JPH11240441A - Brake fluid pressure servo system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To assure appropriate pedal stroke by making it possible to change strokes of the brake pedal. SOLUTION: At the front end of a power piston 8, a primary piston 48' of a master cylinder 2 is provided. Also, between the primary piston 48' and a secondary piston 48", a hydraulic chamber 55 is provided. This hydraulic chamber 55 is connected via an orifice 76 to a stroke simulator 75 of a variable stroke unit 71. When operating, hydraulic fluid in the hydraulic chamber 55 is introduced to the stroke simulator 75 by advance of the power piston 8. Accordingly, the pedal stroke of the brake pedal that is coupled to an input shaft 18 increases for the amount of the hydraulic fluid taken up by the stroke simulator 75.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a brake hydraulic boosting system which obtains a large braking force by boosting an input to a predetermined magnitude by a hydraulic pressure and outputting the boosted output. In particular, it belongs to the technical field of a brake hydraulic booster system capable of changing the stroke of a brake pedal.

[0002]

2. Description of the Related Art An automobile brake hydraulic booster system is
A hydraulic booster is provided to obtain a large brake force by boosting a small pedaling force with a hydraulic pressure. As an example of such a hydraulic booster, Japanese Utility Model Registration No. 255151658 has proposed. There is something.

FIG. 5 is a view showing a hydraulic booster registered as a utility model. In the figure, 1 'is a brake fluid pressure booster,
2 'is a housing, 3' is a plug, 4 'is a power piston, 5' is a control valve, 6 'is a valve seat member, 7' is a cylindrical fixing member, 8 'is a nut, 9' is a ball valve, 10 ' Is the valve body, 1
1 'is a cylindrical member, 12' is an input shaft, 13 'is a cylindrical stopper member, 14' is a reaction piston, 15 'is a power chamber, 1'
6 'is an output shaft.

[0004] In the brake hydraulic booster 1 ', the ball valve 9' of the control valve 5 'is inoperative when not shown.
Is seated on the valve seat member 6 'and the cylindrical member 1
The tip valve portion 1 'is separated from the ball valve 9'. Therefore, the power chamber 15 'is shut off from the input port 17' which is always connected to the hydraulic pressure source (not shown), and the chamber 18 'which is also always connected to the reservoir (not shown).
And no hydraulic pressure is introduced into the power chamber 15 ′,
The power piston 4 'does not operate.

[0005] When the brake pedal (not shown) is depressed from this inoperative state, an input is applied to the input shaft 12 ′ and the input shaft 12 ′ moves forward, the tubular member 11 ′ also moves forward, and the cylindrical member 11 ′. Of the control valve 5 'comes into contact with the ball valve 9' of the control valve 5 'and pushes the ball valve 9' to separate from the valve seat member 6 '. As a result, the power chamber 15 'communicates with the input port 17' and is shut off from the chamber 18 ', whereby pressure fluid is introduced into the power chamber 15' and the power piston 4 'operates. By the operation of the power piston 4 ', the brake hydraulic booster 1' outputs from the output shaft 16 'to operate a piston of a master cylinder (not shown), and the master cylinder generates a master cylinder pressure. This master cylinder pressure is introduced into, for example, the wheel cylinders of both systems in a two-system brake system, and the brakes of both systems operate. When the hydraulic pressure in the power chamber 15 'reaches a magnitude corresponding to the input, the ball valve 9' is seated on the valve seat member 6 ', and the output of the brake hydraulic booster 1' boosts the input. Size.

When the brake pedal is released to eliminate the input, the input shaft 12 'is retracted by a return spring (not shown), so that the cylindrical member 11' is also retracted, and the distal valve portion of the cylindrical member 11 'is moved to the control valve. It is separated from the 5 'ball valve 9'. As a result, the power chamber 15 'is shut off from the input port 17 and communicates with the chamber 18' so that the hydraulic pressure introduced into the power chamber 15 'is discharged to the reservoir and the power piston 4'
Is retracted by the return spring 20 '. Input shaft 1
A cylindrical stopper member 13 'fixed to 2' is a plug 3 '
When the input shaft 12 'comes into contact with the stopper 21', the input shaft 12 'does not retreat any further, and is at the retreat limit, and returns to the inoperative state shown in the figure. When the hydraulic pressure in the power chamber 15 'is completely discharged, the power piston 4' also returns to the inoperative state shown in the figure, the brake hydraulic booster 1 'does not output, and the master cylinder is also inactive.

In this conventional brake hydraulic booster 1 ', the relationship between the output and the stroke of the input shaft 12' is constant.

[0008]

By the way, in the dual system brake, for example, the hydraulic pressure introduced into the power chamber 15 'of the brake hydraulic booster 1' as described above is applied to one system. The brake system of one system is directly introduced to the wheel cylinder to operate the brake of one system, and the master cylinder pressure of the master cylinder operated by the output of the brake hydraulic booster 1 'is introduced to the wheel cylinder of the other system to (Japanese Patent Application No. 8-309214).
issue).

In this semi-full power brake system, the hydraulic pressure in the power chamber 15 'is directly introduced to one of the wheel cylinders. Therefore, when the same braking force is obtained, the stroke of the brake pedal is reduced by the aforementioned master cylinder. The pressure is reduced as compared with the conventional brake system in which the pressure is introduced into both systems of the wheel cylinder. For this reason, the driver will feel uncomfortable when the brake is operated.

Further, it is desirable that a more appropriate pedal stroke can be set according to a vehicle condition such as a loaded condition, a brake condition, or a driver. However, the relationship between the output and the pedal stroke is constant. It is difficult for the conventional brake hydraulic booster 1 'to meet this demand.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to make it possible to change the stroke of a brake pedal so that a brake hydraulic pressure booster capable of providing an appropriate pedal stroke. Is to provide a system.

[0012]

In order to solve the above-mentioned problems, a brake hydraulic boosting system according to the first aspect of the present invention comprises:
A hydraulic pressure source for generating hydraulic pressure, a reservoir for storing hydraulic fluid,
A power piston that generates an output, a power chamber facing a pressure-receiving surface of the power piston, and a non-operating chamber that shuts off the power chamber from the hydraulic pressure source and communicates with the reservoir;
A control valve that shuts off the power chamber from the reservoir during operation and communicates with the hydraulic pressure source to introduce the hydraulic fluid from the hydraulic pressure source into the power chamber in accordance with its operation; A master cylinder having an input shaft to be operated, a brake pedal to which an input is applied to operate the input shaft, a master cylinder piston operated and controlled by an output of the power piston to generate a master cylinder pressure, and a master of the master cylinder. A brake cylinder that generates a braking force by the introduction of a cylinder pressure, a liquid chamber provided between the power piston and the master cylinder piston, and sealed at least when the power piston is operated; A strobing cylinder connected to a pressure receiving cylinder into which the hydraulic fluid is introduced when the power piston operates. It is characterized by and a click simulator.

The invention according to a second aspect is characterized in that an on-off valve arranged between the liquid chamber and the stroke simulator is connected to the liquid chamber, and the hydraulic fluid in the liquid chamber is actuated when the power piston is operated. A second pressure receiving cylinder into which is introduced, and a communication / shutoff control valve disposed between the second pressure receiving cylinder and the liquid chamber, for controlling communication / shutoff therebetween. It is characterized by.

According to a third aspect of the present invention, in the two-brake system, a hydraulic pressure source for generating hydraulic pressure, a reservoir for storing hydraulic fluid, a power piston for generating output,
A power chamber in which a pressure receiving surface of the power piston faces, and a power chamber that is disconnected from the hydraulic pressure source when not operating and communicates with the reservoir when not in operation. A control valve for introducing the hydraulic fluid from the hydraulic pressure source into the power chamber in accordance with the operation thereof, an input shaft for controlling the operation of the control valve, and an input being applied to operate the input shaft. A brake pedal, a master cylinder having a master cylinder piston that is operated and controlled by the output of the power piston to generate a master cylinder pressure, and one of the systems that generates a braking force by introducing hydraulic pressure in the power chamber. A brake cylinder, and a brake cylinder of the other system that generates a braking force by introducing a master cylinder pressure of the master cylinder; A liquid chamber provided between a power piston and the master cylinder piston and sealed at least when the power piston is operated, and connected to the liquid chamber, and the hydraulic fluid in the liquid chamber is introduced when the power piston is operated. And a stroke simulator.

According to a fourth aspect of the present invention, an on-off valve is provided between the liquid chamber and the stroke simulator, and the one-system brake cylinder is connectable to the liquid chamber. A switching valve for selectively connecting a brake cylinder to the power chamber or the liquid chamber is provided.

According to a fifth aspect of the present invention, in the two-brake system, a hydraulic pressure source for generating hydraulic pressure, a reservoir for storing hydraulic fluid, a power piston for generating output,
A power chamber in which a pressure receiving surface of the power piston faces, and a power chamber that is disconnected from the hydraulic pressure source when not operating and communicates with the reservoir when not in operation. A control valve for introducing the hydraulic fluid from the hydraulic pressure source into the power chamber in accordance with the operation thereof, an input shaft for controlling the operation of the control valve, and an input being applied to operate the input shaft. A brake pedal, a master cylinder having a master cylinder piston that is operated and controlled by an output of the power piston to generate a master cylinder pressure, and a pressure conversion cylinder that generates a hydraulic pressure by introducing a hydraulic pressure in the power chamber. The brake cylinder of one system, which generates a braking force by introducing the hydraulic pressure of the pressure conversion cylinder, and the master cylinder of the master cylinder A brake chamber of the other system that generates a braking force by introducing a damping pressure, a liquid chamber provided between the power piston and the master cylinder piston, and sealed at least when the power piston is operated; A stroke simulator connected to the liquid chamber and configured to introduce the hydraulic fluid in the liquid chamber when the power piston is operated.

According to a sixth aspect of the present invention, an on-off valve is provided between the liquid chamber and the stroke simulator, and the pressure conversion cylinder is connectable to the liquid chamber. A switching valve for selectively connecting the power chamber to the power chamber or the liquid chamber.

Further, the invention according to claim 7 is characterized in that at least an orifice is provided between the liquid chamber and the stroke simulator. Claim 8
The invention is characterized in that a check valve is provided in parallel with the orifice to allow only the flow of the liquid from the stroke simulator to the liquid chamber.

[0019]

In the brake hydraulic booster according to any one of the first to eighth aspects of the present invention, the hydraulic fluid in the fluid chamber is introduced into the stroke simulator when the power piston is operated. Therefore, at this time, the stroke of the brake pedal is larger than the conventional pedal stroke by the amount of the working fluid absorbed by the stroke simulator. Especially,
The brake fluid pressure boosting system according to the third and fifth aspects of the present invention is a semi-full power brake system. In this semi-full power brake system, the pedal stroke increases, so that an appropriate pedal stroke is possible.

According to the second aspect of the present invention, when the on-off valve and the communication / shutoff control valve are respectively controlled so as to shut off both the stroke simulator and the second pressure receiving cylinder from the liquid chamber, the liquid chamber is locked. Even when the power piston operates, the working fluid in the liquid chamber does not flow out of the liquid chamber. Therefore, at this time, the stroke of the brake pedal does not increase or decrease, and the pedal stroke is equal to the stroke of the brake system such as the piston stroke of the brake cylinder to which the master cylinder pressure is introduced, as in the conventional case.

When the on-off valve and the communication / shutoff control valve are controlled so that the stroke simulator communicates with the liquid chamber and the second pressure receiving cylinder is shut off from the liquid chamber, the hydraulic fluid in the liquid chamber is actuated when the power piston operates. Is introduced only to the stroke simulator. Therefore, it is exactly the same as the case of the first aspect.

When the opening / closing valve and the communication / shutoff control valve are controlled so that the stroke simulator is shut off from the liquid chamber and the second pressure receiving cylinder is connected to the liquid chamber, when the power piston operates, the hydraulic fluid in the liquid chamber is Is introduced only into the second pressure receiving cylinder. Therefore, at this time, the stroke of the brake pedal is increased by the amount of the hydraulic fluid absorbed by the second pressure receiving cylinder. In this case, if the hydraulic fluid absorption amount of the second pressure receiving cylinder is set to be different from the hydraulic fluid absorption amount of the stroke simulator, the increase amount of the pedal stroke at this time becomes different from that of the stroke simulator.

When the on-off valve and the communication / shutoff control valve are controlled so that both the stroke simulator and the second pressure receiving cylinder communicate with the liquid chamber, when the power piston is operated, the hydraulic fluid in the liquid chamber becomes the stroke simulator and the second cylinder. 2 is received by both of the pressure receiving cylinders. Therefore, at this time, the stroke of the brake pedal is increased by the amount of the working fluid absorbed by the stroke simulator and the second pressure receiving cylinder, respectively. In this case, the amount of hydraulic fluid absorbed is the largest, so that the pedal stroke is the largest in comparison with other cases. in this way,
By appropriately controlling the on-off valve and the communication / shutoff control valve, the pedal stroke can be variously changed.

Further, in the invention of claim 4, the second pressure receiving cylinder of claim 2 is replaced with a brake cylinder of one system, and the communication / shutoff control valve is replaced with a switching valve. 2 is the same as the operation of 2.

In the invention of claim 6, the second pressure receiving cylinder of claim 2 is replaced with a pressure conversion cylinder, and the communication / shutoff control valve is replaced with a switching valve. Is the same as

Further, in the invention of claim 7, when the brake pedal is rapidly depressed and the brake is rapidly depressed, the power piston strokes rapidly to supply the hydraulic fluid in the fluid chamber to the stroke simulator. Since the supply of the hydraulic fluid to the stroke simulator is delayed due to the orifice effect, the pedal stroke becomes smaller than usual. At the same time, the fluid pressure in the fluid chamber becomes higher than usual by the delay of the supply of the working fluid to the stroke simulator. Therefore, at the time of sudden braking, the pedal stroke becomes smaller than usual and the hydraulic pressure of the liquid chamber also becomes higher, so that the sudden braking is effectively operated.

Further, according to the invention of claim 8, since the liquid supplied to the stroke simulator is returned to the liquid chamber without delay by the check valve, even if the orifice is provided, the master cylinder piston, the power piston And the input shaft returns to the inoperative position without delay.

[0028]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a first embodiment of a brake hydraulic booster according to the present invention, and FIG.
FIG. 2 is a partially enlarged sectional view of FIG.

As shown in FIGS. 1 and 2, the brake hydraulic booster 1 of the first embodiment has a master cylinder 2 provided integrally with the master cylinder 2 and a common housing 3. .

The housing 3 is provided with a stepped hole 4 which is relatively long in the axial direction and is opened at the right end in FIG. 1, and a small diameter portion 4a of the stepped hole 4 is provided with a brake having a constant sectional area. It extends from the hydraulic booster 1 to the master cylinder 2. The right end opening of the axial hole 4 is closed in a liquid-tight manner by a plug 6 having an O-ring 5. The plug 6 has a stepped cylindrical protrusion 6 a, and the small diameter protrusion 6 b of the stepped cylindrical protrusion 6 a is connected to the stepped hole 4 of the housing 3.
The large-diameter projection 6c of the stepped cylindrical projection 6a is press-fitted into the small-diameter portion 4a so as to be positioned within the small-diameter portion 4a, and the plug 6 is fixed by a nut 7 screwed to the housing 3. It is fixed to the housing 3 by being in contact with the step portion of the stepped hole 4.

A power piston 8 is disposed in the small diameter portion 4a of the stepped hole 4 in a liquid-tight and slidable manner. The power piston 8 is provided with a stepped hole 9 that is located at the center thereof, extends in the axial direction, and opens at the right end of the power piston 8. A small diameter portion 9 a of the stepped hole 9 has an end portion. A cylindrical valve seat member 10 having a first valve seat 10a is press-fitted. The flange 10b at the right end of the valve seat member 10 has a stepped hole 9
A large diameter portion 9 of the stepped hole 9.
The cylindrical fixing member 11 is axially supported by a cylindrical fixing member 11 fitted in the inside b. Further, the cylindrical fixing member 11 is fixed to the power piston 8 by a C ring 12.

In the small diameter portion 9a of the stepped hole 9, a collar 13 is provided.
A cylindrical valve element 15 integrally formed with a conical valve 14 is slidably disposed in the collar 13.
Is constantly urged in the direction of seating on the first valve seat 10a of the valve seat member 10. The axial hole 10c of the valve seat member 10
Inside, the second valve seat 1 formed at the tip of the valve operating member 17
7 a is disposed so as to be seated on the conical valve 14. Also,
The valve operating member 17 is fitted and fixed to the input shaft 18 and can abut on the valve operating member 17 at the tip of the small-diameter protruding portion 6b of the plug 6; Is integrally provided with a flange-shaped stopper portion 17b that defines the above. A spring 19 is contracted between the valve seat member 10 and the valve operating member 17,
The input shaft 18 is constantly biased rightward in the figure. The input shaft 18 penetrates the plug 6 in a liquid-tight manner, and its rear end is connected to a brake pedal (not shown).

A cylindrical reaction force piston 20 is slidably fitted between the input shaft 18 and each outer periphery of the valve operating member 17 and the inner periphery of the axial hole of the small diameter projecting portion 6b of the plug 6. Have been combined. As shown in FIG. 3, a first flange portion 20a and a second flange portion 20b are provided at the left end of the reaction force piston 20 in FIG. First flange 2
A stopper 17b can contact the left side of the valve operating member 17 with respect to the reaction piston 20 when the stopper 17b contacts the left side of the first flange 20a. The stopper portion 20c prevents further retreat. In other words, the valve operating member 1
7, the input shaft 18 is prevented from retreating further with respect to the reaction force piston 20 by the contact of the stopper portion 17b with the stopper portion 20c of the reaction force piston 20.

The right side of the second flange portion 20b is
When the reaction force piston 20 moves backward by a predetermined amount with respect to the power piston 8, the engagement portion 20d is engaged with the step portion 11a of the tubular fixing member 11. Furthermore, the reaction force piston 2
The right end 20 e of the “0” can contact the step 18 a of the input shaft 18. A spring 21 is provided between the second flange portion 20 b of the reaction force piston 20 and the cylindrical fixing member 11.
The spring 21 causes the second flange portion 20b of the reaction force piston 20 to normally contact the flange portion 10b of the valve seat member 10 by the spring 21.

Further, the housing 3 has an input port 22 into which the pressurized liquid is introduced, and the input port 22 and the small diameter portion 4 a of the stepped hole 4.
And a passage hole 23 communicating the
A passage hole 24 is formed in the power piston 8 to communicate the passage hole 23 with the small diameter portion 9 a of the stepped hole 9. In this case, the passage hole 24 is opened in the small diameter portion 9a between the valve seat member 10 and the collar 13. The input port 22 and the passage holes 23 and 24 constitute a hydraulic pressure supply passage.

A power chamber 25 is formed between the plug 6 and the right end of the power piston 8, and the power chamber 25 is always in communication with the axial hole 10 c of the valve seat member 10.
The stopper member 1 of the valve operating member 17 is provided in the power chamber 25.
7b and the first and second flange portions 20a and 20b of the reaction force piston 20 are located respectively. A gap is provided between the outer peripheral surface of the small diameter projecting portion 6b of the plug 6 and the inner peripheral surface of the cylindrical fixing member 11, so that the hydraulic fluid can freely flow on both axial sides of the cylindrical fixing member 11. It is possible to flow.

The power chamber 25 is always in communication with an output port 27 via a passage hole 26 formed in the housing 3, and the output port 27 is connected to a wheel in one of two brake systems. It is always in communication with the cylinders 28 and 29.

Further, the valve body 15 is provided with an axial hole 30 penetrating in the axial direction, and the axial hole 30 is always in communication with a passage hole 31 formed in the power piston 8. The passage hole 31 is formed in the housing 3 through the small diameter portion 4a.
The outlet 32 is always connected to a reservoir 33, and the outlet 32 is always connected to a reservoir 33. Furthermore,
The power chamber 25 has a passage hole 3 formed in the power piston 8.
4, it is always in communication with a chamber 35 facing the step portion 15 a of the valve element 15.

Further, a hydraulic circuit 36 connecting the input port 22 and the reservoir 33 has a hydraulic pump 38 driven by a motor 37 and a check valve 3 on the discharge side of the hydraulic pump 38.
9 and an accumulator 40 are provided respectively. The accumulator 40 always stores a predetermined pressure by the discharge pressure of the hydraulic pump 38.

Incidentally, the brake fluid pressure booster 1 of this embodiment
Is provided with a reaction force chamber 41 formed in the plug 6, and the step portion 18 a of the input shaft 18 and the right end 20 e of the reaction force piston 20 face the reaction force chamber 41. The reaction force chamber 41 has a radial hole 42 formed in the plug 6 and an annular space 4 between the housing 3 and the plug 6.
3. Through an axial hole 44 formed in the housing 3,
The control pressure inlet 45 is always in communication.

As shown in FIG. 1, the control pressure inlet 45 is
It is connected to a variable servo device 47 having a pressure switching valve 46 composed of a two-position three-way valve. This two-position three-way switching valve 4
Reference numeral 6 denotes a first position I at which the control pressure inlet 45 is connected to a hydraulic circuit 36 constantly communicating with the reservoir 33, and a brake which connects the control pressure inlet 45 to the output port 27 and the wheel cylinders 28, 29. The second position II connected to the liquid passage is set, and the liquid pressure of the output port 27, that is, the liquid pressure of the power chamber 25 becomes the set operating pressure in the normal state while being set to the first position I. At this time, switching control to the second position II is performed.

On the other hand, the master cylinder 2 is configured as a tandem master cylinder having a primary piston 48 'and a secondary piston 48 "which are set to the same effective pressure receiving area as the power piston 8 respectively. , A primary piston 48 ′ is provided integrally with the front end of the power piston 8.

An interval restricting rod 49 for restricting the interval between the pistons 48 ', 48 "projects and is fixed toward the master cylinder piston 48, and a retainer 50 is slidable in the axial direction on the interval restricting rod 49. The retainer 50 and the primary piston 4
A spring 51 is contracted between the front end 8 'and the retainer 50 so that the retainer 50 is always urged away from the primary piston 48'. Normally, the retainer 50 comes into contact with the head 49a of the interval regulating rod 49,
Further separation from the primary piston 48 'is restricted.

The secondary piston 48 "is constantly urged rearward (to the right in FIG. 1) by the spring force of the return spring 52, and its rear end is normally in contact with the retainer 50. The primary piston 48 ′ And a rear end of the secondary piston 48 ″ are provided with cup seals 53 and 54, respectively, and a liquid chamber 55 is defined in the small diameter portion 4a between the cup seals 53 and 54. . The two cup seals 53 and 54 are provided from outside the liquid chamber 55 passing through the cup seals 53 and 54, respectively.
The flow of the liquid into the inside is allowed, but the cup seals 53 and 54
The flow of the liquid from the liquid chamber 55 to the outside of the liquid chamber 55 is stopped.

The housing 3 is provided with a brake fluid compensation port 56 for the master cylinder, and the brake fluid compensation port 56 is always in communication with the reservoir 33.
And, in the inoperative position of the primary piston 48 ',
The cup seal 53 is connected to the discharge port 32 and the brake fluid compensation port 56.
Is located between. Therefore, when not operating, the fluid flows freely between the fluid chamber 55 and the brake fluid compensation port 56 in both directions. However, the power piston 8 moves forward and the cup seal 53 moves to the brake fluid compensation port 56. , The flow of the liquid from the liquid chamber 55 to the brake liquid compensation port 56 is blocked.

The secondary piston 48 "is fitted in the small diameter portion 4a of the stepped hole 4 of the housing 3 in one direction in a liquid-tight and slidable manner by a cup seal 57 provided at the front end thereof. .

In the small diameter portion 4a, a liquid chamber 58 is defined by a secondary piston 48 ", and the liquid chamber 58 is connected via an output port 59 to a wheel cylinder in the other of the two brake systems. Further, the secondary piston 48 "is provided with a radial hole 62 and an axial hole 63 communicating with the radial hole 62. A valve rod 65 provided with a valve 64 at the end penetrates the axial hole 63, and the valve rod 65 is formed in the housing 3 in a small diameter portion 4 a and a radial hole formed in the secondary piston 48 ″. The valve 64 can be abutted on a valve release rod 66 provided radially through the valve 62. Further, the valve 64 is constantly urged by a spring 67 in a direction of sitting on a valve seat 68. When the piston 48 "is in the inoperative position shown in the figure, the valve rod 65 comes into contact with the valve release rod 66, so that the valve 64 separates from the valve seat 68 against the spring force of the spring 67, and the reservoir 33 And the liquid chamber 58 are communicated with each other. Also, the secondary piston 4
When the 8 "advances, the valve 64 is seated on the valve seat 68 and the valve rod 65 separates from the valve release rod 66 due to the spring force of the spring 67, the reservoir 33 and the liquid chamber 58 are shut off, and the master cylinder pressure is reduced. Is to occur.

The effective pressure receiving area of the power piston 8, the effective pressure receiving area of the primary piston 48 ', and the effective pressure receiving areas of the front and rear ends of the secondary piston 48 "are all set to be equal.

Further, the housing 3 is provided with a reservoir 3 at all times.
3 is drilled, so that the axial hole 63 of the secondary piston 48 ″ is always connected to the reservoir 33 via the radial hole 62, the small diameter portion 4a, and the passage hole 69. ing.

The liquid chamber 55 is connected to a variable stroke device 71 via a connection port 70 of the housing 3. The variable stroke device 71 includes a piston 72, a cylinder 7
3, a stroke simulator 75 for securing a pedal stroke, an orifice 76 provided in a passage between the connection port 70 and the stroke simulator 75, and a bypass simulator provided to bypass the orifice 76. Check valve 77 that allows only the flow of liquid from stroke simulator 75 to connection port 70
It is composed of

The output port 2 of the brake hydraulic booster 1
A pump 38 and an accumulator 40 are provided in a liquid passage connecting the wheel cylinders 7 and one of the wheel cylinders 28 and 29.
A hydraulic pressure failure brake operating device 78 is provided for reliably operating the brake of one system when the hydraulic pressure source fails. The hydraulic pressure failure brake operating device 78 includes a pressure conversion cylinder 82 having a piston 79, a cylinder 80, and a spring 81, and a pressure control switching valve 83 including a two-position three-way valve.

The pressure conversion cylinder 82 corresponds to the second pressure receiving cylinder of the present invention. When the pressure fluid supplied from the power chamber 25 or the fluid chamber 55 is introduced, the piston 79 operates to increase the brake fluid pressure. Occurs and the wheel cylinders 28, 29
Has been introduced. When the hydraulic pressure failure is caused by the failure of the wheel cylinders 28 and 29, the pressure conversion cylinder 82
To prevent the hydraulic fluid from leaking out of the recess.

The pressure control switching valve 83 is connected to the accumulator 4
It is controlled by the pilot pressure based on the accumulated pressure of 0. In the pressure control switching valve 83, a first position I at which the pressure conversion cylinder 82 is connected to the output port 27 and a second position II at which the pressure conversion cylinder 82 is connected to the connection port 70 are set. When the pressure is normal, it is set to the first position I, and when the hydraulic pressure fails, it is switched to the second position II.

As described above, in the brake system using the brake hydraulic booster 1 integrated with the master cylinder 2 of the first example, one of the brake systems is provided with the hydraulic fluid in the power chamber 25 to its wheel cylinders 28 and 29. The brake system is configured as a semi-full power brake system in which a pressure is introduced, and the other brake system is a hydraulic brake system in which a master cylinder pressure is introduced into wheel cylinders 60 and 61 thereof.

Next, the operation of the brake hydraulic booster integrated with the master cylinder of this embodiment will be described. When the brake pedal is not depressed and the brake pedal is not depressed, the conical valve 1
4. First valve seat 10a of valve seat member 10 and valve operating member 1
The second valve seat 17a of No. 7 has a positional relationship shown in FIGS. That is, the conical valve 14 is seated on the first valve seat 10 a of the valve seat member 10, and the second valve seat 17 a of the valve operating member 17 is separated from the conical valve 14. In this state, the passage hole 24 constantly communicating with the input port 22 and the axial hole 10c of the valve seat member 10 are blocked, and the axial hole 10c of the valve seat member 10 and the discharge port 32 are always communicated. The valve body 15 communicates with the axial hole 30. Therefore, when the brake is not operated, the power chamber 25 is cut off from the pump 38 and the accumulator 40 and communicates with the reservoir 33, so that no pressure fluid is supplied to the power chamber 25.

The right end 20e of the reaction force piston 20 is
The input shaft 18 is separated from the step 18a. Further, the stopper portion 17b of the valve operating member 17 is in contact with the small-diameter projecting portion 6b of the plug 6 and the first
It is located at a position separated from the stopper portion 20c of the flange portion 20a and advanced from the stopper portion 20c. Further, the cup seal 53 of the primary piston 48 ′ is located behind the brake fluid compensation port 56, so that the fluid chamber 55 is connected to the reservoir 33.

On the other hand, in the master cylinder 2, the valve rod 65 is in contact with the valve opening rod 66, and the valve 64 is separated from the valve seat 68. Therefore, the liquid chamber 58 is connected to the reservoir 33.

Further, the pressure switching valve 4 of the variable servo device 47
6 is in the first position I shown in the drawing, and the reaction force chamber 41 is in the reservoir 3
It communicates with 3. Further, the pressure control switching valve 83 of the brake operating device 78 at the time of hydraulic pressure failure is in the first position I shown in the drawing,
The pressure conversion cylinder 82 is connected to the output port 27.

During normal brake operation by depressing the brake pedal, the input shaft 18 moves forward, the second valve seat 17a of the valve operating member 17 is seated on the conical valve 14, and the conical valve 14 is In this state, the passage hole 24 communicates with the axial hole 10c of the valve seat member 10 and the axial hole 10c of the valve seat member 10 and the axial hole 30 of the valve body 15 in this state. Is shut off. Therefore, the power chamber 25 is shut off from the reservoir 33 and communicates with the pump 38 and the accumulator 40, so that the pressurized liquid of the accumulator 40 is supplied to the power chamber 25. In this case, the conical valve 14, the first valve seat 10a and the second valve seat 1
The control valve 84 of the brake hydraulic booster 1 for selectively switching the power chamber 25 to the hydraulic pressure source of the pump 38 and the accumulator 40 or the reservoir 33 is constituted by 7a.

When the hydraulic pressure is introduced into the power chamber 25, the power piston 8 moves forward, and the reaction force piston 20 immediately operates, so that the right end 20e of the reaction piston 20 becomes the stepped portion 18 of the input shaft 18.
a. When the pressure fluid introduced into the power chamber 25 reaches a pressure that overcomes the spring force of the return spring 52, the power pressure causes the power piston 8 to generate an output, which causes the primary piston 48 'to move forward and the secondary piston 48' to advance. As the secondary piston 48 "advances, the valve 64 is seated on the valve seat 68, and a master cylinder pressure is generated in the liquid chamber 58.

The hydraulic pressure in the power chamber 25 is introduced into the two wheel cylinders 28 and 29 of one system, and the master cylinder pressure is introduced into the two wheel cylinders 60 and 61 of the other system. The brake operates. At this time, since the effective pressure receiving area of the power piston 8 on which the hydraulic pressure acts in the power chamber 25 is equal to the effective pressure receiving area of the master cylinder piston 44 which receives the master cylinder pressure in the liquid chamber 58, the hydraulic pressure in the power chamber 25 The pressure and the master cylinder pressure are balanced and equal. Therefore, the same hydraulic pressure is supplied to each wheel cylinder 28, 29; 60, 61.

The pressurized liquid in the power chamber 25 passes through the passage hole 34 in the axial direction.
Is introduced into the chamber 35 through the valve body 15, and the hydraulic pressure in the chamber 35 acts on the step portion 15 a of the valve body 15, whereby the valve body 15
Is urged in a direction opposing the hydraulic pressure of the power chamber 25.

When the primary piston 48 'moves forward and its cup seal 53 passes through the brake compensation port 56,
The liquid chamber 55 is shut off from the reservoir 33 to be in a sealed state. At this time, the primary piston 48 'advances more than the secondary piston 48 ", so that the liquid chamber 5
5 from the connection port 70, the variable stroke device 71
Is sent to the stroke simulator 75. At this time,
Since the primary piston 48 'moves forward at a normal speed during normal brake operation, the orifice effect of the orifice 76 on the liquid flowing to the stroke simulator is small. Therefore, the primary piston 48 '
That is, the power piston 8 is at a normal speed,
The stroke is performed by the amount corresponding to the stroke of 2, that is, the amount of the hydraulic fluid absorbed by the stroke simulator 75. Therefore, the pedal stroke during normal operation is a stroke amount based on the sum of the loss stroke of the wheel cylinders 60 and 61 and the hydraulic fluid absorption of the stroke simulator 75.

When the reaction force of the input shaft 18 becomes equal to the input of the input shaft 18, the conical valve 14 moves to the first valve seat 10 of the valve seat member 10.
a and the second valve seat 17 a of the valve operating member 17, and the power chamber 25 is shut off from both the accumulator 40 and the reservoir 33. When the input of the input shaft 18 further rises, the conical valve 14 is again separated from the first valve seat 10a, and the hydraulic fluid is further supplied to the power chamber 25, and the power chamber 2
The hydraulic pressure in 5 further increases. Thereafter, as the conical valve 14 repeats seating and unseating on the first valve seat 10a, the hydraulic pressure in the power chamber 25 increases as the input of the input shaft 18 increases. In this case, the brake hydraulic booster 1 performs servo control with a relatively small servo ratio of the servo ratio during normal braking.

During this servo control, the hydraulic pressure in the power chamber 25 does not increase to the operating pressure of the pressure switching valve 46 until the input reaches a predetermined level.
The reaction force chamber 41 remains in the reservoir 33
Is still connected to

And each wheel cylinder 28, 29;
Each of 60 and 61 generates a braking force boosted with respect to the input of the input shaft 18, and the brake is operated by this braking force. At this time, as described above, the hydraulic pressure in the power chamber 25 and the master cylinder pressure are balanced and equal to each other, and the braking forces generated by the wheel cylinders 33, 34;

When the input becomes a predetermined amount and the hydraulic pressure in the power chamber 25 reaches the operating pressure of the pressure switching valve 46, the pressure switching valve 46
Is switched and set to the second position II. Then, the reaction force chamber 41 is connected to the output port 27 and the brake operating device 7 at the time of hydraulic pressure failure.
The hydraulic pressure at the output port 27, that is, the hydraulic pressure at the power chamber 25 is introduced into the reaction force chamber 41 into the reaction force chamber 41. Then, the hydraulic pressure introduced into the reaction force chamber 41 is applied to a part of the right end 20 e of the reaction force piston 20 in contact with the step 18 a of the input shaft 18 in the same direction as the input applied to the input shaft 18. To work. Therefore, the input shaft 18
Then, the output of the brake fluid pressure booster 1 increases more than the input of the input shaft 18 during the servo control during normal braking. That is,
The brake hydraulic pressure booster 1 performs servo control for boosting and outputting the input of the input shaft 18 with a relatively large servo ratio. Thereby, each wheel cylinder 28, 29;
Reference numerals 60 and 61 each generate a braking force larger than the braking force during normal braking with respect to the input of the input shaft 18. As described above, the brake hydraulic booster 1 has the reverse two-stage servo characteristic of performing servo control at a servo ratio larger than the servo ratio at the time of normal braking when the input becomes larger than a predetermined value.

Further, when the input is increased and the hydraulic pressure in the power chamber 25 reaches the maximum set pressure stored in the accumulator 40, the hydraulic pressure in the power chamber 25 does not further increase, and the brake hydraulic booster 1 Ends the servo control with the large servo ratio, and becomes full load. Accordingly, thereafter, the output increase of the brake hydraulic pressure booster 1 does not boost the input increase.

When the brake pedal is released to release the brake operation, the input shaft 18 and the valve operating member 17 are both retracted to the right, and the second valve seat 17a of the control valve 84 is moved to the conical valve 1 position.
4, the pressure fluid in the power chamber 25 passes through the axial hole 10 c of the valve seat member 10, the gap between the conical valve 14 and the second valve seat 17 a, the axial hole 30 of the valve body 15, and the diameter. The reservoir 3 is provided through the direction hole 31, the small diameter portion 4 a of the stepped hole 4, and the discharge port 32.
It is discharged to 3. At this time, the input shaft 18 is largely retracted until the stopper portion 17b of the valve operating member 17 comes into contact with the stopper portion 20c of the reaction force piston 20, so that the second valve seat 17a is greatly opened from the conical valve 14 and the power chamber The pressure fluid in 25 is quickly discharged.

By discharging the pressurized liquid in the power chamber 25, the pressurized liquid in both wheel cylinders 28, 29 of one system is also quickly discharged to the reservoir 33 through the power chamber 25. Hydraulic pressure drops. On the other hand, due to the spring force of the return spring 52, the secondary piston 48 ", the primary piston 48 ', and the power piston 8 rapidly retract. At this time, the primary piston 48' is larger than the secondary piston 48" due to the spring force of the spring 51. The liquid supplied to the stroke simulator 75 is returned to the liquid chamber 55 without delay by the check valve 77. Therefore, even if the orifice 76 is provided, the primary piston 48 'and the power piston 8 And the input shaft 18 returns to the inactive position without delay.

When the secondary piston 48 "retreats,
The fluid pressure in the fluid chamber 58 and the fluid pressure in both wheel cylinders 60 and 61 of the other system are both reduced. When the valve rod 65 comes into contact with the valve opening rod 66, the valve 64 moves to the valve seat 6 with respect to the subsequent retraction of the secondary piston 48 ″.
8, the liquid chamber 58 is connected to the reservoir 33.
For this reason, the hydraulic fluid of both wheel cylinders 60 and 61 is also quickly discharged to the reservoir 33 through the fluid chamber 58, and the hydraulic pressure of both wheel cylinders 60 and 61 further decreases. As a result, the brakes of both systems are quickly released.

When the hydraulic pressure in the power chamber 25 falls below the set operating pressure of the pressure switching valve 46, the pressure switching valve 46 is moved to the first position I.
And the reaction force chamber 41 is connected to the reservoir 33. Therefore, the output of the brake hydraulic pressure booster 1 decreases at a low servo ratio of the normal brake with respect to the decrease of the input.

Input shaft 1 until brake release is almost completed
8 further retracts, the stopper portion 17 of the valve operating member 17
When b comes into contact with the distal end of the small diameter protruding portion 6b of the plug 6, the retreat of the input shaft 18 and the valve actuating member 17 is stopped, and both the input shaft 18 and the valve actuating member 17 are limited to retreat. However, the input shaft 18 and the valve operating member 17
When the retraction stops, the power piston 8, the reaction force piston 20, the conical valve 14, and the valve seat member 10 continue to retreat. Therefore, the stopper portion 1 of the valve operating member 17
7b is separated from the stopper portion 20c of the reaction force piston 20, and the conical valve 14 is connected to the second valve seat 1 of the valve operating member 17.
Approaching 7a.

When the right end of the power piston 8 abuts on the plug 6, the retraction of the power piston 8 is stopped, the secondary piston 48 "and the power piston 8 are in the inoperative position, and the brake is quickly and completely released. In this state, the cup seal 5 of the primary piston 48 '
Since the position 3 is located behind the brake fluid compensation port 56, the chamber 55 is connected to the reservoir 33 via the brake fluid compensation port 56.

In the inoperative position of the power piston 8, the conical valve 14 comes very close to the second valve seat 17a of the valve operating member 17, the gap between the conical valve 14 and the second valve seat 17a becomes extremely small, and the seat is seated. It is on the verge. Therefore, when the brake pedal is depressed, the input shaft 18 and the valve operating member 17 are depressed.
When the valve moves forward, the second valve seat 17a is immediately seated on the conical valve 14 and the conical valve 14 is connected to the first valve seat 1 of the valve seat member 10.
Leave immediately from 0a. That is, the loss stroke for performing the switching operation of the control valve 84 becomes extremely small, and the brake operates quickly.

In this way, the brake is quickly operated at the time of the brake operation, and the brake operation is quickly released at the time of the release of the brake operation, so that the brake fluid pressure generating device 1 becomes extremely responsive. Further, when the brake pedal is rapidly depressed to apply a sudden brake, the power piston 8 and the primary piston 48 'also advance rapidly, and the liquid in the liquid chamber 55 is rapidly supplied from the connection port 70 to the stroke simulator 75. However, because the orifice effect of the orifice 76 delays the supply of the liquid to the stroke simulator 75, the pedal stroke becomes smaller than usual. At the same time, the liquid pressure in the liquid chamber 55 increases by the amount of delay in the supply of the liquid to the stroke simulator 75. At this time, the secondary piston 48 ″,
Since the effective pressure receiving areas of the primary piston 48 'and the power piston 8 are the same, the hydraulic pressure of the power chamber 25 and the hydraulic pressure of the liquid chamber 58 are equal to the hydraulic pressure of the liquid chamber 55, and are higher than usual.

The high hydraulic pressure in the power chamber 25 is applied to the output port 2
7 is supplied to the pressure conversion cylinder 82, and the piston 79 of the pressure conversion cylinder 82 operates to generate a high brake fluid pressure.
8, 29, the wheel cylinders 28, 29 generate a large braking force. On the other hand, a high master cylinder pressure is introduced from the output port 59 to the wheel cylinders 60, 61, and the wheel cylinders 60, 61 generate a large braking force. In this way, at the time of sudden braking, the brake hydraulic booster 1 can generate a large braking force with a small pedal stroke by the orifice 76.

Thus, in the brake hydraulic booster 1 of the first example, the orifice 76 can change the pedal stroke in accordance with the depressing speed of the brake pedal, and when the brake pedal is rapidly depressed,
With the variable stroke device 71, the hydraulic booster 1 generates a large output with a small stroke of the input shaft 18, so that the braking force rises quickly and a large braking force can be generated quickly in both systems. Become like

Further, the pump 38 and the accumulator 4
When the hydraulic pressure of the hydraulic pressure source such as 0 fails, the pressure control switching valve 83
Is set to the second position II. In this state, even if the driver performs the normal brake operation by depressing the brake pedal to move the input shaft 18 forward and switch the control valve 84, no hydraulic pressure is introduced into the power chamber 25. For this reason, the power piston 8 does not operate depending on the hydraulic pressure of the power chamber 25.
Further, when the brake pedal is greatly depressed, the input shaft 18
Is greatly advanced, the valve operating member 17 makes a maximum stroke and contacts the valve seat member 10 to push the power piston 8. Then, the primary piston 48 'integrated with the power piston 8 advances, and its cup seal 53
Passes through the brake fluid compensation port 56, a fluid pressure is generated in the fluid chamber 55, and this fluid pressure is introduced into the pressure conversion cylinder 82 via the connection port 70 and the pressure control switching valve 83. The subsequent one-system brake operates in the same manner as in the case of the normal brake described above. The pedal stroke at this time is larger than the pedal stroke during normal operation by the loss stroke of the wheel cylinders 28 and 29.

Further, in the brake operation at the time of the hydraulic pressure failure, as the primary piston 48 'advances, the secondary piston 48 "also advances, and the valve 64 is seated on the valve seat 68 in the same manner as described above. A hydraulic pressure is generated in the liquid chamber 58. The hydraulic pressure in the liquid chamber 58 is introduced into the other system wheel cylinders 60 and 61 via the output port 59, and the other system brake is also operated. 4
Since the effective pressure receiving areas at the front and rear ends of the 8 ″ are equal, the liquid chamber 55
And the fluid pressure in the fluid chamber 58 becomes the same, and as a result, the braking force of both systems becomes the same.

The release of the brake operation at the time of hydraulic pressure failure is performed by releasing the brake pedal in the same manner as the release of the normal brake. When the brake pedal is released, the primary piston 4 and the power piston 8 are released.
8 'is retracted and the hydraulic pressure in the liquid chamber 55 is reduced, so that the braking force of one system is reduced, and the secondary piston 48 "is retracted and the hydraulic pressure in the liquid chamber 58 is reduced. Further, when the primary piston 48 'moves backward and the cup seal 53 passes through the brake compensation port 56, the liquid chamber 55 communicates with the brake compensation port 56. Then, the liquid chamber 55 is opened. Since the fluid communicates with the reservoir 33, the fluid pressure in the fluid chamber 55 and the pressure conversion cylinder 82 is discharged to the reservoir 33, so that the brake of one of the systems is completely released. As in the case of releasing the normal brake, the valve 64 is separated from the valve seat 68, so that the liquid chamber 58 communicates with the reservoir 33 and the brake of the other system is completely released. . In this way, in the brake hydraulic booster 1 of the first example, it is possible to reliably generate the braking force in both systems when the hydraulic pressure fails.

The orifice 76 and the check valve 77 are not always necessary, and may be omitted in some cases, for example, when the brake hydraulic booster 1 is provided with the function of sudden braking by another device.

FIG. 4 is a view similar to FIG. 1 showing a second embodiment of the present invention. The brake hydraulic booster 1 of the first example is the same as the variable servo apparatus 47 of the first example shown in FIG. 1 instead of the pressure switching valve 46 controlled by the hydraulic pressure of the power chamber 25 in the first example. An electromagnetic switching valve 85, which is a two-position three-way valve and is controlled by an electromagnetic force, is provided. A pressure sensor 86 for detecting the hydraulic pressure of the output port 27, that is, the hydraulic pressure of the power chamber 25 is provided near the output port 27.
Is provided. When the electronic control unit (not shown) detects that the hydraulic pressure of the power chamber 25 detected by the pressure sensor 86 has become equal to the operating pressure of the pressure switching valve 46, the electronic control unit 85 sets the electromagnetic switching valve 85 to the second position. Switch to position II.

Further, the variable stroke device 71 is connected to the connection port 70 via a first solenoid valve 87. The first electromagnetic opening / closing valve 87 has a communication position I and a shutoff position II, and is a normally open valve which is normally set to the communication position I. Further, the variable stroke device 71 includes a second solenoid on-off valve 88 provided in a passage connecting the connection port 70 and the pressure conversion cylinder 82. The second electromagnetic on-off valve 88 has a shut-off position I and a communication position II, and is a normally closed valve that is normally set to the shut-off position I. These first and second solenoid on-off valves 87, 88
Are both controlled by an electronic control unit.

The pressure control switching valve 83 in the hydraulic pressure failure brake operating device 78 of the first example is controlled to be switched by the accumulated pressure of the accumulator 40. Instead of the pressure control switching valve 83, the emergency brake operating device 78 is provided with an electromagnetic switching valve 89 made of the same two-position three-way valve and controlled by an electromagnetic force. A pressure sensor 90 for detecting the accumulated pressure of the accumulator 40 is provided in order to control the switching of the electromagnetic switching valve 89 when the hydraulic pressure has failed. When the electronic control unit determines that the accumulated pressure of the accumulator 40 has failed based on the detection signal from the pressure sensor 90, the electronic control unit switches the electromagnetic switching valve 89 to the second position II. Note that the electronic control unit switches the electromagnetic switching valve 89 to the second position II even when it determines that the automatic braking operation condition described later is satisfied.

Further, in the brake fluid pressure booster 1 of the second example, a brake fluid compensation port 56 is provided on the opposite side to the first example, and the brake fluid compensation port 56 is
It is connected to a liquid passage 91 branched from the hydraulic circuit 36. An automatic brake device 92 is provided in the liquid passage 91. The automatic brake device 92 includes an electromagnetic switching valve 93 composed of a two-position three-way valve and a pressure regulating valve 94. The electromagnetic switching valve 93 has a first position I where the brake fluid compensation port 56 is connected to the reservoir 33 and a second position II where the connection port 79 is connected to the accumulator 40 via the pressure regulating valve 94. Yes, usually 1st
It is set to the position I, and is switched to the second position II when the automatic brake is operated.
Another configuration of the brake hydraulic booster of the second example is the first example.
Same as the example.

The operation of the brake hydraulic booster 1 according to the second embodiment will be described. When the brake is not operated, the components of the brake hydraulic booster 1 and the master cylinder 2 are at the non-operating position shown in FIG. In this non-operation state, the state is exactly the same as in the case of the first example described above. Therefore, in this state, when the normal brake operation is performed by depressing the brake pedal at the normal speed, the brake hydraulic booster 1 performs the same operation as in the first example. Each of these solenoid valves 87, 88,
When all 89 are inactive, the pedal stroke
It is the same as the pedal stroke during normal operation in the example.

When only the first solenoid on-off valve 87 is operated and set to the shut-off position II, the liquid chamber 55 is shut off from the stroke simulator 75. Therefore, when the cup seal 53 of the primary piston 48 'advances beyond the brake fluid compensation port 56, the fluid chamber 55 is locked. At this time, the pedal stroke is the master cylinder 2
Only the stroke of the other system on the side of the secondary piston 48 ″.

Further, the first and second solenoid on-off valves 87, 8
8 and the solenoid-operated directional control valve 89 are both set to the position II, the pressure conversion cylinder 82 is disconnected from the power chamber 25 and connected to the liquid chamber 55, and the liquid chamber 55 is disconnected from the stroke simulator 75. Is done. At this time,
Pedal strokes are wheel cylinders 28, 29, 60,
That is 61 strokes.

Further, the second electromagnetic switching valve 88 and the electromagnetic switching valve 8
9 are set to the position II and the first solenoid on-off valve 87 is not operated, the pressure conversion cylinder 82 is disconnected from the power chamber 25 and connected to the liquid chamber 55, 55 is connected to the stroke simulator 75. Therefore, the pedal stroke at this time is larger than the pedal stroke during normal operation of the first example by the stroke of the wheel cylinders 28, 29.

As described above, by controlling the operation of each of the solenoid valves 87, 88, 89, the pedal stroke can be variously changed. Therefore, depending on the vehicle status such as the loading status, the brake status, or the driver, etc.
A more appropriate pedal stroke can be set.

Next, the automatic braking operation will be described. When the automatic brake operation condition is satisfied during traveling of the vehicle, the electronic control unit switches the two electromagnetic switching valves 89 and 93 to the second position II. Then, the pressure conversion cylinder 82 is shut off from the power chamber 25 and the connection port 70
And the brake fluid compensation port 56 is connected to the reservoir 33.
And is connected to the accumulator 40 via the pressure regulating valve 94. As a result, the accumulated pressure of the accumulator 40 is adjusted to a predetermined pressure by the pressure adjusting valve 94, and the adjusted hydraulic pressure is introduced into the hydraulic chamber 55 through the brake hydraulic compensation port 56, and the hydraulic pressure of the hydraulic chamber 55 is connected. Mouth 7
0 and is introduced into the stroke simulator 75 and into the pressure conversion cylinder 82. Then
The piston 79 operates to generate brake hydraulic pressure, and the generated brake hydraulic pressure is introduced into the wheel cylinders 28 and 29, and one of the brake systems operates.

On the other hand, the hydraulic pressure introduced into the liquid chamber 55 acts on the rear end face of the secondary piston 48 "of the master cylinder 2, so that the secondary piston 48" operates and the liquid chamber 58 is moved to the liquid chamber 58. A master cylinder pressure equal to the hydraulic pressure of 55 is generated. This master cylinder pressure is output port 59
To the wheel cylinders 60 and 61 to operate the brake of the other system. In this way, automatic braking is reliably activated in both systems.

When the condition for releasing the operation of the automatic brake is satisfied, the electronic control unit sets both the electromagnetic switching valves 89 and 93 to the first position I where the both are not activated again. Then, the pressure conversion cylinder 82 is disconnected from the connection port 70 and connected to the power chamber 25, and the brake fluid compensation port 56 is disconnected from the accumulator 40 and connected to the reservoir 33. As a result, the liquid pressure in the liquid chamber 55 is
Is discharged to the reservoir 33 through the power chamber 25, and the hydraulic pressure of the pressure conversion cylinder 82 passes through the power chamber 25.
Is discharged. Thereby, the brake fluid pressure of the pressure conversion cylinder 82 disappears, and the brake of one system is released.

When the liquid chamber 55 is connected to the reservoir 33 and its hydraulic pressure decreases, the secondary piston 48 "also moves backward, and when the secondary piston 48" returns to the non-operating position, the above-described normal brake is applied. Since the liquid chamber 58 communicates with the reservoir 33 in the same manner as in the case (1), the master cylinder pressure disappears and the brake of the other system is released. Thus, the automatic brake is completely released.

Further, in the hydraulic pressure failure brake operating device 78, when the hydraulic pressure of the accumulator 40 fails, the electronic control unit moves the electromagnetic switching valve 89 to the second position II according to a detection signal from the pressure sensor 90. Switch. Therefore,
This is exactly the same as the case of the first example described above, and the brake can be operated by depressing the brake pedal even when the hydraulic pressure fails. Other functions and effects of the brake hydraulic booster of the second example are the same as those of the first example.

In each of the above-described examples, the variable pressure cylinder 82 is provided. However, the variable pressure cylinder 82 is omitted, and the hydraulic pressure of the power chamber 25 and the hydraulic pressure of the hydraulic chamber 55 are directly controlled by the wheel cylinder 28, 29 can also be introduced. Further, the hydraulic fluid in the liquid chamber 55 can be directly introduced into the stroke simulator 75 by omitting the orifice 76.

Further, a primary piston 48 'of the master cylinder 2 is provided at the front of the power piston 8.
The front part of the power piston 8 does not need to function as the primary piston 48, but only needs to be able to supply the hydraulic fluid in the liquid chamber 55 from the connection port 70 when the power piston 8 is operated.

Further, in each of the above-described examples, the hydraulic booster of the present invention is applied to the brake hydraulic booster of the semi-full power brake system. The present invention can also be applied to a one-system or two-system brake system that operates a brake.

[0100]

As is apparent from the above description, according to the brake hydraulic booster system of the present invention, the stroke of the brake pedal can be variously changed as required. This makes it possible to set a more appropriate pedal stroke depending on the vehicle condition such as the loaded condition, the brake condition, or the driver.

In particular, according to the third and fifth aspects of the present invention,
In a semi-full power brake, an appropriate stroke can be set by changing the brake pedal stroke in various ways. Thereby, the driver does not feel uncomfortable when the brake is operated, and the brake operation feeling can be improved.

According to the seventh aspect of the present invention, the pedal stroke can be changed depending on the depressing speed of the brake pedal. Thus, for example, a large braking force can be obtained with a small pedal stroke at the time of sudden braking, and the sudden braking can be reliably operated.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first example of an embodiment of a brake hydraulic booster system according to the present invention.

FIG. 2 is a partially enlarged sectional view of the brake hydraulic booster shown in FIG.

FIG. 3 is a sectional view showing a reaction force piston used in the brake hydraulic booster shown in FIG. 1;

FIG. 4 is a sectional view showing a second example of the embodiment of the present invention.

FIG. 5 is a partial cross-sectional view partially showing a conventional brake hydraulic booster.

[Explanation of Signs] 1 ... Brake hydraulic booster, 2 ... Master cylinder, 3 ...
Housing, 8: Power piston, 18: Input shaft, 25
... Power room, 27,59 ... Output port, 28,29,60,61 ...
Wheel cylinder, 33 reservoir, 40 accumulator, 48 'primary piston, 48 "secondary piston, 55, 58 liquid chamber, 56 brake fluid compensation port, 70 connection port, 71 variable stroke device, 75
Stroke simulator, 76: orifice, 77: check valve, 78: brake operating device when hydraulic pressure fails, 8
2 ... pressure conversion cylinder, 83 ... pressure control switching valve, 84 ...
Control valve, 85, 93: electromagnetic switching valve, 86, 90: pressure sensor, 87: first electromagnetic on / off valve, 88: second electromagnetic on / off valve, 8
9: electromagnetic switching valve, 92: automatic brake device, 94: pressure regulating valve

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masahiro Shimada 2-11-6 Shinmeicho, Higashimatsuyama-shi, Saitama Automobile Equipment Co., Ltd. Matsuyama Plant (72) Inventor Mamoru Sawada 1-1-1 Showacho, Kariya-shi, Aichi Prefecture Address Denso Corporation

Claims (8)

[Claims] 1. A hydraulic pressure source for generating hydraulic pressure, a reservoir for storing hydraulic fluid, a power piston for generating an output, a power chamber facing a pressure receiving surface of the power piston, and a power chamber when not operating. The power chamber is shut off from the hydraulic pressure source and communicates with the reservoir, and the power chamber is shut off from the reservoir during operation and communicates with the hydraulic pressure source. A control valve to be introduced into the chamber, an input shaft for controlling the operation of the control valve, a brake pedal to which the input is applied to actuate the input shaft, and an operation controlled by an output of the power piston to generate a master cylinder pressure A master cylinder having a master cylinder piston, a brake cylinder that generates a braking force by introducing a master cylinder pressure of the master cylinder, A liquid chamber provided between a piston and the master cylinder piston and sealed at least when the power piston is operated, and connected to the liquid chamber;
A brake simulator comprising a pressure receiving cylinder into which the hydraulic fluid in the fluid chamber is introduced when the power piston is actuated. 2. An on-off valve disposed between the liquid chamber and the stroke simulator, and a second valve connected to the liquid chamber, wherein a hydraulic fluid in the liquid chamber is introduced when the power piston is operated. And the second pressure receiving cylinder and the liquid chamber are disposed between the second pressure receiving cylinder and the liquid chamber.
The brake hydraulic booster system according to claim 1, further comprising a communication / shutoff control valve for controlling the shutoff. 3. A two-brake brake system, comprising: a hydraulic pressure source for generating hydraulic pressure, a reservoir for storing hydraulic fluid, a power piston for generating output, a power chamber facing a pressure receiving surface of the power piston, When not operating, the power chamber is shut off from the hydraulic pressure source and communicates with the reservoir, and when operating, the power chamber is shut off from the reservoir and communicates with the hydraulic pressure source. A control valve introduced into the power chamber according to the operation, an input shaft for controlling the operation of the control valve, a brake pedal to which an input is applied to operate the input shaft, and an operation controlled by an output of the power piston. A master cylinder having a master cylinder piston for generating a master cylinder pressure, and a system brake for generating a braking force by introducing the hydraulic pressure of the power chamber. Brake cylinder, a brake cylinder of the other system that generates a braking force by introducing a master cylinder pressure of the master cylinder, and a power piston and the master cylinder piston. A brake fluid pressure boosting system comprising: a fluid chamber which is sometimes sealed; and a stroke simulator which is connected to the fluid chamber and in which the hydraulic fluid in the fluid chamber is introduced when the power piston is operated. 4. An on-off valve is provided between the liquid chamber and the stroke simulator, a brake cylinder of the one system is connectable to the liquid chamber, and the brake cylinder is connected to the power chamber. 4. The brake hydraulic booster system according to claim 3, wherein a switching valve for selectively switching connection is provided in the fluid chamber. 5. A two-brake brake system, comprising: a hydraulic pressure source for generating hydraulic pressure, a reservoir for storing hydraulic fluid, a power piston for generating output, a power chamber facing a pressure receiving surface of the power piston, When not operating, the power chamber is shut off from the hydraulic pressure source and communicates with the reservoir, and when operating, the power chamber is shut off from the reservoir and communicates with the hydraulic pressure source. A control valve introduced into the power chamber according to the operation, an input shaft for controlling the operation of the control valve, a brake pedal to which an input is applied to operate the input shaft, and an operation controlled by an output of the power piston. A master cylinder having a master cylinder piston for generating a master cylinder pressure, and a pressure conversion cylinder for generating a hydraulic pressure by introducing the hydraulic pressure in the power chamber. The brake cylinder of one system that generates a braking force by introducing the hydraulic pressure of the pressure conversion cylinder, and the brake cylinder of the other system that generates the braking force by introducing the master cylinder pressure of the master cylinder A liquid chamber provided between the power piston and the master cylinder piston and sealed at least when the power piston is operated, and a hydraulic fluid connected to the liquid chamber and operated in the liquid chamber when the power piston is operated. And a stroke simulator into which the hydraulic fluid is boosted. 6. An on-off valve is provided between the liquid chamber and the stroke simulator, the pressure conversion cylinder is connectable to the liquid chamber, and the pressure conversion cylinder is connected to the power chamber or the power chamber. 6. The brake hydraulic boosting system according to claim 5, wherein a switching valve for selectively switching connection is provided in the liquid chamber. 7. The brake hydraulic boosting system according to claim 1, wherein at least an orifice is provided between the liquid chamber and the stroke simulator. 8. A brake hydraulic boosting system according to claim 7, wherein a check valve is provided in parallel with said orifice to allow only a flow of liquid from said stroke simulator to said liquid chamber. .