JPH11240442A - Semi-full power brake system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably operate the full power brake system brake even at a loss or fall of the hydraulic pressure source in the semi-full power brake system. SOLUTION: When hydraulic pressure sources 37, 38, 40 are operating normally, hydraulic pressure to be introduced to a motor chamber 25 by brake operation is introduced to W/Cs 28, 29. Accordingly, the full power brake system brake is operated. A power piston 8 is operated by the hydraulic pressure of the motor chamber 25, and MCY2 generates MCY pressure. The MCY pressure is introduced to W/Cs 60, 61, and the MCY brake system brake is operated thereby. At loss or fall of the hydraulic pressure sources, a pressure switching control valve 83 is switched over. At brake operation, although no hydraulic pressure is introduced to the motor chamber 25, advancement of an input shaft 18 causes a hydraulic pressure generating piston 48' in a hydraulic chamber 55 to generate pressure. The hydraulic pressure is introduced to a pressure converting cylinder 27 that generates hydraulic pressure. The hydraulic pressure is then introduced to the W/Cs 28, 29. As a result, brakes of both systems are operated.

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 two-system hydraulic brake system provided with a brake hydraulic booster for boosting the brake pedal depression force with hydraulic pressure and outputting the boosted hydraulic pressure. The hydraulic pressure in the power chamber of the pressure booster is introduced into one of the brake cylinders, and the master cylinder (hereinafter also referred to as MCY) is activated by the output of the brake hydraulic booster that operates with the hydraulic pressure in the power chamber. By introducing the master cylinder pressure (hereinafter, also referred to as MCY pressure) generated by the MCY into the brake cylinder of the other system,
Each belongs to the technical field of a semi-full power brake device that operates a brake of each system.

[0002]

2. Description of the Related Art In a hydraulic brake device of an automobile,
Conventionally, a brake hydraulic booster that obtains a large braking force by boosting the pedal depression force with a hydraulic pressure has been often used, and a tandem master cylinder is operated by an output of the brake hydraulic booster, and MCY is operated. By introducing the MCY pressure generated by each of the pistons into two corresponding wheel cylinders (hereinafter also referred to as W / C), the brakes of both systems are operated.

FIG. 6 is a diagram schematically showing an example of a conventional hydraulic brake device provided with such a brake hydraulic booster. In the drawing, a is a brake hydraulic booster, b is a power piston of the brake hydraulic booster a, c is a control valve of the brake hydraulic booster a provided on the power piston b,
d is the power chamber of the brake hydraulic booster a, e is the hydraulic pressure supply passage of the brake hydraulic booster a, f is the hydraulic discharge passage of the brake hydraulic booster a, and g is the brake fluid storage and The reservoir to which the hydraulic pressure discharge passage f is connected, h is a reservoir g
Pump that sucks and discharges the brake fluid, i is the pump h
, J is an accumulator that stores the discharge pressure of the pump h and is connected to the hydraulic pressure supply passage e, k is an input shaft for switching control of the control valve c, m is a brake pedal connected to the input shaft k, n is MCY, o is the primary piston of MCYn (in the illustrated example, it is integral with the power piston b, but there is also a separate piston), p is the secondary piston of MCYn, and q is the first liquid chamber. , R is a second liquid chamber, s is a first return spring, t is a second return spring, u and v are W / C of one system connected to the first liquid chamber q, and w and x are second liquids. This is the W / C of the other system connected to the room r.

[0004] In this hydraulic brake device, when the brake is not operated, it is in the state shown in the figure, and the power chamber d is cut off from the hydraulic pressure supply passage e by the control valve c and is connected to the hydraulic pressure discharge passage f. I have. Therefore, the power chamber d is at atmospheric pressure. Both the primary piston o and the secondary piston p are in the inoperative position shown in the figure, and the first and second liquid chambers q and r are both connected to the reservoir g. Therefore, both the first and second liquid chambers q and r are at atmospheric pressure. Also, the pump h is driven by the motor i.
Is driven, and a predetermined pressure is always stored in the accumulator j.

In this state, when the brake pedal m is depressed and a brake operation is performed, the input shaft k moves forward and switches the control valve c. Thus, the power chamber d is shut off from the hydraulic pressure discharge passage f and is connected to the hydraulic pressure supply passage e. Then, the hydraulic pressure of the accumulator j is introduced into the power chamber d through the hydraulic pressure supply passage e.
The power piston b operates and moves forward due to the liquid pressure. Since the primary piston o advances due to the advance of the power piston b, the first liquid chamber q is shut off from the reservoir g to generate the MCY pressure. At the same time, M of the first liquid chamber q
Since the secondary piston p moves forward by the CY pressure,
The second liquid chamber r is also shut off from the reservoir g and generates MCY pressure. The respective MCY pressures of the first and second liquid chambers q, r are respectively introduced into W / Cu, v, w, x of each system, and the brake is operated.

When the depression of the brake pedal 2 is released, the input shaft k moves backward, the control valve c is switched, the power chamber d is cut off from the hydraulic pressure supply passage e, and is connected to the hydraulic pressure discharge passage f. . Then, due to the spring force of the first return spring s and the hydraulic pressure of the first hydraulic chamber q, the power piston b causes the hydraulic fluid in the power chamber d to pass through the hydraulic pressure discharge passage f to the reservoir g.
Retreat while discharging to. Due to the retraction of the power piston b, the primary piston o retreats and the hydraulic pressure of the first fluid chamber q decreases, and the secondary piston p is moved by the spring force of the second return spring t and the hydraulic pressure of the second fluid chamber r. The liquid pressure of the second liquid chamber r is reduced by retreating.

Power piston b, primary piston o
When the secondary piston p is retracted to the inoperative position, the power chamber d becomes atmospheric pressure, and the first and second
The liquid chambers q and r are both connected to the reservoir g, the atmospheric pressure is reached, and the brake is released.

In this hydraulic brake system, the hydraulic pressure sources of the pump h, the motor i and the accumulator j are lost, and the hydraulic pressure for operating the brake hydraulic booster a is not introduced. Also, by depressing the brake pedal m more than usual, the input shaft k directly pushes the power piston b, so that the primary piston o and the secondary piston p operate, and the first and second fluid chambers q, r The MCY pressure can be generated at the same time, and the brake can be reliably applied even if the hydraulic pressure source fails.

[0009]

By the way, the applicant of the present application has proposed a new hydraulic brake system as shown in FIG. 7 (the same components as those shown in FIG. 6 are denoted by the same reference numerals) as shown in FIG. In the brake, the power chamber d of the brake hydraulic pressure booster a is directly connected to W / Cu, v of one system, and the hydraulic pressure introduced into the power chamber d is changed to the W / Cu of one system.
A full-power brake system that is directly introduced into Cu, v to operate one of the brakes, and an MCY piston o of MCYn that is operated by the output of the brake hydraulic booster a (the primary piston o in FIG. A second liquid chamber r (hereinafter simply referred to as liquid chamber r) generated by the same reference numeral;
It goes without saying that the MCY pressure of the first liquid chamber q may be introduced into the W / Cw, x of the other system and the semi-full power brake device 1 including the MCY brake system for operating the brake of the other system. Proposal (Japanese Patent Application No. 8-3)
09214).

In the semi-full power brake device 1, since the hydraulic pressure in the power chamber d is directly introduced into the W / Cu, v of one system, when the same braking force is obtained, the stroke of the brake pedal m is reduced. MCY pressure W / of both systems
The size is smaller than that of a conventional general hydraulic brake device for introducing Cu, v, w, x.

However, in this semi-full power brake device, when the brake is operated, in the full power brake system, the hydraulic pressure of the accumulator j passes through the power chamber d,
Since it is introduced directly into one system W / Cu, v, if the hydraulic pressure source fails, the hydraulic pressure becomes W / Cu, v
It is conceivable that the brakes of one system do not operate.

The present invention has been made in view of such circumstances, and has as its object to provide a semi-full brake capable of reliably operating a brake of a full power brake system even if a hydraulic pressure source fails. It is to provide a power brake device.

[0013]

According to a first aspect of the present invention, there is provided a semi-full power brake device comprising a two-system semi-full power brake device, comprising: a hydraulic pressure source for generating hydraulic pressure; A reservoir for storing the hydraulic fluid, a power piston for generating an output, a power chamber facing a pressure receiving surface of the power piston, and a non-operating chamber that disconnects the power chamber from the hydraulic pressure source and communicates with the reservoir to operate. A control valve that shuts off the power chamber from the reservoir and communicates with the hydraulic pressure source to introduce the hydraulic fluid from the hydraulic pressure source into the power chamber according to its operation; and controls the operation of the control valve. An input shaft, a hydraulic pressure generating piston provided at a front end of the power piston, a liquid chamber in which hydraulic pressure is generated by the hydraulic pressure generating piston, and an operation controlled by the hydraulic pressure of the liquid chamber. A master cylinder piston that generates a master cylinder pressure, a brake cylinder of one system that generates a braking force by introducing the hydraulic pressure of the power chamber, and a braking force that is generated by the introduction of the master cylinder pressure The other system brake cylinder and the one system brake cylinder are connected to the power chamber when the hydraulic pressure source is normal, and the one system brake cylinder is connected to the hydraulic chamber when the hydraulic pressure source fails. And a pressure switching control valve connected to the control valve.

Further, the invention of claim 2 is characterized in that the pressure switching control valve comprises two normally open and normally closed on-off valves or one switching valve. Furthermore, the invention of claim 3 is characterized in that the pressure switching control valve is constituted by an electromagnetic valve.

Further, according to a fourth aspect of the present invention, there is provided a semi-full power brake system comprising two systems, a hydraulic pressure source for generating hydraulic pressure, a reservoir for storing hydraulic fluid, a power piston for generating output, and a power piston for generating power. A power chamber facing the pressure receiving surface of the power chamber, and shuts off the power chamber from the hydraulic pressure source and communicates with the reservoir when not operating, and shuts off the power chamber from the reservoir when operating and communicates with the hydraulic pressure source 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 a hydraulic pressure generating piston provided at a front end of the power piston. A hydraulic pressure is generated by the hydraulic pressure generating piston, and a hydraulic chamber constantly connected to the brake cylinder of the one system and an operation controlled by the hydraulic pressure of the hydraulic chamber are controlled. A master cylinder piston that generates a cylinder pressure, a brake cylinder of one system that generates a braking force by introducing the hydraulic pressure in the power chamber, and a braking force that is generated by the introduction of the master cylinder pressure. A brake cylinder of the other system,
A pressure switching control valve for connecting the one of the brake cylinders to the power chamber when the hydraulic pressure source is normal and disconnecting the one of the brake cylinders from the power chamber when the hydraulic pressure source fails. It is characterized by having.

Furthermore, the invention of claim 5 is characterized in that the hydraulic pressure of the power chamber or the hydraulic pressure of the liquid chamber is introduced into the one of the brake cylinders via a pressure variable cylinder. Further, the invention of claim 6 is characterized in that the variable pressure cylinder is disposed in parallel with the master cylinder.

[0017]

In the semi-full power brake system according to the present invention, the hydraulic pressure in the power chamber is controlled by the pressure switching control valve when the hydraulic pressure source is normal. And the MCY pressure of MCY is
It is introduced into the brake cylinder of the Y brake system, and the brakes of both systems operate.

When the hydraulic pressure source fails, the brake cylinder of the full power brake system is disconnected from the power chamber by the pressure switching control valve, and the hydraulic pressure between the hydraulic pressure generating piston at the front end of the power piston and the MCY piston is reduced. Connected to the room.
As a result, the hydraulic pressure generated in the liquid chamber by the hydraulic pressure generating piston is introduced into the brake cylinder of the full power brake system. Therefore, even when the hydraulic pressure source fails, MC
Not only the brake of the Y brake system operates, but also the brake of the full power brake system operates reliably.

According to the fourth aspect of the present invention, when the hydraulic pressure source is normal, the pressure switching control valve controls the hydraulic pressure in the power chamber and the hydraulic chamber between the hydraulic pressure generating piston at the front end of the power piston and the MCY piston. The generated hydraulic pressure is introduced into the brake cylinder of the full power brake system of one system, and the MCY pressure of MCY is introduced into the brake cylinder of the MCY brake system of the other system, and the brakes of both systems operate. . At this time, the fluid pressure in the fluid chamber is introduced into the brake cylinder of the full power brake system, so that the brake pressure rises quickly and the brake operates quickly. When the hydraulic pressure source fails, it is the same as the first aspect of the present invention.

Further, according to the fifth aspect of the invention, when the hydraulic pressure in the liquid chamber is introduced into the full power brake system when the hydraulic pressure source fails, the hydraulic pressure is directly applied to the brake cylinder of the full power brake system. Instead of being introduced, it is first introduced into the pressure conversion cylinder, whereby the hydraulic pressure generated by the pressure conversion cylinder is introduced into the brake cylinder of the full power brake system.

Therefore, when the brake pipe etc. on the brake cylinder side of the pressure switching control valve of the full power brake system is damaged and liquid leakage occurs, the pressure fluid in the liquid chamber is supplied to the full power brake system by the pressure conversion cylinder. Is prevented from leaking into the fluid chamber, so that the pressure fluid in the fluid chamber does not leak from the recess. As a result, even in this case, since the liquid pressure in the liquid chamber is ensured, the brake of the MCY brake system can be operated, and the brake function is ensured.

[0022]

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 semi-full power brake device according to the present invention, and FIG. 2 is a partially enlarged sectional view of FIG.

As shown in FIGS. 1 and 2, the semi-full power brake system of the first embodiment includes a brake hydraulic booster 1 and an MCY2. They are integrally formed by 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 MCY2. 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 6a.
The large-diameter projection 6c of the stepped cylindrical projection 6a is press-fitted into the small-diameter section 4a so that the small-diameter projection 6b of the a is located within the small-diameter section 4a of the stepped hole 4 of the housing 3. The plug 6 is fixed to the housing 3 by being in contact with the step of the stepped hole 4 by a nut 7 screwed to the housing 3.

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 each outer periphery of the input shaft 18 and 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. The right end 20e of the reaction force piston 20 is
At the time of non-operation, it is away from the step 18a of the input shaft 18, but
During operation, the input shaft 18 can contact the step 18a.

Further, the housing 3 has an input port 22 into which the pressurized liquid is introduced, and a small diameter portion 4 a of the input port 22 and 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 10c of the valve seat member 10.
The stopper member 1 of the valve operating member 17 is provided in the power chamber 25.
7b is located. Note that the small-diameter projection 6 of the plug 6
A gap is provided between the outer peripheral surface of b and the inner peripheral surface of the cylindrical fixing member 11 so that the working fluid can freely flow on both axial sides of the cylindrical fixing member 11.

The power chamber 25 is always in communication with an output port 27 through a passage hole 26 formed in the housing 3, and the output port 27 is connected to the W port in one of the two brake systems. / C28, 29 at all times.

Further, the valve body 15 is provided with an axial hole 30 penetrating in the axial direction. 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 passage hole 32 is always in communication with the reservoir hole 33. The passage hole 32 is always in communication with the reservoir 33. The axial hole 30, the passage hole 31, and the passage hole 32 are
A hydraulic pressure discharge passage for discharging the hydraulic pressure of No. 5 to the reservoir 33 is formed. Further, the power chamber 25 is always in communication with a chamber 35 facing the step portion 15a of the valve body 15 via a passage hole 34 formed in the power piston 8.

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.

By the way, the brake hydraulic 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 pressure switching valve 46 is
A first position I where the control pressure inlet 45 is connected to a hydraulic circuit 36 constantly communicating with the reservoir 33;
Is set to a second position II which is connected to a brake fluid passage connecting the output port 27 and the W / Cs 28 and 29, and is normally set to the first position I at the same time. When the pressure, that is, the fluid pressure in the power chamber 25 reaches the set operating pressure, the switching to the second position II is controlled.

On the other hand, the MCY 2 is a tandem MCY having a primary piston 48 ′ (corresponding to the hydraulic pressure generating piston of the present invention) and a secondary piston 48 ″ set to the same effective pressure receiving area as the power piston 8. In this case, the primary piston 48 'is provided integrally with the front end of the power piston 8.

An interval regulating rod 49 for regulating the interval between the pistons 48 ', 48 "is fixed so as to protrude toward the MCY piston 48.
, A retainer 50 is fitted slidably in the axial direction.
Further, a spring 51 is contracted between the retainer 50 and the front end of the primary piston 48 ', and the retainer 50 is constantly biased in a direction away from the primary piston 48'. Normally, the retainer 50 is in contact with the head 49a of the interval regulating rod 49, and is restricted from further moving away from the primary piston 48 '.

The secondary piston 48 "is always 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 MCY 2, and the brake fluid compensation port 56 is always in communication with the reservoir 33. When the primary piston 48 'is not operated, the cup seal 53 is located between the passage hole 32 and the brake fluid compensation port 56. 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. Passes through the fluid chamber 55 and the brake fluid compensation port 5
The flow of the liquid toward 6 is prevented.

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 W / W in the other of the two brake systems. C60, 61. The secondary piston 48 ″ further includes a radial hole 62 constantly communicating with the reservoir 33 and a radial hole 62.
An axial hole 63 communicating with the hole is formed. 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, when the secondary piston 48 ″ advances, the spring 67
The valve 64 is seated on the valve seat 68 and the valve rod 65 is separated from the valve release rod 66 by the spring force of, and the reservoir 33 and the liquid chamber 58 are shut off to generate MCY pressure.

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
7 is connected to the W / Cs 28 and 29 of one of the systems, a hydraulic pressure drop for reliably operating the brake of one of the systems when the hydraulic pressure source of the pump 38 and the accumulator 40 fails. An hour brake actuating device 78 is provided.
The hydraulic pressure failure brake operating device 78 includes a piston 7
9, a pressure conversion cylinder 82 having a cylinder 80 and a spring 81, and a pressure switching control valve 83 composed of a two-position three-way valve.

When the pressure fluid discharged from the power chamber 25 is introduced into the pressure conversion cylinder 82, the piston 79 operates to generate a brake fluid pressure, and this brake fluid pressure becomes W / C2
8, 29. Further, the pressure conversion cylinder 82 prevents the liquid discharged from the power chamber 25 from leaking out from the defective portion when the hydraulic pressure failure is due to the failure on the W / C 28, 29 side. It has become.

The pressure switching control 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 switching control 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.

Next, the operation of the brake hydraulic pressure booster integrated with the MCY of this embodiment will be described. When the brake is not operated when the brake pedal is not depressed, the conical valve 14, the first valve seat 10a of the valve seat member 10, and the second valve seat 17a of the valve operating member 17 are in the positional relationship shown in FIGS. . That is, the conical valve 14 is the first valve seat 1 of the valve seat member 10.
0a, and the second valve seat 17a 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 shut off,
The axial hole 10c of the valve seat member 10 communicates with the axial hole 30 of the valve body 15 which is always in communication with the passage hole 32. Therefore, when the brake is not operated, the power chamber 25 is
8 and the accumulator 40 are shut off and communicate with the reservoir 33, so that the pressurized liquid is not 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 a position where it contacts the small-diameter projecting portion 6b of the plug 6. Further, the cup seal 53 of the primary piston 48 'is
6, the liquid chamber 55 is connected to the reservoir 33.

On the other hand, in MCY2, the valve rod 65
Abuts against 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 switching control valve 83 of the brake operating device 78 at the time of hydraulic pressure failure is at the first position I shown in the drawing,
The pressure conversion cylinder 82 is connected to the output port 27.

At the time of 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 power piston 8 becomes the stepped portion 18 of the input shaft 18.
a.

When the pressure liquid 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, and the output causes the primary piston 48 'to move forward. ,
The secondary piston 48 "moves forward. With the advance of the secondary piston 48", the valve 64 is seated on the valve seat 68,
MCY pressure is generated in the liquid chamber 58.

Then, the hydraulic pressure in the power chamber 25 is introduced to both W / Cs 28, 29 of the full power brake system of one system, and the MCY pressure is supplied to both W / Cs 60, 60 of the MCY brake system of the other system. At 61, the brakes of both systems operate. At this time, the effective pressure receiving area of the power piston 8 to which the hydraulic pressure in the power chamber 25 acts is equal to the effective pressure receiving area of the MCY piston 44 to which the MCY pressure of the liquid chamber 58 receives. MCY pressure is balanced and equal. Therefore, each W / C 28, 29;
The hydraulic fluid having the same hydraulic pressure is supplied to both 0 and 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 fluid compensation port 56, the fluid 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 hydraulic fluid in the liquid chamber 55 flows from the connection port 70 through the variable stroke device 7.
It is sent to one stroke simulator 75. At this time, since the primary piston 48 'advances at a normal speed because of the normal brake operation, the orifice effect of the orifice 76 on the liquid flowing to the stroke simulator is small. Therefore, the primary piston 4
8 ', that is, the power piston 8 is at a normal speed and the stroke of the piston 72, that is, the stroke simulator 7
The stroke is made by the amount of the hydraulic fluid absorption of No. 5.

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

Then, each of the W / Cs 28, 29; 60, 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 MCY pressure are balanced and equal to each other, and each W / C 33,3
4: The braking forces generated by 68, 52 are also equal to each other.

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. As a result, the W / Cs 28, 29; 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.

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 inserted through the direction hole 31, the small diameter portion 4 a of the stepped hole 4 and the passage hole 32.
It is discharged to 3. At this time, since the input shaft 18 retreats greatly, the second valve seat 17a opens greatly from the conical valve 14,
The hydraulic fluid in the power chamber 25 is quickly discharged from the hydraulic discharge passage.

When the hydraulic fluid in the power chamber 25 is discharged, the hydraulic fluid in both W / Cs 28, 29 of one system is also quickly discharged to the reservoir 33 through the power chamber 25, and the two W / Cs 28, 29 are discharged.
Fluid 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. Although it comes to retreat, the stroke simulator 7
5 is returned to the liquid chamber 55 by the check valve 77 without delay, so that the orifice 76
Is provided, the primary piston 48 ', the power piston 8 and the input shaft 18 return to the inoperative position without delay. Also, the primary piston 4
In the case where a negative pressure is generated in the liquid chamber 55 at the time of the retreat of the liquid piston 8 ', the brake fluid in the reservoir 33 is supplied into the liquid chamber 55 through the passage hole 32 and the cup seal 53, so that the primary piston 48' The retreat is done smoothly.

When the secondary piston 48 "retreats,
The hydraulic pressure of the liquid chamber 58 and both W / Cs 60 and 61 of the other system
And the hydraulic pressure of both of them decreases. When the valve rod 65 comes into contact with the valve opening rod 66, the valve 64 is separated from the valve seat 68 with respect to the subsequent retraction of the secondary piston 48 ", and the liquid chamber 58 is connected to the reservoir 33. For this reason,
The hydraulic fluid of both W / Cs 60 and 61 is also quickly discharged to the reservoir 33 through the liquid chamber 58, and the hydraulic pressure of both W / Cs 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 drops 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 conical valve 14 approaches the second valve seat 17a of the valve operating member 17.

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.

When the brake pedal is rapidly depressed to apply a sudden brake, the power piston 8 and the primary piston 48 'also advance rapidly, so that the liquid in the liquid chamber 55 rapidly flows from the connection port 70 to the stroke simulator 75.
Sent to At this time, since the flow rate of the liquid from the connection port 70 is high, the orifice effect of the orifice 76 increases, and a high liquid pressure is generated in the liquid chamber 55. This liquid chamber 55
The high hydraulic pressure acts as a large reaction force on the input shaft 18 via the primary piston 48 'and the power piston 8, so that the pedal stroke is smaller than during normal braking. Therefore, the hydraulic booster 1 generates a large output due to the large reaction force, and the large output
Since the secondary piston 48 ″ of Y2 generates a high MCY pressure and the effective pressure receiving area of the secondary piston 48 ″ and the effective pressure receiving area of the power piston 8 are the same, the hydraulic pressure in the power chamber 25 decreases this MCY pressure. High hydraulic pressure equal to

The high hydraulic pressure in the power chamber 25 is applied to the output port 2
7 to the pressure conversion cylinder 82, the piston 79 of the pressure conversion cylinder 82 operates to generate a high brake fluid pressure, and this high brake fluid pressure is introduced into the W / Cs 28, 29, and the W / Cs 28, 29 Generates a large braking force. On the other hand, a high MCY pressure is applied to W / C6
0/61, the W / Cs 60 and 61 generate a large braking force. Thus, at the time of sudden braking, the brake hydraulic booster 1 can generate a large braking force by the orifice 76.

As described above, in the brake hydraulic booster 1 of the first example, the pedal stroke can be changed by the orifice 76 in accordance with the stepping speed of the brake pedal.
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
If the hydraulic pressure of the hydraulic pressure source such as 0 fails, the pressure switching control 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
When the input shaft 18 advances greatly, the input shaft 18 makes a maximum stroke and comes into contact with the power piston 8 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 the fluid pressure is introduced into the pressure conversion cylinder 82 via the connection port 70 and the pressure switching control 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
Since the liquid inside is also introduced into the stroke simulator 75, the stroke amount is based on the sum of the loss stroke of the W / Cs 28 and 29 and the stroke of the piston 72 of the stroke simulator 75.

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 W / C 60, 61 of the other system via the output port 59, and the brake of the other system also operates. Since the effective pressure receiving areas at the front and rear ends of the 48 ″ are equal, the hydraulic pressure of the liquid chamber 55 and the hydraulic pressure of the liquid chamber 58 become the same, and as a result, the braking force of both systems becomes the same.

Release of the brake operation at the time of hydraulic pressure failure is performed by releasing the brake pedal in the same manner as 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 'is retracted and the cup seal 53 passes through the brake fluid compensation port 56, the fluid chamber 55 communicates with the brake fluid compensation port 56. Then, the fluid chamber 55 is released. Communicates with the reservoir 33, so that the hydraulic pressure of the liquid 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, and the secondary piston 48 "further retreats. As in the case of the normal brake release, 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. .

As described above, in the brake hydraulic booster 1 of the first example, when the hydraulic pressure fails, the pedal stroke greatly changes so that the braking force can be reliably generated in both systems. Become.

In the first example, both the hydraulic pressure of the power chamber 25 and the hydraulic pressure of the liquid chamber 55 are introduced into the pressure conversion cylinder 82.
, It is only necessary to introduce at least the hydraulic pressure of the liquid chamber 55, and the hydraulic pressure of the power chamber 25 is
2 and can be directly introduced into the W / Cs 28 and 29.

Further, 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 has a function of sudden braking by another device.

FIG. 3 is a sectional view similar to FIG. 1, but showing a second embodiment of the present invention. The same components as those in the above-described first example are denoted by the same reference numerals, and a detailed description thereof will be omitted. (In the other examples described below, the same reference numerals are assigned to the same components as those in the earlier examples.) The same is true).

As shown in FIG. 3, in the semi-full power brake device of the second example, the variable servo device 47 and the variable stroke device 71 in the first example described above are omitted. Similarly, components related only to these devices 47 and 71, such as the reaction force chamber 41, the radial hole 42, the annular space 43, the axial hole 44, and the control pressure inlet 45, are also omitted.

The axial hole 30 and the passage hole 31 which are provided in the first example and are part of the hydraulic pressure discharge passage for discharging the pressurized liquid in the power chamber 25 to the reservoir 33,
In this second example, the hydraulic pressure discharge passage is omitted, and instead, a passage hole 85 formed in the valve operating member 17 and the input shaft 1
8, an annular space 87 between the input shaft 18 and the plug 6, a radial hole 8 formed in the plug 6.
8, an annular space 89 between the housing 3 and the plug 6, and an axial hole 90 formed in the housing 3 so as to always communicate with the reservoir 33. The passage hole 32 of the second example functions as a supply hole for supplying the liquid to the liquid chamber 55.

Further, the control valve 84 in the first example has the conical valve 14, but the control valve 84 in the second example has the ball valve 14 '. Further, the pressure conversion cylinder 82 of the second example has exactly the same configuration as the secondary side portion of the MCY 2, and a secondary piston 48 ″ is formed in a hole 91 formed in the housing 3 in parallel with the stepped hole 4. The piston 92 has exactly the same structure as the piston 92. That is, the pressure conversion cylinder 82 is provided in one housing 3 in parallel with the MCY2.

At both ends of the piston 92, cup seals 93, 94 are provided, respectively, so that the piston 92 can be slid in the hole 91 in one direction only in a liquid-tight manner. Mated as possible. In the hole 91, liquid chambers 95 and 96 facing both end surfaces of the piston 92 are defined. One liquid chamber 95 is provided with W / W in the other of the two brake systems.
The other liquid chamber 96 is always connected to the pressure switching control valve 83 while being constantly connected to C60 and C61.

Further, a radial hole 97 constantly communicating with the reservoir 33 and an axial hole 98 communicating with the radial hole 97 are formed in the piston 92. This axial hole 98 has a valve rod 10 provided with a valve 99 at the tip.
The valve rod 100 has a hole 91 in the housing 3 and a radial hole 9 formed in the piston 92.
7 can be brought into contact with a valve release rod 101 provided radially therethrough. Further, the valve 99 is connected to the spring 10
2 is always urged in the direction of sitting on the valve seat 103.

Further, the piston 92 is constantly urged rearward by the spring force of the return spring 104, and its rear end is normally in contact with the housing 3 at the bottom of the hole 91 during non-operation.

When the piston 92 is at the non-operating position shown in the figure, the valve rod 100 comes into contact with the valve release rod 101, so that the valve 99 separates from the valve seat 103 against the spring force of the spring 102. In addition, the reservoir 33 and the liquid chamber 95 are communicated with each other. When the piston 92 moves forward, the valve 99 is seated on the valve seat 103 by the spring force of the spring 102, the valve rod 100 is separated from the valve release rod 101, and the reservoir 33 and the liquid chamber 95 are shut off. Is caused to occur.

Further, the pressure switching control valve 83 of the second example is provided in the housing 3. Therefore, this second
In the example, the output port 27 and the connection port 70 in the first example are omitted. Other configurations of the semi-full power brake device of the second example are the same as those of the first example.

In the second example constructed as described above, when the normal brake is not operated, the piston 92 of the pressure conversion cylinder 82 is in the inoperative position shown in the figure, and the valve 99 is set to the valve seat similarly to the secondary part of the MCY2. The liquid chamber 95, that is, the W / C 60, 61 is in communication with the reservoir 33 through a gap between the valve 99 and the valve seat 103, an axial hole 98, and a radial hole 97. The state of the other components in the second example when the normal brake is not operated is the same as that in the first example.

During normal brake operation, hydraulic pressure is introduced into the power chamber 25 as in the first example described above. When the power piston 8 and the primary piston 48 'move forward and pass through the brake fluid compensation port 56 due to the fluid pressure in the power chamber 25,
When the liquid chamber 55 is sealed and a hydraulic pressure is generated,
The secondary piston 48 ″ advances by the hydraulic pressure of the liquid chamber 55,
MCY pressure is generated in the liquid chamber 58, and the MCY pressure is introduced into the W / Cs 60 and 61 of the other system, and the brake of the other system is operated. In this case, in the second example, the liquid chamber 55 is not connected to the variable stroke device 71, and the liquid chamber 55
After the liquid chamber 55 is sealed, the distance between the primary piston 48 'and the secondary piston 48 "does not change, and the pedal stroke does not include the variable stroke device 71. The pedal stroke is the same as that of the hydraulic booster.

On the other hand, the fluid pressure in the power chamber 25 is simultaneously introduced into the fluid chamber 96 of the pressure conversion cylinder 82 via the passage hole 26 and the pressure switching control valve 83. Then, the piston 92
Moves forward, and the valve 99 is seated on the valve seat 103 similarly to the secondary part of the MCY2, and the liquid chamber 95, that is, the W / C 60, 61
Is shut off from the reservoir 33. For this reason, a hydraulic pressure is generated in the liquid chamber 95, and this hydraulic pressure is applied to the W / C 28,
29, one of the brakes is activated.
At this time, the power piston 8 and the secondary piston 4
8 "and the pressure receiving area of the piston 92 are equal, so that the braking force of both systems is also equal.

When the hydraulic pressure fails, the pressure switching control valve 83 is switched to the second position II as in the first embodiment, the liquid chamber 96 of the pressure conversion cylinder 82 is shut off from the power chamber 25, and the liquid chamber 96 is closed. 55. In this state, when the brake pedal is depressed, the power piston 8 and the primary piston 48 'advance by the pedal depression force, and a hydraulic pressure is generated in the liquid chamber 55, and the hydraulic pressure is transmitted through the pressure switching control valve 83 to the liquid chamber 55. 9
6 is introduced. As with normal braking,
The piston 92 moves forward by the liquid pressure in the liquid chamber 96 and
The secondary piston 48 ″ moves forward due to the liquid pressure in the liquid chamber 55, and a liquid pressure is generated in the liquid chamber 58.
The liquid pressures of these liquid chambers 96, 58 are respectively W / C28,
29; 60, 61, the brakes of both systems operate.

By the way, in the semi-full power brake device of the second example, since the pressure conversion cylinder 82 is provided in parallel with MCY2, it does not largely protrude in the direction orthogonal to MCY2, but in the direction orthogonal to MCY2 as a whole. It can be formed compact. This second
Other operational effects of the example semi-full power brake device are the same as those of the first example.

FIG. 4 is a diagram schematically showing a third example of the embodiment of the present invention. As shown in FIG. 4, in the semi-full power brake device of the third example, the pressure switching control valve 83 and the pressure conversion cylinder
As in the example, both are provided outside the housing 3 and have exactly the same configuration as the pressure switching control valve 83 and the pressure conversion cylinder 82 of the first example. The other configuration of the semi-full power brake device of the third example is the same as that of the second example except that the reaction piston 20 is not provided.

The operation and effect of the semi-full power brake device of the third example are the same as those of the first example regarding the pressure switching control valve 83 and the pressure conversion cylinder 82, and the other effects are the same as those of the second example ( The pressure switching control valve 83
Is the same as in the second example).

FIG. 5 is a diagram schematically showing a fourth example of the embodiment of the present invention. As shown in FIG. 5, in the semi-full power brake device of the fourth example, both the pressure switching control valve 83 and the pressure conversion cylinder 82 in the third example described above are eliminated, and the normally-open pressure switching control valve is used instead. Is provided in a passage connecting the power chamber 25 and the W / Cs 28 and 29. The on-off valve 105 is in the open position I
And the closed position II are set. When the hydraulic pressure source is normal, the open position I is set, and when the hydraulic pressure source fails, the closed position II is set.
Is set to be switched. In the fourth example, the liquid chamber 55 is always connected to the W / Cs 28 and 29. Other configurations of the semi-full power brake device of the fourth example are the same as those of the third example.

In the semi-full power brake device of the fourth example thus configured, when the hydraulic pressure source is normal, the on-off valve 105 is set to the open position I. The hydraulic pressure is introduced directly into the W / Cs 28 and 29 through the on-off valve 105. At this time,
The hydraulic pressure generated in the liquid chamber 55 when the power piston 8 and the primary piston 48 ′ are advanced by the hydraulic pressure in the power chamber 25 is also directly introduced into the W / Cs 28 and 29. Therefore, the brake pressures of the W / Cs 28 and 29 increase quickly, and the power piston 8, the primary piston 48 ', and the secondary piston 48 "have the same pressure receiving area, so that the W / C 6
The brake pressure of 0.61 also increases quickly so as to be equal to the brake pressure of W / C 28,29.

When the hydraulic pressure source fails, the on-off valve 105 is switched to the closed position II. The liquid pressure in the liquid chamber 55 is directly W / C2
8, 29. Other functions and effects of the fourth example are the same as those of the third example.

In the fourth embodiment, the hydraulic pressure of the power chamber 25 or the hydraulic pressure of the liquid chamber 55 is directly introduced into the W / Cs 28 and 29. Can also be introduced via

In the passage from the liquid chamber 55 of the fourth embodiment, a normally-closed on-off valve which is switched and controlled by the pilot pressure from the accumulator 40 to close when the hydraulic pressure source is normal and to open when the hydraulic pressure source fails. Can be arranged side by side with the normally open on-off valve 105.

Further, in each of the above-described examples, the pressure switching control valve 8
3 and the on-off valve 105 are controlled by using the hydraulic pressure of the accumulator 11 as a pilot pressure. The pressure switching control valve 83 and the on-off valve 105 are constituted by solenoid valves, and the pressure of the accumulator 11 is detected. A pressure sensor may be provided, and the solenoid valves 83 and 105 may be switched and controlled directly or by an electronic control device based on a pressure detection signal from the pressure sensor.

[0099]

As is apparent from the above description, according to the semi-full power brake device of the first to fifth aspects, when the hydraulic pressure source fails, the brake cylinder of the full power brake system is powered by the pressure switching control valve. It is connected to the fluid chamber between the fluid pressure generating piston at the front end of the power piston and the master cylinder piston, and the fluid pressure generated in this fluid chamber by the advance of the fluid pressure generating piston is controlled by the full power brake system. In this case, not only the brake of the MCY brake system can be operated even when the hydraulic pressure source fails, but also the brake of the full power brake system can be reliably operated.

In particular, according to the invention of claim 4, when the hydraulic pressure source is normal, both the hydraulic pressure of the power chamber and the hydraulic pressure of the hydraulic chamber are introduced into the brake cylinder of the full power brake system by the pressure switching control valve. As a result, the brake pressure can be quickly increased in a normal state, and the brake can be operated quickly.

Further, according to the fifth aspect of the invention, when the hydraulic pressure source fails, the pressure conversion cylinder is operated by the hydraulic pressure generated by the advance of the liquid chamber generating piston, and the hydraulic pressure generated by the hydraulic pressure of the pressure conversion cylinder is generated. Is introduced into the full power brake system brake cylinder, so if the brake cylinder side from the full power brake system pressure switching control valve is leaking due to failure of the brake piping etc.,
The pressure fluid in the fluid chamber between the fluid pressure generating piston and the master cylinder piston can be prevented from leaking to the brake cylinder side of the full power brake system by the pressure conversion cylinder.
Therefore, the generation of the hydraulic pressure by the hydraulic pressure generation piston can be ensured, so that even in this case, the brake of the MCY brake system can be reliably operated, and the brake function can be ensured.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first example of an embodiment of a semi-full power brake device according to the present invention.

FIG. 2 is a partially enlarged sectional view of the first example shown in FIG.

FIG. 3 is a sectional view similar to FIG. 1, showing a second example of the embodiment of the present invention.

FIG. 4 is a diagram schematically showing a third example of the embodiment of the present invention.

FIG. 5 is a diagram schematically showing a fourth example of the embodiment of the present invention.

FIG. 6 is a diagram schematically showing a conventional two-system hydraulic brake device including a hydraulic booster and a tandem master cylinder.

FIG. 7 is a diagram schematically showing a semi-full power brake device according to the prior application.

[Explanation of symbols]

1. Brake hydraulic booster 2. Master cylinder 3.
Housing, 8: Power piston, 18: Input shaft, 25
... power room, 28,29,60,61 ... wheel cylinder,
33 ... reservoir, 37 ... motor, 38 ... pump, 40 ...
Accumulator, 48 ': Primary piston (hydraulic pressure generating piston), 48 ": Secondary piston, 55,5
8, 95, 96 ... liquid chamber, 56 ... brake fluid compensation port, 71 ...
Variable stroke device, 78: Brake operating device when hydraulic pressure fails, 79: Piston, 80: Cylinder, 81: Spring, 82: Pressure conversion cylinder, 83: Pressure switching control valve,
84 control valve, 92 piston, 99 valve

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Mamoru Sawada 1-1-1, Showa-cho, Kariya-shi, Aichi Pref. DENSO Corporation

Claims (6)

[Claims] 1. A semi-full power brake system comprising two systems, a hydraulic pressure source for generating a hydraulic pressure, a reservoir for storing hydraulic fluid, a power piston for generating an output, and a power facing a pressure receiving surface of the power piston. And a chamber, which shuts off the power chamber from the hydraulic pressure source when not operating and communicates with the reservoir, and shuts off the power chamber from the reservoir when operating and communicates with the hydraulic pressure source, and A control valve for introducing a hydraulic fluid into the power chamber in accordance with the operation thereof, an input shaft for controlling the operation of the control valve, a hydraulic pressure generating piston provided at a front end of the power piston, and a hydraulic pressure generating piston. A fluid chamber in which a fluid pressure is generated, a master cylinder piston that is operated and controlled by the fluid pressure in the fluid chamber to generate a master cylinder pressure, and a fluid pressure in the power chamber are introduced. A brake cylinder of one system that generates a braking force, a brake cylinder of the other system that generates a braking force when the master cylinder pressure is introduced, and a brake cylinder of the one system when the hydraulic pressure source is normal. A semi-full power brake device comprising: a cylinder connected to a power chamber; and a pressure switching control valve connecting the one of the brake cylinders to the liquid chamber when the hydraulic pressure source fails. 2. The semi-full power brake device according to claim 1, wherein said pressure switching control valve comprises two normally open and normally closed on-off valves or one switching valve. 3. The semi-full power brake device according to claim 1, wherein the pressure switching control valve is constituted by an electromagnetic valve. 4. A semi-full power brake system comprising two systems, comprising: 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 according to the operation thereof; An input shaft, a hydraulic pressure piston provided at the front end of the power piston, and a hydraulic chamber in which hydraulic pressure is generated by the hydraulic pressure piston and which is always connected to the one of the brake cylinders. A master cylinder piston that is operated and controlled by the hydraulic pressure of the liquid chamber to generate a master cylinder pressure, a brake cylinder of one system that generates a braking force by introducing the hydraulic pressure of the power chamber, A brake cylinder of the other system that generates a braking force by introducing a cylinder pressure, and a brake cylinder of the one system when the hydraulic pressure source is normal While connected to the power chamber, the liquid semi-full power braking system, characterized in that the brake cylinders of the one system is equipped with a pressure switch control valve to cut off from the power chamber upon failure of the pressure source. 5. The semi-full power brake device according to claim 1, wherein at least the hydraulic pressure of the liquid chamber is introduced into the one of the brake cylinders via a variable pressure cylinder. . 6. The variable pressure cylinder according to claim 5, wherein the variable pressure cylinder is disposed in parallel with the master cylinder.
The described semi-full power brake device.