JPH0230380Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air pressure booster for use in automobiles, which utilizes negative pressure in the intake manifold of an engine to reduce the force applied to the brake pedal.

Generally, as shown in Fig. 1, a pressure booster has a structure in which a constant pressure chamber 2 and a variable pressure chamber 3 are connected to the engine intake manifold through a communication pipe 1 and are maintained at a negative pressure. When the brake pedal is stepped on, the push rod 4 moves to the left in the figure and operates the air valve 5, etc., and the continuity between the constant pressure chamber 2 and the variable pressure chamber 3 is immediately cut off, and at the same time, the external pressure flows into the constant pressure chamber 3. be introduced. And power piston 6
is moved to the left in the figure due to the pressure difference, creating a boosting effect.

By the way, in this pressure booster, the front shell 7 forming the constant pressure chamber 2 and the rear shell 8 forming the variable pressure chamber 3 have their peripheral edges 7a,
8a are butted against each other and assembled to each other by a connecting member (connecting rod) 9, and the distance L 1 between the attachment parts of both shells 7 and 8 in the connecting member 9 is L ₁ (as shown in FIG. 2). is the primary assembly distance L ₂ of both shells 7, 8 in a state where both shells 7, 8 are simply butted together (each shell 7, 8 shown in Fig. 2).
It is set almost equal to the installed thickness l (sum of l ₁ and l ₂ ) in the free state (uninstalled state). In this conventional device, when the brake pedal is operated and atmospheric pressure is introduced into the variable pressure chamber 3 and a differential pressure is generated between the two shells 7 and 8, the two shells 7 and 8 are caused to move as shown by the dashed line in the figure. transforms into For this reason, the mounting portion 7 of the master cylinder 10 of the front shell 7
b, or the attachment part 8 of the rear shell 8 to the vehicle
A problem arises in that concentrated stress acts near b, etc., and if this deformation is repeated in both shells 7 and 8, fatigue failure may occur.

The present invention abuts the front shell and rear shell along their entire circumference at their peripheral edges, and also makes the distance between the attachment parts of the connecting member smaller than the distance between the attachment parts of both shells when they are simply butted together. By setting it short and installing both shells, the above conventional problems have been solved.
It is an object of the present invention to provide a pressure booster which can significantly improve durability by relieving stress generated in both shells since initial deflection is given to both shells in advance.

Hereinafter, the present invention will be explained based on the drawings.

The barometric pressure booster of the present invention has the same basic structure as conventional devices, and as it will be repeated,
As an example is shown in FIG. 1, a front shell 7 and a rear shell 8 form a constant pressure chamber 2 and a variable pressure chamber 3, respectively, and are assembled to each other by a connecting member 9 by abutting their peripheral edges 7a and 8a against each other. The connecting member 9 has one end 9a abutting and engaging with the inner surface of the opposing wall of the rear shell 8, and a threaded portion of the other end 9b penetrating the opposing wall of the front shell 7 and being attached to the master cylinder 10, The distance L ₁ between the attachment parts of both shells 7 and 8 in this connecting member 9 is the distance L ₂ between the attachment parts of both shells in a state where both shells 7 and 8 are simply butted together (in the free state of each shell 7 and 8). The installation thickness is set to be shorter than the sum of l ₁ and l ₂ ). As a result, the opposing walls of both shells 7 and 8 are brought close to each other, and both shells 7 and
8 is given an initial deflection of about 0.6 to 3 mm in the axial direction of the connecting member 9.

The air pressure booster configured as described above has the same boosting effect as conventional devices to reduce the force applied to the brake pedal. At that time, a pressure difference occurs between the constant pressure chamber 2 and the variable pressure chamber 3, and both shells 7 and 8 try to deform due to this pressure difference, but both shells 7 and 8 have an initial deflection of about 0.6 to 3 mm in advance. is provided, this deformation is kept to a minimum, and the attachment portion 7b of the master cylinder 10 of the front shell 7 and the attachment portion 8 of the rear shell 8 to the vehicle are
This prevents concentrated stress from occurring at b.

Note that FIG. 3 shows another type of air pressure booster, and the present invention can also be applied to such a type.

As described above, in the air pressure booster of the present invention, when assembling the front shell and rear shell, the distance between the attachment parts of the connecting member is determined relative to the distance between the attachment parts when both shells are simply butted together. Since the initial deflection is given to both shells in advance, even if undesirable stress is concentrated on both shells due to the operation of the device, this can be alleviated, and the durability of the device can be greatly improved. Further, by applying the present invention to a booster having a structure in which a front shell and a rear shell are abutted against each other over the entire circumference, it is possible to prevent stress concentration on the abutting portion due to the provision of the initial deflection.
Furthermore, since the structure of the device is the same as the conventional one, it can be implemented extremely easily without requiring any special modifications.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an example of the air pressure booster, and Fig. 2 is a diagram for explaining the features of the air pressure booster of the present invention, where a is the distance between the attachment parts of the connecting member, and b is the front shell. and c indicate the mounting thickness of the rear shell, respectively. Further, FIG. 3 is a sectional view showing another type of air pressure booster. 2... constant pressure chamber, 3... variable pressure chamber, 7... front shell, 8... rear shell, 9... connecting member,
L ₁ ... distance between mounting parts, L ₂ ... primary assembly distance.

Claims (1)

[Scope of utility model registration request] In an air pressure booster in which a front shell and a rear shell form a constant pressure chamber and a variable pressure chamber, their circumferential edges abut against each other over the entire circumference, and are assembled to each other by a connecting member, the circumferential edges of the front shell and rear shell are The distance between the attaching parts of the connecting member is set shorter than the distance between the attaching parts of both shells when they are simply butted together, and the connecting member brings the opposite walls of both shells closer to each other so that both shells can be attached in the axial direction of the connecting member. A pressure booster characterized by assembling both shells with an initial deflection of .