JPS625964Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a vehicle braking system equipped with two mutually independent piping systems, which appropriately controls the braking fluid pressure supplied to the rear wheel cylinder that performs braking on the rear wheels of the vehicle. This invention relates to improvements in controlling devices.

Vehicle braking systems consist of two independent piping systems for the purpose of improving safety, and the brake fluid pressure generated in the master cylinder must be maintained at a predetermined value in order to obtain effective and safe braking. In many cases, the brake fluid pressure supplied to the rear wheel cylinders is configured to be lower than the brake fluid pressure supplied to the front wheel cylinders. One type of such device is a hydraulic pressure control valve inserted in one piping system to reduce the brake fluid pressure supplied from the master cylinder to one rear wheel cylinder, and a hydraulic control valve inserted in the other piping system to reduce the brake fluid pressure supplied from the master cylinder to one rear wheel cylinder. a balance piston that opens and closes the opening/closing valve based on a pressure difference between the braking fluid pressure supplied to the one rear wheel cylinder and the working fluid pressure supplied to the other rear wheel cylinder; A two-system control control device for a vehicle is provided that includes a balance valve that controls the brake fluid pressure supplied to the cylinder to be substantially equal to the brake fluid pressure supplied to the one rear wheel cylinder.

However, such devices require that the braking fluid pressure determined by a single hydraulic control valve inserted in one piping system is applied not only to the rear wheel cylinders of one piping system, but also to the rear wheel cylinders of the other piping system. It is also supplied to the rear wheel cylinders in the piping system, ensuring that the braking force between the left and right rear wheels does not vary, but there was still room for improvement.

This is because if a failure such as damage occurs in one of the piping systems, the braking fluid pressure in the one rear wheel cylinder will drop, so the balance piston will operate to close the on-off valve, allowing normal operation. The brake fluid pressure that should be supplied to the other rear wheel cylinder connected to the other piping system is unnecessarily cut off. Therefore, in such a case, the vehicle would be braked by only one wheel, resulting in a significant lack of braking force and the inherent disadvantage that stability during braking would be impaired.

In addition, if a failure occurs in the other piping system, the brake fluid pressure reduced by the hydraulic pressure control valve will be applied to the rear wheel cylinder connected to the one piping system, as in normal conditions. As a result, there was an inconvenience that the braking force of the rear wheel of the two wheels that performs the braking operation was insufficient.

The present invention was developed against the background of the above circumstances, and its purpose is to control the braking fluid pressure determined by the hydraulic pressure control valve installed in one piping system when it is connected to the other piping system. Even if one of the two piping systems breaks down, the brake fluid is supplied to the rear wheel cylinder connected to the other normal piping system, and the brake fluid is supplied to the rear wheel cylinder connected to the other normal piping system. An object of the present invention is to provide a hydraulic pressure control device for a two-system control system for a vehicle that supplies pressure.

In order to achieve such an objective, the hydraulic pressure control device of the present invention reduces pressure by a hydraulic pressure control valve provided in one piping system and supplies braking hydraulic pressure to one rear wheel cylinder, and the other brake hydraulic pressure. The balance piston, which operates based on the pressure difference between the brake fluid pressure supplied to the other rear wheel cylinder connected to the piping system, opens and closes the on-off valve provided in the other piping system. In a hydraulic pressure control device in a two-system control system for a vehicle that controls the brake fluid pressure supplied to one rear wheel cylinder to be equal to the brake fluid pressure supplied to the one rear wheel cylinder, (1) the above-mentioned a large diameter portion facing one end of the balance piston at an interval greater than the amount of movement required for the control operation of the balance piston that controls the brake fluid pressure supplied to the other rear wheel cylinder; and a side of the large diameter portion. (2) a stepped piston having a small diameter portion having a second pressure receiving surface having a smaller area than the first pressure receiving surface on the opposite side of the first pressure receiving surface; The small diameter portion of the piston is slidably fitted into the piston, and the piston contacts the step portion formed between the small diameter portion and the large diameter portion, and the first pressure receiving surface along with the second pressure receiving surface of the small diameter portion.
an annular piston having a third pressure receiving surface that constitutes a larger pressure receiving surface than the pressure receiving surface; (3) a stopper that prevents the annular piston from moving toward the balance piston; (4) one rear a first hydraulic chamber that is connected to a wheel cylinder and causes braking hydraulic pressure of the rear wheel cylinder reduced in pressure by the hydraulic pressure control valve to act on the first pressure receiving surface; (5) the other rear wheel cylinder; (6) a second hydraulic pressure chamber connected to a master cylinder that supplies brake fluid pressure to the master cylinder and causes brake fluid pressure of the master cylinder to act on the second pressure receiving surface and the third pressure receiving surface; (6) the one rear wheel cylinder; communicates with a master cylinder that supplies braking hydraulic pressure to the cylinder, and opens toward the outer circumferential surface of the large diameter portion of the stepped piston, when the stepped piston is moved together with the annular piston toward the small diameter portion thereof; A passageway communicating with the first hydraulic pressure chamber to transmit the braking hydraulic pressure of the master cylinder to the first hydraulic pressure chamber is provided.

In this way, when the two-system control device is normal, the stepped piston does not move, so the balance piston is allowed to operate, and the braking fluid pressure determined by the fluid pressure control valve is controlled. is supplied to both rear wheel cylinders that have different piping systems, and if one of the piping systems breaks down, the stepped piston moves to its larger diameter side and prevents the balance piston from operating. Therefore, the high brake fluid pressure of the master cylinder of that system is directly supplied to the rear wheel cylinder of the other normal piping system through the on-off valve, and furthermore,
If the other piping system fails, the stepped piston is moved together with the annular piston to its smaller diameter side, so the rear wheel cylinder of the normal piping system is affected by the high braking force of the master cylinder of that system. Hydraulic pressure is directly supplied through the passage.

Hereinafter, an embodiment of the present invention will be described in detail based on the drawings.

In FIG. 1, the master cylinder 2 is equipped with two pressure chambers 6 and 8 in which equal braking fluid pressure is generated in accordance with the operation of the brake pedal 4. Braking fluid pressure is supplied to the wheel cylinders that brake each wheel through two independent piping systems that mutually form an X-shape. That is, the pressure chamber 6 is connected to the front wheel cylinder 10 of the right front wheel, and
It is connected to the rear wheel cylinder 14 of the left rear wheel via a hydraulic pressure control valve 12, and the pressure chamber 8 is connected to the front wheel cylinder 16 of the left front wheel, and is also connected to the input of a balance valve 18, which is a hydraulic pressure control device. It is connected to a rear wheel cylinder 24 of the right rear wheel via a port 20 and an output port 22.
In addition, when the brake fluid pressure generated in the master cylinder 2 exceeds a predetermined value, the hydraulic pressure control valve 12 reduces the brake fluid pressure to a predetermined constant rate or a constant value and controls the brake fluid pressure to the rear. The valve is supplied to the wheel cylinder 14, and a proportioning (P) valve, a limit (L) valve, a G valve, etc. are known. Also, wheel cylinders 10, 14, 1
Reference numerals 6 and 24 actuate disc-type, drum-type, or other brake mechanisms to suppress the rotation of the corresponding wheels.

The balance valve 18 includes an on-off valve section 28 provided at one end of the housing 26, and a control section 34 including a balance piston 30 and a stepped piston 32 for controlling the on-off valve section 28.

That is, a cylinder bore 36 is formed in the center of the housing 26, a balance piston 30 is slidably fitted into the cylinder bore 36, and an output chamber 38 and a first hydraulic pressure chamber 40 are formed at both ends thereof. A through hole 44 is formed in the partition wall 42 facing the end surface of the balance piston 30 on the output chamber 38 side, and the valve chamber 46 communicating with the input port 20 is connected to the output chamber 38 communicating with the output port 22 through the through hole 44.
communicated through. And the valve chamber 46
A spherical valve 50 biased toward the through hole 44 by a spring 48 is housed in the spherical valve 50 , and the spherical valve 50 passes through the through hole 44 and connects to the balance piston 30 .
It is brought into contact with the tip of an operating shaft 52 which is protruded from the end surface of. Therefore, the balance piston 30
The spherical valve 50 opens and closes the space between the input port 20 and the output port 22 depending on the position of movement of the spherical valve 50 , and the through hole 44 , the spring 48 , and the spherical valve 50 form the opening/closing valve section 28 . Even when the on-off valve section 28 is in the closed state, it is also a check valve that allows the brake fluid to flow back to the input port 20 side when the pressure on the output port 22 side is high. In addition, 54 is a plug, which is screwed into the housing 26 and is inserted into the valve chamber 4.
6 is formed liquid-tight and also serves as a spring receiver for the spring 48.

The housing 26 is bored with a medium diameter bore 56 having a larger diameter than the cylinder bore 36 and a large diameter bore 58 having a larger diameter than the middle diameter bore 56 following the cylinder bore 36. The stepped piston 32 includes a large diameter portion 64 that is slidably fitted to the large diameter bore 58 of the piston 62, and a small diameter portion 66 that is slidably fitted to the through hole 60. The end face of the large diameter portion 64 is opposed to the end face of the balance piston 30, and the interval A is larger than the amount of movement necessary for the control operation of the balance piston 30, that is, the amount of movement in the axial direction for opening and closing the on-off valve portion 28. They are placed separately. Therefore, the first hydraulic chamber 40 is connected to the balance piston 3.
0 and the end surface of the large diameter portion 64 of the stepped piston 32, and its first hydraulic pressure chamber 40 communicates with a low pressure port 70 connected to the hydraulic pressure control valve 12 and the rear wheel cylinder 14. The braking fluid pressure is supplied to the rear wheel cylinder 14.

A plug 74 having a high pressure port 72 connected to the pressure chamber 8 is screwed into the opening of the large diameter bore 58, and a second hydraulic pressure chamber 76 communicating with the pressure chamber 8 is fluid-tightly formed. ing. For this reason, the end surface of the large diameter portion 64 of the stepped piston 32 connects the first pressure receiving surface 78, which receives the braking hydraulic pressure of the first hydraulic pressure chamber 40, to the small diameter portion 64 of the stepped piston 32.
The end face of the first
A second pressure receiving surface 80 having a smaller area than the pressure receiving surface 78 is formed, and the end surface of the annular piston 62 on the second hydraulic pressure chamber 76 side forms a pressure receiving surface having a larger area than the first pressure receiving surface 78 together with the second pressure receiving surface 80. A third pressure receiving surface 82 is formed.

Therefore, the stepped piston 32 is connected to the first hydraulic pressure chamber 4
According to the conditions of the braking hydraulic pressure in the zero and second hydraulic pressure chambers 76, the operation is performed as follows. That is, the annular piston 62 is brought into contact with a stopper 84 which is a step between the medium diameter bore 56 and the large diameter bore 58, and the small diameter part 66 of the stepped piston 32 is in contact with the through hole 60 of the stopper 84. Since the small-diameter portion 66 and the large-diameter portion 64 are fitted until they come into contact with each other, the first pressure-receiving surface 7
When the force acting on the second pressure receiving surface 80 is smaller than the force acting on the second pressure receiving surface 80 mainly based on the braking hydraulic pressure in the second hydraulic pressure chamber 76, the stepped piston 32 moves toward the large diameter portion 64, and When the force acting on the first pressure receiving surface 78 is larger than the force acting on the second pressure receiving surface 80 and the third pressure receiving surface 82, the stepped piston 32 moves toward the small diameter portion 66 and acts on the first pressure receiving surface 78. The force is applied to the second pressure receiving surface 8
0 and the second pressure receiving surface 80
When the force acting on the third pressure receiving surface 82 is smaller than the force acting on the third pressure receiving surface 82, the stepped piston 32 is at rest.

A disc spring 86 is inserted between the annular piston 62 and the plug 74, and is biased so that the annular piston 62 always comes into contact with the stopper 84. A compression coil spring 90 is inserted between the bottom surface of the bottom hole 88 and the end surface of the balance piston 30, and is always biased in a direction to separate the balance piston 30 and the stepped piston 32. The disc spring 86 and the compression coil spring 90 are mainly used for the balance valve 1.
8, the positions of the stepped piston 32 and the annular piston 62 are maintained when they are not in operation. Further, 92 is an oil seal.

Two O-rings 94 and 96 are arranged in parallel on the outer periphery of the large diameter portion 64 of the stepped piston 32.
The passage 100 communicating with the high pressure port 98 is slightly connected to the O ring 94 from the O ring 94 on the first pressure receiving surface 78 side.
It opens into a medium diameter bore 56 in a laterally facing position. Therefore, the portion where the passage 100 opens into the medium diameter bore 56 is always fluid-tightly closed by the O-rings 94 and 96, but when the stepped piston 32 moves toward the small-diameter portion 66, the O-ring closes. 94 passes through the open portion of the passageway 100 in the medium diameter bore 56 so that the high pressure port 98 communicates with the first hydraulic chamber 40 through the passageway 100. That is, the high pressure port 98 is connected to the pressure chamber 6, and the large diameter portion 64 of the stepped piston 32 and the O-ring transfer the high braking hydraulic pressure of the pressure chamber 6 to the rear wheel cylinder through the passage 100 and the first hydraulic pressure chamber 40. 14 is formed.

As described above, the bypass valve has a very simple structure, has a small number of parts, is inexpensive, and is completely free from failures such as twisting.

The operation of this embodiment will be explained below.

When the brake pedal 4 is not operated, no brake fluid pressure is generated in the master cylinder 2. Therefore, according to the biasing force of the compression coil spring 90, the balance piston 30 is moved toward the opening/closing valve section 28, and the spherical valve 50 is pushed up by the operating shaft 52 against the biasing force of the spring 48, thereby inputting input. The space between the port 20 and the output port 22 is opened, and the stepped piston 32 is moved toward the small diameter portion 66 until it comes into contact with the annular piston 62, and the end surface of the balance piston 30 and the stepped piston 32
A gap A is formed between the end face on the large diameter portion 64 side. FIG. 1 shows this state.

In this state, when the brake pedal 4 is operated, the braking hydraulic pressure generated in the pressure chamber 6 is supplied to the rear wheel cylinder 14 via the front wheel cylinder 10 and the hydraulic pressure control valve 12, and is also supplied to the pressure chamber 8. The generated braking fluid pressure is supplied to the rear wheel cylinder 24 via the front wheel cylinder 16, input port 20, and output port 22, and the braking effect of each wheel begins to appear.

When the brake fluid pressure is increased and exceeds a predetermined constant value, the pressure reduction action of the fluid pressure control valve 12 is performed, so that the brake pressure is lower than the brake fluid pressure generated in the pressure chamber 6. Hydraulic pressure is supplied to the rear wheel cylinder 14 and the low pressure port 70 of the balance valve 18. On the other hand, since the braking fluid pressure generated in the pressure chamber 8 is directly supplied to the output chamber 38, the output chamber 38
8 and the first hydraulic chamber 40, and the balance piston 30 is moved to the first hydraulic chamber 40 at a low pressure.
It is moved to the side against the biasing force of the compression coil spring 90. As a result, the spherical valve 50
4 is closed, the pressure in the output chamber 38 is prevented from increasing. However, when the pressure in the first hydraulic pressure chamber 40 increases and the pressure becomes higher than the pressure in the output chamber 38, the balance piston 30 moves toward the output chamber 38. The spherical valve 50 is pushed up and the through hole 44 is opened again. By repeating the operation of the balance piston 30 in this manner, the input port 20 is removed from the pressure chamber 8.
The brake fluid pressure supplied to the rear wheel cylinder 24 is controlled to be equal to the output pressure of the fluid pressure control valve 12 supplied to the low pressure port 70, and
is supplied to

In other words, of the two piping systems, pressure chamber 6
The hydraulic pressure determined by the single hydraulic pressure control valve 12 inserted in one piping system that transmits the braking fluid pressure of It is also supplied to the rear wheel cylinder 24 which has a different piping system.

As a result, the braking force on the rear wheels is lower than that on the front wheels, preventing the wheels from locking up (the wheels stopping and slipping against the road surface) and providing effective and safe braking effects. .

In the above operating state, the first hydraulic chamber 4
The brake fluid pressure reduced by the hydraulic pressure control valve 12 is supplied to the first hydraulic pressure chamber 70, and the high brake fluid pressure of the pressure chamber 8 is supplied to the second hydraulic pressure chamber 76.
A pressure difference occurs between both ends of the stepped piston 32.
The pressure receiving surfaces 78, 80, and 83 are arranged so that the force acting on the first pressure receiving surface 78 is greater than the force acting on the second pressure receiving surface 80 and is smaller than the force acting on the second pressure receiving surface 80 and the third pressure receiving surface 82.
The area of 82 has been determined.

Next, the operation when one system fails will be explained.

First, if the piping system that transmits the brake fluid pressure in the pressure chamber 8 is damaged, brake fluid pressure will not be generated in the pressure chamber 8, and the brake fluid will only be in the pressure chamber 6 when the brake pedal 4 is operated. Pressure is generated. Therefore, only the braking fluid pressure in the pressure chamber 6 is transmitted through the remaining normal piping system, and is transmitted to the rear wheel cylinder 1 via the front wheel cylinder 10 and the fluid pressure control valve 12.
4 and the high pressure port 98 of the balance valve 18. As a result, the pressure in the second hydraulic chamber 76 decreases abnormally compared to the pressure in the first hydraulic chamber 40.
The force acting on the first pressure receiving surface 78 becomes larger than the force acting on the second pressure receiving surface 80 and the third pressure receiving surface 82, and the stepped piston 32, together with the annular piston 62, resists the biasing force of the disc spring 86. Move to the small diameter portion 66 side. Accordingly, the O-ring 94 passes through the opening of the passageway 100 in the medium diameter bore 56 so that the high pressure port 98 communicates with the first hydraulic chamber 40 through the passageway 100. And this high pressure port 9
8 and the first hydraulic pressure chamber 40, the pressure chamber 6
Since the high brake hydraulic pressure is directly supplied to the rear wheel cylinder 14 via the high pressure port 98 and the first hydraulic pressure chamber 40, the brake hydraulic pressure of the rear wheel cylinder 14 is increased compared to the normal state. In other words, the vehicle is braked by the right front wheel and the left rear wheel among all wheels, and the braking force of the left rear wheel is higher than normal, so even when one system fails, it is stable. It is possible to obtain a certain braking effect.

Next, if the piping system that transmits the brake fluid pressure in the pressure chamber 6 is damaged, brake fluid pressure will not be generated in the pressure chamber 6, and the brake will be applied only to the pressure chamber 8 when the brake pedal 4 is operated. Hydraulic pressure is generated. Therefore, only the braking fluid pressure in the pressure chamber 8 is supplied to the front wheel cylinder 16, the input port 20 of the balance valve 18, and the high pressure port 72 through the remaining normal piping system. As a result, the pressure in the first hydraulic chamber 40 decreases abnormally compared to the pressure in the output chamber 38, so the balance piston 30 moves the pressure in the first hydraulic chamber 40 according to the pressure difference between those chambers 38, 40. Although receiving a driving force toward the side, the first hydraulic pressure chamber 4 also receives a driving force toward the second hydraulic pressure chamber 76.
Since the pressure at 0 is significantly lower, the force acting on the first pressure receiving surface 78 is smaller than the force acting on the second pressure receiving surface 80, and the stepped piston 32 resists the biasing force of the compression coil spring 90. It moves toward the large diameter portion 64 until it comes into contact with the end face of the balance piston 30, thereby preventing the balance piston 30 from moving. Here, the pressures in the output chamber 38 and the second hydraulic pressure chamber 76 become equal, but the force acting on the second pressure receiving surface 80 is due to the pressure difference between the output chamber 38 and the first hydraulic pressure chamber 40 The pressure receiving area of the second pressure receiving surface 80 is set to be larger than the end surface of the balance piston 30 so as to exceed the driving force acting on the balance piston 30 due to the force. Therefore, since the spherical valve 50 is maintained in a pushed up state by the operating shaft 52, the high braking fluid pressure in the pressure chamber 8 supplied to the input port 20 is applied to the valve chamber 46, the through hole 44, and the output port. 22 directly to the rear wheel cylinder 24.
The brake fluid pressure is increased compared to normal. In other words, the vehicle is braked by the left front wheel and right rear wheel among all wheels, and the braking force of the right rear wheel is made higher than normal, so that it is stable even in the event of a failure in one system. It is possible to obtain a braking effect of

In this state, the opening of the passage 100 in the medium-diameter bore 56 is located between the O-rings 94 and 96, so the high-pressure port 98 and the first hydraulic chamber 40 are blocked.

As described above, according to this embodiment, during normal operation, the braking fluid pressure determined by the single fluid pressure control valve 12 is supplied to the rear wheel cylinders 14 and 24 having different piping systems, and the pressure chamber If a failure occurs in the piping system that transmits the braking fluid pressure of 6, the stepped piston 32
side and prevents movement of the balance piston 30, the pressure chamber 8 is connected to the rear wheel cylinder 24 of the other normal piping system via the on-off valve section 28.
If a high brake fluid pressure is supplied and a failure occurs in the piping system to which the brake fluid pressure in the pressure chamber 8 is transmitted, the stepped piston 32 moves together with the annular piston 62 toward its small diameter portion 66. By opening the passage 100 in the medium diameter bore 56, the high brake fluid pressure in the pressure chamber 6 is supplied directly through the passage 100 to the rear wheel cylinder 14 of the other normal piping system.

Although one embodiment of the present invention has been described above based on the drawings, the present invention may be applied to other aspects as well.

For example, in the above-described embodiment, when the piping system that transmits the brake fluid pressure in the pressure chamber 6 fails, the balance piston 3
The second pressure receiving surface 80 of the stepped piston 32 is
Although the pressure receiving area of the balance piston 30 is made larger, the pressure receiving area of the end surface of the balance piston 30 may be made larger than the second pressure receiving surface and the opening/closing valve section 28 may be operated.

The above-mentioned embodiment is merely one embodiment of the present invention, and various modifications may be made to the present invention without departing from the spirit thereof.

As described in detail above, according to the hydraulic pressure control device in the two-system control system of the present invention, the braking hydraulic pressure determined by the hydraulic pressure control valve provided in one piping system is applied to the rear wheel of that piping system. Supply is supplied not only to the cylinder but also to the rear wheel cylinder connected to the other piping system, and even if one of the two piping systems breaks down, the rear wheel cylinder is connected to the other normal piping system. A higher brake fluid pressure than normal is supplied to the rear wheel cylinder, increasing the braking force of the rear wheel to which the rear wheel cylinder is attached.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the configuration of a two-system control device including an embodiment of the present invention. 2...Master cylinder, 12...Liquid pressure control valve,
14, 24...Rear wheel cylinder, 28...
On-off valve section (on-off valve), 40...first hydraulic pressure chamber, 60
...Through hole, 62...Annular piston, 64...Large diameter portion, 66...Small diameter portion, 76...Second hydraulic chamber, 7
8...First pressure receiving surface, 80...Second pressure receiving surface, 82...
...Third pressure receiving surface, 84... Stopper, 100... Passage, A... Interval.

Claims (1)

[Claims for Utility Model Registration] Braking fluid pressure is reduced by a hydraulic pressure control valve installed in one piping system and supplied to one rear wheel cylinder, and brake fluid pressure is supplied to one rear wheel cylinder connected to the other piping system. A balance piston that operates based on the pressure difference between the brake fluid pressure supplied to the wheel cylinder and the other rear wheel cylinder opens and closes an on-off valve provided in the other piping system, thereby providing braking to the other rear wheel cylinder. In a hydraulic pressure control device in a two-system control system for a vehicle that controls hydraulic pressure to be equal to the braking hydraulic pressure supplied to the one rear wheel cylinder, the braking hydraulic pressure supplied to the other rear wheel cylinder. a large diameter portion facing one end of the balance piston at an interval greater than the amount of movement required for the control operation of the balance piston, and a first pressure receiving surface on the opposite side of the first pressure receiving surface on the side of the large diameter portion. a stepped piston having a small diameter portion having a second pressure receiving surface having a smaller area than the pressure receiving surface; and a through hole, the small diameter portion of the stepped piston is slidably fitted into the through hole, and the small diameter portion of the stepped piston is slidably fitted into the through hole; and the large-diameter portion, and includes a third pressure-receiving surface that is larger than the first pressure-receiving surface together with the second pressure-receiving surface of the small-diameter portion. a piston; a stopper that prevents the annular piston from moving toward the balance piston; connected to the one rear wheel cylinder;
a first hydraulic chamber that applies braking hydraulic pressure of the rear wheel cylinder whose pressure has been reduced by the hydraulic pressure control valve to the first pressure receiving surface; and a master cylinder that supplies braking hydraulic pressure to the other rear wheel cylinder. a second hydraulic pressure chamber that is connected to and applies braking hydraulic pressure of the master cylinder to the second pressure receiving surface and the third pressure receiving surface, and communicates with the master cylinder that supplies braking hydraulic pressure to the one rear wheel cylinder. and opens toward the outer circumferential surface of the large diameter portion of the stepped piston,
a passage that communicates with the first hydraulic pressure chamber to transmit the braking hydraulic pressure of the master cylinder to the first hydraulic pressure chamber when the stepped piston is moved together with the annular piston toward its small diameter side; A hydraulic pressure control device in a two-system control control device for a vehicle, characterized in that it is provided with the following.