JPH0853061A - Automatic brake device - Google Patents

Abstract

PURPOSE:To obtain a small-sized solenoid by adjusting the flow passage of a variable orifice formed in the atmosphere passage of the first pressure chamber of a piston according to the magnitude of the magnetic force of the solenoid, installing an orifice in the negative pressure passage of the first pressure chamber, and obtaining the control pressure by introducing the atmosphere into the second pressure chamber by a valve mechanism. CONSTITUTION:Inside the second pressure chamber 52 between the first and the second pressure chambers 51 and 52 of the piston 42 of a control valve 24, the piston 42 is urged upwardly by a spring 53 and put into a nonoperative position. A valve body 57 is shifted upward by the magnetic force of a solenoid 43, and a variable orifice 59 is opened, and the atmosphere is introduced into the inside of the first pressure chamber 51. At this time, inside the first pressure chamber 51, a portion of the atmosphere is discharged into the first pressure chamber, because of the negative pressure due to an orifice 54, and the atmosphere is introduced into the first pressure chamber 51. The piston 42 is lowered by the differential pressure in the first and the second pressure chambers 51 and 52, and the atmosphere is introduced into a tandem brake booster device 1 through the second and the first passages 41b and 41a and a conduit 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic braking device, and more particularly to an automatic braking device composed of a brake booster and a control valve.

[0002]

2. Description of the Related Art Conventionally, an automatic brake device having the following structure is known. That is, a piston that is biased to a non-actuated position by a spring, a solenoid that, when excited, moves the piston in a direction opposite to the direction in which the spring biases the piston, and when control pressure is supplied. A pressure chamber that pushes back the piston toward the solenoid, and a control valve that includes a valve mechanism that generates a control pressure according to the urging force of the solenoid with respect to the piston and introduces the control pressure into the pressure chamber,
A brake device is known which is in communication with the pressure chamber of the control valve and includes a brake booster that generates a brake fluid pressure according to the control pressure without depressing the brake pedal when the solenoid is excited. (For example, JP-A-61-215156). In the conventional automatic brake device described above, the required control pressure is obtained by balancing the urging force of the solenoid acting on the piston with the urging force of the control pressure in the pressure chamber.

[0003]

However, in the above-mentioned conventional automatic brake device, the pressure receiving area of the piston cannot be made smaller than necessary, so that the piston must be controlled in order to counteract the control pressure in the pressure chamber acting on the piston. It was also necessary to increase the urging force of the solenoid against.
Therefore, the conventional brake device described above has a drawback that the solenoid becomes large.

[0004]

[Means for Solving the Problems] In view of such circumstances,
The present invention communicates with a control valve that generates a control pressure according to the magnitude of a magnetic force when a solenoid is excited, and communicates with the control valve. When the control pressure is introduced, the brake pedal is operated. In an automatic brake device equipped with a brake booster that generates a brake fluid pressure according to the magnitude of the control pressure without the control valve, the control valve is provided movably in the housing and is in an inoperative position by a spring. A biased piston, a first pressure chamber and a second pressure chamber formed before and after a pressure receiving portion of the piston, an atmosphere passage communicating the first pressure chamber with the atmosphere, and a variable orifice formed in the atmosphere passage. A solenoid that works in conjunction with the variable orifice to adjust the size of the flow path of the variable orifice according to the magnitude of the magnetic force when excited, and a negative pressure in the first pressure chamber. In conjunction with the negative pressure passage for communicating, an orifice formed in the negative pressure passage, and the piston,
And a valve mechanism for switching the communication state of the fluid passage in the housing to introduce the atmosphere into the second pressure chamber to obtain the control pressure.

[0005]

According to such a structure of the control valve, the pressure of the first pressure chamber is adjusted by changing the size of the flow path of the variable orifice according to the magnitude of the magnetic force when the solenoid is excited. be able to. Then, it is possible to obtain the control pressure in the second pressure chamber according to the magnitude of the pressure in the first pressure chamber. In other words, the magnetic force required to excite the solenoid to obtain the required control pressure may be the small magnetic force required to operate the variable orifice. Therefore, the solenoid can be made smaller than the conventional device.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. In FIGS. 1 and 2, reference numeral 1 is a tandem brake booster having a center plate 3 inside a shell 2.
It is divided into two rooms, a front room 4 and a rear room 5, which are located in front of and behind it. Then, the wall 2A on the rear side of the shell 2
The cylindrical valve body 6 is slidably pierced through the opening of the center plate 3 and the shaft portion of the center plate 3 with sealing means kept airtight. A front power piston 7 and a rear power piston 8 are connected to the outer peripheral portions of the valve bodies 6 located in the front chamber 4 and the rear chamber 5, respectively, and a front diaphragm 11 is provided on the back surface of each power piston 7, 8. And the rear diaphragm 12 are stretched. A constant pressure chamber A and a variable pressure chamber B are formed before and after the front diaphragm 11, and a constant pressure chamber C and a variable pressure chamber D are also formed before and after the rear diaphragm 12. A bellows 13 is disposed in the constant pressure chamber A, and the rear end of the bellows 13 is connected to the outer circumference of the front end of the valve body 6 while maintaining airtightness. The end portion is connected to the front wall surface 2B of the shell 2 by the support member 9. Then, the inside of the constant pressure chamber A is bellows 13 by this bellows 13.
It is divided into a bellows chamber A'which is an internal space of the above and a space on the outer side thereof. In the valve body 6, the constant pressure chamber A,
Valve mechanism 14 for switching the communication state between C and the variable pressure chambers B and D
Is provided. The valve mechanism 14 is formed on an annular first valve seat 15 formed on the valve body 6 and a right end portion of a valve plunger 16 slidably provided on the valve body 6 inside the annular first valve seat 15. An annular second valve seat 17,
Further, both valve seats 15 and 17 are provided with a valve body 18 which is seated by a spring. A vacuum valve 21 is constituted by the first valve seat 15 and an annular seat portion of the valve body 18 which comes in contact with and separates from the first valve seat 15. A space on the outer peripheral side of the vacuum valve 21 is a first constant pressure passage formed in the valve body 6. It communicates with the bellows chamber A ′ via 22. The bellows chamber A ′ has a conduit 23
It is connected to a control valve 24, which will be described in detail later, via the control valve 24 so that a negative pressure or atmosphere can be selectively introduced into the bellows chamber A ′. Further, the inside of the constant pressure chamber A, which is on the outer side of the bellows chamber A ', is always in communication with the negative pressure source via the conduit 25. Therefore, in the constant pressure chamber A on the outer side of the bellows chamber A', Negative pressure is always introduced. The inside of the constant pressure chamber A, which is outside the bellows chamber A ′, is always in communication with the constant pressure chamber C via a second constant pressure passage 26 provided at a position outside and adjacent to the outer peripheral bead portion 11a of the front diaphragm 11. A negative pressure is always introduced into the constant pressure chamber A and the constant pressure chamber C outside the bellows chamber A ′. On the other hand, a space on the inner peripheral side of the vacuum valve 21 and on the outer peripheral side of the atmosphere valve 27 constituted by the second valve seat 17 and the annular seat portion of the valve body 18 coming into contact with and separated from the second valve seat 17 is formed in the valve body 6. It communicates with the variable pressure chamber D through a first variable pressure passage 31 in the radial direction, and this variable pressure chamber D is changed through a second variable pressure passage 32 formed in the valve body 6 to the variable pressure chamber B.
Is in communication with. Further, the space on the inner peripheral side of the atmosphere valve 27 is communicated with the atmosphere via an atmosphere passage 33 formed by the inner peripheral surface of the valve body 6 and a filter 34 provided therein. The right end of the valve plunger 16 is connected to an input shaft 35 that is linked to a brake pedal (not shown), and the left end of the valve plunger 16 faces a reaction disc 37 housed in the base of the output shaft 36. The left end of the output shaft 36 penetrates the opening of the wall surface 2B of the shell 2 and is linked to the piston of the master cylinder (not shown). The valve body 6 and the wall surface 2B of the shell 2
A return spring 38 is elastically mounted on the valve body 6 and the valve body 6 so that the valve body 6 can be returned to the inoperative position in the drawing. Next, as shown in FIG. 1, the control valve 24 of the present embodiment is formed in the housing 41 and a piston 42 slidably provided in a hole 41A of the housing 41, a solenoid 43 interlocking with the piston 42. And a valve mechanism 44 for switching the communication state of the fluid passage to generate a control pressure according to the magnetic force of the solenoid 43. One end of the conduit 23 is connected to the first passage 41a provided in the housing 41.
A first valve seat 42a formed at the lower end of the piston 42 is interposed in the la 1a. The first passage 41a is connected to the second passage 41b, and the atmosphere is constantly introduced into the second passage 41b. The first passage 41a and the second passage 4
An annular second valve seat 41c is formed at the connecting portion with 1b, and the first valve seat 42a and the second valve seat 41c are provided with a valve element 46 biased upward by a spring 45.
Are facing each other. The internal space of the valve body 46 communicates with the inside of the constant pressure chamber A on the outer side of the bellows chamber A ′ via the hole 41d of the housing 41 and the conduit 47 connected to the hole 41d, and therefore, the valve body Negative pressure is always introduced into the internal space of 46. Further, in the non-illustrated operating state, the valve body 46 is seated on the second valve seat 41c while the first valve seat 42 is seated.
It is separated from a. Therefore, the conduit 47, the hole 41d of the housing 41, the internal space of the valve body 46, the first passage 41a
Negative pressure is also introduced into the bellows chamber A ′ of the tandem brake booster 1 via the conduit 23. Further, in the non-actuated tandem brake booster 1, the vacuum valve 21 is open and the atmosphere valve 27 is closed as is conventionally known, so that all the chambers A and B in the shell 2 are closed. ，
Negative pressure is introduced into C and D. Therefore, when the brake pedal (not shown) is depressed from this inoperative state, the atmospheric valve 27 is opened and the vacuum valve 21 is closed, so that the constant pressure chambers A and C and the variable pressure chambers B and D are closed. A differential pressure is generated, and as is well known, a tandem brake booster 1
Is activated to generate a brake fluid pressure corresponding to the pedal effort of the brake pedal. Next, a pressure receiving portion 42b formed of a large-diameter flange is formed at a predetermined position on the outer peripheral portion of the piston 42 in the control valve 24.
A diaphragm 48 is stretched over 2b and the inner peripheral surface of the hole 41A of the housing. As a result, the pressure receiving portion 4
A first pressure chamber 51 and a second pressure chamber 52 are formed above and below 2b. A spring 53 is elastically mounted in the second pressure chamber 52 to urge the piston 42 upward. Therefore, in a non-illustrated non-operating state where the solenoid 43 is not excited, the piston 42 is The end surface 42c is stopped at a non-operating position where it comes into contact with the end surface 41e of the hole 41A of the housing 41. Therefore, as described above, the valve body 46 of the valve mechanism 44 is seated on the second valve seat 41c and is separated from the first valve seat 42a, and is located in the bellows chamber A ′ of the tandem brake booster 1. Negative pressure is introduced. A circular recess 42d is formed in the center of the end surface 42c of the piston 42, and a notch 42e is formed continuously from the recess 42d to the outer peripheral surface. Further, the second pressure chamber 52 is communicated with the first passage 41a by the communication hole 41f of the housing 41. Therefore, the second pressure chamber 52 is formed by the communication hole 41f and the first passage 4a.
It is in constant communication with the bellows chamber A ′ via 1a and the conduit 23. Therefore, as will be described later, when the control pressure is generated by introducing the atmosphere into the second pressure chamber 52, the control pressure is also introduced into the bellows chamber A ′. On the other hand, the first pressure chamber 51 has an orifice 54 formed by a stepped through hole formed in the housing 41,
It is connected to the conduit 25 via a conduit 55 connected to this orifice 54, so that these conduits 25,
A predetermined negative pressure is always introduced into the first pressure chamber 51 via 55 and the orifice 54. In addition, the orifice 5
4 may be provided in the conduit 55 instead of being provided in the housing 41. Further, a taper hole 41g as an air passage whose diameter is reduced on the lower side is formed at a position in the housing 41 facing the recess 42d of the piston 42, and the outside of the housing 41 covers the taper hole 41g. And the casing 43A of the solenoid 43 is connected. The taper hole 4 is provided at a required position of the casing 43A.
The atmosphere passage 56 is formed by a notch penetrating from a position directly above 1 g to the outer peripheral portion in the radial direction. Therefore, in the first pressure chamber 51, the atmosphere passage 56 and the taper hole 41 g as the atmosphere passage are formed. The atmosphere can be introduced via and. A guide hole 43 having a bottom is provided in the shaft portion of the solenoid 43 which is located immediately above the tapered hole 41g.
A is formed, and a rod-shaped valve member 57 is slidably fitted in the tapered hole 41g. The lower end portion of the valve member 57 is a tapered portion 57a whose lower side is reduced in diameter in accordance with the size of the tapered hole 41g, while between the upper end of the valve member 57 and the bottom portion of the guide hole 43a. , Spring 5
8 is mounted so that the entire valve member 57 is constantly pushed downward. The valve member 57 is a magnetic body, and the solenoid 43
In the non-actuated state in which the magnet is not excited, it is pushed down by the spring 58, so that the tapered portion 57a is pressed against the tapered hole 41g to completely close the tapered hole 41g. The solenoid 43 is energized by supplying a required current by a control device (not shown), and the energized solenoid 43 springs the valve member 57 by a magnetic force corresponding to the magnitude of the applied current. It can be moved upwards against 58. Therefore, in that case, the atmosphere can be introduced into the second pressure chamber 52 through the gap between the tapered hole 41g and the tapered portion 57a. As described above, in this embodiment, the variable orifice 59 is configured by the tapered hole 41g of the housing 41 and the tapered portion 57a of the valve body 57 for adjusting the size of the flow passage. In the above configuration, when the tandem brake booster 1 is operated as an automatic brake device, a required current is applied to the solenoid 43 by the control device from the inoperative state shown in the figure. This allows
Since the solenoid 43 is excited to generate a magnetic force according to the magnitude of the applied current, the valve body 57 is attracted by the magnetic force and moved upward against the spring 58. Therefore, the flow path of the variable orifice 59 is opened by an amount corresponding to the magnetic force of the solenoid 43.
The atmosphere is introduced into the first pressure chamber 51 via the. At this time, since a predetermined negative pressure is introduced into the first pressure chamber 51 via the orifice 54, a part of the atmosphere introduced into the first pressure chamber 51 via the variable orifice 59 is introduced. The first pressure chamber 5 through the orifice 54 and the conduits 55, 25.
Therefore, the atmosphere having a pressure corresponding to the magnetic force of the solenoid 43 is introduced into the first pressure chamber 51. When the atmosphere is introduced into the first pressure chamber 51 in this way, a differential pressure is generated between the atmosphere in the first pressure chamber 51 and the negative pressure in the second pressure chamber 52, and the spring 53 is compressed by the differential pressure. Meanwhile, the piston 42 is lowered. As a result, the valve element 46 is seated on the first valve seat 42a and the second valve seat 4
Since it is separated from 1c, the second passage 41b, the first passage 41
tandem brake booster 1 via a and conduit 23
Atmosphere is introduced into the bellows chamber A ′. The atmosphere introduced into the bellows chamber A ′ is introduced into the variable pressure chambers B and D through the first constant pressure passage 22, the vacuum valve 21 in the open state, and the variable pressure passages 31 and 32. As a result, the tandem brake booster 1 can be operated without stepping on the brake pedal to obtain a function as an automatic brake device. In this way, when the solenoid 43 is excited and the automatic brake device is operated, the atmosphere is also introduced into the second pressure chamber 52 through the communication hole 41f. Therefore, the pressure of the first pressure chamber 51 acts on the pressure receiving portion 42b of the piston 42 so as to push it down, and at the same time, the atmospheric pressure of the second pressure chamber 52 acts on the pressure receiving portion 42b. Then, the piston 42 stops at a position where the pressures in the pressure chambers 51 and 52 acting on the pressure receiving portions 42b are balanced. At this point, the valve element 46 has the two valve seats 42.
Since the seats a and 41c are seated at the same time, the introduction of the atmosphere into the bellows chamber A'is stopped. In this way, the valve mechanism 44
Generates an atmosphere (control pressure) having a pressure corresponding to the magnitude of the magnetic force when the solenoid 43 is excited, in the second pressure chamber 52, and supplies the control pressure to the bellows chamber A ′ of the tandem brake booster 1. It is possible to introduce it. Therefore, as described above, the tandem brake booster 1 can be operated without depressing the brake pedal to function as an automatic brake device. As described above, in the present embodiment, when the solenoid 43 of the control valve 24 is excited, the magnitude of the magnetic force of the solenoid 43 is determined by the spring 5
A small magnetic force that can move the valve body 57 upward by a required amount against 8 is sufficient. Therefore, according to this embodiment, a small solenoid can be adopted as the solenoid 43 of the control valve 24. Note that the present invention can be applied to a single type booster having a pair of constant pressure chambers and a variable pressure chamber in the shell 2 instead of the tandem brake booster 1 in the above embodiment.

[0007]

As described above, according to the present invention, the effect that the solenoid of the control valve can be downsized can be obtained.

[Brief description of drawings]

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

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

[Explanation of symbols]

1 Tandem Brake Booster 24 Control Valve 41 Housing 42 Piston 43 Solenoid 44 Valve Mechanism 51 First Pressure Chamber 52 Second Pressure Chamber 53 Spring 54 Orifice 59 Variable Orifice

Claims (1)

[Claims] 1. A control valve for generating a control pressure according to the magnitude of a magnetic force when a solenoid is excited is communicated with the control valve, and a brake pedal is operated when the control pressure is introduced. And a brake booster that generates a brake fluid pressure according to the magnitude of the control pressure without performing the control valve, the control valve being provided movably in the housing and being in an inoperative position by a spring. And a first piston formed before and after the pressure receiving portion of the piston.
The pressure chamber and the second pressure chamber, the atmosphere passage for communicating the first pressure chamber with the atmosphere, the variable orifice formed in the atmosphere passage, and the variable orifice in conjunction with each other to adjust the magnitude of the magnetic force when excited. A solenoid for adjusting the size of the flow path of the variable orifice according to the negative pressure passage, a negative pressure passage for communicating the first pressure chamber with a negative pressure source, an orifice formed in the negative pressure passage, the piston, and the housing. An automatic brake device comprising: a valve mechanism that switches the communication state of a fluid passage therein to introduce atmospheric air into the second pressure chamber to obtain the control pressure.