JP4801817B2 - Brake device - Google Patents

Description

  The present invention relates to a brake device provided with both a disc brake device and a drum brake device on one wheel.

A brake hydraulic pressure control device consisting of a hydraulic pump, reservoir, in-valve, out-valve, etc. is arranged between the master cylinder that is activated by the driver's operation of the brake pedal and the wheel cylinder provided on each wheel. The brake fluid pressure control device individually controls the brake fluid pressure that is transmitted to the wheel cylinder of each wheel while braking with the brake fluid pressure of the ABS. System) function and VAS (Vehicle Stability Assist) function that controls the yaw moment of the vehicle by giving a braking force difference between the left and right wheels with the brake fluid pressure generated by the brake fluid pressure control device Is known from Patent Document 1 below.
Japanese Patent Laid-Open No. 2005-178459

  By the way, in the above conventional one, the normal braking by the brake hydraulic pressure generated by the master cylinder and the braking for the VSA for controlling the yaw moment of the vehicle are generated by the operation of the wheel cylinder of the same disc brake device. When the temperature of the disc brake device rises due to the heat generated by the normal braking, there is a problem that it is difficult to accurately control the braking force for the VSA with the brake fluid pressure generated by the brake fluid pressure control device.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to accurately control the braking force of a wheel while suppressing the influence of heat generated by braking.

In order to achieve the above object, according to the invention described in claim 1, a disc brake device and a drum brake device are provided on each of at least a pair of left and right wheels ,
Of the disc brake device and the drum brake device, the disc brake device is operated with a brake hydraulic pressure generated by a master cylinder that is operated by a driver's brake operation, while the drum brake device is an electrically operated slave cylinder. there a brake system Ru is operated by the brake fluid pressure generated, wherein the disc brake device, said one of the wheels in the case of performing yaw moment control which imparts one braking force to the pair of right and left wheels when the vehicle is traveling A hydraulic pump capable of supplying a brake hydraulic pressure is connected to the disc brake device, and the slave cylinder is electrically operated during the yaw moment control, and brake fluid is supplied to the drum brake device of the one wheel. brake and wherein the supplying pressure Ru been proposed.

According to the present invention , among the disc brake device and the drum brake device respectively provided on the pair of left and right wheels, the disc brake device is operated with a brake hydraulic pressure generated by a master cylinder that is operated by a driver's brake operation , the drum brake device, since the electrically actuated slave cylinder is operated at a brake fluid pressure generated can be controlled in a variety of sizes of the braking force by actuating both or one of the two brake devices, for example, , if insufficient only braking force by the disc brake device, by electrically actuating the slave cylinder, Ru can generate an auxiliary braking force to the drum brake device. Even if the disc brake device operates with the brake fluid pressure generated by the master cylinder and generates heat, the drum brake device is not affected by the heat generation, so the braking force is accurately controlled with the brake fluid pressure generated by the slave cylinder. can do.

In particular, among the disc brake device and the drum brake device, the drum brake device is operated with the brake fluid pressure generated by the electrically operated slave cylinder, so that the pad clearance of the brake pad of the disc brake device is set to be large. Even when the responsiveness of the disc brake device decreases due to the prevention of rubbing, high response is ensured by operating the drum brake device that operates with the brake fluid pressure generated by the slave cylinder in advance of the disc brake device. can do.

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

  1 and 2 show an embodiment of the present invention. FIG. 1 is a hydraulic circuit diagram of a vehicle brake device, and FIG. 2 is a diagram showing a structure of a slave cylinder.

  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, for example, the wheel cylinders 16 and 17 of the disc brake devices 14 and 15 on the left and right front wheels via the fluid paths Pa, Pd, and Pe, and the other first hydraulic chamber 13B is liquid. For example, the left and right rear wheel disc brake devices 18, 19 are connected to the wheel cylinders 20, 21 via the roads Qa, Qd, Qe.

  The brake fluid pressure control device 24 disposed between the fluid paths Pa, Qa and the fluid paths Pd, Pe; Qd, Qe suppresses the slip of each wheel and shortens the stopping distance during braking (BS It has an anti-lock braking system) function and a VSA (vehicle stability assist) function for enhancing the steering stability of the vehicle by generating a difference in braking force between the left and right wheels. The brake fluid pressure control device 24 is provided with the same structure in the system of the disc brake devices 14 and 15 for the left and right front wheels and the system of the disc brake devices 18 and 19 for the left and right rear wheels.

  Hereinafter, the system of the disc brake devices 18 and 19 for the left and right rear wheels will be described as a representative example. In-valves 42 and 42 including a pair of normally-open electromagnetic valves are disposed between the liquid path Qa and the liquid paths Qd and Qe. In addition, out valves 44, 44 each including a pair of normally closed electromagnetic valves are disposed between the liquid passages Qd, Qe downstream of the in valves 42, 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 liquid path Qa. The hydraulic pump 47 is driven by an electric motor 48.

  Further, a regulator valve 61 composed of a normally-open electromagnetic valve capable of arbitrarily controlling the opening degree is disposed at a position before the liquid path Qa branches to the liquid paths Qd and Qe. In addition, a check valve 62 is arranged in series with the check valve 45, and a liquid path Qf branched from the check valve 45 and the check valve 62 is connected to the liquid path Qa on the upstream side of the regulator valve 61. A suction valve 63 comprising a normally closed electromagnetic valve is arranged.

  The left and right rear wheels are provided with drum brake devices 71 and 72 in addition to the disc brake devices 18 and 19. The wheel cylinders 73 and 74 of the drum brake devices 71 and 72 are braked from the slave cylinder 23. Hydraulic pressure is supplied.

  As apparent from FIG. 2, 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 meshing with the drive bevel gear 53, and a ball screw mechanism operated by the driven bevel gear 54. 55. 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.

  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. The reservoir 75 communicates with the wheel cylinder 73 via the liquid path Ra, the port 40A, one second hydraulic chamber 39A, the port 41A and the liquid paths Rb, Rc, and the reservoir 75 communicates with the liquid path Rd, the port 40B, the other The wheel cylinder 74 communicates with the second hydraulic chamber 39B, the port 41B, and the fluid passages Re and Rf.

  Further, an on-off valve 25A made of a normally open electromagnetic valve is arranged between the liquid path Pb and the liquid path Rc, and an on-off valve 25B made of a normally open type electromagnetic valve is arranged between the liquid path Rd and the liquid path Re. Be placed.

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

  When the driver steps on the brake pedal 12, the brake fluid pressure generated in the first fluid pressure chambers 13A and 13B of the master cylinder 11 is regulated by the regulator valves 61 and 61 and the in valves 42 and 42 opened by the brake fluid pressure control device 24. Is transmitted to the wheel cylinders 16, 17; 20, 21 of the disc brake devices 14, 15, 18, 19 of each wheel, and a braking force corresponding to the depression force of the brake pedal 12 can be generated.

  When it is detected that the slip ratio of one of the wheels increases and the vehicle tends to be locked based on the output of the wheel speed sensor Sa ... An ABS function that activates the hydraulic control device 24 to prevent the wheels from being locked is exhibited.

  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 transmission of the brake fluid pressure from the master cylinder 11 is shut off, and the out-valve 44 is opened. 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 Pa and Qa by the hydraulic pump 47.

  Next, the operation at the time of VSA control will be described. If the vehicle is oversteering when turning the vehicle, the wheel cylinder of the turning outer wheel is activated to generate a yaw moment that suppresses oversteering. In order to generate a yaw moment that suppresses understeer by operating the wheel cylinder, the braking force of the wheel cylinders of the left and right wheels can be individually controlled.

  That is, when the hydraulic pumps 47 and 47 are operated with the suction valves 63 and 63 excited and opened, the brake fluid is sucked from the reservoir of the master cylinder 11 through the suction valves 63 and 63. Brake fluid pressure is generated upstream. The brake fluid pressure is regulated to a predetermined level by exciting the regulator valves 61 and 61 and controlling the brake fluid pressure to a predetermined opening degree.

  In this state, the in-valve 42 corresponding to the wheel that does not need to be braked is closed so that the brake fluid pressure is not transmitted to the wheel cylinder, while the in-valve 42 that corresponds to the wheel that needs to be braked is opened. By transmitting the brake fluid pressure to the cylinder, the wheel cylinder can be operated to generate a braking force. Control of increasing / decreasing / holding the brake fluid pressure transmitted to the wheel cylinder is performed by opening and closing the in-valve 42 and the out-valve 44 as in the case of ABS control.

  In this way, by braking only one of the left and right wheels by VSA control, it is possible to generate a yaw moment in an arbitrary direction and improve the steering stability of the vehicle.

  Furthermore, the slave cylinder 23 can operate the wheel cylinders 73 and 74 of the drum brake devices 71 and 72 for the rear wheels independently of the operation of the brake pedal 12 by the driver.

  For example, when only the braking force by the above-described disc brake devices 14, 15; 18, 19 is insufficient, the drum brake devices 71, 72 that operate with the brake hydraulic pressure generated by the slave cylinder 23 generate auxiliary braking force. .

  That is, when the electric motor 52 is driven in one direction, the output shaft 59 advances through the drive bevel gear 53, the driven bevel gear 54, and the ball screw mechanism 55, so that the pair of pistons 38A and 38B pressed against the output shaft 59 Advance. Immediately after the pistons 38A and 38B start moving forward, the ports 40A and 40B connected to the fluid paths Ra and Rb are closed, so that the brake fluid pressure is generated in the second fluid pressure chambers 39A and 39B. The brake fluid pressure is transmitted to the wheel cylinders 73 and 74 of the drum brake devices 71 and 72 through the open / close valves 25A and 25B in the valve open state, and brakes the left and right rear wheels.

  Since the braking force by the slave cylinder 23 can be generated without the driver stepping on the brake pedal 12, it is suitable for the generation of the braking force in a traffic jam tracking system in which the vehicle automatically follows the preceding vehicle during traffic jams. It can be used.

  When the yaw moment generated only by the VSA control by the disk brake devices 14, 15; 18, 19 described above is insufficient, one of the left and right drum brake devices 71, 72 is operated by the brake fluid pressure generated by the slave cylinder 23. Thus, the shortage of yaw moment can be compensated. In this case, only one of the left and right drum brake devices 71, 72 is operated by opening only one of the two on-off valves 25A, 25B between the slave cylinder 23 and the left and right drum brake devices 71, 72. And yaw moment of any size can be generated.

  As described above, the disc brake devices 18 and 19 that are operated by the brake fluid pressure generated by the master cylinder 11 and the drum brake devices 71 and 72 that are operated by the brake fluid pressure generated by the slave cylinder 23 are thermally connected to each other. Since it is not affected, even when the temperature of the disc brake devices 18 and 19 activated by the driver's braking operation rises, the target braking force is accurately generated in the drum brake devices 71 and 72 that are not affected by the increase. Can do.

  If the pad clearance of the brake pad is set to be large so as to prevent the disc brake devices 14, 15; 18, 19 from being rubbed, there is a problem that the responsiveness of the braking force generation is lowered, but the brake generated by the slave cylinder 23 Since the drum brake devices 71 and 72 operated by hydraulic pressure have high responsiveness, the disc brake devices 14, 15; 18, 19 and the drum brake devices 71, 72 are used in combination, so that the disc brake devices 14, 15; High responsiveness can be ensured while preventing 19 and 19 rubbing.

  Therefore, if the drum brake devices 71 and 72 are operated at the start of the VSA control, the responsiveness of the VSA control can be improved.

  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 form of implementation is provided with the both of the disc brake devices 18, 19 and the drum brake device 71, 72 to left and right rear wheels, the front wheels or all four wheels on the disc brake device and the drum brake, Both devices may be provided.

Hydraulic circuit diagram for a normal brake system for vehicles Diagram showing structure of slave cylinder

11 Master cylinder 18 Disc brake device 19 Disc brake device 23 Slave cylinder
47 hydraulic pump 71 drum brake device 72 drum brake device

Claims (1)

At least the disc brake device (18, 19) and a drum brake device (71, 72) is provided on the right and left pair of the respective wheels, of the disc brake device (18, 19) and the drum brake device (71, 72) the disc brake device (18, 19), whereas to operate in the brake fluid pressure master cylinder (11) is generated operated by the driver's brake operation, drum brake device (71, 72), electrically actuated a brake device for the slave cylinder (23) is Ru is operated by the brake fluid pressure generated,
When the disc brake device (18, 19) performs yaw moment control for applying a braking force to one of the pair of left and right wheels during vehicle travel, the disc brake device (18, 19) of the one wheel is used. A hydraulic pump (47) capable of supplying brake hydraulic pressure is connected,
The slave cylinder (23), the brake equipment, characterized in that for supplying the brake fluid pressure in the drum brake device (71, 72) of electrically actuated the one with the wheel during the yaw moment control .

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