Brake booster having means for mounting on a wall

Expansible chamber devices – With guide or seal on cylinder end portion for piston or...

Reexamination Certificate

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Details

C092S169300

Reexamination Certificate

active

06189437

ABSTRACT:

BACKGROUND OF THE INVENTION
It is common practice for a housing for a brake booster to be manufactured from a front shell which is joined to a rear shell through some type of lancing operation, such as disclosed in U.S. Pat. No. 4,267,766. In this type booster, the front shell and the rear shell have the same diameter and as a result a uniform appearance is produced. In an effort to increase the output of brake boosters various methods have been devised to double the size of the housing while maintaining the same effective diameter. U.S. Pat. Nos. 3,146,682; 389,547; 3,517,588; 5,076,142 and 5,323,689 disclose various tandem brake boosters wherein a front shell functions as part of the housing for a plurality of movable wall to produce an output force which is greater than a single brake booster. In this type tandem brake booster the increase in size or length is normally achieved by an increase in the front shell. The increase in physical size in the front shell requires larger stamping equipment and under the hood space than corresponding shells for a single brake booster. These tandem brake boosters function in an adequate manner but at an increase in the weight and may not be acceptable for some customer's applications. In an effort to reduce the weight of a brake booster it has been suggested that a lighter weight or gauge material could be used for the front and rear shells if the forces generated during braking could be directly transmitted from a master cylinder to a wall that separates the engine compartment from the passenger compartment. U.S. Pat. Nos. 4,377,069; 4,783,964, 4,790,235; 5,072,996 and 5,447,030 disclose such structure wherein bolts that connected a master cylinder to a brake booster extend through the interior of a brake booster and are attached to the wall of a vehicle. In the type of structure the movable wall, which is sealed with respect to the bolts, most often slides on the bolts to create a desired braking force. Unfortunately, the sliding surface on the bolts and the cross-sectional diameter for carrying the forces do not provide a resulting brake booster with optimal non-frictional resistance, sealing capability or strength requirements. In an effort to separate the responsibility for these components, brake boosters have been manufactured with tubes therein to provide uniform sliding surfaces for movement of the wall while bolts are sized for the desired strength needed to resist deflection. The bolts being installed by an end user to attach the brake booster to a wall of a vehicle. Recently some end users have decided that it is desirable that manufacturers provide a complete brake booster with all components attached thereto for installation on the wall of a vehicle.
SUMMARY OF THE INVENTION
In an effort to provide a brake booster of simple structure that would meet current customer desires and functional specifications, I have invented a brake booster having a front shell joined to a rear shell with the interior separated by a wall to at least define a first front chamber and a first rear chamber. The brake booster includes a reinforcement plate located adjacent an end face of the front shell which has a plurality of studs for attaching a master cylinder to the front shell. First and second tubes which extend through the wall each have having a first end sealed with respect to the front shell and a second end sealed with respect to the rear shell. A fastener arrangement extends through the first and second tubes for attaching the brake booster to a wall of a vehicle. The fastener arrangement is characterized by first bushing members that are located between the front shell and reinforcing plate and by second bushing members which are secured to the rear shell. The first bushing members each retained in the reinforcing plate that have a first cylindrical body with a stepped bore defined by a first diameter separated from a second diameter by a first shoulder. The first end of each of the first and second tubes is correspondingly located in the second diameter of the first cylindrical members. The first diameter of each first cylindrical body has first threads thereon. The fastener arrangement further includes a first bolt and a second bolt each of which has a stem with a head on a first end and a second end. The stem of the first and second bolts each have second threads thereon adjacent the head and third threads thereon adjacent the second end. The third threads being smaller than the second threads such that the third threads on each stem correspondingly pass through the first threads on the first and second cylindrical members. The second threads of each stem correspondingly engage the first threads on each first cylindrical member to join the first and second bolts to the first and second cylindrical members and position the third threads outside of the rear shell. The brake booster with first and second bolts secured thereto is ready for installation on the wall of a vehicle by an end user by aligning the second ends with corresponding openings in the wall and attaching a nut to the third threads.
An advantage of the present invention resides in the permanent attachment of first and second bolts to corresponding bushings connected to a reinforcing plate which carries studs for a master cylinder to transmit forces to a wall of a vehicle.
A further advantage of this invention is to provide a brake booster with a force transmission path from a master cylinder to a wall in a vehicle by mounting studs for the master cylinder, a reinforcing plate which carries the studs, first and second bushings retained by the reinforcing plate, and first and second bolts correspondingly secured to the bushings and the wall.


REFERENCES:
patent: 4339921 (1982-07-01), Schanz
patent: 5410880 (1995-05-01), Schluter
patent: 5447030 (1995-09-01), Wang et al.
patent: 5487327 (1996-01-01), Schluter et al.
patent: 6050174 (2000-04-01), Schonlau et al.

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