JPH0133416Y2 - - Google Patents

Description

[Detailed description of the invention] The invention relates to a tandem brake booster.
In particular, it relates to improvements in the joint between the front piston and the diaphragm.

A tandem brake booster includes two front and rear pistons connected by a cylindrical member, and a pair of diaphragms supported by each of these pistons. The interior of the shell is divided by a center plate, forming four pressure chambers, and a pressure difference is created between these pressure chambers, and this pressure difference displaces both pistons to perform a braking action. In conventional devices, in order to support the diaphragm on the piston, a separate support member is fixed to the piston, and the diaphragm is held between the support member and the piston.

The purpose of the present invention is to provide a tandem brake booster that does not require a separate support member as described above, has an extremely simple configuration, and can be easily assembled. A recess capable of accommodating the inner peripheral edge of the diaphragm is formed in the cylindrical member connecting the rear piston, and the inner peripheral end of the front piston is positioned within this recess, while the inner peripheral end of the piston is located at the inner peripheral edge of the diaphragm. An engagement groove is formed to engage with the piston, and the inner circumferential edge of the diaphragm is inserted into the recess to engage and support the diaphragm with the piston.

Hereinafter, the present invention will be explained based on illustrated embodiments. In FIG. 1, 1 is a front shell, 2 is a rear shell, and inside a sealed container composed of both shells 1 and 2 is a front piston 3 made of a plate.
and a rear piston 5 integrated with the valve body 4 are arranged in series, and both pistons 3 and 5 are connected by a cylindrical member 6. Further, 7 and 8 are diaphragms that divide the inside of the container together with the front and rear pistons 3 and 5, respectively, 9 is a center plate that forms a small chamber on the front piston 3 side between the pistons 3 and 5, and the cylindrical member 6 is configured to be able to slide on the center plate 9 while maintaining airtightness. In this way, pressure chambers A, B and C, D are formed before and after the two front and rear pistons 3, 5, respectively, and these pressure chambers A and C communicate with each other through the internal passage 10 of the cylindrical member 6. The pressure chambers B and D are also connected to the passage 8a of the diaphragm 8 and the passage 2 of the rear shell 2.
They communicate with each other by a. Reference numeral 11 denotes an operating pressure inlet opening into the pressure chamber A, and is connected to a negative pressure generating section of the vehicle engine.

12 is a driven rod inserted into the cylindrical member 6 from the front piston 3 side, and 13 is an operating rod inserted into the valve body 4 from the rear part of the rear piston 5. The driven rod 12 is not shown in the figure. The operating lever 13 is respectively linked to a brake pedal (not shown), and a master cylinder (not shown). A well-known valve mechanism is provided at the tip of the operating rod 13, and the pressure chamber C and the pressure chamber D are adjusted according to the displacement of the operating rod 13.
Performs communication cutoff control with. Note that 14 is the operating rod 1
3 and the driven rod 12, and the brake reaction force is transmitted to the brake pedal via the driven rod 12, the pressurized deformation member 14, and the operating rod 13. .

In this tandem type brake booster, in the illustrated state where no pedal force is applied to the brake pedal and the operating rod 13 is not displaced, the valve mechanism connects the pressure chambers C and D, so that all the pressure chambers A, B, C, and D are connected to each other. Both pistons 3 and 5 are kept at the same pressure and do not displace. On the other hand, during a brake operation in which the operating rod 13 is displaced to the left in the figure, the valve mechanism cuts off communication between the pressure chambers C and D and introduces atmospheric air into the pressure chamber D. As mentioned above, the pressure chamber C communicates with the pressure chamber A through the passage D,
Since the pressure chamber D communicates with the pressure chamber B through the passages 8a and 2a, the pressure chambers B and D into which atmospheric air is introduced by the operation of the valve mechanism, and the operating pressure inlet 11
A pressure difference occurs between the pressure chambers A and C, which are in communication with a negative pressure source through the Braking is performed by operating the master cylinder.

Here, the joint portion between the front piston 3, the cylindrical member 6, and the diaphragm 7 will be explained in detail. The cylindrical member 6 is provided with a flange 15 on its front side, and is coupled to the front piston 3 at this flange portion 15. The base 15a of the flange 15 is projected forward, and as a result, an annular recess 16 is formed on the rear side of the base 15a. (See Figures 1 and 2) On the other hand,
Front piston 3 fixed to flange 15
is extended until its inner peripheral edge is positioned approximately at the center of the radial width d of the annular recess 16, and its tip is bent into the recess 16 to form an engaging portion 17. Further, on the inner periphery of the diaphragm 7, a thick wall portion 18 facing forward is provided to correspond to the recessed portion 16, and the engaging portion 1 is formed in the thick wall portion 18.
An annular engagement groove 19 that engages with 7 is carved. Since the device of this embodiment is constructed as described above, when assembling, the front piston 3 and the cylindrical member 6 are integrated by spot welding or the like, and then the diaphragm 7 is pressed in the direction of the arrow in FIG. By doing so, when the thick portion 18 is inserted into the recessed portion 16, the engaging portion 17 and the engaging groove 19 are engaged, and the diaphragm 7 is easily fixed to the piston 3. If the diaphragm 7 is fixed in place, there is no risk that the diaphragm 7 will come off even if this device is used without a vacuum during air bleeding or the like and a reverse pressure is applied. Furthermore, when disassembling the diaphragm, it can be easily removed manually by pulling the diaphragm locally. Note that the engaging part 17 on the inner circumference of the piston 3 is not limited to the one bent into the recessed part 16 as described above, but can also be bent into the recessed part 16, such as with the tip folded back as shown in FIG. Any convex shape that can be engaged with the engagement groove 19 of the diaphragm 7 to be inserted may be used.

FIGS. 4 and 5 show an example of a connecting portion between the piston 3 and the cylindrical member 6, in which a plurality of cylindrical protrusions 20 are formed on the flange 15 of the cylindrical member 6,
On the other hand, small holes 21 are bored in the inner peripheral side joint portion of the piston 3 so as to correspond to each of these protrusions 20. Then, each of these protrusions 20 and each of the small holes 21 are fitted and caulked together. By connecting the piston 3 and the cylindrical member 6 by caulking in this manner, assembly can be performed extremely easily. The cylindrical protrusion 20 may be formed into a through hole 22 by burring molding (see Fig. 4a), or a bottomed cylindrical protrusion 20 protruding into a cylindrical shape by press working (see Fig. 4a).
(see Figure a). When the inside of the protrusion 20 is formed as a through hole 22, when the diaphragm 7 is disposed, it also functions as a passage for discharging air accumulated between the piston 3 and the diaphragm 7.

As described above, according to the present invention, the tandem brake booster can be easily assembled and disassembled with an extremely simple configuration.

Particularly, in the present invention, the base of the flange is made to protrude forward to form an annular recess on the rear surface in which the inner peripheral edge of the diaphragm can be accommodated, and the inner peripheral end of the front piston is made to protrude into the recess to engage the protruding part. The inner circumferential edge of the diaphragm is formed with an engaging groove that engages with the engaging portion, and the protruding base of the flange faces the inner circumferential side of the front shell. Therefore, there is no risk of torsional force being applied to the diaphragm as in the case of conventional bayonet connection of the piston to the cylindrical member or screw fastening with a nut, and the bent and protruding flange base is strong. It is reinforced and can function as a stopper against the inner peripheral side of the front shell during the full stroke of the piston, which has the effect of achieving a significant reduction in the axial dimension of the device.

[Brief explanation of the drawing]

Figures 1 to 5 all show embodiments of the present invention, Figure 1 is a sectional view showing the entire tandem brake booster, and Figures 3 to 5 are diagrams of other embodiments. FIG. 2 is a sectional view showing the same part as FIG. 2; 3... Front piston, 5... Rear piston, 6... Cylindrical member, 7... Front diaphragm, 8... Rear diaphragm, 15... Flange of tubular member, 16... Annular recess, 17... Projection engaging portion, 18...Diaphragm inner peripheral edge, 19...
Engagement groove.

Claims (1)

[Scope of utility model registration request] Two pistons made up of front and rear plates that move forward and backward in response to a pressure difference, and a cylindrical member made of a plate provided at the connection part of both pistons;
a pair of diaphragms that are respectively supported by the pistons and partition the inside of the shell; the front piston is fixed to a flange formed at the front end of the cylindrical member; and the inner peripheral edge of the front diaphragm is In a tandem brake booster supported at a base of a flange, the base of the flange projects forward to form an annular recess capable of accommodating the inner peripheral edge of the diaphragm on the rear surface, and the inner peripheral end of the front piston. is made to protrude into this recessed part to form a protruding engagement part, and an engagement groove that engages with this engagement part is carved on the inner peripheral edge of the diaphragm, and the protruding base of the flange is inserted into the front side shell. A tandem type brake booster characterized in that the inner circumferential side of the tandem brake booster is arranged opposite to each other.