JPS635977Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a pneumatic booster used in a vehicle brake system or the like.

In the case of a pneumatic booster, the main body, which is composed of a front shell and a rear shell, is divided into two chambers, a front chamber and a rear chamber, by a diaphragm and a power piston attached to the diaphragm. When the input shaft is operated to create a pressure difference between the two chambers, forward thrust acting on the power piston is transmitted to the input shaft.

By the way, in the case of such a booster, both shells are strongly pressed from the front and rear directions to improve the bonding strength, while at the same time, both shells extend in the front and rear direction to form an attachment part to the vehicle body or the master cylinder. A bolt is provided that passes through the. That is, this bolt passes through the diaphragm-power piston assembly in an airtight and slidable manner, and its front end extends toward the front of the front shell, and its rear end extends toward the rear of the rear shell. Usually, a plurality of these bolts are provided at intervals in the circumferential direction of the output shaft.

However, with conventional boosters of this type,
Since only one large coil-shaped return spring that urges the power piston rearward is fitted onto the output shaft, the following problems have arisen. That is, although this coiled return spring is interposed between the front shell and the diaphragm power piston assembly, the spring force cannot be evenly distributed and transmitted to the diaphragm penetrating portion of each bolt, Therefore,
When the power piston returns to the rear, it tends to tilt, and as a result, the diaphragm of the bolt
Seal leakage was likely to occur at the portion that penetrated the power piston assembly. For this reason, the return spring has a conical shape that expands in diameter toward the power piston, so that spring force is applied as evenly as possible to the penetrating portion, but it is still not sufficient, and the return spring Since it has the above-mentioned special shape, it is not preferable in terms of cost reduction.

The present invention solves the above-mentioned problems and is characterized in that each bolt is fitted with a coiled return spring.

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, a main body 1 is constructed by combining a front shell 1A and a rear shell 1B.
It is divided into two rooms: a rear room 5 and a rear room 5. This front chamber 4 is connected to an intake pipe (not shown) of the engine 2 via a negative pressure introduction pipe 6, and in the assembly A of the above-mentioned 2 and 3, communication and isolation between the two chambers 4 and 5 are provided. A valve body 7 containing a built-in valve mechanism for this purpose is integrated. When the input shaft 8 extending into the valve body 7 is pushed forward, the valve mechanism is switched, and the pressure difference between the two chambers 4 and 5 (in the embodiment, the front chamber 4 becomes a negative pressure, and the rear chamber becomes a negative pressure). 5
becomes atmospheric pressure), and the forward thrust generated in the power piston 3 at this time is transmitted to the output shaft 9. It should be noted that the parts described above are the same as those in the prior art, so a more detailed explanation will be omitted.

Around the output shaft 9, a plurality of (two in the embodiment) bolts 10 as shaft-like coupling members are arranged at equal intervals in the circumferential direction with the output shaft 9 as the center. The bolts 10 each extend in the front-rear direction and pass through the assembly A in an airtight and slidable manner using the seal member 13, with their front ends 10a extending toward the front of the front shell 1A, and their rear ends 10b extending toward the rear shell. It extends to the rear of 1B. This bolt 10
In collaboration with Natsuto 11 and others, both Ciel 1A and 1B
is pressed from the front and rear directions, a master cylinder (not shown) is attached to the main body 1 using the front end 10a, and the main cylinder 1 is fixed to the vehicle body (not shown) using the rear end 10b. It's summery.

A coil-shaped return spring 12 is fitted around the outer periphery of each bolt 10, respectively. Each return spring 12 has the same diameter and the same spring force over its entire length, and its front end is seated on the front shell 1A and its rear end is seated on the assembly A. Assembly A is energized backwards.

Therefore, according to the present invention, after the booster is activated (the assembly A moves forward), if the pressing force of the input shaft 8 is released, the assembly A is returned to the rear by the return spring 12. However, since each return spring 12 is used independently at the sliding part between assembly A and bolt 10, in other words, an urging force that tilts assembly A acts on assembly A. Therefore, seal leakage does not occur at the above-mentioned sliding portion. Furthermore, since the assembly A is not tilted, the sliding resistance of the sliding portion is reduced, and smooth back and forth movement of the assembly A is ensured.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which FIG. 1 is a sectional view taken along the line in FIG. 2, and FIG. 2 is a sectional view taken along the line in FIG. 1. 1...Body, 1A...Front shell, 1B...
...Rear shell, 2...Diaphragm, 3...Power piston, 4...Front chamber, 5...Rear chamber,
8...Input shaft, 9...Output shaft, 10...Bolt (shaft-shaped coupling member) 12...Return spring.

Claims (1)

[Claim for Utility Model Registration] A diaphragm-power piston assembly, which is provided in a floating state and consists of a diaphragm and a power piston attached to the diaphragm, forms a front chamber and a rear chamber within the main body composed of a front shell and a rear shell. The pneumatic type is defined into two chambers, and when the input shaft is actuated to create a pressure difference between the two chambers, the forward thrust generated in the power piston is transmitted to the output shaft. In the booster, a shaft-shaped coupling member extending in the front-rear direction that passes through the diaphragm-power piston assembly in an airtight and slidable manner and extends to the outside of both shells is arranged in a circumferential direction of the output shaft. A plurality of coil return springs are provided at intervals, and each of the shaft-shaped coupling members is provided with a coil-shaped return spring having the same spring force in order to bias the diaphragm-power piston assembly rearward with an even force. A pneumatic booster characterized by being fitted.