JP2798806B2 - Brake booster - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a brake booster for reducing the operation force of a brake pedal.

"Conventional technology" As a brake booster for reducing the operation force of the brake pedal, a brake shell is provided on the front shell that is provided on the master cylinder side that generates brake hydraulic pressure and on the operating rod that receives input from the brake pedal. A casing having a rear shell provided therein, a constant pressure chamber in the casing communicating with a negative pressure source, and a vacuum passage having a vacuum valve, and communicating with the negative pressure source through an atmosphere passage having an atmosphere valve. And a working pressure chamber in the casing that communicates with the atmosphere, and separates the constant pressure chamber and the working pressure chamber, and drives the output shaft by moving according to a pressure difference between the constant pressure chamber and the working pressure chamber. And a return spring that urges the power piston toward the working pressure chamber.

As a conventional brake booster with such a structure,
For example, those disclosed in Japanese Patent Application Laid-Open No. 1-127446 can be mentioned. In this brake booster, a bellows is provided and partitioned in a constant-pressure chamber to connect a negative pressure source and a vacuum valve, and one is used as a constant-pressure chamber and the other is connected to the negative pressure source and a vacuum valve. Used as a vacuum passage.

"Problem to be Solved by the Invention" However, in the above-described structure, there is a problem that the partition portion is easily deformed by a pressure change because the partition portion is a bellows. In addition, the bellows may be caught in the operating portion by this deformation and may be damaged. Therefore, it is conceivable to provide a guide instead of the bellows, but the structure becomes complicated and the weight increases. It is also conceivable to use a material having a certain degree of hardness as the bellows. However, the bellows may become a resistance when the power piston is operated, and may not be constantly used and may be torn.

Therefore, an object of the present invention is to provide a brake booster having a simple structure and light weight without using a bellows.

Means for Solving the Problems In order to achieve the above object, a brake booster of the present invention is provided with an operating system which receives inputs from a front shell and a brake pedal arranged on a master cylinder side for generating a brake hydraulic pressure. A casing having a rear shell disposed on the rod side, a constant pressure chamber in the casing communicating with a negative pressure source, and an atmosphere valve communicating with the negative pressure source via a vacuum passage having a vacuum valve. A working pressure chamber in the casing that communicates with the atmosphere via an atmosphere passage, and partitions the working chamber between the constant pressure chamber and the working pressure chamber while moving according to a pressure difference between the constant pressure chamber and the working pressure chamber. A brake booster having a power piston that drives an output shaft and a return spring that urges the power piston toward the working pressure chamber. The air passage is
A passage pipe communicating with the negative pressure source, airtightly fixed to the front shell, and extending in a rear shell direction so as to cover the output shaft; and a recess formed around the output shaft of the power piston. A seal member fixed to the opening of the concave portion, airtightly fitted to the outer periphery of the passage pipe, and slidable on the passage pipe with the movement of the power piston, and provided inside the power piston. , And an internal passage for communicating the recess with the vacuum valve.

According to the present invention, air is moved through a vacuum passage such as flowing air in a working pressure chamber to a negative pressure source, and when the power piston moves with the movement of the air, the vacuum passage is moved. The seal member is formed in a recessed portion of the power piston and hermetically fits with the outer periphery of the passage pipe extending from the front shell to the rear shell. It slides while maintaining the airtightness in the passage.

Embodiment A brake booster according to an embodiment of the present invention will be described below with reference to FIG. In this embodiment, a brake booster that can also perform brake control such as traction control without input from a brake pedal will be described as an example. However, a brake booster that operates only with an input from a brake pedal is described. The device can of course have the same structure. In this embodiment, a tandem type brake booster (having two constant pressure chambers and two working pressure chambers) will be described as an example, but a single type brake booster (a constant pressure chamber and an operating pressure chamber) will be described. Of course, a structure having one pressure chamber may have the same structure. Further, in this embodiment, when there is no input from the brake pedal, the vacuum valve and the atmosphere valve are closed, and both the constant pressure chamber and the working pressure chamber are kept at a negative pressure. A so-called short travel type is described as an example in which the power piston is moved by opening the air to flow into the working pressure chamber to move the power piston. However, a brake booster other than the short travel type can of course have the same structure. .

In the drawing, reference numeral 1 denotes an operating rod that moves in response to an input from a brake pedal (not shown), reference numeral 2 denotes a casing of a brake booster, reference numeral 2a denotes a front shell constituting the casing 2, and reference numeral 2b denotes the same casing 2.
, Reference numeral 3 denotes a bracket forming a part of the front shell 2a, and reference numeral 4 denotes a negative pressure source.

Further, the casing 2 is divided into two parts by a center plate 5 that slidably supports the outer periphery of a valve body described later while maintaining airtightness. Each of the casings 2 is further connected to a negative pressure source 4 by a power piston described later. Constant pressure chamber 6,
A first constant pressure chamber 8 communicating with the second constant pressure chamber 6 via a constant pressure passage 7; and an atmosphere passage 9 communicating with the negative pressure source 4 via a vacuum passage (described later) and having an atmosphere valve (described later). And a first working pressure chamber 11 communicating with the atmosphere via a filter silencer 10 therein, and a second working pressure chamber 13 communicating with the first working pressure chamber 11 via a working pressure passage 12. . The inner periphery of the center plate 5 is provided with a seal / sliding member 14.
Is fixed, and the sealing and sliding member 14 slides on the outer periphery of a valve body (described later).

In addition, as described above, the first constant pressure chamber 8 and the first working pressure chamber 11
And the first constant pressure chamber 8 and the first working pressure chamber.
1st diaphragm plate part 15 which receives pressure difference with the inside 15
A second diaphragm plate portion 16 which partitions between the second constant pressure chamber 6 and the second working pressure chamber 13 and receives a pressure difference between the inside of the second constant pressure chamber 6 and the inside of the second working pressure chamber 13; The power piston 18 is constituted by the valve body 17 to which the plate portions 15 and 16 are fixed. Power piston 18
Since the thrust generated therein drives an output shaft 19 that presses a piston of a master cylinder (not shown), it is formed to be movable in the left-right direction in FIG. Note that the first diaphragm plate portion 15 is composed of a diaphragm plate 15a and a diaphragm 15b, and the second diaphragm plate portion 16 is composed of a diaphragm plate 16a and a diaphragm 16b. The circumferential side is fixed to the valve body 17.
Thus, the second constant pressure chamber 6 and the second working pressure chamber 13 are movable with respect to the casing 2 while maintaining the airtightness. A boot 20 that is deformable with the movement of the valve body 17 is attached between the tip of the valve body 17 and the rear shell 2b.

Then, as the power piston 18 moves, the volumes of the first constant pressure chamber 8, the first working pressure chamber 11, the second constant pressure chamber 6, and the second working pressure chamber 13 change. A return spring 21 for urging the power piston 18 toward the first working pressure chamber 11 is provided in the second constant pressure chamber 6.

Further, the vacuum passage 22 includes a passage tube 23, a concave portion 24, and a seal member.
25 and an internal passage 26. First, the negative pressure source 4 communicates with the inlet 27 of the bracket 3, passes through the inside of the bracket 3, and is connected to the passage pipe 23. Here, passage pipe 23
Is airtightly fixed to the approximate center of the bracket 3 and the output shaft 19
And the rear shell 2b so as to cover the
Direction. Further, the concave portion 24 is formed by the periphery of the output shaft 19 and the inner periphery of a spring seat 28 provided inside the valve body 17 of the power piston 18 in an airtight manner. A seal member 25 is fixed to the opening 29 of the concave portion 24. The seal member 25 slides on the passage tube 23 by moving the power piston 18 while airtightly fitting with the outer periphery of the passage tube 23. It has become. The internal passage 26 is provided with the power piston 18
The recess 24 communicates with a vacuum valve described later.

An atmospheric valve 31 and a vacuum valve 32 are provided in the small-diameter cylindrical portion 30 of the valve body 17 of the power piston 18. The atmospheric valve 31 is operated by the operating rod 1 and is opened by a relative advance (movement to the left in FIG. 1) of the operating rod 1 to regulate the introduction of the atmosphere into the first working pressure chamber 8. Things. Here, the atmosphere valve 31 includes a seat surface 33a at the tip of a poppet 33 and an annular convex portion 34a of a valve plunger 34. When an input is made from a brake pedal (not shown), the operating rod 1 is used. The valve plunger 34 is pressed and opened. The operating rod 1 is a spring
It is always urged to the right by 1a etc. The reaction disk 35 is provided between the output shaft 19 and the valve body 17 and transmits a reaction force from the output shaft 19 to the operating rod 1 via the valve plunger 34.

The vacuum valve 32 provided at the boundary of the vacuum passage 22 with the first working pressure chamber 11 is opened by the relative retreat of the operating rod 1 (moving rightward in FIG. 1), and the first working pressure The communication between the chamber 11 and the negative pressure source 4 is regulated.
Here, the vacuum valve 32 is constituted by the convex portion 18a of the power piston 18 and the seat surface 33a at the tip of the poppet 33, so that the first constant pressure chamber can be operated without operation from a brake pedal (not shown). 8 and the second constant pressure chamber 6 and the first working pressure chamber 11
When the pressure balance between the inside and the second working pressure chamber 13 is lost, the power piston 18 moves toward the second constant pressure chamber 6 (to the left in FIG. 1) and is thereby opened. Further, the vacuum valve 32 is closed when the pressures in the first working pressure chamber 11 and the second working pressure chamber 13 and the pressures in the first constant pressure chamber 11 and the second constant pressure chamber 13 are balanced. (First
State shown in the figure).

The above-described valve plunger 34 balances the power piston 18 in a state where the first constant pressure chamber 8 and the second constant pressure chamber 6 are set to a negative pressure by the negative pressure source 4 to provide the atmosphere valve 31 and the vacuum valve.
A short label mechanism 36 for keeping the valve 32 in a closed state comprises a short travel mechanism 36, a valve plunger 34, a key 37 slidably mounted in the valve plunger 34 in a slightly axial direction, and a key 37 37 is the valve body 17
A groove 38 provided in the valve body 17 so that the key 37 can move in the axial direction, and a stopper plate 39 for stopping the rightward movement of the key 37 in FIG.

Further, in this embodiment, in order to perform brake control such as traction control, communication between the negative pressure source 4 and the vacuum valve 32 is provided in a portion of the vacuum passage 22 between the negative pressure source 4 and the vacuum valve 32. A switching valve 40 for shutting off and introducing the atmosphere to the vacuum valve 32 is provided, and the switching valve 40 is provided with a controller 41 for controlling the operation thereof. Further, a bypass 42 branching from the vacuum passage 22 and communicating with the first working pressure chamber 11 is provided between the switching valve 40 and the first working pressure chamber 11. A check valve 43 is provided which is forward from the side toward the first working pressure chamber 11 and allows only the movement of air in the forward direction.

The operation of the brake booster having such a structure when the brake control is performed by traction control or the like without depending on the input from the brake pedal will be described below.

In the brake booster having the above-described structure, the switching valve 40 connects the negative pressure source 4 to the vacuum valve 32 in a state of waiting for an input from a brake pedal and brake control by traction control or the like. , The inside of the vacuum passage 22, the inside of the first constant pressure chamber 8, and the inside of the second constant pressure chamber 6.
Inside, the inside of the first working pressure chamber 11 and the inside of the second working pressure chamber 13 are all maintained at a negative pressure. The atmosphere valve 31 and the vacuum valve 32 are closed.

Here, when it becomes necessary to generate the brake oil pressure due to traction control or the like, the switching valve 40 is switched by a signal from the controller 41 to switch the negative pressure source 4
A portion from the switching valve 40 to the vacuum valve 32 of the vacuum passage 22 that has been in communication with the air passage is communicated with the atmosphere 44. Then, since the vacuum valve 32 is closed, the air flows into the first working pressure chamber 11 of negative pressure via the bypass 42 and further flows into the second working pressure chamber 13 via the working pressure passage 12. . Then, the balance between the pressures in the first working pressure chamber 11 and the second working pressure chamber 13 and the negative pressures in the first constant pressure chamber 8 and the second constant pressure chamber 6 is lost, and the power piston 18 is moved. The second constant pressure chamber 6 side (left direction in FIG. 1)
And the vacuum valve 32 is opened. At this time, the power piston 18 moves while sealingly fitting the seal member 25 fixed to the opening 29 of the concave portion 24 with the outer periphery of the passage tube 23, so that the atmosphere from the switching valve 40 There is no loss of airtightness in the vacuum passage 22 such as leakage into the chamber 6. Therefore, air flows into the first working pressure chamber 11 and the second working pressure chamber 13 through both the vacuum passage 22 and the bypass 42, and the power piston 18 further moves toward the second constant pressure chamber 6 to output power. Axis 19
, And the tip of the output shaft 19 presses a piston of a master cylinder (not shown) to generate a brake hydraulic pressure.

Next, when the brake control such as the traction control is completed, the switching valve 40 is switched by the signal of the controller 41, and the vacuum valve 32, which has been in communication with the atmosphere 44, is in communication with the negative pressure source 4. Then, since the vacuum valve 32 is open, the air in the first working pressure chamber 11 and the air in the second working pressure chamber 13 are subjected to negative pressure through the internal passage 26, the concave portion 24, Spills to source 4. At this time, the power piston 18 is attached to the seal member 25 fixed to the opening 29 of the recess 24.
Is moved while being fitted airtightly to the outer periphery of the passage tube 23, so that the airtightness in the vacuum passage 22 is not impaired in the same manner as described above. When the pressures in the first working pressure chamber 11 and the second working pressure chamber 13 and the pressures in the first constant pressure chamber 8 and the second constant pressure chamber 6 are balanced, the power piston 18 is moved to the first working pressure chamber 11. Side (to the right in FIG. 1) to close the vacuum valve 32. At this time, the first working pressure chamber 11 is connected to the bypass 42 from the switching valve 40 side.
Since the check valve 43 that allows the movement of the air only to the side is provided, the air does not flow from the first working pressure chamber 11 to the bypass 42. The vacuum passage 22, the first constant pressure chamber 8, the second constant pressure chamber 6, the first working pressure chamber 11, and the second working pressure chamber 13 are all maintained at a negative pressure, and the atmosphere valve 30 and the vacuum With the valve 31 closed, the brake control by the next traction control or the like or the input from the brake pedal waits.

In the above description, the communication between the negative pressure source and the switching valve can of course be indirectly connected to the negative pressure source via, for example, a constant pressure chamber or the like.

Further, regarding the brake booster in the present embodiment,
Although the operation at the time of brake control such as traction control has been described as an example, the operation by the input of the brake pedal and the like are the same as those of the conventional short travel type except that the air flow through the vacuum valve is performed using the vacuum passage having the above configuration. Same as the brake booster. In the case of a brake booster of the type in which the vacuum valve is opened and waits when there is no input from the brake pedal or the like, air is introduced into the first working pressure chamber and the second working pressure chamber simply by switching the switching valve to the atmosphere side. It is not necessary to provide the above-mentioned bypass and check valve since it flows in. Furthermore, in the case of a brake booster that does not perform brake control such as traction control, since only air in the first working pressure chamber and the second working pressure chamber is caused to flow out through the vacuum passage having the above-described configuration, the bypass, It is not necessary to provide a check valve, a switching valve for introducing air into the vacuum passage, and a controller.

Furthermore, although the passage tube 23 is described as being provided with a predetermined interval from the output shaft 19, a plurality of guide protrusions are provided on the inner wall of the passage tube in the circumferential direction, and the output shaft is guided by the guide protrusions. You may make it.

Furthermore, although the switching valve has been described as supplying the atmosphere, compressed air may be used as the atmosphere, whereby the responsiveness can be improved.

[Effects of the Invention] As described above, according to the present invention, air is moved through a vacuum passage, such as by letting air in a working pressure chamber flow out to a negative pressure source, and the power piston is moved with the movement of the air. When the power piston moves, the seal member forming the vacuum passage is fixed to the concave portion of the power piston and is fitted in an airtight manner with the outer periphery of the passage tube. It is possible to slide while maintaining the airtightness in the passage. Therefore, it is possible to provide a lightweight brake booster having a simple structure without using bellows.

[Brief description of the drawings]

FIG. 1 is a main sectional view showing a brake booster according to an embodiment of the present invention. 1 ... operating rod, 2 ... casing, 2a
... Front shell, 2b Rear shell, 4 Negative pressure source, 6 Second constant pressure chamber (constant pressure chamber), 8 First constant pressure chamber (constant pressure chamber), 9 Air passage, 11 ... First working pressure chamber (working pressure chamber), 13 ... Second working pressure chamber (working pressure chamber), 18 ... Power piston, 19 ... Output shaft, 22 ... Vacuum passage, 23 ...
Passage tube, 24 recess, 25 seal member, 26 internal passage, 31 atmospheric valve, 32 vacuum valve.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B60T 13/52-13/577

Claims (1)

(57) [Claims] 1. A casing having a front shell disposed on a master cylinder side for generating brake hydraulic pressure and a rear shell disposed on an operating rod side for receiving an input from a brake pedal, and a casing communicating with a negative pressure source. A constant-pressure chamber in the casing, an operating pressure chamber in the casing communicating with the negative pressure source through a vacuum passage having a vacuum valve, and communicating with the atmosphere through an atmosphere passage having an atmosphere valve; and the constant-pressure chamber. And a power piston that moves between the constant pressure chamber and the working pressure chamber according to the pressure difference between the constant pressure chamber and the working pressure chamber to drive the output shaft, and the power piston is directed toward the working pressure chamber. A brake booster having a biasing return spring, wherein the vacuum passage communicates with the negative pressure source and is airtightly fixed to the front shell. A passage pipe extending in a rear shell direction so as to cover the output shaft; a recess formed around the output shaft of the power piston; an outer periphery of the passage pipe fixed to an opening of the recess. A seal member that fits airtightly and slides on the passage pipe with the movement of the power piston; and an internal passage provided inside the power piston and communicating the recess with the vacuum valve. A brake booster characterized by being constituted.