JP2002331924A - Hydraulic brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost hydraulic brake device dispensing with tuning of a pressure regulating means. SOLUTION: A pressure damper chamber R4 is provided in a power piston 30 between a spool 14 and a reaction disc 41. The pressure damper chamber R4 is connected to a reservoir 7 via a check valve 60 allowing the passing of brake liquid from the pressure damper chamber R4 to the reservoir 7 and an orifice 61b provided in parallel to the cheek valve 60.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic brake device for supplying brake hydraulic pressure to a wheel cylinder of a vehicle wheel, and more particularly to a hydraulic brake device having an auxiliary hydraulic pressure source and a pressure adjusting means in addition to a master cylinder. About.

[0002]

2. Description of the Related Art A master cylinder for driving a master piston forward in response to operation of at least a brake operating member to increase brake fluid in a reservoir and output brake fluid pressure;
A power piston arranged behind the master piston to form a power chamber, an auxiliary hydraulic pressure source that boosts the brake fluid in the reservoir to a predetermined pressure and outputs hydraulic pressure, and is connected to the auxiliary hydraulic pressure source and connected to the reservoir. A pressure adjusting means for adjusting the output hydraulic pressure of the auxiliary hydraulic pressure source to a predetermined pressure and supplying the same to the power chamber; 2. Description of the Related Art A hydraulic brake device including a piston and a reaction disk that transmits the pressure to a pressure adjusting unit is known.

[0003]

In the above-mentioned conventional hydraulic brake apparatus, the controllability of gently operating the brake pedal to finely control the brake hydraulic pressure and the rapid operation of the brake pedal to rapidly increase the brake hydraulic pressure. High responsiveness that can be achieved is required, and both tuning and controllability are achieved by tuning the pressure adjusting means. However, since the tuning of the pressure adjusting means is different for each vehicle type, it is necessary to prepare a plurality of pressure adjusting means, and there is a problem that the cost of the hydraulic brake device increases.

An object of the present invention is to provide a low-cost hydraulic brake device which does not require tuning of the pressure adjusting means.

[0005]

In order to solve the above-mentioned technical problem, as set forth in claim 1, a master piston is driven forward at least in response to operation of a brake operation member to increase the pressure of brake fluid in a reservoir. A master cylinder that outputs brake fluid pressure, a power piston that is arranged behind the master piston to form a power chamber, and an auxiliary hydraulic pressure source that boosts brake fluid in the reservoir to a predetermined pressure and outputs fluid pressure. And a pressure brake connected to the auxiliary hydraulic pressure source and connected to the reservoir, for adjusting the output hydraulic pressure of the auxiliary hydraulic pressure source to a predetermined pressure and supplying the output hydraulic pressure to the power chamber. In the apparatus, a pressure damper chamber is provided in front of the pressure adjusting means, and the pressure damper chamber is connected to the reservoir via an orifice. Key to configure devices.

According to the first aspect of the present invention, the pressure damper chamber is provided in front of the pressure adjusting means, and the pressure damper chamber is connected to the reservoir via the orifice. As a result, high controllability in which the brake fluid pressure can be finely controlled by slowly operating the brake pedal is ensured. In addition, high controllability is ensured without tuning the pressure adjusting means, so that a low-cost hydraulic brake device can be obtained.

Next, according to a second aspect of the present invention, a check valve is provided in parallel with the orifice to allow a brake fluid to flow from the pressure damper chamber to the reservoir. A pressure brake device is preferred.

According to the second aspect of the present invention, the pressure damper chamber is provided in front of the pressure adjusting means, and the pressure damper chamber is connected to the reservoir via the orifice. As a result, high controllability in which brake fluid pressure can be finely controlled by slowly operating the brake pedal is secured. Furthermore, when the brake pedal is suddenly operated and the pressure in the pressure damper chamber exceeds a predetermined pressure, the check valve is operated, the brake fluid is bypassed to the reservoir, and the operation of the pressure adjusting means is not hindered, so that high responsiveness is secured. You. In addition, high controllability and high responsiveness are ensured without tuning the pressure regulating means, so that a low-cost hydraulic brake device can be obtained.

Next, as set forth in claim 3, it is preferable that the pressure regulating means comprises a spool valve.

According to the third aspect of the present invention, the spool valve is constituted by using a spool capable of easily obtaining high accuracy, and the spool valve constitutes a pressure regulating means. Therefore, a low-cost pressure adjusting means can be obtained, and a low-cost hydraulic brake device can be obtained.

Next, a pressurizing chamber selectively connected to the auxiliary hydraulic pressure source or the reservoir is provided between the power piston and the spool valve. When the pressure chamber is connected to the hydraulic pressure source, the hydraulic brake device is characterized in that the spool valve is biased forward independently of the brake operating member.

According to the fourth aspect of the present invention, when the hydraulic pressure of the auxiliary hydraulic pressure source is supplied to the pressurizing chamber formed between the power piston and the spool valve, the spool valve moves with respect to the brake operating member. A predetermined hydraulic pressure is supplied to the power chamber, and the power piston and the master piston advance to generate brake hydraulic pressure. That is, it is possible to perform an automatic operation brake that generates a brake fluid pressure without a driver's brake operation.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described specifically with reference to embodiments. FIGS. 1 and 2 show a hydraulic brake device according to a first embodiment of the present invention, in which a pedaling force applied to a brake pedal 11 (brake operating member) is increased by a first force.
The brake operating force transmitted through the input rod 12 and the second input rod 13 as the brake operating force and assisted by the hydraulic assisting unit HB is used as the brake hydraulic pressure from the master cylinder MC through the ports 21 d and 21 e to the hydraulic pressure regulator. PR (for example, anti-lock brake system)
Wheel cylinders FL, F mounted on each wheel via
It is configured to be supplied to R, RL, and RR. FIG. 1 shows the overall configuration, and FIG. 2 shows the initial position (at rest).
The liquid pressure assisting portion HB of FIG. In the following description, the front indicates the left direction in FIGS. 1 to 3,
The rear means the right direction in FIGS.

As shown in FIG. 1, a body 21, a front cap 22 liquid-tightly fixed to the front opening of the body 21 by an O-ring S9 and a fixing ring 72,
A rear cap 24 fixed in a liquid-tight manner by an O-ring S5 and a fixing ring 71 to a rear opening of the body 21;
The cylinder housing is formed by the sleeve 23 inserted into the inner hole.

A rod stopper 25 is screwed and fixed to the rear cap 24 via a bellows S21. Rear cap 24, velose S21, rod stopper 25,
A drain chamber R8 is formed by the second input rod 13, a third piston 33 described later, and the seal cup S1. The drain chamber R8 includes a communication path 24a provided in the rear cap 24 and a communication path 21c formed in the body 21.
, And is always in communication with the reservoir 7.

A power piston 30 composed of a first piston 31, a second piston 32, a third piston 33, and a fourth piston is slidably and liquid-tightly inserted into the inner hole of the sleeve 23 via seal rings S11 and S12. It is inserted.

The first piston 31 is inserted into the inner hole of the body 21 in a liquid-tight and slidable manner via an O-ring S3, and the first piston 31, the O-ring S3, the inner hole of the body 21, A first hydraulic pressure chamber R1 is formed by the O-ring S4 and a master piston 36 described later.

The first hydraulic chamber R1 is connected to the first power chamber R3 via the port 21g, the first check valve C1, and the port 21i.
(Power chamber) and the reservoir 7 via the port 21a and the second check valve C2.
Further, the first hydraulic chamber R1 is connected to the rear wheel cylinders RL, R via the port 21d and the hydraulic regulator PR.
Connected to R. A fluid pressure sensor D2 is connected to a pipe between the port 21d and the fluid pressure regulator PR.

The second piston 32 includes a seal ring S1
1, the sleeve 23 is slidably and liquid-tight through S12.
The first power chamber R3 is formed between the rear end surface of the second piston 32 and the bottom of the front opening of the rear cap 24.

When the first piston 31 is press-fitted and fixed to the second piston 32, the third outwardly facing flange 33 a is connected to the first piston 3 via the fourth piston 34.
1 and is fixedly engaged with the inward flange. The third piston 33 is slidably and liquid-tightly fitted into the inner hole of the rear cap 24 via the seal cup S1.

In front of the power piston 30, a master piston 36 is slidably and liquid-tightly inserted into a front inner hole of the body 21 via a seal cup S 2 and an O-ring S 4. , The O-ring S4, the seal cup S2, the front inner hole of the body 21, the O-ring S9 and the front cap 22, form a second hydraulic chamber R2. A spring 52 is interposed between the master piston 36 and the front cap 22, and the master piston 3
6 is biased backward. A spring 51 is interposed between the master piston 36 and the first piston 31 to urge the power piston 30 rearward.

The second hydraulic chamber R2 is connected to the reservoir 7 via a piston port 36a and a port 21b provided on the master piston 36, and is connected to the port 21.
e and a fluid pressure regulator PR to the front wheel cylinders FL, FR.

In front of the second input rod 13, there is disposed a spool 14 which is slidably fitted into the inner hole of the fourth piston 34 and whose rear end abuts on the front spherical portion 13a of the second input rod 13. Has been established.

A first groove 14a and a second groove 14b are formed all around the outer peripheral surface of the spool 14. Spool edge 14a of first groove 14a
A spool valve is formed by the spool edge 14b1 of the first and second grooves 14b and the hole 34a. In the initial position shown in FIG.
a is in communication with the second groove 14b and the hole 34a.
Are in a non-communication state.

The first groove 14a is provided with the spool 1
4 and the communication groove 13b of the second input rod 13
Is always communicated with the drain chamber R8 through the
The groove 14b has an accumulator which constitutes the auxiliary hydraulic pressure source AS through the holes 34b and 32b, an annular passage between the outer peripheral surface 32a of the second piston 32 and the inner peripheral surface 23a of the sleeve 23, the hole 23b and the port 21f. Always connected to AC. The auxiliary hydraulic pressure source AS includes the accumulator AC, the hydraulic pump HP, the electric motor M that drives the hydraulic pump HP, and the hydraulic pressure sensor D1.

Further, the hole 34a is provided in the fourth piston 34 in the axial direction, and does not intersect with the hole 34b.
4c and through a hole 33b provided in the flange 33a of the third piston 33, it is always in communication with the first power chamber R3, and is always in communication with the port 21i from the first power chamber R3 through an annular passage R7. Have been.

A disk 61 having a hole 61a and an orifice 61b is formed in the opening of the front flange of the spool 14.
Is press-fitted, and a ball 63 is provided behind the opening of the disc 61.
And a spring 64. A check valve 60 that allows the brake fluid to flow from the front side to the rear side of the disk 61 by the hole 61a, the ball 63, and the spring 64.
Is formed. The spool 14 is provided with a spring 65
The rear end of the spool 14 is
It comes into contact with the front spherical portion 13a of the input rod 13.

A second power chamber R6 (pressurizing chamber) is formed between the rear end surface of the front flange of the spool 14 and the fourth piston 34. The second power chamber R6 has a hole 34.
d, through the communication passage R5 and the port 21h, and through the solenoid valves V1 and V2, the auxiliary hydraulic pressure source or the drain chamber R8.
Selectively connected to

The first opening of the first piston 31
A reaction disk 41 for transmitting a hydraulic reaction force due to the brake hydraulic pressure generated in the hydraulic chamber R1 and the second hydraulic chamber R2 to the first piston 31 and the spool 14 is inserted in a liquid-tight manner. First in front of reaction disk 41
A retainer 42 for seating the spring 51 is fitted into the front opening of the piston.

At the rear opening of the first piston 31, a force transmitting member 1 integrally formed with a resin cover 15 at the front is provided.
6 is inserted. First hydraulic chamber R1 and second hydraulic chamber R
When the brake fluid pressure is generated in the cylinder 2, the reaction disk 41 swells to the rear opening of the first piston, and the hydraulic reaction force due to the brake fluid pressure is transmitted to the spool 14 via the force transmitting member 16. is there.

A pressure damper chamber R4 is formed between the front flange of the spool 14 and the force transmitting member 16.
When the spool 14 moves forward and the volume of the pressure damper chamber R4 decreases, the brake fluid in the pressure damper chamber R4 drains through the orifice 61b, the inner hole 14c of the spool 14, and the communication groove 13b of the second input rod 13. It will flow out into the chamber R8 and the reservoir 7. Therefore, due to the viscous resistance when the brake fluid in the pressure damper chamber R4 passes through the orifice 61b and the elastic resistance due to the compression of the spring 65, a moderate resistance is applied to the forward movement of the spool 14, and the spool 14 Vibration and overstroke are prevented. In other words, tuning of the dimensions and shapes of the first groove 14a, the spool edge 14a1, the second groove 14b, the spool edge 14b1, and the hole 34a of the spool 14 for each vehicle type is not required to cause the spool 14 to vibrate or overstroke.

When the forward movement speed of the spool 14 is high and the hydraulic pressure in the pressure damper chamber R4 is higher than a predetermined pressure, the spring 6 set to a predetermined set load is set.
When the ball 4 is compressed, the ball 63 separates from the rear opening of the hole 61a, and a communication path larger than the passage area of the orifice 61b is formed. Therefore, the brake fluid in the pressure damper chamber R4 can flow out to the drain chamber R8 and the reservoir 7 without receiving a large viscous resistance. Therefore, even when the volume of the pressure damper chamber R4 decreases rapidly, the brake fluid in the pressure damper chamber R4 flows out smoothly to the drain chamber R8 side, so that the fast forward movement of the spool 14 is not hindered. That is, in order to prevent the fast forward movement of the spool 14 from being hindered, the first groove 14a, the spool edge 14a1, the second groove 14b, the spool edge 1
Tuning of the size and shape of the 4b1 and the hole 34a for each vehicle type is not required.

Next, the operation of the first embodiment of the present invention during normal brake operation will be described with reference to FIGS.

When the brake pedal 11 is depressed, the first input rod 12 and the second input rod 13 connected to the brake pedal 11 advance, and the spool 14 moves to the power piston 30 with the advance of the second input rod 13. Move forward relative to you.

When the spool 14 moves forward relative to the power piston 30, the first glue portion 1 of the spool 14
4a and the hole 34a are cut off, the spool edge 14b1 of the second glue portion 14b of the spool 14 overlaps with the hole 34a, and the second glue portion 14b
4a. Due to the communication between the second glue portion 14b and the hole 34a, the first power chamber R3 is connected to the hole 33b and the hole 34a.
c, hole 34a, second groove 14b, hole 32b, outer peripheral surface 32a of second piston 32 and inner peripheral surface 23 of sleeve 23
is connected to the accumulator AC through an annular passage between the accumulator AC, the hole 23b and the port 21f. As a result, the high-pressure brake fluid of a predetermined pressure stored in the accumulator AC is supplied to the first power chamber R3, and the power piston 30 is relatively assisted by the high-pressure brake fluid with respect to the body 21 and the sleeve 23. Advance.

At this time, the rear side of the first check valve C1 is communicated with the power chamber through the port 21i, and the first check valve C1
The front side of 1 is connected to the first hydraulic pressure chamber R1 via the port 21g, but the hydraulic pressure of the brake fluid stored in the accumulator AC is always higher than the hydraulic pressure generated in the first hydraulic pressure chamber R1. Is also set to be large, the first check valve C1 keeps the closed state. Further, the second check valve C2 inhibits the flow of the brake fluid from the first hydraulic pressure chamber R1 to the reservoir 7, so that the power piston 30 is power-assisted as described above and the body 21 and the sleeve 2
3, the brake fluid in the first hydraulic pressure chamber R1 is supplied to the rear wheel cylinders RL and RR via the port 21d and the hydraulic pressure regulator PR to increase the pressure, and the braking force is increased. appear.

At the same time, the forward force of the power piston 30 is
The master piston 36 is transmitted to the master piston 36 via the spring 51 and pressed forward, and the master piston 36 is pressed forward by the hydraulic pressure generated in the first hydraulic pressure chamber R1. As the master piston 36 advances, the piston port 36a is closed by the seal cup S2, and the brake fluid in the second hydraulic chamber R2 is supplied to the front wheel cylinders FL and FR via the port 21e and the hydraulic regulator PR. Pressure to generate braking force.

The retainer 42 and the reaction disk 41 are pressed rearward by the hydraulic reaction force generated by the brake hydraulic pressure generated in the first hydraulic chamber R1 and the second hydraulic chamber R2. The reaction disk 41 pressed rearward swells into the rear opening of the first piston 31, and the force transmitting member 1
6, the spool 14, the second input rod 13 and the first input rod 13.
The input rod 12 will be pushed back. At this time, the hydraulic reaction force received by the reaction disk 41 is a ratio (== the ratio of the pressure receiving area of the force transmitting member 16 to the pressure receiving area of the first piston 31 (the seal area sealed by the O-ring S3)).
1: i, i ≧ 1), so that the force is transmitted to the force transmitting member 16;
As if the pedal force was amplified i times, the power piston 3
It is output from 0. That is, the power piston 30, the first power chamber R3, and the auxiliary hydraulic pressure source AS form a hydraulic booster.

When the driver slightly increases the pedal depression force to slightly increase the braking force and, consequently, the vehicle deceleration during the normal brake operation, the spool 14
Moves forward with respect to the first piston 31, and the pressure damper chamber R4
Volume is reduced. When the spool 14 moves forward and the volume of the pressure damper chamber R4 decreases, the brake fluid in the pressure damper chamber R4 discharges into the orifice 61b and the inner hole 14 of the spool 14.
The fluid flows out to the drain chamber R8 and the reservoir 7 via the communication groove 13b of the second input rod 13 and the communication rod 13c. That is, the brake fluid in the pressure damper chamber R4 is
1b and an elastic resistance due to the compression of the spring 65, an appropriate resistance is applied to the forward movement of the spool 14, and the vibration and the overstroke of the spool 14 are prevented. The output of the pressure booster can be precisely controlled.

In the normal braking operation described above, when the driver rapidly increases the pedal depression force to rapidly increase the braking force and thus the vehicle deceleration, that is, the forward movement speed of the spool 14 is high and the pressure damper chamber When the hydraulic pressure in R4 becomes larger than the predetermined pressure, the spring 63 set to the predetermined set load is compressed, so that the ball 63 separates from the rear opening of the hole 61a, and the passage area of the orifice 61b is increased. A larger communication path is formed. For this reason, the brake fluid in the pressure damper chamber R4 does not receive a large viscous resistance and the drain fluid R
8 and the reservoir 7. That is, even when the volume of the pressure damper chamber R4 decreases rapidly, the brake fluid in the pressure damper chamber R4 flows out smoothly to the drain chamber R8 side, so that the fast forward movement of the spool 14 is not hindered. The high output responsiveness of the above-described hydraulic booster is maintained.

Next, the operation of the first embodiment of the present invention at the time of automatic operation braking will be described.

During automatic operation braking, the solenoid valve V1 is closed and the solenoid valve V2 is opened. Further, since the brake pedal 11 is not depressed, the second groove 14b of the spool 14 is blocked from the hole 34a, and the accumulator AC and the first power chamber R3 are in a non-communication state.

On the other hand, the accumulator AC has a solenoid valve V
2. Since the hydraulic pressure is supplied to the second power chamber R6 through the port 21h, the communication path R5, and the hole 34d, the spool 14 is generated by the spring force of the spring 65 and the orifice 61b. Move forward against viscous drag. Then, the second groove 14b of the spool 14 communicates with the hole 34a, and the accumulator AC and the first power chamber R3 communicate. And the accumulator AC
The high pressure brake fluid of a predetermined pressure stored in the first power chamber R
3, the power piston 30 is advanced relatively to the body 21 and the sleeve 23 in a form of being assisted by the high-pressure brake fluid, but the subsequent operation is the same as that of the normal brake operation. Is omitted.

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

In FIG. 3, the same or equivalent members and portions as those in FIGS. 1 and 2 are denoted by the same reference numerals as those in FIGS. 1 and 2, and duplicate description will be omitted.

In the second embodiment, the spool 114
A first force transmitting member 116 having an orifice 162 formed therein is fitted into the opening of the front flange, and a seal cup 163 for sealing between the opening of the front flange and the first force transmitting member 116 is attached. Have been. The seal cup 163 prohibits the flow of brake fluid from the rear side to the front side of the seal cup 163, but the seal cup 1
When the pressure on the front side of 63 becomes equal to or higher than the predetermined pressure, the flow of the brake fluid from the front side to the rear side of seal cup 163 is permitted. That is, the seal cup 163 is connected to the check valve 1
60 are configured.

The first force transmitting member 116 and the spool 114 are urged rearward by a spring 165,
The rear end of the spool 114 is in contact with the front spherical portion 13a of the second input rod 13.

A second force transmitting member 216 integrally formed with the resin cover 15 is inserted into the rear opening of the first piston 31 between the first input transmitting member 116 and the reaction disk 41. I have. First hydraulic chamber R1 and second hydraulic chamber R1
When the brake fluid pressure is generated in the fluid pressure chamber R2, the reaction disk 41 swells to the rear opening of the first piston 31, and the fluid pressure reaction force due to the brake fluid pressure is applied to the second force transmitting member 2.
16 and the spool 114 via the first force transmitting member 116.
It is transmitted to.

A pressure damper chamber R104 is formed between the front flange of the spool 114 and the second force transmitting member 216. The spool 114 moves forward and the pressure damper chamber R
When the volume of the pressure damper 104 decreases, the brake fluid in the pressure damper chamber R104 flows into the orifice 162 and the first force transmitting member 11.
6 and the communication groove 13b of the second input rod 13
Through the drain chamber R8 and the reservoir 7. That is, due to the viscous resistance when the brake fluid in the pressure damper chamber R104 passes through the orifice 162 and the elastic resistance due to the compression of the spring 165, a moderate resistance is applied to the forward movement of the spool 114, Vibration and overstroke are prevented.

When the forward movement speed of the spool 114 is high and the hydraulic pressure in the pressure damper chamber R104 is higher than a predetermined pressure, the outer seal of the seal cup 163 set to the predetermined valve opening pressure is moved inward. Falling down, orifice 16
A communication path larger than the passage area of No. 2 is formed. Therefore, the brake fluid in the pressure damper chamber R104 can flow out to the drain chamber R8 and the reservoir 7 without receiving a large viscous resistance. That is, the pressure damper chamber R
Even when the volume of the pressure chamber 104 is suddenly reduced, the brake fluid in the pressure damper chamber R104 flows smoothly to the drain chamber R8 side, so that the fast forward movement of the spool 114 is not hindered.

[0051]

According to the present invention, it is possible to provide a low-cost hydraulic brake device which does not require tuning of the pressure adjusting means.

[Brief description of the drawings]

FIG. 1 is an overall view of a hydraulic brake device according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a partially enlarged view of a hydraulic brake device according to a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 7 reservoir 11 brake pedal (brake operating member) 14 spool (pressure regulating means) 30 power piston 31 first piston (power piston) 32 second piston (power piston) 33 third piston (power piston) 34 fourth piston (power) Piston) 36 Master piston 41 Reaction disk 60, 160 Check valve 61b, 162 Orifice AS Auxiliary hydraulic pressure source AC accumulator (auxiliary hydraulic pressure source) D1 Hydraulic pressure sensor (auxiliary hydraulic pressure source) HP Hydraulic pump (auxiliary hydraulic pressure source) ) M electric motor (auxiliary hydraulic pressure source) MC master cylinder R3 first power chamber (power chamber) R4 pressure damper chamber R6 second power chamber (pressurizing chamber)

Claims (4)

[Claims] 1. A master cylinder for driving a master piston forward in response to operation of at least a brake operating member to increase brake fluid in a reservoir and output brake fluid pressure;
A power piston disposed behind the master piston to form a power chamber, an auxiliary hydraulic pressure source for increasing the brake fluid in the reservoir to a predetermined pressure and outputting a hydraulic pressure, and connected to the auxiliary hydraulic pressure source And a pressure control means connected to the reservoir for adjusting the output hydraulic pressure of the auxiliary hydraulic pressure source to a predetermined pressure and supplying the output hydraulic pressure to the power chamber. A hydraulic brake device comprising a damper chamber, wherein the pressure damper chamber is connected to the reservoir via an orifice. 2. The hydraulic brake device according to claim 1, wherein a check valve for permitting the flow of brake fluid from the pressure damper chamber to the reservoir is provided in parallel with the orifice. 3. The hydraulic brake device according to claim 1, wherein said pressure adjusting means comprises a spool valve. 4. The pressurizing chamber according to claim 3, further comprising a pressurizing chamber selectively connected to the auxiliary hydraulic pressure source or the reservoir between the power piston and the spool valve. A hydraulic brake device, wherein when connected to a pressure source, the spool valve is urged forward independently of the brake operating member.