JPH03295749A - Booster - Google Patents

Abstract

PURPOSE:To prevent the reduction of the strength of a valve body by constituting the valve body of a booster with the first and second cylindrical members, and using a space in the axial direction formed with the outer periphery of the first cylindrical member and the inner periphery of the second cylindrical member as variable-pressure passage. CONSTITUTION:A nearly cylindrical valve body 6 is slidably inserted airtightly by circular seal members 7, 8 into the shaft sections of a rear shell 2 and a center plate 3 of a booster, and a valve mechanism 15 switching the fluid circuits between two constant-pressure chambers A, C and two variable-pressure chambers B, D is provided in the valve body 6. The valve body 6 is constituted of the first cylindrical member 41 inserted into the outer periphery section on the rear side from the opening of the rear shell 2 to the outside and the second cylindrical member 42 coupled on the outer periphery section of the first cylindrical member 41. The space at the middle portion of inner and outer circular sheet sections is communicated to the variable-pressure chamber D via a variable-pressure passage 26 in the radial direction formed on the valve body 6, and the variable-pressure chamber D is communicated to the variable- pressure chamber B via another variable-pressure passage 27.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a booster, and more particularly, to an improvement in a variable pressure passage formed in a valve body of a brake booster, for example.

``Conventional technology'' Conventionally, as a booster, there is a center plate that divides the inside of the shell into a front chamber on the front side and a rear chamber on the rear side, and a center plate that is slidably fitted in an airtight manner. A valve body, a front power piston provided in the valve body located in the front compartment, a rear power piston provided in the valve body located in the rear compartment, and a front power piston stretched across the front power piston and the shell. A front diaphragm that divides the interior into a constant pressure chamber on the front side and a variable pressure chamber on the rear side, and a front diaphragm stretched across the rear power piston and the shell to divide the rear interior into a constant pressure chamber on the front side and a variable pressure chamber on the rear side. A device comprising a rear diaphragm that partitions, a constant pressure passage that communicates the constant pressure chamber of the front chamber and the constant pressure chamber of the rear chamber, and a variable pressure passage that communicates the variable pressure chamber of the front chamber and the variable pressure chamber of the rear chamber. Are known.

``Problems to be Solved by the Invention'' By the way, the variable pressure passage is usually constituted by a hole formed in the axial direction of the valve body and a hole in the radial direction continuous from the axial hole, and both ends of the variable pressure passage are The end of the hole was opened to the circumferential surface of the valve body and the end surface of the stepped portion.

In this way, conventionally, the variable pressure passage was constructed by the axial hole and the radial hole provided in the valve body.
Forming these axial holes and radial holes has the disadvantage that the strength of the valve body is reduced.

"Means for Solving the Problem" In view of such circumstances, the present invention provides the booster described above, in which the valve body is connected to a first cylindrical member that connects the front power piston and the front diaphragm, and a first cylindrical member that connects the front power piston and the front diaphragm. a second cylindrical member attached to the outer periphery of the first cylindrical member, slidably penetrating the center plate in an airtight manner, and connecting the rear power piston and the rear diaphragm; The axial space defined by the outer circumferential surface of the first cylindrical member and the inner circumferential surface of the second cylindrical member is used as the variable pressure passage.

"Function" According to such a configuration, it is not necessary to form an axial hole and a radial hole in the solid part of the valve body as in the conventional case. Since the axial space defined by the inner peripheral surface of the member can be configured as the variable pressure passage, the strength of the valve body can be improved compared to the conventional valve body.

Embodiment J The present invention will be described below with reference to the illustrated embodiment. In FIG.
It is divided into two chambers, a front chamber 4 and a rear chamber 5, and a generally cylindrical valve body 6 is provided in the details of the rear shell 2 and the center plate 3, each of which is sealed airtight by an annular seal member 7.8. It is held in place and is slidably penetrated.

The valve body 6 includes the front chamber 4 and the rear chamber 5.
The front power piston 9 and the rear power piston 10 housed in each are connected, and a front diaphragm 11 and a rear diaphragm 12 are respectively stretched on the rear surface of each power piston 9 and 10, and a constant pressure is maintained before and after the front diaphragm 11. A chamber A and a variable pressure chamber B are formed, and a constant pressure chamber C and a variable pressure chamber are also formed before and after the rear diaphragm 12.

The valve mechanism F that switches the fluid circuit between the two constant pressure chambers A and C and the two variable pressure chambers B and D is the valve body 6.
The valve mechanism 15 includes an annular first valve seat 16 formed in the valve body 6 and an annular first valve seat 16.
an annular second valve seat 18 formed at the right end of the valve plunger 17 slidably provided on the valve body 6 on the inner side thereof;
Then, apply spring 1 to both valve seats 16 and 18 from the right side in Figure 1.
and a valve body 20 seated by 9.

A space on the outer peripheral side of the annular seat portion where the first valve seat 16 and the valve body 20 contact is communicated with the constant pressure chamber A via an axial constant pressure passage 21 formed in the valve body 6. This constant pressure chamber A is communicated with an intake manifold (not shown) via a negative pressure introduction pipe 22 attached to the front shell 1.

Further, the constant pressure chamber A is communicated with the constant pressure chamber C via a second constant pressure passage 23 formed in the valve body 6 in the axial direction.

On the other hand, a portion on the inner circumference side of the annular seat portion where the first valve seat 16 and the valve body 20 contact, and an outer circumference side of the annular seat portion where the second valve seat 18 and the valve body 20 contact; In other words, the space between the inner and outer annular seat portions is the space between the valve body 6
The variable pressure chamber is communicated with the variable pressure chamber B through a radial variable pressure passage 26 formed in the valve body 6, and the variable pressure chamber B is communicated with the variable pressure chamber B via another variable pressure passage 27 formed in the valve body 6.

Further, the space on the inner peripheral side of the inner annular seat portion where the second valve seat 18 and the valve body 20 contact is communicated with the atmosphere via the filter 28.

Valve plunger 1 slidably provided on the valve body 6
The right end of 7 is connected to an input shaft 29 that is linked to a brake pedal (not shown), and its left end is opposed to the right end surface of the reaction disc 31 in the recess 30b formed in the base 30a of the bushing rod 30. There is. The left end of the bushing rod 30 is connected to a sealing member 32.
The shaft opening 1a of the front shell 1 is slidably protruded from the shaft opening 1a of the front shell 1 to be interlocked with a piston of a master cylinder (not shown). In addition, the valve body 6 is
It is always biased toward the rear side by the return spring 33, and is normally located at the non-operating position shown in the figure, where the key member 34 engaged with the valve plunger 17 and the valve body 6 is in contact with the inner wall surface of the rear shell 2. There is.

The above configuration is basically the same as that of a conventionally known tandem brake booster.

However, the valve body 6 in this embodiment includes a first cylindrical member 41 located on the detail side and whose rear side outer peripheral portion is passed through the opening of the rear shell 2 to the outside, and this first cylindrical member 41.
It is made up of two members: a second cylindrical member 42 that is fitted into the outer peripheral portion located inside the shell.

The above-described valve mechanism 15 and the base portion 30a of the bushing rod 30 are housed inside the first cylindrical member 41, and the constant pressure passage 21 and variable pressure passage 26 are formed, and the key member 34 is engaged. I try to let them do it.

The outer circumferential portion of the first cylindrical member 41 is formed into a stepped cylindrical shape with the diameter becoming smaller on the rear side, and is formed into a large diameter portion 41a, a medium diameter portion 41b, and a small diameter portion 41c from the front side to the rear side. Furthermore, a flange portion 41d that bulges radially outward is formed at the front end of the large diameter portion 41a.

In this embodiment, an engaging portion 41e consisting of an annular groove is formed on the outer peripheral surface of the rear side of the flange portion 41d of the first cylindrical member 41, and the front power piston 9 is formed in the engaging portion 41e.
The inner circumferential cylindrical portion 9a of the front diaphragm 11 and the inner circumferential bead portion 11a of the front diaphragm 11 are overlapped with each other, and these portions are press-fitted from the rear side toward the front side and connected.

On the other hand, the second cylindrical member 42 is provided with a stepped through hole whose diameter increases on the front side in accordance with the shape and dimensions of the large diameter portion 41a1 and the medium diameter portion 41b on the first cylindrical member 41 side. As described above, from the state in which the inner peripheral cylindrical part 9a of the front power piston 9 and the inner peripheral bead part 11a of the front diaphragm 11 are connected to the flange part 41a of the first cylindrical member 41, this second cylindrical member At the same time as fitting the large diameter hole 42a of the member 42 into the large diameter portion 41a of the first cylindrical member 41 from the rear side,
The small diameter hole 42b of the second cylindrical member 42 is fitted into the medium diameter portion 41b of the first cylindrical member 41 from the rear side.

When the second cylindrical member 42 is fitted into the first cylindrical member 41, the step end surface 42c of the second cylindrical member 42 is aligned with the first cylindrical member 41.
It comes into contact with the stepped end surface 41f of the cylindrical member 41,
As a result, the second cylindrical member 42 fitted into the first cylindrical member 41 is positioned in the axial direction.

Depth (axial dimension) of large diameter hole 42a of second cylindrical member 42
is set to be slightly shorter than the axial dimension of the large diameter portion 41a of the first cylindrical member 41. Therefore, when the second cylindrical member 42 is fitted into the first cylindrical member 41 as described above, In the positioned state, a required gap is formed between the rear side end surface of the flange portion 41d of the first cylindrical member 41 and the front side end surface of the second cylindrical member 42.

Further, an annular groove 42d with a predetermined depth and width is formed on the rear side end surface of the second cylindrical member 42 positioned in this way, and the inner peripheral edge of the rear power piston 10 is formed within the annular groove 42d. The stepped cylindrical portion 10a is fitted into the rear power piston 10, and the rear is inserted into the annular space formed by the inner circumferential surface of the stepped cylindrical portion 10a of the rear power piston 10 and the inner circumferential surface of the annular groove 42d. By fitting the inner peripheral bead portion 12a of the diaphragm 12, the rear power piston IO and the rear diaphragm 12 are connected to the second cylindrical member 42 (valve body 6).

Then, the annular groove 42 of the second cylindrical member 42
The stepped cylindrical portion 10 of the bower piston 10 is connected to d.
A required gap is formed between the outer circumferential surface of a and the outer circumferential surface of the annular groove 42d, and between the rear end surface of the second cylindrical member 42 and the bower piston lO located opposite thereto. There is.

Further, on the shaft side of the rear end surface of the second cylindrical member 42 in this state, a substantially U-shaped key member 43 (see FIG. 2) attached to the middle diameter portion 41b of the first cylindrical member 41 is attached. are engaged and locked in that position, thereby preventing the second cylindrical member 42 from falling off from the first cylindrical member 41.

In addition, when locking the second cylindrical member 42 to the first cylindrical member 41 with the key member 43 in this way, the outer peripheral portion of the key member 43 is is brought into pressure contact with the rear diaphragm 12 from the rear side toward the front side. This prevents the stepped cylindrical portion 10a of the rear power piston 10 and the inner peripheral bead portion 12a of the rear diaphragm 12 from falling off from the annular groove 42d of the second cylindrical member 42.

Further, at predetermined positions on the outer peripheral surfaces of the large diameter portion 41a and the medium diameter portion 41b of the first cylindrical member 41, an axial groove 41 is formed from a position adjacent to the rear end surface of the flange portion 41d toward the rear side.
g is provided. In this embodiment, the axial space formed by the axial groove 41g of the first cylindrical member 41 in the connected state and the inner peripheral surface of the through hole of the second cylindrical member 42 allows the above-mentioned Transforming pressure passage 2 that communicates pressure chambers B and D
7.

Further, an axial through hole 41h is formed in the first cylindrical member 41 at a position 180 degrees shifted from the position of the axial groove 41g, and the front side end of this through hole 41h is connected to the return spring 33. The rear end of the through hole 41h is opened at the step end surface 41i on the inner circumferential side with which it comes into contact, while the rear end of the through hole 41h is opened at the step end surface 41f of the large diameter section 41a. Further, in accordance with the position of the through hole 41h of the first cylindrical member 41, an axial through hole 42f penetrating from the step end face 42c to the annular groove 42d is formed in the second cylindrical member 42. There is. A space is formed by the through holes 41h and 42f of these two members, the outer peripheral surface of the annular groove 42d of the second cylindrical member 42, and the outer peripheral surface of the stepped cylindrical portion 10a of the rear power piston 10. By,
The constant pressure passage 23 is configured to communicate the defined pressure chambers A and C.

In this embodiment, when connecting the through holes 41h and 42f of both members, the rear side opening of the through hole 41h on the first cylindrical member 41 side is made to protrude in a cylindrical shape toward the rear side to form a convex portion. On the other hand, a recess is formed in the end face of the stepped portion, which is the opening of the through hole 42f on the second cylindrical member 42 side, in accordance with the position of the projection, and the projection and the recess are engaged with each other. By engaging these convex portions and concave portions,
Each transformer passage 27 constituted by both members 41 and 42,
The constant pressure passage 23 is aligned.

In addition, on the constant pressure passage 23 side, a rubber seal member 44 is attached to the inner peripheral surface of the recess on the second cylindrical member 42 side so that the seal does not leak from the engaged recess and recess.

As described above, in this embodiment, the variable pressure passage 27 is formed in the axial hole S provided in the solid portion of the valve body 6 as in the conventional case.
The valve body 6 itself is made up of a first cylindrical member 41 and a second cylindrical member 42, rather than being composed of a first cylindrical member 41 and a second cylindrical member 42.
The first cylindrical member 41
The axial groove 41g on the outer circumferential surface of the second cylindrical member 42 and the inner circumferential surface of the second cylindrical member 42 constitute a variable pressure passage 27. Therefore, the strength of the valve body 6 can be improved compared to the conventional structure in which an axial hole and a radial hole are provided in the solid portion of the valve body 6 and the holes are configured as the variable pressure passage 27.

Further, in this embodiment, as described above, the voltage changing passage 27 is connected to the inner peripheral surface of the stepped hole of the second cylindrical member 420 and the outer periphery of the large diameter portion 41a and the medium diameter portion 41b of the first cylindrical member 41. Since it is constituted by the axial groove 41g formed in the transformer passage 2,
The rear end opening of 7 can be located radially inward compared to the front end opening. Therefore, the stepped cylindrical portion 10a of the rear power piston 10, which is always connected to the radially outward side of the rear end opening of the variable pressure passage 27, is larger than the valve body 6 (
The attachment position to the second cylindrical member 42) can be moved radially inward and connected, thereby reducing the outer diameter dimension of the second cylindrical member 42 (valve body 6). It is.

That is, conventionally, the opening 1a of the front shell 1 through which the bushing rod 30 is penetrated is enlarged, and the rear end of a mask cylinder (not shown) is accommodated in the front shell 1 through the enlarged opening 1a. In a tandem brake booster in which the axial dimension of the entire booster is shortened, the rear end of the mask cylinder is housed at a position on the inner circumferential side of the return spring 33. In that case, , it is necessary to set the inner diameter of the large diameter hole 41j of the first cylindrical member 41, which is on the front side of the step end face 41i with which the rear end of the return spring 33 comes into contact, to be large, and accordingly, the valve The outer diameter of the body 6 was increased.

Furthermore, in such a tandem brake booster in which the rear end of the mask cylinder is accommodated in the front shell 1 through the opening 1a of the front shell 1, in order to form the pressure transformation passage 27 in the valve body 6, the large diameter is required. Hole 41j
An axial passage is formed in a solid portion of the valve body 6 that is radially outward.

In order to form the axial passage, it is necessary to form the valve body 6 in a straight line in the axial direction due to the relationship with the cutting die. If these are formed with their positions shifted inward and outward in the radial direction as in the illustrated embodiment,
Two parallel cutting dies that form each axial passage and a radial cutting die that communicates both axial passages are required, and the opening on the outer periphery of the valve body formed by the radial cutting die is required. A closing member is required and its manufacture is complicated.

Therefore, the connecting position of the stepped cylindrical portion 10a of the rear power piston 10 connected to the valve body 6 is radially outward from the position of the rear end opening of the variable pressure passage 27 formed in a straight line in the valve body 6. Therefore, the stepped cylindrical portion 10 of the rear power piston 10 must be provided at a position radially outward from the rear end opening of the variable pressure passage 27.
There is a drawback that the outer dimensions of the valve body 6, which is the connecting position of the stepped cylindrical portion 10, become larger as the stepped cylindrical portion 10 has to be connected.

To address these conventional drawbacks, this embodiment has the following points:
The rear end opening of the variable voltage passage 27 is located radially inwardly than the front opening thereof, and therefore, the second The stepped cylindrical portion 10a of the rear power piston 10 connected to the cylindrical member 42 is connected at a radially inward position compared to the conventional one described above, so the stepped cylindrical portion 10a is connected to the second cylindrical member 42 (
The three dimensions of the outer diameter of the valve body 6) can now be made smaller than those of the conventional valve body, which in turn can reduce the weight of the entire booster.

Further, in this embodiment, the constant pressure passage 2 of the valve body 6 is
3 is an axial through hole 41 formed in both members 41 and 42.
h, 42f% and an annular groove 42d provided on the end surface of the second cylindrical member 42. Therefore, the opening that becomes the rear end of the constant pressure passage 23 as in the conventional case is located on the outer periphery of the valve body 6. Therefore, when the brake booster is activated, forward force is transmitted to the valve body 6 via both power pistons 9 and 10, but the accompanying force inside the valve body 6 is The internal stress generated in the constant pressure passage 23 is not concentrated at the openings forming both ends of the constant pressure passage 23. Therefore, compared to the conventional case in which the ends of the constant pressure passage 23 are opened on the outer peripheral surface of the valve body, the internal stress generated in the valve body 6 is further reduced. can improve the strength of

In the above embodiment, the axial groove 41g on the outer peripheral surface of the first cylindrical member 41 and the inner peripheral surface of the second cylindrical member 42 constitute the variable pressure passage 27, but the second cylindrical member 42 A variable pressure passage can be formed by forming a groove on the inner peripheral surface of the first cylindrical member 41 and the outer peripheral surface of the first cylindrical member 41 .

Further, in the above embodiment, the present invention is applied to a brake booster, but it is of course applicable to a clutch booster.

Further, in the above embodiment, the constant pressure passage 23 is formed in the valve body 6, but the constant pressure passage is formed in the shell 1 as is conventionally known.
It may be formed on the outer periphery of the.

"Effects of the Invention" As described above, according to the present invention, the strength of the valve body can be improved compared to the conventional one.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG.
FIG. 2 is a sectional view of a main part taken along the line ■-■ in the figure. 1...Front shell 2...Rear shell 3...
・Center plate 4...Front chamber 5...Rear chamber 6...Valve body 9...Front power piston 10...Rear power piston 11...Front diaphragm 12...Rear diaphragm 27... - Variable pressure passage 41...first cylindrical member 42...second cylindrical member

Claims (1)

[Scope of Claims] A center plate that divides the interior of the shell into a front chamber on the front side and a rear chamber on the rear side, a valve body that is slidably fitted to the center plate in an airtight manner,
A front power piston provided on the valve body located in the front compartment, a rear power piston provided in the valve body located in the rear compartment, and a stretched structure extending between the front power piston and the shell to move the front compartment toward the front side. a front diaphragm that partitions the rear chamber into a constant pressure chamber and a variable pressure chamber on the rear side; and a rear diaphragm that extends across the rear power piston and the shell and partitions the rear chamber into a constant pressure chamber on the front side and a variable pressure chamber on the rear side. and a booster comprising: a constant pressure passage that communicates the constant pressure chamber of the front chamber with a constant pressure chamber of the rear chamber; and a variable pressure passage that communicates the variable pressure chamber of the front chamber with the variable pressure chamber of the rear chamber; The valve body includes a first cylindrical member connecting the front power piston and the front diaphragm, and a valve body that is attached to the outer circumference of the first cylindrical member and slidably penetrates the center plate in an airtight manner. , and a second connecting the rear power piston and the rear diaphragm.
A booster comprising a cylindrical member, the axial space formed by the outer circumferential surface of the first cylindrical member and the inner circumferential surface of the second cylindrical member being the pressure-changing passage.