JP2000108883A - Automatic brake booster - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the operation responsiveness of braking during normal braking and to smoothly control an output during automatic braking. SOLUTION: A sleeve 18 constituting a valve mechanism 15 is provided with a driving part 50, a valve seat part 51 having a second valve seat 19, an engaging part 52 engaged with the valve seat when the driving part advances, and a conical spring 53 separating the driving part and the valve seat part from each other. The conical spring is compressed during normal braking to expand the valve opening amount of the second valve seat compared with that during automatic braking. A plate plunger 40 for transmitting a brake resisting force is provided with first and second members 71 and 72 to be displaced relative to each other, a brake resisting force applied on both members is transmitted to a valve plunger during normal braking, and only the brake resisting force of the first member is transmitted to the sleeve during automatic braking.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic brake booster used for a brake of an automobile or the like.
It relates to improvement of the valve mechanism.

[0002]

2. Description of the Related Art Conventionally, as an automatic brake booster, a valve body slidably provided in a shell, a power piston provided in the valve body, a constant pressure chamber and a variable pressure chamber formed before and after the power piston. A valve mechanism provided in the valve body, an input shaft for switching a flow path of the valve mechanism by moving a valve plunger that constitutes the valve mechanism forward and backward,
An output shaft slidably provided on the valve body; a reaction disk and a plate plunger interposed between a base of the output shaft and the valve plunger; A valve seat, a sleeve slidably fitted in the valve body, a second valve seat formed in the sleeve, a valve element seated on the first valve seat and the second valve seat, and the sleeve A drive means for displacing the valve to the front side to switch the flow path, and further provided to the valve body and the sleeve so as to be relatively displaceable and interlocked with the input shaft, and displaces the sleeve to the front side when the input shaft advances. There is known a device provided with the valve plunger for switching the flow path. By the way, a conventional general automatic brake booster uses a solenoid as a driving means.

[0003]

However, in the above-mentioned solenoid, in order to obtain a large magnetic force, the solenoid itself must be enlarged.
The difference between the magnetic force of the solenoid and the biasing force of the biasing spring is reduced, and the difference between the biasing force of the biasing spring and the biasing force of biasing the sleeve toward the front side is reduced, thereby reducing the size and weight of the solenoid. Had been planned. The biasing force for biasing the sleeve to the front side includes a differential pressure acting on the sleeve and a valve body seated on the second valve seat formed on the sleeve, and a poppet return spring for biasing the valve body to the front side. There is. Also, since the thrust acting on the sleeve becomes larger as the solenoid gap becomes smaller, the solenoid gap is conventionally required so as to obtain sufficient operation response during automatic braking in consideration of the magnetic force of a small solenoid. Was set small. However, if the solenoid gap is set to be small, the opening amount of the second valve seat becomes small, so that the opening amount of the second valve seat is the same during normal braking and during automatic braking. It has been pointed out that the conventional automatic brake booster had poor operation responsiveness during sudden braking during normal braking. Further, in the conventional automatic brake booster, since the brake reaction force is configured not to be transmitted to the sleeve, even if an attempt is made to adjust the valve opening amount of the second valve seat by changing the magnetic force of the solenoid, as described above, Since the difference between the magnetic force of the solenoid and the biasing spring is small, even if the magnetic force of the solenoid is reduced, the opening amount of the second valve seat is immediately fully opened, and the brake output cannot be controlled. As a result, there is a disadvantage that the brake output becomes excessive in a relatively low speed range. In order to solve the above-described problem, it is conceivable to transmit the brake reaction force by bringing the sleeve into contact with the plate plunger. However, in such a configuration, the brake reaction force transmitted from the plate plunger causes the magnetic force of the solenoid (sleeve Is too large with respect to the thrust), there is a disadvantage that the opening amount of the second valve seat becomes small, the brake output becomes insufficient, and the operation responsiveness deteriorates. In view of the above circumstances, the present invention can improve the operation responsiveness at the time of sudden braking during normal braking without impairing the operation responsiveness at the time of automatic braking. An object of the present invention is to provide an automatic brake booster capable of controlling output.

[0004]

According to a first aspect of the present invention, there is provided a valve body slidably provided in a shell, a power piston provided in the valve body, and a constant pressure chamber formed before and after the power piston. And a variable pressure chamber, and a valve mechanism provided in the valve body for performing switching control of the flow path. The valve mechanism is slidably fitted in a first valve seat formed in the valve body and in the valve body. A combined sleeve, a second valve seat formed in the sleeve, a valve body seated on the first valve seat and the second valve seat, and displacing the sleeve to the front side to switch the flow path. A drive means, and a valve plug which is provided in the valve body and the sleeve so as to be relatively displaceable and is interlocked with the input shaft, and displaces the sleeve to the front side when the input shaft advances to switch the flow path. In automatic brake booster and a Nja, the sleeve, a drive unit which is displaced to the front side by the driving means, the conjunction is displaced to the front side by the valve plunger second
A valve seat portion forming a valve seat, an engaging portion that engages with the valve seat portion when the driving portion is displaced to the front side and displaces the valve seat portion to the front side, and the driving portion and the valve seat portion. And a resilient member that is disposed between the two and separates the two members. The resilient member holds the drive unit and the valve seat in a separated state when the drive unit is displaced to the front side by the drive unit. When the valve plunger is displaced to the front side by the valve plunger, the valve is compressed to bring the drive unit and the valve seat close to each other to increase the valve opening amount of the second valve seat.

According to a second aspect of the present invention, there is provided a valve body slidably provided in a shell, a power piston provided in the valve body, a constant pressure chamber and a variable pressure chamber formed before and after the power piston. A valve mechanism provided in the valve body for controlling switching of the flow path, the valve mechanism comprising: a first valve seat formed in the valve body; a sleeve slidably fitted in the valve body; A second valve seat formed on the sleeve, a valve body seated on the first valve seat and the second valve seat, a driving means for displacing the sleeve to the front side to switch the flow path, A valve plunger which is provided in the valve body and the sleeve so as to be relatively displaceable and is interlocked with the input shaft, and displaces the sleeve toward the front side when the input shaft is advanced to switch the flow path. The automatic brake booster, the elastic member is disposed with a predetermined space between the front side and the valve body of the sleeve, said elastic member,
When the sleeve is displaced to the front side by the driving means, the sleeve is prevented from being displaced to the front side without being substantially compressed, and when the sleeve is displaced to the front side by the valve plunger, the second valve is compressed. It is characterized in that the amount of valve opening of the seat is increased.

According to a third aspect of the present invention, in the automatic brake booster having the same configuration as the above-described conventional automatic brake booster, the plate plungers are provided so as to be able to approach and separate in the axial direction, and are mutually movable. A first member and a second member that come into contact with the reaction disk, and the first member engages with the second member during normal braking to act on the brake reaction force acting on the second member and on itself. The brake reaction force is transmitted to the valve plunger, and at the time of automatic braking, the brake reaction force acting on itself is separated from the second member abutting on the valve body and transmitted to the sleeve.

According to a sixth aspect of the present invention, in the automatic brake booster having the same structure as the above-mentioned conventional automatic brake booster, the first member abuts on the sleeve during normal braking and is itself. The brake reaction force acting on the valve plunger is transmitted to the valve plunger via the sleeve, and at the time of automatic braking, its own brake reaction force is transmitted to the sleeve separated from the valve plunger. A brake reaction force acting on the plunger and acting on itself is transmitted to the valve plunger, and a brake reaction force acting on itself and coming into contact with the valve body during automatic braking is transmitted to the valve body. It is.

According to a seventh aspect of the present invention, in the automatic brake booster having the same configuration as the above-mentioned conventional automatic brake booster, the plate plunger is provided so as to be relatively displaceable in the axial direction. A first member and a second member that mutually contact the reaction disc, and the first member transmits a brake reaction force acting on itself to the valve plunger during normal braking by contacting the valve plunger; During automatic braking, the second member transmits its own brake reaction force to the sleeve separated from the valve plunger, and during normal braking, the second member transmits the valve reaction force acting on itself by abutting on the valve plunger. At the same time, during automatic braking, the valve body applies a brake reaction force acting on It is characterized in that transmitted to.

[0009]

According to the first aspect of the present invention, the amount of opening of the second valve seat during automatic braking is reduced by the elastic member provided between the driving portion and the valve seat portion, while during normal braking, Since the amount of opening of the second valve seat can be increased, even if the amount of opening of the second valve seat is set to be large in order to improve the operation responsiveness during sudden braking during normal braking, automatic Since the opening amount of the second valve seat at the time of braking is small, it is possible to improve the operation responsiveness at the time of sudden braking at the time of normal braking without impairing the operation responsiveness at the time of automatic braking.

According to the second aspect of the present invention, the amount of opening of the second valve seat during automatic braking is reduced by the elastic member provided between the sleeve and the valve body, while the second valve during normal braking. Since the amount of opening of the seat can be increased, even if the amount of opening of the second valve seat is set to be large to improve the operation responsiveness during sudden braking during normal braking, Since the opening amount of the second valve seat is small, it is possible to improve the operation responsiveness at the time of sudden braking during normal braking without impairing the operation responsiveness at the time of automatic braking.

According to the third, sixth, and seventh aspects of the present invention, the brake reaction force acting on the first member and the second member at the time of normal braking is applied to the driver via the valve plunger and the input shaft. Therefore, the brake output can be controlled in the same manner as a conventional general brake booster. On the other hand, at the time of automatic braking, the brake reaction force acting only on the first member is transmitted to the solenoid. Therefore, even if the solenoid has a small magnetic force, the second valve is opposed to the brake reaction force by changing the magnetic force. Since the amount of opening of the seat can be adjusted, the brake output during automatic braking can be smoothly controlled.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiment. In FIG. 1, a shell 2 of a tandem brake booster 1 defines a front chamber 4 and a rear chamber 5 in front and rear by a center plate 3. . Then, a cylindrical valve body 6 is slidably penetrated through the rear side of the shell 2 and the center plate 3 while maintaining airtightness by sealing means 7 and 8, respectively. Front power piston 10 and rear power piston 1 are provided on the outer peripheral portions of valve body 6 located in front chamber 4 and rear chamber 5, respectively.
1 and each power piston 10, 11
A front diaphragm 12 and a rear diaphragm 13 are respectively stretched on the back of the vehicle. And the front room 4
A constant-pressure chamber A before and after the front diaphragm 12
A constant pressure chamber C and a variable pressure chamber D are formed before and after the rear diaphragm 13 in the rear chamber 5. In the valve body 6, a valve mechanism 1 for switching a communication state between the constant pressure chambers A and C and the variable pressure chambers B and D.
5 are provided.

The valve mechanism 15 is slidably fitted in the valve body 6 with a first valve seat 17 formed at the tip of a large-diameter annular projection 16 extending rearward from the inner peripheral portion of the valve body 6. Sleeve 18, a second valve seat 19 formed on the sleeve 18, and a first seat portion S1 and a second valve which are urged to the front side by a poppet return spring 20 to be seated on the first valve seat 17. The valve body 21 having the second seat portion S2 seated on the seat 19, and the sleeve 18 are urged rearward so that the second valve seat 19 is moved relative to the first valve seat 17.
Spring 22 for holding the spring in the forward position, and this spring 2
And a valve plunger 25 provided in the valve body 6 and the sleeve 18 so as to be relatively displaceable and interlocked with the input shaft 24. I have. Further, the valve mechanism 15 includes an axial constant-pressure passage 26 formed in the valve body 6 for communicating a space outside the first valve seat 17 with the constant-pressure chamber A, and the constant-pressure passage 26 and the constant-pressure chamber C. And a space between the second valve seat 19 and the first valve seat 17 in the radial direction constant pressure passage 27 for communicating
And the constant-pressure chamber B
And a variable-pressure chamber 29 communicating with the variable-pressure chamber D in the axial direction, and an air passage 30 formed in the end cylindrical portion 6A that communicates a space inside the second valve seat 19 with the atmosphere. In addition, a filter 31 is provided in the air passage 30. The constant-pressure chamber A is connected to an intake manifold of the engine via a negative-pressure introducing pipe (not shown) provided in the shell 2, whereby negative pressure is constantly introduced into the constant-pressure chambers A and C. An annular seal ring 3 is provided around the outer periphery of the valve plunger 25 in which the sleeve 18 is fitted.
2 and the sleeve 18 is
Of the valve plunger 25 is kept airtight. The solenoid 23 is sandwiched between a yoke 34 and a holder 35 fitted in the valve body 6, and is connected to an external control device (not shown) via a wiring 36 disposed along the inner wall of the shell 2. ing.

The right end of the valve plunger 25 is connected to the left end of an input shaft 24, and the right end of the input shaft 24 is connected to a brake pedal (not shown). On the left side of the valve plunger 25, a plate plunger 40 and a reaction disk 41 fitted in the large-diameter portion 35a of the holder 35 are sequentially arranged, and an output shaft 42 is provided on the left end surface of the reaction disk 41. Abuts the base. The output shaft 42 has its base at the holder 35.
On the other hand, the front end portion is made to protrude outside from the shaft portion of the shell 2 via the seal member 43.
Further, a valve return spring 46 is elastically mounted on a retainer 44 fixed in the end cylindrical portion 6A of the valve body 6 and a retainer 45 fitted on the input shaft 24.
The input shaft 24, the valve plunger 25, the sleeve 18, and the valve body 21 connected to the input shaft 24 are urged rearward by the elastic force of the valve return spring 46. Further, the valve plunger 25 is prevented from being pulled out of the valve body 6 by a conventional well-known key member 47, and this key member 47 is brought into contact with the rear inner surface of the shell 2 when the booster is not operated. The valve plunger 25 to the valve body 6
In the forward position with respect to. Then, a return spring 48 is elastically mounted between the front inner wall of the shell 2 and the valve body 6, and the valve body 6 is normally held at a non-operating position in the drawing. In this embodiment, as will be described in detail later, the sleeve 18 is displaced to the front side by the solenoid 23 as shown in FIG. A valve seat portion 51 formed with the valve seat 19, an engaging portion 52 that engages with the valve seat portion 51 when the driving portion 50 is displaced to the front side and displaces the valve seat portion 51 to the front side; A disc spring 53 as an elastic member disposed between the valve seat 50 and the valve seat 51 reduces the valve opening amount of the second valve seat 19 during automatic braking by the solenoid 23, and reduces the valve opening during normal braking. The opening amount of the two-valve seat 19 is increased to improve the operation responsiveness at the time of sudden braking during normal braking without impairing the operation responsiveness at the time of automatic braking.
In this embodiment, as will be described in detail later, the effective diameter of the rolling portion 60 of the valve element 21 and the effective diameter of the seal member 32 are set to be the same, and the effective diameter of the second valve seat 19 is set to the effective diameter. By setting the same as or smaller than the above, the solenoid 23 having a smaller magnetic force than the conventional one can be used. Further, in the present embodiment, the plate plunger 40 is formed of a first member 71 and a second member 72 which are provided so as to be relatively displaceable and mutually contact the reaction disk 41, as will be described in detail later.
By configuring a part of the brake reaction force acting on the first member 71 to be transmitted to the sleeve 18, the brake output during automatic braking can be controlled without impairing the operability during normal braking. It is made possible.

That is, the sleeve 18 of the present embodiment is
As shown in the enlarged view of FIG.
A drive unit 50 made of a magnetic material penetrated through A, and a nonmagnetic material fitted to the main body 25B of the valve plunger 25 and having a rear end protruding more rearward than the first valve seat 17. A valve seat 51 and a distal end which is penetrated through the valve seat 51 from the front side and whose tip is press-fitted into the driving unit 50 and bent outward in the radial direction are formed as step portions in the valve seat 51. It is composed of an engaging portion 52 that engages with the end face, and a disc spring 53 penetrated by the engaging portion 52 and disposed between the driving portion 50 and the valve seat portion 51, as shown in FIG. In the non-operating state, the driving portion 50 and the valve seat portion 51 are separated from each other by the disc spring 53, and the valve seat portion 51 is engaged with the end of the engaging portion 52.
The valve seat portion 51 is fitted to the valve plunger 25 from the front side, and the front-side cylindrical portion 5 whose front-end flange portion 54A engages with the flange portion 25C of the valve plunger 25.
4 and a rear side cylindrical portion 55 which is fitted to the valve plunger 25 from the rear side and whose end is connected to the flange portion 54A of the front side cylindrical portion 54 and which is located on the rear side of the first valve seat 17. The rear-side cylindrical portion 55 is formed to have the same diameter as the annular protrusion 16 and has a distal end bent inward in the radial direction. A second valve seat 19 having the same diameter as the first valve seat 17 is formed. The urging spring 22 is elastically mounted between the rear surface of the rear side cylinder portion 55 and the step portion of the valve plunger 25,
Normally, the sleeve 54 is brought into contact with the flange portion 54A of the front cylinder portion 54 by contact with the flange portion 25C of the valve plunger 25.
8 is held in an advanced position with respect to the valve plunger 25. By the way, the holder 35 is inserted into the yoke 34 without any gap in the radial direction, and the valve plunger 25 has its small diameter portion 25A on the inner peripheral projection 35d of the holder 35 and the main body 25B on the rear end inner peripheral portion 34a of the yoke 34. The driving unit 50 is slidably supported, and the driving unit 50 is slidably supported on the inner periphery of the holder 35 and the outer periphery of the main body unit on the inner periphery of the yoke 34. Further, the valve seat portion 51 is slidably supported on the intermediate portion 25d of the valve plunger 25 and the outer periphery of the flange portion 25C. On the other hand, the outer circumference of the valve plunger 25 and the inner circumference of the drive unit 50, the inner circumference of the valve seat 51 and the yoke 34,
The outer periphery of the engagement portion 52 and the inner periphery of the valve seat portion 51 each have a gap in the radial direction. Thereby, the valve plunger 25
The drive unit 50 and the valve seat 51 can be relatively displaced smoothly without sticking to each other.

Next, the first valve seat 17 and the second valve seat 1 of the present embodiment will be described.
9 are arranged in series in the axial direction as described above, and have the same effective diameter. Specifically, the second valve seat 19 is enlarged in diameter and the first valve seat 17 is enlarged. The two valve seats 17 and 19 are set to be the same without reducing the diameter. On the other hand, the valve body 21 seated on the first valve seat 17 and the second valve seat 19 arranged in series in the axial direction has its base fitted to the inner peripheral surface of the valve body 6 and into the valve body 6. A rolling portion 60 made of an elastic material sandwiched by the outer peripheral surface of the retainer 44, a backup plate 61 connected to the front end of the rolling portion 60, and the end thereof on the outer periphery of the backup plate 61. While being caulked,
A metal tubular portion 62 surrounding the second valve seat 19 and extending to the front side, and a backup plate 63 connected to the tip of the tubular portion 62 and bent inward in the radial direction are provided. The second seat portion S2 is formed by a seat portion 64 provided on the front end surface of one backup plate 61, and the first seat portion S1 is formed by a seat portion 65 provided on the front end surface of the other backup plate 63. Make up. Then, these first sheet portions S
The distance between the first valve seat 17 and the second seat portion S2 is
The distance from the valve seat 19 is set slightly larger. Thus, in the non-operating state shown in the drawing, the second seat portion S2 is seated on the second valve seat 19, while the first seat portion S1 is in the first valve seat 1
7, the negative pressure is introduced into the transformation chamber B, and the transformation chamber A and the transformation chamber B have the same pressure. In this state, the sleeve 18 and the valve body 21 are attached to the valve plunger 25.
And the resiliency of the poppet return spring 20 for urging the valve element 21 toward the front side. Then, as shown in FIG. 3, the effective diameter D1 of the rolling portion 60 and the effective diameter D3 of the seal member 32, which are turned outward in the radial direction, and the effective diameter D2 of the second valve seat 19 are each set to a predetermined effective diameter D. And the effective diameters D1, D
2 and D3 are set identically. Note that the effective diameter of the seal member 32 is substantially the same as the inner diameter of the sleeve 18.

Furthermore, the plate plunger 40 of the present embodiment
2, a cylindrical first member 71 slidably fitted in a small diameter portion 35b in a holder 35 forming a part of the valve body 6, and a medium diameter portion 35c in the holder 35. And a ring-shaped second member 72 slidably fitted therein, and an opening 7 formed at a center position of the second member 72.
A small-diameter portion 71A formed at the center of the first member 71 is protruded toward the front side via the second member 2a, and the concentrically arranged small-diameter portion 71A and the second member 72 are coupled to the reaction disk 4.
1 is configured to be able to contact the rear end surface. When the booster is not operating, the second member 72 is engaged with the step of the first member 71 and is separated from the holder 35. In this state, a predetermined gap A is formed between the second member 72 and the holder 35. ing. The drive portion 50 of the solenoid 23 is integrally provided with a thin cylindrical portion 73 extending slidably between the small diameter portion 35a of the holder 35 and the valve plunger 25 and extending in the axial front side. And this cylindrical part 7
When the booster is not operated, 3 is separated from the first member 71, and a predetermined gap B is formed between the cylindrical portion 73 and the first member 71. When the booster is not operated, the drive unit 50 is stopped at a position retracted rearward from the holder 35 by a predetermined distance, and the distance is determined by the first valve seat 17.
C of the first seat portion S1 of the valve element 21 which is separated from the valve body 21
It is formed slightly larger than that. In this embodiment, in order to increase the servo ratio of the automatic brake, the values of each of the intervals A, B, and C are set so as to satisfy the expression of interval A <(interval B−interval C). I have.

According to the present embodiment configured as described above,
When the second seat portion S2 of the valve body 21 is seated on the second valve seat 19 formed on the sleeve 18, while the first seat portion S1 is separated from the first valve seat 17 of the valve body 6 at the time of non-operation. In the above, a differential pressure urged toward the front side acts on a portion located on the inner side of the effective diameter D on the rolling portion 60. At this time, the tip of the rolling portion 60 is connected. On the rear side backup plate 61, a differential pressure urging the rear side acts on a portion located on the inner side of the effective diameter D, whereby the rolling portion 60 is attached to the front side. The energized differential pressure is thereby canceled, and the valve element 21 is not energized by the differential pressure. On the other hand, the sleeve 18
Conventionally, the rear end face located on the outer side of the effective diameter D2 of the seal member 32 faces the negative pressure, while the front end face faces the atmosphere. However, in this embodiment, since the rear end face and the front end face both face negative pressure, the sleeve 18 is not urged by the differential pressure. On the other hand, the first valve seat 17 formed in the valve body 6
When the first seat portion S1 is seated and the second seat portion S2 is separated from the second valve seat 19 formed on the sleeve 18, the first valve seat 17 has the same diameter as the second valve seat 19. , The valve element 21 is not urged by the differential pressure even during the operation as in the non-operation. In contrast to this embodiment, in the conventional valve mechanism, the effective diameter of the second valve seat is set to be larger than the effective diameter of the seal member, and the rolling portion of the valve element is larger than the effective diameter of the second valve seat. When the booster in which the valve element is seated on the second valve seat and the valve element is separated from the first valve seat is not operated, the effective diameter of the booster is set to be large. Differential pressure was acting on the valve body seated on the two valve seats. For this reason, since the biasing force of the biasing spring is set in consideration of the differential pressure and the biasing force of the poppet return spring, it was difficult to reduce the magnetic force of the solenoid. Since the sleeve 18 and the valve element 21 are not both biased by the differential pressure, the biasing force of the biasing spring 22 can be set by taking only the poppet return spring 20 into consideration. (There is a sliding resistance between the sleeve 18 and the valve member 25 or a sliding resistance between the sleeve 18 and the seal member 32), whereby the solenoid 23 which is smaller, lighter and cheaper than the conventional one can be used. In the above embodiment, the effective diameter D1 of the rolling portion 60, the effective diameter D3 of the seal member 32, and the effective diameter D2 of the second valve seat 19 are set to be the same, but the present invention is not limited to this. Without changing the effective diameter D2 of the second valve seat 19 to the other effective diameters D1, D3.
Even in such a configuration, the valve body is not urged by the differential pressure when it is not operated, so that a similar effect can be obtained.

Further, according to the present embodiment constructed as described above, the driving unit 50 which is disposed on the front side and is made of a magnetic material.
The springs 50 and 51 are separated from each other by a disc spring 53 disposed between the valve seat 51 and a valve seat 51 made of a non-magnetic material. The brake pedal is depressed and the input shaft 24 and the valve plunger 25 are depressed. During normal braking in which the sleeve 18 is advanced, the driving unit 50 and the valve seat 51 are advanced while maintaining the illustrated state until the driving unit 50 contacts the holder 35, and then the driving unit 50 After abutment with the valve 35, the valve seat 51 compresses the disc spring 53 and moves forward relative to the drive unit 50. Therefore, at the time of normal braking, the second valve seat 19 is largely advanced forward with respect to the first valve seat 17, thereby increasing the valve opening amount between the second valve seat 19 and the valve element 21. .
On the other hand, at the time of automatic braking in which the solenoid 23 is excited, the valve seat portion 51 is moved forward integrally with the drive portion 50 while maintaining the illustrated state, and then the drive portion 50 is moved to the holder 3.
After contacting the valve seat 5, the valve seat 51 is stopped by the disc spring 53 while being separated from the drive unit 50. Therefore, at the time of automatic braking, the second valve seat 19 is advanced slightly toward the front side with respect to the first valve seat 17, so that the opening amount of the second valve seat 19 is reduced. In contrast to this embodiment, the conventional valve mechanism is configured so that the opening amount of the second valve seat is the same during normal braking and during automatic braking. Space between drive unit and holder in consideration of responsiveness (solenoid gap)
In the prior art, the opening amount of the second valve seat was relatively small as a result of setting a small value, but it was pointed out that the operation responsiveness during sudden braking during normal depression was poor. According to the example, the opening amount of the second valve seat 19 is reduced during automatic braking, and the opening amount of the second valve seat 19 is increased during normal braking, thereby impairing the operation responsiveness during automatic braking. Without this, it is possible to improve the operation responsiveness during sudden braking during normal braking.

Further, according to this embodiment constructed as described above, the brake pedal is depressed and the valve plunger 2 is depressed.
5, at the time of normal braking in which the sleeve 18, the first member 71 and the second member 72 are engaged and are advanced, the valve body 6 and the power pistons 10, 11 are connected as shown by the solid line in FIG. The reaction disk 41, which has been advanced and compressed between the holder 35 and the output shaft 42, swells and deforms rearward and comes into contact with the small-diameter portion 72A (the first member 72) and the second member 72. The output rises rapidly (jumping) without rising, and after the reaction disk 41 comes into contact with the small-diameter portion 71A of the first member 71 and the second member 72, the reaction force acting on both members is reduced by the valve plunger 2.
5 and the input shaft 24 to the driver, so that the driver can control the brake output with the same feeling as a conventional general brake booster. On the other hand, at the time of automatic braking in which the solenoid 23 is excited, the drive unit 50, the valve seat 51, and the cylindrical unit 73 are advanced integrally until the second valve seat 19 is brought into contact with the holder 35 while maintaining the illustrated state. Is opened, a differential pressure acts on the valve body 6 and the power pistons 10, 11 to advance the valve body 6. Then, as shown by the dashed line in FIG.
Until the reaction disk 41 compressed between the holder 35 and the output shaft 42 expands and deforms toward the rear side and comes into contact with the small diameter portion 71A and the second member 72, the brake reaction force is the same as during normal braking. Output without transmission (brake output)
Rapidly rises (jumping), and the reaction disk 41 comes into contact with the small-diameter portion 71A of the first member 71 and the second member 72, and the two members, the valve plunger 25 and the input shaft 24 are moved to the valve body 6 with respect to the valve body 6. Even if the valve body 6 is relatively retracted (substantially the valve body 6 relatively advances), the output rapidly increases without transmitting the brake reaction force until the first member 71 comes into contact with the cylindrical portion 73. I will be. Then, the second member 72 engaged and retracted with the first member 71 eventually consumes the gap A and abuts on the step of the holder 35 to stop retreating. After retreating, the gap B (specifically, the gap B-the gap C) is consumed and comes into contact with the cylindrical portion 73 stopped at the forward end position with respect to the valve body 6. Then
From this point, the brake reaction force acting on the small diameter portion 71A of the first member 71 is transmitted to the drive unit 50,
Thereafter, the brake output, which has risen sharply, rises at a predetermined servo ratio thereafter, and a servo balance state is established at a position where the brake reaction force and the thrust of the solenoid 23 are balanced. Therefore, by changing the magnetic force of the solenoid 23 to change the thrust of the drive unit 50, the brake output during automatic braking can be controlled against the reaction force acting on the first member 71. At this time, since only the brake reaction force acting on the small diameter portion 71A is transmitted to the drive unit 50, the brake output can be largely changed by a small change in the thrust of the drive unit 50. In contrast to this embodiment, since the conventional automatic brake booster is configured not to transmit the reaction force to the sleeve, the second valve seat is uniformly fully opened at the time of automatic braking, so that the brake is not applied. Although the output could not be controlled and the brake output was excessive in a low speed range, according to the present embodiment, even with a small solenoid 23 having a small magnetic force, the brake output was smoothly controlled by changing the magnetic force. can do. Incidentally, by appropriately setting the area of the small diameter portion 71A of the first member 71, when the solenoid 23 is energized and the driver depresses the brake pedal as shown in FIG. Since the ratio can be set to be large, in this case, a very excellent operation response can be obtained by using the jumping together with the larger jumping than in the normal braking.

FIG. 5 shows a second embodiment of the present invention. In the first embodiment, the small diameter portion 3 of the holder 35 is used.
5b is fitted with the first member 71 and the second member 72
Is fitted to the middle diameter portion 35c, but in the second embodiment, the first member 171 is fitted to the middle diameter portion 135c, and the second member 172 is fitted to the small diameter portion 135b. . The second member 1 is located at the center of the first member 171.
An opening 171a penetrating through the small diameter portion 172A of 72 is provided, and the small diameter portion 172A can be brought into contact with the rear end surface of the reaction disk 141 from the opening 171a. Also, the second member 172
The upper part of the outer peripheral portion is notched, and the cylindrical portion 173 is opposed to the first member 171 through the notch 172b. When the booster is not operated, a gap is formed between the first member 171 engaged with the second member 172 and the cylindrical portion 173, which is equal to the sliding amount of the driving portion. Is configured such that the cylindrical portion 173 advances to the first member 171 at the position shown in FIG. Note that components other than those described above are formed in the same manner as in the first embodiment, and the same members as those in the first embodiment are denoted by reference numerals obtained by adding “100” to the reference numerals used in the first embodiment. .

According to the second embodiment of the present invention, the brake pedal is depressed, and the input shaft, the valve plunger 125, the second member 172 and the first member 171 engaged with the input shaft are advanced. During normal braking, as shown by the solid line in FIG. 6, the valve body 106 and the power piston are advanced and the holder 135 and the output shaft 14 are moved forward.
The reaction disk 141 compressed between the first member 171 and the small diameter portion 172A swells and deforms rearward.
The output increases (jumping) without an increase in the reaction force until the reaction disk 141 comes into contact with the first member 171 and the small-diameter portion 172A until it comes into contact with the (second member 172). The reaction force is the valve plunger 12
5 is transmitted to the driver via the input shaft 5 and the input shaft, so that the driver can control the brake output with the same feeling as a conventional general brake booster. On the other hand, at the time of automatic braking in which the solenoid 123 is excited, the drive unit, the valve seat portion, and the cylindrical portion 173 are integrally advanced until the second valve seat is brought into contact with the holder 135, and the valve body 106 is opened. And the differential pressure acts on the power piston to advance the power piston. Then, the reaction disk 14 compressed between the holder 135 and the output shaft 142
The first member 171 and the small-diameter portion 17
Until the contact with 2A, the output rises (jumping) without transmission of the reaction force, as shown by the dashed line in FIG. And the reaction disk 141 is the first member 1
When the first member 171 contacts the small diameter portion 172A, the first member 171 and the cylindrical portion 173 contacting the first member 171 engage with the second member 172 and retreat. Then, the first member 171 stops at the position where the thrust of the solenoid 123 and the brake reaction force acting on itself are balanced, but the second member 172 is still stopped.
Is retracted and separated from the first member 171,
5 engages with the inner peripheral projection 135d protruding from the small diameter portion 135b and is stopped. As a result, the brake reaction force acting on the second member 172 is received by the valve body 106, and only the brake reaction force acting on the first member 171 is transmitted to the sleeve 118. Therefore, it is clear that the second embodiment can provide the same operation and effect as the first embodiment. By the way, in the second embodiment, unlike the first embodiment, the valve plunger 125 is configured to contact the second member 172 even when the solenoid 123 is energized and the driver depresses the brake pedal. Therefore, at this time, the same servo ratio as that during normal braking can be obtained by setting the area of the first member 171 and the area of the small diameter portion 172A of the second member 172 as shown by a two-dot chain line in FIG. With this setting, even if the driver depresses the brake pedal during automatic braking, the driver can operate without feeling uncomfortable.

FIG. 7 shows a third embodiment of the present invention. In the second embodiment, the small diameter portion 172A of the second member 172 is brought into contact with the reaction disk 141 by passing through the inside of the first member 171. However, in the third embodiment, the first member 271 is housed in the concave portion 272a formed at the center of the large-diameter portion 271A of the second member 272, and the leg portion extending rearward from the first member 271 is provided. 271 a is made to protrude rearward through a through hole 272 c formed in the upper part of the second member 272 to face the cylindrical portion 273. Also, in the third embodiment, as in the second embodiment, when the booster is not operated, the drive unit slides between the leg 271a of the first member 271 and the cylinder 273 which engages with the second member 272. It forms a gap slightly larger than the volume. The configuration other than the above is formed in the same manner as in the second embodiment, and the same members as in the second embodiment have the same reference numerals as those used in the second embodiment, ie, "100".
Is added. Also in the third embodiment having such a configuration, the brake reaction force acting on the first member 271 and the small diameter portion 272A is transmitted to the driver during normal braking, whereas the first member 271 during automatic braking.
The second member 272 is separated from the cylindrical portion 273 to stop retreating. However, since the second member 272 is separated from the cylindrical portion 273 and stopped against the valve body 206, the same operation and effect as in the second embodiment can be obtained. .

FIG. 8 shows a fourth embodiment of the present invention. In the third embodiment, when the booster is not operated, the first member 271 is engaged with the second member 272. The gap between the cylinder 271a and the cylindrical portion 273 must be set to be substantially the same as the sliding amount of the driving unit, so that the third embodiment has a smaller jumping than the first embodiment by the reduced gap. However, in the fourth embodiment, the other leg portion 371a 'is brought into contact with the valve plunger 325 so that one leg portion 371a is connected to the cylindrical portion 37 when the booster is not operated.
3 is separated by a gap B. Note that components other than those described above are formed in the same manner as in the third embodiment, and the same members as those in the third embodiment are denoted by reference numerals obtained by adding “100” to the reference numerals used in the third embodiment. . According to the fourth embodiment having such a configuration, jumping can be further increased while maintaining the operation and effect of the third embodiment, so that the initial braking force can be improved.

FIG. 9 shows a fifth embodiment of the present invention. In the fourth embodiment, the first member 3 is provided in the second member 372.
However, in the fifth embodiment, the first member 47 is accommodated.
The first member 472 is accommodated in the first member 1 so that the same operation and effect as those of the fourth embodiment can be obtained. That is, the first member 471 is formed into a stepped cylindrical shape from the small diameter portion 471A and the large diameter portion 472B fitted to the small diameter portion 435b and the middle diameter portion 435c of the holder 435, and the inner diameter thereof is set to the valve plunger 425. Is formed smaller in diameter than the small-diameter portion 425A, so that the rear-side end surface can abut on the valve plunger 425 or the cylindrical portion 473. When the first member 471 abuts on the valve plunger 425 and is not operated, a gap B is formed between the small diameter portion 471A of the first member 471 and the cylindrical portion 473. On the other hand, the second member 472 is formed in a cylindrical
An engagement that is slidably fitted in a through hole 471C formed in the shaft of the member 471 and that protrudes radially outward through a slide hole 471D formed in the outer periphery of the first member 471. The engaging portion 472A is accommodated in a notch 435e obtained by cutting out a part of the small diameter portion 435b of the holder 435. Then, the second member 47
When the valve 2 is not in contact with the valve plunger 425, the engagement portion 472A is separated from the bottom of the notch 435e by a gap C and is separated from the front side. When the booster is not operated, the engaging portion 472A and the slide hole 471 are not operated.
A gap B is formed between the first member 471 and the second member 472 so that the first member 471 can be relatively displaced rearward with respect to the second member 472. Even in the fifth embodiment having such a configuration in which the first member 471 can shift to the rear side by the gap B, the same operation and effect as those of the fourth embodiment can be obtained. Can be.

FIG. 10 shows a sixth embodiment of the present invention. In any of the first to fifth embodiments, when the booster is not operated, the first member and the cylindrical portion are interposed. Although the gap is formed, in the sixth embodiment, the first member 571 is brought into contact with the cylindrical portion 573, and between the first member 571 and the second member 572 which is in contact with the valve plunger 525. A predetermined gap is formed. More specifically, the first member 571 is formed in a disk shape, and the large-diameter portion 572 of the second member 572 fitted in the holder 535.
A is fitted into the recess 572a formed in the second member 572, and the leg 571 is inserted through the through hole 572b formed in the second member 572.
a is projected to the rear side and abuts on the cylindrical portion 573. When the booster is not operated, a gap is formed between the rear end surface of the first member 571 and the bottom surface of the concave portion 572a of the second member 572, and the first member 571 is moved forward with respect to the second member 572. It protrudes to the side. In the first embodiment, the disc spring 53 is disposed between the drive unit 50 and the valve seat 51. In the third embodiment, a coil spring 553 is elastically mounted instead of the disc spring 53. . In the sixth embodiment, an elastic member 575 is provided on the rear end surface of the holder 535 along the circumferential direction to prevent a tapping sound when the driving unit 550 comes into contact. The configuration other than that described above is the same as that of the first embodiment, and the same members as those of the first embodiment are denoted by the same reference numerals as those used in the first embodiment plus "500". I have.

According to the sixth embodiment of the present invention, the brake pedal is depressed, and the input shaft 52 is depressed.
4. During normal braking in which the valve plunger 525 and the sleeve 518 engaged with the valve plunger 525 are advanced, the first member 5
The first member 71 and the second member 572 are advanced while maintaining the illustrated state. Then, as shown in FIG. 11, the brake reaction force is applied until the reaction disk 541 compressed between the holder 535 (valve body 506) and the output shaft 542 contacts the first member 571 closer to the second member 572. When the reaction disk suddenly rises (straight line A) without transmitting the force, and the reaction disk comes into contact with the first member 571, the cylindrical portion 573, the driving portion 550, and the coil spring 55
3. Since the brake reaction force is transmitted to the valve plunger 525 via the first member 551, the coil spring 55
Until the set load of No. 3 is exceeded, the output sharply increases along the slope of the straight line B. Then, when the brake reaction force exceeds the set load of the coil spring 553 and the coil spring is compressed, the output sharply rises along the slope of the straight line C, and the first member 571 is seated on the second member 572. After the reaction disk 541 suddenly rises along the slope of the straight line D and then comes into contact with the front end surface of the second member 572, the first member 571 and the second member 572
And the brake reaction force acting on the line E is transmitted at the same time, and thereafter the output gradually rises to the full load state along the slope of the straight line E. Therefore, the straight line A, the straight line B, the straight line C, and the straight line D correspond to substantial jumping, so that the driver hardly feels a sense of discomfort, and the brake output is sensed in the same manner as a conventional brake booster. Can be controlled.
On the other hand, at the time of automatic braking in which the solenoid 523 is excited, the drive unit 550, the valve seat 551, the cylinder 573, and the first member 571 in contact with the same are advanced while maintaining the illustrated state. Then, the reaction disk 54 compressed between the holder 535 and the output shaft 542
1 immediately comes into contact with the approached first member 571, whereby the brake reaction force acting on the first member 571 is immediately transmitted to the sleeve 518,
On the other hand, since the second member 572 is retracted by the reaction disk 541 and abuts on the valve body 506,
Thereafter, the output rises along a predetermined straight line E 'as shown by a dashed line. Therefore, in the sixth embodiment, unlike the first to fifth embodiments, the jumping at the time of the automatic braking is set to be small, whereby the magnetic force of the solenoid 523 is changed so that the braking from a small output range can be performed. Output can be controlled smoothly.

FIG. 12 shows a seventh embodiment of the present invention. In the sixth embodiment, the brake reaction force acting on the first member 571 at the initial stage of the normal braking is applied to the cylindrical portion 573.
And the drive unit 550, the coil spring 553, the first member 55
1, the transmission is transmitted to the valve plunger 525.
The brake reaction force acting on the member 671 is applied to the valve plunger 62.
5 and directly. That is, the first member 671 is connected to the large diameter portion 672 of the second member 672.
a front part 671A housed in a.
And a rear portion 671B housed in the notch 672b of the second member 672 so as to be relatively displaceable.
The front portion 671A is formed in a columnar shape. When the booster is not operated, the front end face is opposed to the rear end face of the reaction disk 641 with a predetermined gap, and the rear end face is connected to the rear end face. It is in contact with the front end face of the portion 671B. Also, the rear portion 67
1B is a main body portion 671B ′ formed in a substantially cylindrical shape,
And a leg 671b extending rearward from the upper end of the rear end face of the main body 671B '. When the booster is not operated, the rear end face of the main body 671B' is connected to the small diameter portion 625A of the valve plunger 625. While being in contact with the front end surface, the leg portion 671b is in contact with the tubular portion 673 or is opposed to the tubular portion 673 with a small gap. The configuration other than that described above is the same as that of the sixth embodiment, and the same members as those of the first embodiment have the same reference numerals as those used in the first embodiment.
0 is added.

According to the seventh embodiment of the present invention having the above-described structure, when the brake pedal is depressed, the input shaft, the valve plunger 625, and the sleeve 618 engaged with the input shaft are moved forward during normal braking. Member 671 (front portion 671A, rear portion 671B) and second member 672
Are advanced while maintaining the illustrated state. Then Figure 13
As shown in FIG. 7, the reaction disk 641 compressed between the holder 635 (valve body 606) and the output shaft 642 is closer to the front portion 67 than the second member 672.
Until it comes into contact with 1A, the output sharply increases without transmission of the brake reaction force (straight line A).
1 comes into contact with the front portion 671A, the brake reaction force is applied via the rear portion 671B to the valve plunger 625.
, The output sharply rises along a straight line B having a large inclination. Then, when the reaction disk 641 is still compressed between the holder 635 and the output shaft 642 and abuts on the second member 672 located on the rear side of the first member 671 (the front portion 671a), the first disk is thereby released. Since the brake reaction force acting on the member 671 and the second member 672 is simultaneously transmitted to the valve plunger 625, the output is thereafter gradually increased along the slope of the straight line C to the full load state. Become. Therefore, at the time of normal braking, the substantial jumping that allows the driver to feel the braking reaction force during normal braking due to the action of the straight line B having a large increase in output is larger than the numerical jumping Q. A straight line B
The intersection P between the straight line C and the straight line C is positioned as the jumping P during normal braking.
Is the servo area. As a result, the driver can control the brake output at intervals similar to those of a conventional general brake booster. On the other hand, at the time of automatic braking in which the solenoid 623 is excited, the drive unit 650, the valve seat (not shown), the cylinder 673, and the rear part 671 abutting on this.
B and the front part 671A are advanced relatively to the second member 672. Then, the reaction disk 6 compressed between the holder 635 and the output shaft 642
41 comes into contact with the approaching front portion 671A, whereby the brake reaction force acting on the front portion 671A is transmitted to the drive portion 650 via the rear portion 671B and the cylindrical portion 673. The output sharply increases along a straight line B having a large inclination. And
When the reaction disk 641 is still compressed between the holder 635 and the output shaft 642, the reaction disk 641 comes into contact with the second member 672 located on the rear side of the first member 671. At this time, the brake reaction force acting on the second member 672 is received by the valve body 606 with which the second member 672 abuts, so that the output continuously rises rapidly along the straight line B to the full load state. Become. Therefore, in the seventh embodiment, the jumping at the time of automatic braking is set to be smaller than that of the first to fifth embodiments, and the servo ratio at the time of automatic braking is set to be larger than the servo ratio at the time of normal braking. As a result, it is possible to smoothly control a large output with a small solenoid thrust. In the seventh embodiment, the first member 671 is composed of the front part 671A and the rear part 671B. However, the present invention is not limited to this.
The leg portion 371a of the first member 371 of the embodiment is extended to the rear side, or the cylindrical portion 373 is extended to the front side, and the leg portion 371a is extended.
The first member 371 is also integrated with the first member 371 by bringing the cylinder 71a into contact with the cylindrical portion 373 when the booster is not operating.
The same operation and effect as the embodiment can be obtained.

In each of the first to seventh embodiments, the elastic member is elastically mounted on the drive portion forming the sleeve and the valve seat portion. However, the present invention is not limited to this. An elastic member may be elastically mounted between a sleeve and a valve body (holder) in which the valve body and the valve seat are integrally connected.

[0031]

As described above, according to the present invention, it is possible to improve the operation responsiveness at the time of sudden braking during normal braking without impairing the operation responsiveness at the time of automatic braking. The effect that the brake output at the time of braking can be controlled smoothly is obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is an enlarged sectional view of a valve mechanism 15;

FIG. 4 is a characteristic diagram of the first embodiment.

FIG. 5 is an enlarged sectional view of a main part showing a second embodiment of the present invention.

FIG. 6 is a characteristic diagram of the second embodiment.

FIG. 7 is an enlarged sectional view of a main part showing a third embodiment of the present invention.

FIG. 8 is an enlarged sectional view of a main part showing a fourth embodiment of the present invention.

FIG. 9 is an enlarged sectional view of a main part showing a fifth embodiment of the present invention.

FIG. 10 is an enlarged sectional view of a main part showing a sixth embodiment of the present invention.

FIG. 11 is a characteristic diagram of the sixth embodiment.

FIG. 12 is an enlarged sectional view of a main part showing a seventh embodiment of the present invention.

FIG. 13 is a characteristic diagram of the seventh embodiment.

[Explanation of symbols]

6, 106, 206, 306, 406, 506, 606
... valve body 15, 115, 515 ... valve mechanism 17, 117, 517 ... first valve seat 18, 118, 518, 618 ... sleeve 19, 119, 519 ... second valve seat 20, 120, 520 ... poppet return spring 21 , 121, 521 ... valve body 22, 122, 522 ... biasing spring 23, 123, 223, 323, 423, 523, 62
3. Solenoid 32, 132 Sealing member 35, 135, 235, 335, 435, 535 ... Holder 40, 140, 240, 340, 440, 540, 64
0: Plate plunger 41, 141, 241, 341, 441, 541, 64
DESCRIPTION OF SYMBOLS 1 ... Reaction disk 50, 150, 550, 650 ... Drive part 51, 151, 551 ... Valve seat part 52, 152, 552 ... Engagement part 53, 153 ... Disc spring 553 ... Coil spring 71, 171, 271, 371, 471, 571, 67
1. First member 72, 172, 272, 372, 472, 572, 67
2nd member

Claims (8)

[Claims] 1. A valve body slidably provided in a shell, a power piston provided in the valve body, a constant pressure chamber and a variable pressure chamber formed before and after the power piston.
A valve mechanism provided in the valve body for performing switching control of the flow path, the valve mechanism comprising: a first valve seat formed in the valve body; a sleeve slidably fitted in the valve body; A second valve seat formed in the sleeve, a valve element seated on the first valve seat and the second valve seat, a driving means for displacing the sleeve to the front side to switch the flow path, and An automatic brake booster comprising: a valve plunger provided in the valve body and the sleeve so as to be relatively displaceable and interlocked with the input shaft, and displacing the sleeve toward the front side when the input shaft advances to switch the flow path. In the device, the sleeve is displaced to the front side by the drive means, and the second valve seat is displaced to the front side by the valve plunger. A valve seat portion, an engaging portion that engages with the valve seat portion when the driving portion is displaced to the front side and displaces the valve seat portion to the front side, and is disposed between the driving portion and the valve seat portion. An elastic member that separates the two members from each other. The elastic member holds the driving unit and the valve seat in a separated state when the driving unit is displaced to the front side by the driving unit. An automatic brake booster characterized in that when the plunger is displaced to the front side by a plunger, the valve seat is compressed to bring the drive unit and the valve seat close to each other to increase the opening amount of the second valve seat. 2. A valve body slidably provided in a shell, a power piston provided on the valve body, a constant pressure chamber and a variable pressure chamber formed before and after the power piston.
A valve mechanism provided in the valve body for performing switching control of the flow path, the valve mechanism comprising: a first valve seat formed in the valve body; a sleeve slidably fitted in the valve body; A second valve seat formed in the sleeve, a valve element seated on the first valve seat and the second valve seat, a driving means for displacing the sleeve to the front side to switch the flow path, and An automatic brake booster comprising: a valve plunger provided in the valve body and the sleeve so as to be relatively displaceable and interlocked with the input shaft, and displacing the sleeve toward the front side when the input shaft advances to switch the flow path. In the device, an elastic member is disposed at a predetermined space between the front side of the sleeve and the valve body, and the elastic member is provided on the front of the sleeve by the driving means. When the sleeve is displaced to the front side, the sleeve is prevented from being displaced to the front side without being substantially compressed. When the sleeve is displaced to the front side by the valve plunger, the sleeve is compressed to increase the opening amount of the second valve seat. An automatic brake booster characterized in that: 3. A valve body slidably provided in a shell, a power piston provided in the valve body, a constant pressure chamber and a variable pressure chamber formed before and after the power piston.
A valve mechanism provided on the valve body, an input shaft for switching a flow path of the valve mechanism by moving a valve plunger that constitutes the valve mechanism, and an output shaft slidably provided on the valve body; A valve disc interposed between the base of the output shaft and the valve plunger; and a plate plunger, wherein the valve mechanism is slidably fitted into a first valve seat formed in the valve body and into the valve body. A sleeve, a second valve seat formed in the sleeve, a valve element seated on the first valve seat and the second valve seat, and a driving means for displacing the sleeve to the front side to switch the flow path And the valve body and the sleeve are provided so as to be relatively displaceable and are interlocked with the input shaft. When the input shaft advances, the sleeve is displaced to the front side to switch the flow path. In the automatic brake booster provided with the valve plunger, the plate plunger includes a first member and a second member which are provided so as to be able to come and go in the axial direction and mutually contact the reaction disk. The one member engages with the second member during normal braking to transmit a brake reaction force acting on the second member and a brake reaction force acting on itself to the valve plunger, and abuts on the valve body during automatic braking. An automatic brake booster, which transmits a brake reaction force acting on the sleeve away from the second member to the sleeve. 4. The automatic brake booster according to claim 3, wherein a predetermined gap is formed between the first member and the sleeve when the booster is not operated. 5. A gap between the first member and the sleeve is set to be larger than a sum of a gap between the second member and the valve body and a gap between the second valve seat and the valve body. The automatic brake booster according to claim 4, wherein 6. A valve body slidably provided in a shell, a power piston provided in the valve body, a constant pressure chamber and a variable pressure chamber formed before and after the power piston.
A valve mechanism provided on the valve body, an input shaft for switching a flow path of the valve mechanism by moving a valve plunger that constitutes the valve mechanism, and an output shaft slidably provided on the valve body; A valve disc interposed between the base of the output shaft and the valve plunger; and a plate plunger, wherein the valve mechanism is slidably fitted into a first valve seat formed in the valve body and into the valve body. A sleeve, a second valve seat formed in the sleeve, a valve element seated on the first valve seat and the second valve seat, and a driving means for displacing the sleeve to the front side to switch the flow path And the valve body and the sleeve are provided so as to be relatively displaceable and are interlocked with the input shaft. When the input shaft advances, the sleeve is displaced to the front side to switch the flow path. An automatic brake booster including a valve plunger, wherein the plate plunger is provided so as to be relatively displaceable in an axial direction, and includes a first member and a second member that abut against each other with a reaction disk. One member transmits the brake reaction force acting on itself to the valve plunger through the sleeve during normal braking to the valve plunger, and also applies the own brake reaction force to the sleeve separated from the valve plunger during automatic braking. The second member contacts the valve plunger during normal braking to transmit a brake reaction force acting on the valve plunger itself, and at the time of automatic braking, the second member contacts the valve body and acts on the valve body itself. An automatic brake booster for transmitting a reaction force to the valve body. 7. A valve body slidably provided in a shell, a power piston provided in the valve body, a constant pressure chamber and a variable pressure chamber formed before and after the power piston.
A valve mechanism provided on the valve body, an input shaft for switching a flow path of the valve mechanism by moving a valve plunger that constitutes the valve mechanism, and an output shaft slidably provided on the valve body; A valve disc interposed between the base of the output shaft and the valve plunger; and a plate plunger, wherein the valve mechanism is slidably fitted into a first valve seat formed in the valve body and into the valve body. A sleeve, a second valve seat formed in the sleeve, a valve element seated on the first valve seat and the second valve seat, and a driving means for displacing the sleeve to the front side to switch the flow path And the valve body and the sleeve are provided so as to be relatively displaceable and are interlocked with the input shaft. When the input shaft advances, the sleeve is displaced to the front side to switch the flow path. An automatic brake booster including a valve plunger, wherein the plate plunger is provided so as to be relatively displaceable in an axial direction, and includes a first member and a second member that abut against each other with a reaction disk. One member transmits a brake reaction force acting on itself to the valve plunger during normal braking to contact the valve plunger, and transmits its own brake reaction force to the sleeve separated from the valve plunger during automatic braking, The second member contacts the valve plunger during normal braking to transmit the brake reaction force acting on the valve plunger itself, and at the time of automatic braking, contacts the valve body to reduce the brake reaction force acting on itself. An automatic brake booster for transmitting to the valve body. 8. The automatic brake booster according to claim 1, wherein said driving means is a solenoid.