JPS6212453A - Suction pressure type booster - Google Patents

Abstract

PURPOSE:To improve an operation feeling so high, by lessening an atmospheric intake into an operating chamber at the atmospheric intake side to be partitioned off by a diaphragm inside a booster shell with a throttle valve gear at the input initial stage of an input rod, and avoiding a sudden advance of a booster piston. CONSTITUTION:At the time of braking a car, if a brake pedal 37 is operated, a valve piston 12 advances forward via an input rod 11, and a valve part 13c being energized by a valve spring 16 in the wake of this piston advancement also goes forward, taking a first valve seat 101, and cuts off the interconnection between both operating chambers A and B. Simultaneously a second valve seat 102 comes off the valve part 13c, having the second operating chamber B interconnected to an atmospheric intake port 6. At this time, since a throttle valve 45 of a throttle valve gear V accords with an opening part of a through hole 18 and throttles the opening an atmospheric intake into the second operating chamber B is lessened. And, when input into the input rod 11 is increased, the throttle valve 45 reaches to a position slipping off from the opening part of the through hole 18, opening the through hole 18 free, so that the atmospheric intake into the second operating chamber chamber B is increased.

Description

Detailed Description of the Invention A0 Object of the Invention (1) Industrial Field of Application The present invention relates to a negative pressure booster used for operating a brake mask cylinder, in particular, to a booster shell that has a back and forth reciprocating motion. The booster piston is divided into a first working chamber communicated with a negative pressure source by a freely housed booster piston, and a second working chamber whose communication with the first working chamber or the atmosphere is switched and controlled via a control valve. The present invention relates to an improvement in which the input rod is connected to the control valve so that when the input rod, which is movably connected to the piston, moves forward, a pressure difference is generated between the two working chambers for causing the booster piston to follow the movement.

(2) Prior Art Conventionally, the booster does not have a means for adjusting the amount of atmospheric air introduced into the second working chamber.

(3) Problems to be Solved by the Invention In order to improve the operating feeling of the booster, it is necessary to reduce the amount of air introduced into the second working chamber at the initial stage of input from the input rod so that the booster piston On the other hand, when the input to the input rod increases beyond a certain amount, it may be possible to increase the amount of air introduced into the second working chamber to smoothly advance the booster piston. However, such consideration has not been taken in the conventional device.

In view of the above, an object of the present invention is to provide the booster which can improve the operating feeling by adjusting the amount of air introduced into the second working chamber using extremely simple means.

B6 Structure of the Invention (1) Means for Solving the Problems The present invention provides for the booster piston to be provided with the second
The control valve is provided with a throttle valve device for a through hole that communicates between the working chamber and the control valve, and the throttle valve device opens the through hole when the input rod is retracted, and when the input rod is initially input to the input rod. The device is characterized in that the same passage hole is narrowed, and the same passage hole is opened in accordance with a subsequent increase in the input to the input rod.

(2) At the initial stage of input to the action input rod, the throttle valve device restricts the through hole and reduces the amount of air introduced into the second working chamber.
Rapid advancement of the booster piston is avoided. Thereafter, when the input to the input rod increases, the throttle valve device opens the through hole accordingly, increasing the amount of atmospheric air introduced into the second working chamber, so that the booster piston moves forward smoothly. on the other hand,
When the input rod is retracted, the through hole is opened by the throttle valve device, so the two working chambers communicate with each other, eliminating the pressure difference between them, and the booster piston retracts smoothly.

(3) Embodiment The illustrated example shows a case where the present invention is applied to a negative pressure type booster for operating a brake mask cylinder.

The booster shell 1 of the negative pressure booster S is formed by butting together a pair of front and rear bowl-shaped bodies IF and IR formed from steel plates. The booster piston 2 is freely accommodated, and an annular groove 2a is formed on the rear surface of the booster piston 2.

There are annular beads on the outer and inner periphery of the diaphragm 3)-3a
, 3b are formed respectively, and the annular bead 3a on the outer periphery is sandwiched between the bowl-shaped bodies IF and IR, and the annular bead 3b on the inner periphery is fitted into the annular groove 2a of the booster histone 2. *The interior of the booster shell 1 is divided by the booster piston 2 and the diaphragm 3 into a first working chamber A at the front and a second working chamber B at the rear.

The pressure receiving portion 3c of the diaphragm 3 is in close contact with the rear surface of the booster piston 2 and protrudes toward the first working chamber A between the outer circumferential surface of the booster piston 2 and the inner circumferential surface of the front bowl-shaped body IF. It is bent into a U-shape and allows the booster piston 2 to move forward and backward by shifting the U-shaped bent portion.

The first working chamber A is constantly in communication with an intake manifold (not shown) of the internal combustion engine, which is a negative pressure source, through a negative pressure introduction pipe 4.
The second working chamber B is connected to the first working chamber A via a control valve 5 which will be described later.
Alternatively, the atmosphere inlet 6 opened in the end wall 1b of the rear extension tube 1a of the booster shell 1, and thus communication with the atmosphere, is switched and controlled.

The booster piston 2 is always urged in the backward direction, that is, toward the second working chamber B, by a return spring 7 contracted in the first working chamber A, and its backward limit is reached by a protrusion 3d formed protrudingly on the back surface of the diaphragm 3. It is regulated by coming into contact with the inner surface of the rear wall of the shell 1.

The booster piston 2 has a valve cylinder 8 that protrudes in the axial direction from the rear surface of its center, and is connected to the flat bearing 9 of the extension cylinder 1a.
The rear end face is opened toward the atmosphere inlet 6.

The control valve 5 is configured in the valve cylinder 8 as follows.

That is, an annular first valve seat 10° is formed on the inner wall of the front part of the valve cylinder 8, and an input rod 11 inserted into the valve cylinder 8 is formed in the front part of the valve cylinder 8.
A valve piston 12 connected to the front end of the valve piston 10 is slidably connected to the rear end of the first valve seat 10. An annular second valve seat 10□ is formed surrounded by the second valve seat 10□.

A base end 13a of a cylindrical valve body 13 that surrounds the middle part of the input rod 11 and has both end faces open is sandwiched between the inner wall of the valve cylinder 8 and a valve body holding cylinder 14 that is fitted into the valve cylinder 8. Stop. This valve body 13
is made of an elastic material such as rubber, and its base end 1
A thin-walled diaphragm 13b extends radially inward from the diaphragm 3a, and a thick-walled valve portion 13c is connected to the inner circumferential end of the thin-walled diaphragm 13b, which is connected to the first and second valve seats 10. ．． 1
Face 0□. Therefore, the valve portion 13C is the diaphragm 1.
3b can be moved back and forth by deformation, and the valve body holding cylinder 1
It can also come into contact with the front end surface of No. 4.

An annular reinforcing plate 15 is embedded in the valve part 13c, and the valve part 1 is attached to the annular reinforcing plate 15.
3c toward both valve seats 10+ and 10z.

1st valve seat 10. The outer part of is the through hole 1 of the booster piston 2.
7 to the first working chamber A, and the first and second valve seats 1
0. ．． The middle part of 102 is connected to the second working chamber B through the inside of the valve cylinder 8 and the through hole 18 in the peripheral wall of the valve cylinder 8, and to the second valve seat 10z.
The inner parts of the valve body 13 are in constant communication with the atmospheric air inlet 6 through the inside of the valve body 13.

The booster piston 2 is provided with a large-diameter hole 19 that opens at the center of its front surface and a small-diameter hole 20 that opens at the inner end of the large-diameter hole 19. An elastic piston 21 and an output piston 22 having the same diameter are sequentially slid together, a reaction piston 23 having a smaller diameter than the elastic piston 21 is slid into the small diameter hole 20, and a small shaft at the front end of the valve piston 12 is inserted into the small diameter hole 20. The portion 1.2b is pushed in to face the rear end surface of the reaction piston 23.

The output piston 22 integrally has an output rod 22a that projects forward.

The input rod 11 is always urged in the backward direction by the return spring 24, and its retreat limit is reached when the movable stopper plate 25 screwed onto the input rod 11 comes into contact with the inside of the end wall 1b of the rear extension tube 1a. regulated by. Therefore, the movable stopper plate 2
By rotating 5, the screwing position between it and the input rod 11 changes, so the retraction limit of the input rod 11 can be adjusted back and forth. After the adjustment, the movable stopper plate 25 is fixed by tightening a lock nut 26 which is also screwed onto the input rod 11. A vent hole 27 is bored in the movable stopper plate 25 so that the movable stopper plate 25 does not block the air inlet 6.

Filters 28 and 29 are attached to the outer end opening of the valve cylinder 8 to purify the air introduced from the atmospheric air inlet 6 and to be deformable so as not to interfere with the operation of the input rod 11.

A mounting bolt 31 protruding from the front wall of the booster shell I is passed through the mounting flange 30 of the brake mask cylinder M, and a nut 32 is screwed onto the tip thereof and tightened. Further, a mounting bolt 33 protruding from the rear wall of the booster shell l passes through the front wall W of the vehicle compartment, and a nut 34 is screwed and tightened onto the tip thereof.

In the vehicle interior, at the rear end of the input rod 11 of the booster S, there is a brake pedal 37 that is pivotally supported 36 on a fixed bracket 35.
are connected via a connecting fitting 38.

39 is a return spring that urges the brake pedal 37 rearward.

The 4° rear end of the cylinder body of the brake mask cylinder M is fitted into a cylindrical recess 46 on the front wall of the booster shell 1, and a double plate is inserted into the rear end of the actuating piston 41 in the cylinder body 40, passing through the bottom surface of the recess 46. The output rods 22a of the force device S are opposed to each other.

The valve piston 12 has a first. As clearly shown in FIG. 4, a piston portion 12a that slides into the valve cylinder 8 on the front side of the opening of the through hole 18, and the small shaft portion 12b that protrudes from the front end surface of the piston portion 12a. , piston part 12
The connecting cylinder part 12C is provided with the second valve seat 10□, which is protruded from the rear end surface of the valve a.

The small shaft portion 12b has a right-handed multi-start thread 42 on its outer peripheral surface, and the multi-start thread 42 is screwed into a screw hole 43 formed in the front end wall of the valve barrel 8 and opening into the small diameter hole 20. Further, the connecting cylinder portion 12c is connected to the input rod 11 so as to be rotatable and immovable in the axial direction.

When the input rod 11 moves forward, the valve piston 12 moves forward and rotates forward via the screw mechanism 44 consisting of the multi-thread screw 42 and the threaded hole 43.On the other hand, when the input rod 11 moves backward,
The valve piston 12 is retracted and reversed via the helical mechanism 44.

A throttle piece 45 is provided protrudingly on the rear end surface of the piston portion 12a, and the throttle piece 45 opens the through hole 18 when the input rod 11 retreats, throttles the through hole 18 at the initial stage of input to the input rod 11, and then The through hole 18 is opened as the input to the input rod 11 increases.

Thus, the screw mechanism 44 and the throttle piece 45 are connected to the through hole 1.
A throttle valve device V is configured to adjust the opening degree of 8.

Next, to explain the operation of this embodiment, the state shown in FIG. 1 shows the non-operating state of the booster;
7 is returned to a predetermined retracted position where the movable stopper plate 25 abuts the fixed end wall 1b and is held by the spring force of the spring 24, and the valve piston 12 is moved to the front surface of the valve portion 13c via the second valve seat 10□. is pushed back until it lightly contacts the front surface of the valve body holding cylinder 14, thereby forming a slight gap g+ between the first valve seat lO1 and the valve portion 13c. Further, a predetermined gap g2 is formed between the front end surface of the piston portion 12a of the valve piston 12 and the rear surface of the front end wall of the valve cylinder 8, and a gap g3 smaller than the gap g2 is formed between the reaction piston 23 and the small shaft portion 12b. Ru. Throttle piece 4 of valve piston 12
5 is in a position completely out of the opening of the through hole 18, as shown in FIG. 1A. Such a state can be easily obtained by adjusting the movable stopper plate 25 described above.

As described above, during engine operation, the first working chamber A, which always stores negative pressure, communicates with the second working chamber B through the through hole 17, the gap g, and the through hole 18, and the front opening of the valve portion 13c. The part is the second valve seat 10. , so the second working chamber B
The negative pressure of the first working chamber A is transmitted to the re-working chambers A and H, so that the air pressures of the re-working chambers A and H are balanced. Therefore, the booster piston 2 also occupies the illustrated retracted position by the elastic force of the return spring 7.

Now, step on the brake pedal 37 to brake the vehicle,
When the input rod 11 is moved forward, the valve piston 12 moves forward and rotates in the normal direction. Further, the valve portion 13c, which is urged forward by the valve spring 16, moves forward following the valve piston 12, but since the gap g+ between the first valve seat lO0 and the valve portion 13C is extremely narrow as described above, the input At the initial stage of input to the rod 11, the valve part 1
3C, the first valve seat 10. Seated in the reactivation chamber A,
Cut off communication between B. At the same time, the second valve seat 10
3, the atmosphere is introduced into the second working chamber B.

In this case, the second valve piston 12 moves forward and rotates forward.
As shown in FIG. 2A, the throttle piece 45 matches the opening of the through hole 18 and narrows its opening, so the amount of air introduced into the second working chamber B is reduced. It is possible to suppress rapid pressure increase, avoid rapid advancement of the booster piston 2, and improve the operational feeling.

When the input to the input rod 11 increases, the valve piston 12 moves forward and rotates in the normal direction, and the throttle piece 45 moves to the third position.
．． As shown in FIG. 3A, the position is completely removed from the opening of the through hole 18, and the through hole 18 is opened, so that the amount of air introduced into the second working chamber B increases. As a result, the second working chamber B
The booster piston 2 can be smoothly advanced by quickly increasing the pressure of the booster piston 2, and the operation feeling can be improved.

As the booster piston 2 moves forward, the elastic piston 21
Since the output rod 22a moves forward via the brake mask cylinder M, the actuating piston 41 of the brake mask cylinder M is driven forward and the vehicle is braked.

On the other hand, when the small shaft portion 12b of the valve piston 12 approaches the elastic piston 21 via the reaction piston 23 due to its advancement, the elastic piston 21 bulges and deforms toward the reaction piston 23 side due to the operational reaction force of the output rod 22a. A part of the reaction force is fed back to the brake pedal 37 side via the valve piston 12, so that the driver can sense the output of the output rod 22a, that is, the braking force.

Next, when the depression force on the brake pedal 37 is released, the reaction force applied to the valve piston 12 and the return spring 24 are
The input rod 11 retreats due to the elastic force, thereby seating the second valve seat 10□ on the valve portion 13c and
c is brought into contact with the front surface of the valve body holding cylinder 14, so that the valve part 13
c receives the retreating force of the input rod 11 and undergoes compressive deformation in the axial direction.

As a result, a larger gap than the original gap g is formed between the first valve seat 10+ and the valve portion 13C, and since the valve piston 12 is retracted and reversed, the throttle piece 45 is closed as shown in FIG. 1A. reaches a position outside the opening of the through hole 18,
Since the passage hole 18 is opened, the air pressures in the reactivation chambers A and B quickly equilibrate with each other through the large gap and the passage hole 18, and when the pressure difference between them disappears, the booster piston 2
is moved backward by the elastic force of the return spring 7, and the projection 3d of the piston diaphragm 3 comes into contact with the inner surface of the rear wall of the booster shell 1 and stops. Then, when the input rod 11 comes into contact with the end wall 1b, the valve part 13c is released from the retreating force of the input rod 11 and returns to its original shape, thereby narrowing the gap with the first valve seat 101 to the small gap gI again. be able to.

C0 Effects of the Invention According to the present invention, at the initial stage of input to the input rod, the through hole is throttled by the throttle valve device to reduce the amount of air introduced into the second working chamber to avoid rapid advancement of the booster piston. When the input to the input rod increases, the throttle valve device opens the through hole accordingly, increasing the amount of air introduced into the second working chamber and smoothly advancing the booster piston. The operating feeling of the booster can be improved during the increase process.

Furthermore, since the through hole is opened by the throttle valve device when the input rod is retracted, the two working chambers are communicated with each other, eliminating the pressure difference between them, and the booster piston can be retracted smoothly.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is an overall longitudinal sectional side view, FIG. 1A is an explanatory diagram showing the relationship between the through hole and the throttle piece in FIG. 1, and FIG. FIG. 3 is a vertical sectional side view of the main part showing the operating state, and FIGS. 2A and 3A are 2. FIG. 3 is an explanatory view showing the relationship between the through hole and the throttle piece, and FIG. 4 is a perspective view of the valve piston.

Claims (1)

[Claims] A first working chamber communicates with a negative pressure source by a booster piston housed inside the booster shell so as to be able to reciprocate back and forth, and a second working chamber whose communication with the first working chamber or the atmosphere is controlled via a control valve. The input rod is connected to the booster piston in such a manner that when the input rod, which is divided into a working chamber and is movably connected to the booster piston, moves forward, a pressure difference is generated between the two working chambers to cause the booster piston to follow the movement. In a negative pressure booster connected to a control valve, the control valve is provided with a throttle valve device for a through hole provided in the booster piston and communicating between the second working chamber and the control valve, the throttle valve device opens the through hole when the input rod is retracted;
A negative pressure booster characterized in that the through hole is narrowed at the initial stage of input to the input rod, and is opened in accordance with a subsequent increase in input to the input rod.