JPH10194112A - Brake system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a screw mechanism from being locked to prevent the malfunction of a brake actuator even when the fluid pressure is produced by a master cylinder when the operation of the brake actuator is released. SOLUTION: In a brake system 1 where a brake actuator 6 for producing the fluid pressure in response to a command from outside to supply the fluid pressure to a wheel cylinder 8 is provided between a master cylinder 3 and the wheel cylinder 8, an interrupting mechanism 37 for preventing the flow of working fluid flowing from the master cylinder 3 to a fluid pressure chamber of the brake actuator 6 in response to the operation of the brake actuator 6, is provided. Thus, when the operation of the brake actuator 6 is released, the fluid pressure produced by the master cylinder 3 is prevented from acting on the fluid pressure chamber of the brake actuator 6 to lock a screw mechanism, and thereby the malfunction of the brake system 1 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake system used for a vehicle or the like, and more particularly, to a brake system for automatically applying a brake to a vehicle or the like regardless of a driver's operation.

[0002]

2. Description of the Related Art Japanese Patent Laid-Open No.
No. 216846. This publication discloses a main body having a cylinder hole formed between a master cylinder and a wheel cylinder, and a hydraulic chamber which is slidably inserted into the cylinder hole and communicates with the wheel cylinder and the master cylinder in the cylinder hole. There is disclosed a brake system in which a brake actuator having a piston that performs rotation and a screw mechanism that converts a rotational force of an external drive source that rotates in response to an external command into a linear motion of the piston is disposed.

In this brake system, hydraulic pressure generated in a master cylinder is supplied to a wheel cylinder via a hydraulic chamber of a brake actuator. The brake actuator is used, for example, as a brake assist device such as a parking brake safety device or a slope start assist device, or as a brake control device that actively controls brake fluid pressure to perform traction control of wheels.

[0004]

The piston of the brake actuator generates hydraulic pressure by reducing the volume of the hydraulic chamber by a screw mechanism that converts the rotational force of an external drive source into a linear motion of the piston. When the operation of the actuator is released, that is, when the volume of the hydraulic chamber is increased and the hydraulic pressure is reduced, when hydraulic pressure is generated by the master cylinder, a high pressure is generated in the hydraulic chamber of the brake actuator, and this high pressure is applied to the piston of the brake actuator. Act on. As a result, the acting force on the piston of the brake actuator is transmitted to the screw mechanism driven in the same direction as the acting force. At this time, if the driving force of the external drive source is small, the screw mechanism may be fixed (locked), and the entire brake system may malfunction. In particular, such a problem is likely to occur when the screw mechanism is used to prevent the movement of the piston due to the acting force from the hydraulic chamber side as in the above-described related art.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has a brake system capable of preventing a malfunction due to a screw mechanism portion being stuck even when a hydraulic pressure is generated by a master cylinder when the brake actuator is deactivated. The task is to provide

[0006]

The above object is attained by claim 1.
According to the invention, a master cylinder that generates a hydraulic pressure in accordance with a driver's operation, a wheel cylinder that generates a braking force by the hydraulic pressure from the master cylinder, and between the master cylinder and the wheel cylinder A brake actuator provided to generate a hydraulic pressure in response to an external command and to supply the hydraulic pressure to a wheel cylinder, wherein the brake actuator comprises: a main body having a cylinder hole; A piston which is slidably inserted in the cylinder hole and defines a hydraulic chamber communicating with the wheel cylinder and the master cylinder in a cylinder hole, and a rotational force of an external drive source which rotates according to a command from the outside. A brake system having a screw mechanism for converting to linear motion. Braking system provided with a blocking mechanism for blocking the flow of hydraulic fluid toward the hydraulic pressure chamber from the master cylinder in response to operation, is solved by.

In the brake system according to the first aspect of the present invention, even if a hydraulic pressure is generated by the master cylinder when the operation of the brake actuator is released, the high pressure is not applied to the hydraulic pressure chamber by the shut-off mechanism, so that the brake actuator is operated. At the time of release, malfunction of the brake system due to sticking of the screw mechanism is prevented.

According to a fourth aspect of the present invention, there is provided a master cylinder for generating a hydraulic pressure in response to a driver's operation, and a wheel cylinder for generating a braking force by the hydraulic pressure from the master cylinder. A brake actuator that is provided between the master cylinder and the wheel cylinder and generates a hydraulic pressure in accordance with an external command and supplies the wheel cylinder with the hydraulic pressure, wherein the brake actuator is A main body having a cylinder hole, a piston slidably inserted into the cylinder hole and defining a hydraulic chamber communicating with the wheel cylinder and the master cylinder in the cylinder hole, and in response to a command from the outside. A screw mechanism for converting a torque of a rotating external drive source into a linear motion of the piston. In the liquid pressure generated by the master cylinder is at or over a predetermined pressure, the braking system provided with a blocking mechanism for blocking the flow of hydraulic fluid from the master cylinder toward the brake actuator is solved by.

In the brake system according to a fourth aspect of the present invention, the hydraulic pressure higher than a predetermined pressure generated by the master cylinder is prevented from acting on the hydraulic chamber of the brake actuator by the shutoff mechanism. It prevents the malfunction of the brake system due to the sticking of the mechanism. This configuration is preferably applied to the rear wheel side.

According to the present invention, there is provided a master cylinder for generating a hydraulic pressure in response to a driver's operation, and a wheel cylinder for generating a braking force by the hydraulic pressure from the master cylinder. A brake system comprising: a brake actuator connected to a pipe connecting the master cylinder and the wheel cylinder via a branch path to generate a hydraulic pressure in accordance with an external command and to supply the hydraulic pressure to the wheel cylinder; Wherein the brake actuator has a body formed with a cylinder hole, and a piston which is slidably inserted into the cylinder hole and defines a hydraulic chamber communicating with the wheel cylinder and the master cylinder in the cylinder hole. A screw mechanism that converts the torque of an external drive source that rotates in response to an external command into linear motion of the piston A brake system having a brake system provided with a check valve to a direction toward the wheel cylinder from the brake actuator to said branch path and forward, is solved by.

In the brake system according to the sixth aspect of the present invention, the hydraulic pressure generated by the master cylinder is prevented from acting on the hydraulic pressure chamber of the brake actuator by the check valve provided in the branch passage, and the operation of the brake actuator is released. At this time, malfunction of the brake system due to the fixation of the screw mechanism is prevented.

According to a ninth aspect of the present invention, there is provided a master cylinder for generating a hydraulic pressure in response to a driver's operation, and a wheel cylinder for generating a braking force by the hydraulic pressure from the master cylinder. A brake system comprising: a brake actuator connected to a pipe connecting the master cylinder and the wheel cylinder via a branch path to generate a hydraulic pressure in accordance with an external command and to supply the hydraulic pressure to the wheel cylinder; Wherein the brake actuator has a body formed with a cylinder hole, and a piston which is slidably inserted into the cylinder hole and defines a hydraulic chamber communicating with the wheel cylinder and the master cylinder in the cylinder hole. A screw mechanism that converts the torque of an external drive source that rotates in response to an external command into linear motion of the piston In the brake system, the branch path receives the hydraulic pressure on the wheel cylinder side on the small diameter side, receives the pressure on the brake actuator side on the large diameter side, and acts on the small diameter side and the large diameter side. The brake system is provided with a cylinder device having a stepped piston movable in accordance with the acting force.

In the brake system according to the ninth aspect of the present invention, even when the hydraulic pressure is generated in the master cylinder, a high hydraulic pressure is not applied to the hydraulic chamber of the brake actuator due to the pressure receiving area difference of the stepped piston. When the operation is released, malfunction of the brake system due to sticking of the screw mechanism is prevented.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a brake system according to each embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a piping system diagram of a brake system according to a first embodiment of the present invention, which is indicated by 1 as a whole. The hydraulic pressure generated in one of the hydraulic pressure generating chambers of the master cylinder 3 by the operation of the brake pedal 2 is supplied to the wheel cylinder 8 via the pipeline 4, the brake actuator 6 having a shutoff mechanism 37 described later, and the pipeline 7. It has become so. The hydraulic pressure generated in the other hydraulic pressure generating chamber supplies the hydraulic pressure to a wheel cylinder of another system (not shown) via the pipe 5.

FIG. 2 shows a brake actuator 6 according to the present embodiment. The brake actuator 6 rotates a drive shaft 15 by driving a motor 17 as an external drive source that rotates in response to an external command. This is a device that converts the rotational force into a linear motion of the piston 13 to generate a hydraulic pressure in the hydraulic pressure chamber 30 and supplies the hydraulic pressure to the pipe 7 via the output port 51. Hereinafter, this will be described.

A cylinder hole 12 is formed inside the main body 11, into which a piston 13 with cup seals 27 and 28 is slidably inserted. A return spring 26 is disposed in the hydraulic chamber 30 defined between the piston 13 and the bottom wall of the cylinder hole 12, and biases the piston 13 rightward in the drawing. A center valve mechanism that closes when the piston 13 moves in the direction of reducing the volume of the hydraulic chamber 30, that is, when the piston 13 moves to the left in the drawing, is provided in the recess 54 formed at the end of the piston 13 on the hydraulic chamber 30 side. 53 are provided. A communication chamber 35 that communicates with the master cylinder 3 via a shut-off mechanism 37 described below is defined on the outer peripheral portion of the piston 13 defined between the cup seals 27 and 28. It communicates with the hydraulic chamber 30.

The center valve mechanism 53 has a valve body 31 which can be attached to and detached from a valve seat 36 formed at the bottom of the recess 54, and is provided integrally with the valve body 31 and penetrates the axis of the piston 13. It has a stem 32, a valve spring 33 for urging the valve element 31 in the direction of the valve seat 36, and a retainer 34 for supporting one end of the valve spring 33. When the piston 13 shown in FIG. When the end of the stem 32 abuts on the pin member 29 that passes through the long hole 45 of the thirteen and whose both ends are supported by the main body 11, the valve element 31 is separated from the valve seat 36 and is in an open state. . Next, the screw mechanism 14 will be described.

A bolt 15a of the drive shaft 15 is loosely fitted to the rear end of the piston 13, and a nut member 16 is screwed into the bolt 15a. The outer peripheral surface of the nut member 16 has a non-circular shape. The outer peripheral surface is non-rotatably supported by a sleeve 25 having an inner peripheral portion 25a substantially matching this shape. It is adapted to be moved along the portion 25a. The rotation of the drive shaft 15 in the forward direction causes the nut member 16 to rotate.
Abuts against the rear end of the piston 13 to move the piston to the left in the drawing against the spring force of the return spring 26, and to return the piston 13 to the inoperative position by the reverse rotation of the drive shaft 15. It has become. The return position of the nut member 16 is determined by a stopper member 24 fixed to the drive shaft 15.
It is performed by

The drive shaft 15 is supported by a support member 21 for fixing the main body 11 to the base 46 via a bearing 23, and a large-diameter gear 20 is fixed to a rear end thereof. Further, a motor 17 driven based on an external command is fixed to the base 46, and a small-diameter gear 19 is fixed to a rotating shaft thereof. The teeth of the small-diameter gear 19 and the teeth of the large-diameter gear 20 are engaged with each other, and the rotational drive of the motor 17 is transmitted to the drive shaft 15 via the small-diameter gear 19 and the large-diameter gear 20. ing. The gear mechanism is a cover 2 fixed to the base 46 by a screw member 47.
2 is covered.

Next, a description will be given of a shut-off mechanism 37 for preventing the flow of the brake hydraulic fluid from the master cylinder 3 toward the hydraulic chamber 30 in response to the operation of the brake actuator 6 configured as described above.

The blocking mechanism 37 is provided on the input side boss 4 of the main body 11.
8 are provided. An input port 50 to which the pipeline 4 is connected is formed in the plug member 42 which is screwed and fixed to the opening of the boss portion 48 via the seal ring 44.
The lower end of the plug member 42 supports the valve seat forming member 39 in which the boss 48 is fitted via the seal ring 43,
The valve seat 39 is located between the plug member 42 and the valve seat forming member 39.
A spherical valve element 40 urged by a valve spring 41 in the direction of a
Are arranged. When the illustrated brake actuator 6 is not operated, the valve body 40 penetrates a passage 55 including a center hole of the valve seat forming member 39 and a through hole formed in the main body in alignment with the center hole. It is separated from the valve seat 39a by a valve opening member 38 whose lower end abuts on the engaged portion 13a formed in a tapered shape. A plurality of grooves are formed in the outer periphery of the valve opening member 38 along the axial direction, and the master cylinder 3 side and the communication chamber 35 communicate with each other via the plurality of grooves. However, piston 13
Moves to the left in the figure, the valve opening member 38
The valve body 40 is guided by the engaged portion 13a of FIG.
Is seated on the valve seat 39a, whereby the fluid communication in the direction from the master cylinder 3 to the communication chamber 35 is cut off.

The brake system 1 according to the present embodiment is configured as described above, and the operation will be described below.

Now, it is assumed that the vehicle is parked on the road. Assuming that the vehicle starts moving due to insufficient pulling of the parking brake lever, the motor 17 of the brake actuator 6 is driven based on an external command that is detected and output. The rotational drive of the motor 17 is transmitted to the drive shaft 15 via the small-diameter gear 19 and the large-diameter gear 20, and the rotational force of the drive shaft 15 is converted into linear motion of the piston 13 by the screw mechanism 14. That is, the piston 13 is moved leftward in FIG. 2 along the cylinder hole 12. As a result, the hydraulic pressure generated in the hydraulic chamber 30 is transmitted from the output port 51 to the wheel cylinder 9 via the pipe 7.
a, 9b. Therefore, even if the driver does not operate the brake pedal 2, the wheel cylinders 9a, 9b
The brake fluid pressure can be supplied to the vehicle, and the vehicle can be surely prevented from inadvertently starting to move. When the brake actuator 6 is operating, the valve body 40 of the shutoff mechanism 37 is seated on the valve seat 39a by the downward movement of the valve opening member 38, and the fluid communication from the master cylinder 3 to the communication chamber 35 is established. It is shut off.

When the condition for releasing the operation of the brake actuator 6 is satisfied, a brake release command is supplied to the motor 17, whereby the piston 13 starts to return to the inoperative position shown in the figure. When the brake is released, the direction of the reaction force from the hydraulic chamber 30 and the biasing direction of the return spring 26 are the same as the direction in which the nut member 16 moves in the screw mechanism 14. At this time, when a large force acts on the hydraulic chamber 30, the engaging portions (threads) between the bolt portion 15a of the drive shaft 15 and the nut member 16 in the screw mechanism 14 engage with each other and are fixed (locked) as described above. Have the problem of In this case, if the driving force of the motor 17 is increased, the drive shaft 15 may be rotationally driven with a large force.
If the driving force of the brake actuator 7 is increased, the size of the brake actuator 6 as a whole increases. However, if the driving force is small, the screw mechanism 14 may be kept fixed, which may cause malfunction of the entire brake system.

However, according to the present embodiment, even if the driver depresses the brake pedal 2 to generate the brake fluid pressure for some reason when the brake actuator 6 is deactivated, the shut-off mechanism 37 according to the present invention causes the passage. 55
The hydraulic pressure from the master cylinder 3 is prevented from being transmitted to the hydraulic pressure chamber 30 by opening the center valve mechanism 53 since the hydraulic pressure is prevented from flowing into the communication chamber 35 through the
The force generated by the high-pressure brake fluid acting on the fluid pressure chamber 30 is not transmitted to the screw mechanism 14. Therefore, even when a hydraulic pressure is generated by the master cylinder 3 when the operation of the brake actuator 6 is released, a high pressure is not applied to the hydraulic pressure chamber 30, so that the malfunction of the entire brake system 1 due to the fixing of the screw mechanism 14 is prevented. be able to.

FIG. 3 shows a piping system diagram of a brake system according to a second embodiment of the present invention, the whole being 61%.
Indicated by FIG. 4 shows the details of the brake actuator 62 according to the present embodiment, except that the blocking mechanism 37 is removed from the brake actuator 6 according to the first embodiment, and the input port 50 ′ is formed in the main body 11 ′. Only the difference is that the other parts have the same configuration. 1 or 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.

That is, in this embodiment, when the hydraulic pressure generated by the master cylinder 3 becomes higher than a predetermined pressure between the master cylinder 3 and the brake actuator 62, the master cylinder 3
There is provided a shut-off mechanism 63 for preventing the flow of the working fluid toward the flow path. The shutoff mechanism 63 has a movable body 65 that receives the hydraulic pressure from the master cylinder 3 at one end and receives the spring force of the spring 66 at the other end, and is slidably disposed in the casing 64 via the seal ring 71. When the hydraulic pressure from the master cylinder 3 is lower than a predetermined pressure (determined by the spring force of the spring 66), the spring force of the valve spring 68 that urges the shaft portion 65a of the movable body 65 toward the valve seat 70 is used. The spherical valve body 67 is separated from the valve seat 70 against the pressure. The shutoff mechanism 63 and the input port 5 of the brake actuator 62 thus configured
0 'is connected via a pipe 69.

According to the present embodiment, when the operation of the brake actuator 62 is released, even if a hydraulic pressure is generated in the master cylinder 3 due to the depression of the brake pedal 2 by the driver, the hydraulic pressure is not less than the predetermined pressure. Then, the movable body 65 in the shut-off mechanism 63 moves in the direction opposing the spring force of the spring 66, thereby seating the valve body 67 on the valve seat 70, thereby shutting off liquid communication between the master cylinder 3 and the brake actuator 62. Therefore, it is possible to prevent the high hydraulic pressure equal to or higher than the predetermined pressure from being transmitted to the hydraulic pressure chamber 30 of the brake actuator 62, and it is possible to avoid a malfunction due to the fixing of the screw mechanism 14 in the brake actuator 62. Further, according to the present embodiment, since the shut-off mechanism 63 performs the same operation as a so-called pressure reducing proportional valve, it is preferable that the shut-off mechanism 63 is provided on the rear wheel side that does not require a strong braking force.

FIG. 5 shows a piping system diagram of a brake system according to a third embodiment of the present invention, the whole being 75%.
Indicated by Parts corresponding to those in FIG. 3 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In this embodiment, unlike the first and second embodiments described above, the brake actuator 62 is connected via a branch passage 78 to a pipe communicating between the master cylinder 3 and the wheel cylinder 8. Have been. An input port 50 ′ of the brake actuator 62 is connected to a hydraulic fluid reservoir 3 a connected to the master cylinder 3 via a pipe 80, and a branch path 78 is connected to the output port 51. A check valve 79 having a forward direction from the brake actuator 62 toward the wheel cylinder 8 is provided in the branch passage 78. Further, between the master cylinder 3 and the wheel cylinder 8, the two are normally connected to each other at the position A, but the solenoid 76 a receives an external signal transmitted in response to the stop of the vehicle. A shut-off valve device 76 that switches to the position B and blocks the flow of hydraulic fluid from the wheel cylinder 8 side to the master cylinder 3 side.
Is provided. The shutoff valve device 76 and the wheel cylinder 8 are connected via a pipe 77 from which a branch path 78 branches.

According to the present embodiment, even when brake hydraulic pressure is generated in the master cylinder 3 when the operation of the brake actuator 62 is released, the check valve 79 provided in the branch passage 78 supplies the brake hydraulic pressure to the brake actuator 62. Since the pressure can be prevented from being transmitted, the hydraulic pressure generated in the master cylinder 3 causes the brake actuator 6
The second screw mechanism 14 is not fixed, so that the brake system 75 does not malfunction.

In this embodiment, when the brake actuator 62 operates (the vehicle is stopped), the shut-off valve device 76 is switched to the position B by receiving an external signal from its solenoid 76a. It acts so as to prevent the generated hydraulic pressure from flowing to the master cylinder 3 side. Furthermore, by switching the shutoff valve device 76 to the position B when the vehicle starts on a slope, the vehicle can be easily started only by operating the accelerator pedal and the clutch pedal without the need to continuously depress the brake pedal. When the vehicle starts moving, the shut-off valve device 76 switches to the position A, and the master cylinder 3 and the wheel cylinder 8 communicate with each other.

FIG. 6 shows a piping system diagram of a brake system according to a fourth embodiment of the present invention.
Indicated by That is, in the present embodiment, the check valve 79 in FIG.
One of the two input sections is connected to the brake actuator 62 side, the other is connected to the master cylinder 3 side, and the output section is connected to the wheel cylinder 8 side.

That is, according to the present embodiment, the higher of the brake actuator 62 side and the master cylinder 3 side is supplied to the wheel cylinder 8 by the action of the double check valve 83. , Normal braking and brake actuator 6
2, the brake action can be performed without any problem, and the hydraulic pressure generated in the master cylinder 3 is not transmitted to the brake actuator 62. Therefore, the same effect as in the third embodiment described above is obtained. Can be obtained. Further, the hydraulic pressure generated when the brake actuator 62 is operated can be supplied to the wheel cylinder 8 without flowing out to the master cylinder 3 side.

FIG. 7 shows a piping system diagram of a brake system according to a fifth embodiment of the present invention, the entirety of which is shown in FIG.
Indicated by Parts corresponding to those in FIG. 5 are denoted by the same reference numerals, and detailed description thereof will be omitted.

That is, in the present embodiment, the check valve 79 in FIG. The cylinder device 88 is provided in the branch passage 78 and has a small diameter portion 90a.
And seal rings 91 and 92 on the large diameter portion 90b, respectively.
And a stepped piston 90 which is slidably disposed in a casing 89 with the mounting. The small-diameter portion 90a of the stepped piston 90 receives the hydraulic pressure on the wheel cylinder 8 side, the large-diameter portion 90b receives the pressure on the brake actuator 62 side, and the small-diameter portion 90a and the large-diameter portion 90b.
The inside of the casing 89 can be moved according to the acting force acting on the b side. In this embodiment, the spring 93 is provided between the casing 89 and the large-diameter portion 90b of the stepped piston 90. However, this may be omitted as necessary.

According to the present embodiment, when the brake actuator 62 is released from operation, even if a hydraulic pressure is generated in the master cylinder 3, the hydraulic pressure is applied to the small diameter portion 90 a of the stepped piston 90 and the large diameter in the cylinder device 88. The pressure is reduced based on the pressure receiving area difference between the brake actuator 6 and the brake actuator 6.
2, the high hydraulic pressure does not act on the hydraulic chamber 30 of the brake actuator 62.
Therefore, when the operation of the brake actuator 62 is released, the screw mechanism 14 does not stick due to the hydraulic pressure generated in the master cylinder 3, and the brake system 87 does not malfunction. Conversely, when the brake actuator operates, the hydraulic pressure generated thereby is amplified based on the pressure receiving area difference of the stepped piston 90 and supplied to the wheel cylinder 8, so that the driving force can be reduced accordingly. it can. The master cylinder 3 and the wheel cylinder 8
Since the shut-off valve device 76 provided between them is configured in the same manner as in the above-described third embodiment and performs the same operation, the description thereof is omitted here.

Although the brake system according to each embodiment of the present invention has been described above, the present invention is, of course, not limited to these, and various modifications can be made based on the technical concept of the present invention.

For example, in the above-described first embodiment, the shut-off mechanism 37 is configured such that the valve body 40 is separated from and seated on the valve seat 39a in accordance with the movement of the piston 13 in the brake actuator 6, but instead of this, When the brake actuator 6 is actuated, the shutoff mechanism may be configured by an electromagnetic valve that switches to a position where the flow of the hydraulic fluid from the master cylinder 3 toward the hydraulic chamber 30 of the brake actuator 6 is blocked. In this case, for example, an external signal transmitted to the motor 17 of the brake actuator 6 may be supplied to the solenoid portion of the solenoid valve, and the solenoid valve may be switched according to the signal.

In the first, third to fifth embodiments described above, there is no mention as to whether the wheel cylinder 8 is applied to the front wheels or to the rear wheels. Either one may be used, or both may be applied. Further, although only one wheel cylinder 8 is shown, the invention may be applied to the left and right front wheels or the left and right rear wheels in common.

Further, the brake actuator 62 described in the second to fifth embodiments may be applied in place of a conventionally known brake actuator which converts the rotation of a screw into a linear motion of a piston. Often,
In this case, of course, a similar effect can be obtained.

[0043]

As described above, according to the brake system of the first aspect of the present invention, the shut-off for preventing the flow of the hydraulic fluid from the master cylinder to the hydraulic chamber of the brake actuator in response to the operation of the brake actuator. Since the mechanism is provided, even if hydraulic pressure is generated by the master cylinder when the brake actuator is deactivated, high pressure does not act on the hydraulic pressure chamber, so the screw mechanism does not stick and the brake system malfunctions Will not be.

According to the brake system of the fourth aspect of the present invention, when the hydraulic pressure generated by the master cylinder becomes equal to or higher than a predetermined pressure, the shut-off mechanism for preventing the flow of the hydraulic fluid from the master cylinder to the brake actuator is provided. As a result, the hydraulic pressure higher than the predetermined pressure generated by the master cylinder does not act on the hydraulic chamber of the brake actuator, so that the screw mechanism is stuck by the hydraulic pressure generated by the master cylinder when the brake actuator is released. And the brake system does not malfunction.

According to the brake system of the sixth aspect of the present invention, the check valve is provided on the branch of the passage connecting the master cylinder and the wheel cylinder, the forward direction being from the brake actuator toward the wheel cylinder. Therefore, the hydraulic pressure generated by the master cylinder does not act on the hydraulic pressure chamber of the brake actuator, so that the screw mechanism does not stick due to the hydraulic pressure generated by the master cylinder when the brake actuator is deactivated, and the brake system operates. It will not be defective.

Further, according to the brake system of the present invention, the branch pressure of the passage connecting the master cylinder and the wheel cylinder receives the hydraulic pressure on the wheel cylinder side on the small diameter side and the brake actuator on the large diameter side. The cylinder device has a stepped piston that can move according to the acting force acting on the small-diameter side and the large-diameter side while receiving the pressure on the side of the master cylinder. No high hydraulic pressure is generated in the hydraulic pressure chamber of the brake actuator due to the difference in the pressure receiving area of the piston, so that the screw mechanism does not stick due to the hydraulic pressure generated in the master cylinder when the brake actuator is deactivated, and the brake system is not operated. There is no malfunction.

[Brief description of the drawings]

FIG. 1 is a piping diagram of a brake system according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing details of a brake actuator in FIG. 1;

FIG. 3 is a piping diagram of a brake system according to a second embodiment of the present invention.

FIG. 4 is an enlarged sectional view showing a brake actuator according to second to fifth embodiments of the present invention.

FIG. 5 is a piping diagram of a brake system according to a third embodiment of the present invention.

FIG. 6 is a piping diagram of a brake system according to a fourth embodiment of the present invention.

FIG. 7 is a piping diagram of a brake system according to a fifth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Brake system 3 Master cylinder 6 Brake actuator 8 Wheel cylinder 11 Main body 12 Cylinder hole 13 Piston 13a Engaged part 14 Screw mechanism 15 Drive shaft 17 Motor 30 Hydraulic chamber 35 Communication chamber 37 Shutoff mechanism 38 Valve opening member 61 Brake system 62 Brake actuator 63 Shutoff mechanism 65 Movable body 75 Brake system 76 Shutoff valve device 78 Branch passage 79 Check valve 82 Brake system 83 Double check valve 87 Brake system 88 Cylinder device 90 Stepped piston

Claims (10)

[Claims] 1. A master cylinder for generating a hydraulic pressure in response to a driver's operation, a wheel cylinder for generating a braking force by a hydraulic pressure from the master cylinder, and a wheel cylinder provided between the master cylinder and the wheel cylinder. A brake actuator that generates a hydraulic pressure in response to an external command and supplies the hydraulic pressure to a wheel cylinder, the brake actuator comprising: a main body having a cylinder hole; A piston which is slidably inserted into the cylinder bore and defines a hydraulic chamber communicating with the wheel cylinder and the master cylinder in a cylinder hole, and a rotational force of an external drive source which rotates in response to an instruction from the outside. And a screw mechanism for converting the movement into motion. Braking system provided with a blocking mechanism for blocking the flow of hydraulic fluid toward the hydraulic pressure chamber from the master cylinder in response to movement. 2. The shut-off mechanism prevents a flow of hydraulic fluid from the master cylinder to the hydraulic chamber by moving the piston from a non-operating position in a direction to reduce the volume of the hydraulic chamber. The brake system according to claim 1. 3. A valve seat provided on an outer periphery of the piston for communicating with the master cylinder and the hydraulic chamber, wherein the shut-off mechanism is provided in a passage connecting the master cylinder and the communication chamber. A valve body that can be attached to and detached from the valve seat, and the valve body is configured to be connected to the engaged portion formed on the outer periphery of the piston when the piston is at the inoperative position. The brake system according to claim 2, further comprising a valve opening member that is separated from a seat. 4. A master cylinder for generating a hydraulic pressure in accordance with a driver's operation, a wheel cylinder for generating a braking force by the hydraulic pressure from the master cylinder, and a wheel cylinder provided between the master cylinder and the wheel cylinder. A brake actuator that generates a hydraulic pressure in response to an external command and supplies the hydraulic pressure to a wheel cylinder, the brake actuator comprising: a main body having a cylinder hole; A piston which is slidably inserted into the cylinder bore and defines a hydraulic chamber communicating with the wheel cylinder and the master cylinder in a cylinder hole, and a rotational force of an external drive source which rotates in response to an instruction from the outside. A brake system having a screw mechanism for converting to motion, wherein the motion is generated by the master cylinder. Liquid when the pressure exceeds a predetermined pressure, the braking system provided with a blocking mechanism for blocking the flow of hydraulic fluid from the master cylinder toward the brake actuator that. 5. The shut-off mechanism is provided between the master cylinder and the brake actuator, and has one end receiving hydraulic pressure from the master cylinder and the other end resisting hydraulic pressure from the master cylinder. The brake system according to claim 4, further comprising a movable body that receives a predetermined urging force, and a valve device that closes when the movable body moves against the urging force. 6. A master cylinder for generating a hydraulic pressure in response to a driver's operation, a wheel cylinder for generating a braking force by the hydraulic pressure from the master cylinder, and a pipe connecting the master cylinder and the wheel cylinder. A brake actuator that is connected to the road via a branch path, generates a hydraulic pressure in response to an external command, and supplies the hydraulic pressure to the wheel cylinder, wherein the brake actuator forms a cylinder hole. A main body, a piston slidably inserted into the cylinder hole and defining a hydraulic chamber communicating with the wheel cylinder and the master cylinder in the cylinder hole, and an external drive source that rotates in response to the command from the outside A screw mechanism for converting the rotational force of the piston into a linear motion of the piston, Braking system provided with a check valve to the direction at the crossroads extending from the brake actuator to said wheel cylinder in a forward direction. 7. The check valve is a double check valve, a first input of the double check valve is connected to the brake actuator, a second input is connected to the master cylinder, and an output is connected to the master cylinder. The brake system according to claim 6, wherein the brake system is connected to the wheel cylinder. 8. The master cylinder is connected to the master cylinder from the wheel cylinder side based on an external signal transmitted in response to a stop of the vehicle, to a master cylinder side of the branch path of a pipe connecting the master cylinder and the wheel cylinder. The brake system according to claim 6, further comprising a shut-off valve for preventing a flow of the hydraulic fluid toward the cylinder. 9. A master cylinder for generating a hydraulic pressure in response to a driver's operation, a wheel cylinder for generating a braking force by the hydraulic pressure from the master cylinder, and a pipe connecting the master cylinder and the wheel cylinder. A brake actuator that is connected to the road via a branch path, generates a hydraulic pressure in response to an external command, and supplies the hydraulic pressure to the wheel cylinder, wherein the brake actuator forms a cylinder hole. A main body, a piston slidably inserted into the cylinder hole and defining a hydraulic chamber communicating with the wheel cylinder and the master cylinder in the cylinder hole, and an external drive source that rotates in response to the command from the outside A screw mechanism for converting the rotational force of the piston into a linear motion of the piston, At the crossroads, the small-diameter side receives the wheel cylinder-side hydraulic pressure, the large-diameter side receives the brake actuator-side pressure, and is movable in accordance with the acting force acting on the small-diameter side and the large-diameter side. A brake system comprising a cylinder device having a stepped piston. 10. The master cylinder is connected to the master cylinder from the wheel cylinder side based on an external signal transmitted in response to a stop of the vehicle, to a master cylinder side of a branch line of a pipe connecting the master cylinder and the wheel cylinder. The brake system according to claim 9, further comprising a shut-off valve configured to block a flow of the hydraulic fluid toward the cylinder.