JPH0826096A - Brake device - Google Patents

Abstract

PURPOSE:To prevent the operation delay of a boosting mechanism, by immediately opening and closing an opening/closing valve, when a hydraulic booster or its hydraulic pressure source fails. CONSTITUTION:When a hydraulic booster operates normally, a boosting mechanism 7 does not operate, while, if the hydraulic booster or a hydraulic pressure source fails, the boosting mechanism 7 operates. Accordingly, the hydraulic booster or the hydraulic pressure source fails, the hydraulic pressure which acts into the fourth pressure chamber 33 becomes zero. and an opening/closing valve 29 is closed by the urging force of a spring 32, and the communication state between a master cylinder 3 and a front wheel cylinder 5 is cut off. Succeedingly to this state, the hydraulic pressure in the master cylinder 3 is boosted by the boosting mechanism 7 when a brake pedal is stepped, and the hydraulic pressure is transmitted to the front wheel cylinder 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake device, and more particularly to a brake device having a pressure increasing mechanism for boosting the brake hydraulic pressure of a master cylinder when the hydraulic booster fails.

[0002]

2. Description of the Related Art Conventionally, as a brake device, a master cylinder that applies brake fluid pressure to a wheel cylinder,
A hydraulic booster provided between the brake pedal and the master cylinder for boosting the pedaling force of the brake pedal at a predetermined ratio and transmitting the boosted force to the master cylinder when the brake pedal is depressed; The brake fluid passage that connects the cylinder and the master cylinder is installed, and the pressure booster mechanism that boosts the brake fluid pressure of the master cylinder and transmits it to the wheel cylinders when actuated, and the hydraulic booster are lost. A device provided with a control valve that operates the pressure increasing mechanism when it falls is known (for example, Japanese Patent Publication No. 6-2901).
1). In such a conventional brake device, the hydraulic pressure of the power chamber of the hydraulic booster is compared with the hydraulic pressure of the master cylinder,
When the hydraulic pressure in the power chamber of the hydraulic booster becomes lower than the hydraulic pressure in the master cylinder, the control valve switches the flow path of the brake fluid to operate the pressure increasing mechanism. As a result, the brake fluid pressure in the master cylinder is doubled by the pressure boosting mechanism, so that the increased brake fluid pressure is transmitted to the wheel cylinders. As a result, even when the hydraulic booster loses its boosting function, the brake operation can be reliably obtained.

[0003]

However, in the above conventional apparatus, when the hydraulic booster fails and the hydraulic pressure in the power chamber of the hydraulic booster does not become completely zero, the control valve described above is not used. In this case, the brake pedal is continuously depressed and the hydraulic pressure in the master cylinder becomes higher than the hydraulic pressure in the power chamber of the hydraulic booster before the pressure increasing mechanism is activated. Therefore, in the above-mentioned conventional device, even if the hydraulic booster fails, if the hydraulic pressure remains in the power chamber of the hydraulic booster, the operation of the pressure increasing mechanism is delayed. .

[0004]

[Means for Solving the Problems] In view of such circumstances,
The present invention is provided between a master cylinder that applies brake fluid pressure to a wheel cylinder, a brake pedal and the master cylinder, and doubles the pedaling force of the brake pedal at a predetermined ratio when the brake pedal is depressed. A hydraulic booster that applies force to the master cylinder and a brake fluid passage that connects the wheel cylinder and the master cylinder to each other is installed.When actuated, the brake fluid pressure in the master cylinder is increased. In a brake device including a pressure increasing mechanism that transmits to a wheel cylinder and a control valve that operates the pressure increasing mechanism when the hydraulic booster fails, the control valve is a spring set to a predetermined set load. Of the hydraulic booster operated from the side opposite to the urging direction of the spring while being moved to the operating position by the The valve member is provided with a valve member that is moved to a non-actuated position by the hydraulic pressure of the force chamber or the hydraulic pressure of the hydraulic pressure source of the hydraulic booster device to render the pressure increasing mechanism inoperable. Provided is a brake device which is moved from a non-actuated position to an actuated position when the urging force by the hydraulic pressure of the power chamber of the device or the hydraulic pressure of the hydraulic pressure source of the hydraulic booster becomes smaller than the urging force of the spring. To do.

[0005]

According to this structure, the hydraulic booster or the hydraulic pressure source of the hydraulic booster fails, and the hydraulic pressure of the power chamber of the hydraulic booster or the hydraulic booster of the hydraulic booster is lost. When the urging force of the hydraulic pressure of the hydraulic pressure source becomes smaller than the urging force of the spring, the control valve operates and the pressure increasing mechanism becomes operable. Therefore,
Since the pressure boosting mechanism operates immediately when the hydraulic pressure of the master cylinder is generated, it is possible to prevent the delay in the operation of the pressure boosting mechanism when the hydraulic booster or the hydraulic pressure source of the hydraulic booster fails.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. In FIG. 1, reference numeral 1 denotes a brake pedal, which is connected to an input shaft of a hydraulic booster 2 having a conventionally known structure. The output shaft of the hydraulic booster 2 is connected to the piston of the master cylinder 3, and when the brake pedal 1 is depressed, the hydraulic booster 2 boosts the pedaling force of the brake pedal 1 at a predetermined ratio. , Is transmitted to the piston of the master cylinder 3. Master cylinder 3 of this embodiment
Is a tandem type, and transmits the brake fluid pressure generated when the brake pedal 1 is depressed to the front wheel cylinder 5 via the brake fluid passage 4 and at the same time via the brake fluid passage 6 to a rear wheel (not shown). It is designed to be transmitted to the cylinder. The brake fluid passage 4 is provided with a pressure increasing mechanism 7 and a control valve 8 which will be described in detail later. A pressure increasing mechanism 7 and a control valve 8 are also provided in the brake fluid passage 6 on the rear side, but the description is omitted because it is the same as that provided in the brake fluid passage 4 on the front side. When the pressure increasing mechanism 7 is operated by the control valve 8, the brake fluid pressure generated in the master cylinder 3 is increased and transmitted to the front wheel cylinder 5. The hydraulic booster 2 is connected to a pump 13 operated by an accumulator 12 and a motor 18 by a liquid passage 11, and the brake fluid stored in a reservoir 14 is supplied to the accumulator 12 by the pump 13. It is fed to the power chamber of the hydraulic booster 2. The brake fluid discharged from the hydraulic booster 2 is returned to the reservoir 14 via the fluid passage 15.
Reference numeral 17 is a check valve that holds the pump discharge pressure. In this embodiment, the hydraulic pressure of the accumulator 12 also acts on the pressure increasing mechanism 7 via the brake fluid passage 16. As shown in FIG. 2, the pressure increasing mechanism 7 is provided with a casing 21 having a stepped hole 21A, and a stepped piston 22 is held in the stepped hole 21A in a liquid-tight manner so that the stepped piston 22 can slide. It is fitted. In this embodiment, the control valve 8 is incorporated in the stepped piston 22. The end surface 22b of the large diameter portion 22a of the stepped piston 22, the wall surface of the casing 21 facing the end surface 22b, and the inner portion of the large diameter hole 21a of the stepped hole 21A define a first pressure chamber 23. The first pressure chamber 23 communicates with the master cylinder 3 via the axial hole of the casing 21 and the brake fluid passage 4 connected thereto. Thereby, the first pressure chamber 23
Brake fluid is introduced into the cylinder, and the brake fluid pressure generated in the master cylinder 3 acts. The end surface 22d of the small diameter portion 22c of the stepped piston 22, the wall surface of the casing 21 facing the end surface 22d, and the inner portion of the small diameter hole 21b of the stepped hole 21A define a second pressure chamber 24. The pressure chamber 24 communicates with the front wheel cylinder 5 via the axial hole of the casing 21 and the brake fluid passage 4 connected thereto. As a result, the brake fluid pressure of the front wheel cylinder 5 acts on the second pressure chamber 24. The stepped end surface 22e of the stepped piston 22, the stepped end surface of the stepped hole 21A facing the stepped piston 22 and the inner side of the large diameter hole 21a define a third pressure chamber 25. 25 is a casing 21
Is communicated with the accumulator 12 via a radial passage 21c provided in the vehicle and a brake fluid passage 16 connected thereto. Therefore, the hydraulic pressure of the accumulator 12 is introduced into the third pressure chamber 25. The third pressure chamber 2
5, the stepped end face of the stepped hole 21A and the stepped piston 22
Of the return spring 26 over the step end face 22e of
The stepped piston 22 is positioned at a non-operating position shown in the drawing in which the end surface 22b of the stepped piston 22 contacts the wall surface of the casing by the return spring 26. The stepped piston 22 has an axially penetrating communication passage 2
2f is provided, and the first pressure chamber 23 and the second pressure chamber 24 are communicated with each other through the communication passage 22f. A stepped hole 22g is formed in the shaft portion of the stepped piston 22, and a valve member 27 having a large diameter portion 27a in the axial center is slidably fitted in the stepped hole 22g. are doing. Valve member 2
One end 27b of 7 faces the second pressure chamber 24, and the other end 27c of the valve member 27 is located in the communication passage 22f. Then, the valve member 2 located in the communication passage 22f
A ball is embedded in the end surface of the other end 27c of the seat 7, and the ball serves as a seat portion 27d. The seat portion 27d is provided at a position facing the seat portion 27d in the communication passage 22f.
It forms a valve seat 28 that d contacts and separates. The seat portion 27d and the valve seat 28 constitute an opening / closing valve 29 that opens / closes the communication passage 22f. In addition, the cross-sectional areas d1 and d2 of both ends 27b and 27c of the valve member 27 are the same,
The cross-sectional area of the seat portion 27d seated on the valve seat 28 is equal to the end portion 27.
It is smaller than the cross-sectional area d1 of c. Stepped hole 22 that is closer to the second pressure chamber 24 than the large diameter portion 27a of the valve member 27.
A spring chamber 31 is provided inside g. A spring 32 set to a predetermined set load is elastically mounted in the spring chamber 31, whereby the valve member 27 is biased toward the upper side to close the on-off valve 29. The spring chamber 31 is in communication with the atmosphere via a passage 22h provided in the stepped piston 22 and a passage 21d provided in the casing 21. The spring chamber 31 may be communicated with the reservoir 14 instead of being open to the atmosphere. An inward portion of the stepped hole 22g on the first pressure chamber 23 side of the large diameter portion 27a is a fourth pressure chamber 33,
The fourth pressure chamber 33 communicates with the third pressure chamber 25 via the passage 22i of the stepped piston 22. Therefore, the pressure of the accumulator 12 is constantly acting on the fourth pressure chamber 33, and the valve member 27 is resisted against the biasing force of the spring 32.
Are pushed downward, and therefore the on-off valve 29
Is open. Further, in the present embodiment, the communication passage 22f provided in the stepped piston 22 as described above, the valve member 2
The control valve 8 includes the on-off valve 7, the on-off valve 29, the spring 32, and the fourth pressure chamber 33. In the above configuration, the hydraulic booster 2 and the accumulator 1 serving as the hydraulic pressure source
Since the hydraulic pressure of the accumulator 12 acts on the fourth pressure chamber 33 when the pump 2 and the pump 13 are operating normally, the spring 32 is compressed and the on-off valve 29 is opened. In this state, both ends 27b, 2 of the valve member 27 are
Since the cross-sectional areas d1 and d2 of 7c are the same, the valve member 27 moves downward only by the relationship between the downward urging force of the accumulator 12 acting on the fourth pressure chamber 33 and the urging force of the spring 32. It has been pushed down. Therefore, the opening / closing valve 29 is opened, and the first pressure chamber 23 and the second pressure chamber 24 communicate with each other through the communication passage 22f, and thus the master cylinder 3 and the front wheel cylinder 5 communicate with each other. Further, the stepped piston 22 is positioned at the non-actuated position in the figure by the return spring 26. When the brake pedal 1 is stepped on from this state, the hydraulic booster 2 boosts the stepping force of the brake pedal 1 at a predetermined ratio and transmits the boosted force to the master cylinder 3. As a result, brake fluid pressure is generated in the master cylinder 3, and the brake fluid pressure is
Via the brake fluid passage 4 upstream of the pressure increasing mechanism 7, the first pressure chamber 23 of the pressure increasing mechanism 7, the communication passage 22f, the second pressure chamber 24 and the brake fluid passage 4 downstream of the pressure increasing mechanism 7. Is transmitted to the front wheel cylinder 5. As a result, normal braking operation can be obtained. In addition,
Even when the brake pedal 1 is depressed after reaching the full load point where the boosting ratio of the hydraulic booster 2 becomes 1, the on-off valve 29 remains open, so that the master cylinder 3 is connected to the brake fluid passage 4 and the brake fluid passage 4. It communicates with the front wheel cylinder 5 via a pressure mechanism 7. Therefore, even if the stepped piston 22 compresses the return spring 26 and displaces it from the non-actuated position, the pressure boosting mechanism 7 is not actuated. Compared to the normal state, the accumulator 12 and the pump 13, which are hydraulic pressure sources, are out of order and the hydraulic booster 2
When the boosting function due to is no longer obtained, the hydraulic pressure of the accumulator 12 acting on the third pressure chamber 25 and the fourth pressure chamber 33 decreases to zero or close to that. Therefore, the upward biasing force of the spring 32 is greater than the hydraulic biasing force of the accumulator 12 that acts on the fourth pressure chamber 33 to push down the valve member 27.
Therefore, the valve member 27 is pushed upward with respect to the stepped piston 22, so that the seat portion 27d is seated on the valve seat 28 and the on-off valve 29 is closed. Therefore, communication between the master cylinder 3 and the front wheel cylinder 5 is blocked. When the brake pedal 1 is depressed from this state, the boosting function of the hydraulic booster 2 cannot be obtained, so the pedaling force of the brake pedal 1 is transmitted to the master cylinder 3 as it is. As a result, brake fluid pressure is generated in the master cylinder 3, and the brake fluid pressure acts on the first pressure chamber 23 of the pressure increasing mechanism 7. As a result, the stepped piston 22 is pushed down against the repulsive force of the return spring 26, and accordingly the ratio of the cross-sectional area of the small diameter portion 22c to the cross-sectional area of the large diameter portion 22a of the stepped piston 22 is reduced. The brake fluid pressure in the second pressure chamber 24 is increased by a corresponding amount, and the increased brake fluid pressure is transmitted to the front wheel cylinder 5. As described above, in this embodiment, the hydraulic pressure source of the hydraulic booster 2 fails and the hydraulic booster 2 is damaged.
When the boosting function due to is no longer obtained, the fourth pressure chamber 3
Since the hydraulic pressure of the accumulator 12 acting on 3 decreases and the opening / closing valve 29 is closed by the urging force of the spring 32,
After that, when the brake pedal 1 is depressed, the pressure increasing mechanism 7 is immediately activated. Therefore, the hydraulic booster 2
It is possible to prevent the operation delay of the pressure increasing mechanism 7 from occurring at the time of the failure of. Further, as described above, even if the hydraulic booster 2 reaches the full load point in the normal state, since the opening / closing valve 29 of the pressure increasing mechanism 7 is opened, the pressure increasing action by the pressure increasing mechanism 7 cannot be obtained. . Therefore, in this embodiment, it is not necessary to provide the brake fluid passage 16 with a limiter for preventing the pressure boosting action of the pressure boosting mechanism 7 after the hydraulic booster 2 reaches the full load point. (Second Embodiment) Next, FIG. 3 shows a second embodiment of the present invention. While the spring chamber 31 is opened to the atmosphere or the reservoir 14 in the first embodiment, this second embodiment
In the embodiment, the spring chamber 131 is configured to communicate with the second pressure chamber 124 via the second opening / closing valve 140. That is, in the second embodiment, the plug 141 having the shaft portion formed with the stepped through hole is screwed to the shaft portion of the small diameter portion 122c of the stepped piston 122, and the entire plug 141 is included. The stepped piston 122 is used. And
The large diameter portion 127a of the valve member 127 is fitted in the large diameter hole 141a in the through hole of the plug 141, and the fourth pressure is applied to the first pressure chamber 123 side from the large diameter portion 127a as in the first embodiment. The chamber 133 is configured. Also, the large diameter portion 127
a lower step end surface 127e in a, the step end surface 141b of the plug 141 facing the lower step end surface 127e, and the large diameter hole 141.
A spring chamber 131 is formed by the inner part of a, and a spring 132 set to a predetermined set load is elastically mounted on both step end surfaces 127e and 141b. This allows
The valve member 127 is biased toward the upper side. Spring chamber 1
A ball having the same diameter as that of the other on-off valve 129 is embedded in the end surface of the end portion 127b of the valve member 127 located inside 31, and the seat portion 127f is formed by the ball. Further, the plug 141 facing the seat portion 127f
The seat portion 127f is formed with a valve seat 142 at the boundary between the large diameter hole 141a and the small diameter hole 141c, and the seat portion 127f and the valve seat 142 constitute the second on-off valve 140. There is. Both ends 127 of the valve member 127
The cross-sectional areas of b and 127c are the same, and the cross-sectional areas of both seat portions 127d and 127f are also set to be the same.
Further, in this embodiment, the return spring 126 is provided inside the second pressure chamber 124. Other configurations are the same as the configurations of the above-described first embodiment, and the members corresponding to the first embodiment have the member numbers converted from 100. In the second embodiment having such a configuration, when the hydraulic booster and the accumulator 112 or the like serving as the hydraulic pressure source are operating normally, the accumulator 112 is
Since the hydraulic pressure of the spring acts on the fourth pressure chamber 133, the spring 1
32 is compressed and the on-off valve 140 is closed, while the other on-off valve 129 is open. Further, the stepped piston 122 is positioned at the inoperative position in the drawing by the return spring 126. Then, when the brake pedal is depressed from this state, the hydraulic booster boosts the pedaling force of the brake pedal at a predetermined ratio and transmits the boosted force to the master cylinder 103, and the brake fluid pressure generated in the master cylinder 103 is The pressure is transmitted to the front wheel cylinder without being increased in pressure by the pressure increasing mechanism 107. As a result, normal braking operation can be obtained. Even if the brake pedal is depressed after reaching the full load point where the boosting ratio of the hydraulic booster reaches 1, the on-off valve 129 remains open. Therefore, if the stepped piston 1
22 compresses the return spring 126 to form the stepped hole 1
Even if it slides in 21A, the pressure increasing mechanism 107 is not operated. The accumulator acting on the third pressure chamber 125 and the fourth pressure chamber 133 when the accumulator 112 serving as a hydraulic pressure source and the pump fail and the boosting function of the hydraulic pressure booster cannot be obtained compared to the normal state. The hydraulic pressure at 112 drops to zero or close to it. Therefore, the upward biasing force of the spring 132 is greater than the hydraulic biasing force of the accumulator 112 acting on the valve member 127. Therefore,
Since the valve member 127 is pushed upward with respect to the stepped piston 122, the seat portion 127d is seated on the valve seat 128 and the opening / closing valve 129 is closed, while the second opening / closing valve 140 is closed.
Is released. As a result, the communication state between the first pressure chamber 123 and the second pressure chamber 124 is blocked, so that the communication between the master cylinder 103 and the front wheel cylinder 105 is blocked. Further, as the second opening / closing valve 140 is opened, the spring chamber 131 and the second pressure chamber 124 communicate with each other, and the hydraulic pressure of the second pressure chamber 124 (the hydraulic pressure of the front wheel cylinder 105) is changed to the valve member. It acts on 127. Therefore, not only the biasing force of the spring 132 but also the third pressure chamber 1
The biasing force of the hydraulic pressure of 25 acts on the valve member 127, and the on-off valve 129 is reliably closed. When the brake pedal is depressed from this state, the brake fluid pressure of the master cylinder 103 increases as in the first embodiment described above.
The pressure is increased by 07, and the front wheel cylinder 1
It is transmitted to 05. It is obvious that the second embodiment having such a configuration can also obtain the same effects as the first embodiment described above. (Third Embodiment) Next, FIG. 4 shows a third embodiment of the present invention. In the above-described both embodiments, the control valves 8 and 108 are incorporated in the stepped pistons 22 and 122, whereas in the third embodiment, the switching valve 250 that constitutes a part of the control valve 208 is the casing 221. It is provided outside of. That is, in the third embodiment, only one stepped through hole 222f is bored in the shaft portion of the stepped piston 222, and the first pressure chamber 223 and the second pressure chamber 224 communicate with each other through the through hole 222f. It is used as a communication passage. Then, the spherical valve element 22 is formed in the enlarged diameter portion of the through hole 222f.
7 is housed, and the valve body 227 and the valve seat 228 that comes in contact with and separates from the valve body 227 constitute an on-off valve 229. A protrusion 221e is formed on the wall surface of the casing 221 facing the first pressure chamber 223, and the tip of the protrusion 221e faces the valve body 227. In the non-actuated state of the pressure boosting mechanism 207, the end surface 222b of the large diameter portion 222a of the stepped piston 122 is moved to the casing 2 by the litter spring 226.
21 is in contact with the wall surface of the valve body 21, and accordingly, the tip of the protruding portion 221e penetrates the valve seat 228, and
7 is separated from the valve seat 228. Therefore, the on-off valve 229 is opened and the master cylinder 203 and the front wheel cylinder 205 are in communication. Further, in this embodiment, the hydraulic pressure of the master cylinder 203 is introduced into the third pressure chamber 226 via the brake fluid passage 251, and the brake fluid passage 251 has an end portion of the brake fluid passage 252 communicating with the reservoir 214. Are connected via a switching valve 250. An accumulator may be connected to the brake fluid passage 252 instead of the reservoir 214, or a hydraulic booster may be connected. Further, instead of introducing the hydraulic pressure of the master cylinder 203 into the third pressure chamber 226, the hydraulic pressure of the front wheel cylinder 205 may be introduced into the third pressure chamber 226. This switching valve 25
0 is slidably provided in a housing (not shown) and is biased upward by a spring 253 set to a predetermined set load, and at the same time, the hydraulic pressure of the accumulator 212 introduced into the housing. Is urged toward the side opposite to the urging direction of the spring 253. Further, in this third embodiment, the stepped piston 222
The stepped hole 222f, the opening / closing valve 229, and the switching valve 250 constitute the control valve 208. The other configurations are the same as the configurations of the first embodiment, and the members corresponding to the first embodiment have the member numbers converted from 200 respectively. In the third embodiment configured as described above, the hydraulic booster and the accumulator 21 serving as the hydraulic pressure source thereof.
In the state in which the second and the like are operating normally, the hydraulic pressure of the accumulator 212 acts on the switching valve 250 to compress the spring 253, as shown in FIG. Therefore, not only in the first pressure chamber 223 and the second pressure chamber 224, but also in the third pressure chamber 225, the brake fluid passage 251 and the switching valve 2 are provided.
The hydraulic pressure of the master cylinder 203 acts via 50. In this state, since the hydraulic pressures of the master cylinder 203 acting on the stepped piston 222 from both upper and lower sides are the same, the stepped piston 222 is in the inoperative position in the drawing,
The on-off valve 229 is open. Therefore, when the master cylinder 203 and the front wheel cylinder 205 communicate with each other and the brake pedal is depressed from this state, normal brake operation can be obtained. Compared to the normal state, when the accumulator 212 and the pump, which are hydraulic pressure sources, fail and the boosting function of the hydraulic pressure booster cannot be obtained, the hydraulic pressure of the accumulator 212 acting on the switching valve 250 becomes zero or The spring 2 has a lower pressure than the biasing force that pushes the switching valve 250 downward.
Since the biasing force of 52 becomes larger, the flow path is switched by the switching valve 250. As a result, communication between the third pressure chamber 225 and the master cylinder 203 is blocked, while communication between the third pressure chamber 225 and the reservoir 214 causes the hydraulic pressure in the third pressure chamber 225 to become zero. Therefore, the stepped piston 222 moves the return spring 22 due to the hydraulic pressure of the master cylinder 203 acting on the first pressure chamber 223.
6, the valve body 227 is separated from the tip of the protruding portion 221e, and while it is seated on the valve seat 228, the on-off valve 229 is closed. As a result, the communication state between the first pressure chamber 223 and the second pressure chamber 224 is blocked, and thus the communication between the master cylinder 203 and the front wheel cylinder 205 is blocked. Therefore, if the brake pedal is depressed from this state,
As in the first embodiment described above, the brake fluid pressure of the master cylinder 203 is increased by the pressure increasing mechanism 207 and transmitted to the front wheel cylinder 205. With the configuration of the third embodiment as well, it is possible to obtain the same operational effects as those of the above-described embodiments. Although the hydraulic pressures of the accumulators 12, 122 are introduced into the fourth pressure chambers 33, 133 via the third pressure chambers 25, 125 in the first and second embodiments, the hydraulic pressures of the accumulators 12, 122 are not shown. Instead of, the hydraulic pressure of the hydraulic booster may be introduced.
Also in the third embodiment, the hydraulic pressure of the hydraulic booster may be introduced instead of the hydraulic pressure of the accumulator 212 acting on the switching valve 250. In that case, the springs 32, 13 are more than the case where the hydraulic pressure of the accumulator is introduced.
The set load of 2, 253 is reduced so that the control valves 8, 108, 208 are held in the non-actuated position by the power chamber pressure immediately after the boosting of the hydraulic booster is started. Therefore, although the control valves 8, 108 and 208 are in the operating position when the hydraulic booster is in the non-operating state, when the hydraulic booster is operating normally, the power chamber pressure is the same as in the first and second embodiments. 3 pressure chambers 25,225
And the fourth pressure chamber 33, 133 is introduced, the control valve 8, 108 moves to the non-actuated position, the on-off valve 29, 129 is opened, and the pressure increasing mechanism 7, 107 does not operate. Further, in the third embodiment, the switching valve 208 switches to introduce the master cylinder pressure or the wheel cylinder pressure into the third pressure chamber 225, so that the pressure increasing mechanism 207 does not operate similarly. When the hydraulic pressure source fails and the accumulator pressure becomes 0, the power chamber pressure is 0 even if the hydraulic booster operates, and the control valves 8, 108, 20
Since 8 is in the operating position as it is, the pressure increasing mechanism operates in all of the first, second and third embodiments.

As described above, according to the present invention, it is possible to prevent an operation delay of the pressure boosting mechanism when the hydraulic booster or its hydraulic pressure source fails.

[Brief description of drawings]

FIG. 1 is an overall system diagram showing an embodiment of the present invention.

FIG. 2 is a sectional view of the constituent member shown in FIG.

FIG. 3 is a sectional view showing another embodiment of the present invention.

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

[Description of sign]

1 ... Brake pedal 2 ... hydraulic pressure booster 3 ... master cylinder 5 ... front wheel cylinder 7 ... pressure increasing mechanism 8 ... control valve 29 ... open / close valve 32 ... spring

Claims (4)

[Claims] 1. A master cylinder that applies brake fluid pressure to a wheel cylinder, and a brake pedal, which is provided between the brake pedal and the master cylinder so that when the brake pedal is depressed, the depression force of the brake pedal is set at a predetermined ratio. A hydraulic pressure booster that boosts the power and transmits it to the master cylinder is installed in the brake fluid passage that connects the wheel cylinder and the master cylinder, and when actuated, increases the brake fluid pressure in the master cylinder. In a brake device including a pressure increasing mechanism that transmits to a wheel cylinder and a control valve that operates the pressure increasing mechanism when the hydraulic booster fails, the control valve is set to a predetermined set load. The hydraulic booster is moved to the operating position by the spring to make the pressure increasing mechanism operable, and is actuated from the side opposite to the urging direction of the spring. Is provided with a valve member that is moved to a non-operating position by the hydraulic pressure of the power chamber or the hydraulic pressure of the hydraulic pressure source of the hydraulic booster to render the pressure increasing mechanism inoperable. When the urging force by the hydraulic pressure of the power chamber of the force device or the hydraulic pressure of the hydraulic pressure source of the hydraulic booster becomes smaller than the urging force of the spring, it is moved from the non-operating position to the operating position. Brake device. 2. The step-up mechanism includes a stepped piston slidably fitted in a stepped through hole formed in a casing while maintaining liquid tightness, and a large diameter of the stepped piston in the casing. A first pressure chamber formed in the casing and communicating with the master cylinder, a second pressure chamber formed in the small diameter portion of the stepped piston in the casing and communicating with the wheel cylinder, and a stepped piston in the casing. And a third pressure chamber that is formed at a position facing the step end surface of the stepped portion and communicates with the power chamber of the hydraulic booster or the hydraulic pressure source of the hydraulic booster, and returns the stepped piston to the non-operating position. A return spring, the control valve is formed on the stepped piston,
A communication passage that connects the pressure chamber and the second pressure chamber, and a stepped piston that is slidably fitted while maintaining liquid tightness, has a large-diameter portion on the axial center side, and has an axial direction. A valve member having one end face facing the second pressure chamber and the other end face facing the communication passage; and the control valve includes a seat portion formed on the end face of the valve member. An on-off valve that is formed of a valve seat portion formed in the communication passage and opens and closes the communication passage, a spring chamber formed on the second pressure chamber side of the large diameter portion of the valve member in the stepped piston, and this spring chamber A spring for energizing the valve member in the axial direction to urge the seat portion toward the valve seat, a passage for communicating the spring chamber with the atmosphere or a reservoir, and a valve in the stepped piston. The fourth pressure chamber formed on the first pressure chamber side of the large diameter portion of the member and the fourth pressure chamber The brake device according to claim 1, further comprising: a passage communicating with the third pressure chamber. 3. The step-up mechanism includes a stepped piston slidably fitted in a stepped through hole formed in a casing while maintaining liquid tightness, and a large diameter of the stepped piston in the casing. A first pressure chamber formed in the casing and communicating with the master cylinder, a second pressure chamber formed in the small diameter portion of the stepped piston in the casing and communicating with the wheel cylinder, and a stepped piston in the casing. And a third pressure chamber that is formed at a position facing the step end surface of the stepped portion and communicates with the power chamber of the hydraulic booster or the hydraulic pressure source of the hydraulic booster, and returns the stepped piston to the non-operating position. A return spring, the control valve is formed on the stepped piston,
A communication passage that connects the pressure chamber and the second pressure chamber, and a stepped piston that is slidably fitted while maintaining liquid tightness, has a large-diameter portion on the axial center side, and has an axial direction. A shaft of a stepped piston in which a first seat portion formed on one end face is opposed to a first valve seat formed on the communication passage, and a second seat portion formed on the other end face communicates with a second pressure chamber. A valve member facing a second valve seat provided in the direction hole, and the control valve includes a first seat portion and a first valve seat and opens and closes the communication passage. An on-off valve, a second on-off valve configured to include the second seat portion and a second valve seat, and which opens and closes an axial hole of the stepped piston communicating with the second pressure chamber; and a valve in the stepped piston. A fourth pressure chamber formed on the first opening / closing valve side of the large diameter portion of the member and the fourth pressure chamber communicated with the third pressure chamber. And a passage formed in the stepped piston on the second opening / closing valve side of the large diameter portion of the valve member, and communicates with the second pressure chamber via the second opening / closing valve and the axial hole of the stepping piston. The brake device according to claim 1, further comprising: a spring chamber that is opened, and the spring that is housed in the spring chamber and biases the first seat portion of the valve member toward the first valve seat. 4. The step-up mechanism includes a stepped piston slidably fitted in a stepped through hole formed in a casing while maintaining liquid tightness, and a large diameter of the stepped piston in the casing. A first pressure chamber formed in the casing and communicating with the master cylinder, a second pressure chamber formed in the small diameter portion of the stepped piston in the casing and communicating with the wheel cylinder, and a stepped piston in the casing. And a third pressure chamber that is formed at a position facing the step end surface of the stepped portion and communicates with the power chamber of the hydraulic booster or the hydraulic pressure source of the hydraulic booster, and returns the stepped piston to the non-operating position. A return spring, the control valve is formed on the stepped piston,
A communication passage that connects the pressure chamber and the second pressure chamber, and a communication passage that is provided in the stepped piston and opens the communication passage when the stepped piston is in the non-operation position, and the stepped piston is in the non-operation position. An on-off valve that closes the communication passage when it is moved from, and a third pressure chamber that is slidably provided in the housing and that communicates with the master cylinder or wheel cylinder when it is in the non-operating position The valve member for communicating the third pressure chamber with the power chamber of the hydraulic booster, the hydraulic pressure source of the hydraulic booster, or the reservoir when the third pressure chamber is located. Brake device.