JPH0858560A - Brake device - Google Patents

Abstract

PURPOSE: To prevent operation delay of a pressure boosting mechanism when a liquid pressure boosting device or the liquid pressure source is broken down by immediately seating a valve body onto a valve seat so as to close a communicating passage, when the liquid pressure boosting device or the liquid pressure source is broken down. CONSTITUTION: When a liquid pressure boosting device or the liquid pressure source is broken down, liquid pressure applied to a third pressure chamber 25 becomes zero, and a valve body 28 is seated onto a valve seat 27 so as to close a communicating passage 22f by the energization force of a compression spring 32 having larger set load than that of a compression spring 34. Hereby, communication between a master cylinder 3 and a front wheel cylinder 5 is intercepted. When a brake pedal is stepped in from this condition, a stepped piston 22 is pushed down, and hence the liquid pressure in the master cylinder 3 is boosted by a pressure boosting mechanism 7 and 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).
No. 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, and the hydraulic pressure of the power chamber of the hydraulic booster is higher than the hydraulic pressure of the master cylinder. When the pressure becomes low, the flow path of the brake fluid is switched by the control valve 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 of the power chamber of the hydraulic booster does not become completely zero, there is residual pressure. Is
The control valve operates the pressure increasing mechanism after the brake pedal is continuously depressed and the hydraulic pressure in the master cylinder becomes higher than the residual pressure in the power chamber of the hydraulic booster.
Therefore, the above conventional device has a drawback that the operation of the pressure boosting mechanism is delayed when the hydraulic booster fails and there is residual pressure in the power chamber of the hydraulic booster.

[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. A step-up through hole formed in the casing, the pressure-increasing mechanism being transmitted to the wheel cylinder, and the control valve for activating the pressure-increasing mechanism when the hydraulic booster fails. A stepped piston slidably fitted to the stepped piston, and a first pressure chamber formed on the large diameter side of the stepped piston in the casing and communicating with the master cylinder. Second communicating the wheel cylinder is formed on the small diameter portion of the stepped piston in the casing
A pressure chamber and a third pressure chamber which is formed at a position facing the stepped end face of the stepped piston in the casing and communicates with a power chamber of the hydraulic booster or a hydraulic pressure source of the hydraulic booster. ,
In a brake device comprising a return spring for returning the stepped piston to a non-operating position, and the control valve provided on the stepped piston of the pressure increasing mechanism, the control valve is formed on the stepped piston. A communication passage communicating the first pressure chamber and the second pressure chamber, an annular valve seat formed at a predetermined position of the communication passage, and a movable passage provided in the communication passage for contacting and separating from the valve seat. A valve body that opens and closes the communication passage by means of a first spring having a predetermined set load, which is disposed in the communication passage and engages with the valve body so that the valve body is seated on the valve seat. The biasing first pressing member is slidably provided at a predetermined position of the stepped piston on the side opposite to the first pressing member with the valve body interposed therebetween, and one end of the valve is opposite to the first pressing member. To the hydraulic pressure of the third pressure chamber that is engaged with the body and acted on the other end A second pressing member for urging the valve body in the direction of separating from the valve seat, and a predetermined set load, and in the direction of separating the valve body from the valve seat via the second pressing member. It is composed of a second spring for urging. A second aspect of the present invention is provided between a master cylinder that applies brake fluid pressure to a wheel cylinder, and a brake pedal and the master cylinder. When the brake pedal is depressed, the pedal effort of the brake pedal is set to a predetermined value. The hydraulic pressure booster that boosts the speed of the master cylinder and transmits it to the master cylinder, and the brake fluid passage that connects the wheel cylinder and the master cylinder to each other. And a control valve that activates the pressure boosting mechanism when the hydraulic booster fails, and the pressure boosting mechanism is installed in the casing. A stepped piston that is slidably fitted in a through hole with a liquid tightness, and a stepped piston that is formed on the large diameter side of the stepped piston in the casing and that communicates with the master cylinder. A pressure chamber, a second pressure chamber formed on the small diameter side of the stepped piston in the casing and communicating with the wheel cylinder, and formed at a position facing the stepped end surface of the stepped piston in the casing, It is composed of a third pressure chamber communicating with the power chamber of the hydraulic booster or the hydraulic pressure source of the hydraulic booster, and a return spring for returning the stepped piston to the non-operating position, and the control valve is increased. In the braking device provided on the stepped piston of the pressure mechanism,
The control valve is slidably fitted in a stepped communication hole that is bored in the stepped piston and connects the first pressure chamber and the third pressure chamber to each other, and is kept liquid-tight in the communication hole. And a stepped valve member in which the hydraulic pressure of the first pressure chamber is applied to one end face and the hydraulic pressure of the third pressure chamber is applied to the other end face, and the stepped valve member is formed on this valve member Is formed in the stepped piston and has a first communication passage that communicates with the first pressure chamber and the other end opens at a predetermined axial position on the outer peripheral surface, and has one end in the axial direction on the inner peripheral surface of the communication hole. A second communication passage that opens at a predetermined position and communicates with the communication hole, and the other end communicates with the second pressure chamber, and the valve member is axially biased, and the valve member has a hydraulic pressure in the third pressure chamber. When the fluid pressure of the third pressure chamber is not acting on the valve member, the first communication passage and the second communication passage are communicated with each other when Member is a material obtained by composed of a spring to block the communication between the first communication passage and second communication passage is moved in the axial direction.

[0005]

According to the first aspect of the invention, when the hydraulic booster or the hydraulic pressure source of the hydraulic booster fails, the hydraulic pressure in the third pressure chamber becomes zero, so that the second pressing member is 2 The urging force of the spring alone urges the valve element in the direction of separating it. At this time, since the urging force of the first spring in the direction of seating the valve body is larger than the urging force of the second spring in the direction of separating the valve body, the valve body is seated on the valve seat. Then, the communication passage is closed. That is, the communication state between the first pressure chamber and the second pressure chamber is cut off.
Then, when the brake pedal is depressed from this state and the hydraulic pressure in the master cylinder rises, the stepped piston of the pressure increasing mechanism is moved against the return spring, and the pressure increasing mechanism is immediately actuated and the hydraulic pressure in the master cylinder is increased. The pressure is increased and transmitted to the wheel cylinder. According to the second aspect of the invention, when the hydraulic booster or the hydraulic pressure source of the hydraulic booster fails, the hydraulic pressure of the third pressure chamber acting on the end surface of the valve member becomes zero. When the hydraulic pressure in the third pressure chamber becomes zero, the spring blocks the communication between the first communication passage and the second communication passage, and disconnects the communication state between the first pressure chamber and the second pressure chamber. Therefore, when the hydraulic pressure in the master cylinder increases and the hydraulic pressure in the first pressure chamber increases thereafter, the stepped piston of the pressure increasing mechanism is moved against the spring, and the pressure increasing mechanism immediately operates. Therefore, according to the present invention described above, it is possible to prevent an operation delay 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 the accumulator 12 and the pump 13 by a liquid passage 11,
The brake fluid stored in the reservoir 14 is fed to the accumulator 12 by the pump 13 and then 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. In this embodiment, the hydraulic pressure of the accumulator 12 also acts on the pressure increasing mechanism 7 via the brake fluid passage 16. Therefore, as shown in FIG. 2, the pressure increasing mechanism 7 includes a casing 21 having a stepped hole 21A formed therein, and a stepped piston 22 is held in the stepped hole 21A in a liquid-tight manner and slides. It fits freely. In this embodiment, the control valve 8 is incorporated in the stepped piston 22. End surface 22b of large diameter portion 22a of stepped piston 22 and casing 21 facing it
Of the stepped hole 21A 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 defines the axial hole of the casing 21 and the brake fluid connected thereto. It communicates with the master cylinder 3 via a passage 4. As a result, the brake fluid is introduced into the first pressure chamber 23, and the brake fluid pressure generated in the master cylinder 3 acts. The second pressure chamber 24 is defined by the end surface 22d of the small diameter portion 22c of the stepped piston 22, the wall surface of the casing 21 facing the stepped piston 22 and the inner portion of the small diameter hole 21b of the stepped hole 21A. 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 end surface 22e, and the large diameter hole 21.
A third pressure chamber 25 is defined by the inner part of a, and the third pressure chamber 25 communicates with the accumulator 12 via a radial passage 21c provided in the casing 21 and a brake fluid passage 16 connected thereto. are doing. Therefore, the hydraulic pressure of the accumulator 12 is introduced into the third pressure chamber 25. The stepped end surface of the stepped hole 21A and the stepped end surface 2 of the stepped piston 22 which are inside the third pressure chamber 25.
The return spring 26 is mounted over 2e, and the return spring 26 'is mounted over the small diameter portion 22c and the end surface of the small diameter hole 21b. Therefore, when the hydraulic pressure booster 2 and the accumulator 12 that is the hydraulic pressure source are normal, the stepped piston 22 biased by the return springs 26, 26 'has an end face 22b with a stepped hole 21a. Is stopped at a non-actuated position in the drawing where it abuts on the upper end surface of the. The shaft portion of the stepped piston 22 has a communication passage 2 formed of an axial through hole.
2f is provided, and the first pressure chamber 23 and the second pressure chamber 24 can be communicated with each other through the communication passage 22f. An annular valve seat 27 having a tapered surface facing upward is formed at a predetermined position of the communication passage 22f, and a spherical valve body 28 is arranged in the communication passage 22f located near and above the valve seat 27. I have set up. The communication passage 22f, which is located above the valve body 28, has a large diameter, and a substantially cup-shaped first pressing member 31 is slidably fitted in the diameter-increased portion. The first pressing member 31 is biased downward by a compression spring 32 having a predetermined set load. Therefore, the protrusion 31a at the center of the lower surface of the first pressing member 31 contacts the valve body 28 from above. Contact
The valve body 28 is pushed down in the direction in which it is seated on the valve seat 27 (downward). In addition, an axial through hole that allows the flow of the brake fluid is formed at a required position of the first pressing member 31. On the opposite side of the first pressing member 31 with the valve body 28 sandwiched therebetween, a stepped communication hole 22g having one end opening to the communication passage 22f and the other end communicating with the third pressure chamber 25 is formed. There is.
A second pressing member 33 having the same shape as the first pressing member 31 is slidably fitted in the communication hole 22g while maintaining liquid tightness, and the protruding portion 33a located on the upper side is connected. It is located in the passage 22f and faces the valve element 28.
On the other hand, the hydraulic pressure of the accumulator introduced into the third pressure chamber 25 acts on the end portion on the side opposite to the projecting portion 33a, and the second pressing member 33 is moved upward by the biasing force of the hydraulic pressure. Is urged towards. Further, the compression spring 3 in which the set load is set to be smaller than that of the compression spring 32 over the second pressing member 33 and the end surface of the communication hole 22g.
4 is mounted so that the second pressing member 33 is biased upward. Therefore, in a normal state in which the hydraulic pressure of the accumulator 12 is introduced into the third pressure chamber 25, the total urging force of the urging force of the hydraulic pressure in the third pressure chamber 25 and the urging force of the compression spring 34 is applied. The second pressing member 33 is pushed up toward the upper side. The urging force that pushes up the second pressing member 33 upward is larger than the urging force of the compression spring 32 that presses down the valve body 28 via the first pressing member 31.
The pressing member 33 is stopped at the non-operating position shown in the figure in which the step end surface of the pressing member 33 contacts the step end surface of the communication hole 22g. And
At this time, since the tip of the protruding portion 33a of the second pressing member 33 contacts the valve body 28 and pushes it up, the valve body 28 is separated from the valve seat 27, and therefore, via the communication passage 22f. The first pressure chamber 23 and the second pressure chamber 24 communicate with each other. In this embodiment, the communication passage 22f provided in the stepped piston 22 as described above, the valve seat 27, the valve body 28, and the both pressing members 3 are provided.
1, 33, the compression springs 32, 34 and the communication hole 22g constitute the control valve 8. In the above configuration, when the hydraulic booster 2 and the accumulator 12 and the pump 13, which are the hydraulic pressure sources thereof, are operating normally,
Since the hydraulic pressure of the accumulator 12 acts on the third pressure chamber 25, the second pressing member 33 is actuated by the urging force of the compression spring 34 and the urging force of the hydraulic pressure in the third pressure chamber 25 so that the second pressing member 33 is in the inoperative position. Is located in. Therefore, the valve body 28 is separated from the valve seat 27, and the valve body 28 is separated from the valve seat 27 via the communication passage 22f.
The pressure chamber 23 and the second pressure chamber 24 communicate with each other, and the master cylinder 3 and the front wheel cylinder 5 communicate with each other.
Further, the stepped piston 22 has return springs 26, 2
6'is in the inoperative position shown. 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
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 22 of the stepped piston 22.
f, transmitted to the front wheel cylinder 5 via the brake fluid passage 4 on the downstream side of the second pressure chamber 24 and the pressure increasing mechanism 7. As a result, normal braking operation can be obtained. Even if the brake pedal 1 is depressed after reaching the full load point where the boosting ratio of the hydraulic booster 2 becomes 1, the valve body 28 is separated from the valve seat 27, so that the master cylinder 3 is It communicates with the front wheel cylinder 5 via the brake fluid passage 4 and the pressure increasing mechanism 7. Therefore, tentatively, the stepped piston 22 will cause the return spring 2 to
Even if 6 and 26 'are compressed and displaced from the non-actuated position, the pressure increasing mechanism 7 is not actuated. Compared to the normal state, when the accumulator 12 and the pump 13, which are hydraulic pressure sources, malfunction and the boosting function of the hydraulic booster device 2 cannot be obtained, the hydraulic fluid of the accumulator 12 that acts on the third pressure chamber 25 is obtained. Pressure drops to zero or close to zero. Therefore, the third acting on the second pressing member 33
Since the hydraulic pressure in the pressure chamber 25 also decreases to zero or a level close to zero, the second pressing member 33 is biased upward only by the biasing force of the spring 34. At this time, the first pressing member 3
Since the urging force of the compression spring 32 that pushes the valve body 28 downward via 1 is greater than the urging force of the compression spring 34 that pushes up the valve body 28 via the second pressing member 33, the valve body 28 Is seated on the valve seat 27 and the communication passage 22f is closed. Therefore, the communication between the first pressure chamber 23 and the second pressure chamber 24 is blocked, and the 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 brake pedal 1
The pedaling force of is transmitted to the master cylinder 3 as it is. As a result, brake fluid pressure is generated in the master cylinder 3,
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 elastic force of the return springs 26, 26 ', and accordingly, the sectional area of the small diameter portion 22c relative to the sectional area of the large diameter portion 22a of the stepped piston 22 is reduced. Second according to the ratio of
The brake fluid pressure in the pressure chamber 24 is increased, and the increased brake fluid pressure is transmitted to the front wheel cylinder 5. As described above, in this embodiment, the accumulator that acts on the third pressure chamber 25 when the hydraulic pressure source of the hydraulic booster 2 fails and the boosting function of the hydraulic booster 2 cannot be obtained. The hydraulic pressure of 12 decreases, and the difference between the set loads of the compression spring 32 and the compression spring 34 causes the valve body 28 to move to the valve seat 27.
The master cylinder 3 and the front wheel cylinder 5 are prevented from communicating with each other. Then, when the brake pedal 1 is subsequently depressed, the pressure increasing mechanism 7 is immediately activated. Therefore, it is possible to prevent the operation delay of the pressure increasing mechanism 7 from occurring when the hydraulic booster 2 fails. Further, as described above, even if the hydraulic booster 2 reaches the full load point in the normal state, the pressure boosting mechanism 7 is not operated, so that the pressure boosting action by the pressure boosting mechanism 7 cannot be obtained. Therefore, in the present embodiment, it is not necessary to provide the brake fluid passage 16 with a limiter for preventing the boosting action of the booster mechanism 7 from being obtained after the hydraulic booster 2 reaches the full load point. (Second Embodiment) Next, FIG. 3 shows a second embodiment of the present invention. In the second embodiment, both pressing members 31, 33 in the first embodiment are arranged upside down.
That is, in the second embodiment, the valve seat 127 is formed from the taper surface facing downward, and the valve body 128 is arranged at the lower position in the vicinity of the valve seat 127. Then, the valve body 128 is biased upward by the first pressing member 131 and the compression spring 132 similar to those in the first embodiment, while the valve is pressed by the second pressing member 133 and the compression spring 134 similar to those in the first embodiment. The body 128 is pushed downward. Further, the liquid pressure in the third pressure chamber 125 is applied to the second pressing member 133. In the second embodiment, the return spring 2 provided in the second pressure chamber 24 of the first embodiment is used.
6'is omitted and a single return spring 126
The stepped piston 122 is located at the non-actuated position in the figure. Other configurations are the same as those in the first embodiment, and each member corresponding to the first embodiment has a member number added with 100. The second of such a configuration
In the embodiment, the hydraulic pressure of the accumulator 112 is the third pressure chamber 125 when the hydraulic booster and the accumulator 112, which is the hydraulic pressure source, are operating normally.
Therefore, the valve element 128 is separated from the valve seat 127, and the master cylinder 103 and the wheel cylinder 105 communicate with each other. Further, the stepped piston 122 is positioned at the inoperative position in the drawing by the return spring 126. 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 increased. The front wheel cylinder 105 is not pressurized by the mechanism 107.
Is transmitted to As a result, normal braking operation can be obtained. Even if the brake pedal is depressed after reaching the full load point at which the boosting ratio of the hydraulic booster becomes 1, the valve body 128 is separated from the valve seat 127, so that the stepped piston is temporarily operated. 122 is the return spring 12
Even if 6 is compressed and slid in the stepped hole 121A, the pressure increasing mechanism 107 is not operated. Compared to the normal state, 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, the hydraulic pressure of the accumulator 112 acting on the third pressure chamber 125 becomes zero. Or it decreases to a level close to it. Therefore, the hydraulic pressure acting on the second pressing member 133 becomes zero, and the second pressing member 133 is biased downward only by the biasing force of the compression spring 134. At this time,
The compression spring 13 that biases the first pressing member 131 upward.
Since the urging force of No. 4 is larger than the urging force of the compression spring 134, the valve body 128 is seated on the valve seat 127 and the communication passage 12
2f is closed. As a result, the communication between the first pressure chamber 123 and the second pressure chamber 124 is blocked, and the communication between the master cylinder 103 and the front wheel cylinder 105 is blocked. When the brake pedal is depressed from this state, the master cylinder 10 is activated as in the first embodiment described above.
The brake fluid pressure of No. 3 is increased by the pressure increasing mechanism 107 and transmitted to the front wheel cylinder 105. 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 this third embodiment, the stepped piston 222
A stepped communication hole 222g penetrating from one end surface 222b to the other end surface 222d is formed in the shaft part of
The communication hole 222g is connected to the third pressure chamber 2 through the radial hole.
It is connected to 25. A stepped columnar valve member 228 is slidably fitted in the communication hole 222g while maintaining liquid tightness. A plug 241 is fitted from the lower side to the large diameter portion that is the lower end of the communication hole 222g that is the lower side in the drawing. Then, the plug 2 located in the communication hole 222g
A compression spring 234 having a predetermined set load is mounted between one end surface of the valve 41 and the end surface of the valve member 228. The inside of the communication hole 222g in which the compression spring 234 is mounted is in communication with the third pressure chamber 225, and when the hydraulic pressure of the accumulator 212 is introduced into the third pressure chamber 225, the lower side of the valve member 228 is normal. The liquid pressure in the accumulator 212 acts on the end surface of the valve member 228 to urge the valve member 228 upward. On the other hand, the hydraulic pressure in the first pressure chamber 223 acts on the end surface of the small diameter portion on the upper side of the valve member 228 to urge the valve member 228 downward. And
When the hydraulic pressure of the accumulator 212 is operating normally in the third pressure chamber 225, the biasing force of the compression spring 234 is larger than the biasing force of the hydraulic pressure in the first pressure chamber 223 that biases the valve member 228 downward. Since the total urging force of the hydraulic pressure in the third pressure chamber 225 that pushes up the valve member 228 is larger, the step end surface of the valve member 228 is closer to the step end surface of the communication hole 222g. It is stopped at the non-actuated position shown in the drawing. A first communication passage 228a is formed in a small diameter portion on the upper side of the valve member 228, and one end of the first communication passage 228a is opened to an end face on the upper side and communicates with the first pressure chamber 223. And the other end is open at a predetermined axial position on the outer peripheral surface. On the other hand, the stepped piston 222 has a second
A communication passage 222j is provided, and the second communication passage 222j is provided.
One end of the second communication passage 222j opens to the third pressure chamber 224, and the other end of the second communication passage 222j opens to a predetermined axial position on the inner peripheral surface of the communication hole 222f. Then, when the valve member 228 described above is in the inoperative position, the second communication passage 2
22j one end opening and the valve member 228 side first communication passage 228
The one end of a is polymerized, and these communication passages 222j, 22
Since the 7a communicate with each other, the first pressure chamber 223 and the second pressure chamber 224 communicate with each other through them. In the embodiment of FIG. 4, the space formed between the step end surface of the valve member 228 and the step end surface of the communication hole 222f is defined as the hole 222k of the stepped piston 222 and the hole 221e of the casing 221. It is connected to the atmosphere or the reservoir via. Further, in this third embodiment, the return spring 226 is elastically mounted over the end surface of the plug 241 in the second pressure chamber 224 and the end surface on the lower side of the stepped hole 221a. Other configurations are similar to those of the first embodiment, and each member corresponding to the first embodiment has 20
The member number with 0 added is attached. In the third embodiment having the above-described configuration, in a normal state, the hydraulic pressure of the accumulator 212 acts on the third pressure chamber 225 and also acts on the lower end surface of the valve member 228. 228 is located in the inoperative position shown. for that reason,
The first communication passage 228a and the second communication passage 222j communicate with each other, and the first pressure chamber 223 and the second pressure chamber 2 are connected via them.
24 is in communication, and the stepped piston 222 is also biased by the return spring 226 and is in the inoperative position in the drawing. Even if the brake pedal is depressed from this state,
The pressure boosting mechanism 207 is never activated. On the other hand, the hydraulic pressure source of the brake booster fails and the third pressure chamber 22
When the hydraulic pressure in 5 becomes zero, the hydraulic pressure in the third pressure chamber 225 acting on the lower end surface of the valve member 228 also becomes zero,
The valve member 228 is biased upward only by the biasing force of the compression spring 234. From this state, the brake pedal is depressed to increase the hydraulic pressure in the master cylinder 203 and
When acting on the pressure chamber 223, the hydraulic pressure of the first pressure chamber 223 also acts on the upper end surface of the valve member 228. Since the urging force that acts on the upper end surface of the valve member 228 to push down the valve member 228 is larger than the urging force that the compression spring 234 urges the valve member 228 upward, the valve member 228 is stepped. The piston 222 is pushed down. Therefore, the communication between the two communication passages 228a and 222j is blocked, and the communication between the first pressure chamber 223 and the second pressure chamber 224 is also blocked. Therefore, the stepped piston 222 is pushed downward against the return spring 226 by the hydraulic pressure of the master cylinder 203 acting on the first pressure chamber 223, and the brake fluid in the second pressure chamber 224 is increased in pressure, The increased brake fluid pressure is applied to the wheel cylinder 2
It is transmitted to 05. The third embodiment having such a configuration can also obtain the same effects as those of the above-described embodiments. (Fourth Embodiment) FIG. 5 shows a fourth embodiment of the present invention. In the fourth embodiment, the arrangement position of the compression spring 234 that axially biases the valve member 228 in the third embodiment is changed. That is, in the fourth embodiment, the compression spring 334 is elastically mounted on the step end surface of the valve member 328 and the step end surface of the communication hole 322g to urge the valve member 328 downward. When the hydraulic pressure of the accumulator 312 normally acts on the lower end surface of the valve member 328, the compression spring 334 is compressed by the hydraulic pressure of the accumulator 312 that biases the valve member 328 upward, and the valve member 328 is compressed. Is pushed up and descends, and the stepped end face of the valve member 228 is located at a non-operation position shown in the drawing in which the stepped end face abuts on an annular stopper portion 322h formed in the communication hole 322g. The other structure is the same as that of the third embodiment shown in FIG. 4, and each member corresponding to the third embodiment has a member number added with 100. In the fourth embodiment having the above configuration, the accumulator 3
During normal operation when the hydraulic pressure of 12 acts on the third pressure chamber 325, the valve member 328 is in the inoperative position in the drawing, so that both communication passages 328a and 322j communicate with each other and the first pressure chamber 32
3 and the second pressure chamber 324 communicate with each other. Therefore,
Even if the brake pedal is depressed from this state, the control valve 3
08 and the pressure increasing mechanism 307 are not activated. On the other hand, when the hydraulic pressure in the accumulator 312 becomes zero, the third pressure chamber 32 acting on the lower end surface of the valve member 328 is stopped.
The hydraulic pressure of 5 also becomes zero. Therefore, the urging force of the compression spring 334 causes the valve member 328 to be pushed downward with respect to the stepped piston 322, whereby
The communication between both communication passages 328a and 322j is blocked. Therefore, the communication between the first pressure chamber 323 and the second pressure chamber 324 is also blocked. When the brake pedal is depressed from this state and the brake fluid pressure in the master cylinder 303 rises,
Since the brake fluid pressure acts on the first pressure chamber 323,
The stepped piston 322 is pushed downward against the return spring 326 to operate the pressure increasing mechanism 307.
Even in the fourth embodiment having such a configuration, it is possible to obtain the same effects as those of the above-described embodiments. In addition, the first to the first
In the fourth embodiment, the third pressure chambers 25, 125, 225, 32
Although the hydraulic pressure of the accumulator is applied to 5, the hydraulic pressure of the power chamber of the hydraulic booster 2 may be applied. In this case as well, the same effect can be obtained.

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.

FIG. 5 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 21 ... casing 22 ... stepped piston 23 ... first pressure chamber 24 ... second pressure chamber 25 ... third pressure chamber 26 ... return spring 27 ... valve seat 28 ... valve element 31 ... first pressing member 32 ... compression spring (first
33) second pressing member 34 ... compression spring (second)
Spring)

Claims (2)

[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. And a control valve for activating the pressure boosting mechanism when the hydraulic booster fails, and the pressure boosting mechanism is provided with a stepped penetrating hole formed in the casing. A stepped piston that is slidably fitted in a hole while maintaining liquid tightness, and a first pressure that is formed on the large diameter side of the stepped piston in the casing and communicates with the master cylinder. A second pressure chamber formed on the small diameter side of the stepped piston in the casing and communicating with the wheel cylinder; and a second pressure chamber formed at a position facing the stepped end surface of the stepped piston in the casing, It comprises a third pressure chamber that communicates with the power chamber of the booster or the hydraulic pressure source of the hydraulic booster, and a return spring that returns the stepped piston to the inoperative position, and increases the pressure of the control valve. In the braking device provided on the stepped piston of the mechanism, the control valve is formed on the stepped piston, and
A communication passage that communicates the pressure chamber and the second pressure chamber, an annular valve seat formed at a predetermined position of the communication passage, and a communication passage that is movably provided in the communication passage and comes in contact with and separates from the valve seat. A valve body that opens and closes the valve body, is engaged in the valve body while being disposed in the communication passage, and urges the valve body in a direction to be seated on the valve seat by a first spring having a predetermined set load. The first pressing member is slidably provided at a predetermined position of the stepped piston on the opposite side of the first pressing member with the valve element interposed therebetween, and one end of the stepping piston engages with the valve element from the opposite side of the first pressing member. And a second pressing member for urging the valve body in the direction of separating from the valve seat by the hydraulic pressure of the third pressure chamber applied to the other end, and a predetermined set load, and the second pressing member. And a second spring for urging the valve body in a direction of separating from the valve seat via a member. 2. A master cylinder for exerting brake fluid pressure on a wheel cylinder, and a brake pedal, which is provided between the brake pedal and the master cylinder and has a predetermined ratio of the pedal effort of the brake pedal when the brake pedal is depressed. 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. And a control valve for activating the pressure boosting mechanism when the hydraulic booster fails, and the pressure boosting mechanism is provided with a stepped penetrating hole formed in the casing. A stepped piston that is slidably fitted in a hole while maintaining liquid tightness, and a first pressure that is formed on the large diameter side of the stepped piston in the casing and communicates with the master cylinder. A second pressure chamber formed on the small diameter side of the stepped piston in the casing and communicating with the wheel cylinder; and a second pressure chamber formed at a position facing the stepped end surface of the stepped piston in the casing, The control valve is composed of a third pressure chamber communicating with a power chamber of the booster or a hydraulic pressure source of the hydraulic booster, and a return spring for returning the stepped piston to a non-actuated position. In the brake device provided in the stepped piston, the control valve is provided with a stepped communication hole that is bored in the stepped piston and that connects the first pressure chamber and the third pressure chamber to each other, and a liquid is provided in the communication hole. A stepped valve member that is slidably fitted while maintaining a tightness and has one end surface acted on by the hydraulic pressure of the first pressure chamber and the other end surface acted on by the hydraulic pressure of the third pressure chamber. And the one end formed on the valve member is the first A first communication passage communicating with the force chamber and having the other end opened at a predetermined axial position on the outer peripheral surface and the stepped piston, and one end opened at a predetermined axial position on the inner peripheral surface of the communication hole. And a second communication passage communicating with the communication hole and having the other end communicating with the second pressure chamber, and the valve member is axially biased, and the valve member is acted upon by the hydraulic pressure of the third pressure chamber. When the hydraulic pressure of the third pressure chamber is not acting on the valve member, the first communicating passage and the second communicating passage are communicated with each other, and the valve member is axially moved in the communicating hole to move the first communicating passage. And a spring that blocks communication between the second communication passage and the second communication passage.