JPH0920227A - Servo assysted brake system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the brake fluid pressure of a master cylinder in the failure of a power source, and prevent the brake fluid pressure from unnecessarily increasing when the power source is normal. SOLUTION: When a brake is operated in the normal state of a pump 4, a master cylinder is operated by the output of a fluid pressure assistor to generate a large brake fluid pressure, and the brake cylinder operates the brake by this brake fluid pressure. Since the operating fluid pressure acts on a valve closing piston 54, and a shutoff valve 52 is closed by the valve closing piston 54, a chamber 35 is laid into sealed state. Therefore, a stepped piston 36 becomes inoperable, and a brake fluid pressure intensifying valve 8 never performs power intensifying action. When the pump 4 fails, since no operating fluid pressure act on the valve closing piston 54, and a valve opening piston 56 opens the shutoff valve 52, the chamber 35 is laid into opened state. Therefore, the stepped piston 36 becomes operable, and the brake fluid pressure intensifying valve 8 performs the power intensifying action.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake booster system for generating a large brake force by hydraulic pressure, and more particularly, a brake hydraulic pressure for generating a sufficiently large brake hydraulic pressure even when the hydraulic pressure is lost due to a pressure source. The present invention relates to a brake booster system which has pressure increasing means and prevents the brake fluid pressure increasing means from operating unnecessarily when the hydraulic pressure by a pressure source is normal.

[0002]

2. Description of the Related Art For example, in an automobile, when a large braking force that cannot be obtained only by the driver's brake pedal force is required, or when the driver's brake pedal force is reduced, vacuum, compressed air or A brake booster system is used in which a large braking force can be obtained by using a pressure such as a hydraulic pressure.

By the way, in such a brake booster system, when the fluid pressure of the pressure source fails, there is a possibility that a sufficient braking force cannot be obtained. For this reason, when the pressure source fails, the operating force of the brake operating member must be made much larger than in the normal case. Therefore, there has been proposed a brake booster system capable of obtaining a relatively large braking force even with a normal brake operating force when the pressure source fails. Among such brake booster systems, there is one disclosed in Japanese Patent Publication No. 6-29011 as an example of a brake booster system using a hydraulic booster.

FIG. 11 is a diagram showing the brake booster system disclosed in this publication. In the figure, 131 is a brake booster system, 132 is a brake pedal, 133 is a hydraulic booster, 134 is a master cylinder, 135 is a wheel cylinder, 136 is a pump, 137 is an accumulator, 138 is a pressure booster, 139 is a pressure boosting piston, 140 is an on-off valve.

As shown in FIG. 11, a booster piston 139 is provided.
Is a stepped piston, and the master cylinder pressure acts on the pressure receiving surface on the left side of the large diameter portion, and the pressure booster 133 has a hydraulic pressure chamber (not shown) on the pressure receiving surface on the right side. Hydraulic pressure is applied.

When the brake is not operated, the booster piston 13
9 is at the position shown, and the open / close valve 140 is open. When the brake pedal 132 is depressed when the pressure source is normal, the control valve (not shown) of the hydraulic booster 133 is switched and the hydraulic fluid flows into the hydraulic fluid chamber (not shown) of the hydraulic booster 133. , A power piston (not shown) advances. As a result, the master cylinder 134 generates brake fluid pressure, and this brake fluid pressure is sent to the pressure booster 138.
Further, it is supplied to the wheel cylinder 135 through the open / close valve 140 that is open, and the wheel cylinder 135 operates to operate the brake. At this time, the brake hydraulic pressure of the master cylinder 134 acts on the left large diameter portion pressure receiving surface and the right small diameter portion pressure receiving surface of the pressure boosting piston 139 of the pressure booster 138, and the hydraulic booster 133 operates on the right side step pressure receiving surface. Since the hydraulic pressure of the hydraulic chamber acts, the pressure boosting piston 139 does not move. Therefore, the on-off valve 140 is kept open, and the brake fluid pressure of the master cylinder 134 is supplied to the wheel cylinder 135 as it is without being boosted by the booster 138.

When the pressure source fails, the brake pedal 13
Even if you depress 2, the hydraulic fluid does not flow into the hydraulic chamber,
No hydraulic pressure rises in the hydraulic chamber. The power piston does not advance depending on the hydraulic fluid. By further depressing the brake pedal 132, the power piston moves forward by the pedal effort. As a result, the master cylinder 134 generates a brake fluid pressure, the brake fluid pressure is supplied to the pressure booster 138, and is further supplied to the wheel cylinder 135 through the open / close valve 140 that is open. At this time, the brake fluid pressure of the master cylinder 134 acting on the left large diameter portion pressure receiving surface and the right small diameter portion pressure receiving surface of the pressure boosting piston 139 of the pressure booster 138 is high, but it acts on the right stepped pressure receiving surface. Since the hydraulic pressure in the hydraulic chamber of the hydraulic booster 133 is low,
The boost piston 139 moves to the right, and the on-off valve 140 closes. Therefore, the master cylinder 134 and the wheel cylinder 135 are cut off. After the on-off valve 140 is closed, the brake fluid pressure in the master cylinder 134 is increased by the pressure increaser 138 by the pressure increase ratio {(large diameter portion pressure receiving area) / (small diameter portion pressure receiving area)}, and this pressure increased brake is applied. Hydraulic pressure is supplied to the wheel cylinder 135. As a result, when the pressure source fails, a relatively large brake fluid pressure can be generated with a relatively small pedal effort.

Japanese Patent Laid-Open No. 4-56669 discloses an example of a brake booster system using a negative pressure booster among brake booster systems capable of obtaining a large brake force even when a pressure source fails. Some have been disclosed.

The brake booster system disclosed in this publication also uses a booster having substantially the same structure as the booster 138 shown in FIG. Therefore, FIG.
A brake booster system using the negative pressure booster of this publication will be described with reference to a pressure booster 138 shown in FIG.

The pressure booster 138 of this brake booster system
In the above, the brake fluid pressure of the master cylinder 134 acts on the left large diameter portion pressure receiving surface of the pressure boosting piston 139, and the brake fluid pressure of the wheel cylinder 135 acts on the right small diameter portion pressure receiving surface. Further, on the pressure receiving surface on the right side of the pressure increasing piston 139, the brake fluid pressure of the wheel cylinder 135 acts by the switching valve when the negative pressure source is normal, and communicates with the reservoir when the negative pressure source fails. There is.

Therefore, when the negative pressure source is normal, the pressure increasing piston 139 does not move due to the balance of hydraulic pressure, and the open / close valve 140 is held in the open state. Therefore, the brake fluid pressure of the master cylinder 134 is supplied to the wheel cylinder 135 as it is without being boosted by the booster 138.

When the negative pressure source fails, the switching valve is switched accordingly, so that the pressure receiving surface on the right side step portion of the pressure boosting piston 139 is communicated with the reservoir and no pressure acts. Therefore, the pressure increasing piston 139 moves to the right because the hydraulic pressure is out of balance, the on-off valve 140 closes, and the master cylinder 13
4 and the wheel cylinder 135 are disconnected. On-off valve 1
After 40 is closed, the pressure booster 138 performs the pressure boosting operation as described above.

[0013]

By the way, the hydraulic booster 133 disclosed in Japanese Patent Publication No. 6-29011.
Is a closed center type hydraulic booster that closes when the control valve is inactive and opens when it operates.As a hydraulic booster, the control valve is open when it is inactive and the opening amount is There are open center hydraulic boosters that shrink or close. As an example of the brake booster system 141 having the open center type hydraulic booster, there is a brake booster system as shown in FIGS. 12 and 13. In the figure, 142 is an open center type hydraulic booster, 143 is an input shaft, 144 is a power piston, and 14 is a power piston.
5 is a hydraulic fluid chamber, 146 is a control valve, 147 is a spring chamber, 148 is an output shaft and 149 is a flow switch, 1
50 is an emergency pump. Further, the same components as those in FIG. 11 are designated by the same reference numerals.

When the brake is not operated, the hydraulic fluid discharged from the pump 136 freely flows into the reservoir through the hydraulic fluid chamber 145, the gap between the control valve 146, the spring chamber 147 and the flow switch 149, and the hydraulic fluid chamber The pressure at 145 does not rise and is almost zero.

When the brake is applied, the input shaft 143 moves forward due to the depression of the brake pedal 132, and the gap between the control valves 146 becomes smaller. Therefore, the hydraulic fluid flowing through the control valve 146 is throttled, so that the pressure of the hydraulic fluid chamber 145 increases. The power piston 144 moves forward due to the pressure increase of the working hydraulic chamber 145, and outputs the power piston 144 to the master cylinder 134 via the output shaft 148.

When the pump 136 fails and the flow rate of the hydraulic fluid flowing through the flow switch 149 falls below a predetermined value,
This switch 149 is turned on. As a result, the emergency pump 150 operates and the hydraulic fluid is supplied to the hydraulic booster 142, so that the brake can be operated.

However, if the emergency pump 150 also fails, sufficient braking force cannot be obtained as in the brake boosting system shown in FIG.
The pedal effort of the brake pedal 132 has to be made extremely large as compared with the normal case.

Further, since the emergency pump 150 and the flow switch 149 are required, not only the structure becomes complicated, but also the cost becomes high.

Therefore, such a brake booster system 141 is also provided with a pressure booster 138 shown in FIG. 11, which is activated when the pressure of the working hydraulic chamber of the hydraulic booster 133 is smaller than the brake hydraulic pressure of the master cylinder 134. It is possible to provide it. However, in the open center type hydraulic booster 142, since the flow of the hydraulic fluid from the pump 136 is simply throttled when the brake is operated, the pressure in the hydraulic fluid chamber 145 is generally the brake fluid pressure in the master cylinder 134. Smaller than For this reason, even when the pump 136 or the emergency pump 150 is normal, the pressure booster 138 may be activated during brake operation and the brake fluid pressure may be unnecessarily increased. Also, in the closed center type hydraulic booster 133 shown in FIG. 11, the pressure of the working hydraulic chamber may be lower than the brake hydraulic pressure of the master cylinder 134. The pressure booster 138 may be activated when the brake is activated.

On the other hand, the brake booster system disclosed in Japanese Patent Laid-Open No. 4-56669 has a pressure boosting piston 13
A switching valve for switching the brake fluid pressure of the master cylinder 134 or not to be applied to the pressure receiving surface of the right side step portion of 9 is used, but in general, the switching valve is relatively complicated in structure and There is a problem of high cost. Since the high brake fluid pressure of the master cylinder 134 is applied to the pressure receiving surface on the right side step portion of the normal-time booster piston 139 of the negative pressure source, the sealing performance of the switching valve must be ensured and the sealing structure becomes troublesome. There's a problem. Especially when a switching valve is used, the sealing of the switching valve becomes even more troublesome. Further, since it is necessary to supply the brake fluid from the master cylinder 134 to the annular chamber facing the right side pressure receiving surface of the pressure boosting piston 139, the brake capacity increases correspondingly, and the loss stroke of the brake pedal increases. , Operation delay may occur.

The present invention has been made in view of such circumstances, and an object thereof is to increase the brake fluid pressure of the master cylinder when the pressure source fails, and when the pressure source is normal. An object of the present invention is to provide an inexpensive brake booster system having a simple structure capable of preventing the brake fluid pressure of the master cylinder from unnecessarily increasing.

[0022]

In order to solve the above-mentioned problems, a first aspect of the invention is to provide a pressure source for generating an operating pressure for operating a brake with a working fluid, and a brake operating means for performing a brake operation. And a fluid pressure booster that outputs when the working pressure is generated in the working pressure chamber by the operation of the brake operating means, and a master cylinder that operates by the output of the fluid pressure booster to generate a brake fluid pressure. And a brake cylinder that generates a braking force by supplying brake fluid pressure from the master cylinder, the brake booster system further comprising a passage between the master cylinder and the brake cylinder. , When the brake fluid pressure of the master cylinder becomes larger than a predetermined value, it operates to increase the brake fluid pressure, And a brake fluid pressure increasing means for supplying the brake fluid pressure increasing means to the brake pressure increasing means for preventing the operation of the brake fluid pressure increasing means by operating with the operating pressure of the fluid pressure booster when the pressure source is normal. An operation control means for permitting the operation of the brake fluid pressure increasing means in the event of a fall, and the brake fluid pressure increasing means further comprises a housing for brake fluid pressure increasing means having a stepped hole, and the step. A master cylinder connection chamber slidably fitted in the mounting hole and connected to the master cylinder in the stepped hole, a brake cylinder connection chamber connected to the brake cylinder, and an operation connected to the operation control means. A stepped piston that is formed in each of the control chamber and a passage that is formed in the stepped piston and that communicates between the master cylinder connection chamber and the brake cylinder connection chamber, and this passage A brake fluid pressure increasing means cutoff valve that is provided when the stepped piston is not in operation and communicates with the passage while shutting off the passage when the stepped piston is in operation. The operation control chamber of the brake fluid pressure increasing means is opened by communicating with either a reservoir that stores the working fluid of the pressure source or the reservoir of the master cylinder when the pressure source fails and the pressure is increased. And a shut-off valve for operation control means for shutting off and sealing from these reservoirs when the source is normal.

According to a second aspect of the present invention, the fluid pressure booster is a hydraulic booster, and the operation control means is formed in an operation control means housing and the operation control means housing. A first connection port connected to the control room,
A second connection port formed in the operation control means housing and connected to the reservoir; and a passage of the operation control means that is provided in the operation control means housing and connects the first and second connection ports. The operation control means cutoff valve provided in the passage of the operation control means for opening and closing the passage of the operation control means, and the working hydraulic pressure of the hydraulic booster during brake operation in a normal state of the pressure source. A valve closing piston that receives and operates to close the shutoff valve for operation control means, and a valve opening piston that opens the shutoff valve for operation control means when the brake is actuated when the pressure source fails. Is characterized by.

According to a third aspect of the present invention, the fluid pressure booster is a negative pressure booster, the pressure source is a negative pressure source, and the operation control means includes an operation control means housing. A first connection opening formed in the operation control means housing and connected to the operation control chamber; a second connection opening formed in the operation control means housing and connected to the reservoir; and the operation control means housing A passage for the operation control means, which is drilled and connects the first and second connection ports, and a cutoff valve for the operation control means, which is provided in the passage of the operation control means for opening and closing the passage of the operation control means; A valve closing diaphragm piston for closing the shutoff valve for the operation control means by operating by receiving the negative pressure of the negative pressure source when the negative pressure source is normal, and a shutoff valve for the operation control means when the negative pressure source fails. It is characterized in that it comprises a valve opening piston to open.

Further, according to a fourth aspect of the present invention, the operation control means housing is provided with a chamber facing one end of the valve opening piston and communicating with the master cylinder, and the valve opening piston receives pressure at one end thereof. The shutoff valve for the operation control means is set to open when the brake is operated in the pressure source failure state by the brake fluid pressure of the master cylinder.

Further, the invention according to claim 5 is provided with a spring for urging the valve opening piston in the direction in which the shutoff valve is opened, and the valve opening piston is in the pressure source failure state due to the spring force of the spring. It is set so that the shutoff valve for the operation control means is opened when the brake is actuated.

According to a sixth aspect of the present invention, the fluid pressure booster is a hydraulic booster, and the operation control means is formed on the operation control means housing and the operation control means housing. A first connection port connected to the control room,
A second connection port formed in the operation control means housing and connected to the reservoir; and a passage of the operation control means that is provided in the operation control means housing and connects the first and second connection ports. The operation control means cut-off valve provided in the passage of the operation control means for opening and closing the passage of the operation control means, and opening the operation control means cut-off valve by the spring force of a spring when the pressure source fails. A valve opening piston for releasing the operation control means cutoff valve from the spring force of the spring so that the operation control means cutoff valve is closed by operating by receiving the operating pressure of the pressure source when the pressure source is normal. It is characterized by having.

According to a seventh aspect of the present invention, the fluid pressure booster is a negative pressure booster, the pressure source is a negative pressure source, and the operation control means includes an operation control means housing. A first connection opening formed in the operation control means housing and connected to the operation control chamber; a second connection opening formed in the operation control means housing and connected to the reservoir; and the operation control means housing A passage for the operation control means, which is drilled and connects the first and second connection ports, and a cutoff valve for the operation control means, which is provided in the passage of the operation control means for opening and closing the passage of the operation control means; When the negative pressure source fails, the shutoff valve for the operation control means is opened by the spring force of the spring, and when the negative pressure source is normal, the shutoff valve for the operation control means is operated by receiving the negative pressure of the negative pressure source. Is characterized in that said operation control means for the shut-off valve to close and a valve opening diaphragm piston to release the spring force of the spring.

Further, according to the invention of claim 8, another passage is provided for communicating the operation control chamber with the reservoir, and the flow of the working fluid from the reservoir toward the operation control chamber is provided in the other passage. It is characterized in that a check valve that allows only this is provided.

[0030]

In the brake booster system according to the present invention constructed as described above, when the pressure source is normal, the operation control means operates by the operating pressure of the pressure source to close the shutoff valve for the operation control means. As a result, the operation control chamber of the brake fluid pressure increasing means is shut off from the reservoir and sealed. Therefore, the stepped piston of the brake fluid pressure increasing means becomes inoperable, and the pressure increasing action of the brake fluid pressure increasing means is blocked. Therefore, when the brake is operated in the normal state of the pressure source, the pressure increasing action of the brake fluid pressure increasing means is not unnecessarily performed.

Further, when the pressure source fails, the operating pressure of the pressure source is not introduced into the operation control means, so that the shut-off valve for the operation control means opens. As a result, the operation control chamber of the brake fluid pressure increasing means is communicated with the reservoir and opened. Therefore, the stepped piston of the brake fluid pressure increasing means can be operated, and the pressure increasing action of the brake fluid pressure increasing means can be performed.
Therefore, when the brake is operated when the pressure source is in a failed state, the pressure increasing action of the brake fluid pressure increasing means is surely performed, and the brake fluid pressure of the master cylinder is increased. This ensures that the braking force required when the pressure source fails is obtained.

Further, by simply opening and closing the shutoff valve for the operation control means, the operation control chamber of the brake fluid pressure increasing means and the reservoir are communicated with each other only when the pressure source fails, and shut off otherwise. Therefore, the structure of the shutoff valve for the operation control means is simpler than that of the conventional switching valve. Further, since the brake fluid pressure from the master cylinder is not supplied to the operation control chamber, the seal structure is simplified and the brake capacity is not increased, so that no loss stroke occurs.

Further, since the structure of the emergency pump and the like is complicated and the costly parts are not required, the structure of the brake booster system is simplified and the cost is reduced.

[0034]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram schematically showing a first embodiment of a brake booster system according to the present invention.

As shown in FIG. 1, the brake booster system 1 according to the first embodiment has a brake pedal 2 and an open center type fluid which is controlled by the brake pedal 2 to boost and output the pedal effort. A pressure booster 3, a pump 4 for supplying hydraulic fluid to the hydraulic booster 3, a tandem master cylinder 5 of a two-brake system operated by the hydraulic booster 3, and a master cylinder 5 Brake cylinder 6 to which brake fluid is supplied, and master cylinder 5
And a brake fluid pressure increasing valve 8 arranged in a passage 7 of one brake system between the brake cylinder 6 and the hydraulic pressure booster 3 via a passage 9 and a brake fluid pressure increasing valve. Operation control valve 1 for controlling the operation of 8
0.

As shown in FIG. 2, the hydraulic booster 3 includes an input shaft 11 connected to a brake pedal 2 and a housing 1.
2. A power piston 15 which is fluid-tightly and slidably fitted in a hole in 2 and which is partitioned into an operating hydraulic chamber 13 and a spring chamber 14, and a valve body slidably fitted and inserted in an input shaft 11. 16
A valve seat 17 on which a valve body 16 formed on the power piston 15 can be seated; a control valve 18 including the valve body 16 and the valve seat 17; and an output of the power piston 15 that is integrally provided on the power piston 15 An output shaft 19 which transmits to the piston of the cylinder 5, a return spring 20 which is disposed in the spring chamber 20 and always urges the power piston 15 in the non-operating direction of the brake, and communicates with the working hydraulic chamber 13 and is connected to the pump 4. The pump connection port 21, the operation control valve connection port 22 that is connected to the operation control valve 10 and communicates with the hydraulic fluid chamber 13, and the spring chamber 1
4 and a passage 25 communicating with the reservoir 23, and a passage 25 communicating with the hydraulic fluid chamber 13 formed in the power piston 15 and the valve gap a between the valve body 16 and the valve seat 17. A passage 26 formed in the power piston 15 for communicating the valve gap a with the spring chamber 14 is slidably inserted into the input shaft 11 so as to face the valve body 16 and is always inserted in the direction of the valve body 16 by a spring 27. The spring retainer 28 is urged, and the spring 29 that urges the valve element 16 in a direction to always separate from the valve seat 17 and has a smaller spring force than the spring 27 is provided. In addition, 30 is a stopper that restricts the axial movement of the spring retainer 28 formed on the input shaft 11, 31 is only provided in the pump connection port 21 and allows only the flow of the hydraulic fluid from the pump 4 toward the hydraulic fluid chamber 13. It is a check valve. The hydraulic booster 3 is in a state in which the gap a between the valve body 16 and the valve seat 17 shown in the drawing is maximized when the hydraulic booster 3 is not operating.

As shown in FIG. 3, the brake fluid pressure increasing valve 8 is slidably fitted in the stepped hole of the housing 32.
Master cylinder connection chamber 3 connected to master cylinder 5
3 and a brake cylinder connection chamber 34 connected to the brake cylinder 6 and a stepped piston 36 partitioned and formed into an annular operation control valve connection chamber 35 connected to the operation control valve 10 via a passage 42. The master cylinder connection chamber 33 and the brake cylinder connection chamber 3 are provided in the hole 36.
4, a passage 37 communicating with the valve 4, a valve body 38 arranged in the passage 37, and a valve seat 39 fixedly mounted on the stepped piston 36.
It is normally opened to allow the flow of brake fluid in both directions between the chambers 33 and 34, and when the stepped piston 36 moves, the valve body 38 is seated on the valve seat 39 to close the chamber 33 and the chamber. A shutoff valve 40 that shuts off communication with the valve 34 and a spring 41 that constantly biases the stepped piston 36 in the non-operating direction (rightward in FIG. 3). Further, the chamber 35 is connected to the reservoir 23 via a passage 43, and the passage 43 is provided with a check valve 44 that blocks the flow of the hydraulic fluid from the chamber 35 to the reservoir 23. The cup seal provided on the stepped piston 36 blocks the flow of the brake fluid from the chamber 33 to the chamber 35 and from the chamber 34 to the chamber 35. When the brake fluid pressure increasing valve 8 is not in operation, the stepped piston 36 is located on the rightmost side as shown in the drawing, and the valve body 38 is
Is in contact with the stopper 45 and the shutoff valve 40 is opened. The brake fluid pressure increasing valve 8 constitutes the brake fluid pressure increasing means of the present invention.

Similarly, as shown in FIG. 3, the operation control valve 1
0 is the passage 42, that is, the first connection port 47 of the housing 46 connected to the chamber 35 of the operation control valve 10, and the passage 4
3, that is, the second connection port 48 of the housing 46 connected to the reservoir 23, the passage 49 in the housing 46 that communicates the first and second connection ports 47, 48, and the passage 49.
And a shutoff valve 52 which is provided in the housing and includes a valve body 50 and a valve seat 51 on which the valve body 50 can be seated. Hydraulic pressure chamber 1 of hydraulic booster 3
A valve closing piston 54 for receiving the hydraulic fluid pressure of No. 3 and urging the valve body 50 in a direction to seat it on the valve seat 51;
5 and a valve opening piston 56 that constantly urges the master cylinder 5 and urges the valve body 50 in a direction to separate it from the valve seat 51. In addition, 57 faces one end of the valve opening piston 56, and
The spring 55 is housed and the master cylinder 3
This is the chamber where the brake fluid pressure is introduced.

In the operation control valve 10, when the brake shown in FIG. 3 is not operated, the valve body 50 is seated on the valve seat 51 by the urging force of the valve closing piston 54 by the spring force of the first spring 53, and the shutoff valve 52 is operated. Has been closed. In that case, the valve body 50 is urged by the urging force of the valve opening piston 56 by the spring force of the second spring 55, but the spring force of the first spring 53 is the second spring 55. Is set to be larger than the spring force of the valve seat 50. Therefore, at this time, the valve body 50 does not separate from the valve seat 51.

When the pump 4 is operating in the normal state, the hydraulic fluid pressure of the hydraulic booster 3 acts on the valve closing piston 54 and the brake fluid pressure of the master cylinder 5 acts on the valve opening piston 56. The valve element 50 is also urged by these hydraulic pressures. In that case, the urging force of the valve closing piston 54 due to the spring force of the first spring 53 and the hydraulic fluid pressure becomes larger than the urging force of the valve opening piston 56 due to the spring force of the second spring 55 and the brake fluid pressure. The effective pressure receiving areas of both pistons 54, 55 are set in consideration of the spring force of the first and second springs 53, 55.
Therefore, at this time, the valve body 50 does not separate from the valve seat 51.

Further, when the brake is actuated when the pump 4 is in failure, the hydraulic fluid pressure of the hydraulic booster 3 does not act on the valve closing piston 54, whereas the master cylinder 5 acts on the valve opening piston 56. Brake fluid pressure acts, and at this time the valve body 50 is urged by the spring force of the first and second springs 53 and 55 and the brake fluid pressure of the master cylinder 5. In that case, the urging force of the valve opening piston 56 due to the spring force of the second spring 55 and the brake fluid pressure is the first spring 53.
The effective pressure receiving area of the valve opening piston 55 is set in consideration of the spring force of the first and second springs 53, 55 so that it is larger than the urging force of the valve closing piston 54 due to the spring force. Therefore, at this time, the valve body 50
Is separated from the valve seat 51 by the urging force of the valve opening piston 55.

In this way, the operation control valve 10
Is a shutoff valve 52 when the brake is operated in a normal state of the pump 4.
Is closed, and the chamber 35 of the brake fluid pressure increasing valve 8 is shut off from the reservoir 23 so as to be hermetically sealed. In the closed state of the chamber 35, the stepped piston 36 becomes inoperable and the brake fluid pressure increasing valve 8 is prevented from increasing its pressure. Further, the operation control valve 10 opens the shut-off valve 52 when the brake is operated in the failure state of the pump 4, and communicates the chamber 35 of the brake fluid pressure increasing valve 8 with the reservoir 23 to open the chamber. When the chamber 35 is opened, the stepped piston 36 becomes operable, and the brake fluid pressure increasing valve 8 is allowed to increase its pressure. The operation control valve 10 constitutes the operation control means of the present invention, and the chamber 35 constitutes the operation control chamber of the present invention. Although not shown, the other brake system is similarly provided with a brake fluid pressure increasing valve 8 and an operation control valve 10.

Next, the operation of the first embodiment thus constructed will be described. When the brake is not operated as shown in FIGS. 1 to 3, the valve clearance a of the control valve 18 of the hydraulic booster 3 is shown.
Is the largest. Therefore, in the normal state of the pump 4, the hydraulic fluid discharged from the pump 4 is
1, hydraulic fluid chamber 13, passage 25, valve gap a, passage 26,
It flows into the reservoir 23 via the spring chamber 14 and the reservoir connection port 24. That is, by driving the pump 4,
The hydraulic fluid in the reservoir 23 is circulated through the hydraulic booster 3 and returns to the reservoir 23 again. Further, since the shutoff valve 52 of the operation control valve 10 is closed, the working fluid in the chamber 35 of the brake fluid pressure increasing valve 8 is in a sealed state.

In this state, when the brake pedal 2 is depressed to perform the brake operation, the input shaft 11 moves forward, the valve body 16 approaches the valve seat 17, and the valve clearance a becomes smaller according to the pedal effort. Therefore, the valve gap a becomes smaller, and the hydraulic fluid flowing through the valve gap a is throttled. As a result, the hydraulic fluid pressure in the hydraulic fluid chamber 13 rises, and the power piston 15 moves forward. With the advance of the power piston 15, the output shaft 19 advances and advances the piston of the master cylinder 5. The master cylinder 5 generates a brake fluid pressure, and this brake fluid pressure is supplied to the brake cylinder 6 through the passage 7, the passage 37 of the brake fluid pressure increasing valve 8 and the open shutoff valve 40 to operate the brake. .

At this time, the hydraulic fluid pressure in the hydraulic fluid chamber 13 passes through the passage 9 and the valve closing piston 54 of the operation control valve 10
Therefore, the valve closing piston 54 biases the valve body 50 in the direction in which the seating force on the valve seat 51 increases. Further, since the brake fluid pressure of the master cylinder 5 acts on the valve opening piston 56 of the operation control valve 10 through the passage 7, the valve opening piston 56 moves the valve body 50 in the direction in which the seating force on the valve seat 51 decreases. Energize. In this state, the valve closing piston 5
Since the urging force from No. 4 is larger than the urging force of the valve opening piston 56, the valve body 50 remains seated on the valve seat 51, and the shutoff valve 52 is maintained in the closed state. Therefore, room 3
The hydraulic fluid in 5 is kept sealed.

On the other hand, when the brake is operated, the brake fluid pressure of the master cylinder 5 in the chamber 33 of the brake fluid pressure increasing valve 8 acts on the stepped piston 36 leftward, and the brake fluid pressure of the master cylinder 5 in the chamber 34 increases. It acts on the stepped piston 36 in the right direction, and the stepped piston 3
Due to the difference in the effective pressure receiving area 6 of FIG. However, since the hydraulic fluid in the chamber 35 is in a sealed state, the stepped piston 36 does not move to the left even when this leftward force is applied. Therefore, in the brake fluid pressure increasing valve 8, the shutoff valve 40 is not closed and the pressure increasing operation is not performed. Therefore, the brake fluid pressure of the master cylinder 5 is supplied to the brake cylinder 6 without being increased. As described above, in this embodiment, even if the hydraulic fluid pressure is lower than the brake fluid pressure by the open center type hydraulic booster 3, the brake fluid pressure boosting valve 8 is unnecessary to increase the pressure when the pump 4 is normal. The action is blocked.

When the hydraulic fluid pressure in the hydraulic fluid chamber 13 rises above a predetermined value in the brake operating state, both the valve element 16 and the spring retainer 28 move to the right against the spring force of the spring 27. Therefore, the valve gap a of the control valve 18 becomes large, the throttle of the hydraulic fluid flowing through the valve gap a becomes small, and the hydraulic fluid pressure in the hydraulic fluid chamber 13 falls below a predetermined value. In this way, the valve element 16, the spring retainer 28 and the spring 27 perform a relief action of reducing the hydraulic fluid pressure to a predetermined value or less when the hydraulic fluid pressure rises to a predetermined value or more.

When the brake pedal 2 is released, the input shaft 1
1 and the valve body 16 retract, and the valve gap a of the control valve 18 increases. For this reason, the hydraulic fluid flowing through the valve gap a cannot be throttled, and the hydraulic fluid pressure in the hydraulic fluid chamber 13 drops to zero. As a result, the power piston 15 and the output shaft 19
And the piston of the master cylinder 5 moves backward, the brake fluid pressure in the master cylinder 5 drops to 0, and the brake is released. Then, even if the hydraulic fluid pressure and the brake hydraulic pressure decrease, the shutoff valve 52 of the operation control valve 10 is maintained in the closed state.

When the pump 4 fails, the hydraulic fluid stops flowing to the hydraulic booster 3. Therefore, even if the brake pedal 2 is depressed to reduce the valve clearance a of the control valve 18, the hydraulic fluid pressure in the hydraulic fluid chamber 13 does not rise, and the hydraulic booster 3
Does not output by boosting the pedal effort. When the brake pedal 2 is further depressed, the front end of the input shaft 11 comes into contact with the rear end of the output shaft 19, and thereafter, the output shaft 19 advances only by the pedaling force to operate the piston of the master cylinder 5. Therefore, the master cylinder 5 generates the brake fluid pressure only by the pedaling force, and this brake fluid pressure is supplied to the brake cylinder 6. The brake hydraulic pressure at this time is smaller than the brake hydraulic pressure when the master cylinder 5 is operated by the output of the hydraulic booster 3 when the pump 4 is normal.

By the way, the hydraulic pressure chamber 1 of the hydraulic booster 3
Since the hydraulic fluid pressure in 3 does not rise, the urging force by which the valve closing piston 54 that receives this hydraulic fluid pressure urges the valve body 50 is only due to the spring force of the first spring 53.
On the other hand, the valve opening piston 56 is connected to the master cylinder 5
Since the brake fluid pressure is applied to the valve opening piston 56, the urging force for urging the valve opening piston 56 is due to the brake fluid pressure and the spring force of the second spring 55. Therefore, the valve opening piston 56 moves the valve body 50 together with the valve closing piston 54 to the left against the spring force of the first spring 53 and separates from the valve seat 51, so that the shutoff valve 52 opens. Therefore, the chamber 35 of the brake fluid pressure increasing valve 8 communicates with the reservoir 23 through the passage 42, the first connection port 47, the open shutoff valve 52, the second connection port 48, and the passage 43,
Be released.

When the chamber 35 is opened, the stepped piston 36 advances due to the difference in effective pressure receiving areas at both ends of the stepped piston 36 which receives the brake fluid pressure of the master cylinder 5.
Due to the forward movement of the stepped piston 36, the valve body 38 moves to the valve seat 39.
The shut-off valve 40 is closed by sitting on the valve, and thereafter, the shut-off valve 40 performs a check function of blocking the flow of the brake fluid from the chamber 34 to the chamber 33. While the shutoff valve 40 is closed, the brake fluid pressure from the master cylinder 5 in the chamber 33 is increased due to the difference in effective pressure receiving area between both ends of the stepped piston 36, and the hydraulic pressure is increased in the chamber 3.
Occurs at 4. That is, the brake fluid pressure increasing valve 8 performs a pressure increasing action to increase the brake fluid pressure. Since the increased hydraulic pressure in the chamber 34 is supplied to the brake cylinder 6,
The brake cylinder 6 generates a large braking force. As described above, even if the hydraulic booster 3 does not perform the boosting operation due to the failure of the pump 4, the brake hydraulic pressure increasing valve 8 increases the brake hydraulic pressure, so that the brake operation is performed only by the pedal effort. However, you will be able to obtain a large braking force.

When the brake pedal 2 is released, the input shaft 1
1, the valve body 16 and the output shaft 19 are retracted, and the hydraulic booster 3 is brought into the non-actuated state shown in FIG. Along with this, the piston of the master cylinder 5 also retracts, so the brake fluid pressure in the master cylinder 5 becomes zero. As a result, the stepped piston 36 of the brake fluid pressure increasing valve 8 is also retracted to the non-operating position, the shutoff valve 40 is opened, and the master cylinder 5 and the brake cylinder 6 communicate with each other. Therefore, the brake fluid pressure in the brake cylinder 7 becomes 0, and the brake is released.

Since the brake fluid pressure in the brake cylinder 7 becomes 0, the valve closing piston 54 is moved to the first piston 5
The spring force of 3 moves the valve element 50 together with the valve opening piston 56 to the right against the spring force of the second spring 55 to seat it on the valve seat 51. As a result, the shutoff valve 52 is closed. In addition, the stepped piston 3 of the brake fluid pressure increasing valve 8
6 is moved to the right by the spring force of the spring 41. At this time, since the shutoff valve 52 is closed, the pressure inside the chamber 35 becomes negative, but the hydraulic fluid flows into the chamber 35 from the reservoir 23 through the passage 43 and the check valve 44. Therefore, the negative pressure in the chamber 35 is released, and the stepped piston 36 smoothly returns to the inoperative position shown.

FIG. 4 is a diagram schematically showing a second embodiment of the present invention, and FIG. 5 is a diagram showing a brake fluid pressure increasing valve and an operation control valve used in this second embodiment.
The same components as those in the first embodiment described above are designated by the same reference numerals, and detailed description thereof will be omitted.

In the first embodiment, when the master cylinder 5 and the operation control valve 10 are connected to each other and the valve opening piston 56 of the operation control valve 10 receives the brake fluid pressure of the master cylinder 5, when the pump 4 fails. Although the valve body 50 is separated from the valve seat 51, in the second embodiment, as shown in FIGS.
Is not connected to the operation control valve 10 so that the valve opening piston 56 of the operation control valve 10 does not receive the brake fluid pressure of the master cylinder 5.

That is, as shown in FIG. 5, the chamber 57, in which the second spring 55 for urging the valve opening piston 56 is accommodated, is always in communication with the atmosphere. It is biased only by the spring force. In that case, when the valve closing piston 54 does not receive the increased hydraulic pressure of the hydraulic booster 3 due to the brake operation, the spring force of the second spring 55 is:
The valve opening piston 56 moves the valve body 50 and the valve closing piston 54 to the left against the spring force of the first spring 53 to separate the valve body 50 from the valve seat 51, and the valve closing piston 54 The size is set so that the valve body 50 and the valve opening piston 56 can be moved to the right to seat the valve body 50 on the valve seat 51 while receiving the increased hydraulic fluid pressure.

Therefore, in the second embodiment, unlike the first embodiment, the shut-off valve 52 is open and the first and second connection ports 47 and 48 are in communication when the brake is not operated,
That is, the chamber 35 of the brake fluid pressure increasing valve 8 is in communication with the reservoir 23, and the chamber 35 is open.

During the brake operation of the pump 4 in the normal state, the increased hydraulic fluid pressure of the hydraulic booster 3 acts on the valve closing piston 54, so that the valve closing piston 54 operates with the hydraulic fluid pressure and the first piston 53. The valve element 50 is moved to the right side against the spring force of the second spring 55 together with the valve opening piston 56 by the spring force of, and seated on the valve seat 51. As a result, the shutoff valve 52 is closed. Therefore, the hydraulic fluid in the chamber 35 is sealed, and the stepped piston 36 becomes immovable as in the first embodiment. Therefore, the brake fluid pressure increasing valve 8 does not perform the pressure increasing action.

Since the hydraulic fluid pressure of the hydraulic pressure booster 3 does not rise during brake operation when the pump 4 is in a failed state, the shutoff valve 52 is opened by the valve opening piston 56 in the same manner as described above. The stepped piston 36 is the master cylinder 5
Moves to the left as the brake fluid pressure increases and the shutoff valve 40 of the brake fluid pressure increasing valve 8 closes. This allows
The brake fluid pressure increasing valve 8 performs a pressure increasing action. This second
The other operation of the embodiment is the same as that of the above-mentioned first embodiment, and therefore its explanation is omitted.

In the above-mentioned embodiment, the present invention is applied to the brake booster system including the open center type hydraulic booster 3. However, the present invention includes the closed center type hydraulic booster. It can also be applied to a brake booster system. In this closed center type hydraulic booster,
When the brake is operated in the normal state of the pump 4, the hydraulic fluid pressure is usually higher than the brake hydraulic pressure of the master cylinder 5, and the brake fluid pressure increasing valve 8 hardly operates. Even if the working fluid pressure is lower than the brake fluid pressure of the master cylinder 5 despite being normal, the brake fluid pressure increasing valve 8 is reliably prevented from performing unnecessary pressure increasing action.

FIG. 6 is a view similar to FIG. 1, schematically showing a third embodiment of the present invention, and FIG. 7 shows a brake fluid pressure increasing valve and an operation control valve used in this third embodiment. 4 is a view similar to FIG. The same components as those in the first embodiment described above are designated by the same reference numerals, and detailed description thereof will be omitted.

Although the hydraulic booster 3 is provided in the first embodiment, the brake booster system of the third embodiment uses the negative booster 58 as shown in FIG. . The negative pressure booster 58 is a conventionally known negative pressure booster, and the control valve (not shown) of the negative pressure booster 58 is switched by depressing the brake pedal 2 to introduce the atmosphere and reduce the atmospheric pressure and the negative pressure. A diaphragm power piston (not shown) is actuated by the differential pressure from the negative pressure from the pressure source 59 and outputs from an output shaft (not shown).

Further, in the first embodiment, the operation control valve 10 receives the working hydraulic pressure of the working hydraulic pressure chamber 13 of the hydraulic booster 3 and urges the valve body 50 in the direction to be seated on the valve seat 51. A valve closing piston 54 is provided, which is shown in FIG.
As shown in FIG. 5, a valve closing diaphragm piston 54 'is provided which receives a negative pressure from a negative pressure source 59 and urges the valve body 50 in a direction to seat it on the valve seat 51. The other structure of the operation control valve 10 is exactly the same as that of the first embodiment. Also, the first
In the third embodiment, the passage 43 communicates with the reservoir 23 of the hydraulic booster 3, but in the third embodiment, the passage 43 communicates with the reservoir 5a of the master cylinder 5.

The other structure of the brake booster system of the third embodiment is exactly the same as that of the first embodiment except that the pump 4 and the reservoir 23 of the hydraulic booster 3 of the first embodiment are not used. Is.

In the third embodiment thus constructed, the atmospheric pressure is constantly acting on one surface side (the left surface side in FIG. 7) of the valve closing diaphragm piston 54 'of the operation control valve 10, and the negative pressure is applied. This valve closing diaphragm piston 5 when the brake is not operated in the normal driving state of the source 59.
Since the negative pressure from the negative pressure source 59 acts on the other surface side (the right surface side in FIG. 7) of 4 ', the valve closing diaphragm piston 54' causes the valve body 50 to move to the valve seat 51. While being seated, it is urged in such a direction that its seating force increases.
Therefore, since the shutoff valve 52 of the operation control valve 10 is closed, the working fluid in the chamber 35 of the brake fluid pressure increasing valve 8 is in a sealed state.

In this state, when the brake pedal 2 is depressed to perform the braking operation, the control valve of the negative pressure booster 3 is switched and the atmosphere is introduced into the negative pressure booster 3 and the atmospheric pressure and the negative pressure source 59 are supplied. The diaphragm power piston of the negative pressure booster 3 is actuated by the pressure difference from the negative pressure of, and outputs from the output shaft.
As a result, the piston of the master cylinder 5 operates to generate brake fluid pressure, and this brake fluid pressure is supplied to the brake cylinder 6 in the same manner as in the above-described respective embodiments, and the brake operates.

At this time, the brake fluid pressure of the master cylinder 5 acts on the valve opening piston 56 of the operation control valve 10 through the passage 7, so that the valve opening piston 56 is closed.
Is urged in the direction in which the seating force on the valve seat 51 decreases. However, in this state, since the urging force from the valve closing diaphragm piston 54 'is larger than the urging force of the valve opening piston 56, the valve body 50 remains seated on the valve seat 51 and the shutoff valve 52 is kept closed. It That is, the hydraulic fluid in the chamber 35 is maintained in a sealed state.

Therefore, the stepped piston 36 does not move leftward even if a leftward force due to the pressure receiving area difference is applied, as in the above-described embodiments. Therefore, in the brake fluid pressure increasing valve 8, the shutoff valve 40 is not closed and the pressure increasing operation is not performed. Therefore, the brake fluid pressure of the master cylinder 5 is supplied to the brake cylinder 6 without being increased. As described above, in this embodiment, it is possible to prevent the brake fluid pressure increasing valve 8 from unnecessarily increasing the pressure when the negative pressure source 59 of the negative pressure booster 3 is normal.

When the negative pressure source 59 fails, the negative pressure cannot be supplied to the negative pressure booster 3. Therefore, even if the control valve of the negative pressure booster 3 is switched by depressing the brake pedal 2, the negative pressure booster 3 does not operate and boosts the pedal effort and does not output it. When the brake pedal 2 is further depressed, the negative pressure booster 3 advances its output shaft only by the pedal effort,
The piston of the master cylinder 5 is operated. Therefore,
The master cylinder 5 generates a brake fluid pressure only by the pedal effort, and this brake fluid pressure is supplied to the brake cylinder 6.

By the way, since the negative pressure stops acting on the valve closing diaphragm piston 54 'due to the failure of the negative pressure source,
Similar to the first embodiment described above, the valve opening piston 56 has the valve body 5
0 together with the valve closing diaphragm piston 54 'moves to the left against the spring force of the first spring 53, and the shutoff valve 5
Open 2. Therefore, the chamber 35 of the brake fluid pressure increasing valve 8 communicates with the reservoir 5a and is opened.

By opening the chamber 35, the brake fluid pressure increasing valve 8 performs a pressure increasing action to increase the brake fluid pressure as in the first embodiment, and the brake cylinder 6 generates a large braking force. The other operation of the third embodiment is the same as the operation of the first embodiment.

According to the third embodiment, by simply opening and closing the shutoff valve 52, a negative pressure source is provided between the operation control valve connection chamber 35 of the brake fluid pressure increasing valve 8 and the reservoir 5a of the master cylinder 5. The structure of the shutoff valve 52 is simpler than that of the switching valve disclosed in the above-mentioned publication because the valve 59 is communicated only when it fails and is shut off otherwise. Further, since the brake fluid pressure from the master cylinder 5 is not supplied to the operation control valve connection chamber 35, the seal structure is simplified and the brake capacity is not increased, so that no loss stroke occurs.

Incidentally, in the third embodiment, the first spring 53 is replaced by the valve closing diaphragm piston 5 in FIG.
4'is arranged on the side communicating with the atmosphere so that its spring force urges in the right direction, that is, in the direction in which the valve body 50 is seated on the valve seat 51. The first spring 53 in FIG. The valve closing diaphragm piston 54 'may be arranged on the side communicating with the negative pressure source 59 so that its spring force is biased to the left. In this case, when the negative pressure source 59 fails, the valve body 50 can be separated from the valve seat 51 more quickly, and the responsiveness is improved.

FIG. 8 is a view similar to FIG. 4, schematically showing a fourth embodiment of the present invention, and FIG. 9 shows a brake fluid pressure increasing valve and an operation control valve used in this fourth embodiment. 6 is a view similar to FIG. The same components as those in the first to third embodiments described above are designated by the same reference numerals, and detailed description thereof will be omitted.

In the second embodiment, the hydraulic booster 3 is provided, but in the brake booster system of the fourth embodiment, as shown in FIG. A pressure booster 58 is used.

Further, in the second embodiment, the operation control valve 10 receives the working hydraulic pressure of the working hydraulic pressure chamber 13 of the hydraulic booster 3 and urges the valve body 50 in the direction to be seated on the valve seat 51. A valve closing piston 54 is provided, which is shown in FIG.
As shown in FIG. 5, a valve closing diaphragm piston 54 'is provided which receives a negative pressure from a negative pressure source 59 and urges the valve body 50 in a direction to seat it on the valve seat 51. The other structure of the operation control valve 10 is exactly the same as that of the second embodiment. Also, the second
In the embodiment, the passage 43 communicates with the reservoir 23 of the hydraulic booster 3, but in the fourth embodiment, the passage 43 communicates with the reservoir 5a of the master cylinder 5.

The other structure of the brake booster system of the fourth embodiment is exactly the same as that of the second embodiment except that the pump 4 and the reservoir 23 of the hydraulic booster 3 of the second embodiment are not used. Is.

In the fourth embodiment thus constructed, the atmospheric pressure is constantly acting on one surface side of the valve closing diaphragm piston 54 'of the operation control valve 10, and
When the negative pressure source 59 is normally driven and the brake is not operated, the negative pressure source 59 is provided on the other surface side of the valve closing diaphragm piston 54 '.
Since a negative pressure is applied to the valve closing diaphragm piston 54 ′, the valve closing diaphragm piston 54 ′ urges the valve body 50 against the spring force of the second spring 55 to seat it on the valve seat 51. Therefore, since the shutoff valve 52 of the operation control valve 10 is closed, the working fluid in the chamber 35 of the brake fluid pressure increasing valve 8 is in a sealed state.

When the brake is actuated by depressing the brake pedal 2 in this state, the operation is the same as that of the third embodiment described above, and normal braking is performed by the brake fluid pressure boosted by the negative pressure booster 3. At the same time, the brake fluid pressure increasing valve 8 does not increase the pressure.

When the negative pressure source 59 fails, the negative pressure booster 3 does not perform a boosting operation as in the third embodiment, and the master cylinder 5 generates a brake fluid pressure only by the pedal effort. Further, due to the failure of the negative pressure source 59, the negative pressure does not act on the valve closing diaphragm piston 54 ', and the above-mentioned second pressure
As in the embodiment, the valve opening piston 56 moves the valve body 50 to the left side against the spring force of the first spring 53 together with the valve closing diaphragm piston 54 'by the spring force of the second spring 55, so that the shutoff valve is operated. 52 opens. Therefore, as in the second embodiment, the brake fluid pressure increasing valve 8 performs a pressure increasing action to increase the brake fluid pressure, and the brake cylinder 6 generates a large braking force. The other operation of the fourth embodiment is the same as the operation of the second embodiment. The effects of the fourth embodiment are also the same as those of the second and third embodiments.

FIG. 10 is a view similar to FIG. 9, showing a fifth embodiment of the present invention. The same components as those in the above-described embodiments are designated by the same reference numerals, and detailed description thereof will be omitted.

In the above-described fourth embodiment, the opening / closing of the shutoff valve 52 is controlled by the valve closing diaphragm piston 54 'and the valve opening piston 56 which is operated only by the spring force of the second spring 55. In the embodiment, as shown in FIG. 10, the valve closing diaphragm piston 54 'is omitted, and instead of the valve opening piston 56, the valve opening diaphragm operated by the negative pressure of the negative pressure source 59 and the spring force of the second spring 55. The piston 60 is used.

That is, the valve body 50 of the shutoff valve 52 is simply urged by the valve spring 61 in the direction to be seated on the valve seat 51. In addition, the valve opening diaphragm piston 60
The valve element 50 to the valve seat 5 by the spring force of the second spring 55.
The valve body 50 is urged by the spring force of the second spring 55 due to the differential pressure from the atmospheric pressure when the negative pressure from the negative pressure source 59 is received. It is designed to be released from.

The other structure of the operation control valve 10 of the fifth embodiment is exactly the same as that of the fourth embodiment. The other structure of the brake booster system of the fifth embodiment is exactly the same as that of the fourth embodiment.

In the fifth embodiment thus constructed, the atmospheric pressure is constantly acting on one surface (the left surface in FIG. 10) of the valve opening diaphragm piston 60 of the operation control valve 10, and the negative pressure source 59 is provided. When the brake is not operated during normal driving of the valve opening diaphragm, the negative pressure from the negative pressure source 59 acts on the other surface (the right surface in FIG. 10) of the valve opening diaphragm piston 60, so that the differential pressure is generated. The piston 60 releases the valve body 50 from the spring force of the second spring 55. Therefore, the valve body 50 has the valve seat 51.
Since the shutoff valve 52 is seated on the valve, the hydraulic fluid in the chamber 35 of the brake fluid pressure increasing valve 8 is in a sealed state.

When the brake is operated by depressing the brake pedal 2 in this state, the operation is the same as that of the fourth embodiment described above, and normal braking is performed by the brake fluid pressure boosted by the negative pressure booster 3. At the same time, the brake fluid pressure increasing valve 8 does not increase the pressure.

When the negative pressure source 59 fails, the negative pressure booster 3 does not perform a boosting action as in the fourth embodiment, and the master cylinder 5 generates brake fluid pressure only by the pedal effort. Further, the negative pressure does not act on the valve opening diaphragm piston 60 due to the failure of the negative pressure source 59, and the valve opening diaphragm piston 60 causes the valve body 50 to move the valve body 50 by the spring force of the second spring 55 as in the fourth embodiment. Since it moves to the left against the spring force of the valve spring 61, the shutoff valve 52 opens. Therefore, as in the fourth embodiment, the brake fluid pressure increasing valve 8 performs a pressure increasing action to increase the brake fluid pressure, and the brake cylinder 6 generates a large braking force. The other operation of the fifth embodiment is the same as that of the fourth embodiment. The effect of the fifth embodiment is also the same as that of the fourth embodiment.

In the fifth embodiment, the negative pressure booster 58 is used, but as an example corresponding to the fifth embodiment using the hydraulic booster 3, the operation control valve 1 shown in FIG.
0 valve closing piston 54 is omitted, and valve opening piston 56
By applying hydraulic fluid pressure from the hydraulic fluid pressure chamber 13 of the hydraulic pressure booster 3 to the surface opposite to the second spring 55, the valve body 50 is released from the urging force of the spring force of the second spring 55. You can also choose to do so. However, in this case, in the chamber on the opposite side of the second spring 55 of the valve opening piston 56 in FIG. 10, the chamber that houses the second spring 55 communicates with the reservoir 5a, so this chamber and the reservoir 5a It goes without saying that a sealing member for blocking the above is required.

[0089]

As is apparent from the above description, according to the brake booster system of the present invention, when the pressure source is normal, the operation control means prevents the pressure increasing action of the brake fluid pressure increasing means. Therefore, it is possible to surely prevent the pressure increasing action of the brake fluid pressure increasing means from being unnecessarily performed when the brake is operated in the normal state of the pressure source.

Moreover, when the pressure source fails, the operation control means allows the brake fluid pressure increasing means to increase the pressure, so that the brake fluid pressure is increased when the brake is operated in the pressure source failure state. The brake fluid pressure of the master cylinder can be increased by the pressure increasing action of the means, and the required braking force can be reliably obtained with a relatively light operating force.

Further, since the pressure increasing action of the brake fluid pressure increasing means is controlled by simply opening and closing the shutoff valve for the operation control means, the structure of the shutoff valve for the operation control means is changed to the conventional switching valve. Compared to this, it can be done easily and the cost can be reduced.

Further, since the brake fluid pressure from the master cylinder is not supplied to the operation control chamber of the brake fluid pressure increasing means, the seal structure is simplified and the brake capacity is not increased. It also eliminates the possibility of

Furthermore, the parts such as the emergency pump having a complicated structure and high cost are not required, the structure of the brake boosting system is further simplified, and the cost can be further reduced.

[Brief description of the drawings]

FIG. 1 is a first brake boosting system according to the present invention.
It is a figure which shows an Example typically.

FIG. 2 is a sectional view showing an open center type hydraulic booster used in the first and second embodiments.

FIG. 3 is a cross-sectional view showing a brake fluid pressure increasing valve and an operation control valve used in the first embodiment.

FIG. 4 is a second brake boosting system according to the present invention.
It is a figure which shows an Example typically.

FIG. 5 is a cross-sectional view showing a brake fluid pressure increasing valve and an operation control valve used in a second embodiment.

FIG. 6 is a third brake boosting system according to the present invention.
It is a figure which shows an Example typically.

FIG. 7 is a cross-sectional view showing a brake fluid pressure increasing valve and an operation control valve used in a third embodiment.

FIG. 8 is a fourth part of the brake boosting system according to the present invention.
It is a figure which shows an Example typically.

FIG. 9 is a cross-sectional view showing an example of a brake fluid pressure increasing valve and an operation control valve used in a fourth embodiment.

FIG. 10 is a cross-sectional view showing another example of the brake fluid pressure increasing valve and the operation control valve used in the fourth embodiment.

FIG. 11 is a diagram showing an example of a conventional brake booster system.

FIG. 12 is a diagram showing an example of a brake booster system including a conventional open center type hydraulic booster.

FIG. 13 is a sectional view showing an example of a conventional open center type hydraulic booster.

[Explanation of symbols]

1 ... Brake boost system, 2 ... Brake pedal, 3 ...
Open center type hydraulic booster, 4 ... Pump, 5 ... Tandem master cylinder, 6 ... Brake cylinder, 7, 9 ...
Passage, 8 ... Brake fluid pressure increasing valve, 10 ... Operation control valve, 11 ... Input shaft, 13 ... Operating fluid pressure chamber, 15 ... Power piston, 16 ... Valve body, 17 ... Valve seat, 18 ... Control valve, 1
9 ... Output shaft, 23 ... Reservoir, 32 ... Housing, 33
... master cylinder connection chamber, 34 ... brake cylinder connection chamber, 35 ... operation control valve connection chamber, 36 ... stepped piston, 37 ... passage, 38 ... valve body, 39 ... valve seat, 40 ... shut-off valve, 42, 43 ... Passage, 44 ... Check valve, 46 ...
Housing, 47 ... First connection port, 48 ... Second connection port, 4
9 ... passage, 50 ... valve body, 51 ... valve seat, 52 ... shutoff valve, 5
3 ... 1st spring, 54 ... Valve closing piston, 54 '...
Valve closing diaphragm piston, 55 ... second spring,
56 ... Valve opening piston, 57 ... Chamber, 58 ... Negative pressure booster, 59 ... Negative pressure source, 60 ... Valve opening diaphragm piston

Claims (8)

[Claims] 1. A pressure source for generating an operating pressure for operating a brake by a working fluid, a brake operating means for performing a brake operation, and the operating pressure generated in an operating pressure chamber by operating the brake operating means. Generated by the fluid pressure booster, the master cylinder that operates by the output of this fluid pressure booster to generate brake fluid pressure, and the brake fluid pressure is supplied from this master cylinder to generate the braking force. A brake booster system including a brake cylinder for operating the brake cylinder, wherein the brake cylinder is provided in a passage between the master cylinder and the brake cylinder, and operates when the brake fluid pressure of the master cylinder exceeds a predetermined value. Brake fluid pressure increasing means for increasing the brake fluid pressure and supplying it to the brake cylinder, and when the pressure source is normal. And an operation control unit that operates by the operating pressure of the fluid pressure booster to prevent the operation of the brake fluid pressure increasing unit and allows the operation of the brake fluid pressure increasing unit when the pressure source fails. Further, the brake fluid pressure increasing means is slidably fitted in a housing for brake fluid pressure increasing means having a stepped hole and slidably fitted in the stepped hole. A stepped piston, which is partitioned into a master cylinder connection chamber connected to the master cylinder, a brake cylinder connection chamber connected to the brake cylinder, and an operation control chamber connected to the operation control means, and the stepped piston. A passage that is drilled and connects between the master cylinder connection chamber and the brake cylinder connection chamber; and a passage that is disposed in this passage and opens when the stepped piston is not in operation and connects the passage. And a shutoff valve for a brake fluid pressure increasing means for shutting off the passage when the stepped piston is actuated, wherein the operation control means controls the operation control chamber of the brake fluid pressure increasing means to the pressure source. In the event of a failure, the operation control means shuts off by communicating with either the reservoir for storing the working fluid of the pressure source or the reservoir of the master cylinder to open and shutting off and sealing from these reservoirs when the pressure source is normal. A brake booster system that is equipped with a valve. 2. The fluid pressure booster is a hydraulic booster, and the operation control means is formed in a housing for operation control means and is connected to the operation control chamber formed in the housing for operation control means. A first connection port, a second connection port formed in the operation control means housing and connected to the reservoir, and the operation for communicating the first and second connection ports formed in the operation control means housing. The passage of the control means, the shut-off valve for the operation control means which is provided in the passage of the operation control means and opens and closes the passage of the operation control means, and the hydraulic booster when the brake is operated in a normal state of the pressure source. And a valve closing piston that closes the shutoff valve for the operation control means by operating upon receipt of the working hydraulic pressure, and a valve opening that opens the shutoff valve for the operation control means when the brake is actuated when the pressure source fails. The brake booster system according to claim 1, further comprising a piston. 3. The fluid pressure booster is a negative pressure booster and the pressure source is a negative pressure source, and the operation control means includes an operation control means housing and a housing for the operation control means. A first connection port formed and connected to the operation control chamber; a second connection port formed in the operation control means housing and connected to the reservoir; and a first connection hole formed in the operation control means housing. And a passage for the operation control means communicating with the second connection port, the shutoff valve for the operation control means provided in the passage for the operation control means for opening and closing the passage for the operation control means, and when the negative pressure source is normal. A valve closing diaphragm piston that closes the shutoff valve for the operation control means by operating under the negative pressure of the negative pressure source, and a valve opening piston that opens the shutoff valve for the operation control means when the negative pressure source fails. The brake booster system according to claim 1, further comprising: 4. The operation control means housing is provided with a chamber facing one end of the valve opening piston and communicating with the master cylinder, the valve opening piston receiving pressure at one end of the master cylinder. The brake booster system according to claim 2 or 3, wherein the brake fluid pressure is set so as to open the shutoff valve for the operation control means when the brake is operated in the pressure source failure state. 5. A spring for urging the valve opening piston in a direction in which the shutoff valve is opened is provided, and the valve opening piston is actuated by the spring force of the spring when the brake is operated in the pressure source failure state. The brake booster system according to claim 2 or 3, wherein the shutoff valve for the operation control means is set to open. 6. The hydraulic booster is a hydraulic booster, and the operation control means is formed in a housing for operation control means and is connected to the operation control chamber formed in the housing for operation control means. A first connection port, a second connection port formed in the operation control means housing and connected to the reservoir, and the operation for communicating the first and second connection ports formed in the operation control means housing. A passage for the control means, a shut-off valve for the operation control means provided in the passage for the operation control means for opening and closing the passage for the operation control means, and for the operation control means by the spring force of a spring when the pressure source fails. The shutoff valve for the actuation control means is closed so that the shutoff valve for the actuation control means closes by opening the shutoff valve and actuating by receiving the actuation pressure of the pressure source when the pressure source is normal. The brake boosting system according to claim 1, further comprising a valve opening piston that releases the spring force of the gear. 7. The fluid pressure booster is a negative pressure booster and the pressure source is a negative pressure source, and the operation control means includes an operation control means housing and a housing for the operation control means. A first connection port formed and connected to the operation control chamber; a second connection port formed in the operation control means housing and connected to the reservoir; and a first connection hole formed in the operation control means housing. And a passage of the operation control means communicating with the second connection port, the shutoff valve for the operation control means provided in the passage of the operation control means for opening and closing the passage of the operation control means, and the failure of the negative pressure source. At the same time, the shut-off valve for the operation control means is opened by the spring force of the spring, and the shut-off valve for the operation control means is closed by being actuated by receiving the negative pressure of the negative pressure source when the negative pressure source is normal. The brake booster system according to claim 1, further comprising a valve opening diaphragm piston that releases the control means shutoff valve from the spring force of the spring. 8. A check valve provided with another passage that connects the operation control chamber and the reservoir, and allows only the flow of the working fluid from the reservoir toward the operation control chamber in the other passage. The brake booster system according to any one of claims 1 to 6, further comprising: