JPS624263B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention mainly relates to hydraulic brakes for automobiles,
A negative pressure booster that boosts a master cylinder such as a clutch using negative pressure, in particular a booster piston that accommodates the inside of a booster shell so that it can freely reciprocate back and forth, and a disc that overlaps the rear surface of the booster piston. A diaphragm having a circumferential bead connected to the central boss portion of the booster piston and an outer peripheral bead connected to the peripheral wall of the booster shell connects a first working chamber at the front portion connected to a negative pressure source and an input member. The booster shell is divided into the first working chamber and a second working chamber at the rear which is selectively communicated with the atmosphere through a control valve, and the booster shell has a disc portion of the booster piston and a rear second working chamber. The present invention relates to a type of device that is connected via a tie rod that passes through a diaphragm, and a sealing means is provided in a through hole of the disc portion that is penetrated by the tie rod.

This type of booster is used by fixing the rear end of the tie rod to the vehicle body, which serves as a support wall, and attaching a master cylinder to the front end of the tie rod. The applied forward thrust load can be transmitted to the support wall via the tie rod,
Therefore, since the burden of this load on the booster shell can be avoided, there is no need to provide the booster shell with high rigidity to withstand the above load, and it is possible to mold it from thin steel plate, synthetic resin, etc. to reduce its weight. It has the advantage of being able to achieve the following.

The present invention was proposed in order to further reduce the weight and productivity of the booster described above, by dividing the booster piston into a central boss part and a disc part, and making the disc part thin and relatively thin. The booster piston can be constructed from a rigid plate or the like with high rigidity, and the booster piston required by various boosters with different capacities can be easily obtained by simply replacing the disk portion with one having a different outer diameter. In addition, the rigidity of the through-hole part of the disc part that is penetrated by the tie rod is increased, and the relative position of the center boss part and the disc part in the circumferential direction can be determined by using the strengthened part. The purpose of the present invention is to provide a booster which can easily connect the circumferential bead together with the disc part to the central boss part while restraining the elongation of the circumferential bead. In the pressure type booster, the booster piston is divided into a central boss portion having a flange protruding from the outer periphery and a disk portion that abuts the rear surface of the flange, and a through hole in the disk portion that is penetrated by the tie rod. is defined by a short cylindrical portion integrally protruding from the front surface of the disk portion, and this short cylindrical portion is engaged with an arcuate positioning notch provided on the outer circumferential surface of the flange, thereby connecting the disk portion and the flange. A holding member that cooperates with the flange to hold the inner circumferential bead that is locked to the disk portion is fixed to the center boss portion.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In FIG. 1, W is a support wall that constitutes the rear wall of the engine room of an automobile, and a brake master cylinder M is connected to the front end of the support wall according to the present invention. A negative pressure booster S is installed.

The booster shell 1 of the booster S is composed of a front shell 1A and a rear shell 1B that are divided in the axial direction, and these are molded from a thin steel plate or synthetic resin. A booster piston 2 housed in this booster shell 1 so as to be able to reciprocate back and forth has a central boss portion 2a made of synthetic resin, and a disc portion 2b made of a steel plate that abuts the rear surface of a flange 3 integrally provided on the outer periphery of the boss portion 2a. The disc portion 2b is composed of an annular locking protrusion 47 formed by bending its inner circumferential end rearward, and an annular locking protrusion 47 formed by bending its outer circumferential end inward to avoid contact with a diaphragm 4, which will be described later. A curl portion 48;
It has an arcuate reinforcing rib 50 that protrudes from the front surface excluding a short cylindrical portion 49 (described later) and extends along the outer peripheral surface of the flange 3.

The rolling diaphragm 4 superimposed on the rear surface of the disc portion 2b has beads 4a, 4 on its outer periphery.
b, and has an annular locking groove 51 on the front surface of the inner peripheral bead 4a. in close contact,
Furthermore, the locking protrusion 47 is engaged with the locking groove 51 .
In this way, the inner peripheral bead 4a has two parts on the inner peripheral surface and the front surface.
Airtightness can be ensured on the surface, and the locking protrusion 4
7 restrains radial expansion. On the other hand, the outer peripheral bead 4b is clamped between the abutting ends of the front and rear shells 1A and 1B.

Further, an annular holding member 5 made of a spring steel plate is locked to the outer circumferential surface of the center boss portion 2a via a locking pawl 46 integrated therewith, and this holding member 5 is attached to the outer peripheral surface of the center boss portion 2a.
It cooperates with the flange 3 to sandwich the disc portion 2b and the inner peripheral bead 4a.

The booster piston 2 and diaphragm 4 divide the inside of the booster shell 1 into a first working chamber A at the front and a second working chamber B at the rear. The second working chamber B is always in communication with the intake manifold (not shown) of the engine which is the source of the engine, and the second working chamber B is connected to the first working chamber A or the atmosphere by a control valve (not shown) operated by the front and rear movements of the input rod 7. The communication can be switched alternately. Therefore, when the first working chamber A stores negative pressure, if the input rod 7 is advanced by operating the brake pedal 8 and the second working chamber B is communicated with the atmosphere, the gap between the two working chambers A and B is increased. A thrust force is applied to the booster piston 2 due to the pressure difference generated between the two, and the forward movement of the booster piston 2 can drive the operating piston 29 of the master cylinder M forward via the output rod 9.

Each end wall of the front and rear shells 1A and 1B, the disk portion 2b of the booster piston 2 and the diaphragm 4,
2 that extends parallel to the central axis of the
A book (or more) of tie rods 11 (see FIG. 5) pass through.

A tie rod 1 is installed on the inner surface of the end wall of the rear shell 1b.
A support tube 12 that passes through the tie rod 1 is welded, and a stepped flange 13 that integrally projects from the outer periphery of the tie rod 11 is fitted into this. At that time, the stepped flange 13,
A sealing member 16 for sealing the tie rod through hole 15 of the rear shell 1B is fitted into an annular housing 14 defined by the support tube 12 and the end wall of the rear shell 1B. A stop ring 17 that cooperates with this seal member 16 to clamp the large diameter portion of the stepped flange 13 is locked to the inner circumferential wall of the support tube 12. Thus, the tie rod 11 is fixed to the end wall of the rear shell 1B.

A clamping plate 18 is provided on the inner surface of the end wall of the front shell 1A.
are overlapped, thereby supporting the fixed end of the return spring 19 that springs the booster piston 2 in the backward direction. A pair of bosses 20 are provided at both ends of this clamping plate 18.
(Only one is shown in the figure) are integrally formed, and two tie rods 11 pass through these bosses 20 to prevent the clamping plate 18 from rotating. Further, a notch-shaped recessed hole 21 is provided on the inner end surface of the boss 20, and a corresponding notch-shaped flange 22 on the tie rod 11 is fitted into the hole to prevent the tie rod 11 from rotating. cod, boss 20
A seal housing 23 is recessed in the outer end surface of the front shell 1A, and a seal member 25 for sealing the tie rod through hole 4 of the front shell 1A is fitted into the housing 23.

The tie rod 11 is formed with bolts 11a and 11b at both ends projecting forward and backward of the booster shell 1, and a circlip 26 for preventing the front shell 1A from coming off is locked at the base of the front bolt 11a. This bolt 11a passes through a mounting flange 28 formed at the rear end of the cylinder body 27 of the master cylinder M, and a nut 30 is screwed onto its tip. At the same time, it cooperates with the clamping plate 18 to clamp and reinforce the end wall of the front shell 1A. Thus, front and rear shell 1
A and 1B are integrally connected via a tie rod 11.

Further, the rear bolt 11b passes through the support wall W and has a nut 31 screwed onto its tip, thereby fixing the booster shell 1 to the support wall W via the tie rod 11.

The through hole 32 of the disc part 2b penetrated by the tie rod 11 is defined by a stepped short cylindrical part 49 integrally protruding from the front surface of the disc part 2b. The area around the through hole 32 is reinforced. A synthetic resin protection ring 43 having approximately the same outer diameter as the large diameter portion 49b is fitted into the small diameter portion 49a of the short cylindrical portion 49.
This protective ring 43 has its front surface protruding forward from the tip of the small diameter portion 49a of the short cylindrical portion 49, and the through hole 3
This serves to prevent the rear end attachment portion 33b of the elastic boot 33 (described later) attached to the elastic boot 2 from being damaged from the tip edge of the small diameter portion 49a.

Disc portion 2b penetrated by two tie rods 11
The two through holes 32 are provided with the following sealing means.

That is, the tie rod 11 is surrounded by a bellows-shaped elastic boot 33 in the first working chamber A, the front end attachment part 33a of this boot 33 is attached to the outer periphery of the tie rod 11, and the rear end attachment part 33b is surrounded by the short cylindrical part 49 and the protection. Each ring 43 is tightly fitted. Therefore, the boot 33 can seal the through hole 32 without interfering with the back and forth movement of the booster piston 2 due to its elasticity.

The overlapping surfaces of the disc portion 2b of the booster piston 2 and the diaphragm 4 can be separated except for the inner peripheral bead 4a. It communicates with the second working chamber B via. The through hole 34 is defined by an annular bead 4c that is integral with the diaphragm 4, and this annular bead 4c is connected to the rear end 3 of the boot 33.
3b is closely attached to the rear surface so that it can be separated. In order to normally ensure this close contact, an elastic pressing piece 5a formed integrally extending from the outer periphery of the holding member 5 is brought into pressure contact with the rear surface of the annular bead 4c. This pressing piece 5a has a circular hole 35 or a U-shaped notch 35' as shown in FIG. 6 as an opening that allows communication between the through hole 34 and the second working chamber B.

In order to arrange the through hole 32 of the disk portion 2b, the through hole 34 of the diaphragm 4, and the openings 35, 35' of the pressing piece 5a concentrically with the tie rod 11, the front shell 1A and the rear shell of the booster shell 1 are arranged concentrically with the tie rod 11. 1
B, between the rear shell 1B and the diaphragm 4, between the diaphragm 4 and the disc part 2b of the booster piston 2, between the disc part 2b and the center boss part 2a, and between the center boss part 2b and the holding member 5, the corresponding circumferences The concave-convex engaging portion for determining the relative directional position is provided as follows.

That is, as shown in FIG. 3, the connecting ends of the front shell 1A and the rear shell 1B are provided with positioning notches 36 and positioning claws 37 that engage with each other, and as shown in FIG. And at the connecting part of the outer peripheral bead 4b of the diaphragm 4,
A positioning notch 38 and a positioning protrusion 39 that engage with each other are provided, and as shown in FIG.
will be provided. Further, as shown in FIG. 5, two arc-shaped positioning notches 42 are provided symmetrically on the outer periphery of the flange 3 of the central boss portion 2a with the central axis line in between, and these notches 42 are provided with two circular positioning notches 42 on the outer periphery of the flange 3 of the central boss portion 2a. The short cylindrical portions 49 and the protective ring 43 are engaged with each other. Further, as shown in FIG. 6, a positioning groove 44 that engages with each other is provided at the connecting portion of the central boss portion 2a and the holding member 5.
and positioning claws 45 are provided.

In the above configuration, when high negative pressure is stored in the first working chamber A, even if a large suction force due to the negative pressure acts on the particularly weak end wall of the front shell 1A, the suction force is Plate 18 and tie rod 11
is transmitted to and supported by the support wall W via the
The end wall of the front shell 1A is clamped and reinforced by the clamping plate 18 and the mounting flange 28 of the master cylinder M, so that no inward deformation occurs. Further, since the clamping plate 18 supports the fixed end of the return spring 19, the elastic force of the return spring 19 is also transmitted to the tie rod 11, so that the front shell 1A is not burdened with it.

When the booster piston 2 moves forward due to the forward operation of the input rod 7 by the brake pedal 8, the operating piston 29 of the master cylinder M is pushed forward to generate hydraulic pressure in a hydraulic chamber (not shown), thereby operating the wheel brakes. let At this time, the forward pressing force of the actuating piston 29 acts as a forward thrust load on the cylinder body 27 of the master cylinder M via the above-mentioned oil pressure, but this load is transmitted to the support wall W via the mounting flange 28 and tie rod 11. will be supported. Therefore, booster shell 1
The above load is not applied to the booster shell 1, and deformation of the booster shell 1 due to the load is prevented.

Next, when there is no negative pressure in the negative pressure source and therefore no negative pressure is stored in the first working chamber A, if the booster piston 2 is pushed forward by forward operation of the input rod 7, as shown in the figure. Since the second working chamber B is disconnected from the first working chamber A and communicated with the atmosphere by the control valve that does not operate, the air in the first working chamber A is compressed and supplied to the negative pressure source from the negative pressure introduction pipe 6. However, when the pressure in the chamber B increases to a certain value or more due to the discharge resistance, the pressure increases between the disk portion 2b of the booster piston 2 and the diaphragm 4, as shown in FIG. The annular bead 4c is separated from the rear end attachment portion 33b of the boot 33 against the elastic pressing force of the pressing piece 5a. As a result, the air in the first working chamber A is
A second gas under atmospheric pressure passes through the gap g and the through hole 34.
Because it is easily discharged to the working chamber B, the first working chamber A
There is almost no resistance to discharging the air inside, and the booster piston 2 can be manually operated easily.

As described above, according to the present invention, the booster piston includes a central boss portion having a flange protruding from the outer periphery;
Since the flange is divided into a disc part that comes into contact with the rear surface of the flange, the disc part can be made of a thin and relatively rigid steel plate, etc., thereby reducing the weight of the booster piston and making the booster even more efficient. Weight reduction can be promoted. In addition, by replacing the disk portion with one having a different outer diameter, booster pistons required by various boosters with different capacities can be easily obtained. Since it is shared by various boosters, even if many boosters with different capacities are required,
They have good productivity and can be provided at low prices.

In addition, the through hole of the disc part penetrated by the tie rod is defined by a short cylindrical part integrally protruding from the front surface of the disc part, and the short cylindrical part is provided on the outer peripheral surface of the flange for arc-shaped positioning. Since the short cylindrical portion is engaged with the notch, the through-hole portion of the disc portion can be effectively reinforced by the short cylindrical portion, and the center boss portion and the disc portion can be connected to each other by engaging the short cylindrical portion and the positioning notch. The relative position in the circumferential direction can be easily determined, and the short cylindrical portion serves both as a reinforcing member for the through-hole portion of the disc portion and as a positioning protrusion to be engaged with the positioning notch. The structure is simple and can contribute to cost reduction and improved assembly. In particular, it is advantageous to provide two or more short cylindrical portions and positioning notches symmetrically across the central axis of the booster piston, as this allows the concentric state of the central boss portion and the disc portion to be ensured at the same time.

Further, since a retaining plate that cooperates with the flange and clamps the disc part and the inner circumferential bead of the diaphragm engaged therewith is fixed to the central boss part, the central boss part and the disc part are held together by one holding member. The structure is simple, and even when a large pressure difference occurs between the first and second working chambers, the inner bead of the diaphragm can be reliably joined together in the circumferential direction of the inner bead. It is possible to restrain the elongation of the first working chamber, and to reliably prevent negative pressure from leaking from the first working chamber to the second working chamber.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of a negative pressure booster according to an embodiment of the present invention, Fig. 2 is an explanatory diagram of the operation of its main parts, and Figs. 3 and 4 are in the direction of the arrow in Fig. 1. Figures 5 and 6 are the - and - lines in Figure 1.
FIG. A, B...First and second working chambers, S...Boosting device, 1...Booster shell, 2...Booster piston, 2a...Center boss portion, 2b...Disc portion, 3
... Flange, 4 ... Diaphragm, 4a ... Inner circumference bead, 4b ... Outer circumference bead, 5 ... Holding member, 6 ... Negative pressure introduction pipe, 7 ... Input rod, 11 ...
Tie rod, 32...Through hole in disc portion, 33...Elastic boot as sealing means, 42...Positioning notch, 47...Locking protrusion, 49...Short tube portion, 5
0... Rib, 51... Locking groove.

Claims (1)

[Scope of Claims] 1 The inside of the booster shell includes a booster piston housed therein so as to be able to reciprocate back and forth, and an inner circumferential bead that overlaps the rear surface of the disk portion of the booster piston and connects the inner peripheral bead to the central boss portion of the booster piston. At the same time, the outer peripheral bead is connected to a negative pressure source by a diaphragm connected to the peripheral wall of the booster shell, and is connected to the first working chamber or the atmosphere through a control valve linked to an input member. The booster shell is divided into a rear second working chamber which is selectively communicated with each other, and the front and rear end walls of the booster shell are connected via a tie rod that passes through the disk portion and the diaphragm of the booster piston. In the negative pressure booster, the booster piston has a central boss portion having a flange protruding from its outer periphery;
The flange is divided into a disc part that abuts the rear surface of the flange, and a through hole in the disc part that is penetrated by the tie rod is defined by a short cylindrical part integrally protruding from the front surface of the disc part. The short cylindrical portion is engaged with an arcuate positioning notch provided on the outer circumferential surface of the flange, and cooperates with the flange to clamp the disk portion and the inner peripheral bead that is locked to the disk portion. A negative pressure booster, characterized in that a holding member is fixed to the central boss portion. 2. In what is stated in claim 1,
In the negative pressure booster, two or more short cylinder portions and two or more positioning notches are provided symmetrically across the center axis of the booster piston. 3 In what is stated in claim 1,
The disc part is a negative pressure booster, in which a circular rib extending along the outer circumferential surface of the flange is raised on the front surface excluding the short cylinder part.