JPH0353959Y2 - - Google Patents

Description

[Detailed description of the invention] A. Purpose of the invention (1) Industrial application field This invention forms a negative pressure chamber and a working chamber on the front and rear sides of the booster piston housed in the booster shell, and In the boss part of the piston,
A valve cylinder is slidably supported on the rear wall of the booster shell, and a first port communicates the inside of the valve cylinder with a negative pressure chamber, and a second port communicates the inside of the valve cylinder with an operating chamber. The valve cylinder is provided with a first valve seat formed on the inner wall of the valve cylinder, a second valve seat formed at the rear end of the valve piston that is slidably fitted into the valve cylinder, and a second valve seat formed on the rear end of the valve piston that is slidably fitted into the valve cylinder. When it is seated on the first valve seat and separated from the second valve seat, the second port is communicated with the atmosphere, and when it is seated on the second valve seat, the first valve is seated. accommodating a control valve consisting of a valve body that communicates between the first and second ports when separated from the seat, and forming an annular groove in the middle part of the valve piston from which the open end of the second port faces;
The present invention relates to an improvement in a negative pressure booster in which a valve piston and a front end of an input rod fitted into the center thereof are connected by caulking the bottom wall of the annular groove.

(2) Conventional technology Such a negative pressure booster is, for example,
This is already known as disclosed in Japanese Patent No. 121160.

In such a negative pressure booster, the reason why the annular groove is formed on the outer periphery of the intermediate portion of the valve piston is to reduce the wall thickness of the joint portion of the valve piston with the input rod to facilitate caulking connection.

(3) Problems to be solved by the invention In such a negative pressure booster, when the input rod is moved forward, the valve body seats on the first valve seat and the second valve seat separates from the valve body. The port and the atmosphere are shut off, and the second port and the atmosphere are communicated, and the atmosphere that has passed through the second valve seat sequentially passes through the annular groove of the valve piston and the second port and flows into the working chamber on the rear side of the booster piston. However, the booster piston moves forward due to the pressure difference between this working chamber and the negative pressure chamber in front of the booster piston. In this case, when the air that has passed through the first valve seat flows to the second port through the annular groove of the valve piston, the air flow is sharply bent by the annular groove, resulting in severe turbulence of air. May produce wind noise.

An object of the present invention is to provide the negative pressure booster that can operate quietly without producing the above-mentioned wind noise.

B. Structure of the invention (1) Means for solving the problem In order to achieve the above object, the invention provides a tapered rectifier in which the outer diameter decreases toward the second valve seat in the annular groove in the middle part of the valve piston. It is characterized by fitting a member.

(2) Effect According to the above configuration, when the atmosphere that has passed through the second valve seat flows to the second port via the annular groove of the valve piston, the air is distributed within the annular groove by the outer circumferential tapered surface of the air rectifying member. Since it is smoothly guided outward, it can flow to the second port without causing turbulence, and no wind noise is generated.

(3) Embodiment An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, a brake master cylinder M operated by the booster B is attached to the front surface of a booster shell 1 of a tandem negative pressure booster B. As shown in FIG.

The booster shell 1 includes a pair of front and rear shell halves 1a, 1b whose opposite ends are connected to each other, and is sandwiched between the two shell halves 1a, 1b so that the inside of the booster shell 1 is divided into a front shell chamber 2 and a rear shell chamber. 3, and a partition wall plate 1c that partitions the rear shell half body 1b into
is supported by a vehicle body (not shown).

The front shell chamber 2 includes a front booster piston 4 accommodated therein so as to be able to reciprocate back and forth, and a front booster piston 4 which is superposed and bonded to the rear surface and sandwiched between the front shell half 1a and the partition wall plate 1c. The diaphragm 5 creates a front negative pressure chamber 2a on the front side and a front working chamber 2 on the rear side.
It is divided into b. The rear shell chamber 3 also includes a rear booster piston 6 housed therein so as to be able to reciprocate back and forth, and a rear diaphragm 7 which is superimposed on the rear surface and fixed between the shell halves 1a and 1b together with the partition wall plate 1c. Accordingly, it is divided into a rear negative pressure chamber 3a on the front side and a rear working chamber 3b on the rear side.

The front and rear booster pistons 4 and 6 are each formed into an annular shape by a steel plate, and these are connected to the partition wall plate 1c.
It is connected to both ends of a synthetic resin piston boss 10 as a boss portion which is slidably supported via a bush 8 and a seal member 9 as follows.

That is, the depth of the piston boss 10 is
A circular recess 11 reaching approximately half the length of 0 is formed on the front end surface, and a flange 12 is protruded from the rear end of the outer peripheral surface at a location slightly forward.
The circular recess 11 includes a front booster piston 4.
A connecting tube 1 with an end wall plate 13a connected to the inner peripheral end of the
3 are fitted together, and a presser plate 14 that cooperates with the flange 12 to clamp the rear booster piston 6 is superimposed on the rear end surface of the piston boss 10. The presser plate 14, the piston boss 10, and the end wall plate 13a are connected to a plurality of (three in the illustration) through bolts 15 surrounding the axis of the piston boss 10,
They are fixed to each other by a nut 16 screwed into them.

At this time, an annular retainer 17 is inserted between the front booster piston 4 and the front end surface of the piston boss 10 to cover the inner peripheral bead 5a of the front diaphragm 5 and the outer peripheral surface and rear surface of the inner peripheral bead 5a. is,
Furthermore, an inner peripheral bead 7a of a rear diaphragm 7 that surrounds the inner peripheral end of the rear booster piston 6 is inserted between the flange 12 and the presser plate 14. Therefore, at the same time that the front and rear booster pistons 4, 6 and the piston boss 10 are connected to each other,
Inner peripheral beads 5a, 7a of each diaphragm 5, 7 are fixed to corresponding booster pistons 4, 6.

Further, a sealing member 19 is attached to the bolt hole 18 provided in the piston boss 10 for insertion of the through bolt 15, so that the bolt hole 18
communication between the front negative pressure chamber 2a and the rear working chamber 3b is blocked. Further, a sealing member 20 surrounding the plurality of through bolts 15 is interposed between the end wall plate 13a and the piston boss 10, thereby sealing the contact surface between the end wall plate 13a and the piston boss 10. The first and second ports 30 and 31 described below by
communication between them is blocked.

Each through bolt 15 is arranged with its square head 15a facing the rear working chamber 3b side, and its square head 15
A recess 21 (see FIG. 2) of the same shape is formed in the presser plate 14, into which the recess 21 (see FIG. 2) is fitted non-rotatably. Therefore, when the nut 16 is passed through and screwed onto the bolt 15 on the front negative pressure chamber 2a side, the bolt 15 is prevented from rotating, so that the nut 16 can be tightened reliably.

The seat plate 22 is overlappingly bonded to the end wall plate 13a of the connecting cylinder 13 using the through bolts 15 and nuts 16. This seat plate 22 has a plurality of nuts 16
It is provided with a plurality of seats 22a (see FIG. 3) that are raised higher than the height of the nut 16 between them, and a return spring 23 is compressed between these seats 22a and the front shell half 1a. . The spring force of the return spring 23 always urges the piston boss 10 and therefore both booster pistons 4 and 6 in the backward direction. The backward limit of both booster pistons 4 and 6 is regulated by a large number of protrusions 24 raised on the rear surface of rear diaphragm 6 abutting against the rear wall of booster shell 1 .

The front negative pressure chamber 2a is connected to a negative pressure source (for example, inside an intake manifold of an internal combustion engine), which is not shown, via a negative pressure introduction pipe 29. Further, both the front and rear negative pressure chambers 2a, 3a communicate with the inside of the valve cylinder 25 via a bifurcated first port 30 formed in the piston boss 10, and both the front and rear working chambers 2b, 3b are connected in the same way. It communicates with the inside of the valve cylinder 25 via a pair of bifurcated second ports 31, 31 formed in the piston boss 10.
The second ports 31, 31 are alternately switched to communicate with the first port 30 and an atmosphere inlet 33 opened in the end wall 26a of the rear extension tube 26 by a control valve 32.

Inside the valve cylinder 25, an input rod 35 connected to the brake pedal 34 and the control valve 32 controlled by the input rod 35 are provided as follows. That is, a valve piston 38 is slid into the front portion of the valve cylinder 25, and an annular front end portion 35a of the input rod 35 passing through the air inlet port 33 is fitted into the center of the valve piston 38. On the outer periphery of the intermediate portion of the valve piston 38, the second
An annular groove 38a is formed that faces the open ends of the ports 31, 31, and by caulking the bottom wall of this annular groove 38a at several locations 60 (only one location is shown), the input rod 35 is attached to the valve piston 38. The spherical front end portion 35a of the holder is swingably connected to the spherical front end portion 35a of the holder.

Further, an annular first valve seat 4 is provided on the inner peripheral surface of the valve cylinder 25.
_An annular second valve seat 40 2 is formed on the rear end surface of the valve piston 38, and is surrounded by a second valve seat 40 ₂ that protrudes from the valve seat 40 1 .
A valve body 41 that cooperates with these valve seats 40 ₁ and 40 ₂ is disposed within the valve cylinder 25 . The valve body 41 is made of rubber and has a cylindrical shape with both front and rear ends open, and the rear end, that is, the base end 41a, is held by a holding cylinder 42 fitted to the inner circumferential surface of the valve cylinder 25. It is maintained in close contact with the inner peripheral surface of the cylinder 25. The valve body 41 includes a thin flexible portion 41b bent radially inward from the base end 41a, and a thick valve portion 41c continuous to the front end of the flexible portion 41b. 4
1c is arranged opposite to the first and second valve seats 40 ₁ and 40 ₂ .

The valve part 41c can be moved back and forth by deforming the flexible part 41b, and is seated on the first and second valve seats 40 ₁ and 40 ₂ when moving forward, and is received at the front end of the holding cylinder 42 when retreating. It can be stopped.

An annular reinforcing plate 43 is embedded in the valve portion 41c,
A valve spring 44 is compressed between this and the input rod 35 and urges the valve portion 41c toward both valve seats 40 ₁ and 40 ₂ .

On the inner surface of the valve cylinder 25, one end of the first port 30 is located outside the first valve seat 40 ₁ , and one end of the first port 30 is located outside the first valve seat 40 ₁ .
One end of each of the second ports 31, 31 opens inside the second port 31, 31, respectively.

Further, the inside of the second valve seat 40 ₂ communicates with the atmosphere inlet 33 through the hollow portion of the valve body 41 and the holding cylinder 42 .

Thus, the valve body 41, the valve spring 44, and the first valve seat 40
_{The first} and second valve seats 40 ₂ constitute the control valve 32 .

A tapered air rectifying member 61 whose outer diameter decreases toward the second valve seat 40 ₂ is fitted into the annular groove 38 a of the valve piston 38 . This air rectifying member 61 is made of rubber so that it can be deformed to expand its diameter in consideration of ease of attachment to the annular groove 38a. In addition, when it is made of a non-elastic material, it may be divided into two in the radial direction and attached to the annular groove 38a.

Further, the air rectifying member 61 is desirably formed such that its small diameter end has approximately the same diameter as the second valve seat 40 ₂ and its large diameter end has approximately the same diameter as the front end, ie, the sliding portion, of the valve piston 38 .

Between the input rod 35 and the holding cylinder 42, the input rod 35
A return spring 45 is provided that urges the return spring 45 toward its retraction limit.

The retraction limit of the input rod 35 is determined by a stopper plate 46 that is screwed to the input rod 35 so as to be able to move forward and backward.
It is regulated by contacting the inner surface of the end wall 26a. Therefore, by rotating the stopper plate 46, the screwing position between the stopper plate 46 and the input rod 35 changes, so that the retraction limit of the input rod 35 can be adjusted back and forth. The fixing of the stopper plate 46 after this adjustment is as follows:
This is done by tightening a lock nut 47 which is similarly screwed onto the input rod 35. The stopper plate 46 includes
A ventilation hole 48 is provided to prevent this from blocking the air inlet 33.

The valve cylinder 25 is provided with an air filter 4 for filtering air taken into the valve cylinder 25 from the atmosphere inlet 33.
9 is attached to surround the input rod 35. This air filter 49 has appropriate flexibility so as not to impede relative displacement between the input rod 35 and the valve cylinder 25.

The piston boss 10 has a large cylinder hole 37 that opens at the center of its front surface, and a large cylinder hole 37 that opens at the center of the front surface.
and a small cylinder hole 3 whose both ends are open inside the valve cylinder 25.
6 is provided. In the small cylinder hole 36, a reaction piston 52 that is integral with or in contact with the valve piston 38 is slidably fitted, and in the large cylinder hole 37, an elastic piston 50 that opposes the reaction piston 52, and this elastic piston 50
An output piston 51 superimposed on the front surface of the piston is slidably fitted. In order to prevent the output piston 51 from being pulled out of the large cylinder hole 37, the inner peripheral edge of the end wall plate 13a extends to the opening of the large cylinder hole 37.

An output rod 53 is provided protruding from the front surface of the output piston 51, and this output rod 53 is connected to the piston 55 of the brake master cylinder M.

Next, the operation of this embodiment will be explained. First, when the negative pressure booster B is at rest, as shown in Fig. 1,
The input rod 35 is located at the retraction limit, and the control valve 32 has the valve portion 41c seated on the first and second valve seats 40 ₁ and 40 ₂ so that both the front and rear working chambers 2b and 3b are connected to both the negative pressure chambers 2.
The control valve 32 is in a neutral state where it is disconnected from both the negative pressure chambers 2a and 3a and the atmospheric air inlet 33. Negative pressure is stored, and the negative pressure appropriately diluted with the atmosphere is maintained in both working chambers 2b and 3b. In this way, a slight forward force is applied to the front and rear booster pistons 4 and 6 due to the pressure difference generated between the negative pressure chamber 2a and the working chamber 2b at the front, and between the negative pressure chamber 3a and the working chamber 3b at the rear. ,
These forward forces are balanced with the elastic force of the return spring 23, so that both booster pistons 4 and 6 are stopped when they have advanced slightly from the retraction limit.

Now, when the brake pedal 34 is depressed to brake the vehicle and the input rod 35 and the valve piston 38 are moved forward, since both the booster pistons 4 and 6 are initially immovable, the second valve seat ₄₀₂ is moved to the valve portion 41c. Immediately move away from the air intake port 33 and connect both working chambers 2b, 3b to the atmosphere inlet 33.
communicate with. As a result, the air flowing into the valve body 41 from the air inlet 33 passes through the second valve seat 40 ₂ and then passes through the annular groove 38a to the second port 31,
31, the pressure is quickly introduced into the working chambers 2b, 3b, and the pressure in the chambers 2b, 3b is higher than that in the negative pressure chambers 2a, 3a. , 6 move forward in a responsive manner against the force of the return spring 23, and are connected to the piston 55 of the brake master cylinder M via the output rod 53.
drive forward. In this way, the brake master cylinder M can be operated without delay when the brake pedal 34 is depressed, and the vehicle can be braked.

In the above, when the atmosphere that has passed through the second valve seat ₄₀₂ flows to the second ports 31, 31 through the annular groove 38a of the valve piston 38, the atmosphere flows through the annular groove as shown by the arrow in FIG. 38a, the air is smoothly guided radially outward by the outer circumferential tapered surface of the air regulating member 61, so that the air can flow to the second ports 31, 31 without causing turbulence, thus reducing wind noise. Does not occur.

During such braking, the valve piston 38 also advances together with the input rod 35 and comes into contact with the elastic piston 50 via the reaction piston 52.
0 bulges and deforms toward the small cylinder hole 36 side in response to the actuation reaction force of both booster pistons 4 and 6, and a part of the reaction force acts on the reaction force piston 52, so that force is applied to the valve piston 38 and Feedback is provided to the brake pedal 34 via the input rod 35. Due to such a reaction force, the driver can sense the output of the output rod 53, that is, the magnitude of the braking force.

When the output of the output rod 53 exceeds the boosting limit point due to an increase in the pedal force on the brake pedal 34, that is, the input to the input rod 35, the front surface of the valve piston 38 comes into contact with the piston boss 10, so that the entire input is applied to the valve piston. 38, the output rod 53 via the piston boss 10, the elastic piston 50 and the output piston 51
As a result, the sum of the forward force due to the pressure difference between the booster pistons 4 and 6 and the forward force due to the input is output from the output rod 53.

Next, when the pedal force on the brake pedal 34 is released, the input rod 35 moves back together with the valve piston 38 due to the elastic force of the return spring 45, and the second valve seat 4
0 ₂ is seated on the valve portion 41c of the valve body 41, and the valve portion 41c is separated from the first valve portion 40 ₁ by a large distance. Communicating with the negative pressure chambers 2a, 3a, the pressure difference between the front and rear of each booster piston 4, 6 is immediately eliminated, and therefore both booster pistons 4, 6 retreat with the elastic force of the return spring 23.
The operation of the brake master cylinder M is released.

Also in this case, since the air in both working chambers 2b and 3b moves from the second port 31 to the first port 30,
When passing through the annular groove 38a of the valve piston 38,
Since the air is smoothly guided toward the first valve seat 40 ₁ by the air regulating member 61, no wind noise is generated.

When the input rod 35 returns to the retraction limit where the stopper plate 46 comes into contact with the partition wall 26a of the extension tube 26, the rear booster piston 6 temporarily pushes the protrusion 24 of the rear diaphragm 7 on the booster shell 1, as shown in FIG. Returning to the retraction limit where it contacts the rear wall, the first valve seat ₄₀₁ is seated on the valve seat 41c, and the valve portion 41c is slightly separated from the second valve seat ₄₀₂ , so that both working chambers 2b, 3b, and if both booster pistons 4 and 6 move forward a little due to the resulting pressure difference, the second valve seat 40
₂ and the valve portion 41c disappear, and the control valve 32 is brought to its original neutral state. In this way, the negative pressure diluted with the atmosphere is maintained in both working chambers 2b and 3b, and the negative pressure booster B enters the rest state as shown in FIG.

It goes without saying that the present invention is not limited to the tandem type negative pressure booster as in the above embodiment, but can also be applied to a single type negative pressure booster having one booster piston.

C. Effects of the invention As described above, according to the invention, a tapered air rectifying member whose outer diameter decreases toward the second valve seat is fitted in the annular groove in the middle part of the valve piston. When the passed atmosphere passes through the annular groove of the valve piston, it is directed to the second air by the air rectifying member in the annular groove.
It can be smoothly guided to the port side to prevent wind noise from occurring, and can greatly contribute to reducing the operating noise of the negative pressure booster.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a vertical sectional side view of a tandem negative pressure booster in a rest state, and FIGS. 2 and 3 are sectional views taken along lines - and - in FIG. 1. , FIG. 4 is a partial vertical side view showing a state immediately before the negative pressure booster returns to a resting state after completing its operation, and FIG. 5 is an explanatory view of the operation of the control valve in the negative pressure booster. B...Negative pressure booster, 1...Booster shell,
2a, 3a... negative pressure chamber, 2b, 3b... working chamber,
4, 6...Front booster piston, 10...Piston boss as a boss portion, 25...Valve cylinder, 30...
...First port, 31...Second port, 32...Control valve, 33...Atmospheric inlet, 35...Input rod, 3
8... Valve piston, 38a... Annular groove, 40 ₁ ...
...first valve seat, 40 ₂ ...second valve seat, 41 ...valve body,
60... caulking point, 61... air rectification member.

Claims (1)

[Scope of utility model registration request] A negative pressure chamber and an operating chamber are respectively formed on the front and rear sides of the booster piston housed in the booster shell, and the boss portion of the booster piston has a valve cylinder that is slidably supported on the rear wall of the booster shell. A first port that connects the inside of the valve cylinder to the negative pressure chamber and a second port that connects the inside of the valve cylinder to the working chamber are provided. 1st
A valve seat, a second valve seat formed at the rear end of the valve piston that is slidably fitted into the valve cylinder, and the first valve seat is biased toward the seating direction of the first and second valve seats. When seated on the second valve seat and separated from the second valve seat, the second port is communicated with the atmosphere, and when seated on the second valve seat and separated from the first valve seat, the second port is communicated with the valve body that communicates between the first and second ports. An annular groove is formed in the middle part of the valve piston, and the opening end of the second port faces the control valve, and by caulking the bottom wall of the annular groove, the valve piston is fitted into the central part of the groove. A negative pressure booster coupled to the front end of an input rod, characterized in that a tapered air rectifying member whose outer diameter decreases toward the second valve seat is fitted in an annular groove in the middle part of the valve piston. Negative pressure booster.