

1 to 3 show a implementation of the present invention, FIG. 1 is a hydraulic circuit diagram of a normal brake system, Figure 2 is a hydraulic circuit diagram at the time of abnormality corresponding to FIG. 1, FIG. 3 is an enlarged view of part 3 of FIG.

  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. A slave cylinder 23 is arranged between Pc and Qc, and an ABS device 24 is arranged 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. .

  As shown in FIG. 3, the actuator 51 of the slave cylinder 23 includes a drive bevel gear 53 provided on the rotating shaft of the electric motor 52, a driven bevel gear 54 that meshes with the drive bevel gear 53, and a ball screw mechanism 55 that is operated by the driven bevel gear 54. With. A sleeve 58 is rotatably supported on the actuator housing 56 via a pair of ball bearings 57, 57. An output shaft 59 is coaxially disposed on the inner periphery of the sleeve 58, and a driven bevel gear 54 is provided on the outer periphery thereof. Fixed.

  The ball screw mechanism 55 includes a female screw 60 formed on the inner periphery of the sleeve 58, a male screw 61 formed on the outer periphery of the output shaft 59, and a plurality of balls 62 disposed between the female screw 60 and the male screw 61. A screw member 63 as an adjustment member is screwed into the actuator housing 56, and the front end of the screw member 63 contacts the rear end of the output shaft 59.

  A pair of pistons 38A and 38B urged in a backward direction by a pair of return springs 37A and 37B are slidably disposed in the cylinder main body 36 of the slave cylinder 23, and a pair of pistons 38A and 38B are disposed on the front surfaces of the pistons 38A and 38B. The second hydraulic chambers 39A and 39B are partitioned. The front end of the output shaft 59 contacts the rear end of the rear piston 38A. 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.

  Thus, when the electric motor 52 is driven in one direction, the output shaft 59 moves forward via the drive bevel gear 53, the driven bevel gear 54, and the ball screw mechanism 55. As a result, the pair of pistons 38A and 38B pressed by the output shaft 59 moves forward, and the brake fluid pressure is applied to the second fluid pressure chambers 39A and 39B at the moment when the ports 40A and 40B connected to the fluid paths Pb and Qb are closed. The brake fluid pressure can be generated and output to the fluid passages Pc and Qc via the ports 41A and 41B.

  Returning to FIG. 1, the structure of the ABS device 24 is well known, and includes a system of disc brake devices 14 and 15 for the left front wheel and the right rear wheel, and a system of disc brake devices 18 and 19 for the right front wheel and the left rear wheel. The same structure is 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.

  An electronic control unit (not shown) that controls the operation of the shutoff valves 22A and 22B, the reaction force permission valve 25, the slave cylinder 23, and the ABS device 24 includes a hydraulic pressure sensor Sa that detects the brake hydraulic pressure generated by the master cylinder 11. The hydraulic pressure sensor Sb for detecting the brake hydraulic pressure transmitted to the disc brake devices 18 and 19 and the wheel speed sensor Sc for detecting the wheel speed of each wheel are connected.

  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 fluid path Qa detects that the driver depresses the brake pedal 12, the actuator 51 of the slave cylinder 23 is operated 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 slave cylinder 23 are slightly advanced, the ports 40A and 40B are closed and the communication between the fluid passages Pb and Qb and the second fluid 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.

  The brake fluid pressure detected by the slave cylinder 23 detected by the fluid pressure sensor Sb provided in the fluid passage Qc becomes a magnitude corresponding to the brake fluid pressure detected 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 51 of the slave cylinder 23, it is possible to cause the disc brake devices 14, 15, 18, and 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 slave cylinder 23 is maintained in the operating state. In this state, the ABS device 24 is operated 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 slave 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.

  When the slave 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 slave cylinder 23.

  That is, when the power supply fails, as shown in FIG. 2, the shutoff valves 22A and 22B made of normally open solenoid valves are automatically opened, and the reaction force permission valve 25 made of normally closed solenoid valves is automatically turned on. The in-valve 42 made up of a normally open type electromagnetic valve is automatically opened, and the out valve 44 made up of a normally closed type 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 slave 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.

  When the electric motor 52 of the actuator 51 of the slave cylinder 23 rotates in one direction, the output shaft 59 moves forward, and the cup seals 65A and 65B of the pistons 38A and 38B pushed by the output shaft 59 become ports (relief ports) 40A, The brake fluid pressure is generated in the second fluid pressure chambers 39A and 39B at the moment when 40B (see FIG. 3) is passed from the rear to the front, and the wheel cylinders 16, 17, 20, and 21 generate the braking force.

  When the electric motor 52 rotates in the reverse direction after braking, the output shaft 59 moves backward, and the pistons 38A and 38B move backward accordingly. At this time, if the pistons 38A and 38B stop at the moment when their cup seals 65A and 65B pass through the relief ports 40A and 40B from the front to the rear, the loss stroke when the pistons 38A and 38B advance next time is minimized. And the responsiveness of generating braking force can be improved. In order to stop the cup seals 65A and 65B of the pistons 38A and 38B at the moment when the relief ports 40A and 40B pass from the front to the rear, the output of the screw member 63 screwed into the actuator housing 56 is adjusted by adjusting the amount of protrusion. The backward end of the shaft 59 may be regulated.

  As described above, according to the present embodiment, once the assembly of the slave cylinder 36 is completed, the protruding amount of the screw member 63 is only adjusted once, and thereafter the pistons 38A and 38B are stopped each time the brake operation is performed. The loss stroke of the pistons 38A and 38B can be minimized without electrically controlling the position.

Next, a reference example of the present invention will be described with reference to FIG.

Although the implementation of the embodiment has a screw member 63 provided in the actuator housing 56, reference example to the front end of the output shaft 59, it is provided with a contact capable of threaded member 64 to the rear end of the piston 38A. The retracted end of the output shaft 59 is regulated by the rear end thereof coming into contact with the inner surface of the actuator housing 56.

  Accordingly, when the rear end of the output shaft 59 comes into contact with the inner surface of the actuator housing 56 and stops, the screw member 64 so that the cup seals 65A and 65B of the pistons 38A and 38B are positioned immediately after the relief ports 40A and 40B. Is adjusted, the loss stroke of the pistons 38A and 38B can be minimized without electrically controlling the stop positions of the pistons 38A and 38B every time the brake operation is performed.

  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 ball screw mechanism 55 is used for the actuator 51 that moves the output shaft 59 back and forth, but the structure of the actuator 51 is arbitrary.

Hydraulic circuit diagram of a normal brake system according to the form of implementation Hydraulic circuit diagram at the time of abnormality corresponding to FIG. 3 enlarged view of FIG. The figure corresponding to the above-mentioned Drawing 3 concerning a reference example

11 master cylinder
12 brake pedal 16 wheel cylinder 17 wheel cylinder 20 wheel cylinder 21 wheel cylinder 23 slave cylinder (brake fluid pressure generating means)
36 Cylinder body (cylinder)
38A Piston 38B Piston 51 Actuator 56 Actuator housing 59 Output shaft 63 Screw member (adjustment member )

Claims (1)

A master cylinder (11) that generates brake fluid pressure in accordance with the amount of operation of the brake pedal (12);
Pistons (38A, 38B), which are connected to the master cylinder (11) and are fitted to the cylinder (36) so as to be able to advance and retreat in the axial direction, are driven forward from the initial position in the axial direction by the actuator (51) to increase the brake fluid pressure. Generating brake fluid pressure generating means (23);
A wheel cylinder (16, 17, 20, 21) that generates a braking force for operating the brake fluid pressure to brake the wheel;
In a brake device comprising:
Said brake fluid pressure generating means (23), the piston (38A, 38B) Rutotomoni includes an initial position adjusting an adjustment member (6 3) of said actuator (51) presses the piston (38A, 38B) The adjusting member (63) is a screw member that is provided in the actuator housing (56) so as to be movable forward and backward in the axial direction and abuts against the rear end of the output shaft (59). The brake device is provided so as to be operable from the outside of the actuator housing (56) .

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