JPH04224458A - Brake liquid pressure control device - Google Patents

Abstract

PURPOSE:To ensure the safety when an aux. power source and its system are failed, by enhancing the effect of brake application through improvement of the structure of a pressurizing unit. CONSTITUTION:A braking liquid pressure control device as per invention comprises a master cylinder 1, aux. power source 3, and pressurizing unit 2, and this unit is equipped with a first piston 32, second piston 33, and fast-fill piston 37. First a feedback port 42 is shut through utilization of the boost pressure, and then the second piston 33 is moved left, and the front wheel brake 4 is actuated with the pressure of a third cylinder chamber. In the initial period of braking, the pressure oil is supplied without putting the master cylinder 1 in strokes, and in the middle period of controlling the effect of brake is increased because of being assisted by the boost pressure. When the aux. system is in failure, the master cylinder pressure is applied to the second cylinder chamber 35 to shut feedback port, and the pressure oil in the third cylinder chamber 3b is supplied to the front wheel brake 4.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake fluid pressure control device, and more particularly, it is equipped with a fluid pressure booster that utilizes auxiliary power pressure from an auxiliary power source, and uses the boost pressure to pressurize, for example, some wheel brakes. In a brake fluid pressure control device that pressurizes other wheel brakes using the master cylinder's fluid pressure, especially when a failure occurs in the auxiliary power source or the boost pressure introduction line and the boost pressure decreases, This ensures sufficient brake effectiveness and reduces the feeling of play by improving the relationship between the brake pedal stroke and brake effectiveness at the initial stage of braking under normal conditions.

0002

[Prior Art] Conventionally, in an automobile brake system, an auxiliary power source is provided which draws and pressurizes hydraulic fluid stored in a reservoir with a pump and stores it as a constantly high auxiliary power pressure, and this auxiliary power pressure is utilized. It is known to provide hydraulic boosters and to use them in place of conventional vacuum boosters. This hydraulic booster can be easily miniaturized and increased in magnification, and can be integrated with a master cylinder and an anti-lock control device to improve installation on a vehicle.

In addition, the boost pressure of the hydraulic booster assists the thrust of the master cylinder due to pedal force, and for some wheel brakes, instead of pressurizing with static fluid from the conventional master cylinder, this fluid is used to pressurize some wheel brakes. A method is known in which pressurization is performed using a dynamic fluid having boost pressure generated in a boost chamber of a pressure booster.

For example, in the pressure control mechanism for the brake actuating cylinder disclosed in Japanese Patent Application Laid-Open No. 57-104449, the master cylinder pressurizes the front wheel brake, the boost pressure pressurizes the rear wheel brake, and the boost chamber and By providing an introduction valve that opens and closes communication with the rear wheel brake and a discharge valve that discharges dynamic fluid from the rear wheel brake to a reservoir, a dynamic fluid anti-lock device is configured on the rear wheel side. In this way, unlike the static fluid side, there is no problem of stroke consumption of the master cylinder, so it is possible to construct an anti-lock device for the rear wheels extremely easily.

However, in the above-mentioned pressure control mechanism, when a failure occurs in the auxiliary power source or the rear wheel brake circuit, the rear wheel brake cannot be pressurized and the boost function of the booster is also lost. When the boost function is lost, the pedal effort required to obtain a certain level of braking effectiveness increases. In other words, a problem arises in that even if the brake pedal is depressed with a certain level of force, the braking effectiveness is small.

Under such conditions, in order to keep the pedal force necessary to obtain a constant brake effectiveness to a sufficiently low level, it is necessary to reduce the diameter of the master cylinder. However, in that case, there is a problem in that the pedal stroke during normal operation becomes large and the rigidity of the brake deteriorates.

In order to solve the above problem, the present applicant previously proposed in Japanese Patent Application No. 2-186328 that a failure occurred in the brake circuit from the auxiliary power source or the boost chamber to the wheel brakes, and the boost pressure was normal. The master cylinder diameter is set small enough to reduce the pedal force required to obtain a certain level of braking effectiveness even if the brake stops rising. The present invention provides a brake fluid pressure control device that is configured to operate the brake with a sufficiently short pedal stroke in normal conditions, and ensures a feeling of rigidity of the brake in normal conditions.

[0008]

[Problem to be Solved by the Invention] The above-mentioned device is shown in FIG.
As shown in , during normal operation, port 1 of the pressurizing unit 100
The valve body 1 moves integrally with the second piston 103 of the large diameter by pushing the second piston 103 of the large diameter with the first piston 102 of the small diameter due to the boost pressure increase introduced from 01.
A seal member 105 provided at the tip of 04 closes the port 106 communicating with the reservoir, and at the same time closes the port 107.
The master cylinder pressure introduced from the second piston 10
3 to supply pressure fluid in the cylinder chamber 108 to port 1.
10 to the front wheel brake 111.

The relationship between the stroke of the brake pedal and the effectiveness of the brake in this type of brake device is as shown in FIG. Even when the brakes start to work, the brake pressure gradually increases, so there is a large sense of play, or in other words, the brakes have a disadvantage that the effectiveness of the brakes lags behind the driver's intention. On the other hand, in the apparatus of the present applicant, as shown by the dashed line B in the figure,
Since the brake pressure is increased more rapidly than in conventional general devices, the feeling of play can be reduced.

However, even in the device according to the invention of the present applicant, after the boost pressure increases and the first piston moves the second piston, the second piston goes through a stroke S1 in which the brake effect is zero. When moving to close the return port to the reservoir and supply pressure fluid to the wheel brakes together with the master cylinder pressure, the pressure fluid supplied to the wheel brakes is gradually pressurized so that
Although this is an improvement over conventional brake devices, there is a problem in that a slight sense of play remains when the brakes begin to work, that is, at the initial stage of braking.

The present invention improves the above-mentioned brake device related to the present applicant, and as shown by the solid line C in the above-mentioned FIG. The purpose is to eliminate the sense of play by making the game more accessible.

0012

[Means for Solving the Problems] In order to achieve the above object, the present invention provides the above-mentioned apparatus related to the present applicant, which includes:
A fast fill piston that slidably passes through the second piston, has one end moved in contact with the first piston that is moved by boost pressure, and has a valve body provided at the other end to open and close a return port to the reservoir. is attached, and as the first piston moves, the fast-fill piston is first moved to close the recirculation port, and the first By adopting a configuration in which the volume of the second cylinder chamber to which master cylinder pressure is supplied between the piston and the second piston does not change, the master cylinder stroke at the initial stage of braking, that is, the pedal stroke, is reduced, and the effectiveness of the brake relative to the pedal stroke is reduced. This improves the sense of play and eliminates the sense of play.

Specifically, the present invention includes a master cylinder that is driven by a pedal force applied to a brake pedal and generates brake fluid pressure, an auxiliary power source that sucks and pressurizes fluid from a reservoir and constantly stores it as auxiliary power pressure, and a boost cylinder that generates brake fluid pressure. When the brake pedal is operated, it receives auxiliary power pressure from the auxiliary power source to generate boost pressure in the boost chamber proportional to the pedal force, and this boost pressure assists the thrust of the master cylinder due to the pedal force. In addition, in a brake hydraulic pressure control device having a hydraulic pressure booster configured to use boost pressure as brake pressure, the housing includes a large diameter hole and a small diameter hole in series, and a housing that is slidable in the small diameter hole. a first piston that is movably fitted to vary the volume of the first cylinder chamber in the small diameter hole; and a first piston that is slidably fitted to the large diameter hole to connect the large diameter hole to a second cylinder chamber; a second piston that separates the liquid seal into three cylinder chambers;
A fast-fill piston that penetrates the second piston in a liquid-tight and slidable manner and has a collar portion extending toward the end surface of the second piston at the tip on the third cylinder chamber side; means for urging the second cylinder chamber toward the second cylinder chamber; a port connecting the first cylinder chamber to a passage communicating with the boost chamber; a port connecting the second cylinder chamber to the passage communicating with the master cylinder; a port that connects the cylinder chamber to a passage communicating with one or more wheel brakes; a port that communicates the third cylinder chamber with an open passage that communicates with the reservoir; and a port that communicates the open passage and the third cylinder chamber. A pressurizing unit is provided in which an opening/closing means is connected to the fast fill piston, and when the boost pressure is normal, the fast fill piston is moved by the first piston receiving the boost pressure to close the opening/closing means,
After the valve is closed, the fluid in the third cylinder chamber is supplied to the wheel brake only by the fast-fill piston until a certain stroke, and the fluid is pressurized. After that, the first piston pushes the second piston, and the second piston is given boost pressure. The master cylinder pressure moves to the third cylinder chamber side, and the pressure fluid in the third cylinder chamber is supplied to the wheel brakes and pressurized. However, when boost pressure fails, only the master cylinder fluid pressure is applied to all the second and fast fill pistons. The present invention provides a brake fluid pressure control device characterized in that the second piston and the fast fill piston are moved by acting on the area, and the opening/closing means is closed to pressurize the wheel brake.

In the above device, the diameter of the fast-fill piston and the diameter of the first piston are set to be the same, and after the first piston moves the fast-fill piston and the reflux port is closed by the opening/closing means, the diameter of the fast-fill piston and the second piston are set to be the same. Until they come into contact, the volume of the second cylinder chamber into which the master cylinder pressure between the second piston and the first piston is introduced is maintained constant.

[0015] Furthermore, the present invention provides a first
A pressure regulating means consisting of a switching valve is provided in the middle of a passage communicating between the cylinder chamber and the boost chamber, and the first cylinder chamber is selectively communicated with the boost chamber and the reservoir, and the passage is closed. is closed, thereby making it possible to adjust the hydraulic pressure in the first cylinder chamber.Furthermore, passage opening/closing means provided in the middle of a passage communicating the master cylinder and the second cylinder chamber, and both ends of the second piston are provided. an intermediate chamber that is liquid-sealed, a passage that communicates the intermediate chamber with the master cylinder, and a passage that communicates the intermediate chamber provided inside the second piston and/or the fast fill piston with the second cylinder chamber; The present invention provides a brake fluid pressure control device that is provided with means for opening and closing communication between the intermediate chamber and the second cylinder chamber, and is capable of performing an anti-lock operation.

Furthermore, in the present invention, a switching valve is provided upstream of the pressure regulating means to selectively communicate the boost chamber and the auxiliary power source to the first cylinder chamber, and the auxiliary power source is directly connected to the first cylinder chamber. This allows traction control operation to be performed by introducing pressure.

[0017]

[Operation] In the present invention, by having the above configuration,
Under normal conditions, in order to perform the necessary braking according to the pedal force,
Part of the volume of fluid that needs to be supplied to the wheel brakes is indirectly supplied from the boost chamber via the pressurizing unit to the wheel brake side, which is pressurized by the master cylinder pressure. Even if the cylinder diameter is set small, the rigidity of the brake can be maintained.

In particular, this device is equipped with a fast-fill piston, and the first piston on which boost pressure acts moves directly to close the reflux port without going through the second piston, thereby increasing the pressure at the initial stage of braking. conduct. During this time, the volume of the second cylinder chamber on which the master cylinder pressure acts is kept constant, so the master cylinder does not need to stroke, and the pedal stroke at the beginning of braking, which required a large value in conventional brake systems, is shortened, giving a sense of play. can be eliminated.

Furthermore, as mentioned above, since the diameter of the master cylinder can be reduced while ensuring the rigidity of the brake and eliminating the feeling of play in the brake, defects in the other wheel brake circuit can be detected from the supply power source or boost chamber. Even in the event that pressurization on the wheel brake side and master cylinder thrust assistance become impossible, the wheel brake on the side to be pressurized on the master cylinder side can be maintained with sufficient braking force with the required small pedal force. It can be secured.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail below with reference to embodiments shown in the drawings. 1 and 2 show a first embodiment, in which 1 is a braking unit, 2 is a pressurizing unit, 3 is an auxiliary power source, and 4 is a braking unit.
5 is a front wheel brake, 5 is a rear wheel brake, and the pressurizing unit 2 is provided to supply the front wheel brake 4 with a volume of fluid necessary to shorten the stroke of the master cylinder 6 in the braking unit 1. .

The braking unit 1 shown in FIG. 2 has a known structure in which the master cylinder 6 and a hydraulic booster 7 (hereinafter referred to as booster 7) are incorporated, and the booster 7 is connected to an auxiliary power source 3. High pressure auxiliary power pressure is supplied via passage 9. The auxiliary power source 2 includes a motor 10, a pump 11 and an accumulator 12,
The hydraulic fluid is suctioned and pressurized from the reservoir 13 through the passage 14, and a constantly high auxiliary power pressure is stored in the accumulator 12.

The booster 7 has a boost chamber 15,
The auxiliary power pressure supplied from the auxiliary power source 3 to the port 17 of the braking unit 1 is supplied when the brake pedal 16 is operated, and introduced into the boost chamber 15 via the flow paths 18A to 18D,
A boost pressure proportional to the depression force of the brake pedal 16 is generated in the boost chamber 15, and the boost pressure presses the boost piston 25 to assist the thrust of the master cylinder 6 due to the depression force.

The boost chamber 15 is communicated with the rear brake 5 from the port 19 through a passage 20, and at the same time the rear brake 5 is pressurized by the boost pressure, and at the same time, the boost chamber 15 is connected to the pressurizing unit through a passage 26 branched from the passage 20. 2, and as will be described later, the hydraulic pressure applied to the front wheel brake 4 is increased by boost pressure in the pressurizing unit 2.

On the other hand, the master cylinder pressure generated in the master cylinder chamber 21 in the braking unit 1 is introduced to the front wheel brake 4 via the passage 22, the pressurizing unit 2, and the passage 23, so that the master cylinder pressure is transferred to the pressurizing unit. After pressurizing with boost pressure in step 2, the boost pressure is introduced into the front wheel brake 4, and the front wheel brake 4 is pressurized.

The pressure unit 2 has a stepped hole 31 in the axial direction in the housing 30, and the stepped hole 31 has a small diameter hole 31a with a diameter (a) on the right end side in the figure and a diameter (a) in the middle part. b
), a large diameter hole 31c (diameter (c)) is continuously provided in series on the left end side, and the small diameter hole 31 is
It has a shape in which an annular protrusion 31d is provided between the hole 31a and the minimum diameter hole 31b.

A first piston 32 is provided in the small diameter hole 31a.
are fitted in a fluid-sealed and slidable manner, and the annular protrusion 31d is penetrated in a fluid-sealed and slidable manner to form the minimum diameter hole 31.
b, and a small-diameter first hole having a diameter (a) between one end surface 32a of the first piston 32 and the end surface of the small-diameter hole 31a.
A cylinder chamber 34 is formed.

[0027] Also, the second piston 3 is installed in the large diameter hole 31c.
3 is fluid-sealed and slidably fitted, and between the right end surface of the second piston 33 in the figure and the annular protrusion 31d closed by the first piston 32, there is a hole between the minimum hole 31b and the large diameter. While forming a second cylinder chamber 35 that communicates with the hole 31c, the left end surface in the figure of the second piston 33 and the large diameter hole 31c
A large-diameter third cylinder chamber 36 with a diameter (c) between the end face of
is formed.

A fast-fill piston 37 is attached to the second piston 33 at its axial center in a liquid-sealed and slidable manner. The fast fill piston 37 has the same diameter (d) as the diameter (d) of the first piston 32, and has an end surface protruding toward the third cylinder chamber 36 that is slidable on the inner wall of the third cylinder chamber 36. The fast-fill piston has a collar portion 37a that abuts, and a spring 39 is tensioned between the collar portion 37a and an opening/closing valve means cover member 38, which will be described later, installed on the end face side of the large diameter hole portion 31c. 37 toward the second cylinder chamber 35 side.

Therefore, as shown in FIG. 1, the collar 37a of the fast fill piston 37
The other end surface 33b of the second piston 33 is urged toward the second cylinder chamber 35 by contacting the end surface 33a of the second piston 33.
is brought into contact with a step portion 31f that defines the boundary between the large diameter hole portion 31c and the minimum diameter hole portion 31b. Further, the other end surface 37b of the fast fill piston 37 protruding into the second cylinder chamber 35 is in contact with the end surface of the first piston 32.

As shown in the figure, the fast fill piston 37 is provided with a groove 37c for moving the valve body, which is cut out along the axis from the distal end surface where the collar portion 37a is provided.
7c is a locking portion 40a at one end of the valve body 40 for opening and closing the reflux port.
are slidably engaged.

An on-off valve portion 41 made of a sealing member is attached to the other end of the valve body 40, and a return port 42 formed in the end face of the large diameter hole 31c is opened and closed in accordance with the movement of the valve body 40. I try to do that. The reflux port 42 is connected to the passage 4.
It communicates with the reservoir 13 via 4. Further, the opening/closing means cover member 38 is installed to be slidable on the valve body 40 so as to surround the opening/closing valve part 41, and a spring 43 is stretched between the cover member 38 and the opening/closing valve part 41, so that the valve body The body 40 is biased in the valve closing direction (to the left in the figure), so that the locking portion 40a on the other end side is always in contact with the collar portion 37a.

Small diameter hole 31a of the first cylinder chamber 34
A port 45 for introducing boost pressure is opened in the end face of the cylinder 3, and the port 45 is communicated with the passage 26, and the first cylinder chamber 3
Boost pressure is introduced into the piston 4 and acts on the first piston 32. Further, a port 46 for introducing master cylinder pressure is opened on the circumferential surface of the minimum diameter hole portion 31b, and the port 46 is communicated with the passage 22 to introduce master cylinder pressure into the second cylinder chamber 35. There is.

Further, a port 4 is provided on the circumferential surface of the large diameter hole 31c.
7 is opened, and the third cylinder chamber 36 is communicated with the front wheel brake 4 via the passage 23 as described above, and the fast fill piston is moved toward the third cylinder chamber by the thrust of the first piston, and When the second piston 33 moves toward the third cylinder chamber 36 due to the pressure in the second cylinder chamber 35, pressure fluid is supplied to the front wheel brake 4 through the passage 23.
has been introduced.

In the first embodiment having the above-described structure, if no failure occurs in the auxiliary power source 3 or the rear wheel brake circuit and the boost pressure increases normally by operating the brake pedal 16, , the boost pressure fluid passes from the boost chamber 15 through the passage 20 and pressurizes the rear wheel brake 5, and at the same time pressurizes the rear wheel brake 5 from the passage 26 to the first part of the pressurizing unit 2.
It flows into the cylinder chamber 34.

Therefore, from the state shown in FIG.
The fast-fill piston 37 is moved toward the third cylinder chamber 36 by being pressed by the piston 32, and the valve body 40 that is engaged with the fast-fill piston 37 also moves toward the third cylinder chamber 3.
6 side, and close the reflux port 42 with the opening/closing valve part 41 at the tip thereof.

As described above, even if the fast fill piston 37 is moved by the first piston 32, until the first piston 32 comes into contact with the second piston 33, the distance L in the figure is Until the first piston moves, the second
Piston 33 is in a stationary state. Moreover, since the diameter of the fast fill piston 37 and the diameter of the first piston 32 are set to be the same (d), the volume of the second cylinder chamber 35 does not change. Therefore, as shown in FIG. 6, the stroke S1 from when the pedal is depressed until the boost pressure increases
After the pressure is reached, the pedal does not stroke until a certain constant pressure is reached.

When the first piston 32 contacts the second piston 33, the second piston 33 is pressurized by the boost pressure acting on the first piston and the master cylinder pressure introduced into the second cylinder chamber 35. Move it to the cylinder chamber 36 side. In the third cylinder chamber 36, the recirculation port 42 is already closed by the on-off valve section 41, so the movement of the second piston 33 causes the pressurized fluid in the third cylinder chamber 36 to flow through the passage 23 to the front brake 4. be introduced.

In this way, the pressure fluid necessary to pressurize the front wheel brake can be supplied without stroking the master cylinder in the early stages of braking, and a certain proportion of the pressure fluid can be supplied to the first piston in the middle stage of braking. Since the boost pressure is supplied through the brake pedal, even if the diameter of the master cylinder is reduced, a brake system with a rigid feel can be constructed with a short pedal stroke.

Furthermore, due to the pressurizing operation using the boost pressure in the pressurizing unit 2, the relationship between the amount of fluid supplied by the master cylinder 6 and the amount of fluid required by the front wheel brake 4 is as shown in the following equation.

[0040]

【formula】

Master cylinder fluid volume = [Front brake fluid volume - (π
d2/4)・(L-S)]×(c2-d2)/c2

In the above formula, c is the third cylinder chamber 36
, d is the diameter of the fast-fill piston, L is the first
The distance S between the piston 32 and the second piston 33 is the distance between the return port 42 and the on-off valve section 41. As is clear from the above equation, the pressure fluid supplied from the master cylinder 6 to the front brake 4 side can be reduced. Since fluid is supplied from 2, it is possible to create a brake system that feels rigid with a short pedal stroke.

On the other hand, if a failure occurs in the auxiliary power source 3, the system related to the boost chamber 15, or the passage 20 to the rear wheel brake 5, the pressure in the boost chamber 15 will not increase, and therefore the pressurizing unit Since boost pressure is not introduced into the first cylinder chamber 34 of No. 2, the first piston 32 remains at the original position shown in FIG. In this case, the master cylinder chamber 21 of the braking unit 1 is directly pressurized manually without the aid of boost pressure. The pressure fluid generated in the master cylinder chamber 21 flows into the second cylinder chamber 35 through the passage 22 and the suction port 46 as in the normal state. At this time, since the second piston 33 separates from the first piston 32, pressure acts on the entire area of the second piston 33 and the fast fill piston 37, pressing them toward the third cylinder chamber 36. Therefore, the second piston 33 and the fast fill piston 37 move together to close the reflux port 42 and close the port 47.
, supplies pressure fluid to the front wheel brake 4 via the passage 23.

At this time, as mentioned above, the diameter of the master cylinder 6 is set to a size that can sufficiently reduce the pedal force required to obtain a certain level of braking effectiveness, so sufficient braking effectiveness is generated. I can do it. However, since the amount of fluid supplied by the master cylinder 6 is the same as the amount of fluid required by the wheel brakes 4, the pedal stroke will be larger than normal.

The present invention is not limited to the above-mentioned embodiment, but can also be constructed as shown in the second embodiment shown in FIG. 3 and the third embodiment shown in FIG. 4. Incidentally, in the second and third embodiments, the same members and portions as in the first embodiment are designated by the same reference numerals, and explanations thereof will be omitted.

The second embodiment shown in FIG. 3 allows anti-lock operation to be performed when the auxiliary power pressure is normal. In the second embodiment, a switching valve 60 is operated by auxiliary power pressure, and switching valves 61 and 6 are operated by an electric signal.
2 and 63 are provided, and the structures of the fast fill piston 70 and the second piston 65 of the pressurizing unit 2' are changed.

That is, the second piston 6 of the pressurizing unit 2'
A recess is provided on the outer circumferential surface of the large-diameter hole 31c, and an intermediate chamber 66 whose both ends are sealed with liquid is formed between the concave portion and the inner circumferential surface of the large-diameter hole 31c. In addition, a passage 68 that communicates between the intermediate chamber 66 and the inner peripheral portion is provided, and a port 67 for introducing master cylinder hydraulic pressure that communicates with the intermediate chamber 66 is provided in the housing of the pressurizing unit, and the port 67 is connected to the passage 22. It is connected to a passage 73 that branches off from.

The intermediate chamber 66 constantly communicates with the master cylinder chamber 21 via the passages 73 and 22, while the passage 73
The master cylinder chamber 2 is connected to the passage 22 downstream from the branch point of the master cylinder chamber 2.
The switching valve 60 is provided as means for opening and closing a passage between the first and second cylinder chambers 35. The switching valve 60 is normally in the closed position shown in the figure, and when a failure occurs in the auxiliary power source system, it is switched to the open position, and the pressurizing unit 2' is switched to the open position as in the first embodiment.
Master cylinder pressure is introduced into port 46 of.

Inside the fast fill piston 70, in order to communicate the intermediate chamber 66 and the second cylinder chamber 35, an outer circumferential groove 70a communicating with the passage 68, an L-shaped passage 70b, and a check valve chamber are provided. A valve ball 76 which forms a liquid passage consisting of 70c and is biased by a spring 75 inside the check valve chamber 70c
A passageway opening/closing means is installed. The check valve chamber 70
c has an opening at the end surface, and has a valve opening pin 77 protruding from the end surface 32b of the first piston 32 facing the opening, so that when the first piston 32 comes into contact with the fast fill piston 70, the valve opening pin 77 opens. protrudes into the check valve chamber 70c, and moves the valve ball 76 from the valve seat against the spring 75, thereby communicating the intermediate chamber 66 and the second cylinder chamber 35.

Furthermore, the passage 26 that introduced boost pressure into the port 45 opening into the first cylinder chamber 34 of the pressurizing unit 2' is provided with three positions that serve as a means for regulating the hydraulic pressure in the first cylinder chamber 34. A switching valve 61 is installed. That is,
The passage 26 is connected to a fluid pressure introduction passage 80 via a switching valve 61;
The first cylinder chamber 34 is selectively communicated with the fluid pressure outlet passage 81 connected to the reservoir 13, or the passage 2
I am trying to close 6.

Furthermore, a switching valve 6 constituting the pressure regulating means
A 2-position switching valve 62 is installed in the fluid pressure introduction passage 80 upstream of 1.
is installed, and the fluid pressure introducing passage 80 is selectively connected to the passage 20 communicating with the boost chamber 15 and the passage 82 communicating with the auxiliary drive source 3. During normal braking, the switching valves 62 and 61 are set to the illustrated positions to introduce boost pressure into the first cylinder chamber 34 of the pressurizing unit 2'. Furthermore, the fluid pressure introducing passage 80 and the fluid pressure deriving passage 8
1 is connected to a passage 83 connected to the rear wheel brake 5 via a three-position switching valve 63.

To explain the operation of the second embodiment, when the boost pressure is in normal operation, the master cylinder hydraulic pressure flows into the intermediate chamber 66 of the pressurizing unit 2' through the passages 22 and 73, while the first cylinder The first piston 32 is pressed by the boost pressure introduced into the chamber 34, and the valve opening pin 77 attached to the first piston 32 presses the valve ball 76 to open the check valve. Even when the first piston 32 is in contact with the end surface of the fast fill piston 70, a portion of the opening of the check valve chamber 70c remains open to the second cylinder chamber 25 without being closed. Therefore, the pressure fluid at the master cylinder pressure that has flowed into the intermediate chamber 66 flows into the second cylinder chamber 35,
Similar to the first embodiment, the second piston 65 is pressed by the pressure fluid of the master cylinder pressure, and is also pressed by the first piston 32 pressed by the boost pressure, and moves toward the third cylinder chamber 36. Then, the front wheel brake 4 is pressurized with this fluid pressure. On the rear wheel brake 5 side, boost pressure fluid is supplied to the rear wheel brake 5 from passages 20, 80, and 83.
and pressurize.

Next, when it becomes necessary to reduce the brake pressure for anti-lock operation, the switching valve 61 switches,
The passage 26 is communicated with the fluid pressure outlet passage 81, and the first cylinder chamber 34 is communicated with the reservoir 13. Therefore, the pressure fluid in the first cylinder chamber 34 flows back to the reservoir 13, and the pressure in the first cylinder chamber 34 is reduced. Due to this pressure reduction in the first cylinder chamber 34, the first piston 32 retreats toward the first cylinder chamber 34, and the valve opening pin 76 moves back accordingly, so that the valve ball 76 is seated on the valve seat by the spring 75. Communication between the intermediate chamber 66 and the second cylinder chamber 35 is cut off. Therefore, the pressure fluid at the master cylinder pressure flowing into the intermediate chamber 66 is no longer supplied to the second cylinder chamber 35, and as described above, since the first piston 32 retreats, the second cylinder chamber 3
5 increases, and the second cylinder chamber 35 is depressurized. Therefore, the fast fill piston 70 and the second piston 65, which are biased by the spring 39, also move into the first cylinder chamber 34.
The brake fluid pressure of the front wheel brake 4 is reduced by moving backward in the direction of , and the volume of the third cylinder chamber 36 increases.

[0053] In order to return the fast fill piston 70 and the second piston 65 to their original positions, the first piston 32 is provided with an allowance for a backward stroke. On the other hand, on the rear wheel brake 5 side, the switching valve 63 switches, and by communicating the passage 83 with the passage 81, the rear wheel brake 5
Depressurize.

For example, if it becomes necessary to pressurize the wheel brakes regardless of pedal operation due to traction control operation, etc., the switching valve 62 is switched from the position shown in the figure. With this switching operation, the fluid pressure introduction passage 80 is communicated with the auxiliary power source 3, and auxiliary power pressure is directly introduced into the rear wheel brake 5 to pressurize it. On the other hand, front wheel brake 4
On the side, auxiliary power pressure is directly introduced into the first cylinder chamber 34 of the pressurizing unit 2'. The introduction of this auxiliary power pressure presses the first piston 32, which presses the second piston 65 to move toward the third cylinder chamber 36, thereby pressurizing the front wheel brake 4. The rear brakes are directly pressurized by auxiliary power pressure.

When a failure occurs in the system of the auxiliary power source 3, the switching valve 60 is switched to directly introduce pressure fluid at the master cylinder pressure into the second cylinder chamber 35 from the passage 22. Therefore, regardless of whether the check valve in the fast fill piston 70 is open or closed, that is, the first piston 32 is not pressed by boost pressure, the valve ball 76 is not opened by the valve opening pin 77, and even if the check valve is closed. , second piston 6
5 is pressurized with pressure fluid at the master cylinder pressure introduced into the second cylinder chamber 35 and moved. Therefore, the front wheel brake 4 is pressurized as in the first embodiment. As described above, in the second embodiment, it is possible to cope with a failure of the auxiliary power source system, perform a pressure reduction operation during anti-lock, and also perform a traction control operation.

The third embodiment shown in FIG. 4 uses the same pressure unit 2' as the pressure unit 2' shown in the second embodiment, and the first cylinder chamber 34 of the pressure unit 2' is A passage 26 that communicates between the port 45 opened to the switching valve 61 and the switching valve 61
The only difference is that a switching valve 90 for opening and closing the passage is provided. When the auxiliary power pressure fails, the switching valve 90 is switched to open the passage 2.
Close 6. Therefore, by closing the passage 26, a change in volume of the first cylinder chamber 34 of the pressurizing unit 2' can be prevented, and movement of the first piston 32 in the direction of the first cylinder chamber 34 can be suppressed. Therefore, the second cylinder chamber 3
The master cylinder pressure acting on the second piston 65 acts to press the second piston 65 toward the third cylinder chamber 36, thereby making it possible to reduce the loss stroke of the master cylinder. Note that other functions are the same as those of the second embodiment, so explanations will be omitted.

[0057]

[Effects of the Invention] As is clear from the above explanation, according to the brake fluid pressure control device according to the present invention, in normal conditions, one wheel (front wheel) to which master cylinder pressure is supplied
Since the brake side is supplied with fluid in a volume corresponding to the boost pressure from the boost chamber via the pressurizing unit, it is possible to obtain good braking effectiveness with a short pedal stroke without sacrificing the rigidity of the brake. The diameter of the cylinder can be set small. Therefore, even if a defect occurs in the auxiliary power source or the circuit communicating with the auxiliary power source, the pedal force required to obtain a constant brake effect can be sufficiently reduced.

In particular, a fast fill piston is provided, and when the boost pressure increases, only the fast fill piston is moved by the first piston to close the recirculation port,
Apply pressure at the initial stage of braking. During this time, the second piston is stationary and the volume of the second cylinder chamber into which master cylinder pressure is introduced is kept constant, so the pedal does not stroke until a certain pressure is reached, which shortens the pedal stroke at the beginning of braking and gives a feeling of play. can be reduced.

As mentioned above, a brake system using this type of hydraulic booster can reduce the play at the initial stage of braking and can sufficiently reduce the pedal force required to obtain a constant braking effect. The range of vehicles to which this can be applied is not limited to those with a small weight, but can be used in a wide range of vehicles. Moreover, by configuring the first cylinder chamber of the pressurizing unit to selectively communicate with the reservoir and the auxiliary drive source, regardless of the drive system and weight distribution of the vehicle in which it is installed, anti-lock and traction control functions can be improved. A brake system can be configured.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of a brake system according to a first embodiment of the present invention.

2 is a cross-sectional view of the braking unit of the brake system of the first embodiment shown in FIG. 1. FIG.

FIG. 3 is an overall configuration diagram of a brake system according to a second embodiment of the present invention.

FIG. 4 is an overall configuration diagram of a brake system according to a third embodiment of the present invention.

FIG. 5 is a sectional view showing a conventional example.

FIG. 6 is a diagram illustrating conventional problems and goals of the present invention.

[Explanation of symbols]

1 Braking unit 2, 2' Pressure unit 3 Auxiliary drive source 4 Front wheel brake 5 Rear wheel brake 6 Master cylinder 7 Booster 13 Reservoir 15 Boost chambers 20, 23, 26 Passage 30 Housing 31 Stepped hole 32 First piston 33 Second Piston 34 First cylinder chamber 35 Second cylinder chamber 36 Third cylinder chamber 37 Fast fill piston 40 Valve bodies 42, 43, 45, 46, 67 Ports 60, 61,
62, 63, 90 Switching valve 65 Second piston 66 Intermediate chamber 80 Fluid pressure introduction passage 81 Fluid pressure derivation passage

Claims (6)

[Claims] [Claim 1] A master cylinder that is driven by a pedal force applied to a brake pedal and generates brake fluid pressure, an auxiliary power source that sucks and pressurizes fluid from a reservoir and constantly stores it as auxiliary power pressure, and a boost chamber, When the brake pedal is operated, boost pressure is generated in the boost chamber in proportion to the pedal force in response to auxiliary power pressure from the auxiliary power source, and this boost pressure assists the thrust of the master cylinder due to the pedal force. A brake fluid pressure control device having a hydraulic pressure booster configured to be able to use brake pressure as brake pressure, a housing having a large diameter hole and a small diameter hole in series, and a housing that is slidably fitted into the small diameter hole. a first piston that is slidably fitted into the large diameter hole and that allows liquid to flow through the large diameter hole into the second cylinder chamber and the third cylinder chamber; a second piston that seals and separates; and a fast-fill piston that penetrates the second piston in a fluid-sealed and slidable manner and has a collar portion extending toward the end surface of the second piston at the tip on the third cylinder chamber side. a means for urging the fast-fill piston toward a second cylinder chamber; a port connecting the first cylinder chamber to a passage communicating with the boost chamber; and a passage communicating the second cylinder chamber with the master cylinder. a port connected to a passage communicating the third cylinder chamber with one or more wheel brakes; a port communicating the third cylinder chamber with an open passage communicating with a reservoir; A pressurizing unit is provided in which an opening/closing means for a port communicating with the three cylinder chambers is connected to the fast fill piston, and when the boost pressure is normal, the first piston receiving the boost pressure moves the fast fill piston to close the opening/closing means. After the valve is closed, the fluid in the third cylinder chamber is supplied to the wheel brake only by the phalt fill piston until a certain stroke, and the fluid in the third cylinder chamber is pressurized. After that, the first piston is brought into contact with the second piston to generate boost pressure. The master cylinder pressure moves to the third cylinder chamber side, and the pressure fluid in the third cylinder chamber is supplied to the wheel brakes and pressurized. However, when boost pressure fails, only the master cylinder fluid pressure is applied to the second piston and the fast fill piston. A brake fluid pressure control device characterized in that the second piston and the fast fill piston are moved by acting on the area, the opening/closing means is closed, and a wheel brake is pressurized. 2. The diameter of the fast-fill piston and the diameter of the first piston are set to be the same, and after the first piston moves the fast-fill piston and closes the reflux port by the opening/closing means, the first piston comes into contact with the second piston. 2. The brake fluid pressure control device according to claim 1, wherein the volume of the second cylinder chamber into which the master cylinder pressure between the second piston and the first piston is introduced is maintained constant until the second piston and the first piston come into contact with each other. 3. A first cylinder provided in the middle of the passage communicating the first cylinder chamber and the boost chamber, selectively communicating the first cylinder chamber with the boost chamber and the reservoir, and also capable of closing the passage. a pressure regulating means for regulating the hydraulic pressure in the first cylinder chamber; a passage opening/closing means provided in the middle of the passage communicating the master cylinder and the second cylinder chamber; and an intermediate chamber liquid-sealed by both ends of the second piston. and a passage communicating the intermediate chamber and the master cylinder, and the second
A passage provided inside the piston or fast-fill piston that communicates an intermediate chamber with a second cylinder chamber, and a means for opening and closing communication between the intermediate chamber and the second cylinder chamber are provided, and anti-static pressure is provided when the auxiliary power pressure is normal. 3. The brake fluid pressure control device according to claim 1, wherein the brake fluid pressure control device is configured to perform a locking operation. 4. The brake fluid pressure control device according to claim 3, wherein the first piston is configured to be able to move further toward the first cylinder chamber than the rest position of the second piston. 5. Means is provided upstream of the pressure regulating means in the middle of a passage communicating the first cylinder chamber and the boost chamber, and selectively opens and closes the downstream circuit and the passage of the auxiliary power source. The brake fluid pressure control device according to claim 3, characterized in that: 6. The brake fluid pressure control device according to claim 4, wherein the first piston is configured to remain at a rest position when the auxiliary power fails.