JPS6244841Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tandem brake booster, and more particularly to an improvement in the connecting portion between a cylindrical member connecting two front and rear pistons and a front piston.

The tandem brake booster includes two pistons, front and rear, connected by a cylindrical member, and a pair of diaphragms supported by these pistons, respectively, and a tandem brake booster is provided between the diaphragms and the diaphragms. 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 boosters, the front piston and the cylindrical member are connected by torsion, which has the disadvantage that torsional stress is applied to the diaphragm and the diaphragm is easily damaged. Furthermore, when the two are molded as one body, there is a drawback that the weight becomes heavy because the thickness of the plate is constant.

The present invention was developed in view of the above-mentioned drawbacks, and includes forming a cylindrical protrusion with a through hole on one side and a hole for receiving the protrusion on the other side at the joint between the front piston and the cylindrical member. To provide a tandem brake booster which facilitates assembly, reduces the weight of the device, and eliminates the risk of damage to the diaphragm by fitting these protrusions and holes and caulking them together. The purpose is to

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. Also, 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.

The driven rod 12 is inserted into the cylindrical member 6 from the front piston 3 side, and the operating rod 13 is inserted into the valve body 4 from the rear 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 (not shown) is provided at the tip of the operating rod 13, and controls communication and interruption between the pressure chambers C and D in accordance with the displacement of the operating rod 13. Note 1
4 is a pressure deformation member made of an elastic body interposed between the operating rod 13 and the driven rod 12, and the brake reaction force is applied to the brake pedal via the driven rod 12, the pressure deformation member 14, and the operation rod 13. transmitted to.

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 pressure chambers A, B, C, and D are connected to each other. The pressure is maintained at the same level and both pistons 3 and 5 do not displace. On the other hand, during a brake operation in which the operating rod 13 is displaced to the left in the drawing, the valve mechanism cuts off the communication between the pressure chambers C and D and introduces the atmosphere into the pressure chamber D. As mentioned above, pressure chamber C communicates with pressure chamber A through passage 10, and pressure chamber D communicates with pressure chamber B through passages 8a and 2a.
Therefore, the pressure chambers B and D into which atmospheric air is introduced by the operation of the valve mechanism 18, and the pressure chambers A and D, which are in communication with the negative pressure source via the operating pressure inlet 11,
A pressure difference is generated between the cylinder and the cylinder C, and this pressure difference causes the front and rear pistons 3 and 5 to displace, and as a result, the actuated rod 12 operates the master cylinder and performs a braking action. .

Here, the joint portion between the front piston 3 and the cylindrical member 6 will be explained in detail. FIG. 2a shows the state before coupling, and FIG. 2b shows the state after coupling. In the figure, 15 is a flange provided on the front side of the cylindrical member 6, and 16 is a plurality of flanges provided at predetermined positions of this flange 15. It is a cylindrical protrusion. This protrusion 16 is formed by burring molding or the like, and a through hole 17 is formed in the cylindrical portion. Reference numeral 18 denotes an annular concave portion formed on the rear surface side of the flange 15 by protruding the base of the flange 15 forward, and a thick wall portion provided on the inner circumferential edge of the diaphragm 7 is located within this concave portion 18. 19 are accommodated. On the other hand, each of the cylindrical projections 16 is provided at the joint 20 that is connected to the flange 15 on the inner peripheral side of the front piston 3.
A circular hole 21 into which this protrusion can be inserted into a position corresponding to
are drilled in each. After each of these cylindrical projections 16 is inserted into each circular hole 21, both the front piston 3 and the cylindrical member 6 are coupled together by caulking. By making the caulking connection in this way, assembly can be performed extremely easily.
Furthermore, in addition to eliminating the risk of damage to the diaphragm caused by the torsional connection, the piston 3
Since the piston 3 can be made thinner than when the piston 3 and the cylindrical member 6 are integrally molded, the weight of the device can be reduced. Moreover, it is possible to obtain a product with stable quality at a lower cost than by means such as welding.
Further, by forming the cylindrical projection 16 as a through hole 17, it can also function as a passage for discharging air accumulated between the piston 3 and the diaphragm 7 when the diaphragm 7 is assembled.

The inner peripheral end of the front piston 3 is extended so as to be located within the opening of the recessed portion 18 in a state where the piston 3 and the cylindrical member 6 are joined.
Moreover, the tip 22 is bent toward the inside of the concave portion 18 . An engagement groove 23 is formed in the thick walled portion 19 of the inner circumference of the diaphragm 7, and the engagement groove 23 and the protruding engagement portion 22 at the tip of the piston 3 engage with each other, so that the diaphragm 7 is attached to the piston 3. I'm trying to support it. Therefore, by pressing the thick portion 19 of the diaphragm 7 and inserting it into the recessed portion 18, the diaphragm can be easily engaged and supported.

It goes without saying that the bottomed cylindrical projection 16 of this embodiment can be formed by known means such as pressing.

As described above, according to the present invention, it is possible to easily assemble a tandem brake booster, and moreover, it is possible to provide an inexpensive and stable quality device. In particular, in the present invention, a plurality of cylindrical protrusions having through holes are formed on either the front piston or the flange of the cylindrical member, and holes through which each of these protrusions can be inserted are bored on the other side. Since each protrusion and each hole are fitted and caulked together, the through hole of the cylindrical protrusion functions as a discharge passage for air accumulated between the diaphragm and the piston, especially when the piston is closed before negative pressure is introduced. This has the effect of preventing the diaphragm from bending or becoming jammed with the shell during actuation or sudden actuation.Moreover, the caulking connection described above is a double-sided method that requires plating after welding, unlike conventional welding connections. Not only can the work be omitted, there is no need for post-treatment consideration for rust prevention such as pickling the plating liquid that has penetrated into the welded joint, and it has good strength as a piston of a booster with simple assembly work. It also has the advantage of retaining functionality.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view showing the entire tandem brake booster according to an embodiment of the present invention, and FIG.
Figures a and b are sectional views showing the state before and after the front piston and the cylindrical member are connected, respectively. 3: Front piston, 5: Rear piston,
6: cylindrical member, 15: flange of cylindrical member, 1
6: Cylindrical projection, 21: Front piston hole.

Claims (1)

[Scope of utility model registration request] The piston includes two front and rear pistons that move forward and backward in response to a pressure difference, and a cylindrical member that connects the two pistons, and the front piston is fixed to a flange formed at the front end of the cylindrical member. In the tandem type brake booster, a plurality of cylindrical protrusions having through holes are formed on either the front piston or the flange of the cylindrical member, and holes through which each of these protrusions can be inserted are bored on the other side. A tandem type brake booster characterized in that each of these protrusions and each hole are fitted and connected by caulking.