JPS628341B2 - - 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 circumferential bead is connected to the central boss portion of the booster piston, an outer peripheral bead is connected to the peripheral wall of the booster shell, and a first working chamber at the front portion is connected to a negative pressure source by a diaphragm, and is interlocked with 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 a disk portion of the booster piston is separated between the front and rear end walls of the booster shell. An elastic boot that surrounds the tie rod is connected through a tie rod that passes through the tie rod, and one end of the elastic boot is fitted into the tie rod, and the other end is fitted into a through hole in the disc portion that is penetrated by the tie rod. relating to things.

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 reduce its weight by molding it with thin steel plate or synthetic resin. It has the advantage of being able to achieve the following.

When the disc part of the booster piston is made of a thin plate in order to further reduce the weight of the booster, the present invention aims to increase the rigidity of the through-hole part of the disc part penetrated by the tie rod, and to increase the rigidity of the booster piston. It is an object of the present invention to provide the above-mentioned boosting device, which allows the other end of the telescopic boot to be easily and securely attached to the disc part by using the reinforced part while ensuring airtightness of the other end. It is.

Hereinafter, one embodiment of the present invention will be explained with reference to the drawings. In Fig. 1, W is a support wall that constitutes the rear end wall of the engine room of an automobile, and a brake master cylinder M is connected to the front end of the support wall. The negative pressure booster S of the invention 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. The booster piston 2, which is housed in the booster shell 1 so as to be able to reciprocate back and forth, has a central boss part 2a made of synthetic resin, and a disc part made of a thin steel plate that abuts the rear surface of a flange 3 integrally provided on the outer periphery of the boss part 2a. 2b, and this disc part 2
b is an annular locking protrusion 47 formed by bending its inner peripheral end rearward, a curled part 48 which bends its outer peripheral end inward to avoid contact with the diaphragm 4 described later, and a stepped portion described later. Short cylindrical portion 49 and its short cylindrical portion 4
The flange 3 is raised from the front surface except for the part 9.
It has an arc-shaped reinforcing rib 50 extending along the circumferential surface of the case.

The rolling diaphragm 4 superimposed on the rear surface of the disc portion 2b has beads 4a, 4 on its outer periphery.
b, and an annular locking groove 51 is provided on the front surface of the inner peripheral bead 4a, and the inner peripheral bead 4a is tightly fitted to the outer periphery of the center boss 2a, and the flange 3 It is brought into close contact with the rear surface, and the locking protrusion 47 is further engaged with the locking groove 51 . In this way, the inner circumferential bead 4a can ensure airtightness between the first and second working chambers A and B on two surfaces, the inner circumferential surface and the front surface, and is restrained from expanding in the radial direction by the locking protrusion 47. . 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, on the outer peripheral surface of the center boss 2a, an annular retaining member 5 made of a spring steel plate is attached to an elastic locking pawl 46 integral with the annular retaining member 5.
This holding member 5 cooperates with the flange 3 of the central boss portion 2a to clamp 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 tie rods 11 (see FIG. 5) pass through it.

Tie rod 1 is installed on the inner surface of the end wall of 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, so that the fixed end supports a 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. In addition, boss 20
A seal housing 23 is recessed in the outer end surface of the housing 23, and a seal member 25 for sealing the tie rod through hole 24 of the front shell 1A is provided in the housing 23.
is fitted.

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. The short cylindrical portion 49 consists of a large diameter portion 49b on the base end side and a small diameter portion 49a on the distal end side, and a synthetic resin protective ring 43 having approximately the same outer diameter as the large diameter portion 49b is fitted into the small diameter portion 49a. be done. The front surface of the protective ring 43 is the short cylindrical portion 4.
The small diameter portion 49 protrudes forward from the small diameter portion 49a of No.9.
It is designed to cover the tip of a.

The following sealing means is applied to the through hole 32 of the disc portion 2b.

That is, the tie rod 11 is surrounded by a bellows-shaped elastic boot 33 in the first working chamber A, and the front end 33a of the boot 33 is tightly fitted and fixed to the outer peripheral surface of the tie rod 11. Also, boots 33
The rear end portion 33b has an annular mounting groove 52 on the outer periphery,
The small diameter portion 4 of the stepped short cylindrical portion 49 is inserted into this mounting groove 52.
9a and the protective ring 43 are tightly fitted, and the boot 33 is removed.
The rear end portion 33b is fixed to the disk portion 2b. Thus, the rear end 33b of the boot 33 has an annular mounting groove 5.
By bringing the bottom surface and the rear side surface of 2 into close contact with the stepped short tube portion 49, airtightness between the first and second working chambers A and B can be ensured. Further, the protective ring 43 that covers the tip of the small diameter portion 49a of the stepped short cylindrical portion 49
This helps to prevent the leading edge of the annular mounting groove 52 from digging into the front side surface of the annular mounting groove 52. Thus, boots 33
Due to its elasticity, the through hole 32 can always be reliably sealed without interfering with the back and forth movement of the booster piston 2.

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, and these overlapping surfaces are connected to the through hole 34 of the diaphragm 4 that is penetrated by the tie rod 11. 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 2a 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 a positioning notch 36 and a positioning claw 7 that engage with each other.
Further, as shown in FIG. 4, a positioning notch 38 and a positioning protrusion 3 that engage with each other are provided at the connecting portion of the rear shell 1B and the outer peripheral bead 4b of the diaphragm 4.
9 is provided, and as shown in FIG.
A positioning recess 40 and a positioning protrusion 41 that engage with each other are provided on the overlapping surfaces of the diaphragm 4 and the diaphragm 4. Further, as shown in FIG. 5, two arcuate positioning notches 42 are provided symmetrically around the center axis on the outer periphery of the flange 3 of the central boss portion 2a, and these notches 42 are provided on the outer periphery of the flange 3 of the central boss portion 2a. The two short cylindrical parts 49 and the protective ring 43 are engaged. Furthermore, as shown in FIG.
and a positioning claw 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. 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 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 easily discharged through the gap g and the through hole 34 into the second working chamber B under atmospheric pressure, so that the discharge resistance of the air in the first working chamber A is reduced. The booster piston 2 can be easily operated manually without much effort.

As described above, according to the present invention, since the disk portion of the booster piston is made of a thin plate, it is possible to reduce the weight of the booster piston and, by extension, the booster.
In addition, since the through hole of the disc part that is penetrated by the tie rod is defined by the stepped short tube part integrally protruding from the front surface of the disc part, the rigidity of the through hole part of the thin disc part is reduced. can be prevented.

Further, a protective ring covering the tip of the small diameter portion is fitted to the outer periphery of the small diameter portion of the stepped cylindrical portion, and the small diameter portion and the protection ring are formed on the disk portion side end of the elastic boot surrounding the tie rod. Since it is elastically fitted into the annular mounting groove, it is possible to easily attach the end of the boot to the disc part, as well as to ensure that the connection between the annular mounting groove and the stepped short cylindrical part is radial and axial. A wide contact surface can be obtained to ensure airtightness of the end of the boot, and the protective ring prevents the tip edge of the small diameter part of the stepped short tube part from digging into the side wall of the annular mounting groove. Since this can be prevented, the annular mounting groove has the effect of improving the durability of the boot end.

[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. 5 and 6 are cross-sectional views taken along lines - and - of FIG. 1. A...First working chamber, B...Second working chamber, S...Boosting device, 1...Booster shell, 2...Booster piston, 2a...Center boss part, 2b...Disc part, 4...Diaphragm, 4a...Inner periphery Bead, 4b...Outer bead, 6...Negative pressure introduction pipe, 7...Input rod, 11...Tie rod, 32...Through hole in disc portion, 33...Stretchable boot, 33a...Front end as one end, 33b...Others Rear end portion as an end portion, 43...protective ring, 49...stepped short tube part, 49a...small diameter part, 49b...large diameter part, 52
...Annular mounting groove.

Claims (1)

[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 a booster piston that overlaps with the rear surface of the disc portion of the booster piston to connect the inner peripheral bead to the central boss portion of the booster piston and connect the outer peripheral bead to the rear surface of the disc portion of the booster piston. A first working chamber at the front is connected to a negative pressure source by a diaphragm attached to a peripheral wall of the booster shell, and is selectively communicated with the first working chamber or the atmosphere via a control valve linked to an input rod. and a second working chamber at the rear, and the front and rear end walls of the booster shell are connected via a tie rod that penetrates the disk portion of the booster piston,
In the negative pressure booster, one end of an elastic boot surrounding the tie rod is fitted into the tie rod, and the other end is fitted into a through hole of the disk portion penetrated by the tie rod. is composed of a thin plate, and the through hole of the disc part is defined by a stepped short cylindrical part integrally protruding from the front surface of the disc part,
A protective ring covering the tip of the small diameter portion is fitted onto the outer periphery of the small diameter portion of the stepped short cylindrical portion, and the small diameter portion and the protective ring are elastically inserted into the annular mounting groove formed on the outer circumferential surface of the other end of the boot. A negative pressure booster characterized by being fitted into a.