JPH042122Y2 - - 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, and a valve piston formed at the rear end of the valve piston that is slidably fitted into the valve seat and surrounded by the first valve seat. The second valve seat is biased toward the seating direction of the first and second valve seats, and when the first valve seat is seated and separated from the second valve seat, the second port is communicated with the atmosphere, and the second valve seat is When you sit on the seat and move away from the first valve seat, the first and second valve seats
A control valve consisting of a valve body that communicates between the ports is housed, and an annular groove is formed in the middle part of the valve piston, from which the open end of the second port faces, and by caulking the bottom wall of this annular groove, the valve piston The present invention relates to an improvement in a negative pressure booster in which a front end of an input rod is fitted into the center of the negative pressure booster.

(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 element seats on the first valve seat and the second valve seat is separated from the valve element, thereby opening the first port. At the same time, the second port and the atmosphere are communicated with each other, and the atmosphere that has passed between the second valve seat and the valve body sequentially passes through the annular groove of the valve piston and the second port to the rear side of the booster piston. The booster piston moves forward due to the pressure difference between the working chamber and the negative pressure chamber in front of the booster piston. In this case, when the air that has passed between the first valve seat and the valve body flows to the second port via the annular groove of the valve piston, the air flow is sharply bent by the annular groove.
Severe air turbulence may occur, resulting in wind noise.

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

B. Structure of the device (1) Means for solving the problem In order to achieve the above object, the present invention provides a second valve seat whose outer diameter decreases toward the valve body and whose generatrix is aligned with the axis of the valve piston. The valve piston is formed into a tapered shape that curves toward the second valve seat, and a tapered air rectifying member whose outer diameter decreases toward the second valve seat is fitted in the annular groove at the middle portion of the valve piston.

(2) Effect According to the above configuration, since the second valve seat is separated from the valve body, when the atmosphere passes between the valve body and the second valve seat, the tapered seat surface of the second valve seat prevents the atmosphere from entering the atmosphere. The flow is deflected radially and directed to a second port waiting on the side of the second valve seat. In particular, the tapered seat surface of the second valve seat has a generatrix curved toward the axis of the valve piston, thereby making it possible to smoothly bend the atmospheric flow toward the second port.

Furthermore, if the air advances beyond the second valve seat to the annular groove side of the valve piston, the flow is bent in the radial direction by the tapered surface of the air rectifying member and guided to the second port.

In this way, the air that has passed between the valve body and the second valve seat can flow into the second port without causing turbulence, so 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 interior 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.
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 from 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 6, 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, so that the gap between the contact surfaces of the end wall plate 13a and the piston boss 10 First and second ports 30 and 31 described below
communication between them is blocked.

Each through bolt 15 is arranged with its square head 15a facing the rear working chamber 3b side.
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 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) raised higher than the height of the nut 16 between them, and a return spring 23 is compressed between the 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 the rear diaphragm 7 coming into contact with the rear wall of the booster shell 1.

The front negative pressure chamber 2a is connected to a negative pressure source (not shown, for example, inside an intake manifold of an internal combustion engine) 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, as shown in FIG. 5, a valve piston 38 is provided at the front inside the valve cylinder 25
The spherical front end 35a of the input rod 35 passing through the air inlet 33 is fitted into the center of the valve piston 38. An annular groove 38a facing the opening ends of the second ports 31, 31 is formed on the outer periphery of the intermediate portion of the valve piston 38. By crimping, the spherical front end 35a of the input rod 35 is swingably connected to the valve piston 38.

Furthermore, in FIG. 5, an annular first valve seat 40 ₁ is provided protruding from the inner circumferential surface of the valve cylinder 25 , and an annular second valve seat 40 ₂ surrounded by this is formed on the rear end surface of the valve piston 38 . A valve body 41 that cooperates with these valve seats 40 ₁ and 40 ₂ is disposed within the valve cylinder 25 .

The seating surface of the second valve seat 40 ₂ is formed in a tapered shape with an outer diameter decreasing toward the valve body 41 , and in particular, the seating surface has a generatrix curved toward the axis of the valve piston 38 . The second valve seat ₄₀₂ has one side facing the opening end of the second port 31 into the valve cylinder 25 when separated from the valve body 41 (see FIG. 6).

The valve body 41 is made of rubber and has a cylindrical shape with both front and rear ends open.
a is a holding cylinder 42 fitted to the inner circumferential surface of the valve cylinder 25;
As a result, it is maintained in close contact with the inner circumferential surface of the valve 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.
The valve portion 41c is arranged to face 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 .

An air rectifying member 61 is fitted into the annular groove 38a of the valve piston 38, and its outer peripheral surface has an outer diameter that decreases toward the second valve seat ₄₀₂ and a generatrix curved toward the axis of the valve piston 38. It has a tapered shape. 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.

The rate of change in the outer diameter of the second valve seat 40 ₂ is set to be larger than the rate of change in the outer diameter of the air rectifying member 61,
This makes it possible to satisfy both the seating performance and the alignment performance of the valve portion 41c.

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 is extended 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, if the brake pedal 34 is depressed to control 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 40 ₂ moves into the valve portion 41c. Immediately move away from the air intake port 33 and connect both working chambers 2b and 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 between the second valve seat ₄₀₂ and the valve part 41c, then moves to the second port 31 and enters both the working chambers 2b and 3b. Since the pressure is quickly introduced into the chambers 2b and 3b than the negative pressure chambers 2a and 3a, a large forward force is obtained based on the pressure difference between them, and the booster pistons 4 and 6 resist the force of the return spring 23. The piston 55 of the brake master cylinder M is driven forward via the output rod 53. 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 passes between the second valve seat 40 ₂ and the valve part 41c, the flow of the atmosphere is bent in the radial direction by the tapered seat surface of the second valve seat 40 ₂ as shown by the arrow in FIG. and is guided to the second port 31 waiting on the side of the second valve seat ₄₀₂ . Especially the second
Since the tapered seat surface of the valve seat 40 ₂ has a generatrix curved toward the axis of the valve piston 38 , the flow of air can be smoothly bent toward the second port 31 .

Furthermore, even if the air passes over the second valve seat 40 ₂ and advances to the annular groove 38 a side of the valve piston 38 , the air flow is bent in the radial direction by the tapered surface of the air rectifying member 61 and flows smoothly into the second port 31 . be guided by.

In this way, the air that has passed between the second valve seat ₄₀₂ and the valve portion 41c can flow into the second port 31 without causing turbulence, so no wind noise is generated.

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 backward 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 part 41c of the valve body 41, and the valve part 41c is separated from the first valve part ₄₀₁ by a large distance, so that both the working chambers 2b and 3b are connected to each other through the first and second ports 30 and 31. Communicating with both 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 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 disappears, and the control valve 32 is brought to its initial 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 Effect of the invention As described above, according to the invention, the second valve seat is formed in a tapered shape in which the outer diameter decreases toward the valve body and the generatrix curves toward the axis of the valve piston. A tapered air rectifying member whose outer diameter decreases toward the second valve seat is fitted in the annular groove in the middle of the piston, so that when the second valve seat is separated from the valve body, air passes between them. The second valve seat and the air rectifying member smoothly guide the air flowing through the second port to prevent wind noise from occurring, thereby greatly 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 longitudinal 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 sectional side view showing the negative pressure booster immediately before it returns to the rest state after completing its operation, Fig. 5 is an enlarged view of the surrounding area of the control valve in Fig. 1, and Fig. 6 is a view of the control valve. It is an operation explanatory diagram. 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 a valve piston that is slidably fitted into a valve cylinder and surrounded by a first valve seat, and a seating direction of these first and second valve seats. When seated on the first 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 first and second ports are opened. A control valve consisting of a valve body that communicates with the valve piston is accommodated, and an annular groove is formed in the middle part of the valve piston, from which the open end of the second port faces, and by caulking the bottom wall of this annular groove, the valve piston and , in a negative pressure booster in which the front end of the input rod is connected to the center of the booster,
The second valve seat is formed into a tapered shape in which the outer diameter decreases toward the valve body and the generatrix curves toward the axis of the valve piston. A negative pressure booster characterized by being fitted with a tapered air rectifying member that decreases toward the valve seat.