JP3382133B2 - Vehicle hydraulic brake system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic brake system for supplying a brake hydraulic pressure to a wheel cylinder of a vehicle wheel, and more particularly to a hydraulic chamber for moving a piston forward by driving a brake operating member. The present invention relates to a vehicle hydraulic brake device that outputs brake hydraulic pressure.

[0002]

2. Description of the Related Art Various types of devices are known for hydraulic brake devices for automobiles. For example, a device provided with an auxiliary hydraulic pressure source and pressure regulating valve means is disclosed in US Pat. No. 392.
Some are disclosed in Japanese Patent No. 8970. In the publication,
Regarding a master cylinder utilizing the pressure of a pressurized fluid source, having a piston slidably accommodated in a cylinder bore,
A pressure chamber connected to the brake hydraulic circuit is formed in front of the power chamber, a power chamber connected to the pressurized fluid source is formed behind the pressure chamber, and a control valve for controlling the supply of fluid from the pressurized fluid source is provided. A master cylinder device is disclosed. In this publication, in a master cylinder having a pressurized fluid source, the piston is directly driven by the operation of the brake pedal, but it is an object of the invention to configure so that an inlet or an inlet seal that moves in a pressurized state is not required. A first piston that compresses the pressure chamber connected to the hydraulic circuit, a control valve that controls the output hydraulic pressure of the pressurized fluid source, and a second piston that drives this control valve are provided. There has been proposed a master cylinder device in which one end of a piston is exposed in a pressure chamber and the other end is exposed in a power chamber.

[0003]

In the conventional hydraulic brake device including the master cylinder device described in the above publication, when the piston is driven forward according to the operation of the brake pedal and then the brake pedal is suddenly released, the piston is released. Rapidly retracts and produces an impulsive sound when the piston abuts the inner surface of the cylinder body. Further, this impact sound is amplified as vibration of the brake pedal system and becomes an unpleasant sound that cannot be overlooked by the driver. Therefore, a means for reducing this has been desired.

Therefore, the present invention is a hydraulic brake device for a vehicle which outputs a brake fluid pressure from a pressure chamber by driving the piston forward in response to the operation of the brake operating member, and the piston when the brake operating member is released. The object is to reduce the impact sound generated due to the backward movement of the vehicle and to secure a good brake feeling.

[0005]

In order to achieve the above object, the present invention comprises a cylinder body in which a piston is slidably accommodated in a liquid-tight manner, and a pressure chamber is formed in front of the piston.
In a hydraulic brake device of a vehicle including a master cylinder for driving the piston forward in response to an operation of a brake operating member to output a brake hydraulic pressure from the pressure chamber, the hydraulic chamber is formed behind the piston, and A communication passage that can communicate with the liquid chamber is formed, and a flow passage area of the communication passage with respect to the liquid chamber is set to a minute area that forms a throttle at least in an initial movement region from the rear end position of the piston, and the initial movement region is set. After passing over, the piston is formed so as to increase in accordance with the forward movement of the piston. Thus, when the brake operating member is released and the piston is retracted and the piston comes into contact with the cylinder body, the liquid chamber functions as a damper chamber, so that the impact noise is reduced. still,
As a means for forming the throttle, it is desirable that the outer peripheral surface of the piston rear portion is tapered and the gap between the inner surface of the cylinder body and the inner surface of the piston increases toward the rear of the piston. On the contrary, the inner surface of the cylinder body may be tapered.

Further, in the hydraulic brake device, the piston may be provided with a check valve that allows the flow of the brake fluid from the communication passage to the fluid chamber and blocks the flow in the opposite direction. A cushioning member may be provided on at least one of the piston and the cylinder body that abuts the piston at the rear end position of the piston.

Further, according to the present invention, a master piston is housed in a cylinder body so as to be slidable in a liquid-tight manner, a pressure chamber is formed in front of the master piston, and a power chamber is formed in the rear of the master piston. A master cylinder that drives the master piston forward in response to an operation to output a brake fluid pressure from the pressure chamber, an auxiliary fluid pressure source that boosts the brake fluid to a predetermined pressure and outputs a power fluid pressure, and the cylinder body. A control piston which is slidably housed in the front of the master piston in a liquid-tight manner and is arranged so as to interlock with the master piston; and the output power hydraulic pressure of the auxiliary hydraulic pressure source is introduced into the pressure regulation chamber to perform the control. Pressure regulating valve means for regulating the pressure to a predetermined pressure according to the movement of the piston, and the brake fluid pressure regulated by the pressure regulating valve means is applied to the power chamber of the master cylinder via a fluid pressure passage. In the hydraulic brake device for a vehicle that assists the master piston, a communication passage extending from the opening of the hydraulic passage to the power chamber is formed with a throttle at least in an initial movement region from the rear end position of the master piston. The flow path area may be set to be a minute flow path area and to increase in accordance with the forward movement of the master piston after exceeding the initial movement region.

Also in this hydraulic brake device, when the master piston is retracted by releasing the brake operating member and the master piston comes into contact with the cylinder body, the power chamber functions as a damper chamber, so that an impact is generated. The sound is reduced. It should be noted that the pressure regulating valve means includes a spool which is locked in front of the control piston in the pressure regulating chamber, and a sleeve which is fixed to the cylinder body and accommodates the spool slidably. The output power hydraulic pressure of the auxiliary hydraulic pressure source may be introduced into the pressure adjusting chamber and adjusted in accordance with the relative movement of the spool with respect to the sleeve due to the movement of the piston.

[0009]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a brake fluid pressure control device for use in an embodiment of the present invention.
A master cylinder portion and a regulator portion serving as pressure regulating valve means are formed in h, and a brake pedal 2 serving as a brake operating member is provided on the vehicle rear side (right side in FIG. 1).
The pedaling force applied to the brake pedal 2 is transmitted as a brake actuating force via the push rod 3 and the input member 4, and in response to this, the output brake hydraulic pressure of the master cylinder portion and the regulator portion is applied to the front right and left wheels of the vehicle. F
R, FL and the wheel cylinders Wfr, Wfl, Wrr, Wrl of the rear right and left wheels RR, RL (in FIG. 1, the front and rear wheels FR, RR on the right side of the vehicle).
And wheel cylinders Wfr and Wrr mounted on each wheel
Only shown).

The cylinder body 1h is formed with stepped holes composed of holes 1a, 1b, 1c having different inner diameters,
The master piston 10 and the control piston 21 are housed therein, and a pressure chamber R2 is defined between the master piston 10 and the control piston 21. The hole 1a communicates with the power chamber R1 having an inner diameter larger than this. A control piston 21 is slidably and liquid-tightly fitted into the hole 1b having the smallest diameter. The master piston 10 is composed of a first piston 11 and a second piston 12, and has a first piston 11 in each of the hole 1b and a hole 1a having a larger diameter.
Both ends of are accommodated and supported. That is, the outer surface of the first piston 11 has a land portion 11a having a small diameter at the front end.
And a large-diameter land portion 11b is formed on the rear side at a predetermined distance in the axial direction. The former is provided with an annular cup-shaped seal member 14 and is liquid-tightly slid in the hole 1b. The latter is freely fitted, and the latter is slidably fitted in the hole 1a and arranged so as to come into contact with the second piston 12.

On the side of the land 11a of the first piston 11, a cylindrical support 11s is formed so as to extend, and a recess 11e is formed in the axial direction. In addition, a through hole 11c is formed in the radial direction of the first piston 11, and an axial communication hole 11d that communicates with the through hole 11c is formed and opens in the recess 11e. The retainer 16 is attached to the support portion 11s, and the valve body 25 is locked to the retainer 16 to restrict the movement of the valve body 25 toward the control piston 21. An elastic member such as rubber is adhered to one end of the valve body 25, and is configured to abut the communication hole 11d so as to seal the communication hole 11d. Disc 25
A rod 25b is integrally formed on the other end side of the, and a locking portion 25c is formed on the front end thereof. Further, the communication hole 1 is formed in the axial direction of the peripheral portion of the land portion 11a of the first piston 11.
1f is formed. An annular seal member 14 is attached to the front end of the communication hole 11f on the pressure chamber R2 side, and a check valve is constituted by these members. Therefore, the liquid supply chamber R5 can communicate with the pressure chamber R2 through the communication hole 11c, the communication hole 11d, and the communication hole 11f. still,
The liquid supply chamber R5 communicates with the reservoir 6 via the hydraulic pressure passage 1e.

Further, a second piston 12 is housed on the rear side of the first piston 11. Second piston 1
2, a land portion 12a is formed on the front outer surface thereof, and an annular seal member 12b is attached to the land portion 12a and fitted in the hole 1a so as to be slidable in a liquid-tight manner. The seal member 12b supplies the power chamber R1 with the power chamber R1. The liquid chamber R5 is separated. Further, a recess 12c is formed behind the second piston 12, the input member 4 is housed in the recess 12c, and the input member 4 is screwed into the contact member 5 at the front. The second piston 12 has its front end face opposed to the rear end face of the first piston 11,
The pressing force from the brake pedal 2 is transmitted to the first piston 11 via the input member 4 and the contact member 5. The main body of the second piston 12 is supported by a cylindrical sleeve 17. This sleeve 1
An annular groove is formed on the inner surface and the outer surface of 7, and an annular groove is also formed on the inner surface that is separated from the inner surface by a certain distance in the axial direction. Sealing members 17a, 1 are provided in these grooves, respectively.
7b and a seal member 18 are housed in the power chamber R
The sealing property for 1 is secured. The first piston 11 and the second piston 12 may be integrally formed.

FIG. 2 is an enlarged view showing the second piston 12 and the power chamber R1 portion, and the power chamber R1 corresponds to the liquid chamber of the present invention. Further, as shown in FIG. 3 in which the opening of the hydraulic passage 1r to the power chamber R1 is enlarged, a taper portion 12d is formed on the rear outer periphery of the land portion 12a of the second piston 12.
Is formed, and the tapered portion 12d and the power chamber R1 are formed.
Communication path 1 with the inner wall of the cylinder (the inner surface of the cylinder body 1h)
t is formed. The communication passage 1t is formed so that the flow passage area for the power chamber R1 is minimized when the second piston 12 is at the rear end position of the initial position, as shown in FIG. Then, in accordance with the forward movement of the second piston 12, the flow passage area gradually increases in the initial movement region,
Beyond this, the communication passage 1t has a sufficient flow passage area as shown in FIG. The taper portion 1 of the second piston 12
Instead of 2d, the inner surface of the cylinder body 1h facing the rear outer peripheral surface of the land portion 12a may be formed in a tapered shape.

As described above, the flow passage area of the communication passage 1t with respect to the power chamber R1 is set to be a minute area at least in the initial movement region from the rear end position of the second piston 12 to form the "throttle". After passing the initial movement region, a sufficient flow passage area is secured. On the contrary, when the second piston 12 retracts, a sufficient flow passage area is secured until reaching the initial movement region, but the tapered portion 12d of the second piston 12 causes the hydraulic passage 1r to move. The opening is gradually blocked, the flow passage area is gradually reduced, and a diaphragm is formed when reaching the initial movement region.

Next, a regulator portion is formed in the front portion of the cylinder body 1h, and an auxiliary hydraulic pressure source 40 is connected to this, and the output power hydraulic pressure is appropriately controlled and output. The auxiliary hydraulic pressure source 40 includes a hydraulic pressure pump 43 driven by an electric motor 42, the input side is connected to the reservoir 6 and the output side is connected to the accumulator 44,
The power hydraulic pressure is supplied from the accumulator 44 to the communication hole 31d via the hydraulic pressure passage 1p. The control piston 21 housed in the hole 1c is formed with a pair of land portions 21a and 21b at a predetermined distance in the axial direction, but an annular seal member 24 is attached only to the front land portion 21a. The rear land portion 21b communicates with each other. Therefore, the pressure chamber R2 is separated from the regulator chamber R3 described later by the seal member 24, and the seal member 24 and the land portion 11a of the first piston 11 are separated.
A pressure chamber R2 is defined between the pressure chamber R2 and the seal member 14 attached to the pressure chamber R2.

As is apparent from FIG. 1, the control piston 21 is formed with a through hole 21c that penetrates in the radial direction and extends in the axial direction and opens at the rear end. Front land part 2
The locking pin 2 is located at the rear end of the la 1a and extends in the radial direction.
8 is fixed to the cylinder body 1h, which allows the control piston 21 to move forward, but restricts the backward movement (movement in the direction of the master piston 10). The through hole 21c of the control piston 21 also extends in the axial direction, and a cylindrical support portion 21s is integrally formed so as to surround the through hole 21c, and the locking portion 25c of the valve body 25 is housed therein. Has been done. A retainer 26 is mounted on the support portion 21s, and a retaining portion 25c is retained by the retainer 26 to restrict movement of the valve body 25 toward the master piston 10. Further, a recess is formed at the axial end of the control piston 21 in the direction opposite to the retainer 26, and the tip of the spool 32 described later is held in this recess.

In the stepped hole 1c communicating with the hole 1b, cylindrical sleeves 31 and 36 are fitted, and a regulator chamber R3 as a pressure adjusting chamber is formed between the sleeve 31 and the control piston 21. Has been done. A plurality of annular grooves are formed on the outer peripheries of the sleeves 31 and 36, and annular sealing members are fitted in the respective grooves. Communication holes 31d and 31f are provided between these adjacent seal members in the radial direction of the sleeve 31.
Is formed, and the communication holes 36b, 3 are formed in the radial direction of the sleeve 36.
6c is formed. A spool 32 is slidably accommodated in the hollow portion of the sleeve 31.
The opening of the communication hole 31f is arranged to be blocked by the forward movement of the.

In the axial direction of the sleeve 31, there is formed a communication hole 31e having one end communicating with the communication hole 31f and the other end communicating with the regulator chamber R3. When the communication hole 31f is open, the regulator chamber R3 is formed. Are communication holes 31e, 3
It is configured to be able to communicate with the hydraulic passage 1s via 1f. The communication hole 31d is communicatively connected to the auxiliary hydraulic pressure source 40 via the hydraulic pressure passage 1p, but is shielded by the outer peripheral surface of the spool 32 at the position of FIG. Furthermore, the communication hole 3
An annular groove 31c is formed on the inner peripheral surface of the sleeve 31 at the rear of 1d. The communication holes 36b and 36c are connected to the hydraulic passages 1q and 1r, respectively.

A plunger 35 is fitted to the front end of the spool 32 so as to project in the axial direction.
The rear end is located in the regulator chamber R3 and is locked to the control piston 21. That is, the retainer 33 is supported in the recess in front of the control piston 21, and the retainer 33 and the sleeve 3 are supported.
A spring 34 is stretched between the control piston 21 and the spring 1, and the spool 32 is urged to come into contact with the control piston 21. At the initial position (retracted position) of the control piston 21, the opening of the communication hole 31f is not blocked by the spool 32, and the regulator chamber R3 passes through the communication holes 31e and 31f of the sleeve 31 and the hydraulic pressure passage 1s. And communicates with the reservoir 6 and is filled with the brake fluid at atmospheric pressure.
Further, on the outer peripheral surface of the spool 32, an annular groove 32b is formed in a retracted position over a predetermined range in the axial direction centered on the rear end of the sleeve 31, and the sleeve 31 is provided in front of the groove 32b at a predetermined distance. An annular groove 32c is formed at a position facing the groove 31c.

At the position shown in FIG. 1, the regulator chamber R3 is in communication with the reservoir 6 through the communication holes 31e and 31f of the sleeve 31 and the hydraulic passage 1s, and is at atmospheric pressure. When the spool 32 moves forward with the forward movement of the control piston 21, the communication hole 31f of the sleeve 31 is blocked, and instead the communication hole 31d faces the groove 32c of the spool 32, and the groove 31c and the groove 32b.
Face each other and thus communicate with the auxiliary hydraulic pressure source 40. As a result, the power hydraulic pressure of the auxiliary hydraulic pressure source 40 is adjusted to the regulator chamber R3.
It is supplied inside to boost the pressure.

On the other hand, the hollow portion of the sleeve 36 is formed in a stepped hole shape, the transmission member 37 is slidably accommodated in the small diameter hole portion in the axial direction, and its rear end faces the tip of the plunger 35. It is arranged. Further, the sleeve 36
An elastic member 38 made of rubber, for example, is fitted in the large-diameter hole portion of the transmission member 37, and is arranged so that the tip of the transmission member 37 abuts on it. In this embodiment, a truncated cone-shaped contact member (reference numeral omitted) is provided at the tip of the transmission member 37, but the tip of the transmission member 37 may be formed in the same shape. A plug 39 is fitted on the tip of the hollow portion of the sleeve 36, and a regulator chamber R4 is formed between the plug 39 and the elastic member 38.

The regulator chamber R4 is connected to the regulator chamber R3 via the communication hole 36b and the hydraulic pressure passage 1q, and is also connected to the power chamber R1 via the communication hole 36c and the hydraulic pressure passage 1r. The pressure chamber R2 is connected to the wheel cylinder Wfr via the hydraulic pressure passage 1n, and the power chamber R1 is connected to the wheel cylinder Wrr via the hydraulic pressure passage 1k.
Connected to.

Next, the overall operation of the hydraulic brake device having the above construction will be described. 1 and 2 show a state in which the brake pedal 2 is not operated. From this state, the brake pedal 2 is operated, and the first and the first members are pushed through the push rod 3, the transmission member 4 and the contact member 5. Two pistons one
When 1 and 12 are pressed forward (to the left in FIG. 1), the valve body 25 comes into contact with the first piston 11, the elastic member of the valve body 25 closes the communication hole 11d, and the pressure chamber R2 and the pressure chamber R2 are connected. The communication with the liquid chamber R5 is cut off and a sealed state is established. in this way,
With the communication between the pressure chamber R2 and the liquid supply chamber R5 blocked,
The first and second pistons 11, 12 are the brake pedal 2
When driven by the operating force of 1, the first piston 11 is held in the state shown in FIG. 1 via the spring 19, so that they advance together.

Therefore, the communication hole 31f is closed by the spool 32 supported by the control piston 21, and the communication with the reservoir 6 is blocked. At the same time, the power hydraulic pressure from the auxiliary hydraulic pressure source 40 flows into the regulator chamber R3 from the hydraulic pressure passage 1p through the communication hole 31d, the annular grooves 31c and 32c, and the groove 32b, and is used as the regulator hydraulic pressure. 1q
Is supplied to the regulator chamber R4 via the
It is supplied to the power chamber R1 via r. by this,
The first piston 11 and the second piston 12 are assisted and move forward, the pressure chamber R2 is further compressed, the master cylinder hydraulic pressure is output from the hydraulic pressure passage 1n to the wheel cylinder Wfr, and the hydraulic pressure passage 1k is generated. The regulator hydraulic pressure is output to the wheel cylinder Wrr via.

During this time, the force applied to the control piston 21 by the regulator hydraulic pressure in the regulator chamber R3 is
If it is larger than the force applied to the control piston 21 by the master cylinder hydraulic pressure in the pressure chamber R2, the control piston 2
1 moves rearward, the communication hole 31f opens and communicates with the reservoir 6, so that the pressure inside the regulator chamber R3 is reduced. When the relationship of the force applied to the control piston 21 is opposite to the above, the control piston 21 moves forward, the communication hole 31f is blocked, and the regulator chamber R3 is replaced by the communication hole 31d.
Since it communicates with the auxiliary hydraulic pressure source 40 via the like, the pressure inside the regulator chamber R3 is increased. Such a control piston 21
By repeating the movement of the spool 32 with the movement of
The control hydraulic pressure applied to the control piston 21 is controlled to be equal to the master cylinder hydraulic pressure. Then, until the force due to the regulator hydraulic pressure in the regulator chamber R4 is transmitted to the plunger 35 via the elastic member 38 and the transmission member 37, the regulator hydraulic pressure substantially proportional to the master cylinder hydraulic pressure is output, and the first hydraulic pressure is output. Brake fluid pressure characteristics can be obtained.

Further, the regulator hydraulic pressure is increased, the central portion of the elastic member 38 is displaced rearward by the regulator hydraulic pressure supplied to the regulator chamber R4, the transmission member 37 abuts on the plunger 35, and the spool 32 is rearwardly moved. When pressed, the opening area of the communication hole 31f increases. As a result, the regulator hydraulic pressure in the regulator chamber R3 is reduced, and is substantially proportional to the master cylinder hydraulic pressure, but has a pressure increasing gradient that is gentler than the pressure increasing gradient of the first brake hydraulic pressure characteristic.
The brake fluid pressure characteristic of is obtained.

In the above-mentioned operation, when the second piston 12 advances from the position of FIG. 3 in response to the operation of the brake pedal 2, as shown in FIG. 4, the power chamber R1 of the communication passage 1t.
The area of the flow path is increased. Therefore, the regulator hydraulic pressure is smoothly introduced into the power chamber R1 via the hydraulic pressure passage 1r. Then, when the operation of the brake pedal 2 is released,
The second piston 12 retreats at once, but the flow passage area of the communication passage 1t gradually decreases as the second piston 12 retreats, and a throttle is formed in the initial movement region. As a result, the power chamber R1 functions as a damper chamber, the impact when the second piston 12 contacts the sleeve 17 becomes extremely small, and the generation of impact noise is suppressed.

FIG. 5 shows another embodiment of the present invention. In addition to the configuration of the above embodiment, the second piston 12 is provided.
A communication hole 12e extending from the communication passage 1t portion to the rear end side is formed at the rear end of the communication passage 1t. The valve 50 is provided. With this configuration, the second piston 12 is driven forward and the hydraulic pressure passage 1 is driven.
When the regulator hydraulic pressure is supplied from r to the power chamber R1, the check valve 50 is opened and a sufficient flow passage area is secured, so that good responsiveness is obtained. On the other hand, when the operation of the brake pedal 2 is released and the second piston 12 retracts, the check valve 50 blocks the communication hole 12e, so that the same damper effect as that of the above-described embodiment is maintained.

FIG. 6 shows still another embodiment of the present invention. In addition to the configuration of the embodiment of FIG. 3, a cushioning member 60 is provided at the rear end of the land portion 12a of the second piston 12. Is. With this cushioning member 60, the brake pedal 2
Is released, the impact when the second piston 12 retracts and comes into contact with the sleeve 17 is mitigated, so that a further impact noise suppressing effect can be obtained in addition to the damper effect by the communication passage 1t and the power chamber R1. . The cushioning member 60 may be provided on the sleeve 17 side. In addition, sleeve 1
7 is integrated with the cylinder body 1h and is included in the cylinder body in the present invention.

[0030]

Since the present invention is constructed as described above, it has the following effects. That is, according to the vehicle hydraulic brake device of the first aspect, the liquid chamber functions as a damper chamber when the brake operating member is released and the piston retreats, and the piston comes into contact with the cylinder body. The impact noise is reduced, and good brake feeling can be secured.

Further, in the hydraulic brake device according to the second aspect, when the brake operating member is operated and the master piston advances, the flow of the brake fluid from the communication passage into the fluid chamber through the check valve. Since it is allowed, good responsiveness is obtained. Moreover, when the brake operating member is released and the master piston retracts, and the master piston comes into contact with the cylinder body, the check valve blocks the flow from the liquid chamber to the communication passage, so that the damper effect is maintained. Impact noise is reduced, and good brake feeling can be secured.

Alternatively, in the hydraulic brake device according to a third aspect of the present invention, when the brake operating member is released and the piston retracts and the piston comes into contact with the cylinder body, the shock is cushioned by the buffer member. In addition to the damper effect of the communication passage and the liquid chamber, a further shock noise suppression effect can be obtained, and a good brake feeling can be secured.

Also, in the hydraulic brake device according to the fourth aspect, the power chamber functions as a damper chamber when the brake operating member is released and the master piston retracts and the master piston contacts the cylinder body. Because
Impact noise is reduced, and good brake feeling can be secured.

[Brief description of drawings]

FIG. 1 is a sectional view of a hydraulic brake device for a vehicle according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a rear portion of the vehicle hydraulic brake device according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view showing, in an enlarged manner, an opening portion of the hydraulic pressure passage of the hydraulic brake device to the power chamber in the embodiment of the present invention.

FIG. 4 is an enlarged cross-sectional view showing an opening portion of a hydraulic passage to a power chamber when a master piston moves forward in an embodiment of the present invention.

FIG. 5 is a cross-sectional view showing, in an enlarged manner, an opening portion of a hydraulic pressure passage to a power chamber in a hydraulic brake device according to another embodiment of the present invention.

FIG. 6 is a cross-sectional view showing, in an enlarged manner, an opening portion of a hydraulic pressure passage to a power chamber in a hydraulic brake device according to still another embodiment of the present invention.

[Explanation of symbols]

1h cylinder body 1e, 1p, 1q, 1r, 1s, 1k, 1n Hydraulic path 1t communication passage 2 brake pedal 6 reservoir 10 Master piston 11 First piston 12 Second piston 12d taper part 17 Sleeve 21 Control piston 32 spools 40 Auxiliary hydraulic pressure source R1 power room R2 pressure chamber R3, R4 regulator room R5 liquid supply room

Front page continuation (72) Inventor Yasuo Konishi 2-1-1 Asahi-cho, Kariya city, Aichi Prefecture Aisin Seiki Co., Ltd. (72) Inventor Junichi Okuno 2-1-1 Asahi-cho, Kariya city Aichi Prefecture Aisin Seiki Co., Ltd. (72) Inventor Yoshihisa Nomura 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (56) References: 62-15073 (JP, U) US Patent 3928970 (US, A) (58) Field (Int.Cl. ⁷ , DB name) B60T 13/12

Claims (4)

(57) [Claims] 1. A piston is accommodated in a cylinder body so as to be slidable in a liquid-tight manner, and a pressure chamber is formed in front of the piston.
In a hydraulic brake device of a vehicle including a master cylinder for driving the piston forward in response to an operation of a brake operating member to output a brake hydraulic pressure from the pressure chamber, the hydraulic chamber is formed behind the piston, and A communication passage that can communicate with the liquid chamber is formed, and a flow passage area of the communication passage with respect to the liquid chamber is set to a minute area that forms a throttle at least in an initial movement region from the rear end position of the piston, and the initial movement region is set. A hydraulic brake device for a vehicle, wherein the hydraulic brake device is formed so as to increase in accordance with the forward movement of the piston after exceeding the above. 2. The vehicle according to claim 1, wherein the piston is provided with a check valve that allows the flow of the brake fluid from the communication passage to the fluid chamber and blocks the flow in the opposite direction. Hydraulic brake device. 3. The liquid for a vehicle according to claim 1, wherein a shock absorbing member is provided on at least one of the piston and the cylinder body that abuts on the piston at a rear end position of the piston. Pressure braking device. 4. A master piston is housed in a cylinder body so as to be slidable in a liquid-tight manner, a pressure chamber is formed in front of the master piston, and a power chamber is formed in the rear of the master piston, according to an operation of a brake operating member. A master cylinder that drives the master piston forward to output a brake fluid pressure from the pressure chamber, an auxiliary hydraulic pressure source that boosts the brake fluid to a predetermined pressure to output a power fluid pressure, and the master in the cylinder body. A control piston arranged so as to be fluid-tightly slidably housed in front of the piston and arranged to interlock with the master piston;
A pressure regulating valve means for regulating the output power hydraulic pressure of the auxiliary hydraulic pressure source into the pressure regulating chamber and regulating the pressure to a predetermined pressure in accordance with the movement of the control piston, and the brake hydraulic pressure regulated by the pressure regulating valve means. In a hydraulic brake device for a vehicle, which is applied to a power chamber of the master cylinder via a hydraulic passage to assist the master piston, a communication passage extending from an opening of the hydraulic passage to the power chamber is at least the master. In the initial movement region from the rear end position of the piston, a minute flow passage area is formed to form a restriction, and after passing the initial movement region, the flow passage area is increased according to the forward movement of the master piston. A hydraulic brake device for a vehicle.