JPH06219264A - Valve element holding structure in negative pressure booster - Google Patents

Abstract

PURPOSE:To prevent damage of a valve element mounted on a valve element holding tube and to fix the valve element holding tube without using an exclusive use retaining part of snap ring or the like, in the case of fitting a valve element holding surface to a valve tube connected to a booster piston, in a negative pressure booster. CONSTITUTION:An internal peripheral surface of a synthetic resin-made valve tube 8 is formed in a tapered surface of spreading a diameter from a closely attaching part to a bead-shaped base end part 20a of a valve element 20 toward an opening end of the valve tube 8, a tapered surface fitted to this tapered surface is formed in the periphery of a valve element holding tube 21, a circular arc-shaped stop groove 39 is formed in the internal peripheral surface of the valve tube 8, and a stop pawl 41 elastically engaged with this stop groove 39 is integrally formed with the valve element holding tube 21.

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 for boosting a master cylinder in an automobile, a motorcycle, etc., and more particularly to a synthetic resin valve cylinder having a front end connected to a booster piston and a rear end opened. The valve body holding cylinder is fitted and fixed to the inner peripheral surface of the valve body 8, and the base end portion of the valve body disposed in the valve cylinder is disposed on the outer peripheral surface of the front end portion of the valve body holding cylinder. The present invention relates to an improvement, which is provided with an annular holding groove that is mounted in close contact with.

[0002]

2. Description of the Related Art In a conventional negative pressure booster, for example, as disclosed in Japanese Utility Model Laid-Open No. 1-73459, it is formed on the inner peripheral surface of a valve cylinder for fixing the valve body holding cylinder to the valve cylinder. The front end of the valve body holding cylinder is brought into contact with the annular stepped portion, and the circlip for pressing the rear end thereof is engaged with the annular locking groove formed on the inner peripheral surface of the valve cylinder.

[0003]

In such a conventional structure, when the valve body holding cylinder is fitted into the valve cylinder with the base end portion of the valve body being held in the holding groove during assembly, the valve body is Since there is a risk that the proximal end of the valve will be damaged by the annular step on the inner peripheral surface of the valve cylinder, careful assembly is required. Since the annular locking groove on the inner peripheral surface of the valve cylinder is difficult to form with a mold, it is obtained by cutting, and a dedicated circlip is required to press the rear end of the valve body holding cylinder. This means that the production cost will be quite high.

The present invention has been made in view of the above circumstances, and does not require the formation of an annular step portion on the inner peripheral surface of the valve cylinder, which may damage the valve body, and also provides a dedicated circlip or the like. An object of the present invention is to provide a valve body holding structure having a simple structure that can fix the valve body holding cylinder to the valve cylinder very easily without using a pressing part.

[0005]

In order to achieve the above object, the present invention is directed to an inner peripheral surface of a valve cylinder from a predetermined contact portion with a base end portion of a valve body toward an open end of the valve cylinder. On the other hand, the outer peripheral surface of the valve body holding cylinder is formed into a tapered surface that fits into the tapered surface while the inner peripheral surface of the valve cylinder is formed into a plurality of arcuate shapes extending in the circumferential direction. While the locking groove is provided, a locking claw that elastically engages with the locking groove is integrally provided on the outer peripheral surface of the valve body holding cylinder.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a vertical sectional view of the negative pressure booster B.
In the figure, on the front surface of the booster shell 1 of the negative pressure booster B, a brake master cylinder M operated by the booster is attached.

The booster shell 1 consists of a front shell half 2 and a rear shell half 3 which join the open ends together. The booster shell 1 is divided into a negative pressure chamber 6 on the front side and a working chamber 7 on the rear side by a booster piston 4 made of a steel plate accommodated in the booster shell 1 so as to be capable of reciprocating back and forth and a diaphragm 5 superposed on the rear surface thereof. To be done. The outer peripheral bead of the diaphragm 5 is sandwiched between the connecting portions of the two shell halves 2 and 3, and the inner peripheral bead is fitted to the outer periphery of the cylindrical valve cylinder 8 together with the central boss 4a of the booster piston 4 and is engaged. It is fixed with a snap ring 9. The valve cylinder 8 extends rearward through the center boss 4a of the booster piston 4 and extends to the rear shell half 3
It is slidably supported via a plain bearing 10 and a seal member 11 on a rear extension cylinder 3a that is continuously provided on the rear wall.

The negative pressure chamber 6 is constantly connected to an intake manifold (not shown) of the internal combustion engine, which is a negative pressure source, via a negative pressure introduction pipe 12, and the working chamber 7 is a control valve 13 provided in a valve cylinder 8. The negative pressure chamber 6 or the air inlet 1 at the end of the rear extension cylinder 3a
4 is alternately switched to communication.

The booster piston 4 is constantly urged by a return spring 15 that is compressed in the negative pressure chamber 6 in the retracting direction, that is, toward the working chamber 7, and the retracting limit of the booster piston 4 is a large number of annular arrays raised on the back surface of the diaphragm 5. The protrusion 5a is regulated by coming into contact with the inner surface of the rear wall of the booster shell 1.

In the valve cylinder 8, an input rod 17 connected to a brake pedal 16 and the control valve 13 operated by the input rod 17 are provided.
Are provided as follows. That is, the valve piston 18 is slidably fitted in the front portion of the valve cylinder 8 and the valve piston 1
A front end of an input rod 17 penetrating through the atmosphere introducing port 14 is coupled to 8 so as to be swingable. An annular first valve seat 19 ₁ is formed on the inner surface of the valve cylinder 8, and an annular second valve seat 19 ₂ surrounded by this is formed on the rear end surface of the valve piston 18, and these valve seats 19 ₁ , A valve body 20 cooperating with 19 ₂ is arranged in the valve cylinder 8 (see also FIG. 2). The valve body 20 is made of rubber and has a tubular shape with its front and rear ends open, and its rear end portion, that is, a bead-shaped base end portion 20a, is
It is mounted in an annular holding groove 21a formed on the outer periphery of the front end portion of the valve body holding cylinder 21 fitted inside and is held in close contact with the inner peripheral surface of the valve cylinder 8. The mounting structure of the valve body holding cylinder 21 will be described later.

The valve body 20 includes a thin flexible portion 20b bent inward in the radial direction from the base end portion 20a, and a thick valve portion 20c connected to the front end of the flexible portion 20b.
The valve portion 20c has the first and second valve seats 19 ₁ and 19 ₂
Is placed opposite to. The valve portion 20c can be moved back and forth due to the deformation of the flexible portion 20b, is seated on the first and second valve seats 19 ₁ and 19 ₂ when moving forward, and is received by the front end of the valve body holding cylinder 21 when moving backward. .

An annular reinforcing plate 22 is embedded in the valve portion 20c, and a valve spring 23 for urging the valve portion 20c toward both valve seats 19 ₁ and 19 ₂ is embedded between the annular reinforcing plate 22 and the input rod 17. Reduced.

Further, on the inner surface of the valve cylinder 8, a first port 24 ₁ connected to the negative pressure chamber 6 is outside the first valve seat 19 ₁ and a second port 24 ₂ connected to the working chamber 7 is provided on the valve seat 19 1. Open each inside ₁ . The inside of the second valve seat 19 ₂ is the valve body 2
0 and the air inlet port 14 through the hollow portion of the valve body holding cylinder 21.
Communicate with.

Thus, the valve body 20, the valve spring 23 and the first and second
The control valve 13 is configured by the second valve seats 19 ₁ and 19 ₂ .

Between the input rod 17 and the valve body holding cylinder 21, a return spring 25 for urging the input rod 17 toward its retracted limit is contracted. The retracting limit of the input rod 17 is regulated by the stopper plate 26 screwed to the input rod 17 so as to be adjustable in advance and retreat, and brought into contact with the inner surface of the end wall 3b of the rear extension cylinder 3a. Therefore, when the stopper plate 26 is rotated, the screwing position between the stopper plate 26 and the input rod 17 is changed, so that the retreat limit of the input rod 17 can be adjusted back and forth. After the adjustment, the stopper plate 26 is fixed by tightening a lock nut 27 that is also screwed to the input rod 17. The stopper plate 26
A ventilation hole 28 is formed in the air inlet 28 so that the air inlet 14 is not blocked.

An air filter 29 for filtering the air taken into the valve cylinder 8 from the atmosphere introduction port 14 is attached to the valve cylinder 8 around the input rod 17. This air filter 29
Has an appropriate flexibility so as not to hinder the relative displacement of the input rod 17 and the valve cylinder 8.

Further, the valve cylinder 8 has a large cylinder hole 30 with a bottom opening on the front surface thereof, a cylindrical convex portion 31 protruding from the bottom surface of the large cylinder hole 30, and a small cylinder penetrating the convex portion 31. A hole 32 is provided. Large cylinder hole 30
A cup-shaped output piston 33 is slidably fitted in this, and the convex portion 31 is slidably fitted in the output piston 33 by filling an elastic material 34 such as rubber.
The small cylinder hole 32 is slidably fitted with a reaction force piston 35 projecting from the front end surface of the valve piston 18.

An output rod 36 is projectingly provided on the front surface of the output piston 33, and the output rod 36 is connected to the piston 37 of the master cylinder M.

Now, the mounting structure of the valve body holding cylinder 21 to the valve cylinder 8 will be described with reference to FIGS. 2 is shown in FIG.
2 is an enlarged view of the valve cylinder and the valve body holding cylinder in FIG.
3 is a developed view of the inner peripheral surface of the valve cylinder 8, and FIG. 5 is a developed view of the outer peripheral surface of the valve body holding cylinder 21.

Both the valve cylinder 8 and the valve body holding cylinder 21 are formed by using a thermoplastic or thermosetting synthetic resin as a material. At that time, as shown in FIGS. 2 to 4, a pair of guide grooves 38 and a pair of locking grooves 39 are provided on the inner peripheral surface of the valve cylinder 8.
Are formed so as to be alternately arranged in the circumferential direction. Guide groove 38
Starts from the rear end surface of the valve cylinder 8 and ends at a position of a predetermined depth of the valve cylinder 8, and its cross section is arcuate. on the other hand,
The locking groove 39 has a groove width much shorter than the axial length of the guide groove 38, has an arc shape extending in the circumferential direction of the valve cylinder 8, and is arranged at an axially intermediate position of the guide groove 38. . That is, the locking groove 39 is offset from the terminal end 38a of the guide groove 38 to the rear end side of the valve cylinder 8 by a predetermined distance L.

As shown in FIGS. 2, 3 and 5, a pair of guide claws 40 and locking claws 41 projecting from the outer peripheral surface of the valve body holding cylinder 21 are provided at the rear end of the valve body holding cylinder 21. 21 are integrally formed so as to be alternately arranged in the circumferential direction. The guide claw 40 is slidably fitted in the guide groove 38 so that the end 3 of the groove 38
8a, the locking claw 41
Is adapted to elastically engage with the locking groove 38 when the guide claw 40 comes into contact with the terminal end 38a of the guide groove 38. Therefore, an offset of the same distance L as that between the guide groove 38 and the locking groove 39 is provided between the guide claw 40 and the locking claw 41.

Further, the valve body holding cylinder 21 is provided with a notch 42 for providing elasticity to the base of the locking claw 41 between the guide claw 40 and the locking claw 41.

Referring again to FIG. 2, as indicated by an angle θ, the outer peripheral surface of the valve cylinder 8 and the inner peripheral surface of the valve body holding cylinder 21 which are fitted to each other are respectively formed with the base end portion 20a of the valve body 20. The tapered surface is formed so that its diameter increases from the predetermined contact portion toward the rear (rightward in the figure) open end.

Next, the operation of this embodiment will be described.
First, in the rest state of the negative pressure booster B, as shown in FIG. 1, the input rod 17 is located at the backward limit, and in the control valve 13, the valve portion 20c of the valve body 20 is moved to the first and second valve seats 19 ₁ , 19 ₂
The working chamber 7 is in a neutral state in which the negative pressure chamber 6 and the atmosphere introduction port 14 are in communication with each other, and such a control valve 13 allows the negative pressure chamber 6 to pass through the negative pressure introduction pipe 12. The supplied negative pressure of the negative pressure source is stored, and the working chamber 7 holds the negative pressure appropriately diluted with the atmosphere. Therefore, a slight forward force is applied to the booster piston 4 due to the pressure difference between the negative pressure chamber 6 and the working chamber 7, but the forward force and the elastic force of the return spring 15 balance each other, so that the booster piston 4 moves. It stopped at a position slightly advanced from the backward limit.

Now, the brake pedal 1 is used to brake the vehicle.
6 is depressed and the input rod 17 and the valve piston 18 are moved forward, the booster piston 4 is initially immobile, so the second valve seat 19 ₂ is immediately separated from the valve portion 20c and the working chamber 7 is opened to the atmosphere introduction port 14 Communicate with. As a result, the atmospheric air flows into the working chamber 7 from the atmospheric air inlet 14 through the second valve seat 19 ₂ and the second port 24 ₂ to bring the chamber 7 to the atmospheric pressure, so that the negative pressure chamber 6 and the working chamber 7 The booster piston 4 moves forward against the force of the return spring 15 by the forward force based on the pressure difference generated between them, and drives the piston 37 of the master cylinder M forward through the output rod 36 to control the vehicle. Can be powered.

During such braking, the valve piston 18 moves forward together with the input rod 17, and the elastic member 3 passes through the reaction force piston 35.
4, the elastic member 34 receives the operation reaction force of the output rod 36 via the output piston 33, and the elastic member 34 receives the operating force of the output rod 36.
Since it bulges and deforms to the 2 side and causes a part of the reaction force to act on the reaction force piston 35, the force is fed back to the brake pedal 16 side via the valve piston 18 and the input rod 17, and the operator outputs the output rod. The output of 36, that is, the magnitude of the braking force can be sensed.

Next, when the pedaling force to the brake pedal 16 is released, first, the input rod 17 is retracted together with the valve piston 18 by the elastic force of the return spring 25, and the second valve seat 19 ₂ is moved to the valve portion 2.
Since the valve portion 20c is largely separated from the first valve seat 19 ₁ while being seated at 0c, the working chamber 7 communicates with the negative pressure chamber 6 through the first and second ports 24 ₁ and 24 ₂ , and both chambers 6 and 6. 7
The pressure difference between them disappears. Therefore, booster piston 4
Moves backward by the elastic force of the return spring 15 and releases the operation of the master cylinder M. Then, when the input rod 17 returns to the retracted limit where the stopper plate 26 contacts the end wall 3c of the extension cylinder 3a, the booster piston 4 once retracts the protrusion 5a of the diaphragm 5 to contact the rear wall of the booster shell 1. Returning to the limit, the first valve seat 19 ₁ is seated on the valve portion 20c and the valve cylinder 8 is slightly separated from the second valve seat, so that the atmosphere is introduced again into the working chamber 7 through the second port 24 _2. . However, when the booster piston 4 slightly advances due to the pressure difference caused by the introduction of the atmosphere,
The small gap between the second valve seat 19 ₂ and the valve portion 20c disappears,
The control valve 13 is brought to the initial neutral state. Thus working chamber 7
Negative pressure diluted in the atmosphere is held in the negative pressure booster B
Becomes the rest state of FIG.

In such a negative pressure booster B, in order to mount the valve body holding cylinder 21 on the valve cylinder 8, first, the base end portion 20a of the valve body 20 is mounted in the holding groove 21a of the valve body holding cylinder 21.
A valve body holding cylinder 21 is inserted into the valve cylinder 8 from the rear with the valve body 20 at the top. At this time, in the valve body holding cylinder 21, the guide claw 40 enters the valve cylinder 8 ahead of the locking claw 41, so that the guide claw 40 first fits into the guide groove 38 of the valve cylinder 8. . Then, when the valve body holding cylinder 21 is further fitted into the valve cylinder 8 under the fitting of the guide claw 40 and the guide groove 38, the locking claw 41 once bends inward on the inner peripheral surface of the valve cylinder 8. However, when the guide claw 40 hits the end 38a of the guide groove 38, the locking claw 41 automatically engages with the locking groove 39 by its restoring force.

Thus, the locking claw 41 and the locking groove 39
It is possible to prevent the valve body holding cylinder 21 from disengaging from the valve cylinder 8 by the engagement. The fitting of the guide claw 40 and the guide groove 38 guides the engagement of the locking claw 41 and the locking groove 39,
This helps prevent the locking claws 41 from overshooting the locking groove 39.

Further, since the inner peripheral surface of the valve cylinder 8 and the outer peripheral surface of the valve body holding cylinder 21 which are fitted to each other are formed into the tapered surfaces as described above, the valve body holding cylinder 21 is randomly formed on the valve cylinder 8. Even when fitted, the base end portion 20a of the valve body 20 is guided to the tapered surface of the inner circumference of the valve cylinder 8 and accurately set at a predetermined contact portion with the inner circumference surface of the valve cylinder 8 without being damaged. Therefore, the sealed state between the inner peripheral surface of the valve cylinder 8 and the valve body 20 can be secured. Moreover, since the valve body 20 and the valve body holding cylinder 21 do not rub strongly against the taper surface of the inner circumference of the valve cylinder 8 until the predetermined fixed position on the valve cylinder 8 is reached, the fitting can be easily performed. You can

Further, since the engaging groove 39 on the inner peripheral surface of the valve cylinder 8 is not circular but arcuate, it can be easily formed at the same time as the molding of the valve cylinder 8 and engages with the engaging groove 39. Since the locking claw 41 is formed integrally with the valve body holding cylinder 21, the manufacturing cost can be reduced.

In the above embodiment, various design changes can be made without departing from the gist of the present invention. For example, when the locking claw 41 and the locking groove 39 are positioned using an assembly jig, the guide claw 40 and the guide groove 38 can be omitted.

[0034]

As described above, according to the present invention, the inner peripheral surface of the valve cylinder is formed into a taper surface that expands from the predetermined contact portion with the base end of the valve body toward the open end of the valve cylinder. On the other hand, the outer peripheral surface of the valve body holding cylinder is formed into a tapered surface that fits the tapered surface, and the inner peripheral surface of the valve cylinder is provided with a plurality of arcuate locking grooves extending in the circumferential direction. Since the locking claw that elastically engages with this locking groove is integrally provided on the outer peripheral surface of the valve body holding cylinder, even if the valve body holding cylinder is randomly inserted into the valve cylinder, the valve body remains inside the valve cylinder. Guided by the tapered surface of the circumference, set accurately at a predetermined contact point with the inner peripheral surface of the valve cylinder, and not damaged, and the valve body and valve body holding cylinder must be held until the predetermined fixed position is reached. Assembleability is remarkably improved because the taper surface of the inner circumference of the valve cylinder is not strongly rubbed and the fitting can be performed easily. Further, since the locking groove on the inner peripheral surface of the valve cylinder is not circular but arcuate, it can be formed simultaneously with the molding of the valve cylinder.
The locking claw that engages with the locking groove is formed integrally with the valve body holding cylinder, and a dedicated pressing component is not required, which contributes to a reduction in manufacturing cost.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of a negative pressure booster showing an embodiment of the present invention.

FIG. 2 is an enlarged view of a valve cylinder and a valve body holding cylinder portion in FIG.

FIG. 3 is a view on arrow 3 of FIG.

FIG. 4 is a development view of the inner peripheral surface of the valve cylinder.

FIG. 5 is a development view of the outer peripheral surface of the valve body holding cylinder.

[Explanation of symbols]

 B Negative pressure booster 4 Booster piston 8 Valve cylinder 20 Valve body 21 Valve body holding cylinder 21a Holding groove 39 Locking groove 41 Locking claw

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[Procedure amendment]

[Submission date] June 7, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

As shown in FIGS. 2, 3 and 5, a pair of guide claws 40 and locking claws 41 projecting from the outer peripheral surface of the valve body holding cylinder 21 are provided at the rear end of the valve body holding cylinder 21. 21 are integrally formed so as to be alternately arranged in the circumferential direction. The guide claw 40 is slidably fitted in the guide groove 38 so that the end 3 of the groove 38
8a, the locking claw 41
Is adapted to elastically engage with the locking groove 39 when the guide claw 40 comes into contact with the terminal end 38a of the guide groove 38. Therefore, an offset of the same distance L as that between the guide groove 38 and the locking groove 39 is provided between the guide claw 40 and the locking claw 41.

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 4

[Correction method] Change

[Correction content]

[Figure 4]

Claims (1)

[Claims] 1. A valve holding cylinder (21) is fitted and fixed to the inner peripheral surface of a synthetic resin valve cylinder (8) having a front end connected to a booster piston (4) and a rear end opened. Holding tube (21)
On the outer peripheral surface of the front end portion of the valve body (20), the base end portion (20a) of the valve body (20) arranged in the valve cylinder (8) is attached in an adhered state with the inner peripheral surface of the valve cylinder (8). A holding groove (21a) is provided,
In the valve body holding structure of the negative pressure booster, the inner peripheral surface of the valve cylinder (8) is connected to the base end portion (20) of the valve body (20).
The valve body holding cylinder (21) is formed on the valve body holding cylinder (21) while forming a tapered surface that expands from a predetermined contact portion with a) toward the open end of the valve cylinder (8).
The outer peripheral surface of the valve cylinder (8) is formed into a tapered surface that fits into the tapered surface, and the inner peripheral surface of the valve cylinder (8) is provided with a plurality of arcuate locking grooves (39) extending in the circumferential direction. A locking claw (41) elastically engaged with the locking groove (39) is integrally provided on the outer peripheral surface of the valve body holding cylinder (21).
Valve holding structure for negative pressure booster.