Motors: expansible chamber type – Working member position feedback to motive fluid control – Follower type
Patent
1994-05-20
1996-12-31
Nguyen, Hoang
Motors: expansible chamber type
Working member position feedback to motive fluid control
Follower type
91376R, F15B 910
Patent
active
055883460
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to pneumatic boosters, and more particularly boosters of the type of those which are used to provide boosted braking for motor vehicles.
Boosters of this type conventionally comprise a casing inside which there is a piston including a hub extended backwards by a tubular part passing in a sealed fashion through the casing and supporting a skirt and which, with the aid of a rolling seal, defines a front chamber permanently connected to a source of depression and a back chamber selectively connected to the front chamber or to the atmosphere by a valve means actuated by a control rod capable of pressing, by means of the front face of a plunger, on a first face of a reaction disk secured by a second face to a push rod.
In such pneumatic boosters, the piston hub consists of a single-piece solid component in which the tubular part extending backwards outside the housing is extended, forwards, by a flared part on the periphery of which are mounted the skirt and the seal and in which are arranged the plunger and the reaction disk, in a configuration which is intricate to produce, taking into account in particular the communication channels and the surface finish required for the back tubular part, and has a significant overall weight.
The object of the present invention is to propose a pneumatic booster of the type defined in general above, of lighter, robust design, low manufacturing cost and which allows, simply by interchanging components of subassemblies, various adaptations suiting different vehicles provided with such boosters for assisting braking.
In order to do this, according to one feature of the invention, the back tubular part of the piston is connected to the piston hub by clipping.
Advantageously, provision may be made for the piston hub to comprise an annular groove so as to receive an internal peripheral bead of the rolling seal, the bead coming to bear on the front end of the back tubular part.
By virtue of such a design, it is possible to make provision for the back tubular part of the piston and the piston hub to consist of different materials.
In addition, with such a configuration, the body part of the hub is reduced to a core of small dimensions and low weight of compact shape giving no manufacturing problems, it being possible for the components of the piston to be assembled easily and in an automated way allowing numerous point modifications.
Other features and advantages of the present invention will emerge from the following description of one embodiment given by way of non-limiting example with reference to the appended drawing in which:
BRIEF DESCRIPTION OF THE DRAWINGS
The single FIGURE is a view in partial longitudinal section of a pneumatic booster for assisting braking. The lower half of the figure represents a conventional pneumatic booster, and the upper half represents a pneumatic booster produced in accordance with the present invention.
DETAILED DESCRIPTION OF THE DRAWINGS
By convention, the part of the booster located on the brake pedal side is called the "back" and the part located on the master cylinder side is called the "front". In the figure, the front is thus to the left and the back is to the right.
The lower half of the single figure shows the back central part of a pneumatic brake booster of the vacuum type, including a casing of which the central part of the back cover 10 can be recognized, divided internally into a front chamber, or vacuum chamber 12, and a back chamber, or working chamber 14 by a movable wall structure consisting of a skirt 16 and of a flexible seal 18 of which the external peripheral edge (not shown) is fixed in a sealed fashion between the two shells of the case.
The skirt 16 is supported by a piston 20 including a structure essentially comprising a hub part 22, and a back tubular part 24 which interacts, with sealed sliding on its periphery, with a guiding and sealing assembly 26 mounted in a back tubular central portion of the back cover 10. The hub is formed with a peripheral groove 29 receiving a bead 19 co
REFERENCES:
patent: 4658704 (1987-04-01), Mori et al.
patent: 5105721 (1992-04-01), Furuta et al.
patent: 5433135 (1995-07-01), Watanabe
patent: 5976032 (1995-12-01), Gautier et al.
Gautier Jean Pierre
Perez Revilla Miguel
Verbo Ulysse
AlliedSignal Europe Services Techniques
McCormick Jr. Leo H.
Nguyen Hoang
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