JP2623741B2 - Brake booster - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake booster, and more particularly to a brake booster including a plurality of sets of constant pressure chambers and variable pressure chambers in a shell, such as a tandem brake booster. Related to power devices.

2. Description of the Related Art Conventionally, as a brake booster, a center plate that partitions the inside of a shell into a plurality of chambers, a valve body having a substantially circular cross section slidably penetrating the center plate, A power piston provided in each chamber partitioned by the valve body and connected to the valve body, a diaphragm stretched on the back of each power piston to partition each chamber into a constant pressure chamber and a variable pressure chamber,
A constant pressure passage formed in the valve body and communicating between the constant pressure chambers, a variable pressure passage formed in the valve body and communicating between the variable pressure chambers, and a valve plunger connected to an input shaft; A valve mechanism for switching the communication state between the constant pressure passage, the variable pressure passage and the pressure passage for supplying the pressure fluid in accordance with the advance and retreat, and a push rod interposed between the end face of the valve plunger and the base end face of the push rod. There is known a brake booster including a reaction disk for transmitting an applied brake reaction force to an input shaft (Japanese Patent Application Laid-Open No. 60-154552).

[Problems to be Solved by the Invention] By the way, in the tandem type brake booster having the above configuration, compared with the single type brake booster, there are two sets of the constant pressure chamber and the variable pressure chamber. The volume is increased, and thus the amount of air flowing through the constant pressure passage and the variable pressure passage increases.

To increase the flow path area of the constant pressure passage and the variable pressure passage, the valve body may be increased in size. However, if the valve body is increased, the size of the brake booster is undesirably increased. On the other hand, if the valve body is not enlarged, a sufficient flow passage area cannot be secured in each of the above passages. There is a possibility that the brake will be dragged late.

"Means for Solving the Problems" In view of such circumstances, the present invention has a center plate that partitions the inside of the shell into a plurality of chambers, and a substantially circular cross section penetrating the center plate slidably. A valve body, a power piston provided in each chamber partitioned by the center plate and connected to the valve body, and a diaphragm stretched on the back of each power piston to partition each chamber into a constant pressure chamber and a variable pressure chamber. When,
A constant pressure passage formed in the valve body and communicating between the constant pressure chambers, a variable pressure passage formed in the valve body and communicating between the variable pressure chambers, and a valve plunger connected to an input shaft; A valve mechanism for switching a communication state between the constant-pressure passage, the variable-pressure passage and the pressure passage for supplying the pressure fluid in accordance with the forward and backward movements, and a brake mechanism housed in a recess formed in a base of the push rod and applied to the push rod. A brake booster having a reaction disk for transmitting a force to the valve plunger, wherein the cross-sectional shape of the outer peripheral surface of the base of the push rod is formed from a circular shape to a non-circular shape with a part cut away from the circular shape; At least one of the constant pressure passage and the variable pressure passage is formed in the notch.

[Operation] As described above, if the cross-sectional shape of the outer peripheral surface of the base of the push rod is formed in a non-circular shape with respect to the valve body having a substantially circular cross-section, the valve body is relatively formed with respect to the portion where the notch is formed. A large margin can be ensured, so that a relatively large passage can be formed there while ensuring the strength of the valve body.

"Example" Hereinafter, an example in which the present invention is applied to a triple type brake booster will be described.
The shell 1 comprises a stepped cup-shaped front shell 2 and a substantially dish-shaped rear shell 3 for sealing the opening of the front shell 2. A front side center plate 4 formed in a stepped cup shape is fitted into the inside of the front shell 2 so as to follow the inner surface thereof, and an end wall surface of the front side center plate 4 and an end portion of the front shell 2 are fitted. A front room 5 is formed between the wall and the wall.

A cup-shaped rear center plate 6 is fitted into the inside of the stepped cup-shaped front center plate 4, and an end wall surface of the rear center plate 6 and a front center plate are fitted. A center chamber 7 is defined between the end wall of the rear shell 4 and a rear chamber 8 between the end wall of the rear center plate 6 and the wall of the rear shell 3.

A through hole is formed in each of the central shaft portions of the front side center plate 4, the rear side center plate 6, and the rear shell 3, and a valve body 9 having a substantially circular cross section slides in each through hole. Each center plate 4, 6 and rear shell 3
Airtightness is maintained between the valve body 9 and the valve body 9 by a seal member 10.

Further, a front power piston 14, a center power piston 15 and a rear power piston 16 are disposed in the front chamber 5, the center chamber 7 and the rear chamber 8, respectively, and the power pistons 14 to 16 are mounted on the valve body 9 respectively. In addition, a front diaphragm 17, a center diaphragm 18, and a rear diaphragm 19 are provided on the rear side surfaces of the power pistons 14 to 16, respectively.

The front chamber 17 is divided into a front-side constant-pressure chamber A and a rear-side variable-pressure chamber B by the front diaphragm 17, and the center chamber 7 is similarly divided into a constant-pressure chamber C and a variable-pressure chamber D by the center diaphragm 18. Further, the rear chamber 8 is divided into a constant pressure chamber E and a variable pressure chamber F by a rear diaphragm 19.

However, a conventionally known valve mechanism 23 is housed in the valve body 9. The valve mechanism 23 includes an annular first valve seat 24 formed in the valve body 9 and an annular first valve seat 24.
An annular second valve seat 26 formed at the right end of a valve plunger 25 slidably provided on the valve body 9 inside the valve seat 24.
And a valve element 28 which is seated on both valve seats 24 and 26 from the right side in FIG.

A space outside the annular seat portion where the first valve seat 24 and the valve element 28 are in contact with each other is communicated with the inside of the constant pressure chamber A of the front chamber 5 through an axial constant pressure passage 31 formed in the valve body 9. The constant pressure chamber A is connected to a negative pressure source such as an intake manifold (not shown) via a negative pressure introducing pipe 32 attached to the front shell 2. The constant-pressure passage 31 and the constant-pressure chamber C of the center chamber 7 are provided in the valve body 9.
A constant-pressure passage 33 in the radial direction that communicates with
Constant-pressure passage communicating with the pressure chamber E of the rear chamber 8
34 are formed, and the negative pressure introduced into the constant pressure chamber A is constantly applied to the respective constant pressure chambers C, C through the respective constant pressure passages 31, 33, 34.
E can be introduced inside.

In addition, a portion on the inner peripheral side of the annular seat portion where the first valve seat 24 and the valve element 28 contact, and an outer peripheral side of the annular seat portion where the second valve seat 26 and the valve element 28 contact, The space in the intermediate portion of the annular seat portion communicates with the inside of the variable pressure chamber F of the rear chamber 8 through a variable pressure variable passage 38 formed in the valve body 9 in the radial direction. The variable pressure chamber F is formed through the first variable pressure passage 39 formed in the valve body 9.
And is communicated with the inside of the transformation chamber B of the front chamber 7 via a second transformation passage 40 formed in the valve body 9 independently of the first transformation passage 39.

On the other hand, the space on the inner peripheral side of the annular seat portion where the second valve seat 26 and the valve element 28 are in contact with each other is communicated with the atmosphere via the axial pressure passage 41 and the filter 42.

Further, a right end of the valve plunger 25 slidably provided on the valve body 9 is connected to an input shaft 45 linked to a brake pedal (not shown), and a left end thereof is formed on a base 46a of the push rod 46. It faces the right end surface of the reaction disk 47 housed in the recessed portion. The left end of the push rod 46 is slidably protruded from the shaft of the front shell 1 to the outside via a sealing member 48, and is linked to a piston of a master cylinder (not shown). The valve body 9 and the like are normally held at a non-operating position in the figure by a return spring 49.

In the above configuration, in a non-operating state in which the brake pedal is not depressed, the valve body 28 is seated on the second valve seat 26 provided on the valve plunger 25 to close the pressure passage 41 communicating with the atmosphere. Since the valve body 28 is separated from the first valve seat 24, the constant pressure passage 31 which is always in communication with the constant pressure chambers A, C and E is connected to the variable pressure passage 38 which communicates with the variable pressure chambers B, D and F. A negative pressure is introduced into all the chambers A to F in communication.

When the brake pedal is depressed from this state and the input shaft 45 moves leftward, the valve body 28 is seated on the first valve seat 24 and the valve body 28 and the second valve seat 42 are separated from each other. Passage 31
The communication between the constant-pressure chambers A, C, and E and each of the variable-pressure chambers B, D, and F is cut off, and the air is introduced into each of the variable-pressure chambers B, D, and F. You.

Thereby, each of the constant pressure chambers A, C, E and each of the variable pressure chambers B, D, F
When a pressure difference is generated between the power cylinders, the power pistons 14 to 16 and the valve body 9 and the like are integrally moved to the left to advance the push rod 27 and generate a brake fluid pressure in a master cylinder (not shown) to operate the brake. Let them do it.

When the brake pedal is released from the brake operation state, the flow path of the valve mechanism 23 is switched to cut off the communication between the variable pressure chambers B, D, and F and the atmosphere, and the variable pressure chambers B, D, F Is communicated with the constant pressure chambers A, C, and E, so that the atmosphere in each of the variable pressure chambers B, D, and F escapes to a negative pressure source (not shown) through the constant pressure chamber A. And each transformer room B, D,
When the pressure in F decreases, each of the power pistons 14 to 16 is returned to the original inoperative position by the return spring 49.

However, in this embodiment, as shown in FIG.
Push rod containing the above reaction disk 47
The cross-sectional shape of the base 46a of 46 is formed from a circular shape by cutting out both sides thereof into a roughly oval cross-section, and
The shape of the reaction disk 47 housed in the base
It is formed in a roughly oval shape following the shape of 46a. Also,
The end face of the valve body 9 which is in contact with the right end face of the reaction disc 47 is also formed in accordance with the shape of the reaction disc 47, and the portion is protruded toward the front side, and the protruding portion 9a is inserted into the recess of the base 46a. It is slidably fitted.

Two axial constant pressure passages 31 formed in the valve body 9 are formed at both ends in the major axis X direction of the non-circular cross-section of the reaction disc 47, while the first constant pressure passage 39 in the axial direction is formed. And the second variable pressure passage 40, the long axis X
Are formed at both ends in the short axis Y direction intersecting with the notches, that is, at each of the notches formed by the above notches.

Thus, the reaction disk 47 and the push rod 46 are provided for the valve body 9 having a substantially circular cross section.
If the cross-sectional shape of the base portion 46a is formed in a non-circular shape, a relatively large margin can be secured in each of the notched portions of the non-circular cross-section, so that the strength of the valve body 9 is secured. Thus, the variable pressure passages 39 and 40 each having a relatively large flow passage area can be formed therein.

As a result, the transformation chambers B and D are passed through the transformation passages 39 and 40.
The air can be quickly supplied or discharged to the inside, and in particular, when the operation of the brake booster is released, the discharge of the pressurized fluid from each of the variable pressure chambers B and D is promptly performed to delay the discharge. Can be prevented from being dragged by the brake.

At this time, in this embodiment, since the respective variable pressure passages 39 and 40 communicating with the above described variable pressure chambers B and D are formed independently of each other, the pressure fluid discharged from each of the variable pressure chambers B and D is mutually connected. To prevent the pressure fluid discharged from the variable pressure chamber D from being carried out smoothly.

In the above embodiment, each of the notches has a variable pressure passage.
Although 39 and 40 are respectively formed, a constant pressure passage may be formed at both ends thereof, or a constant pressure passage and a variable pressure passage may be formed. Further, it goes without saying that the present invention can be applied to a conventionally known tandem brake booster.

[Effects of the Invention] As described above, according to the present invention, it is possible to secure a large flow passage area as compared with the related art, and to improve the responsiveness of the brake booster, which is favorable for the driver. The effect that a good brake feeling can be provided is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG.
It is sectional drawing which follows the II-II line | wire of a figure. 1, shell 4, 6, center plate 5, 7, 8 chamber 9, valve body 14, 15, 16 power piston 17, 18, 19 diaphragm 23 valve mechanism 25 ... Valve plunger 31 ... Constant pressure passage, 39, 40 ... Variable pressure passage 41 ... Pressure passage, 45 ... Input shaft 46 ... Push rod, 46a ... Base 47 ... Reaction discs A, C, E ... Constant pressure Room B, D, F ... Transformer room

Claims (1)

(57) [Claims] A center plate for partitioning the inside of a shell into a plurality of chambers, a valve body having a substantially circular cross section slidably penetrating through the center plate, and a chamber provided in each of the chambers partitioned by the center plate. A power piston respectively connected to the valve body, a diaphragm stretched on the back surface of each power piston to partition each chamber into a constant pressure chamber and a variable pressure chamber, and a diaphragm formed in the valve body and between the respective constant pressure chambers. A constant pressure passage communicating therewith, a variable pressure passage formed in the valve body and communicating between the variable pressure chambers, and a valve plunger connected to an input shaft, wherein the constant pressure passage, the variable pressure passage and A valve mechanism for switching a communication state between pressure passages for supplying a pressurized fluid; A brake booster having a reaction disk for transmitting a brake reaction force applied to a rod to the valve plunger, wherein a cross-sectional shape of an outer peripheral surface of a base of the push rod is formed in a non-circular shape in which a part is cut away from a circular shape. Along with
A brake booster characterized in that at least one of the constant pressure passage and the variable pressure passage is formed in the notch.