JPH11286269A - Hydraulic brake power assist and hydraulic brake power assist system using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a brake assist at a low cost with a simple structure by use of a hydraulic brake power assist having a hysteresis. SOLUTION: In the forward advance of an input shaft 21, the pressure of the reaction chamber 30 is held at the atmospheric pressure since a hydraulic fluid is introduced for a reservoir 9 to a reaction chamber 30 through a twelfth check valve. In the backward advance of the input shaft 21, the reaction chamber 30 is held at the wheel cylinder pressure since the hydraulic fluid of the reaction chamber 30 is discharged to wheel cylinder side through a thirteenth check valve 75 and a passage 74. Since the pressure of the reaction chamber 340 acts on the rear end of a reaction piston 23 making contact with the stepped part of the input shaft 21, a hydraulic brake power assist 2 has a hysteresis. The hydraulic pressure is introduced to a power chamber 25 through a pressure inlet port 69 when a brake assist is required, whereby the brake force is increased. In this case, the hydraulic pressure of the power chamber 24 is variously controlled within the hysteresis range of the hydraulic brake power assist 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic booster for boosting an input to a predetermined magnitude by hydraulic pressure and outputting the same, and a large brake force with a small operating force by using the hydraulic booster. Hydraulic booster having a large hysteresis between the operating direction and the deactivating direction, and a brake provided by the hysteresis of the hydraulic booster. It belongs to the technical field of a brake hydraulic booster system having an assist function.

[0002]

2. Description of the Related Art An automobile brake hydraulic booster system is
This is a system that obtains a large braking force with a small depressing force of the brake pedal by a hydraulic booster. In this brake hydraulic booster, when the brake wheels tend to lock,
Anti-lock control (hereinafter, also referred to as ABS control) that adjusts the WCY pressure of a wheel cylinder (hereinafter, also referred to as WCY) so as to eliminate the locking tendency. Traction control (Traction) that automatically applies brakes to the drive wheels to eliminate the
Control; hereinafter, also referred to as TRC control), a cornering attitude control (Vehicle Stability Control;) that automatically applies a brake to inner wheels when the vehicle turns to control the attitude of the vehicle.
Hereinafter, also referred to as VSC control) and auto cruise control (Auto Cruis) that automatically applies a brake to wheels to control the speed so that the vehicle runs at a constant speed.
e Control (hereinafter, also referred to as ACC control) has been developed.

FIG. 10 is a diagram showing an example of such a conventional brake hydraulic boosting system. In the figure, 1 is a brake hydraulic booster, 2 is a brake hydraulic booster, 3 is a master cylinder (hereinafter also referred to as MCY), 4, 5, 6,
7 is divided into two systems, and WCYs for generating braking force (WCYs 4 and 5 are provided for driving wheels, and WCYs 6 and 7 are provided for non-driving wheels. ), 8 are ABS control, TRC control, VSC
Two systems of brake pressure control devices for performing control and ACC control, 9 is a reservoir for storing brake fluid, and 10 is a brake pedal.

[0004] The brake hydraulic booster 2 is conventionally known, and FIG. 11 shows an example thereof. In the figure, 11
Is a housing, 12 is a plug, 13 is a power piston,
14 is a control valve, 15 is a valve seat member, 16 is a cylindrical fixing member,
17 is a nut, 18 is a ball valve, 19 is a valve body, 20 is a valve operating member made of a cylindrical member, 21 is a brake pedal 10
The input shaft 21a is connected to the input shaft 21a.
Is a cylindrical stopper member, 22a is a stopper of the cylindrical stopper member 22, 23 is a reaction force piston, 23a is a first flange of the reaction force piston 23, and 23b is a second flange of the reaction force piston 23.
A flange, 23c is a rear end of the reaction force piston 23, 24 is a spring for biasing the reaction force piston 23, 25 is a power chamber,
26 is an input port to which hydraulic pressure is constantly introduced, 27 is a hydraulic pressure discharge passage constantly communicating with the reservoir 9, 28 is an output shaft,
29 is a return spring, 30 is a reaction force chamber, 31 is a pump (driven by a motor M; hereinafter, also referred to as a first pump corresponding to a second pump 62 described later), and 32 is always in communication with the input port 26. This is an accumulator that stores the hydraulic pressure.

An MCY 3 is a conventional well-known general tandem type master cylinder. Although not shown, a primary piston operated by an output shaft 28 of the brake hydraulic booster 2 and an MCY pressure generated by the advance of the primary piston. A first hydraulic chamber, a secondary piston operated by the MCY pressure of the first hydraulic chamber, and a second hydraulic chamber in which the MCY pressure is generated by the advance of the secondary piston. Then, as shown in FIG. 10, the first passage 33 connected to the first hydraulic chamber is connected to one of the systems (that is, the drive system) via the first and second branch passages 33a and 33b of the first passage 33. Each WCY4,5
It is connected to the. Similarly, the second passage 34 connected to the second hydraulic chamber, and each of the other systems (that is, the non-drive wheel systems) via the first and second branch passages 34a and 34b of the second passage 34, respectively. It is connected to WCY6,7.

[0006] The brake pressure control device 8 is a conventionally known return pump type device which returns the brake fluid discharged from the W / C to the MCY3 side. Reference numeral 38 denotes a first to fourth holding valves formed of normally open electromagnetic on / off valves, and reference numerals 39, 40, 41, and 42 denote first to fourth holding valves.
First to fourth check valves 43, 44, 45, provided in parallel with the fourth to fourth holding valves 35, 36, 37, 38;
46 is a first to fourth discharge passage for discharging the brake fluid of the W / C 4, 5, 6, 7 to the reservoir 9, 47 and 48 are third and fourth passages, and 49, 50, 51, 52 are first to fourth. 4th
First to fourth discharge valves 53, which are normally closed solenoid on-off valves provided in the discharge passages 43, 44, 45, 46, respectively, are joined to the first and second discharge passages 43, 44 and the third passage 47. Connecting the point to the first passage 33 and the first pump 31
Is a sixth passage connecting the junction of the third and fourth discharge passages 45 and 46 and the fourth passage 48 with the second passage 34, and 55 and 56 are fifth passages. 5
5 and 6 provided with the first pump 31 therebetween.
Check valve 57 is the sixth check valve 56 and the first
A pump discharge liquid supply control valve 58, which is a normally-closed electromagnetic on-off valve, provided in a fifth passage 53 between the passage 33 and the input passage 26 of the brake hydraulic booster 2, the sixth check valve 56, A seventh passage connecting the fifth passage 53 between the pump discharge liquid supply control valves 57 and provided with the accumulator 32, and a seventh passage 59 and 60 provided in the seventh passage 58 with the accumulator 32 interposed therebetween. An eighth check valve, 61 is a relief valve for controlling the accumulator 3 to a predetermined pressure, 62 is a second pump provided in the sixth passage 54, 6
Ninth and tenth check valves 3 and 64 are provided in the sixth passage 54 with the second pump 62 interposed therebetween, and 65 and 66 are provided in the first and second passages 33 and 34, respectively. Are the first and second differential pressure valves each including a normally-open solenoid valve in which is set.

In the brake hydraulic booster 1, when the brake is not operated, all the components are set to the non-operating state shown in FIGS. In this non-operating state, the ball valve 18 of the control valve 14 is
5 and the distal end of the valve operating member 20 is separated from the ball valve 18. Therefore, the power room 25
Is the input port 2 which is always connected to the accumulator 32
6 and is connected to the reservoir 9 via the hydraulic pressure discharge passage 27, the hydraulic pressure is not introduced into the power chamber 25 and the power chamber 25 is at atmospheric pressure, and the power piston 13 does not operate. For this reason, MCY3 does not work,
No MCY pressure is generated.

[0008] From this inoperative state, the brake pedal 10
When the normal brake operation is performed by depressing the
As 1 advances, the valve operating member 20 also advances, and the tip of the valve operating member 20 comes into contact with the ball valve 18 of the control valve 14 and pushes the ball valve 18 to separate from the valve seat member 15. Then, the power chamber 25 is connected to the input port 26 and cut off from the reservoir 9, pressure fluid is introduced into the power chamber 25, and the power piston 13 operates. By the operation of the power piston 13, the brake hydraulic booster 2 outputs from the output shaft 28. With this output, the MCY 3 is operated and M
Generates CY pressure. When the hydraulic pressure of the power chamber 25 reaches a magnitude corresponding to the input, the ball valve 18 is seated on the valve seat member 15, and
Since the power chamber 25 is shut off from both the input port 26 and the reservoir 9, the output of the brake hydraulic booster 2 is:
It becomes the size which boosted the input.

One MCY pressure generated in MCY3 is
The W / Cs 4, 5 on the driving wheel side are introduced through the first passage 33, the first differential pressure valve 65, the first and second branch passages 33a, 33b, and the first and second holding valves 35, 36. Further, the other MCY pressure passes through the second passage 34, the second differential pressure valve 66, the first and second branch passages 34a and 34b, the third and fourth holding valves 37 and 38, and the W / W / C6,7 are introduced.

The hydraulic pressure in the power chamber 25 causes the reaction piston 2
3 is pressed backward against the spring 24, but the spring 24 contracts in an initial stage in which the hydraulic pressure in the power chamber 25 is still small and the brake system does not eliminate the loss stroke and substantially does not generate braking force. Instead, the rear end 23c of the reaction force piston 23 does not abut on the step portion 21a of the input shaft 21, so that a jumping action is performed by servo control having an extremely large boosting ratio, that is, a servo ratio, as shown in FIG.

When the hydraulic pressure in the power chamber 25 becomes a predetermined pressure and the spring 24 contracts, the rear end 23 of the reaction force piston 23
c contacts the step 21a of the input shaft 21, and the jumping action ends. At this stage, the loss strokes of the W / Cs 4, 5, 6, and 7 are eliminated, and the braking force is substantially generated. At this time, the servo ratio is reduced to the servo ratio of the normal brake, and thereafter, the brake hydraulic pressure is reduced. The booster 2 generates an output in which the input is boosted at this servo ratio, that is, performs servo control during normal braking along the line of the servo ratio of the normal brake in FIG.

When the hydraulic pressure in the power chamber 25 reaches the maximum pressure determined by the accumulated pressure of the accumulator 32 and does not increase any more, the brake hydraulic booster 2 becomes full load and does not perform servo control. In FIG. 12, the output of the brake hydraulic booster 2 has such a magnitude that the output increase based on the input increase along the full load line in FIG. 12 is not boosted.

When the brake pedal 10 is released, the input shaft 21 is retracted, so that the valve operating member 20 is also retracted, and the tip of the valve operating member 20 is separated from the ball valve 18 of the control valve 14. As a result, the power chamber 25 is connected to the reservoir 9, the pressure fluid introduced into the power chamber 25 is discharged to the reservoir 9 via the hydraulic pressure discharge passage 27, and the power piston 13 is retracted by the return spring 29. Until the hydraulic pressure in the power chamber 25 reaches the maximum pressure determined by the accumulated pressure in the accumulator 32, the output decreases along the full load line as the input decreases, as shown in FIG. Further, when the hydraulic pressure of the power chamber 25 falls below this maximum pressure, the output decreases along the line of the normal servo ratio, and the hydraulic pressure of the power chamber 25 further decreases, and the reaction force piston 23 is caused by this hydraulic pressure. When the pushing force is smaller than the spring force of the spring 24, the reaction force piston 23
Moves forward with respect to the input shaft 21, and the rear end 23 c of the reaction force piston 23 moves away from the step 21 a of the input shaft 21. As a result, the output of the brake hydraulic booster 12 decreases from the normal servo ratio line to the jumping characteristic line having a large servo ratio. In response to the decrease in the output of the brake hydraulic pressure booster 2, the MCY pressure decreases, and the braking force decreases.

When the cylindrical stopper member 22 fixed to the input shaft 21 comes into contact with the stopper 12a of the plug 12, the input shaft 21 does not retreat any more, reaches the retreat limit, and returns to the inoperative state shown in the figure. When the hydraulic pressure in the power chamber 25 is completely discharged, the power piston 13 also returns to the non-operating state shown in FIG.
The brake hydraulic booster 2 does not output, and the MCY 3 is also in an inactive state. Thus, the brake is released.

In the conventional brake hydraulic booster 2, as shown in FIG. 12, the input / output characteristics follow the same path on the rising side and the falling side of the input, and have substantially no hysteresis. Become.

The brake pressure control device 8 reduces, maintains, and reduces the brake pressure in order to eliminate the tendency of the brake wheels to lock.
ABS control by pressure increase is performed. That is, based on a wheel speed signal of each wheel from a wheel speed sensor (not shown), the electronic control device (not shown) detects the locking tendency of at least one of the wheels at the time of braking, and the first to fourth holding valves 35 and 36. , 37, 38 are closed. Thereby, each W /
The W / C pressures of C4, 5, 6, and 7, that is, the brake pressure are held, and the increase in the braking force stops. When the locking tendency of the wheels is not eliminated even by the holding of the brake pressure, the electronic control unit controls the first to fourth discharge valves 49, 50,
Of the 51 and 52, the discharge valve corresponding to the wheel that tends to lock is opened. Then, the W / C corresponding to the wheel is connected to the reservoir 9, the hydraulic fluid in the W / C is discharged to the reservoir 9, and the brake pressure of the W / C is reduced. When the wheel speed of the wheel that tends to lock recovers to a predetermined speed due to the reduction in the brake pressure, the electronic control unit starts the motor M
To operate the first and second pumps 31 and 62 at the same time, close the open discharge valve, and
5, 36, 37 and 38 are opened, and the pump discharge liquid supply control valve 57 is further opened. Thereby, the first and second pumps 3
1, 62 supplies the brake fluid from the reservoir 9 to the MCY3 side, and the brake pressure is increased by the MCY pressure. When the wheel becomes locked again due to the increase in the brake pressure, the above-described holding, depressurization and pressure increase of the brake pressure are repeated until the locking tendency is completely eliminated.
ABS control is performed.

Further, the brake pressure control device 8 performs TRC control by applying a brake to the drive wheels to eliminate the tendency of the drive wheels to spin. That is, based on the wheel speed signal of the drive wheel from the wheel speed sensor for the drive wheel, the electronic control unit drives the motor M when detecting the idling tendency of at least one drive wheel at the time of starting or accelerating. Pump 31
And at the same time, the pump discharge liquid supply control valve 57 is opened, the first differential pressure valve 65 is switched to the relief position, and one of the first and second holding valves 35 and 36 corresponding to the driving wheel that does not tend to run idle. Close the valve. Then, the first pump 31 supplies the brake fluid from the reservoir 9 to the W / C corresponding to the driving wheel that tends to run idle, so that the driving wheel is braked.

At this time, the electronic control unit controls the opening and closing of the holding valve and the discharge valve corresponding to the driving wheels that tend to run idle, to supply the liquid discharged from the pump to the W / C, and to control the W / C.
, The brake pressure is adjusted according to the tendency to slip. As a result, the rotational driving force of the driving wheel is weakened, and the tendency of idling is suppressed. When the pump discharge pressure becomes higher than a predetermined value, a part of the pump discharge pressure is reduced by the relief operation of the differential pressure valve 65 to the differential pressure valve 65, the first hydraulic pressure chamber 83 of the inactive MCY3, and the brake fluid compensation port 87. The pressure is discharged to the reservoir 9 via the reservoir 9 and the discharge pressure of the pump is controlled to a predetermined pressure. At the relief position of the differential pressure valve 65, the W / C
The flow of the brake fluid to the 4 and 5 sides is blocked.

By applying a brake to the drive wheels that tend to idle, TRC control is performed until the rotational driving force of the drive wheels is adjusted and the tendency to idle is completely eliminated. When the motor M is driven during the TRC control, the second pump 62 on the non-driven wheel is also operated, but the pump discharges the second differential pressure valve 66 in the open position and the MC
Since it is sent to the reservoir 9 via Y3, the brake of the non-driving wheel does not operate.

Further, the brake pressure control device 8 performs VSC control by operating a brake on the inner wheel to control the posture of the vehicle when turning. That is, the electronic control unit detects the turning of the vehicle based on a wheel speed signal from each wheel speed sensor of the inner and outer wheels at the time of turning of the vehicle or a steering angle signal from a steering angle sensor (not shown) for detecting steering of the steering wheel. Then, the motor M is driven to operate the first and second pumps 31 and 62, and at the same time, the pump discharge liquid supply control valve 57 is opened, and the first and second differential pressure valves 65 and 66 are respectively switched to the relief positions. Close the holding valve corresponding to the outer ring side. Then, the first and second pumps 31, 62 supply the brake fluid from the reservoir 9 to the W / C corresponding to the inner wheel, so that the inner wheel brake is operated. At this time, the electronic control unit controls the opening and closing of the holding valve and the discharge valve corresponding to the inner ring side to supply the liquid discharged from the pump to the W / C,
Further, the brake pressure is adjusted according to the traveling speed and the steering angle during turning by discharging the brake fluid from the W / C to the brake fluid pressure reservoir. Due to this, the speed of this inner ring decreases,
The vehicle attitude at cornering is controlled. By applying a brake to the inner wheel when the vehicle turns, the VSC control is performed until the inner wheel speed is adjusted and the tendency to idle is completely eliminated.

Further, the brake pressure control device 8 controls the vehicle by operating the brakes on the respective wheels in order to drive the vehicle at a constant speed.
Performs CC control. That is, when the constant speed traveling of the vehicle is set, the electronic control unit detects that the vehicle speed has become equal to or higher than the set speed set in the constant speed traveling based on the wheel speed signal from each wheel speed sensor, When the first pump 31 is operated by driving the motor M, the pump discharge liquid supply control valve 5
7 is opened, and the first differential pressure valve 65 is switched to the relief position. Then, since the first pump 31 supplies the brake fluid from the reservoir 9 to the W / C corresponding to the drive wheel, the brake of the drive wheel operates. At this time, the electronic control unit controls the opening and closing of the holding valve and the discharge valve corresponding to the driving wheels,
The brake pressure is adjusted according to the difference between the vehicle speed and the set speed by supplying the discharge liquid from the pump to the W / C and discharging the discharge liquid from the W / C to the brake fluid pressure reservoir. As a result, the vehicle speed decreases and is controlled to the set speed. When the vehicle speed exceeds the set speed during the constant speed running, the ACC control is performed by applying a brake to the drive wheels so that the vehicle speed becomes the set speed. In addition, instead of the first and second differential pressure valves 65 and 66, a valve using a normally-open electromagnetic on-off valve may be used.

[0022]

By the way, in a brake system, it is desirable that a large braking force can be generated as quickly as possible during a sudden brake as compared with a normal brake. Also, it is necessary to generate a large braking force at the time of sudden braking, but some drivers, such as beginners, who are not used to driving a car,
In some cases, the brake pedal cannot be depressed significantly, and a large braking force cannot be generated.
In such a case, it is desirable that even a driver such as a beginner who is not accustomed to driving can perform brake assist in order to surely generate a large braking force. In this case, it is preferable to enable the brake assist with a simple configuration by using conventional parts as much as possible without requiring a dedicated part for the brake assist.

However, in the brake hydraulic booster 2 in the brake hydraulic booster 1 described above, FIG.
As shown in the above, the servo ratio in the servo control in which the brake operation is substantially performed is constant, so not only can not generate a large braking force earlier than during normal braking at the time of sudden braking, but also are not used to driving It is not possible to assist a person to reliably generate a large braking force, and it is difficult to reliably meet the above-mentioned demand.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an inexpensive hydraulic booster having a simple configuration and hysteresis. Another object of the present invention is to provide a brake hydraulic pressure boosting system capable of performing brake assist at a low cost with a simple configuration.

[0025]

In order to solve the above-mentioned problems, a hydraulic booster according to the first aspect of the present invention comprises a hydraulic pressure source for generating hydraulic pressure, a reservoir for storing hydraulic fluid, and an output. The generated power piston, the power chamber facing the pressure receiving surface of the power piston, and the power chamber shut off from the hydraulic pressure source and shut off when not operating, and the power chamber is shut off from the reservoir when operating. A control valve that communicates with the hydraulic pressure source to introduce the hydraulic fluid from the hydraulic pressure source into the power chamber; and controls operation of the control valve by moving forward when activated and retracting when deactivated. A stepped input shaft having a small diameter on the valve side and a large diameter step on the side opposite to the control valve, and an outer diameter larger than the diameter of the part of the input shaft opposite to the control valve. The input shaft is set and formed in a cylindrical shape. A reaction piston slidably fitted to the small-diameter portion, the front end of which faces the power chamber, and the rear end of which can abut against the step of the input shaft; Reaction chamber is formed so that
The reaction force chamber is provided with pressure control means for introducing different pressures when the input shaft moves forward and when the input shaft moves backward.

The pressure introduced into the reaction chamber when the input shaft moves forward is atmospheric pressure, and the pressure introduced into the reaction chamber when the input shaft moves backward is the same as that of the first embodiment. It is characterized by a pressure corresponding to the output of the power piston. Further, the invention according to claim 3 is characterized in that a buffer member is provided at a step portion of the input shaft or a rear end of the reaction force piston.

Further, a brake hydraulic booster system according to a fourth aspect of the present invention includes a hydraulic booster according to the second or third aspect,
A master cylinder having a master cylinder piston for generating a master cylinder pressure by an output of the hydraulic booster, a brake cylinder for generating a braking force by introducing the master cylinder pressure, and a second cylinder for generating a hydraulic pressure. And introducing the hydraulic pressure from the second hydraulic pressure source into the power chamber during operation without passing through the control valve.
A hydraulic pressure supply valve comprising an electromagnetic valve, and an electronic control unit for controlling the operation of the hydraulic pressure supply valve when necessary,
A first check valve, wherein the pressure control means is provided in a passage connecting the reaction chamber to the reservoir, and allows only a flow of hydraulic fluid from the reservoir to the reaction chamber; A second check valve is provided in a passage connected to the brake cylinder and allows only a flow of hydraulic fluid from the reaction chamber toward the brake cylinder.

Further, according to a fifth aspect of the present invention, a hydraulic pressure discharge passage for discharging the hydraulic fluid in the power chamber to the reservoir is connected to the reaction chamber, and the hydraulic fluid in the power chamber receives the reaction fluid. The hydraulic fluid of the chamber, the second check valve, and the brake cylinder is discharged to the reservoir via a passage that is discharged to the reservoir.

Further, the invention of claim 6 is characterized in that the effective pressure receiving area of the power piston and the effective pressure receiving area of the master cylinder piston are set to be equal. Further, the invention according to claim 7 is characterized in that the electronic control unit controls the hydraulic pressure supply valve according to an operation speed of an operation member for operating the input shaft or an operation force of the operation member.

Further, the invention according to claim 8 is provided with at least one of an antilock control system, a traction control system, a cornering attitude control system and an auto cruise control system, wherein the second hydraulic pressure source is the control system. And is also used as a hydraulic pressure source.

[0031]

According to the present invention, the pressure control means introduces different pressures into the reaction chamber when the input shaft is moved forward and when the input shaft is moved backward. The input / output characteristics of the hydraulic booster differ between the operation direction and the operation release direction due to the pressure of the reaction force chamber acting on the rear end of the reaction force piston abutting on the step of the input shaft. It comes to have hysteresis mechanically.

In particular, according to the invention of claim 2, the servo ratio of the hydraulic booster has an input / output characteristic having a hysteresis that becomes smaller in the operation direction and becomes larger in the release direction, and the hysteresis is the output of the hydraulic booster. It will be according to.
Further, according to the third aspect of the present invention, the contact noise when the reaction force piston contacts the step of the input shaft is suppressed.

Further, in the inventions of claims 4 to 8, the hysteresis characteristic of the hydraulic booster and the hydraulic pressure of the second hydraulic pressure source make it possible to increase the braking force when brake assist is required. The magnitude of the braking force for the same input can be variously controlled within the range of the hysteresis of the input / output characteristics of the hydraulic booster.

In particular, according to the sixth aspect of the invention, since the effective pressure receiving areas of the power piston and the master cylinder piston are set to be equal to each other, the hydraulic pressure of the brake cylinder and the hydraulic pressure of the power chamber are maintained at the same pressure while being balanced. It will rise.

According to the seventh aspect of the present invention, it is possible to increase the braking force according to the operating speed and operating force of the operating member. Therefore, when the brake assist is required at the time of sudden braking or the like, the brake assist is reliably performed.

Further, according to the present invention, as a second hydraulic pressure source for hydraulic pressure introduced into the power chamber at the time of brake assist, ABS control, TR, which has already been conventionally mounted, are conventionally provided.
Since the pump 31 for performing the C control, the VSC control, and the ACC control is also used, the brake hydraulic booster system has the brake assist function at a lower cost without increasing the number of parts.

[0037]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a first example of an embodiment of a brake hydraulic booster system according to the present invention.
FIG. 3 is a sectional view showing a brake hydraulic booster in the brake hydraulic booster of the first example, and FIG. 3 is a partially enlarged sectional view showing a brake hydraulic booster shown in FIG. 2 in a partially enlarged manner. is there. The same components as those in the conventional example shown in FIGS. 10 and 11 are denoted by the same reference numerals, and detailed description thereof will be omitted.

The brake hydraulic booster system 1 of the first embodiment
As shown in FIGS. 2 and 3, the brake hydraulic booster 2 is provided with an MCY 3 integrally therewith, and the housing of the MCY 3 is common to the housing 11 of the brake hydraulic booster 2. Has been.

A relatively long stepped hole 67 is formed in the housing 11 so as to open at the rear end (right end in FIG. 2) of the housing 11, and a small diameter portion 67a of the stepped hole 67 is formed. It extends from the brake hydraulic booster 1 to the MCY2 with a constant cross-sectional area. Small diameter portion 67a of stepped hole 67
In addition, a power piston 13 is disposed in a liquid-tight and slidable manner. Further, the housing 11 is provided with a pressure inlet 69 communicating with the power chamber 25 via the passage hole 68. As shown in FIG. 1, the pressure introduction port 69 is connected to the first branch passage 33a through a passage 70,
0, a normally closed solenoid valve on-off valve 71 and an eleventh check valve 7 from the solenoid valve on-off valve 71 to the pressure inlet 69 side.
2 are provided. The electromagnetic valve opening / closing valve 71 constitutes the hydraulic pressure supply valve of the present invention.

Further, the reservoir 9 is provided in the hydraulic pressure discharge passage 27.
A twelfth check valve 73 that allows only the flow of the brake fluid from the brake fluid booster 2 to the brake fluid pressure booster 2 is provided. The hydraulic pressure discharge passage 27 closer to the power chamber 25 than the twelfth check valve 73 is connected to the first branch passage 74 via the fifth branch passage 74.
The fifth branch passage 7 is connected to the branch passage 33a.
A thirteenth check valve 75 is provided in the thirteenth valve and permits only the flow of the brake fluid from the hydraulic pressure discharge passage 27 toward the first branch passage 33a. These twelfth and first
The output shaft 28 of the brake hydraulic booster 2 abuts against the primary piston 76 of the MCY 3 and the power piston 13
The primary piston 76 is pressed at the time of operation. The brake hydraulic booster 2 of the first example
Then, the power piston 13 in the conventional example shown in FIG.
The return spring 29 is omitted.

Further, the valve operating member 20 and the cylindrical stopper member 22 are formed integrally. That is, the stopper portion 22a is formed on the valve operating member 20. Other configurations of the brake hydraulic booster 2 of the first example are the same as those of the conventional example of FIG.

On the other hand, the MCY 3 has substantially the same configuration as a conventional general tandem MCY including a primary piston 76 and a secondary piston 77 set to the same effective pressure receiving area as the power piston 13. ing. These pistons 76, 77 are both provided in a small diameter portion 67a of the stepped hole 67 in a liquid-tight and slidable manner. The maximum distance between the pistons 76 and 77 is regulated by the distance regulating means 78. The pistons 76 and 77 are urged in a direction to be separated from each other by a spring 79 contracted between them, and are set at a maximum interval shown in the drawing when not in operation.

A cup seal 80 is provided at a front end of the primary piston 76, and cup seals 81 and 82 are provided at a rear end and a front end of the secondary piston 77, respectively. The first hydraulic chamber 83 is provided in the small-diameter portion 4a between the two cup seals 80 and 81.
And a second hydraulic chamber 84 is defined in the small diameter portion 4a in front of the cup seal 82. First
The hydraulic pressure chamber 83 is provided in the first passage 33, that is, the W / C4 on the drive wheel side,
5, and the second hydraulic chamber 84 is connected to the second passage 34, that is, the W / C 6, 7 on the non-driving wheel side.

The housing 11 on the MCY3 side is provided with brake fluid supply ports 85 and 86 and brake fluid compensation ports 87 and 88, respectively.
5, 86 and the brake fluid compensation ports 87, 88 are always in communication with the reservoir 9. And the primary piston 76
When the secondary piston 77 is in the inoperative position, the cup seal 80 is located between the brake fluid supply port 85 and the brake fluid compensation port 87. It is arranged between the port 86 and the brake fluid compensation port 88. Therefore, when not operating, the fluid freely flows in both directions between the first hydraulic pressure chamber 83 and the brake fluid compensation port 87 and between the second hydraulic pressure chamber 84 and the brake fluid compensation port 88, respectively. I have.

In operation, when both pistons 76 and 77 advance, and cup seals 80 and 82 pass brake fluid compensation ports 87 and 88, respectively, the first and second pistons 76 and 77 move.
The flow of the liquid from the hydraulic pressure chambers 83 and 84 to the reservoir 9 is blocked, respectively. Further, when the pistons 76 and 77 are retracted from the operating state, the brake fluid of the reservoir 9 is supplied to the respective brake fluid supply ports 85 and 86 and Through the axial holes 89 and 90 formed in the pistons 76 and 77, respectively,
And the second hydraulic chambers 83 and 84 are supplied.

In the second hydraulic chamber 84, there is provided a return spring 91 for constantly urging the secondary piston 77 in the direction of the non-operation position. Other configurations of the brake hydraulic booster 1 of the first example are the same as those of the conventional example shown in FIGS.

Next, the operation of the brake hydraulic booster system 1 of the first example configured as described above will be described. When the brake is not operated, each component of the brake hydraulic booster 1 is in the state shown in FIGS. 1 to 3.

When a normal brake operation is performed by depressing the brake pedal 10, pressure fluid is introduced into the power chamber 25 as in the above-described conventional example, and the power piston 13 boosts the pedal depressing force and outputs the same. Is M via the output shaft 28
It is transmitted to the primary piston 76 of CY3, and the primary piston 76 moves forward. When the cup seal 80 passes through the brake fluid compensation port 87 as the primary piston 76 advances, an MCY pressure is generated in the first hydraulic chamber 83, and the secondary piston 77 advances by the MCY pressure. Cup seal 8 with advance of secondary piston 77
2 passes through the brake fluid compensation port 88, the second hydraulic chamber 8
MCY pressure is generated in 3. The MCY pressures in the first and second hydraulic chambers 83, 84 are respectively W / C 4, 5, 6,
7 and the normal brake is operated. At this time, since the effective pressure receiving areas of the pistons 13, 76, 77 are equal,
The hydraulic pressure in each of the chambers 25, 83, 84 becomes equal.

The input / output characteristics of the brake hydraulic booster 2 are exactly the same as those of the above-described conventional example in the operation direction, as shown in FIG. 4, and the jumping control is performed in the initial stage of the brake operation. Servo control with a normal servo ratio is performed, and then full load control is performed.

When the depressing force of the brake pedal 10 is reduced and the brake release operation is performed, the input shaft 21 is retracted, the control valve 14 is switched, and the pressure fluid in the power chamber 25 is reduced, as in the above-described conventional example. It is about to be discharged through the hydraulic discharge passage 27. However, since the flow of the pressurized liquid is blocked by the twelfth check valve 73, it is not directly discharged to the reservoir 9. On the other hand, at this time, the hydraulic pressure of the power chamber 25 is a pressure that keeps the rear end 23c of the reaction piston 23 in contact with the step portion 21a of the input shaft 21. At the same time, the reaction force piston 23 retreats together. For this reason, the volume of the reaction force chamber 30 is reduced,
On the brake hydraulic booster 2 side from the check valve 73,
The hydraulic pressure in the hydraulic discharge passage 27 including the reaction force chamber 30 increases. Then, the thirteenth check valve 75 opens, and the pressure fluid in the power chamber 25 passes through the passage 74 to the first branch passage 33a.
That is, it is discharged to the W / C 4,5 side. Therefore, the pressure in the reaction force chamber 30 is reduced under the same pressure as the W / C pressure.

On the other hand, the pressure of the reaction force chamber 30 is opposed to the hydraulic pressure of the power chamber 25 acting on the reaction force piston 23 at the rear end 23c of the reaction force piston 23 (in the same direction as the input of the input shaft 21). The brake hydraulic pressure booster 2
The rear end 23c of the reaction force piston 23 is
a, and the servo ratio becomes substantially the same as the servo ratio at the time of the jumping characteristic.

Assuming that the brake release operation is performed from the full load state of the brake hydraulic booster 2, the input / output characteristics of the brake hydraulic booster 2 in the operation release direction are as shown in FIG. The output drops along the full load line as the input decreases, and then the full load state of the brake hydraulic booster 2 continues even when the output reaches the position of the line with the normal servo ratio in the operating direction. Thus, the output does not fall along the normal servo ratio line, but falls along the full load line.

When the output reaches the position of the line of the servo ratio of the jumping characteristic, thereafter, the output falls along the line of the servo ratio of the jumping characteristic. When the output decreases and the urging force of the spring 24 for urging the reaction force piston 23 becomes larger than the pressing force of the power chamber acting on the reaction force piston 23 due to the hydraulic pressure, the reaction force piston 23 moves with respect to the input shaft 21. Move forward, rear end 2 of reaction force piston 23
3c is separated from the step 21a of the input shaft 21 and returns to the non-operation state. Thus, the brake hydraulic booster 2
The path of the input / output characteristics is different between the operation direction and the operation release direction, and has a large hysteresis.

The brake hydraulic booster 2 of the first example has a hysteresis as described above.
The output for the same input can take various output values within the range of hysteresis for that input (the range indicated by the arrow in FIG. 4). That is, by appropriately adjusting the pressure of the reaction force chamber 30, it is possible to variously control the output for one input within the range of hysteresis.

Therefore, in the brake hydraulic booster system 1 of the first example, the brake assist control can be performed using the hysteresis of the two brake blades 2. The operation of the brake assist control will be described.

When a brake operation is performed by depressing the brake pedal 10, the electronic control unit needs brake assist control based on a pedal depression state such as a rising speed of a pedal stroke (detected by a stroke sensor (not shown)). Is determined, the motor M is driven to operate the first pump 31, and at the same time, the pump discharge liquid supply control valve 57 is operated.
Is opened, the first differential pressure valve 65 is switched to the relief position, and the solenoid valve opening / closing valve 71 is further opened. Then, the discharge pressure of the first pump 31 is changed to the pump discharge liquid supply control valve 57, the solenoid valve opening / closing valve 71, the eleventh check valve 72, and the pressure inlet 6.
9 and the passage hole 68, and is introduced into the power chamber 25,
The hydraulic pressure in the power chamber 25 increases. At this time, due to the hysteresis of the brake hydraulic pressure booster 2, the hydraulic pressure in the power chamber 25 increases within the hysteresis range even with the same pedal depression force.

Since the pump discharge pressure is also introduced into the W / Cs 4, 5 on the driving wheel (front wheel) side, the W / Cs of the W / Cs 4, 5 are obtained.
The pressure increases, but at this time, the pump discharge pressure and the hydraulic pressure in the power chamber 25 become equal, so that the W / C pressure increases at the same pressure as the hydraulic pressure in the power chamber 25. Further, as the hydraulic pressure in the power chamber 25 increases, the output of the power piston 12 also increases, so that the MCY pressure generated by the secondary piston 77 also increases. Since the MCY pressure is introduced into the W / Cs 6, 7 on the non-driven wheels (rear wheels), the W / C pressures of the W / Cs 6, 7 also increase. At this time, each piston 13,76,
77 have the same effective pressure receiving area, so that each W / C
The pressure and the hydraulic pressure in the power chamber 25 rise at the same pressure while being balanced.

During the brake assist control, the stroke of the W / Cs 4, 5 increases due to the increase in the W / C pressure of the W / Cs 4, 5 on the front wheel side. Since the brake fluid is set to the position and the flow of the brake fluid from the first hydraulic chamber 83 to the W / Cs 4, 5 is blocked, the stroke increase of the W / Cs 4, 5 does not affect the pedal stroke. As described above, since the front wheel does not affect the pedal stroke during the brake assist control, an increase in the pedal stroke during the brake assist control can be prevented.

The increase in the stroke of the W / Cs 4, 5 is absorbed by supplying the hydraulic fluid in the power chamber 25 to the W / Cs 4, 5. On the other hand, at the time of the brake assist control, the W / C due to the increase in the W / C pressure of the W / Cs 6, 7 on the rear wheel side is increased.
At this time, the differential pressure valve 66 on the rear wheel side is set to the communicating position, the secondary piston 77 moves forward, and the brake fluid in the second hydraulic chamber 84 becomes W
/ C6,7, the increase in the stroke of W / C6,7 has an effect on the pedal stroke.

According to the first example, the input / output characteristic of the brake hydraulic booster 2 has a hysteresis between the brake operation direction and the brake operation release direction. In this case, the inexpensive twelfth and thirteenth check valves 73, 7 can be used with little change to the conventional brake hydraulic booster and without using expensive solenoid valves.
5, the brake hydraulic booster 2 having hysteresis can be formed easily at low cost.

Further, according to the brake hydraulic pressure boosting system 1, the hysteresis of the brake hydraulic pressure boosting device 2 is used, and the electronic control unit controls the solenoid valve opening / closing valve 71 to the stepping speed or the stepping force of the brake pedal 10. By performing control in accordance therewith, brake assist can be easily and reliably performed.

In addition, the power chamber 25 during the brake assist
ABS control, TRC control, VSC which are already installed as a second hydraulic pressure source for hydraulic pressure introduced into
Since the pump 31 for performing the control and the ACC control is also used, the brake assist function can be provided to the brake hydraulic booster system 1 at a lower cost without increasing the number of parts. . of course,
Although this effect cannot be obtained, it goes without saying that another hydraulic pressure source can be provided as the second hydraulic pressure source.

FIG. 5 is a diagram showing a second example of the embodiment of the present invention. In the following description of the example, the same components as those in the example before the example are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the first example described above, a conventional general conveyor-type brake hydraulic booster 2 in which cup seals 80, 81, and 82 of MCY3 are provided on pistons 76 and 77, respectively, is used. With the power piston 13
And the primary piston 76 are integrally formed. In the brake hydraulic booster system 1 of the second example, as shown in FIG. 5, the MCY3 cup seals 80, 81, and 82 are provided.
Is provided on the housing 11 side, and a plunger type brake hydraulic booster 2 is used, and the power piston 13 and the primary piston 76 are integrally formed.

At the front end of the power piston 13, a primary piston 76 is provided. At the front end of the primary piston 76, a first hydraulic chamber 83 is provided with a reservoir 9.
A radial hole 93 connected to the reservoir 9 through a passage hole 92 of the housing 11 is formed in the housing 11. This radial hole 9
3 is located slightly behind the cup seal 80 in the illustrated non-operating position of the primary piston 76 and communicates the first hydraulic chamber 83 with the reservoir 9, but the primary piston 76 moves forward and ahead of the cup seal 80. , The first hydraulic chamber 83 and the reservoir 9 are not communicated with each other.

On the other hand, the secondary piston 77 of MCY3
Is formed in a bottomed cylindrical shape having an axial hole 94 that opens toward the second hydraulic chamber 84, and the second hydraulic chamber 84 is formed in the reservoir 9 at the front end thereof. A radial hole 96 similar to the radial hole 93 is formed through the passage hole 95. The radial hole 96 is located slightly behind the cup seal 81 at the non-operating position of the secondary piston 77 in the drawing, and connects the second hydraulic chamber 84 to the reservoir 9. When it moves forward and is located forward of the cup seal 81, the second hydraulic chamber 84 and the reservoir 9 are not communicated.

The stepped hole 67 of the housing 11 is formed as a through hole whose both ends are open.
An end (the left end in the figure) of the stepped hole 67 on the MCY3 side is closed by a plug 97 in a liquid-tight manner. As described above, the stepped hole 67 is formed as a through hole, whereby the stepped hole 6 is formed.
7 can be inserted from both ends.

[0068] Further, as shown enlarged in FIG. 6, the small diameter portion 67a of the stepped hole 67 is formed in a different stepped bore of diameter slightly, the inner diameter of MCY3 portion 67a ₂ of the small diameter portion 67a is a power slightly higher than the inner diameter of the piston 13 side portion 67a ₁ has a larger diameter. In accordance with this, the outer diameter of the pressure receiving portion of the primary piston 76 is formed to be slightly larger than the outer diameter of the pressure receiving portion of the power piston 13.

This is for the following reason. That is,
Hydraulic pressure of power chamber 25 and first and second hydraulic chambers 8 of MCY3
When the hydraulic pressures of the pressure pistons 3,84 are the same, the braking force at the time of the brake assist can be easily controlled to a desired level. Therefore, the effective pressure receiving area of the power piston 13 and the MCY3
It is necessary to set the effective pressure receiving areas of both pistons 76 and 77 to be the same. For this reason, the outer diameter of the power piston 13 and the outer diameters of the two pistons 76 and 77 of the MCY 3 may be set to be the same. However, even with this setting, the O-ring 97 that defines the pressure receiving area of the power piston 13 is set. Is provided on the power piston 13, while the cup seal 80,
Since 81 and 82 are provided on the housing 11 side,
The effective pressure receiving area of the power piston 13 and both pistons 76,
77 is slightly different from the effective pressure receiving area. Therefore,
By forming the small diameter portion 67 in the stepped hole in this way,
Each effective pressure receiving area of each piston 3, 76, 77 is set substantially equal.

Further, since the small diameter portion 67a of the stepped hole 67 is formed in the stepped hole, a step 67b is formed in the small diameter portion 67a.
In order to secure a stroke of 6, both pistons 13,7
The length of the small diameter portion 67a of the sliding portion 6 is increased, and a predetermined distance is set between the pistons 13 and 76.

Further, the conical valve 18 'of the control valve 14 and the valve body 1
9 are integrally formed as a single member, the hydraulic pressure discharge passage 27 has a passage hole 27a formed in the conical valve 18 'and the valve body 19, and a collar for slidably supporting the valve body 19. 9
8, a radial hole 27d formed in the power piston 13, an axial groove 27e formed in the outer periphery of the power piston 13, and a passage hole 92. .

Since the hydraulic pressure discharge passage 27 is provided on the conical valve 18 ′ and the valve element 19 side, the reaction force chamber 30 is directly connected to the fifth branch passage 74. Of the fifth branch passage 74,
The portion closer to the reaction chamber 30 than the thirteenth check valve 75 is the sixth
It is connected to a reservoir via a branch passage 99. A twelfth check valve 73 is provided in the sixth branch passage 99.

Further, the input shaft 21 is divided into two parts, a part 21b on the brake pedal 10 connection side and a part 21c on the control valve 14 screwed to the connection side part 21b. This is for the following reason. That is, in order to make the servo ratio of the brake hydraulic booster 2 as high as possible, it is necessary to reduce the pressure receiving area of the input shaft 21 that receives the hydraulic pressure in the power chamber 25. For this purpose, although required to an outer diameter as small as possible of the input shaft 21, since the input shaft 21, it is caulked coupling portion 21b ₁ of the connecting portion 100 connected to the brake pedal 10, the input shaft 2
It is restricted to make 1 a small diameter. Therefore, the input shaft 21 to the two-division structure, while ensuring the caulking portion 21b ₁ by relatively increasing the outer diameter of the brake pedal 10 connected portion 21b, servo to reduce the outer diameter of the control valve 14 side portion 21c The ratio can be easily set to a high servo ratio. In addition, by preparing various portions 21c on the control valve 14 side having different outer diameters and selecting them appropriately, a large degree of freedom in setting the servo ratio can be ensured.

The portion 21c of the input shaft 21 on the control valve 14 side penetrates the plug 12 in a liquid-tight and slidable manner. The liquid tightness between the control valve 14-side portion 21c and the plug 12 is achieved by a double seal structure including two cup seals 101 and 102, whereby external liquid leakage from the reaction force chamber 30 via the input shaft 21 is prevented. It is surely prevented.

Further, the portion 21 of the input shaft 21 on the control valve 14 side
c and the valve actuating member 20 are screwed to each other, and a stepped portion 2 which is the same as the stepped portion 21a of the input shaft 21 described above.
1a is formed. In addition, a cushioning member 103 made of an annular rubber disk or the like is provided on the step 21a. This buffer member 103 is provided with a control valve 14 side portion 21c.
And the valve operating member 20, so that the contact noise when the reaction force piston 23 contacts the stepped portion 21a is reduced. Other configurations of the brake hydraulic booster system 1 of the second example are the same as those of the above-described first example.

In the brake hydraulic booster system 1 of the second example configured as described above, when the brake operation is performed by depressing the brake pedal 10, the input shaft 21 moves forward as described above. At this time, the volume of the reaction force chamber 30 increases, and the pressure of the reaction force chamber 30 tends to decrease to a negative pressure. However, the brake fluid flows from the reservoir 9 to the sixth branch passage 99 and the first
Since the pressure is introduced into the reaction chamber 30 through the two check valves 73, the pressure drop in the reaction chamber 30 is compensated, and the input shaft 21 advances smoothly.

When the depression of the brake pedal 10 is released to release the brake operation, the input shaft 21 attempts to move backward. At this time, the hydraulic pressure in the power chamber 25 is
Since the rear end 23c is at a pressure that keeps the rear end 23c of the input shaft 21 in contact with the stepped portion 21a of the input shaft 21, the reaction force piston 23 also tries to retreat with the retraction of the input shaft 21. For this reason, the pressure of the reaction force chamber 30 increases. When this pressure becomes higher than the W / C pressure of W / C 4,5, the thirteenth
The check valve 75 is opened, and the liquid in the reaction force chamber 30 is
To the first branch passage 33a, that is, to the W / C4, 5 side. Therefore, the pressure in the reaction force chamber 30 is reduced under the same pressure as the W / C pressure.

The pressure reduction of the reaction force chamber 30 causes the input shaft 21
And the reaction force piston 23 are retracted together, and the valve operating member 2
Moves away from the conical valve 18 '. Then, the pressurized liquid in the power chamber 25 flows into the gap between the conical valve 18 ′ and the valve operating member 20 and the passage hole 2.
7a, radial hole 27b, annular groove 27c, radial hole 27
d, is discharged to the reservoir 9 through the axial groove 27e and the passage hole 92. As a result, the pressure in the power chamber 25 decreases, and the power piston 13 retreats.

At this time, the pressure of the reaction force chamber 30 is opposed to the hydraulic pressure of the power chamber 25 acting on the reaction force piston 23 at the rear end 23c of the reaction force piston 23 (in the same direction as the input of the input shaft 21). ), The brake hydraulic booster 2
Is substantially the same as the state in which the rear end 23c of the reaction force piston 23 does not contact the step portion 21a of the input shaft 21, and the servo ratio becomes substantially the same as the servo ratio at the time of the jumping characteristic.

The brake hydraulic booster system 1 of the second example
In this case as well, the input / output characteristics of the brake hydraulic booster 1 are almost the same as the input / output characteristics shown in FIG. 4 and have a large hysteresis. Other operational effects of the brake hydraulic booster system 1 of the second example are the same as those of the first example.

FIG. 7 is a diagram showing a third example of the embodiment of the present invention. As shown in FIG. 7, the brake hydraulic booster system 1 of the third example is the same as the second embodiment shown in FIGS.
It has a brake hydraulic booster 2 in which a plunger-type MCY 3 similar to the example is integrated. MCY3 of the third example
Is different from the tandem type MCY of the second example in that the single type M
CY. In the third example, the passage hole 68 communicating with the power chamber 25 of the brake hydraulic booster 2 is connected to the first passage 33 of one system. That is,
A power chamber 25 is directly connected to one of the WCYs 4 and 5.

On the other hand, a first hydraulic chamber (hereinafter simply referred to as a hydraulic chamber in this example) 83 of the MCY 3 is connected to the second passage 33 of the other system. That is, the hydraulic chamber 8 of the MCY3
3 is directly connected to WCY6, 7 of the other system.

As described above, in the brake hydraulic pressure boosting system 1 of this example, one system is a full power brake in which the hydraulic pressure of the power chamber 25 is introduced, and the other system is the hydraulic system of the MCY3. MCY pressure brake.

Further, the discharge passage 27 is provided on the valve operating member 20 and the input shaft 21 side, and the twelfth check valve 73 is disposed in the discharge passage 27, just like in the first embodiment. A thirteenth check valve 74 is provided in a fifth branch passage 74 from the discharge passage 27.

Further, the input shaft 21 has a non-divided structure as in the first example, and the seal between the plug 12 and the sliding portion of the input shaft 21 is single. Other configurations of the brake hydraulic booster 1 of the third example are the same as those of the second example.

In the brake hydraulic booster system 1 of the third example configured as described above, the pressure receiving area of the power piston 13 by the O-ring 97 and the M
Since the pressure receiving area of the CY piston 76 is set equal, the WCY pressures of all the WCYs 4, 5, 6, and 7 become equal. Other functions and effects of the brake hydraulic booster system 1 of the third example are the same as those of the second example.

FIG. 8 is a diagram showing a fourth example of the embodiment of the present invention. In the third example shown in FIG. 7, the MCY3 is constituted by a single MCY, but in the brake hydraulic booster system 1 of the fourth example, the MCY3 is constituted by a tandem MCY as shown in FIG. In that case, the second hydraulic chamber 84 is connected to the second passage 34 of the other system. Although not shown, the first hydraulic chamber 83 of the MCY 3 is connected to, for example, a stroke simulator to adjust the stroke of the brake pedal 10 and the hydraulic pressure source (the pump 31, the accumulator 32, and the like) of the brake hydraulic booster 2. It can be used for other purposes such as an emergency hydraulic chamber when a failure occurs. Other configurations and other operational effects of the brake hydraulic booster system 1 of the fourth example are the same as those of the third example.

FIG. 9 is a diagram showing a fifth example of the embodiment of the present invention. In the third example shown in FIG.
3 and the primary piston 76 of the MCY 3 are integrally formed, but in the brake hydraulic booster system 1 of the fifth example, the power piston 13 and the primary piston 76 are formed separately as shown in FIG. Have been. These pistons 13 and 76 have their maximum intervals regulated by the interval regulating means 78 similar to the first example shown in FIG. 2, and are set to the illustrated maximum intervals when not actuated by the spring 79. .

A hydraulic chamber 104 is formed between the power piston 13 and the primary piston 76. The hydraulic chamber 104 is hermetically sealed so that the pistons 13 and 76 are integrally connected to each other, or the stroke of the brake pedal 10 can be adjusted as in the fourth embodiment.
It can be used for other purposes such as an emergency hydraulic chamber. Fifth example brake hydraulic booster system 1
Other configurations and other effects are the same as those of the third example.

[0090]

As is apparent from the above description, according to the hydraulic booster according to the first to third aspects of the present invention, the input / output characteristics of the hydraulic booster are mechanically dependent on the operation direction and the operation release direction. Can have hysteresis.
In that case, the reaction force piston and reaction force chamber conventionally provided for the jumping characteristic can be used as they are, so that the conventional hydraulic booster has hysteresis easily and inexpensively with almost no design change. A hydraulic booster can be formed. According to the third aspect of the present invention, it is possible to suppress the contact noise when the reaction force piston comes into contact with the step portion of the input shaft.

Further, according to the brake hydraulic boosting system of the inventions of claims 4 to 8, the braking force is required when the brake assist is required by the hysteresis characteristic of the hydraulic booster and the hydraulic pressure of the second hydraulic pressure source. Can be bigger. In this case, the magnitude of the braking force for the same input can be variously controlled within the range of the hysteresis of the input / output characteristics of the hydraulic booster.

In this case, since only inexpensive first and second check valves are used without using expensive solenoid valves, a brake hydraulic booster having hysteresis can be formed inexpensively and easily. can do. In particular, according to the invention of claim 7, when brake assist is required at the time of sudden braking or the like, the brake assist can be easily and reliably performed. According to the eighth aspect of the present invention, ABS control, TRC control, VSC control, and ACC control which are already mounted as a second hydraulic pressure source for hydraulic pressure introduced into the power chamber at the time of brake assist. , The brake hydraulic booster system 1 having the brake assist function can be formed more inexpensively without increasing the number of parts.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first example of an embodiment of a brake hydraulic booster system according to the present invention.

FIG. 2 is a sectional view showing an example of a brake hydraulic booster used in the first example shown in FIG.

3 is a partially enlarged sectional view showing a part of the brake hydraulic booster shown in FIG. 2 in an enlarged manner.

FIG. 4 is a diagram showing input / output characteristics of the brake hydraulic booster shown in FIG. 2 having hysteresis.

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

6 is a partially enlarged cross-sectional view showing a part of the brake hydraulic booster used in the second example shown in FIG. 5 in an enlarged manner.

FIG. 7 is a diagram showing a third example of the embodiment of the present invention.

FIG. 8 is a diagram showing a fourth example of the embodiment of the present invention.

FIG. 9 is a diagram showing a fifth example of the embodiment of the present invention.

FIG. 10 is a diagram showing a conventional brake hydraulic booster system.

11 is a sectional view showing an example of a brake hydraulic booster used in the conventional example shown in FIG.

FIG. 12 is a diagram showing input / output characteristics of the conventional brake hydraulic booster shown in FIG. 11 without hysteresis.

[Explanation of symbols]

1: Brake hydraulic booster, 2: Brake hydraulic booster, 3: Master cylinder (MCY), 4, 5, 6, 7, ...
Wheel cylinder (WCY), 8 ... ABS control, TRC
Control system, VSC control, and ACC control, two systems of brake pressure control devices, 9 reservoir, 10 brake pedal, 11 housing, 12 plug, 13 power piston, 14 control valve, 21 input shaft, 21a ... Step portion of input shaft 21, 23 ... reaction force piston, 23c ... rear end of reaction force piston 23, 25 ... power chamber, 27 ... hydraulic pressure discharge passage, 2
8 output shaft, 30 reaction chamber, 31 pump, 32 accumulator, 33 first passage, 34 second passage, 68
Passage hole, 69: pressure inlet, 71: solenoid on-off valve, 73 ...
12th check valve, 74 ... fifth branch passage, 75 ... 13th check valve, 76 ... primary piston, 77
... secondary piston, 80, 81, 82 ... cup seal, 83 ... first hydraulic chamber, 84 ... first hydraulic chamber, 103 ... buffer member

Continued on the front page (72) Inventor Masahiro Shimada 2-11-6 Shinmeicho, Higashimatsuyama-shi, Saitama Automobile Equipment Co., Ltd. Matsuyama Plant (72) Inventor Satoru Watanabe 2-11-6 Shinmeicho, Higashimatsuyama-shi, Saitama Automotive Equipment Co., Ltd. Matsuyama Plant (72) Inventor Junichi Hirayama 2--11-6 Shinmeicho, Higashimatsuyama City, Saitama Prefecture Automotive Equipment Co., Ltd. Matsuyama Plant (72) Inventor Sawada Mamoru 1-chome, Showacho, Kariya City, Aichi Prefecture No. 1 Inside Denso Corporation

Claims (8)

[Claims] 1. A hydraulic pressure source for generating hydraulic pressure, a reservoir for storing hydraulic fluid, a power piston for generating an output, a power chamber facing a pressure receiving surface of the power piston, and a power chamber when not operating. A control for shutting off the hydraulic pressure source and communicating with the reservoir, shutting off the power chamber from the reservoir during operation and communicating with the hydraulic pressure source, and introducing the hydraulic fluid of the hydraulic pressure source into the power chamber. A stepped valve having a small-diameter portion on the control-valve side and a large-diameter portion on the side opposite to the control-valve side, the valve being advanced when activated and retracted when deactivated to operate the control valve. The input shaft, the outer diameter is set to be larger than the diameter of the portion of the input shaft on the side opposite to the control valve side, is formed in a cylindrical shape, and is slidably fitted to the small diameter portion of the input shaft, The front end faces the power chamber and the rear end A reaction force piston capable of contacting a step portion of the force shaft, wherein a reaction force chamber is formed so that the step portion of the input shaft is located, and the reaction force chamber is provided in the reaction force chamber when the input shaft advances. And a pressure control means for introducing different pressures when the input shaft is retracted. 2. The pressure introduced into the reaction chamber when the input shaft is advanced is atmospheric pressure, and the pressure introduced into the reaction chamber when the input shaft is retracted depends on the output of the power piston. The hydraulic booster according to claim 1, wherein the hydraulic booster is a pressure. 3. The hydraulic booster according to claim 1, wherein a buffer member is provided at a step portion of the input shaft or at a rear end of the reaction force piston. 4. A hydraulic booster according to claim 2 or 3, a master cylinder having a master cylinder piston for generating a master cylinder pressure by an output of the hydraulic booster, and wherein the master cylinder pressure is introduced. And a second hydraulic pressure source for generating hydraulic pressure, and the hydraulic pressure from the second hydraulic pressure source during operation is supplied to the power chamber without passing through the control valve. A hydraulic pressure supply valve comprising an electromagnetic valve to be introduced, and an electronic control device for controlling the operation of the hydraulic pressure supply valve when necessary, wherein the pressure control means connects the reaction chamber to the reservoir. A first check valve provided in the passage and allowing only the flow of the hydraulic fluid from the reservoir to the reaction chamber; and a first check valve provided in the passage connecting the reaction chamber to the brake cylinder. Brake boosting system characterized by comprising a second check valve which allows only the flow of hydraulic fluid toward the brake cylinder from the reaction chamber. 5. A hydraulic pressure discharge passage for discharging the hydraulic fluid in the power chamber to the reservoir is connected to the reaction chamber, and the hydraulic fluid in the power chamber is supplied to the reaction chamber and the second check. The brake hydraulic booster system according to claim 4, wherein the hydraulic fluid of the valve and the brake cylinder is discharged to the reservoir via a passage that is discharged to the reservoir. 6. The brake hydraulic boosting system according to claim 4, wherein an effective pressure receiving area of the power piston and an effective pressure receiving area of the master cylinder piston are set to be equal. 7. The hydraulic control valve according to claim 4, wherein the electronic control unit controls the hydraulic pressure supply valve according to an operation speed or an operation force of an operation member for operating the input shaft.
7. The brake hydraulic booster system according to any one of claims 6 to 6. 8. The vehicle according to claim 1, further comprising at least one of an anti-lock control system, a traction control system, a cornering attitude control system and an auto cruise control system, wherein said second hydraulic pressure source is also used as a hydraulic pressure source of said control system. The brake hydraulic booster system according to any one of claims 4 to 7, wherein: