JP2001063551A - Negative pressure booster - Google Patents

Abstract

PROBLEM TO BE SOLVED: To introduce a large quantity of atmospheric air into an operating chamber thereby to exercise high output at an early stage during emergent braking simply by adding a simple and inexpensive structure. SOLUTION: A valve piston 33 having an atmospheric air introducing valve seat 31 is engaged with an input piston 18, which connects an input rod 20 to a reaction mechanism 24, so as to be longitudinally slidable with a specified stroke (s) and is energized toward a retreat position R by means of set load of a return spring 44 that is smaller than that of a valve spring 36. A delay means 47 for delaying the retreat of the valve piston 33 from a forward position F that is caused by energizing force of the return spring 44 is provided between the valve piston 33 and the input piston 18. At the time of quick advancement of the input rod 20, the valve piston 33 advances with the input piston 18 while keeping the forward position F owing to the delay action of the delay means 47, thus opening the atmospheric air introducing valve seat 31 to the maximum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negative pressure booster used for boosting operation of a brake master cylinder of an automobile, and more particularly, to a booster shell having a front negative pressure chamber connected to a negative pressure source. A booster piston partitioned into a rear working chamber is accommodated, and a valve cylinder slidably supported on the rear wall of the booster shell is connected to the booster piston, and the valve cylinder can be moved back and forth in the valve cylinder. And a control valve for switching the working chamber to communicate with the negative pressure chamber and the atmosphere in accordance with the forward and backward movement of the input rod, and slides the valve cylinder, the input rod, and the booster shell. A reaction force mechanism for transmitting, to the output rod, a combined force between the input to the input rod, and the thrust of the booster piston due to the pressure difference between the working chamber and the negative pressure chamber, between the output rod movably supported. Intermediate and improvement.

[0002]

2. Description of the Related Art Conventionally, in such a negative pressure booster, as disclosed in, for example, Japanese Patent Application Laid-Open No. 9-2246, the amount of operation of a control valve is increased by exciting a solenoid device during emergency braking. 2. Description of the Related Art There has been known an apparatus in which a large amount of air is quickly introduced into a room so that an output rod exhibits a high output of a boosting limit.

[0003]

In the negative pressure booster disclosed in the above publication, not only an expensive solenoid device,
Since a sensor that detects the emergency braking condition is required,
There are disadvantages in that the configuration is complicated and the cost is high.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and by simply adding a simple and inexpensive structure, during an emergency brake, a large amount of air is quickly introduced into the working chamber to provide a high output to the output rod. It is an object of the present invention to provide the above-mentioned negative pressure booster capable of exhibiting the following.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a booster piston having a booster shell, the interior of which is divided into a front negative pressure chamber connected to a negative pressure source and a rear working chamber. And a valve cylinder slidably supported on the rear wall of the booster shell is connected to the booster piston, and an input rod movable forward and backward and a longitudinal movement of the input rod are provided in the valve cylinder. A control valve for switching the working chamber to communicate with the negative pressure chamber and the atmosphere in accordance with the control valve. The control valve is provided between the valve cylinder and the input rod and an output rod slidably supported by the booster shell. A negative pressure booster provided with a reaction force mechanism for transmitting to the output rod a resultant force of the input to the input rod and the thrust of the booster piston due to the pressure difference between the working chamber and the negative pressure chamber; And the input piston connecting the reaction force mechanism to the valve piston , Which is slidably fitted to the input piston between an axially retracted position and an advanced position along the axial direction, and which is formed at the rear end of the valve piston and at the valve cylinder. A negative pressure introduction valve seat surrounding the air introduction valve seat, and a common valve portion opposed to the atmosphere introduction valve seat and the negative pressure introduction valve seat so as to be seated on the front end thereof; The control valve is constituted by a cylindrical valve body mounted on a surface, and a valve spring for urging the valve portion in the seating direction of the air introduction valve seat and the negative pressure introduction valve seat. A first port communicating with the negative pressure chamber and opening between the negative pressure introduction valve seat and the valve body; and a second port communicating with the working chamber and opening between the atmosphere introduction valve seat and the negative pressure introduction valve seat. On the other hand, the inside of the valve body is communicated with the atmosphere, and the valve piston is smaller than the valve spring of the return spring. A delay means for urging the valve piston to the retreat position side with a load and delaying retraction of the valve piston from the forward position by the urging force of the return spring between the valve piston and the input piston. The feature of.

According to the first feature, at the time of emergency braking in which the input rod is rapidly advanced, the valve piston receives the delay effect of the delay means and advances with the input piston while maintaining the substantially advanced position. The air inlet valve seat of the valve is separated from the valve body of the valve body and opened to the maximum at the same time as the input rod advances, so that a large amount of air is introduced into the working chamber and the booster piston is connected between the negative pressure chamber and the working chamber. A large forward thrust due to a large pressure difference is immediately applied, so that the output of the output rod rises quickly and greatly, and it is possible to cope with emergency braking. In addition, since an expensive solenoid device and an emergency brake sensor are not required, the cost can be reduced.

On the other hand, during normal braking in which the input rod is advanced at a normal speed, the valve piston is not subjected to the delaying action of the delay means, and is returned to the retracted position by the biasing force of the return spring against the input piston that advances with the input rod. After moving,
Since the air introduction valve seat is appropriately separated from the valve portion of the valve body, the amount of air introduced into the working chamber can be restricted appropriately, and the output of the output rod can be moderately increased.

According to the present invention, in addition to the above features, the delay means is a seal member mounted on one of the sliding fitting surfaces of the valve piston and the input piston and closely contacting the other sliding fitting surface. The configuration is a second feature.

According to the second feature, the sealing member between the valve piston and the input piston also serves as the delay means, so that the structure can be further simplified and the cost can be reduced effectively.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

FIG. 1 is a longitudinal sectional view of a tandem type negative pressure booster according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view of a part of FIG. 1 (in a rest state), and FIG. 3 is a normal brake of the negative pressure booster. FIG. 4 is a diagram illustrating the operation of the negative pressure booster at the time of emergency braking, FIG. 5 is a diagram illustrating output characteristics of the negative pressure booster, and FIG. 6 is a modified example of a main part of the negative pressure booster. FIG. 3 is a sectional view corresponding to FIG.

1 and 2, a booster shell 1 of a negative pressure booster B has a pair of front and rear shell halves 1a and 1b connecting opposite ends to each other, and both shell halves 1a and 1a.
b, partition wall 1c partitioning the inside of the booster shell 1 into a front shell chamber 2 and a rear shell chamber 3, and the rear half half 1b is bolted to the front wall D of the vehicle compartment. The cylinder body Ma of the brake master cylinder M operated by the booster B is fixed to the front shell half 1a by bolts 9.

The front shell chamber 2 has a front booster piston 4 accommodated therein so as to be able to reciprocate back and forth, and is bonded to and overlapped with a rear surface thereof, and has a front shell half 1a and a partition plate 1c.
The front diaphragm 5 sandwiched therebetween partitions into a front front negative pressure chamber 2a on the front side and a rear front working chamber 2b on the rear side.
The front negative pressure chamber 2a is connected to a negative pressure source V (for example, the inside of an intake manifold of an internal combustion engine) via a negative pressure introducing pipe 14.

The rear shell chamber 3 is connected to a rear booster piston 6 housed in the rear shell chamber 3 so as to be able to reciprocate forward and backward, and is fixed between the two shell halves 1a and 1b together with the partition plate 1c. The rear diaphragm 7 defines a front rear negative pressure chamber 3a on the front side and a rear operating chamber 3b on the rear side.

The front and rear booster pistons 4 and 6 are each formed in an annular shape from a steel plate, and are integrally connected via a synthetic resin valve cylinder 10 fixed to the center. The valve cylinder 10 is slidably supported by a partition plate 1c via a seal member 11 and a rear extension cylinder 12 formed at the center of the rear shell half 1b via a seal member 13. The retreat limit of both booster pistons 4, 6 is defined by a large number of raised projections 7 a abutting the rear wall of the booster shell 1 on the rear surface of the rear diaphragm 7.

An input piston 18 slidably fitted to the inner peripheral surface of the valve cylinder 10, an input rod 20 connected to the input piston 18, and an operating chamber 2b in accordance with the forward and backward movement of the input rod 20. , 3b are connected to the negative pressure chambers 2a, 3a and the atmosphere. Input piston 18
Is constituted by a piston portion 18a slidably fitted to the inner peripheral surface of the valve cylinder 10 and a connecting tube portion 18b projecting rearward from the piston portion 18a.
The spherical front end portion 20a of the input rod 20 is fitted inside the b.
Is caulked. Thus, the input rod 20 is the input piston 1
8 is swingably connected. At the rear end of the input rod 20,
A brake pedal P for operating this forward is connected.

A cylindrical valve piston 33 is slidably fitted on the outer peripheral surface of the connecting cylindrical portion 18b of the input piston 18. The valve piston 33 has a forward position F (see FIG. 2) in contact with the piston portion 18a of the input piston 18, and a retracted position R (see FIG. 3) in contact with a stopper ring 45 locked on the connecting cylinder portion 18b. Between the valve piston 33 and the piston portion 18a of the input piston 18, a return spring 44 for urging the valve piston 33 toward the retreat position R is contracted. Is established. An O-ring 47 as a seal member that is in close contact with the other sliding fitting surface is mounted in the annular groove 46 formed on one sliding fitting surface of the valve piston 33 and the connecting cylinder portion 18b. Although the annular groove 46 is provided on the inner peripheral surface of the valve piston 33 in the illustrated example, it may be provided on the outer peripheral surface of the input piston 18. The O-ring 47 not only seals the sliding fitting portion of the valve piston 33 and the input piston 18 but also delays the retraction of the valve piston 33 from the forward position F by the urging force of the return spring 44 due to friction. Configure means.

As shown in FIG. 6, instead of the O-ring 47, the sealing member 4 having a rectangular cross section is provided in the annular groove 46.
7 'can also be attached.

The valve cylinder 10 has a first communication passage 28a communicating between the front and rear negative pressure chambers 2a and 3a, and the front and rear operation chambers 2b and 3a.
b and a first communication passage 28a communicating between the first communication passage 28b and the first communication passage 28a.
The first port 29a which opens to the inner peripheral surface of the valve cylinder 10
And the second communication passage 28b and the first port 29
a second port 29 that opens to the inner peripheral surface of the valve cylinder 10 in front of
b is formed. These first and second ports 29a,
An annular negative pressure introducing valve seat 30 is formed on the inner peripheral surface of the valve cylinder 10 at the middle part in the front-rear direction of 29b. The valve piston 33
At the rear end, an annular air introduction valve seat 31 is formed which is surrounded by a negative pressure introduction valve seat 30 with an annular passage 32 connected to the second port 29b interposed therebetween. One common valve body 34 facing the valve seat 31 is provided in the valve cylinder 10. The valve body 34 has an annular valve portion 34 that can be seated on the negative pressure introduction valve seat 30 and the atmosphere introduction valve seat 31.
a at the front end, an annular mounting bead portion 34b at the rear end, and a diaphragm portion 34c connecting the two portions 34a, 34b so as to be axially displaceable relative to each other. Is attached to the inner peripheral surface of the valve cylinder 10 by the front end of a cylindrical valve holder 35 fitted to the inner peripheral surface of the rear part of the valve cylinder 10. A valve spring 36 for urging the valve portion 34a in the seating direction between the valve seats 30 and 31 is contracted between the valve portion 34a and the input rod 20.
The set load of the return spring 44 is set smaller than that of the combustion spring 36.

In the above, the two valve seats 30, 31, the valve body 34 and the valve spring 36 constitute a control valve 38.

At the rear end of the rear extension cylinder 12, an inward flange 12a having an air inlet 39 opened at the center is integrally formed, and the input rod 20 is retracted by contacting the inner surface of the flange 12a. A stopper plate 40 defining a limit is fixed to the input rod 20 so as to be adjustable in the front-rear direction, and the input rod 20 is biased toward the retreat limit by an input return spring 41 supported by the valve holder 35.

An air filter 42 is mounted on the inner periphery of the rear end of the valve cylinder 10, through which the inside of the valve body 34 is always in communication with the air inlet 39. Air filter 4
2 has flexibility so as not to hinder the forward and backward movement of the input rod 20 with respect to the valve cylinder 10.

The front end of the valve cylinder 10 is formed in a large-diameter piston 15, and formed in the center of the large-diameter piston 15.
A large-diameter piston 1 is inserted into a cylinder hole 16
A small-diameter piston 17 reduced in diameter at a fixed ratio from 5 is slidably fitted. In the case of the illustrated example, the small-diameter piston 17 is connected to the front end of the valve piston 33 integrally. A cup 21 is slidably fitted around the outer periphery of the large-diameter piston 15, and the rear end face of the cup 21 is attached to the large-diameter piston 1.
5 is filled with a flat elastic piston 22.
The small-diameter piston 17 is usually provided with the elastic piston 22.
The rear end face is opposed to the predetermined gap g, and the predetermined gap g is set to be larger than the sliding stroke s of the valve piston 33 with respect to the input piston 18.

In the above, the large-diameter piston 15, the small-diameter piston 17, the elastic piston 22, and the cup body 21 constitute a reaction force mechanism for transmitting the resultant force of the input to the input rod 20 and the thrust of the booster pistons 4, 6 to the output rod 25. 24.

An output rod 25 projects from the front surface of the cup body 21. The output rod 25 is connected to the brake master cylinder M.
Of the piston Mb. In addition, a retainer 26 is provided in contact with the cup body 21 and the front end face of the valve cylinder 10, and a valve cylinder return spring 27 is contracted between the retainer 26 and the front wall of the booster shell 1.

Next, the operation of this embodiment will be described. [Pause of Negative Pressure Booster] In the rest state of the negative pressure booster B, as shown in FIGS. 1 and 2, the input rod 20 is at the retreat limit where the stopper plate 40 contacts the inward flange 12 a of the rear extension cylinder 12. And the booster pistons 4 and 6 are located at the retreat limit where the projection 7a of the rear diaphragm 7 abuts on the rear wall of the booster shell 1, and the control valve 38 controls the valve portion 34a of the valve body 34 to the atmosphere. The operation chambers 2b, 3b are seated on the introduction valve seat 31 and the negative pressure introduction valve seat 30, and are in a neutral state in which the two working chambers 2b, 3b are not communicated with any of the negative pressure chambers 2a, 3a and the air introduction port 39.

In this case, since the set load of the return spring 44 for urging the valve piston 33 in the backward direction is set smaller than the set load of the combustion spring 36 for urging the valve portion 34a forward, the input return spring 41 is set. Input rod 2 by the urging force of
0 is held at the retreat limit, the valve piston 33
The air-introducing valve seat 31 is brought into close contact with the valve portion 34a and the return spring 44 is compressed to occupy the forward position F on the input piston 18.

On the other hand, the valve piston 33 and the input piston 1
The O-ring 47 between the sliding fitting surfaces 8 prevents the negative pressure on the outer periphery of the valve piston 33 from leaking into the valve body 34 between the valve piston 33 and the input piston 18. [Normal brake] When the brake pedal P is depressed at a normal speed to brake the vehicle and the input rod 20, the input piston 18 and the valve piston 33 are advanced, the valve piston 33
At the normal forward speed, the valve piston 33 is almost unaffected by the delay action of the O-ring 47, and the biasing force of the return spring 44 moves toward the retreat position R on the input piston 18 as shown in FIG. And relatively slide. When the valve piston 33 reaches the retreat position R, the input rod 20, the input piston 18 and the valve piston 33 move forward as a unit, but initially, both booster pistons 4 and 6 are immovable. When the air introduction valve seat 31 of the valve piston 33 is appropriately separated from the valve portion 34a of the valve body 34, the second port 29b
Through the annular passage 32 to the atmosphere inlet 39 appropriately. As a result, the air flowing into the valve cylinder 10 from the air inlet 39 is appropriately restricted in the flow rate between the air inlet valve seat 31 and the valve portion 34a, and passes through the second port 29b to the two working chambers 2b and 3b. Since the chambers 2b and 3b are quickly introduced to make the chambers 2b and 3b higher in pressure than the negative pressure chambers 2a and 3a, the forward thrust based on the pressure difference between them is obtained, so that the two booster pistons 4 and 6 become the valve cylinder 10 and the large-diameter piston Valve return spring 2 with
7, the cup 21, that is, the output rod 25 is pushed forward through the large-diameter piston 15 and the elastic piston 22.

The elastic piston 2 of the reaction force mechanism 24
2 and the small-diameter piston 17 initially have a valve piston 33
Since there is a predetermined gap g larger than the sliding stroke s of the input rod 18 with respect to the input piston 18, the input rod 20 is not moved until the small-diameter piston 17 comes into contact with the elastic piston 22 after the air introduction valve seat 31 is separated from the valve portion 34 a. 5, the input rod 20 does not receive a reaction force from the reaction force mechanism 24 during the advance of the forward stroke, so that the output of the output rod 25 becomes a line a-a in FIG. As shown by b, the jumping is appropriately performed, whereby the piston Mb of the brake master cylinder M is appropriately rapidly operated, and the wheel brake can be quickly and smoothly operated.

Immediately thereafter, when the small-diameter piston 17 comes into contact with the elastic piston 22, the rear surface of the elastic piston 22 receives not only the thrust of the booster pistons 4 and 6 applied to the large-diameter piston 15 but also the input rod 20. Small diameter piston 17
And the elastic force of the elastic piston 2
Since the operating reaction force of the output rod 25 is acting on the front end face of the elastic rod 2, the elastic piston 22 is compressed and a part of the elastic piston 22 protrudes into the cylinder hole 16 to reduce the operating reaction force of the output rod 25. The part is transmitted to the input rod 20, so that the operator can sense the output of the output rod 25, that is, the magnitude of the braking force. As a result, the output of the output rod 25 increases in proportion to the input of the input rod 20, as indicated by the line bc in FIG.

In the meantime, the valve cylinder 10 integrated with the booster pistons 4 and 6 advances by the amount of advance of the input rod 20.
When the input rod 20 stops moving forward, the valve body 34 that has moved forward together with the valve cylinder 10 is seated again on the air introduction valve seat 31 and prevents further introduction of air into the working chambers 2b and 3b. The advance of the pistons 4 and 6 also stops, and a boost output corresponding to the input is obtained.

When the output of the output rod 25 exceeds the boosting limit,
The thrust due to the pressure difference between the booster pistons 4 and 6 is maximized, and the air introduction valve seat 31 remains separated from the valve body 34. Therefore, the output of the output rod 25 is reduced by the booster pistons 4 and 6.
5 and the thrust of the input rod 20 due to the depression force on the brake pedal P (the line cd in FIG. 5).
reference). [Brake release] When the pedaling force is released from the brake pedal P in order to release the braking state of the vehicle, first, the input rod 20 and the input piston 18 are retracted by the force of the input return spring 41. At this time, the air introduction valve seat 31 is connected to the valve portion 3 of the valve body 34.
When the valve piston 33 comes into close contact with the input piston 18, the valve piston 33 moves to the forward position F relative to the input piston 18 while compressing the return spring 44. Since the working chambers 2b and 3b are largely separated from the pressure introducing valve seat 30, the two working chambers 2b and 3b are connected via the second port 29b, the annular passage 32 and the first port 29a.
a, 3a. As a result, the introduction of air into both working chambers 2b and 3b is prevented, while the air in both working chambers 2b and 3b is sucked into the negative pressure limit V via both negative pressure chambers 2a and 3a.
Since those pressure differences disappear, the booster piston 4,
6 also retreats with the force of the valve cylinder return spring 27, and releases the operation of the master cylinder M.

When the input rod 20 retreats to the retreat limit where the stopper plate 40 contacts the inward flange 12a of the rear extension cylinder 12, the rear booster piston 6 moves the projection 7a of the rear diaphragm 7 to the rear wall of the booster shell 1. Returning to the retreat limit to make contact, the negative pressure introduction valve seat 30 is also brought into close contact with the valve portion 34a, and the control valve 38 is returned to the initial neutral state. [Emergency Braking] At the time of emergency braking in which the brake pedal P is rapidly depressed, as shown in FIG.
8 has a high forward speed, the valve piston 33 has an O-ring 4
Under the delay effect of the friction of 7, the robot advances with the input piston 18 while maintaining the substantially forward position F. Therefore,
The air introduction valve seat 31 of the valve piston 33 is separated from the valve portion 34a of the valve body 34 at the same time when the input rod 20 advances, and the air is immediately introduced into the working chambers 2b and 3b. Moreover, in this case, the free forward stroke of the input rod 20 from the time when the air introducing valve seat 31 is separated from the valve portion 34a to the time when the small-diameter piston 17 comes into contact with the elastic piston 22 is larger than in the case of the above-described normal braking. From this, while the input rod 20 advances this large forward stroke, the air introduction valve seat 31 is opened to the maximum, a large amount of air is introduced into the working chambers 2b and 3b, and the output of the output rod 25 is reduced. The jump is large as indicated by the line ab ′ of FIG. Thus, the output of the output rod 25 can be quickly and largely raised without using an expensive solenoid device and an emergency brake sensor, so that emergency braking can be handled.

When a certain period of time has passed since the air introduction valve seat 31 was opened to the maximum, the valve piston 33 is returned to the return spring 44.
5 returns to the retreat position R and enters the normal braking state, so that the output of the output rod 25 becomes the line b'-c- in FIG.
d.

The present invention is not limited to the above embodiment, and various design changes can be made without departing from the gist of the present invention. For example, the negative pressure booster B may be configured as a single type having a single booster piston.
The small-diameter piston 17 of the reaction force mechanism 24 is
3 and can be arranged in contact with the valve piston 33. When the negative pressure booster B is at rest, the valve portion 34a of the valve body 34 in the control valve 38 is connected to the negative pressure introduction valve seat 3.
It can also be made to leave from zero.

[0036]

As described above, according to the first aspect of the present invention, the input piston connecting the input rod and the reaction force mechanism is provided with the valve piston, which is located at the retracted position along the axial direction with respect to the input piston, and An air introduction valve seat formed at the rear end of the valve piston, which is slidably fitted between the advance positions, and a negative pressure introduction valve seat formed on the valve cylinder and surrounding the air introduction valve seat. A cylindrical valve body which is mounted on the inner peripheral surface of a valve cylinder having a common valve portion at the front end opposed to the air introduction valve seat and the negative pressure introduction valve seat so as to be seated, A control valve is constituted by a valve seat and a valve spring which urges in a seating direction with the negative pressure introducing valve seat, and a control valve communicates with the valve cylinder to the negative pressure chamber and opens between the negative pressure introducing valve seat and the valve body. One port and a second port communicating with the working chamber and opening between the air introduction valve seat and the negative pressure introduction valve seat are provided. The valve piston is urged to the retracted position with a set load of the return spring smaller than that of the valve spring, and the forward position between the valve piston and the input piston is caused by the urging force of the return spring of the valve piston. At the time of emergency braking, in which the input rod is rapidly advanced, the air introduction valve seat of the valve piston is largely separated from the valve portion of the valve body at the same time as the input rod is advanced, so that it is opened to the maximum during emergency braking. As a result, a large amount of air is introduced into the working chamber, a large forward thrust due to the pressure difference is immediately applied to the booster piston, and the output of the output rod rises quickly and greatly, and it is possible to respond to emergency braking. On the other hand, during normal braking in which the input rod moves forward at a normal speed, the air introduction valve seat is appropriately separated from the valve section of the valve body to appropriately restrict the amount of air introduced into the working chamber. , It is possible to moderately increase the output of the output rod, does not cause discomfort. In addition, since an expensive solenoid device and an emergency brake sensor are not required, the cost can be reduced.

According to a second feature of the present invention, the delay means is constituted by a seal member mounted on one of the sliding fitting surfaces of the valve piston and the input piston and closely contacting the other sliding fitting surface. As a result, the seal member between the valve piston and the input piston also serves as the delay means, so that the configuration can be further simplified and the cost can be effectively reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a tandem type negative pressure booster according to one embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a part of FIG. 1 (resting state).

FIG. 3 is a diagram illustrating the operation of the negative pressure booster during normal braking.

FIG. 4 is a diagram illustrating the operation of the negative pressure booster during emergency braking.

FIG. 5 is a diagram showing output characteristics of the negative pressure booster.

FIG. 6 shows a modification of a main part of the negative pressure booster, FIG.
Sectional drawing corresponding to FIG.

[Explanation of symbols]

 B: Negative pressure booster F: Forward position of valve piston R: Retracted position of valve piston V: Negative pressure source s: Sliding stroke of valve piston 1 ..Booster shell 2a: negative pressure chamber (front negative pressure chamber) 3a: negative pressure chamber (rear negative pressure chamber) 2b: working chamber (front working chamber) 3b: working chamber ( Rear working chamber 4 Booster piston (Front booster piston) 6 Booster piston (Rear booster piston) 10 Valve cylinder 18 Input piston 20 Input rod 24・ Reaction force mechanism 25 ・ ・ ・ Output rod 29a ・ ・ First port 29b ・ ・ Second port 30 ・ ・ ・ Negative pressure introduction valve seat 31 ・ ・ ・ Atmospheric introduction valve seat 33 ・ ・ ・ Valve piston 34 ・ ・ ・ Valve Body 34a Valve part 36 Valve spring 38 Control valve 44 Return spring 4 ... delay means (O-ring) 47 '... delay means (seal member)

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hiroki Kawakami 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (Reference) 3D048 BB21 BB37 CC27 EE00 EE15 EE16 EE17 EE20 EE29 QQ08

Claims (2)

[Claims] 1. A booster piston which partitions a booster shell (1) into a front negative pressure chamber (2a, 3a) connected to a negative pressure source (V) and a rear working chamber (2b, 3b). (4,6), and this booster piston (4,6)
A valve cylinder (10) slidably supported on the rear wall of the booster shell (1) is connected to the valve shell (1).
An input rod (20) that can be moved back and forth, and a control valve that switches the working chambers (2b, 3b) to communicate with the negative pressure chambers (2a, 3a) and the atmosphere according to the forward and backward movement of the input rod (20). (3
8) and the valve cylinder (10) and the input rod (20).
And the output rod (25) slidably supported by the booster shell (1), the input to the input rod (20), the working chambers (2b, 3b) and the negative pressure chamber (2a, 2b). 3a)
A reaction force mechanism (2) for transmitting a resultant force of the booster piston (4, 6) to the output rod (25) due to the pressure difference between the booster pistons (4, 6).
In the negative pressure booster provided with 4), the input rod (2
0) and the input piston (18) connecting the reaction force mechanism (24) to the valve piston (33), which is a retreat position (R) and an advance position (F) along the axial direction with respect to the input piston (18). An air introduction valve seat (31) formed at the rear end of the valve piston (33) so as to be slidable therebetween.
A negative pressure introducing valve seat (30) formed in the valve cylinder (10) and surrounding the air introducing valve seat (31); and an atmosphere introducing valve seat (31) and a negative pressure introducing valve seat (30). A cylindrical valve element (3) having a common valve portion (34a) at its front end, which is opposed to the seat (3), and attached to the inner peripheral surface of the valve cylinder (10).
4) and a valve spring (36) for urging the valve portion (34a) in the seating direction of the air introduction valve seat (31) and the negative pressure introduction valve seat (30) to constitute the control valve (38). A first port (29a) communicating with the negative pressure chambers (2a, 3a) and opening between the negative pressure introduction valve seat (30) and the valve body (34); The atmosphere introduction valve seat (31) and the negative pressure introduction valve seat (3) communicate with the working chambers (2b, 3b).
0), a second port (29b) that opens between the valve spring (44) and the inside of the valve body (34) is communicated with the atmosphere, and the valve piston (33) is connected to the valve spring (44) of a return spring (44). 36) The biasing force of the return spring (44) of the valve piston (33) is applied between the valve piston (33) and the input piston (18) while urging the valve piston (33) and the input piston (18) with a smaller set load. A delay means (47, 47 ') for delaying retreat from the forward position (F) due to the pressure drop. 2. The negative pressure booster according to claim 1,
The delay means is constituted by a seal member (47, 47 ') mounted on one of the sliding engagement surfaces of the valve piston (33) and the input piston (18) and in close contact with the other sliding engagement surface. A negative pressure booster characterized in that: