JP2544875Y2 - Negative pressure booster - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a vacuum booster used for a brake booster or the like, and in particular, a vacuum booster in which an output shaft is prevented from coming off by a retainer. It is about.

(Prior Art) As shown in FIG. 3, a general brake booster 01 utilizing a conventional negative pressure has an internal space partitioned into a constant pressure chamber 03 and a variable pressure chamber 04 by a power piston 02. It has a front shell 05 and a rear shell 06, and has an output shaft 07 that penetrates the front shell 05 airtightly and slidably to project from the inside of the shell to the outside. As shown in detail in FIG. 4, the rear end of the output shaft 07 is formed as a cylindrical portion 07a, and this cylindrical portion 07a is located at the center of the front end of the valve body 08 forming a part of the power piston 02. It is slidably fitted to the formed cylindrical projection 08a. In that case, a reaction disk 09 is interposed between the output shaft 07 and the protruding portion 08a in the cylindrical portion 07a. In addition, the output shaft
07 has a retainer 0 so that it engages the rear cylindrical portion 07a.
The retainer 010 receives the elastic force of the return spring 011 and constantly urges the output shaft 07 (further, the valve body 08 and the power piston 02) rearward. The retainer 010 serves as a stopper for preventing the output shaft 07 from dropping off from the booster 01.

Such a brake booster 01 includes a brake pedal 01
When the input shaft 013 is advanced by stepping on 2, the control valve (not shown) is switched and the atmosphere is introduced into the variable pressure chamber 04, so that a pressure difference is generated between the variable pressure chamber 04 and the constant pressure chamber 05. As a result, the power piston 02 operates, and the piston of a brake master cylinder (not shown) operates via the output shaft 07.

(Problems to be Solved by the Invention) By the way, when tuning the performance of the booster, the output shaft 07 may need to be extracted from the booster 01 in some cases. However, in the brake booster 01 configured as described above, the output shaft 07 cannot be simply pulled out because the retainer 010 prevents the output shaft 07 from coming off. In order to extract the output shaft 07, both shells 05 and 06 must be disassembled. For this reason, there is a problem that a predetermined operation such as performance tuning becomes extremely troublesome.

The present invention has been made in view of such a problem, and its purpose is to reliably prevent the output shaft from falling off, and to perform a predetermined operation such as performance tuning.
An object of the present invention is to provide a negative pressure booster which can be easily performed without disassembling a shell.

Means for Solving the Problems To solve the above-mentioned problems, the invention of claim 1 is that the retainer engages with the output shaft in the movement of the output shaft in the direction opposite to the inoperative position direction. And a locking portion for releasing engagement with the output shaft when a force of a predetermined magnitude is applied to the output shaft against a biasing force of the retainer toward the inoperative position. It is characterized by having.

In the invention of claim 2, a step is formed at the rear end of the output shaft such that the rear end side has a large diameter portion, the retainer is formed in a cylindrical shape, and the locking portion is ,
The output shaft and the retainer are formed on the inner peripheral surface of the retainer, and are elastically deformed when a force of a predetermined magnitude is applied to the output shaft against a biasing force of the retainer toward the inoperative position. It is a projection for releasing engagement with.

(Operation) In the negative pressure booster of the present invention having such a configuration, when the output shaft moves in the direction opposite to the non-operation position direction, the output shaft engages with the retaining portion of the retainer. Therefore, the output shaft is reliably prevented from falling off by the retaining portion of the retainer.

Further, when a force of a predetermined magnitude is applied to the output shaft against the urging force of the retainer toward the inoperative position, the engagement between the output shaft and the locking portion of the retainer is released, The output shaft can be easily extracted from the vacuum booster. Thus, the output shaft can be easily extracted without disassembling the negative pressure booster and in the assembled state.

The retainer is formed in a cylindrical shape, and the retaining portion is formed on the inner peripheral surface of the cylindrical shape by a projection which is elastically deformed when a predetermined amount of force is applied, thereby preventing the output shaft from falling off. The structure for is simplified.

(Example) Hereinafter, an example of the present invention is described using a drawing.

The negative pressure booster according to the present invention has substantially the same structure and operation as the conventional general brake booster shown in FIG. 3, so that only the different parts will be described. Is omitted.

FIG. 1 is a partial sectional view similar to FIG. 4, showing an embodiment of the present invention, and FIG. 2 is a view seen from a direction A.

As shown in FIGS. 1 and 2, the retainer 1 is formed in a cylindrical shape by an elastic member, and has an output shaft 2 inside thereof.
The rear end large diameter portion 2a is fitted. A flange 1 a is formed at the rear end of the retainer 1, and the flange 1 a supports the rear end of the return spring 3.
The inner peripheral surface of the retainer 1 has three mountain-shaped protrusions 1b, 1b.
b and 1b are formed at equal intervals in the circumferential direction. The protrusion 1b
May be provided in an appropriate number other than three, and the shape may be other than the mountain shape.

The rear inclined surface 1c of the projection 1b is located at the rear end large diameter portion 2a
Are engaged with the step 2b. That is, output shaft 2
Is engaged with the projection 1b of the retainer in a direction opposite to the direction in which the elastic force of the return spring 3 urges the retainer 1 toward the non-operation position. The protrusion 1b is formed so as to be elastically deformable. In this case, the protrusion 1b is hardly elastically deformed when receiving the elastic force of the return spring 3 and pressing the output shaft 2 toward the inoperative position (that is, backward). Step
2b, but when a predetermined amount of force is applied to the output shaft 2 against the pressing force toward the inoperative position, the output shaft 2 is elastically deformed and engages with the step portion 2b. Is set to cancel. That is, the projection 1b constitutes the locking portion of the present invention.

According to the retainer configured as described above, the output shaft 2 is normally pressed by the elastic force of the return spring 3 toward the inoperative position. Further, in order to tune the performance of the brake booster, when the output shaft 2 is pulled forward against the rearward pressing force of the retainer 1 by a predetermined size, the stepped portion 2b becomes inclined 1c of the projection 1b. Press the projection
1b is elastically deformed to increase its inner diameter, thereby releasing the engagement with the step portion 2b. For this reason, the output shaft 2 can be easily extracted from the brake booster. Further, in order to assemble the output shaft 2 with the brake booster, after the rear end of the rear end large diameter portion 1a is brought into contact with the front inclined surface 1d of the projection 1b,
When the output shaft 2 is further pressed rearward, the projection 1b is elastically deformed, and the large-diameter portion 1a at the rear end rides over the projection 1b and is located rearward as shown in FIG. In this position, the output shaft 2 is prevented from dropping because the step 2b is engaged with the inclined surface 1c of the projection 1b as described above.

Thus, in the negative pressure booster of the present embodiment, the output shaft 2 can be easily attached and detached in the assembled assembly state without disassembling the negative pressure booster. Therefore, predetermined operations such as tuning of the performance of the negative pressure booster are extremely simple and efficient. In particular, in the non-disassembly type vacuum booster, it is necessary to break the shell in order to extract the output shaft 2, but according to the vacuum booster of the present embodiment, without breaking the shell, The output shaft can be attached and detached.

Note that the present invention is not limited to the above-described embodiment, and can be applied to other boosters such as a clutch booster other than the brake booster.

In the above-described embodiment, the return spring 3 urges the power piston via the retainer 1 and the output shaft 2, but in the present invention, the return spring 3 attaches the power piston only via the retainer 1. Needless to say, the present invention can also be applied to a negative pressure booster of an energizing type.

(Effects of the Invention) As is apparent from the above description, according to the negative pressure booster of the present invention, the retaining portion of the retainer is engaged with the output shaft, so that the output shaft is securely prevented from falling off by the retainer. can do.

Also, by applying a predetermined amount of force to the output shaft against the urging force of the retainer toward the inoperative position, the output shaft can be easily extracted from the vacuum booster. Thus, the output shaft can be easily extracted without disassembling the negative pressure booster and in the assembled state. Therefore, a predetermined operation such as performance tuning in the negative pressure booster becomes extremely simple and efficient. In particular, in a non-disassembled type vacuum booster, it is necessary to break the shell in order to extract the output shaft, but according to the vacuum booster of the present invention, the shell of the output shaft is not broken without breaking the shell. Desorption can be performed.

Further, the retainer is formed in a cylindrical shape, and a projection for elastically deforming when a predetermined magnitude of force is applied is formed on an inner peripheral surface of the cylindrical shape, so that a structure for preventing the output shaft from falling off is provided. It's easy.

[Brief description of the drawings]

FIG. 1 is a sectional view of a rear end portion of an output shaft of an embodiment of a negative pressure booster according to the present invention, FIG. 2 is a view seen from a direction A in FIG. 1, and FIG. FIG. 4 is a schematic view showing a brake booster as a negative pressure booster, and FIG. 4 is a partial sectional view corresponding to FIG. 1 of the conventional negative pressure booster. DESCRIPTION OF SYMBOLS 1 ... Retainer, 1a ... Flange part, 1b ... Protrusion, 1c, 1d ... Inclined surface, 2 ... Output shaft, 2a ... Rear end large diameter part, 2b ... Step part, 3 ...
Return spring

Claims (2)

(57) [Scope of request for utility model registration] 1. A pressure difference is generated by operating an input shaft and switching a control valve between a constant pressure chamber and a variable pressure chamber defined by a power piston in a space formed by a front shell and a rear shell; The power piston is actuated by the pressure difference to output the front shell through an output shaft that air-tightly penetrates with a sealing means, and the power piston is always in a non-operating position via a retainer due to the elasticity of a return spring. Wherein the retainer is engaged with the output shaft during movement of the output shaft in a direction opposite to the inoperative position direction, and the output shaft is A locking portion for releasing engagement with the output shaft when a force of a predetermined magnitude is applied against a biasing force of the retainer toward the inoperative position. Negative pressure booster characterized by the following. 2. A rear end portion of the output shaft is formed with a step having a large diameter portion on a rear end side, and the retainer is formed in a cylindrical shape. The retainer is formed on an inner peripheral surface, and is elastically deformed when a force of a predetermined magnitude is applied to the output shaft against a biasing force of the retainer toward the inoperative position. The negative pressure booster according to claim 1, wherein the projection is a projection for releasing the engagement.