JP2010052504A - Brake device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the number of parts of a BBW (brake-by-wire) type brake device and simplify the structure of the device by eliminating a reservoir of a brake fluid pressure control device. <P>SOLUTION: While a first control valve 42 is opened and a second control valve 44 is opened, a braking liquid is pumped to a second liquid path S2 from a slave cylinder 23 by a liquid pressure pump 47 to increase a braking liquid pressure of the second liquid path S2, so that wheel cylinders 16, 17, 20, 21 can be actuated. Also, a specific second control valve 44 is closed and a specific first control valve 42 is closed from this condition, so that the braking liquid pressure of the specific wheel cylinder can be released to the slave cylinder 23 via the first liquid path S1, so as to independently control a braking force of each wheel cylinder and exert an ABS (anti-lock brake system) function and a VSA (vehicle stability assist) function. At that time, the liquid chamber of the slave cylinder 23 can be utilized as a reservoir, so as to eliminate a special reservoir, reduce a number of the parts and simplify the structure of the device. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a brake device including a master cylinder that generates brake fluid pressure by a driver's braking operation and a slave cylinder that has a hydraulic chamber that electrically generates brake fluid pressure in response to the braking operation.

A so-called BBW (brake-by-wire) brake device, which converts a driver's braking operation into an electrical signal to operate a slave cylinder and operates a wheel cylinder with a brake fluid pressure generated by the slave cylinder, A combination of an ABS (anti-lock braking system) device that suppresses locking and shortens the braking distance is known from Patent Document 1 below.
JP 2007-326395 A

  By the way, the ABS device combined with such a BBW brake device includes a reservoir for storing brake fluid discharged from the wheel cylinder when the brake fluid pressure of the wheel cylinder that suppresses the lock of the wheel is reduced. If this reservoir can be eliminated, the ABS device can be miniaturized.

  The present invention has been made in view of the above circumstances, and in a BBW type brake device equipped with a brake fluid pressure control device such as an ABS device or a VSA device, the reservoir of the brake fluid pressure control device is eliminated and the number of parts is reduced. The purpose is to reduce and simplify the structure.

  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 by a driver's braking operation and an electrical brake fluid pressure that is generated in response to the braking operation. A slave cylinder having a hydraulic pressure chamber, a wheel cylinder connected to the master cylinder via a hydraulic pressure chamber of the slave cylinder, a shut-off valve disposed between the master cylinder and the slave cylinder, and the slave cylinder The first and second fluid passages connecting the fluid pressure chamber and the wheel cylinder in parallel, the first control valve disposed in the first fluid passage, and the second control valve disposed in the second fluid passage And the first and second fluid passages are disposed in a third fluid passage that connects the slave cylinder side with respect to the first and second control valves, and brake fluid is transferred from the first fluid passage to the second fluid passage. Supply Brake system, characterized in that it comprises a Rueki圧 pump is proposed.

  According to the second aspect of the present invention, in addition to the configuration of the first aspect, when the brake fluid pressure of the wheel cylinder is reduced during the ABS control, the first control valve is opened and the first control valve is opened. A brake device characterized by closing the second control valve is proposed.

  According to the configuration of claim 1, with the first control valve closed and the second control valve opened, the hydraulic pump pumps up the brake fluid from the hydraulic chamber of the slave cylinder to the second hydraulic passage. The wheel cylinder can be operated by increasing the brake fluid pressure in the second fluid passage, and the wheel cylinder can be operated by closing the second control valve and opening the first control valve from this state. Since the brake fluid pressure of the wheel cylinder can be released to the fluid pressure chamber of the slave cylinder via the first fluid passage, the braking force of each wheel cylinder can be individually controlled to exhibit the ABS function and the VSA function. . At this time, since the hydraulic chamber of the slave cylinder can be used as a reservoir, the special reservoir can be eliminated to reduce the number of parts and simplify the structure.

  According to the second aspect of the present invention, the second control valve is closed and the first control valve is opened when the brake fluid pressure of the wheel cylinder is reduced during ABS control. The brake fluid pressure of the wheel cylinder that has been shut off from the first cylinder is released to the hydraulic chamber of the slave cylinder via the first control valve and the first fluid passage, and the slave cylinder can be used as a reservoir.

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

  1 to 8 show an embodiment of the present invention. FIG. 1 is a hydraulic circuit diagram of a vehicle brake device (normal and non-braking). FIG. 2 is a diagram showing the structure of a slave cylinder. 3 is a hydraulic circuit diagram showing a braking state by the slave cylinder in a normal state, FIG. 4 is a hydraulic circuit diagram showing a braking state by the master cylinder in an abnormal state, and FIG. 5 is a hydraulic circuit diagram showing an ABS control state in a normal state. 6 is a hydraulic pressure showing a VSA control state during normal braking, FIG. 7 is a hydraulic pressure showing a VSA control state during normal non-braking, and FIG. 8 is an increase in braking force during normal braking. It is a hydraulic rotation which shows a control state.

  As shown in FIG. 1, the tandem master cylinder 11 includes two hydraulic chambers 13A and 13B that output brake hydraulic pressure in accordance with the pedaling force of the driver stepping on the brake pedal 12, and one hydraulic pressure is provided. The chamber 13A is connected to the wheel cylinders 16 and 17 of the disc brake devices 14 and 15 of, for example, the left front wheel and the right rear wheel via liquid passages Pa, Pb, Pc, Pd, and Pe (first system). The 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 (second system).

  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 disposed between Pc and Qc, and an ABS (anti-lock brake system) function and a VSA (vehicle stability) are provided between the liquid paths Pc and Qc and the liquid paths Pd and Pe; Qd and Qe. A brake fluid control device 24 having an assist function is disposed. Between the upstream side and the downstream side of the shutoff valves 22A and 22B, check valves 43A and 43B that prevent the flow of hydraulic oil from the upstream side to the downstream side are arranged.

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

  As apparent from FIG. 2, the actuator 31 of the slave cylinder 23 includes a drive bevel gear 33 provided on the output shaft of the electric motor 32, a driven bevel gear 34 meshing with the drive bevel gear 33, and a ball screw mechanism operated by the driven bevel gear 34. 35.

  A rear piston 38A and a front piston 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. The rear piston 38A and the front piston A rear hydraulic chamber 39A and a front hydraulic chamber 39B are defined on the front surface of 38B. The front end of the output shaft 59 contacts the rear end of the rear piston 38A. The rear hydraulic chamber 39A communicates with the fluid paths Pb and Pc via the ports 40A and 41A, and the front hydraulic chamber 39B communicates with the fluid paths Qb and Qc via the ports 40B and 41B.

  As shown in FIG. 1, the brake hydraulic pressure control device 24 includes a first system of disc brake devices 14 and 15 for the left front wheel and the right front wheel, and a second system of disc brake devices 18 and 19 for the right front wheel and the left rear wheel. Are provided with the same structure. As a representative example, the first system of the disc brake devices 14 and 15 for the left front wheel and the right rear wheel will be described. The liquid path Pc and the liquid paths Pd and Pe are arranged in parallel with the first liquid path S1 and the second liquid. The first control valves 42 and 42, each of which is a normally open variable opening electromagnetic valve, are arranged between the first liquid path S1 and the liquid paths Pd and Pe, and are connected by the path S2. The second liquid path S2 And second fluid control valves 44 and 44, each of which is a normally open variable opening solenoid valve, are arranged between the fluid passages Pd and Pe.

  A pair of check valves 45 that permit only the flow of hydraulic oil from the first liquid path S1 side to the second liquid path S2 side in the third liquid path S3 that connects the first and second liquid paths S1, S2. A hydraulic pump 47 sandwiched between 46 is disposed, and this hydraulic pump 47 is driven by an electric motor 48. A check valve 49 is disposed between the first and second liquid passages S1 and S2 to prevent the hydraulic fluid from flowing from the second liquid passage S2 side to the first liquid passage S1 side. Further, in the second liquid passage S2 close to the connection portion between the first liquid passage S1 and the liquid passage Pc, the flow of hydraulic oil from the first liquid passage S1 and the liquid passage Pc side to the second liquid passage S2 side is prevented. A relief valve 50 is arranged.

  In 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 brake fluid pressure control device 24, the fluid pressure that detects the brake fluid pressure generated by the master cylinder 11 is included. A sensor Sa, a hydraulic pressure sensor Sb that detects a brake hydraulic pressure transmitted to the first hydraulic path S1, a hydraulic pressure sensor Sc that detects a brake hydraulic pressure transmitted to the second hydraulic path S2, and a wheel of each wheel A wheel speed sensor Sd for detecting the speed is connected.

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

  As shown in FIG. 3, when the system functions normally, the shutoff valves 22A and 22B made of normally open solenoid valves are excited and closed, and the reaction force permission valve 25 made of normally closed solenoid valves is excited. It is opened. In this state, when the hydraulic pressure sensor Sa provided in the liquid path Pa detects that the driver depresses the brake pedal 12, the actuator 31 of the slave cylinder 23 is operated, and the rear and front pistons 38A and 38B move forward. Brake hydraulic pressure is generated in the rear and front hydraulic chambers 39A and 39B. The brake fluid pressure is supplied via the first fluid passage S1 of the brake fluid pressure control device 24 and the opened first control valves 42, 42, or the check valve 49, the second fluid passage S2, and the opened second control valve. 44, 44 is transmitted to the wheel cylinders 16, 17, 20, 21 of the disc brake devices 14, 15, 18, 19 to brake each wheel.

  Since the shutoff valves 22A and 22B are closed, the brake fluid pressure generated by the master cylinder 11 is not transmitted to the disc brake devices 14, 15, 18, and 19. At this time, the brake hydraulic pressure generated in one hydraulic chamber 13A of the master cylinder 11 is transmitted to the hydraulic chamber 30 of the stroke simulator 26 via the opened reaction force permission valve 25, and the piston 29 is transferred to the spring 28. By moving it against, the stroke of the brake pedal 12 can be allowed and a pseudo pedal reaction force can be generated to eliminate the driver's uncomfortable feeling.

  The brake fluid pressure by the slave cylinder 23 detected by the fluid pressure sensors Sb and Sc provided in the first and second fluid passages S1 and S2 is braked by the master cylinder 11 detected by the fluid pressure sensor Sa provided in the fluid passage Pa. By controlling the operation of the actuator 31 of the slave cylinder 23 so as to have a magnitude corresponding to the hydraulic pressure, the braking force corresponding to the pedaling force input to the brake pedal 12 by the driver is applied to the disc brake devices 14, 15, 18. , 19 can be generated.

  In the case of an electric vehicle or a hybrid vehicle, regenerative braking is preferentially used in order to increase energy recovery efficiency by regenerative braking, and a deficiency in braking force due to regenerative braking is compensated by a braking force due to hydraulic pressure. In such a case, the brake fluid pressure generated by the slave cylinder 23 is kept low with respect to the magnitude of the brake fluid pressure by the master cylinder 11 detected by the fluid pressure sensor Sa provided in the fluid passage Pa. The braking force due to pressure can be reduced.

  In the case of an abnormality such as a power supply failure, as shown in FIG. 4, the shutoff valves 22A and 22B made of a normally open solenoid valve are automatically opened, and the reaction force permission valve 25 made of a normally closed solenoid valve is The first control valves 42 and 42 made of a normally open solenoid valve are automatically opened, and the second control valves 44 and 44 made of a normally open solenoid valve are automatically closed. . In this state, the brake hydraulic pressure generated in the two hydraulic chambers 13A and 13B of the master cylinder 11 is not absorbed by the stroke simulator 26, and the rear and front hydraulic pressures of the shutoff valves 22A and 22B and the slave cylinder 23 are detected. Passing through the chambers 39A and 39B and the brake fluid pressure control device 24, the wheel cylinders 16, 17, 20, and 21 of the disc brake devices 14, 15, 18, and 19 of each wheel are operated to generate a braking force without any trouble. Can do.

  As shown in FIG. 5, when the braking is normally performed with the brake fluid pressure generated by the slave cylinder 23, the slip ratio of any wheel increases based on the output of the wheel speed sensor Sd, and the lock tendency tends to occur. Is detected, the shut-off valves 22A and 22B made up of normally-open solenoid valves are excited and closed, and the operation of the slave cylinder 23 is stopped. In this state, the brake fluid pressure control device 24 exhibits the ABS function. Let the wheel lock.

  For example, when the left front wheel tends to lock, the hydraulic pump 47 is driven by the electric motor 48 in a state where all the first control valves 42 are closed, and brake fluid is discharged from the rear hydraulic chamber 39A of the slave cylinder 23. By pumping up and increasing the brake fluid pressure in the second fluid passage S2, the brake fluid pressure generated by the hydraulic pump 47 is transmitted to the wheel cylinders 16, 17, 20, 21 instead of the brake fluid pressure generated by the slave cylinder 23. To do. Then, by closing only the second control valve 44 of the left front wheel that has become locked and opening only the first control valve 22, the first control valve 42 that opens the brake fluid pressure of the wheel cylinder 16 and A pressure reducing action for releasing to the rear hydraulic pressure chamber 39A of the slave cylinder 23 through the first liquid passage S1 is performed. Subsequently, the first control valve 42 is closed to perform a holding action of holding the brake fluid pressure of the wheel cylinder 16, thereby reducing the braking force so that the left front wheel is not locked.

  As a result, when the wheel speed of the left front wheel recovers and the slip ratio decreases, the second control valve 44 of the left front wheel is opened, and the hydraulic pressure is increased by the operation of the hydraulic pump 47. The braking force of the left front wheel is increased by performing a pressure increasing action to communicate with the wheel cylinder 16. When the left front wheel tends to lock again due to 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 locking of the left front wheel by repeating the operation.

  When the pressure reducing action and the pressure increasing action are performed, the rear hydraulic pressure chamber 39A of the slave cylinder 23 is used as a reservoir, so that it is not necessary to provide a special reservoir, thereby reducing the number of parts and simplifying the structure. Can do.

  When the slave cylinder 23 is used as a reservoir, the volume of the rear hydraulic chamber 39A and the front hydraulic chamber 39B can be freely expanded and reduced if the electric motor 48 can be rotated without load. Can do.

  The ABS function when the left front wheel tends to lock has been described above, but the ABS function when the other wheels tend to lock is also the same.

  While the brake hydraulic pressure control device 24 performs the ABS function described above, the shutoff valves 22A and 22B are maintained in the closed state, so that the hydraulic pressure change due to the operation of the brake hydraulic pressure control device 24 is kicked back. Thus, transmission from the master cylinder 11 to the brake pedal 12 can be prevented.

  As shown in FIG. 6, the brake fluid pressure control is performed with the shut-off valves 22A and 22B composed of normally-open electromagnetic valves being excited and closed at normal times when braking is performed with the brake fluid pressure generated by the slave cylinder 23. The device 24 can exert a VSA function for assisting turning of the vehicle by increasing and decreasing only the braking force of a specific wheel.

  For example, when assisting the vehicle to turn right by increasing the braking force of the right rear wheel and decreasing the braking force of the left front wheel at the diagonal position, basically all the first control valves 42. In the state where the second control valve is closed and the hydraulic pump 47 is driven to increase the brake fluid pressure in the second fluid passage S2, only the second control valve 44 of the right rear wheel is opened and the right rear is opened. A yaw moment in the right turn direction can be generated by increasing the braking force of the wheel and reducing only the braking force of the left front wheel by opening only the first control valve 42 of the left front wheel.

  Even when the brake fluid pressure control device 24 performs the above-described VSA function, the rear fluid pressure chamber 39A of the slave cylinder 23 is used as a reservoir, so there is no need to provide a special reservoir, and the number of parts can be reduced. The structure can be simplified.

  The VSA function when assisting a right turn has been described above, but the same applies to the VSA function when assisting a left turn.

  While the brake hydraulic pressure control device 24 performs the above-described VSA function, the shutoff valves 22A and 22B are maintained in the closed state, so that the hydraulic pressure change due to the operation of the brake hydraulic pressure control device 24 is kicked back. Thus, transmission from the master cylinder 11 to the brake pedal 12 can be prevented.

  As shown in FIG. 7, even when the driver is not stepping on the brake pedal 12, the brake fluid pressure control device 24 is in a state in which the shutoff valves 22A and 22B composed of normally open solenoid valves are excited and closed. Thus, the VSA function for assisting turning of the vehicle by increasing only the braking force of a specific wheel can be exhibited.

  For example, when assisting a left turn of the vehicle by increasing only the braking force of the left front wheel, the hydraulic pump 47 is driven to increase the brake fluid pressure in the second fluid path S2, and other than the left front wheel. By closing the second control valves 44 of the wheels and closing only the first control valve 42 of the left front wheel, only the braking force of the left front wheel can be increased and the VSA function can be exhibited.

  As shown in FIG. 8, when braking is performed with the brake hydraulic pressure generated by the slave cylinder 23 when the system is normal, the hydraulic pump 47 is driven with all the first control valves 42 closed. The brake hydraulic pressure generated by the slave cylinder 23 can be further increased by the hydraulic pump 47 to increase the braking force of the four wheels.

  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.

Hydraulic circuit diagram of vehicle brake system (normal and non-braking) Diagram showing structure of slave cylinder Hydraulic circuit diagram showing braking condition by slave cylinder at normal time Hydraulic circuit diagram showing the braking state by the master cylinder at the time of abnormality Hydraulic circuit diagram showing the ABS control state under normal conditions Hydraulic pressure indicating the VSA control state during normal braking Hydraulic pressure indicating the VSA control state during normal non-braking Hydraulic pressure indicating the braking force increase control state during normal braking

Explanation of symbols

11 Master cylinder 16 Wheel cylinder 17 Wheel cylinder 20 Wheel cylinder 21 Wheel cylinder 22A Shut-off valve 22B Shut-off valve 23 Slave cylinder 31 Actuator 39A Rear hydraulic chamber (hydraulic chamber)
39B Front hydraulic chamber (hydraulic chamber)
42 1st control valve 44 2nd control valve 47 Hydraulic pump S1 1st liquid path S2 2nd liquid path S3 3rd liquid path

Claims (2)

A master cylinder (11) for generating a brake fluid pressure by a driver's braking operation;
A slave cylinder (23) having hydraulic chambers (39A, 39B) for generating brake hydraulic pressure electrically in response to the braking operation;
Wheel cylinders (16, 17, 20, 21) connected to the master cylinder (11) via hydraulic chambers (39A, 39B) of the slave cylinder (23);
Shut-off valves (22A, 22B) disposed between the master cylinder (11) and the slave cylinder (23);
First and second fluid passages (S1, S2) connecting the hydraulic chambers (39A, 39B) of the slave cylinder (23) and the wheel cylinders (16, 17, 20, 21) in parallel;
A first control valve (42) disposed in the first liquid path (S1);
A second control valve (44) disposed in the second liquid path (S2);
The first and second fluid passages (S1, S2) are arranged in a third fluid passage (S3) connecting the slave cylinder (23) side with respect to the first and second control valves (42, 44). A hydraulic pump (47) for supplying brake fluid from the first fluid passage (S1) to the second fluid passage (S2);
A brake device comprising:   When the brake fluid pressure of the wheel cylinder (16, 17, 20, 21) is reduced during the ABS control, the first control valve (42) is opened and the second control valve (44) is closed. The brake device according to claim 1, wherein:

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