JPH032453Y2 - - Google Patents

Description

[Detailed description of the invention] "Field of industrial application" This invention relates to a tandem brake booster, and more specifically to valve bodies, rear power pistons,
and connection structures for front power pistons, etc.

``Prior Art'' Conventionally, in a tandem brake booster, it is necessary to connect at least the valve body, rear power piston, and front power piston together, and various types of connection structures have been proposed. As a conventional connection structure, as disclosed in Japanese Patent Application Laid-open No. 128951/1983, the end of a hub is engaged and connected to the valve body, and the rear power piston and center plate are slid onto this hub. A structure has been proposed in which a center body that freely moves through the valve body and a front power piston are sequentially assembled, and finally a nut is screwed onto the tip of the hub to sandwich and connect them to the valve body.

By the way, in order to connect the rear power piston, center body, and front power piston between the end of the hub and the nut, make sure that the end of the hub does not come out of the valve body when tightening the nut. There is a need to. At the same time, in order to make the nut tightening work easier, when the nut is tightened with the valve body supported, at least the hub is connected to the valve body so that it cannot rotate relative to the valve body. It is necessary to prevent it from rotating.

In the conventional connection structure described in the above-mentioned publication,
After the hub is fitted into the valve body, a stopper is attached to the distal end of the hub, and this stopper prevents the hub from coming out forward from the valve body. In addition, the rotation of the hub relative to the valve body is prevented by using a key that prevents the valve plunger that constitutes the valve mechanism from coming out of the valve body.
This is done by inserting this key into the valve body and hub.

``Problems to be Solved by the Invention'' However, such a connection structure has the drawback that the number of parts increases at least by the stopper, and an assembly operation is required to assemble the parts.

In a brake booster designed to reduce stroke loss at the initial stage of depression of the brake pedal, the key cannot be used as a means for preventing rotation of the valve body of the hub. That is, in such a brake booster, the key for preventing the valve plunger from coming off is movable in the axial direction of the valve body, and the key is brought into contact with the inner surface of the shell when the brake booster is inactive. A valve plunger interlocked with the key is positioned in a forward position relative to the valve body, so that the flow path switching operation of the valve mechanism can be performed immediately when the next brake pedal is depressed.

Therefore, when the above-mentioned key is used as a means for preventing rotation of the hub against the valve body, the key may become caught between the hub and the valve body due to their relative rotation, and the key may become stuck due to the relative rotation between the hub and the valve body. If it becomes impossible to displace in the axial direction, the above-mentioned loss stroke reduction function will be impaired.

In view of these circumstances, the present invention has been developed to prevent the hub from being pulled out of the valve body with a simple structure without using a key, and at the same time to prevent relative rotation between the hub and the valve body. To provide a tandem brake booster that allows easy installation work.

``Means for Solving the Problems'' That is, the present invention forms an engaging portion projecting radially outward at the distal end of the hub, and allows the engaging portion to pass through the shaft portion of the valve body. forming an axial groove that engages the engaging portion, and forming an engaging recess that is circumferentially displaced from the axial groove, and engaging the engaging portion with the engaging recess. This is how it was done.

"Operation" According to the above configuration, the engaging part of the hub is passed along the axial groove of the valve body, and then the hub is rotated relative to the valve body, so that the engaging part of the hub is engaged with the engaging recess of the valve body. If they are matched, the engagement between the two can simultaneously prevent the hub from coming off forward and rotating relative to the valve body.

"Example" The present invention will be explained below with reference to the illustrated example.
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 front shell 1 as a whole is formed into a cup shape, and a stepped portion 1a is formed in the middle of the cylindrical portion so that the diameter becomes smaller on the front side.

The center plate 3 is formed into a tap shape having approximately half the depth of the front shell 1 and is fitted into the front shell 1, and the outer circumference of the front surface of the center plate 3 and the stepped portion 1a of the front shell 1 are connected to each other. are opposed in the axial direction, and the outer peripheral portion of the front diaphragm 4 is held between them. Further, the outer circumferential portion of the rear diaphragm 5 is sandwiched between the inner surface of an annular engagement groove 2a formed on the outer circumferential portion of the substantially dish-shaped rear shell 2 and the inner surface of the cylindrical portion of the center plate 3.

However, 6 is a valve body made of synthetic resin that houses a conventionally known valve mechanism 7 inside, and a hub 8 made of metal is fitted to the shaft portion of this valve body 6 while maintaining airtightness with a seal member 9. Part 8
At the same time, the hub 8 is prevented from slipping out to the left by engaging the engaging portion 8b integrally provided at the end of the valve body 6 with the engaging recess 6a formed in the valve body 6.
The valve body 6 and hub 8 are prevented from rotating relative to each other.

As shown in FIG. 2, the engaging portions 8b formed on the hub 8 are formed to protrude radially outward on both sides of the right end small diameter portion 8a of the hub 8, and on the other hand, on the valve body 6. forms an axial groove 6b that allows the engagement part 8b to pass through, and an engagement part 8 at a position rotated 90 degrees from the axial groove 6b.
b forms the above-mentioned engagement recess 6a that engages. Therefore, if the engaging portion 8b of the hub 8 is passed through the axial groove 6b and then rotated 90 degrees to engage the engaging portion 8b into the engaging recess 6a, the hub 8 It is possible to prevent the hub 8 from coming off the valve body 6, and at the same time, it is possible to prevent the hub 8 from rotating relative to the valve body 6.

A center body 10 made of synthetic resin is fitted around the outer periphery of the hub 8.
The inner peripheral parts of the rear diaphragm 5 and the rear power piston 11 are sandwiched between the right end surface of the center body 10 and the left end surface of the valve body 6, and a nut is screwed onto the left end surface of the center body 10 and the hub 8. 12, the inner periphery of the front power piston 13 is sandwiched between the sealing member 14 and the nut 12 in an airtight manner, and the nut 12 is tightened in this state.
Between the valve body 6, rear diaphragm 5, rear power piston 11, center body 1
0. The front power pistons 13 are integrally connected to each other.

At this time, by forming a protrusion 10a on the right end surface of the center body 10 and engaging the protrusion 10a with a recess 6c formed on the left end surface of the valve body 6, the valve body 6 and the center body 10 are relatively It is connected so that it does not rotate. Further, a cylindrical portion 13a protruding toward the rear power piston 11 is formed on the shaft portion of the front power piston 13, and this is fitted into the shaft portion of the center body 10, and a radius continuous with the cylindrical portion 13a is formed. As shown in FIG. 3, the inward flange portion 13b is engaged with the oval-shaped stepped portion 8c formed at the base of the threaded portion of the hub 8, so that the two do not rotate relative to each other. I have to.

Therefore, since the hub 8 and the front power piston 13, the valve body 6 and the center body 10, and the hub 8 and the valve body 6 are each fixed in the rotational direction, the front power piston 13 is supported and fixed. When the nut 12 is tightened in this state, there is no relative rotational displacement of each component.

The valve plunger 20 constituting the valve mechanism 7 is slidably fitted into the small diameter portion 8a at the right end of the hub 8, and the end of the valve plunger 20 is connected to an input shaft 21 that is linked to a brake pedal (not shown). The distal end thereof is opposed to the end surface of a reaction disk 22 provided within the large diameter portion 8d of the hub 8. The opposite end surface of this reaction disk 22 is
The base portion is in contact with the right end surface of a push rod 23 that is slidably fitted into the large diameter portion 8d of the hub 8, and the tip of the push rod 23 is slid from the shaft portion of the front shell 1 via a seal member 24. It is freely movable and protrudes to the outside.

The key member 25 that prevents the valve plunger 20 from coming off the hub 8 is interlocked with the valve plunger 20 by penetrating the valve body 6 and the hub 8 in their radial directions, and is provided with an appropriate stopper (not shown). This means prevents it from falling out of the valve body 6. At this time, as shown in FIGS. 1 and 4, the valve body 6 is formed with a radial hole 26 through which the key member 25 is inserted. , a bridge portion 6d is integrally formed that penetrates the inside of the bifurcated portion of the key member 25 and connects the front and rear parts.
d allows the strength of the valve body 6 to be increased.

Further, the key member 25 is connected to the valve body 6.
and the hub 8 so as to be slidable in the axial direction thereof, and the valve body 6 and the power piston 1
1, 13, etc. are held in the non-operating position shown by the return spring 27, the key member 25 is brought into contact with the inner wall surface of the rear shell 2, and the valve plunger 20 and input shaft 21 are allowed to freely retreat. The valve body 28 of the valve mechanism 7 is moved forward from the position to the valve seat 29.
, in order to reduce the invalid stroke of the input shaft 21 at the initial stage of operation.

Next, the aforementioned chamber A is a constant pressure chamber into which negative pressure is constantly introduced, and is communicated with an intake manifold (not shown) via a negative pressure introducing pipe 30 attached to the front shell 1. Also, this constant pressure chamber A
are the through hole 31 drilled in the flange portion 13b of the front power piston 13, and the center body 10.
It is constantly communicated with the constant pressure chamber C via a first passage 32 formed in the.

Furthermore, when the brake booster is not operating, these constant pressure chambers A and C are connected to a hole 33 formed in the rear power piston 11 and a passage 3 formed in the valve body 6.
4. The gap between the valve body 28 and the valve seat 29 of the valve mechanism 7 and the radial passage 3 formed in the valve body 6
The passage 36 communicates with the variable pressure chamber D via the valve body 5 and is further formed in the valve body 6 and the center body 1.
It also communicates with the variable pressure chamber B via a second passage 37 formed at 0.0.

In this state, negative pressure is introduced into each of the constant pressure chambers A, C and variable pressure chambers B, D, making them equal pressures, and there is no pressure difference between the front and back of each diaphragm 4, 5, so that the return spring 27
is held in the non-operating position shown.

In this embodiment having the above configuration, the hub 8
The engaging portion 8b provided on the small diameter portion 8a at the right end is passed through the axial groove 6b formed in the shaft portion of the valve body 6 to protrude to the right side of the axial groove 6b, and then the hub 8 is rotated 90 degrees. By then engaging the engaging portion 8b into the engaging recess 6a, it is possible to easily prevent the hub 8 from slipping off from the valve body 6, and at the same time prevent the hub 8 from rotating relative to the valve body 6. It can be prevented.

And valve body 6 and center body 10
are the protrusion 10a and recess 6c formed respectively.
The hub 8 and the front power piston 13 are prevented from rotating relative to each other by the oval-shaped stepped portion 8c formed on the hub 8, so the front power piston 13 can be supported by hand. When the nut 12 is tightened in a fixed state, there is no relative rotational displacement of each component, and reliable tightening can be performed.

In the above embodiment, because the center body 10 is formed with passages 32, 33, and 37 that communicate between the constant pressure chambers A and C and between the variable pressure chambers B and D, the connection between the center body 10 and the valve body 6 is Although it is necessary to perform positioning in the rotational direction, there is no need to align the positions of the shells 1 and 2, as is the case when the passages are formed on the outer periphery of the shells 1 and 2 as is well known in the art. Of course, when the nut 12 is tightened, it is sufficient to simply connect the hub 8 and the valve body 6 in the rotational direction.

"Effect of the invention" As described above, according to the invention, the hub can be moved forward from the valve body by simply passing the engaging part provided on the hub through the axial groove of the valve body and then engaging the engaging recess. Since it is possible to prevent the hub from being pulled out and at the same time to prevent it from rotating relative to each other, it is possible to assemble the hub to the valve body extremely easily.Moreover, it does not require a stopper like in the past, which reduces costs accordingly. Furthermore, since the key is not used as a rotation prevention means unlike in the conventional case, the present invention has the advantage that it can also be applied to a loss stroke reduction type brake booster.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing one embodiment of the present invention;
The figure is an exploded perspective view showing the connection between the valve body 6 and the hub 8, and Figure 3 is the front power piston 13.
FIG. 4 is a cross-sectional view taken along the - line in FIG. 1. 1...Front shell, 2...Rear shell, 3
... Center plate, 6 ... Valve body, 6
a... Engagement recess, 6b... Axial groove, 8... Hub, 8b... Engagement part, 10... Center body,
12... Nut, 11... Rear power piston,
13...Front power piston.

Claims (1)

[Claims for Utility Model Registration] A hub that is fitted onto the shaft of a valve body to prevent it from coming out forward from the valve body, and a hub that is fitted around the outer periphery of the hub and slidably passes through the center plate. , and a tandem brake booster comprising: a center body that holds a rear power piston between the valve body; and a front power piston that holds a front power piston between the center body and a nut screwed onto the tip of the hub. , an engaging part protruding radially outward is formed at the distal end of the hub, an axial groove is formed in the shaft part of the valve body for allowing the engaging part to pass through, and the axial groove and the circular groove are formed. A tandem brake booster characterized in that an engagement recess into which the engagement portion engages is formed at a position shifted in the circumferential direction, and the engagement portion is engaged with the engagement recess.