JP2000127947A - Brake booster - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely detect a tandem brake booster operated as an automatic brake by a detection means. SOLUTION: A piston 48 and a cylindrical member 18 are moved to a front side relating to a valve body 6 from a non-operation condition as shown in the drawing by exciting a solenoid 16. In this way, an atmospheric air valve seat 21 provided in the cylindrical member 18 is detached from a second seat part S2 of a valve element 24 to open an atmospheric air valve 28, and a vacuum valve 25. Accordingly, a tandem brake booster 1 is operated as an automatic brake. A detection means 54 comprising a rod member 55 and a micro- switch 56 is provided in a rear side of the cylindrical member 18. When the cylindrical member 18 is moved to the front side relating to a valve plunger 22 and an input shaft 35 as described, the rod member 55 is also moved to swing a movable contact 56a of the micro-switch 56.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake booster, and more particularly to a brake booster having a function as an automatic brake.

[0002]

2. Description of the Related Art Conventionally, as a brake booster having a function as an automatic brake, for example, Japanese Unexamined Patent Publication No. Hei.
No. 58 is known. The brake booster disclosed in the above publication includes a solenoid in a valve body, and when the solenoid is operated, the valve mechanism is operated in conjunction therewith. Therefore, when the solenoid is operated, the brake booster can be operated as an automatic brake without depressing the brake pedal.

[0003]

By the way, in the above-mentioned conventional device, it is possible to detect that the brake booster is operated as an automatic brake by detecting the current supplied to the solenoid. It is.
However, in this case, even if the current supplied to the solenoid is detected, the valve mechanism of the brake booster may not be operated for some reason, and conversely, the supply of power to the solenoid may be stopped. In some cases, the valve mechanism remained activated. Therefore, there is a disadvantage that it is not possible to reliably detect whether or not the brake booster has been operated as an automatic brake only by detecting the current supplied to the solenoid. A brake booster having a function as an automatic brake is disclosed in
No. -86395 is also known. The device of this publication includes a detecting means for detecting that the brake pedal is depressed, and when the detecting means detects that the brake pedal is depressed, the solenoid is excited to operate the brake booster. I have to. However, the detecting means disclosed in Japanese Patent Application Laid-Open No. 9-86395 only detects that the brake pedal is depressed, and detects whether or not the brake booster is operated as an automatic brake. It was not something. Therefore, there has been a demand for a device capable of reliably detecting whether or not the brake booster has been operated as an automatic brake.

[0004]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides a substantially cylindrical valve body slidably provided in a shell, a power piston provided in the valve body, and a power piston provided before and after the power piston. A constant pressure chamber and a variable pressure chamber formed in a partition, an annular vacuum valve seat formed in the valve body, a valve plunger movably provided in the valve body and interlocking with the input shaft, and slidable on the outer peripheral portion of the valve plunger. A cylindrical member provided on the cylindrical member, an annular atmospheric valve seat formed on the cylindrical member, and a valve body which is urged toward the front side by a spring and comes into contact with and separates from the vacuum valve seat and the atmospheric valve seat. A vacuum valve formed by the vacuum valve seat and a first seat portion of a valve body that comes and comes in contact with the vacuum valve seat; Empty outside the vacuum valve A constant-pressure passage for communicating the pressure chamber with the constant-pressure chamber, a variable-pressure passage for communicating the space between the vacuum valve and the atmospheric valve with the variable-pressure chamber, and an atmospheric passage for communicating the space inside the atmospheric valve with the atmosphere. And a drive mechanism for moving the tubular member to the operating position, wherein the drive mechanism moves the tubular member to the operating position, closes the vacuum valve seat, and closes the atmosphere valve. A detection means is provided for detecting that the tubular member has moved to the operating position when opened.

[0005]

According to such a construction, when the cylindrical member is moved to the operating position by the drive mechanism to close the vacuum valve seat and open the atmospheric valve, the brake is applied without depressing the brake pedal. The booster is operated as an automatic brake. Then, at that time, the detection means can detect that the tubular member has moved to the operating position. Therefore, it is possible to reliably detect that the brake booster has been operated as an automatic brake.

[0006]

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 has a center plate 3 provided at a center portion thereof and a front chamber 4 on the front side and a rear side. And the rear chamber 5 on the side. Then, the roughly cylindrical valve body 6 is
Sealing means 7 and 8 are used to seal and penetrate the inner peripheral portion of the shell 2 on the rear side (right side) and the inner peripheral portion of the center plate 3 while maintaining airtightness. A front power piston 11 and a rear power piston 12 are connected to the outer periphery of the valve body 6 located in the front chamber 4 and the rear chamber 5, respectively. 13 and a rear diaphragm 14 are respectively stretched. The front diaphragm 13 partitions the front chamber 4 into a constant-pressure chamber A and a variable-pressure chamber B, and the rear diaphragm 14 partitions the rear chamber 5 into a constant-pressure chamber C and a variable-pressure chamber D. In the valve body 6, a valve mechanism 15 for switching the communication between the constant pressure chambers A and C and the variable pressure chambers B and D is provided, and a solenoid 16 is disposed on the front side of the valve mechanism 15. The valve mechanism 15 includes an annular vacuum valve seat 17 provided on an inner peripheral portion of the valve body 6 and a valve body 6.
A cylindrical member 18 movably provided in the axial direction with respect to the cylindrical member 18, an annular atmospheric valve seat 21 formed on the cylindrical member 18, and an input shaft slidably fitted in the cylindrical member 18. 35
A valve plunger 22 interlocked with the valve seats 17 and 21
, Which is seated from the rear side by a spring 23
And

The above-mentioned vacuum valve seat 17 and the valve body 2 which comes into contact with and separates from the same.
4 and the first seat portion S1, the vacuum valve 25 is formed. A space on the outer peripheral side of the vacuum valve 25 communicates with the constant pressure chamber A through a first constant pressure passage 26 formed in the valve body 6. The inside of the constant-pressure chamber A communicates with the constant-pressure chamber C via a second constant-pressure passage 27 continuous from the first constant-pressure passage 26. The inside of the constant pressure chamber A communicates with a negative pressure source via a negative pressure introducing pipe (not shown), whereby a constant negative pressure is introduced into the constant pressure chambers A and C. The atmosphere valve 28 is constituted by the atmosphere valve seat 21 and the second seat portion S2 of the valve element 24 which comes into contact with and separates from the atmosphere valve seat 21. The space between the second seat portion S2 and the first seat portion S1 communicates with the variable pressure chamber D via a first variable pressure passage 31 formed in the valve body 6 in the radial direction. Communicates with the variable pressure chamber B via a second variable pressure passage 32 formed in the valve body 6. Further, a space on the inner peripheral side of the atmosphere valve 28 communicates with the atmosphere via an atmosphere passage 33 formed in the valve body 6 and a filter 34 provided therein. The distal end of an input shaft 35 is pivotally connected to the rear end of the valve plunger 22. A larger spring than the spring 23 is provided between the input shaft 35 and a retainer fitted to the valve body 6. A spring 36 having a force is mounted. Thereby, in the non-operation state of the tandem brake booster 1 shown in FIG. 1, the second seat portion S2 of the valve body 24 is seated on the atmosphere valve seat 21 to close the atmosphere valve 28, and the valve body 24 is closed. The first seat portion S1 is separated from the vacuum valve seat 17 and the vacuum valve 2
5 is open. The end of the input shaft 35 is linked to a brake pedal (not shown). In this non-operating state, the chambers A, B, C, and D communicate with each other,
A negative pressure is introduced into each of the chambers A, B, C, and D.

Further, a radial hole 6A is formed in the valve body 6 at the front side of the first variable pressure passage 31. A conventionally known key member 37 is inserted into the radial hole 6A and the key member 37 is inserted into the radial hole 6A. 37 is engaged with the engaging portion 22a of the valve plunger 22. When the tandem brake booster 1 shown in FIG. 1 is not operated, the key member 37 is brought into contact with the rear wall surface 2a of the shell 2 so that the key member 37 and the valve plunger 22 are moved forward with respect to the valve body 6. To keep it. Thereby, the input shaft 3 at the time of starting the operation of the tandem brake booster 1
5, the loss stroke is reduced. A housing 41 of a solenoid 38 is fitted to the position where the radial hole 6A is provided and the inner peripheral portion of the valve body 6 on the front side thereof while maintaining airtightness. The housing 41 is formed in a substantially cylindrical shape, and houses a spool 42 around which a coil is wound on the outer peripheral side. A plunger plate 43 is slidably fitted to the inner peripheral portion on the front side of the housing 41. The inner peripheral portion of the housing 41 on the front side of the plunger plate 43 is a large-diameter portion 41a in which a disk-shaped reaction disk 44 is stored. The plunger plate 43 of the present embodiment includes a columnar member 43A located on the rear side and an annular member 43B located on the front side. A columnar projection is formed on the front end surface of the columnar member 43A, and the projection penetrates the annular member 43B from the rear side. As a result, the shaft of the rear end surface of the reaction disk 44 faces the end surfaces of the projections of the annular member 43B and the columnar member 43A.

An output shaft 45 is disposed on the front side of the reaction disk 44, and the output shaft 45
The large-diameter base portion 45a is slidably fitted to the large-diameter portion 41a of the housing 41 and abuts against the reaction disk 44 from the front side. This allows
The reaction disk 44 is connected to the rear end surface of the base 45 a of the output shaft 45 and the large-diameter portion 41 of the housing 41.
a between the end face of the step. In addition, the reaction disk 44 and the front end surface of the plunger plate 43 (the end surface of the projection of the columnar member 43A) face each other with a slight separation. A dish-shaped retainer 46 is fitted on the front end of the housing 41, and the base 45 a of the output shaft 45 is attached by the retainer 46.
From the large diameter portion 41a of the housing 41. A return spring 47 is elastically mounted on an outer peripheral portion of the retainer 46 and a wall surface on the front side of the shell 2, thereby holding the valve body 6 and the like at a non-operating position in the drawing. The front end of the output shaft 45 projects outward from the front wall surface of the shell 2 and is linked to the piston of a master cylinder (not shown).
Plunger plate 4 at the inner periphery of housing 41
3 is provided with a cylindrical piston 48 made of a magnetic material.
Are slidably fitted. In the present embodiment, the solenoid 16 is of an ON-OFF control type, and the operation of the solenoid 16 is controlled by a control device (not shown). When the solenoid is excited by the control device, the piston 48 is moved to the front side with respect to the housing 41 and the valve body 6.

In the present embodiment, the cylindrical member 18 is arranged on the rear side of the piston 48, and the piston 48 and the cylindrical member 18 are interlocked with each other, and the valve plunger 22 is slid inward of them. They are freely fitted. Piston 4
8, a cylindrical portion 48a extending toward the front side is formed on the front shaft portion, and the tip of the cylindrical portion 48a is brought into contact with the rear end surface of the plunger plate 43 (columnar member 43A). ing. On the other hand, a dish-shaped engaging portion 48b is formed on the rear shaft portion of the piston 48. The rear end of the engaging portion 48b is a flange extending radially outward. On the other hand, the cylindrical member 18 is formed in a stepped cylindrical shape in which the front side is sequentially reduced in diameter, and the front end of the small-diameter portion 18A is bent inward in the radial direction to serve as a locking portion. The rear end of the radial portion 18C is also extended inward in the radial direction to form the radial portion 1C.
8D. Then, the small diameter portion 18A of the cylindrical member 18 is inserted into the inner peripheral portion of the housing 41, and the small diameter portion 18A is inserted.
A front end (locking portion) of A is slidably fitted on the outer peripheral portion of the engaging portion 48b of the piston 48, whereby the front end (locking portion) of the small diameter portion 18A is attached. , Between the rear end surface of the piston 48 and the flange portion of the engaging portion 48b. At the same time, the cylindrical member 1
8, the outer peripheral portion of the middle diameter portion 18B is freely fitted to the inner peripheral portion of the housing 41 when sliding. Since the spring 51 is mounted on the rear end surface of the piston 48 and the stepped end surface of the cylindrical member 18 opposed thereto, the piston 48
And the cylindrical member 18 are urged in a direction (left-right direction) apart from each other, and the small-diameter portion 18A of the cylindrical member 18 is locked to the flange portion (rear end portion) of the engaging portion 48b of the piston 48. Department is in contact.

In the valve element 24 of the present embodiment, the first seat portion S1 and the second seat portion S2 are separated in the axial direction, and their diameters are set to the same size. The large-diameter portion 18C of the cylindrical member 18 is connected to the first sheet portion S1.
And the second seat portion S2. In this embodiment, the atmospheric valve seat 21 is constituted by the outer peripheral edge of the radial portion 18D of the cylindrical member 18. Next, valve plunger 2
In the second embodiment, since the air valve seat 21 is formed on the cylindrical member 18 in the present embodiment, unlike the conventional general one, the air valve seat 21 is formed on the valve plunger 22 of the present embodiment. Instead, the front side is formed in a stepped rod shape whose diameter gradually decreases. The valve plunger 22 has a front-side portion as a small-diameter portion 22bb, a rear-side portion as a middle-diameter portion 22c, and a rear-side portion as a large-diameter portion 22d. The rear end of the large-diameter portion 22d is extended radially outward to form a flange portion 22e.
And The valve plunger 22 slidably penetrates the small-diameter portion 22b of the piston 48 from the rear side and slidably fits a portion of the valve plunger 22 closer to the rear side than the middle-diameter portion 22c to the inner peripheral portion of the tubular member 18. I agree. That is, the middle diameter portion 22
c is on the inner periphery of the small-diameter portion 18A of the tubular member 18, and the large-diameter portion 22d is on the inner periphery of the middle-diameter portion 18B of the tubular member 18.
Further, the large diameter portion 18C of the cylindrical member 18
Are slidably fitted to the inner peripheral portion of each. A seal member 52 is attached to an outer peripheral portion of the flange portion 22e, thereby maintaining airtightness between the flange portion 22e and an inner peripheral portion of the large-diameter portion 18C of the tubular member 18. An annular groove is formed in a region on the rear side of the middle diameter portion 22c, and is used as an engaging portion 22a with which the key member 37 is engaged.
The key member 3 is provided on the middle diameter portion 18B of the cylindrical member 18.
7 is formed with a notch that allows the engaging portion 22a to be inserted into the engaging portion 22a. Further, as described above, the input shaft 35 is pivotally connected to the shaft portion on the rear side of the valve plunger 22.

Further, a spring 53 is elastically mounted on a shaft portion on the rear side of the valve plunger 22 and a radial portion 18D of the cylindrical member 18 opposed thereto. As a result, the valve plunger 22 is urged toward the front side with respect to the tubular member 18 so that the flange portion 22e is formed in a stepped section between the large diameter portion 18C and the middle diameter portion 18B of the tubular member 18. The end face on the front side of the valve plunger 22 (the end face on the front side of the small-diameter portion 22B) is maintained at the contact position, and the plunger plate 43 (the cylindrical member 43)
A) is in contact with the rear end surface of FIG. As detailed later,
In the non-operating state shown, the solenoid 16 is not operated, and the atmospheric valve 28 is closed, while the vacuum valve 25 is open. When the brake pedal is depressed from this state, the input shaft 35, the valve plunger 22, and the cylindrical member 18 are depressed.
Are integrally advanced, the atmospheric valve 28 is opened, the vacuum valve 25 is closed, and the tandem brake booster 1 is operated. When the solenoid is excited by the control device from the non-operating state in which the solenoid 16 is not operated, the piston 48 and the cylindrical member 18 are moved to the front side with respect to the valve plunger 22. Is opened, while the vacuum valve 25 is closed. Therefore, the tandem brake booster 1 is operated without depressing the brake pedal. In other words, the tandem brake booster 1 can be operated as an automatic brake by exciting the solenoid 16 from the non-operating state shown.

In this embodiment, on the premise of the above-described configuration, a detection means 54 for detecting that the tandem brake booster 1 has been operated as an automatic brake is added. That is, the valve body 24 is provided in the valve body 6.
A rod member 55 serving as a detected portion is disposed from the inside to the rear side of the rod member 55. A cylindrical sliding portion 55a of the rod member 55 is slidably fitted on the outer peripheral portion of the input shaft 35. I have. Input shaft 3 on the rear side of rod member 55
5 is provided with a microswitch 56 as a detection unit.
Is fixed. The micro switch 56 has a movable contact 56a provided to be swingable. The front end of the rod member 55 is connected to the radial portion 18 of the cylindrical member 18.
D is contacted from the rear side, and the rear end of the rod member 55 is connected to the movable contact 5 of the microswitch 56.
6a. The detecting means 54 is constituted by the rod member 55 and the microswitch 56. At the time of normal brake operation in which the brake pedal is depressed, the valve plunger 22, the cylindrical member 18, the rod member 5
5. The micro switch 56 is moved forward and backward integrally with the input shaft 35. That is, since the valve plunger 22 and the input shaft 35 do not move relative to the cylindrical member 18 provided with the atmospheric valve seat 21 and the rod member 55 abutting on the cylindrical member 18, the movable contact 56a of the microswitch 56 does not break. . On the other hand, when the solenoid 16 is excited by the control device and the tandem brake booster 1 is operated as an automatic brake, the tubular member 18 is moved to the front side with respect to the valve plunger 22 and the input shaft 35. Accordingly, the rod member 55 is also connected to the input shaft 3
5 is moved to the front side. Thereby, the movable contact 56a of the micro switch 56 is turned off. This makes it possible to detect that the tandem brake booster has been operated as an automatic brake.

(Description of Operation) In the above configuration, as shown in FIG. 1, when the solenoid 16 is not energized and the brake pedal (not shown) is not depressed, the valve plunger 22 is in the shell state. 2 wall 2a
And is held at the non-operating position by engaging with the key member 37 that has come into contact with the key member 37. Also, the flange portion 22e of the valve plunger 22
Abuts against the end face of the stepped portion of the cylindrical member 18 and the valve plunger 22
Is in contact with the plunger plate 43. Further, the atmosphere valve seat 21 provided on the cylindrical member 18 is seated on the second seat portion S2 of the valve body 24 to close the atmosphere valve 28, and the first seat portion S1 of the valve body 24 is separated from the vacuum valve seat 17. Then, the vacuum valve 25 is opened. Further, the engaging portion 48b of the piston 48 and the front end (locking portion) of the tubular member 18 are engaged, and the piston 48 is
1 is located at the rearward retreat end with respect to the piston 4
8 and a housing 4 opposed thereto.
A gap is maintained between the end face of the step. A slight gap is maintained between the front end surface of the plunger plate 43 (the end surface of the projection of the columnar member 43A) and the rear end surface of the reaction disk 44. As described above, since the vacuum valve 25 is open and the atmosphere valve 28 is closed, the chambers A, B, C, and D communicate with each other,
Negative pressure is introduced into them. Further, the front end of the rod member 55 is in contact with the radial portion 18D of the tubular member 18, and the rear end of the rod member 55 is in contact with the movable contact 56a of the microswitch 56. I have. When a brake pedal (not shown) is depressed from this non-operation state, the input shaft 35, the valve plunger 22, and the tubular member 18 are integrally advanced toward the front side. As a result, the second seat portion S2 of the valve body 24 is separated from the atmosphere valve seat 21 to open the atmosphere valve 28, and the first seat portion S1 of the valve body 24 is seated on the vacuum valve seat 17 and the vacuum valve is opened. 25 is closed. Therefore, the communication between the two constant pressure chambers A, C and the two transformation chambers B, D is prevented, and the atmosphere is introduced into the two transformation chambers B, D. The power pistons 11, 12 and the valve body 6, etc., are advanced toward the front side by the differential pressure between the negative pressure in both the constant pressure chambers A, C and the atmospheric pressure between the two variable pressure chambers B, D. The tandem brake booster 1 is operated in this manner, but the reaction force of the output acting on the output shaft 45 causes the shaft of the reaction disc 52 to bulge rearward, and the reaction disc 52 comes into contact with the plate plunger 43. Touch Therefore, from this point on, the output shaft 45
The reaction force of the output acting on the valve plunger 22 and the input shaft 3
5 to the driver. When the driver releases the brake pedal from this operating state, the return spring 47 returns the valve body 6 and the like to the original non-operating state shown in FIG. The normal operation of the tandem brake booster 1 when the brake pedal is depressed has been described above. In other words, solenoid 1
6 is not excited, the cylindrical member 18 is
Since the rod member 55 is not moved to the front side with respect to the input shaft 35, the rod member 55 is not moved to the front side with respect to the input shaft 35. Therefore, the movable contact 56a of the micro switch 56 does not swing, and the movable contact 56a does not break. That is, the detecting means 54 does not detect that the tandem brake booster 1 has operated as an automatic brake.

(Explanation of the operation as an automatic brake) When the tandem brake booster 1 is operated as an automatic brake in contrast to the above-mentioned normal operation, the brake pedal is not depressed and the non-operation state shown in FIG. Then, the solenoid 16 is excited by the control device. This allows
The piston 48 is moved to the front side with respect to the housing 41, and accordingly, the tubular member 18 is moved to the front side with respect to the valve body 6 and the valve plunger 22. As a result, the atmosphere valve seat 21 is separated from the second seat portion S2 of the valve body 24 to open the atmosphere valve 28, and the first seat portion S1 of the valve body 24 is seated on the vacuum valve seat 17. The vacuum valve 25 is closed. Therefore, the atmosphere is introduced into both the transformation chambers B and D, and the power pistons 11 and 1 are introduced.
2 and the valve body 6 are advanced toward the front side. In this way, the tandem brake booster 1 is operated as an automatic brake. However, as described above, the rod member 55 is also moved to the input shaft by moving the tubular member 18 toward the front side with respect to the valve plunger 22. 35 is moved to the front side. Therefore, the movable contact 56a of the micro switch 56 is swung toward the front side, and the movable contact 56a of the micro switch 56 is turned off. Thereby, the detecting means 54 can reliably detect that the tandem brake booster 1 is operated as an automatic brake. Detecting means 5
4 informs the control device that the tandem brake booster 1 has been operated as an automatic brake. When the operation of the solenoid 16 is stopped (deenergized) from the above operation state, the tubular member 18 is pushed back toward the rear side with respect to the valve plunger 22 by the springs 51 and 53, so that the atmosphere valve 28 is closed. Meanwhile, the vacuum valve 25 is opened. Therefore, the return spring 47 causes the valve body 6 and the like to return to the original non-operating state shown in FIG. 1, and the rod member 55 also returns to the original non-operating state shown in FIG. As described above, in this embodiment, the detection means 54 can reliably detect that the solenoid 16 has been operated and the tandem brake booster has been operated as an automatic brake. Further, since the detection means 54 is constituted by the rod member 55 and the microswitch 56, the installation space for the detection means 54 can be reduced, and the detection means 54 with high reliability can be provided. .

(Second Embodiment) FIG. 2 shows a second embodiment of the present invention. In the second embodiment,
The detecting means 5 includes a permanent magnet 61 and a magnetoelectric conversion element 62.
4. That is, in the second embodiment, while the rod member 55 and the microswitch 56 in the first embodiment are omitted, an annular permanent magnet is provided on the rear end surface of the valve plunger 22 (the rear end surface of the flange portion 22e). 61 is embedded, and a magnetoelectric conversion element 62 is attached to a radial portion 18 </ b> D of the cylindrical member 18 opposed to this. Other configurations are the same as those of the first embodiment. In the second embodiment, when the cylindrical member 18 is moved to the front side with respect to the valve plunger 22, the magnetic force of the permanent magnet 61 can be grasped by the magnetoelectric conversion element 62. Thus, when the solenoid 16 is excited and the tubular member 18 is moved with respect to the valve plunger 22, it is possible to reliably detect that the tandem brake booster has operated as an automatic brake. Since the permanent magnet 61 is formed in an annular shape, the detecting means 54 can operate normally even if the valve plunger 22 and the cylindrical member 18 move relative to each other in the circumferential direction. Further, a guide for preventing relative movement of the valve plunger 22 and the cylindrical member 18 in the circumferential direction may be provided so that the permanent magnet 61 is not annular. Further, in the second embodiment, the positions where the permanent magnets 61 and the magnetoelectric conversion elements 62 are provided may be reversed. Further, as long as one of the permanent magnet 61 and the magnetoelectric conversion element 62 is provided on the cylindrical member 18 and the other is provided on the valve plunger 22 so as to be opposed to each other, any location other than the location shown in FIG. Further, in each of the above-described embodiments, the case where the present invention is applied to the tandem brake booster has been described. The present invention can be applied to a triple type brake booster.

[0017]

As described above, according to the present invention, it is possible to reliably detect that the brake booster has been operated as an automatic brake.

[Brief description of the drawings]

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

FIG. 2 is a sectional view showing a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Tandem brake booster 6 Valve body 11 Front power piston 12 Rear power piston 16 Solenoid 17 Vacuum valve seat 21 Atmospheric valve seat 24 Valve body 25 Vacuum valve 28 Atmospheric valve 54 Detecting means 55 Rod member 56 Micro switch A, C Constant pressure chamber B, D Transformer room

Claims (3)

[Claims] 1. A substantially cylindrical valve body slidably provided in a shell, a power piston provided in the valve body, a constant pressure chamber and a variable pressure chamber defined before and after the power piston, and formed in the valve body. Annular vacuum valve seat,
A valve plunger movably provided in the valve body and interlocking with the input shaft, a tubular member slidably provided on an outer peripheral portion of the valve plunger, and an annular atmospheric valve seat formed on the tubular member. A vacuum which is urged toward the front side by a spring and comes into contact with and separates from the vacuum valve seat and the atmospheric valve seat, and a vacuum formed by the vacuum valve seat and a first seat portion of the valve body coming and going therefrom. An atmospheric valve constituted by a valve, the atmospheric valve seat, and a second seat portion of a valve element which comes into contact with and separates from the atmospheric valve seat; a constant pressure passage for communicating a space outside the vacuum valve with a constant pressure chamber; A variable pressure passage for communicating a space between the valve and the atmospheric valve with the variable pressure chamber, an atmospheric passage for communicating a space inside the atmospheric valve with the atmosphere, and a drive for moving the cylindrical member to an operating position. A brake booster having a mechanism Detecting means for detecting that the tubular member has been moved to the operating position when the tubular member is moved to the operating position by the mechanism and the vacuum valve seat is closed and the atmospheric valve is opened. A brake booster characterized by the following. 2. The detecting means comprises a rod member slidably fitted on the input shaft, and a microswitch mounted on an outer peripheral portion of the input shaft on a rear side of the rod member. 2. The brake according to claim 1, wherein a front end of the brake member contacts the cylindrical member, and a rear end of the rod member contacts a swingable movable contact of the microswitch. Booster. 3. The apparatus according to claim 1, wherein the detecting means comprises a magnet provided at one of the locations where the cylindrical member and the valve plunger face each other, and a magnetoelectric conversion element provided at the other. 4. The brake booster according to 4.