JP2817765B2 - Booster - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a booster, and more particularly, to a booster provided in a shell and having a stopper for regulating a forward end position of a valve body.

2. Description of the Related Art Conventionally, when the axial dimension of a shell in a booster is changed according to the type of a vehicle to be mounted, a valve body having a dimension basically adapted to the changed axial dimension of the shell. Such components are prepared and stored in a shell to manufacture a booster.

By the way, conventionally, since the structural members such as the valve body housed in the shell can be shared, the valve body and the like are required to be housed more than the shell having the axial dimension to be housed. It may be desired to house it in a shell with a long axial dimension. For example, there is a case where a valve body manufactured for a shell having an axial dimension of 110 mm is used in a shell having an axial dimension of 130 mm. In this case, the axial dimension of the shell is 13
Despite being 0 mm, the constituent members such as the valve body are manufactured according to the shell for the axial dimension of 110 mm, so that the advance stroke of the valve body and the like in the shell is increased by at least 20 mm. Therefore, when the booster is, for example, a tandem booster, the rear power piston connected to the outer peripheral portion of the valve body collides with the center plate provided at the axial center portion of the shell, or the rear seal member moves from the rear seal member to the rear of the valve body. There is a risk that the side ends will fall off. Further, when the booster is a single type booster, the bellows provided over the rear end of the valve body and the rear end of the shell may collide with the rear opening of the shell and be damaged. Therefore,
It is an object of the present invention to provide a booster in which common internal components can be used in shells of different axial dimensions.

That is, the present invention provides a valve body provided in a shell so as to be able to move forward and backward, a power piston provided on an outer peripheral portion of the valve body, and a shell which is stretched on a back surface of the power piston. A diaphragm that divides the inside into a constant-pressure chamber on the front side and a variable-pressure chamber on the rear side, a cylindrical part formed by extending axially rearward on a shaft part on the front side of the shell, and provided on the front side inside the shell Contacting the valve body when the valve body is advanced,
In a booster provided with a first stopper for regulating the forward end position, the booster is attached to the cylindrical portion of the shell,
When the valve body is advanced, an annular second stopper is provided which comes into contact with the valve body and regulates a forward end position of the valve body at a position rearward of the first stopper portion.

According to this structure, when the second stopper is not attached to the cylindrical portion, the forward end position of the valve body is regulated by the first stopper. When attached to the
The forward end position of the valve body is regulated by the second stopper on the rear side of the first stopper. Therefore, for example, a component such as a valve body manufactured for a shell having an axial length of 110 mm is replaced with an axial length of 130 m.
The second stopper may be attached to the tubular portion when the device is housed in the m shell and manufactured. By manufacturing the booster in this way, it is possible to prevent the advance stroke of the valve body in the shell from being unnecessarily increased, thereby preventing the power piston or the like from being damaged. Thus, by providing the first stopper and the second stopper, a common component such as a valve body can be used in shells having different axial dimensions.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 shows the inside of a tandem brake booster. The inside of a shell 1 is divided into two front and rear spaces by a center plate 2, A substantially cylindrical valve body 3 is slidably penetrated through the shaft of the center plate 2. The valve body 3 has a large-diameter portion 3a and a small-diameter portion 3b, and has a radially outer portion on the outer periphery of the front end of the large-diameter portion 3a, which is the most front side (left side) of the valve body 3. A flange portion 3c bulging out is formed. The shaft portion of the front power piston 4 is attached to the flange portion 3c to prevent the front power piston 4 from falling off by an annular retainer 5, and the shaft portion of the rear power piston 6 is attached to the outer periphery of the rear end of the large diameter portion 3a. The connection is prevented by the retainer 7 from falling off. A front diaphragm 8 and a rear diaphragm 9 are provided on the back surfaces of the power pistons 4 and 6, respectively. A constant pressure chamber A and a variable pressure chamber B are formed before and after the front diaphragm 8, and the rear diaphragm 9 is A constant pressure chamber C and a variable pressure chamber D are formed before and after. The constant pressure chambers A and C communicate with each other via a constant pressure passage 12 formed in the valve body 3 and communicate with a negative pressure source via a negative pressure introducing pipe (not shown) connected to the front side wall surface of the shell 1. Therefore, a negative pressure is always introduced into both the constant pressure chambers A and C. The two pressure change chambers B and D communicate with each other via a pressure change passage 13 formed in the valve body 3. A conventionally well-known valve mechanism 16 including a vacuum valve 14 and an atmospheric valve 15 is provided in the valve body 3, and a space outside the atmospheric valve 15 is provided through the constant pressure passage 12 to both the constant pressure chambers A. , C, and a space between the atmospheric valve 15 and the vacuum valve 14 communicates with a rear-side variable pressure chamber D via a radial variable-pressure passage 17 provided in the valve body 3. The inside of the vacuum valve 14 communicates with the atmosphere via a pressure passage 18 formed in the valve body 3. Further, a cylindrical portion 1a extending toward the rear side is formed on a shaft portion on the front side of the shell 1, and a rear end of the cylindrical portion 1a is bent inward in the radial direction. It is a part 1b. An annular seal member 2 is provided between the inner peripheral surface of the cylindrical portion 1a and the outer peripheral portion of the output shaft 19.
2 is kept airtight. And the input shaft 23
The vacuum valve 14 and the atmospheric valve 15 that constitute the valve mechanism 16 are opened and closed with the advance and retreat, and the two constant pressure chambers A and C are opened and closed.
And the state of communication between the two transformer chambers B and D can be switched. When the booster in which the input shaft 23 is advanced is operated, an output of a predetermined servo ratio can be obtained from the output shaft 19. In a non-operation state in which the input shaft 23 is not advanced, the constituent members such as the valve body 3 are stopped at the non-operation position in the figure by the urging force of the return spring 24. The above-described configuration and the operation based on the configuration are the same as those of the conventionally known tandem brake booster. In this embodiment, on the premise of the above-described configuration, an annular stopper 25 that is pressed into the cylindrical portion 1a of the shell 1 is provided. This stopper 25
The forward end position of the valve body 3 can be switched between the case where the valve body 3 is fitted into the cylindrical portion 1a and the case where the stopper 25 is not fitted. As shown in FIGS. 2 to 4, the stopper 25 includes a fitting portion 25 </ b> A press-fitted into the cylindrical portion 1 a and the front end surface 3 of the valve body 3.
d and a contact portion 25B that contacts the
A frusto-conical guide portion 25C is provided on the shaft portion of the rear end surface on the 5B side. A plurality of plate-shaped engagement pieces 25a are formed in the stopper 25 in the axial direction at equal intervals on the same circumference on the front end face, and the fitting portion 25A is formed by the plurality of engagement pieces 25a. Is composed. A small hemispherical projection 25b is provided inside the tip of each of the engagement pieces 25a. And fitting part 2
The inner part of each engagement piece 25a constituting 5A
a from the rear side while being pressed into the outer peripheral portion of
The stopper 25 is positioned in the axial direction with respect to the cylindrical portion 1a by bringing the inner end surface of the stopper 5a into contact with the locking portion 1b. At this time, in this embodiment, each engaging piece 25a can be elastically deformed radially outward by its own elasticity, and each engaging piece 25a is in point contact with the outer peripheral surface of the cylindrical portion 1a. The joint piece 25a is pressed into the cylindrical portion. Therefore, as compared with the case where the fitting portion 25A is formed of a cylindrical portion continuous in the circumferential direction, the engagement piece 25a as the fitting portion 25A with a small pressure input.
Can be press-fitted into the cylindrical portion 1a. The end face located between the guide portion 25C and the contact portion 25B is located axially forward of the contact portion 25B, thereby forming a substantially annular groove on the rear end surface. doing.
After the front end of the return spring 24 is fitted to the guide portion 25C, the return spring 24 is brought into contact with the annular groove-shaped end surface. Further, the contact portion 25B
A plurality of grooves 25c penetrating in the radial direction are formed at circumferentially equal intervals in, and a space on the radially inner side and a space on the outer side of the contact portion 25B are formed by these grooves 25c. And can be communicated.
By press-fitting the stopper 25 configured as described above into the cylindrical portion 1a of the shell 1, constituent members such as the valve body 3 set to the same dimensions can be shared by the shells 1 having different axial dimensions. That is, for example, in FIG. 1, when the dimensions of the components such as the valve body 3 housed in the shell 1 are manufactured so as to be compatible with the shell 1 having the axial dimension of 110 mm, these components are , In the case where it is used as a component in the shell 1 having an axial dimension of 130 mm. In this case, as shown in FIG. 1, the stopper 25 is attached to the cylindrical portion 1a of the shell 1 having an axial dimension of 130 mm to manufacture a booster. Thus, when the valve body 3 is advanced during operation, the front end face 3d of the valve body 3 abuts against the abutting portion 25B of the stopper 25, whereby the forward end position of the valve body 3 is regulated. You. Therefore,
Although the valve body 3 for the shell 1 having the axial dimension of 110 mm is used in the shell 1 having the axial dimension of 130 mm, the valve body 3 has the axial dimension of 110 m.
and stops at the same forward end position as when it is stored in the shell 1 of m. On the other hand, the axial dimension is 130 mm without attaching the stopper 25 to the cylindrical portion 1a.
When the valve body 3 or the like for the shell 1 having an axial dimension of 110 mm is used in the shell 1 having a diameter of 110 mm, the constituent members such as the valve body 3 have a difference in dimension between the two shells 1 in the axial direction.
It moves forward by an extra mm. At that time, the rear power piston 6 collides with the center plate 2 and is broken. Thus, in this embodiment, by attaching the stopper 25 to the tubular portion 1a, a common member such as the valve body 3 can be used for the shells 1 having different axial dimensions. Note that the axial dimension is 13
In the case where a component such as the valve body 3 manufactured so as to conform to the axial dimension is used in the 0 mm shell 1, it is not necessary to attach the stopper 25 to the cylindrical portion 1a. In this case, the front end face 3d of the valve body 3 which is advanced at the time of operation comes into contact with the head of the mounting bolt 27 which fixes the reinforcing plate 26 to the shell 1,
The forward end position is regulated. As described above, according to the present embodiment, not only the mounting bolt 27 having the function as the original stopper but also the stopper 25 is provided separately therefrom. Components of the same dimensions, such as the valve body 3, can be used. Further, since the stopper 25 is configured such that the fitting portion 25A is composed of a plurality of engagement pieces 25a and the projections of the engagement pieces 25a are in point contact with the tubular portion 1a, the fitting portion 25A is formed in a cylindrical shape. When press-fitting into the part 1a,
A small press input is sufficient. Further, the contact portion 2 of the stopper 25
Since a plurality of grooves 25c as communication passages are formed in the valve body 5B, when the front end surface 3d of the valve body 3 comes into contact with the contact portion 25B and is prevented from moving forward, the groove 25c is formed.
The constant pressure chamber A and the constant pressure passage 12 of the valve body 3 can communicate with each other via c. Therefore, when the valve body 3 returns from the operating state in which the front end face 3d of the valve body 3 abuts on the abutting portion 25B to the non-operating state shown in FIG. The fluid is smoothly discharged into the constant pressure chamber A via the groove 25c. Therefore, the valve body 3 can quickly return from the operating state to the non-operating state. In the above embodiment, the present invention is applied to a tandem brake booster. However, a single type brake booster and a triple type brake booster having three pairs of a constant pressure chamber and a variable pressure chamber in the shell 1 are described. Of course, it can be applied to a force device.

As described above, according to the present invention, there is obtained an effect that a common internal component can be used in shells having different axial dimensions.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention.

FIG. 2 is a front view of a stopper 25 shown in FIG. 1;

FIG. 3 is a right side view of FIG. 2;

FIG. 4 is a left side view of FIG. 2;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Shell 1a Cylindrical part 3 Valve body 3d Front end face of valve body 4 Front power piston 6 Rear power piston 8 Front diaphragm 9 Rear diaphragm 25 Stopper (second stopper) 27 Mounting bolt (first stopper) 25A Fitting part 25B Contact part 25a Engagement piece 25c Groove (communication passage) A, C Constant pressure chamber B, D Transformation chamber

Claims (2)

(57) [Claims] 1. A valve body provided in a shell so as to be able to move forward and backward, a power piston provided on an outer peripheral portion of the valve body, a constant-pressure chamber on a front side and a rear side extending from the power piston to a rear side of the power piston. And a cylindrical section formed by extending axially rearward on a shaft portion on the front side of the shell, and provided on the front side in the shell, when the valve body is advanced. A booster having a first stopper that abuts the valve body and regulates a forward end position of the valve body. The booster is attached to a cylindrical portion of the shell, and the valve body is advanced when the valve body is advanced. A booster, wherein an annular second stopper is provided in contact with the body to regulate a forward end position of the valve body on a rear side of the first stopper portion. 2. The second stopper includes a fitting portion fitted to the cylindrical portion of the shell, and a contact portion abutting on a front end surface of the valve body, wherein the fitting portion includes a shaft. A plurality of engagement pieces extending toward the front side, and the abutting portion is configured such that, when abutting against the end surface of the valve body, a space on the radially inner side of the abutting portion and the outer side. The booster according to claim 1, further comprising a communication path that communicates with a space on the side.