JPS6235938B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a tandem brake booster,
More specifically, it consists of a valve body with a built-in valve mechanism that controls the opening and closing of a pressure fluid flow path in accordance with the forward and backward movements of an input shaft, and a hub that is disposed on the front end surface of this valve body and into which the end of the push rod is inserted. Regarding the coupler structure.

Conventionally, in a tandem type brake booster,
It is known that a valve body housing the above-mentioned valve mechanism and a hub into which the distal end of the push rod is fitted are constructed separately and connected together. In a tandem brake booster, at least the valve body, the rear power piston, and the front power piston need to be integrally molded or connected, and also include a cylindrical member that slidably passes through the center plate that partitions the inside of the shell. Various assembly structures have been proposed as necessary. Among these, since the valve body and hub are separated, the number of parts increases, so many assembly structures have been proposed, but the ease of assembly and the degree of freedom in design depend on the configuration. have a major impact on

The present invention provides a tandem type brake booster having a novel configuration that can improve assembly workability and has a large degree of freedom in design. In the present invention, the axial length of the hub is relatively long, and a center body is provided on the outer periphery of the hub, and this is used as a cylindrical part that slidably passes through the center plate, Further, the valve body and the center body are integrally connected by a first stopper and a second stopper provided on the hub by using the hub as a connecting member. With this configuration, when the parts around the valve body are temporarily assembled, they can be connected together using the second stopper on the front power piston side, so for example, it is possible to assemble them on the rear power piston side. In comparison, work efficiency can be improved, and the degree of freedom in design can be increased, such as by making it possible to form an air passage inside the center body.

The present invention will be described below with reference to the illustrated embodiments.
In Figure 1, 1 is a front shell, 2 is a rear shell, and inside the sealed container composed of both shells 1 and 2 is a center plate 3, a front diaphragm 4
and four chambers A by the rear diaphragm 5,
It is divided into B, C, and D. The above-mentioned front shell 1 has a cup-like shape as a whole, and has a stepped portion 1a formed in the middle of the cylindrical portion, a medium diameter cylindrical portion 1b on the opening side, and a small diameter cylindrical portion 1c on the opposite side. An engaging stepped portion 1d is formed at the open end of the diameter cylindrical portion 1b, and the opening portion is defined as a large diameter cylindrical portion 1e.

The center plate 3 has a cup shape with a depth approximately half that of the front shell 1, and its cylindrical portion 3
A is fitted into the medium-diameter cylindrical portion 1b of the front shell 1, and a flange portion 3b bent radially outward is formed at the open end of the cylindrical portion 3a, and this is brought into contact with the engagement step portion 1d. Positioning is performed by bringing them into contact. An annular engagement groove 3d that opens approximately radially outward is formed in the bent portion of the cylindrical portion 3a of the center plate 3 and the end wall portion 3c connected thereto. 3d and the inner surface of the small diameter cylindrical portion 1c of the front shell 1 sandwich the outer peripheral bead portion 4a of the front diaphragm 4 to keep that portion airtight.

Further, an annular engagement groove 2a corresponding to the annular engagement groove 3d is formed on the outer circumference of the substantially dish-shaped rear shell 2, and an outer circumferential end continuous with the annular engagement groove 2a is extended radially outward. The flange portion 2b is directed toward the flange portion 2b. The outer circumferential bead portion 5a of the rear diaphragm 5 is held between the inner surface of the annular engagement groove 2a and the inner surface of the cylindrical portion 3a of the center plate 3 to keep that portion airtight, and the flange portion 2b of the rear shell 2 is The outer surface of the flange portion 2b of the rear shell 2 is supported by a plurality of engaging pawls 1f formed on the large diameter cylindrical portion 1e of the front shell 1 in a state in which the rear shell 2 is overlapped on the flange portion 3b of the center plate 3. This is to prevent it from slipping out.

However, 6 is a synthetic resin valve body housing a conventionally well-known valve mechanism 7 inside, and the cylindrical portion 6
a is slidably protruded outward from an opening 2c formed in the shaft portion of the rear shell 2 via a seal member 8, and a dust cover 9 is attached between the protruding end and the opening 2c. A small diameter portion 10a at the right end of a reaction disk hub 10 made of metal is slidably fitted into the shaft portion of the valve body 6, and a stopper 11 attached to the end of the small diameter portion 10a is brought into contact with the stepped portion of the valve body 6. This prevents the reaction disk hub 10 from slipping out to the left. The inner peripheries of the rear diaphragm 5 and the rear power piston 13 are inserted between the right end surface of the synthetic resin center body 12 slidably fitted around the outer periphery of the hub 10 and the left end surface of the valve body 6. The front diaphragm 4 and the front power piston 1 are sandwiched between the left end surface of the center body 12 and the nut 14 screwed onto the hub 10.
5, and in this state, tighten the nuts 14.
By tightening, the valve body 6, rear diaphragm 5, rear power piston 13, center body 12, front diaphragm 4, and front power piston 15 are integrally fastened between the stopper 11 and the nut 14.
The center body 12 slidably passes through the shaft portion of the center plate 3 while maintaining airtightness with a seal member 16 attached thereto.

By the way, in this embodiment, a notch 10b is formed at the tip of the hub 10, that is, the threaded part of the nut 14, and the front power piston 15 is inserted into this notch.
When the nut 14 is tightened, the front power piston 15 is prevented from rotating along with the nut 14 by engaging the engaging portion 15a formed on the inner circumference of the front power piston 15. This prevents the front diaphragm 4 from being assembled in a twisted state due to the rotation of the front diaphragm 4. FIG. 2 is a cross-sectional view taken along the - line in FIG.
On the other hand, the engaging portion 15 of the front power piston 15
A has a hole 15b that connects both notches 10b and allows the rod portion 17a of the push rod 17 to loosely fit through the hole 15b. As shown in FIG. 1, this push rod 17 has a large diameter portion 17b at its base slidably fitted into the large diameter portion 10c of the hub 10.
The rod portion 17a is brought into contact with the end surface of the reaction disk 18 housed in the rod portion 0c, and the tip of the rod portion 17a is slidably projected to the outside from the shaft portion of the front shell 1 via the seal member 19.

In such a configuration, the hub 10 and the front power piston 15 have their cutouts 10b.
The front power piston 15 does not rotate with the rotation of the nut 14 when the nut 14 is tightened because the front power piston 15 is integrally connected in the rotational direction by engagement with the engaging portion 15a. Therefore, the front diaphragm 4 disposed on the back side of the front diaphragm 4 is not twisted as the front diaphragm 4 rotates, and a decrease in durability caused by being assembled in a twisted state can be prevented. In addition, the above-mentioned engaging part 1
5a has the rod portion 17a of the push rod 17 passed through the hole 15b, so that the large diameter portion 17b of the push rod 17 is connected to the large diameter portion 10 of the hub 10.
It is also possible to prevent the situation from escaping from c.

Further, in this embodiment, the stopper 11 is fitted onto the outer circumferential end of the reaction disk hub 10 and rotated 90 degrees to be attached to the hub 10. That is, Figures 3 and 4
As shown in the figure, a pair of notches 10d are formed by cutting out the upper and lower positions of the distal end of the hub 10, and a pair of engaging parts 10e are formed between both notches 10d. An engagement groove 10f with which the stopper 11 engages is formed on the outer periphery. On the other hand, the stopper 11 is ring-shaped as a whole, and has an inner circumferential portion that passes through the pair of engaging portions 10e of the hub 10 when the distal end of the hub 10 is inserted therein. A pair of notches 1
1a, and an engaging portion 11b that is positioned within the engaging groove 10f of the engaging portion 10e when the stopper 11 is rotated 90 degrees from that state.

In order to maintain the engagement state between the engagement groove 10f and the engagement portion 11b, a notch 11c is formed on the outer periphery of the stopper 11, and the notch 11c is expanded into the shaft hole of the valve body 6 along its axial direction. The protruded bulge 6
b, thereby preventing the stopper 11 from rotating relative to the valve body 6, and the hub 10 is inserted through the valve body 6 and the hub 10 in the radial direction thereof, as shown in FIG. The key 20 prevents rotation relative to the valve body 6. This key 20
is provided to prevent the valve plunger 21 which is slidably fitted into the small diameter portion 10a of the hub 10 from coming off, and as is well known in the art, its tip is divided into two parts in the form of a fork, and there is a fork-shaped part in between. A small diameter portion of the valve plunger 21 is engaged. In addition, key 20
is prevented from falling off from the valve body 6 by a retaining ring 33. Further, the valve plunger 21 constitutes a part of the above-mentioned valve mechanism 7, and its end is connected to an input shaft 22 that is linked to a brake pedal (not shown), and its tip is opposed to the end surface of the reaction disk 18. There is.

Next, the aforementioned chamber A was communicated with an intake manifold (not shown) via the negative pressure introduction pipe 23 attached to the front shell 1, and this chamber A was bored in the large diameter portion 10c of the reaction disk hub 10. It is constantly communicated with the chamber C via the through hole 24, a first passage 25 formed in the center body 12, and a lateral hole 26 communicating with the passage 25. Furthermore, when the brake booster is not in operation, these chambers A and C are connected to a hole 27 formed in the rear power piston 13, a passage 28 formed in the valve body 6, and a gap between the valve body and the valve seat of the valve mechanism 7. and communicates with the chamber D via a radial passage 29 formed in the valve body 6, and a passage 3 formed in the valve body 6.
It also communicates with the chamber B via a second passage 31 formed in the center body 12 and the center body 12 . In this state, negative pressure is introduced into each of the chambers A, B, C, and D, making them equal pressures, and there is no pressure difference between the front and back of each diaphragm 4, 5, so that the pressure is reduced by the return spring 32. and is held in the non-operating position shown.

As understood from the above-mentioned structure of passage relations,
In this embodiment, the first
Since it is necessary to connect the passage 25 and the second passage 31 to the passage 28 and the passage 30 of the valve body 6 while maintaining airtightness separately, a sealing member is required to maintain airtightness between these passages, but in this embodiment, In order to simplify the configuration of this part and facilitate assembly, a part of the rear diaphragm 5 can be used as the sealing member. 5 is a front view showing the left end surface of the valve body 6, and FIG. 6 is a front view showing the inner peripheral part of the rear diaphragm 5 superimposed on the left end surface. A large-diameter annular groove 6c that collectively surrounds the outer periphery of the pair of passages 30 that communicate with the first passage 25 and the pair of second passages 31, and continuous with this annular groove 6c, Each of the above pair of passages 30
A small-diameter annular groove 6d is formed that surrounds only the groove.

Further, a passage 30 formed in the valve body 6
Enlarge the opening on the left end side of the engaging recess 6e.
At the same time, as shown in FIG.
The valve body 6 and the center body 12 can be positioned in the rotational direction by forming a protrusion and engaging the two. Note that the passage 28 on the valve body 6 side is provided at only one location because it is necessary to form a hole through which the key 20 is passed at an axially symmetrical position, but the first passage 25 of the center body 12 that communicates with this passage is axially symmetrical with the passage 28. There are two symmetrically located valve body 6 and center body 1.
2, even if the rotational direction position of the center body 12 is shifted by 180 degrees, no problem will occur.

On the other hand, as shown in FIG. 6, the inner peripheral bead portion of the rear diaphragm 5 has seal portions 5b, 5c that coincide with the annular grooves 6c, 6d, and therefore engages with the small diameter annular groove 6d. Sealing portion 5c that fits
has the protrusion 1 of the center body 12 inside it.
It has an engagement hole 5d into which the screw 2a is inserted. Further, as shown in FIG. 1, the inner circumference of the rear power piston 13 extends to the outer circumference of an annular protrusion 6f formed on the shaft portion of the left end surface of the valve body 6, through which the protrusion 12a of the center body 12 is inserted. It has a pair of holes and the hole 27 described above. A pair of holes 27 are also provided at axially symmetrical positions.

In such a configuration, the connecting portion between the passage 30 and the second passage 31 is sealed by the seal portion 5c of the rear diaphragm 5, and the connecting portion between the first passage 25 and the passage 27 is sealed by the rear diaphragm 5. The seal members 34 provided on the seal portions 5b and 5c of the hub 10 and the small diameter portion 10a of the hub 10 provide a seal.

Note that the operation when the valve mechanism 7 is operated is the same as the operation of a conventionally known tandem type brake booster, so a description of the operation will be omitted. Further, in the above embodiment, the stopper 11 as the first stopper and the hub 10 are separate bodies, but they may be integrated. In this case, the stopper 11 is allowed to be inserted from the front side of the valve body 6,
In addition, in order to prevent the hub 10 from rotating 90 degrees and coming off, a means similar to the bulge 6b in FIG. 3 can be used, and the key 20 can be used as a rotation prevention means after rotation. Alternatively, the stopper 11 may be omitted from the above embodiment, and the key 20 may be replaced with the stopper 1.
It is also possible to use it as 1. On the other hand, as the second stopper, in addition to the nut 14 described above, a snap ring or the like can be used.

As described above, according to the assembly configuration of the present invention, it is possible to expect the effects of improving assembly workability and increasing the degree of freedom in design.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, except for the key 20, and FIGS.
A sectional view taken along the - line in the figure, Figure 2 is the first
A sectional view taken along the line - in the figure, FIG. 3 shows the reaction disc hub 10 and stopper 1 in FIG. 1.
1, FIG. 4 is a perspective view showing the right end of the reaction disk 10, FIG. 5 is a front view showing the left end of the valve body 6 in FIG. 1, and FIG. FIG. 6 is a front view of the inner peripheral portion of the rear diaphragm 5 superimposed on the left end surface of the valve body 6. FIG. 3... Center plate, 6... Valve body, 7... Valve mechanism, 10... Hub, 11... Stopper, 12... Center body, 13... Rear power piston, 14... Nut, 15... Front power Piston, 17... Push rod, 2
2...Input shaft.

Claims (1)

[Scope of Claims] 1. A valve body incorporating a valve mechanism that controls the opening and closing of a pressure fluid flow path in accordance with the forward and backward movement of an input shaft, a hub disposed on the front end surface of this valve body, and a terminal disposed within this hub. A tandem brake booster comprising a push rod fitted with a push rod, and a front power piston and a rear power piston that operate in response to fluid pressure from the valve mechanism and transmit thrust to the push rod; A first stopper is provided that engages with the valve body to prevent the hub from slipping out to the front side of the valve body, and a center body that slidably passes through the center plate of the tandem brake booster is provided on the outer periphery of the hub. The valve body is arranged so that its rear end is connected to the front end of the valve body, and further engaged with the front end of the center body at the front of the hub to prevent the center body from slipping out to the front side. A second stopper is provided, and the first stopper provided on the hub and the second stopper are provided.
A tandem brake booster characterized in that the valve body and center body are integrally connected by a stopper.