JPH02114057A - Brake force boosting device - Google Patents

Abstract

PURPOSE:To prevent delay in operation of a braking force boosting device by arranging a pair of constant pressure chamber and varying pressure chambers in a shell in three rows, putting the varying pressure chamber of the central chamber with a valve mechanism in the shortest way via a varying pressure passage, and thereby quickly exhausting the pressure fluid from each varying pressure chamber. CONSTITUTION:A front chamber 6, central chamber 8, and rear chamber 9 are partitioned in a shell 1 consisting of a front shell 2 and a rear shell 3, and power pistons 14-16 are fitted in these chambers 6, 8, 9, respectively. A valve body 12 is slidably installed on the shaft part in this shell 1. In this type of braking force boosting device, the space in the middle of No.1, No.2 valve seats 24, 26 and two ring-shaped seat parts with which a valve body 28 is in contact is put in communication with a varying pressure chamber D of the central chamber 8 via No.1 varying pressure passage 33. No.2 varying pressure passage 34 in the axial direction in communication with a varying pressure chamber B of the front chamber 6 and No.3 varying pressure passage 35 in the axial direction in communication with a varying pressure chamber of the rear chamber are put in communication with a valve mechanism 23 through No.1 varying pressure passage 33.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a brake booster including a constant pressure chamber and a variable pressure chamber within a shell.

``Prior Art'' A brake booster normally has a power piston and a diaphragm in its shell that define a pair of constant-pressure chambers and variable-pressure chambers at the front and rear of the shell, and when the brake pedal is released and the brake pedal is not activated, the brake boosters are Negative pressure is introduced into the constant pressure room and the variable pressure room.

When the brake pedal is depressed, while negative pressure is introduced into the constant pressure chamber, atmospheric pressure is introduced into the variable pressure chamber according to the force applied to the brake pedal, creating a fluid pressure difference before and after the power piston. The power piston and the bushing rod interlocked therewith are advanced, and the advancement of the bushing rod advances the piston of the master cylinder to generate brake fluid pressure.

By the way, in order to increase the output in this type of brake booster, it is sufficient to increase the effective pressure receiving area of the power piston, but if the diameter of the power piston is increased for this purpose, the diameter of the brake booster also increases. , it may not be possible to install it depending on the vehicle.

For this reason, a tandem brake booster has conventionally been proposed in which two sets of a constant pressure chamber and a variable pressure chamber are arranged in series within the above-mentioned shell (Japanese Patent Publication No. 44-9770, Japanese Patent Publication No. 53
-23913, JP-A-60-154952).

According to the above tandem brake booster, the output can be increased without increasing the diameter even if the tandem brake booster becomes longer in the axial direction, so it can be installed on vehicles that cannot be equipped with a brake booster with a large diameter. becomes possible.

``Problems to be Solved by the Invention'' However, when attempting to further increase the output of a tandem brake booster, the diameter cannot be avoided. Even if the increase in diameter was suppressed, there were some vehicles whose diameter was too large to be mounted.

In order to improve these drawbacks, a triple type brake booster may be constructed in which three sets of a constant pressure chamber and a variable pressure chamber are arranged in series within the shell.

That is, a front plate and a rear plate are arranged and fixed inside the shell and divide the inside of the shell into a front chamber, a center chamber, and a rear chamber, and a valve is disposed to slidably penetrate the front plate and the rear plate. a body, a front power piston, a center power piston, and a rear power piston arranged in the front compartment, a center compartment, and a rear compartment, respectively, and connected to the valve body; and the front power piston, center power piston, and rear power piston. a front diaphragm stretched over each rear side and partitioning each of the front interior, center interior, and rear interior into a constant pressure chamber on the front side and a variable pressure chamber on the rear side;
A constant pressure passage that communicates between the center diaphragm and rear diaphragm and the constant pressure chambers formed in the front, center and rear compartments, and a constant pressure passage that communicates between the variable pressure chambers formed in the front, center and rear compartments. a variable pressure passage that communicates with the valve; a valve mechanism that is housed in the valve body and switches the communication state between the constant pressure passage, the variable pressure passage, and the pressure passage that supplies pressure fluid; The brake booster may be configured to include an input shaft that switches the flow path of the valve mechanism according to the operation.

According to the brake booster having such a configuration, a constant pressure chamber and a variable pressure chamber are defined before and after the front power piston, center power piston, and rear power piston, respectively, so compared to a tandem brake booster,
It is possible to increase the total effective pressure receiving area without increasing the diameter, and therefore to obtain the required large output even if the outside diameter of the brake booster is reduced, making it possible to use a brake booster with a larger diameter. It is possible to increase the possibility of mounting on vehicles that cannot be mounted.

However, in the triple type brake booster described above, when the brake booster is activated, pressure fluid is introduced into the variable pressure chamber in the rear chamber through the valve mechanism, and then from the variable pressure chamber in the rear chamber through the variable pressure passage formed in the valve body. When pressure fluid is introduced into the pressure change chambers of the center chamber and front chamber, the distance between the front chamber and the rear chamber increases, and the length of the pressure change passage formed in the axial direction of the valve body increases. It gets longer.

Therefore, especially when the pressure fluid supplied to the variable pressure chamber in the front chamber is released to the variable pressure chamber in the rear chamber through the pressure variable passage, the pressure fluid may not be discharged smoothly, which may cause a delay in the release of the brake. There was a risk that this could occur.

"Means for Solving the Problems" In view of such circumstances, the present invention adopts the configuration of the triple type brake booster described above, and further connects the pressure transformation passage with the pressure transformation chamber of the center chamber and the valve. A first variable pressure passage that communicates with the variable pressure mechanism, a second variable pressure passage that communicates the variable pressure chamber of the front chamber with the valve mechanism, and a third variable pressure passage that communicates the variable pressure chamber of the rear chamber with the valve mechanism. In addition, the length of the first variable pressure passage is shorter than that of the other variable pressure passages.

"Operation" According to the above configuration, the variable pressure chamber of the center chamber communicates with the valve mechanism via the first variable pressure passage through the shortest distance,
Since the pressure change chamber in the center chamber is located between the pressure change chamber in the front room and the pressure change chamber in the rear room, the passage lengths of the first pressure change passage and the third pressure change passage can be distributed almost equally. As a result, each variable pressure passage communicates the valve mechanism and each variable pressure chamber with the shortest passage length.

Therefore, when the pressure fluid supplied to each pressure change chamber is released through each pressure change passage, the pressure fluid in each pressure change chamber can be quickly discharged, thereby reducing the delay in operation when the brake is released. It can be effectively prevented.

``Embodiment'' The present invention will be described below with reference to the illustrated embodiment. In the figure, a shell 1 of a brake booster includes a stepped cup-shaped front shell 2 and a generally shaped shape that seals the opening of the front shell 2. The stepped cup-shaped front shell 2 has a diameter gradually increasing from the bottom side to the opening side, thereby forming a small diameter portion 2.
A, a medium diameter portion 2B and a large diameter portion 2C are sequentially formed, and a large diameter cylindrical hooking portion 2D is further formed on the opening side of the large diameter portion 2C.

A front plate 5 formed into a stepped cup shape is fitted inside the front shell 2, and a front chamber 6 is defined between the end wall surface of the front plate 5 and the end wall surface of the front shell 2. is forming.

The front plate 5 includes a cylindrical portion 5A tightly fitted into the middle diameter portion 2B of the front shell 2, and a flange portion 5B formed at the right end of the cylindrical portion 5A and extending radially outward. , the flange part 5B is attached to the front shell 2
The front plate 5 is positioned relative to the front shell 2 by overlapping the step end surface 2a of the middle diameter portion 2B.

A cup-shaped rear plate 7 is fitted inside the front plate 5, and a center chamber 8 is defined between the end wall surface of the rear plate 7 and the end wall surface of the front plate 5. is forming. The cup-shaped retainer plate 7 includes a cylindrical portion 7A that is tightly fitted into the large diameter portion 2C of the front shell 2.
A flange portion 7 extending radially outward formed at the right end of A
B is the large diameter portion 2c of the front shell and the cylindrical hooking portion 2D.
The rear plate 7 is positioned with respect to the front shell 2 by overlapping the stepped end face 2b formed between the rear plate 7 and the front shell 2.

Further, the rear shell 3 is provided with a flange portion 3A extending radially outward on its outer peripheral portion.
A is fitted into the cylindrical hooking part 2D of the front shell 2 and overlapped with the flange part 7B of the rear plate 7, thereby creating a gap between the wall surface of the rear shell 3 and the end wall surface of the rear plate 7. A rear chamber 9 is formed in the rear chamber 9.

In this state, by curving a part of the cylindrical hooking part 2D inward in the radial direction to form a plurality of engagement claws 2C, the front shell 2, the front plate 5,
The rear plate 7 and the rear shell 3 are integrally connected to each other.

Next, on the outer periphery of the valve body 12, which is slidably provided on the shaft portion within the shell 1, a large diameter portion 12A, a medium diameter portion 12B, and a small diameter portion 12C are sequentially formed from the front side to the rear side. , their respective outer peripheries are passed through through holes formed at the central positions of the shafts of each of the plates 5.7 and the rear shell 3, and the sealing member 13 maintains airtightness between each of the through holes and the valve body I2. ing.

A front power piston 14, a center power piston 15, and a rear power piston 1 are provided in the front chamber 6, center chamber 8, and rear chamber 9, respectively.
At the same time, each power piston 14-16 is connected to the valve body 12, and a front diaphragm 17,
A center diaphragm 18 and a rear diaphragm 19 are respectively stretched, and each chamber 6.8.9 has constant pressure chambers A, C, and E located on the front side, and a variable pressure chamber B%D located on the rear side, It is divided into F.

However, in the axial direction within the shaft portion of the valve body 12,
Constant pressure chamber A of the front chamber 6 and constant pressure chamber C of the center chamber 8
A first constant pressure passage 20 is formed to communicate with the constant pressure chamber A of the front chamber 6 and a constant pressure chamber E of the rear chamber 9 is formed.

The right end portion of the constant pressure passage 20 communicates with an annular groove 12b formed in the step end face 12a between the large diameter portion 12A and the medium diameter portion 12B of the valve body 12, and also communicates with the annular groove 12b formed in the stepped end surface 12a between the large diameter portion 12A and the medium diameter portion 12B of the valve body 12. A stepped cylindrical portion 15a protruding toward the front side is formed on the shaft portion, and the stepped cylindrical portion 15a
The small diameter portion of the tip is fitted into the inner circumferential surface of the annular groove 12b, and at the same time, it is positioned by being brought into contact with the bottom of the annular groove 12b.

Therefore, the constant pressure passage 20 communicates with the annular groove 12b on the outer circumferential side of the stepped cylindrical portion 15a, and communicates with the stepped end surface 12a of the valve body 12 and the center power piston 15.
It is constantly in communication with the constant pressure chamber C of the center chamber 8 through a gap δ formed between the center chamber 8 and the constant pressure chamber C of the center chamber 8. In addition, reinforcing ribs 1 extending in the axial direction at predetermined intervals are provided on the outer peripheral surface of the annular groove 12b.
2c is formed.

Further, the inner bead portion 18a of the center diaphragm 18 is fitted inside the stepped cylindrical portion 15a, and the inner bead portion 18a prevents the constant pressure passage 20 from communicating with the variable pressure chamber. There is. The inner peripheral bead portion 18a is connected to a retainer 22 fitted on the outer periphery of the valve body 12.
This prevents it from falling out of the stepped cylindrical portion 15a.

The right end of the other constant pressure passage 21 is also configured to be substantially the same as the right end of the constant pressure passage 20, and with this configuration, the axial dimension of the valve body 12 can be shortened.

That is, as is conventionally known, when a radial hole corresponding to the gap δ is opened in the same diameter portion of the valve body 12, and the center power piston 15 is connected to the rear side of the opening of the hole, Since the valve body 12 receives forward force from the center power piston 15, the valve body on the rear side of the hole needs to have a wall thickness that provides sufficient strength.

On the other hand, according to the above structure, the gap δ between the step end face 12a and the center power piston 15 corresponds to the conventional hole, and there is no need for a thick wall on the rear side of the hole. The axial dimension of the valve body can be shortened. And the above center power piston 1
5 is connected to the small diameter portion of the valve body on the rear side of the stepped end face 12a, so that sufficient strength of the connected portion can be ensured.

In particular, as in this embodiment, if the center power piston 15 is connected to the valve body I2 within the annular groove 12b formed in the step end face 12a, the connecting portion and the stroke portion of the seal member 13 can overlap. Therefore, the layers can be shortened.

Next, a conventionally known valve mechanism 23 is installed in the valve body 12.
This valve mechanism 23 has a valve body 12.
an annular first valve seat 24 formed at the right end of a valve plunger 25 slidably provided on the valve body 12 inside the annular first valve seat 24; 26, and a spring 27 from the right to both valve seats 24 and 26.
and a valve body 28 seated by.

The space on the outer peripheral side of the annular seat portion where the first valve seat 24 and the valve body 28 contact is connected to the constant pressure chamber A of the front chamber 6 and the rear chamber through the second constant pressure passage 21 formed in the valve body 12. It communicates with the constant pressure chamber E of No. 9, and also communicates with the constant pressure chamber A described above.
is connected to a negative pressure source such as an intake manifold (not shown) via a negative pressure introduction pipe 32 attached to the front shell 2. The negative pressure introduced into the constant pressure chamber A is constantly introduced into the constant pressure chamber C of the center chamber 8 and the variable pressure chamber E of the rear chamber 9 through the constant pressure passages 20, 21.

Further, the inner peripheral side of the annular seat part where the first valve seat 24 and the valve element 28 contact, and the outer peripheral side of the annular seat part where the second valve seat 26 and the valve element 28 contact, that is, the open annular part. The space in the middle portion of the seat portion communicates with the variable pressure chamber of the center chamber 8 via a first variable pressure passage 33 formed in the valve body 12 in the radial direction. A second variable pressure passage 34 in the axial direction communicating with the variable pressure chamber B of the front chamber 6 and a third variable pressure passage 35 in the axial direction communicating with the variable pressure chamber F of the rear chamber 9 are respectively connected to the first variable pressure passage 33. The above valve mechanism 2 via
It is connected to 3.

Therefore, the variable pressure chambers B, D, and F communicate with each other via the three variable pressure passages 33 to 35, and the passage length of the first variable pressure passage 33 that communicates with the central variable pressure chamber is minimized. Since the transformer passages 34 and 35 communicating with the transformer chambers B and F on both sides are divided into left and right sides around the first transformer passage 33,
They are roughly equidistant. In other words, nine stations, each transformer passage 33 to 35
are connected to the valve mechanism 23 and each variable pressure chamber B with the shortest passage length, respectively.
, D, and F are brought into communication.

As a result, for example, the pressure change passage that communicates the rear side pressure change chamber F and the valve mechanism 23 is set to the shortest distance, and the pressure change chamber F is connected to the front side pressure change chamber B and the center pressure change chamber through the pressure change passages. If they are connected, the length of the passage between the front pressure variable chamber B and the rear pressure variable chamber F will be particularly long, but with the above configuration, the length of the passage can be substantially halved. Therefore, the flow path resistance can be reduced.

Further, a space on the inner peripheral side of the annular seat portion where the second valve seat 26 and the valve body 28 contact is communicated with the atmosphere via an axial pressure passage 36 and a filter 37.

Next, the right end of the valve plunger 25 slidably provided on the valve body 12 is connected to an input shaft 38 that is linked to a brake pedal (not shown), and its left end is connected to an input shaft 38 that is linked to a brake pedal (not shown).
It is made to face the right end surface of a reaction disk 40 housed in a recess 39a formed at the base of the bushing rod 39. The left end of the bushing rod 39 is a sealing member 41.
The valve body 12 is slidably protruded from the shaft of the front shell 2 to the outside through the valve body 2, and is linked to a piston of a master cylinder (not shown). ing.

The key member 43 that prevents the valve plunger 25 from falling off from the valve body 12 is displaceable in the axial direction of the valve body 12, and both ends of the key member 43 protrude from the outer circumferential surface of the valve body 12. It comes into contact with the rear plate 7 when the booster is inactive. In this state, the key member 43 is attached to the valve body 12.
The valve plunger 25 is restricted from freely retreating from the valve plunger 25, and when the brake pedal is depressed and the input shaft 38 moves to the left, the flow path of the valve mechanism 23 is immediately switched, so that the loss stroke of the input shaft 38 can be reduced. It has become.

If the key member 43 is brought into contact with the rear plate 7 inside the shell 1, even if the key member 43 contacts the rear plate 7 and a knocking sound is generated, it will be transmitted to the outside of the shell 1. It becomes possible to reduce the hitting sound that is generated.

In the above configuration, when the brake pedal is not depressed, the valve body 12 is held at the right rearward end position by the return spring 42, and the key member 43 is attached to the rear plate 7. It is stopped due to contact. The key member 43 advances the valve plunger 25 engaged therewith relative to the valve body 12, and as described above, when the brake pedal is depressed and the input shaft 25 is moved to the left, , immediately valve mechanism 2
The flow path No. 3 is in a state where it can be switched.

In the non-operating state, the valve body 28 is seated on the second valve seat 26 provided on the valve plunger 25, and the pressure passage 3 communicates with the atmosphere.
6 is closed, and the valve body 28 is slightly separated from the first valve seat 24, so that the variable pressure passages 33 to 35 are connected to the constant pressure passage 2.
Negative pressure is introduced into all chambers A to F in the shell 1 in communication with the shell 1 .

From this state, when the brake pedal is depressed and the input shaft 25 moves to the left, the valve body 28 immediately seats on the first valve seat 24, and the valve body 28 and the second valve seat 26 are separated from each other. , the communication between the constant pressure passage 21 and each of the variable pressure passages 33 to 35 is cut off, and the communication between the constant pressure chambers A, C, and E and the variable pressure chambers B, D, and F is cut off, and each of the variable pressure chambers B, D, and F is cut off. Atmosphere is introduced into the interior.

As a result, each constant pressure chamber A, C, E and each variable pressure chamber B, D, F
When a pressure difference occurs between them, each of the power pistons 14 to 16, the valve body 12, etc. are integrally moved to the left to advance the bushing rod 39, causing a master cylinder (not shown) to generate brake fluid pressure and perform brake operation. .

Further, when the brake pedal depression force is released from the brake operating state, the flow path of the valve mechanism 23 is switched to cut off the communication between the pressure conversion chambers B, D, and F and the atmosphere, and the pressure conversion chambers B, D, and D %F is communicated with the constant pressure chambers A, C, and H, so that the atmosphere in each of the variable pressure chambers B, D, and F escapes through the constant pressure chamber A to a negative pressure source (not shown).

At this time, each of the variable pressure passages 33 to 35 communicates the valve mechanism 23 with each variable pressure chamber B, D, and F through the shortest passage length, so that the atmosphere within each variable pressure chamber can quickly escape to the outside. Therefore, a delay in deactivation of the brake booster can be prevented.

"Effects of the Invention" As described above, according to the present invention, it is possible to communicate between the valve mechanism and each variable pressure chamber through the variable pressure passage that allows for the shortest passage length. When the pressure fluid supplied to the brake fluid is released through each variable pressure passage, the pressure fluid in each variable pressure chamber can be quickly discharged, and therefore, it is possible to effectively prevent a delay in operation when the brake fluid pressure is released. You can get the effect that you can.

[Brief explanation of the drawing]

The figure is a sectional view showing one embodiment of the present invention. 18- Center diaphragm 19- Rear diaphragm 20- First constant pressure passage 21- Second constant pressure passage 23-
・・Valve mechanism 33−・First pressure transformation passage 34−・・
Second pressure changing passage 35 - Third pressure changing passage 36 - Pressure passage 38 - Input shaft A, C, E - Constant pressure chamber B, D, F - Variable pressure chamber Patent applicant Jidosha Kiki Co., Ltd.

Claims (1)

[Scope of Claims] A front plate and a rear plate that are arranged and fixed inside a shell and divide the inside of the shell into a front chamber, a center chamber, and a rear chamber, and a front plate and a rear plate that are slidably penetrated through the front plate and the rear plate. a front power piston, a center power piston, and a rear power piston arranged in the front compartment, a center compartment, and a rear compartment, respectively, and connected to the valve body; and the front power piston, center power piston, and a front diaphragm, a center diaphragm, and a rear diaphragm that extend over each rear side of the rear power piston and partition the front interior, center interior, and rear interior into a constant pressure chamber on the front side and a variable pressure chamber on the rear side; A constant pressure passage that communicates between the constant pressure chambers formed in the front compartment, the center compartment, and the rear compartment; a variable pressure passage that communicates between the variable pressure chambers formed in the front compartment, the center compartment, and the rear compartment; and the valve body. a valve mechanism that is housed in the interior and switches the communication state between the constant pressure passage, the variable pressure passage, and the pressure passage that supplies pressure fluid; and a flow path of the valve mechanism that is moved forward and backward in conjunction with the brake pedal and responsive to its operation. and an input shaft for switching, and the voltage changing passage further includes a first voltage changing passage communicating between the pressure changing chamber of the center chamber and the valve mechanism, and a second voltage changing passage communicating the pressure changing chamber of the front chamber and the valve mechanism. and a third variable pressure passage communicating between the variable pressure chamber of the rear chamber and the valve mechanism, and the length of the first variable pressure passage is set shorter than the other variable pressure passages. booster.