JPS60226349A - Brake booster servo unit - Google Patents

Abstract

PURPOSE:To omit a seal member and thereby reduce sliding resistance, by setting up both input and output shafts of a servo unit at the outside of a master cylinder in place of the seal member. CONSTITUTION:A master cylinder 2 is interposed between a booster 1 and a car body 3. An input shaft 17 and an output shaft 31 of the booster 1 are set up outside this master cylinder 2. The output shaft 31 is connectedly installed in a piston 39 of the master cylinder via a lever 38 being tightly attached to this shaft 31. Therefore, both input and output shafts 17 and 31 are not installed inside the master cylinder 2 so that a seal member becomes useless, thus sliding resistance is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brake booster, and more particularly to a brake booster in which a master cylinder is disposed on the rear side of a booster mechanism including a power piston, that is, on the brake pedal side. .

In conventional brake boosters commonly used, a master cylinder is connected to the front side of the booster mechanism, and the shell of the booster mechanism is attached to the vehicle body. Since the shell is required to have enough rigidity to support the master cylinder, there is a certain limit to the weight reduction of the brake booster by reducing the thickness of the shell.

On the other hand, in a brake booster in which a master cylinder is arranged at the rear of the external force mechanism, the master cylinder can be attached to the vehicle body, so the shell simply has enough rigidity to withstand fluid pressure. It is sufficient to have
It is advantageous for reducing the weight of the brake booster. However, since the positions of the booster mechanism and the master cylinder are reversed from the normal arrangement, conventionally the input shaft and the output shaft have been provided so as to be able to slide freely through the inside of the master cylinder.

However, if the output shaft is made to pass through the shaft of the master cylinder, a sealing member is required for this purpose, which increases sliding resistance, and the master cylinder also has a special configuration. Therefore, there was a drawback that the cost was high.

In view of such circumstances, the present invention provides a brake booster in which a master cylinder is disposed on the rear side of the booster mechanism.
- By arranging the input shaft and output shaft outside the master cylinder, the sealing member required when they pass through the master cylinder is omitted, reducing sliding resistance, and at the same time, it is possible to reduce the sliding resistance compared to the conventional general configuration. The present invention provides a brake booster that can use a master cylinder.

The present invention will be described below with reference to the illustrated embodiment. In the figure, a shell 1 consists of a front shell la and a palm lb, with a master cylinder 2 connected to the palm lb. This master cylinder 2 includes a cylindrical main body part 2a, a tip part 2b and a base part 2 which are integrally formed eccentrically in the same direction from both end shaft parts of this main body part 2a.
C, and its tip 2b is connected to the rear shell 1b.
The base 2C is fixed to the vehicle body 3.

A valve body 5 integrally equipped with a power piston 4 is provided inside the shell l so as to be able to reciprocate along the axial direction of the shell l. The interior is divided into a constant pressure chamber 7 on the front shell la side and a variable pressure chamber 8 on the rear shell lb side.

The valve body 5 is generally formed into a cylindrical shape as a whole, and a seal member 10 is provided between its tip and an opening 9 formed in the shaft of the front shell 1a, and the valve body 5 is connected to the front shell 1a. Normally, it is held in the non-operating position shown in the drawings by a return spring 11 loaded between the main body and the main body.

Inside the L pulp body 5 is a valve mechanism 1 for switching the fluid circuit.
5, and this valve mechanism 15 includes an annular first valve seat 16 formed on the inner peripheral surface of the valve body 5, and this first valve seat 1.
6 and a second valve seat 18 formed at the tip of the input shaft 17, and a valve body 19 seated on each valve seat 16 and 18 from the front side in the operating direction of the power piston 4, that is, from the left side in the figure. . In the illustrated non-operating state, the valve body 18 includes a closing member 20 that closes the shaft hole of the valve body 5 and the valve body 1 .
8, the second valve seat 18 of the input shaft 17 is seated on the first valve seat 16 by a spring 21 loaded between the input shaft 17 and the closing member 2.
0 and the input shaft 17, the first
It is separated from the valve body 19 seated on the valve seat 16.

The base of the valve body 18 is connected to the closing member 20, and outside the seat portion between the valve body 19 and the first valve seat 16 are a plurality of axial passages 23 and a filter 24 formed in the closing member 20. It communicates with the atmosphere through. On the other hand, inside the seat portion of the valve body 19 and the second valve seat 18, a plurality of radial passages 25 and a valve are formed in the closing member 20 so as not to communicate with the axial passage 23 of the closing member 20. It communicates with the constant pressure chamber 7 via a passage 26 formed in the body 5. Furthermore, a support member 2 that forms part of the valve body 5 is located between the seat portion between the valve body 18 and the first valve seat 16 and the seat portion between the valve body 18 and the second valve seat 18.
It communicates with the variable pressure chamber 8 through a through hole 28 formed in 7.

The input shaft 17 is composed of three members, namely, a first input shaft 17a, a second manpower shaft 17b, and a third manpower shaft 17c, and the second valve seat 18 is attached to the tip of the first input shaft 17a. is forming. Then, the second human power shaft 17b to which the first input shaft lea is screwed is connected to the tip end 2b of the master cylinder 2.
and the base portion 2c, and the tip spherical portion 17d of the third human shaft 17c is inserted through the connecting member 29 to the distal end thereof.
Further, the distal end of the first input shaft 17a is linked to a brake pedal (not shown).

A fitting device is provided on the outer periphery of the second human power shaft 17b to allow the output shaft 31 to slide freely. A reaction disk 33 is disposed on the back surface of the nut member 32 so that the thrust applied to the power piston 4, valve body 5, and support member 27 can be received through the reaction disk 33 and the nut member 32. That's what I do.

The nut member 32 and the reaction disk 33 are slidably housed in a recess formed in the support member 27, and the support member 27 has a ring member 34 on the back side of the action disk 33. It is installed so that it can slide freely. And the second human power axis 1 mentioned above? A protrusion 35 formed at the tip of b is slidably passed through a slit 36 formed in the output shaft 31 and positioned on the back surface of the ring member 34,
The reaction force from the reaction disc 33 can be transmitted to the brake pedal via the ring member 34 and the projection 35, and further via the input shaft 17.

The output shaft 31 slidably passes through the tip 2b and the base 2c of the master cylinder 2, and the tip of the lever 38, which is fixed with a nut 37 at a position forward of the base 2C of the master cylinder 2, is inserted into the master cylinder 2. It is brought into contact with the end of a piston 39 that is slidably fitted into the main body 2a of the main body 2a. In the illustrated embodiment, the master cylinder 2 is constructed as a two-system master cylinder 7, and since such a two-system master cylinder is well known in the art, a detailed explanation of its structure will be omitted.

In the above configuration, in the illustrated non-operating state, the power piston 4 and the pulp body 5 are held at the illustrated positions by the return spring 11, the input shaft 17 is urged rightward together with the output shaft 31 by the spring 22, and the reaction disk 33 is stopped in a lightly compressed state. In this state, the valve body 18 is seated on the first valve seat 16 and the variable pressure chamber 8
At the same time, the valve body 18 and the second valve seat 18 are separated from each other to establish communication between the variable pressure chamber 8 and the constant pressure chamber 7. Therefore, the negative pressure introduced into the constant pressure chamber 7 from the negative pressure inlet (not shown) provided in the front shell 1a is
It is introduced into the variable pressure chamber 8 through the passage 26, 25, the gap between the valve body 19 and the second valve seat 18, and the through hole 28, so that no pressure difference occurs before and after the power piston 4.

From this state, when the brake pedal (not shown) is depressed and the input shaft 17 is moved to the left, the second valve seat 18 first moves against the valve body 18.
The valve body 18 is seated on the first valve seat 1B to cut off the communication between the constant pressure chamber 7 and the variable pressure chamber 8, and then the input shaft 17 is moved leftward to remove the valve body 18 from the first valve seat IB. Then, the atmosphere enters the filter 24, the passage 23, the gap between the valve body 19 and the first valve seat 16, and the through hole 2.
8 into the variable pressure chamber 8 to create a pressure difference across the power piston 4 and the pulp body 5, causing them to move to the left against the return spring 11.

When the pulp body 5 moves to the left, its thrust is transmitted to the piston 39 of the master cylinder 2 via the reaction disc 33, nut member 32, output shaft 31, and lever 38, thereby increasing brake fluid pressure in the master cylinder 2. When the brake fluid pressure is generated, as is well known in the art, the brake fluid pressure is supplied to a wheel cylinder (not shown) to perform a braking action. During this time, as mentioned above, the brake reaction force is transferred from the reaction disc 33 to the ring member 34.
, is transmitted to the brake pedal via the protrusion 35 and the input shaft 17.

If you release the pressure on the brake pedal from the above braking state,
Since the valve mechanism 15 is switched to the illustrated state, it is clear that the valve mechanism 15 returns to the above-mentioned non-operating state.

In the above embodiment, the output shaft 31 is fitted around the outer periphery of the input shaft 17, but it is of course possible to arrange the output shaft 31 in the opposite manner.

As described above, the present invention is a brake booster in which the master cylinder is disposed on the rear side of the booster mechanism, in which the input shaft and the output shaft are disposed outside the master cylinder. There is no need to provide a sealing member to prevent brake fluid pressure from leaking between the input shaft or output shaft and the master cylinder, unlike when the brake fluid is penetrated into the master cylinder. Therefore, by omitting the sealing member, It can reduce sliding resistance and improve operability. Furthermore, since it is possible to use a master cylinder that has substantially the same configuration as a conventional general master cylinder, it is possible to share one part and manufacture it at a low cost. .

[Brief explanation of drawings]

The figure is a partial sectional view showing one embodiment of the present invention. l...Shell 1a...Front shell 1b...
Rear shell 2... Master cylinder 2a... Main body 2b... Tip 2C... Base 4... Power piston 5... Valve body 15... Valve mechanism 17... Input shaft 31.
...Output shaft 38...Lever 38...Piston procedure amendment form (0
Illusion 1. Display of the case 1982 Patent Application No. 82615 2, Name of the invention Brake booster 3, Person making the amendment Relationship to the case Patent applicant address 2-10-12 Yoyogi, Shibuya-ku, Tokyo Name Automobile Equipment Co., Ltd. 4. Agent 5, detailed description of the invention in the specification subject to amendment, and drawings. 6. Details of correction (1) "Slit 3B" on page 7, lines 6-7 of the specification is corrected to "slit 36." (2) Amend the drawing as shown in the attached sheet.

Claims (1)

[Claims] A power piston is slidably provided in a shell having a front shell and a palm shell, a valve mechanism housed in a pulp body of the power piston shaft, and a master cylinder connected to the palm cylinder located on the brake pedal side. , an input shaft disposed outside the master cylinder to interlock the E valve distribution mechanism and the brake pedal, and an output shaft disposed outside the master cylinder to interlock the power piston and the piston of the master cylinder. A brake booster comprising: