JPH0611276Y2 - Pneumatic booster - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a pneumatic booster used in a brake system of an automobile or the like.

(Prior Art) A pneumatic booster is designed to increase the pedal effort of the brake pedal by using the negative pressure of the intake pipe of the engine and output it to the master cylinder so that a large pedal effort can be generated with a small pedal effort. is there.

An example of a conventional pneumatic booster will be briefly described with reference to FIG. 3. A shell body 3 is composed of a front shell 1 and a rear shell 2, and the inside of the shell body 3 is divided into the two shells 1 and 2 on the outer peripheral side. A constant pressure chamber 6 and a variable pressure chamber 7 are defined by a diaphragm 5 which is sandwiched and whose inner peripheral side is fixed to the power piston 4. The constant pressure chamber 6 is connected to a negative pressure source such as an intake manifold (not shown) and is always in a negative pressure state.

A valve mechanism 8 is provided on the rear shell 2 side, and the valve mechanism 8 communicates with the variable pressure chamber 7 and the atmosphere by depressing a brake pedal (not shown) to move the input shaft 9 forward. Has a function of communicating the constant pressure chamber 6 and the variable pressure chamber 7 by separating the
Due to the communication between the variable pressure chamber 7 and the atmosphere, a pressure difference is generated between the variable pressure chamber 7 and the constant pressure chamber 6 in the negative pressure state, and the pressure difference causes the power piston 4 to move forward to give a thrust force to the output shaft 10 to output. axis
The operating force is transmitted from 10 to the master cylinder M, the pressure difference between the constant pressure chamber 6 and the variable pressure chamber 7 is eliminated, and the return spring 11 returns the power piston 4 to its original position.

By the way, in this pneumatic booster, a master cylinder M is attached by a master cylinder attachment bolt (hereinafter referred to as an attachment bolt) 12 fixed to the front shell 1. The mounting bolts 12 are fixed by forming through holes 1a and 13a in the front shell 1 and the stiffener 13 provided inside to reinforce the front shell 1 and forming an annular projection projection on the shaft side. Mounting bolt 12 having a head 12c having an outer peripheral projection 12b and an outer peripheral projection 12b.
And is welded by projection welding.

The outer peripheral projection 12b of the mounting bolt 12 is designed to prevent the tip of the projection projection 12a from melting during welding so as not to flow in the outer peripheral direction, and to prevent the head 12c of the mounting bolt 12 from contacting the stiffener 13. Increase the area and master cylinder M
This is to disperse the stress due to the reaction force from.

(Problems to be solved by the invention) By the way, in order to reduce the weight of automobiles and the like, it has been strongly demanded to reduce the weight of the pneumatic booster, and accordingly, the plate of the front shell 1 of the pneumatic booster. There is a tendency to reduce the thickness.

However, in the pneumatic booster, a large force is applied in the axial direction from the master cylinder M as a reaction force of the operating force transmitted to the master cylinder M, and this reaction force is applied to the shell body 3 via the mounting bolt 12. Therefore, stress concentrates on the mounting portion of the mounting bolt 12, and if the plate thickness of the shell 1 is thinned, the strength of the mounting portion decreases, so that there is a problem that the concentrated stress causes deformation or cracking. .

In order to solve this problem, the head 12 of the mounting bolt 12
Although it is conceivable to increase the contact area between the c and the stiffener 13, it is necessary to increase the width of the outer peripheral projection 12b or increase the melting margin of the injection projection 12a for that purpose. However, in this case, the weight of the mounting bolt 12 increases, which hinders the weight reduction of the pneumatic booster.

In addition, as another example of the conventional pneumatic booster, a full-scale shokai 62-5 is used.
There is one shown in Japanese Patent No. 6478. This pneumatic booster
An annular protrusion 5d is formed on the head of the mounting bolt 5, and the head of the mounting bolt 5 is fixed to the reinforcing plate 7 by projection welding. In this pneumatic booster, the height of the annular protrusion 5d and the depth of the groove of the reinforcing plate 7 that fits into this annular protrusion 5d are unknown, and the height of the annular protrusion 5d is the groove of the reinforcing plate 7. If it is larger than the depth of, the protrusion 5d on the head of the mounting bolt 5
When the other portions are separated from the reinforcing plate 7 and the depth of the groove of the reinforcing plate 7 is larger than the height of the annular protrusion 5d, the welding strength between the head of the mounting bolt 5 and the reinforcing plate 7 is high. There is a risk that the adhesive strength may be lowered and reliable fixation may not be achieved.

Another example of a conventional pneumatic booster is disclosed in Japanese Utility Model Laid-Open No. 58-74612. This pneumatic booster forms an annular projection projection that is concentric with the shaft on the stiffener side of the head of the bolt, and forms an annular projection that is larger in diameter and concentric than the projection projection, The height of the projection protrusion is set higher than that of the annular protrusion by the amount of melt during welding.
However, in this pneumatic booster, the stiffener has a flat plate shape, and it is not possible to expect a large improvement in the strength of the stiffener itself, and further, an improvement in the strength of the entire apparatus due to the improvement in the strength of the stiffener.

The present invention has been made in view of the above circumstances, and the stress applied to the mounting portion of the master cylinder mounting bolt in the front shell is dispersed to increase the strength, and the master cylinder mounting bolt is securely fixed to the stiffener. Can be done
Another object of the present invention is to provide a pneumatic booster capable of improving the strength of the stiffener and the strength of the entire apparatus.

(Means for Solving the Problems) A pneumatic booster of the present invention has a front shell and a stiffener that reinforces the front shell and has an insertion hole formed therein, and the insertion hole is provided with a shaft portion and a screw portion. In a pneumatic booster in which a master cylinder mounting bolt consisting of a substantially flat plate-shaped head that is connected to the shaft is inserted, and the head and the stiffener are fixed by welding, in the front shell side of the stiffener, An abutment portion for the front shell is formed in a double annular shape with the insertion hole as a center, and an annular portion forming a concentric circle with the insertion hole at a portion between the double annular abutment portions on the head side of the stiffener. The shaft is formed by bending the convex portion, and on the stiffener side of the head, the diameter is smaller than that of the annular convex portion, and the height is set higher than that of the annular convex portion by the amount of melting during welding. Concentric annular pro Characterized in that the formation of the Ekushon projections.

(Operation) According to this structure, when the projection protrusion is melted by welding, the annular protrusion of the stiffener comes into contact with the head of the master cylinder mounting bolt, so that the outer peripheral projection seat is formed on the head of the master cylinder mounting bolt. It is possible to secure a desired contact area by reducing the weight as compared with the above. Since the stiffener is formed into an uneven shape by forming an annular convex portion on the stiffener, rigidity and strength of the stiffener itself are improved, and accordingly, the plate thickness of the stiffener can be reduced. Further, since the stiffener having increased strength brings the double annular contact portion into contact with the front shell, the stiffener can be integrated with the front shell, whereby the strength of the entire apparatus can be improved.

The projection projection melted by welding fills the space between the head and the stiffener in the annular projection, which further increases the contact area and further disperses the stress due to the reaction force from the master cylinder. The thickness of the shell can be reduced.

The height of the projection protrusion is set to be higher than that of the annular protrusion, and the projection protrusion and the stiffener come into contact with each other during welding.

(Example) Next, the Example of this invention is described based on drawing. 1 is an enlarged view showing the mounting structure before the mounting bolts are welded, FIG. 2 is an enlarged view showing the state after welding, and this embodiment shows mounting of the mounting bolts. Since only the structure is different from the conventional structure, other parts will be described with reference to FIG.

First, in FIG. 1, the front shell (corresponding to the front shell 1 in FIG. 3) 14 and the stiffener (corresponding to the stiffener in FIG. 3) 15 for reinforcing the front shell 14 are
Insertion holes 14a and 15a through which the mounting bolt 16 is inserted are formed, respectively.

In the vicinity of the insertion hole 14a of the front shell 14, the stiffener 1
An annular projection projection 14b for fixing 5 is formed concentrically with the insertion hole 14a so as to project toward the stiffener 15 side, and the stiffener 15 has an insertion hole 15a and an annular projection 15b concentric with the shell. It is bent and formed so as to protrude inward of the main body.

In addition, a projection 16b is formed in a ring shape on the shaft side of the head 16a of the mounting bolt 16. The protrusion amount of the annular protrusion 15b of the stiffener 15 is set to be smaller than the height of the projection protrusion 16b.

The upper surface 15c of the annular protrusion 15b of the stiffener 15 is a mounting bolt.
In order to secure the area of contact with the head 16a of 16 as large as possible, the space for accommodating the melted projection projection 16b at the tip thereof during welding is formed to a minimum.

Then, when projection welding is performed in combination as shown in FIG. 1, the projection protrusion 14b of the front shell 14 is welded to the stiffener 15, and the projection protrusion 16b formed on the head 16a of the mounting bolt 16 is stiffener 15. Is welded to. At this time, projection projection
The head 16a is melted until the head 16a comes into contact with the annular protrusion 15b of the stiffener 15 (the state shown in FIG. 2).

In this way, when the mounting bolt 16 is fixed, the head 16a of the mounting bolt 16 and the annular convex portion 15b of the stiffener 15 come into contact with each other, and the head 16a and the stiffener 15 are made by melting the projection protrusion 16b. Therefore, the contact area can be increased and the stress due to the reaction force from the master cylinder M can be dispersed. The stiffener 15 also has an uneven shape, so the stiffener 15
The rigidity in the vicinity of the insertion hole 15a itself is also improved. This allows
The strength of the mounting portion of the mounting bolt 16 is increased.

(Effect of the Invention) As described in detail above, according to the present invention, when the projection projection is melted by welding, the annular projection of the stiffener comes into contact with the head of the master cylinder mounting bolt. It is possible to reduce the weight and secure a desired contact area as compared with the type in which the outer peripheral protruding seat is formed. Since the stiffener has an annular convex portion and the stiffener has an uneven shape, the rigidity and strength of the stiffener itself is improved, and the plate thickness of the stiffener can be reduced accordingly, and the weight of the stiffener and thus the entire device can be reduced. it can. Further, since the stiffener having increased strength brings the double annular contact portion into contact with the front shell, the stiffener can be integrated with the front shell, whereby the strength of the entire apparatus can be improved.

The projection projection melted by welding fills the space between the head and the stiffener in the annular projection, which further increases the contact area and further disperses the stress due to the reaction force from the master cylinder. The thickness of the shell can be reduced, and the front shell, and thus the entire device, can be made even lighter.

The height of the projection projection is set higher than that of the annular projection, and the projection projection and the stiffener come into contact with each other during welding, so that the master cylinder mounting bolt can be securely fixed to the stiffener.

In addition, since the rigidity of the stiffener is improved, the adhesion of welding can be improved and the airtightness can be improved.

[Brief description of drawings]

FIG. 1 is an enlarged view showing a state before fixing a mounting bolt according to an embodiment of the present invention, and FIG. 2 is an enlarged view showing a state in which the mounting bolt is fixed by welding from the state shown in FIG. FIG. 1 is a vertical cross-sectional view showing the entire conventional pneumatic booster. 14 …… Front shell 14a …… Insertion hole 15 …… Stiffener 15a …… Insertion hole 15b …… Annular protrusion 16 …… Master cylinder mounting bolt 16a …… Head

Claims (1)

[Scope of utility model registration request] 1. An insertion hole is formed in a front shell and a stiffener that reinforces the front shell, and the insertion hole includes a shaft portion having a screw portion and a substantially flat head portion connected to the shaft portion. In a pneumatic booster in which a master cylinder mounting bolt is inserted and the head and the stiffener are fixed by welding, a contact portion for the front shell is provided on the front shell side of the stiffener, and the insertion hole is provided. The stiffener is formed in a double annular shape as a center, and in a portion between the double annular contact portions on the head side of the stiffener, an annular convex portion forming a concentric circle with the insertion hole is formed by bending, and the stiffener of the head portion. On the side, the diameter is smaller than that of the annular projection, and the height is set higher than that of the annular projection by the amount of melt during welding, and a projection projection that is concentric with the shaft is formed. Characterizing Pneumatic booster.