Tandem type vacuum booster

A tandem type vacuum booster comprising:

• a booster shell having a front end;
• a front booster piston reciprocating back and forth in said booster shell;
• a piston boss for engaging said front booster piston;
• a coupling cylinder extending from an inner peripheral edge of said front booster piston and positioned in a front end portion of said piston boss, said coupling cylinder including a bottom plate for coupling with said piston boss;
• a return coil spring elastically set between a front end wall of said booster shell and said piston boss, for urging said piston boss in a direction away from said front end of said booster shell;
• and
• a reinforcing cylinder positioned in said coupling cylinder, said coupling cylinder integrally formed with said front booster piston,
• wherein said reinforcing cylinder includes an inward flange at a front end thereof, said inward flange being biased by a rear end of said return coil spring for holding said reinforcing cylinder on said bottom plate of said coupling cylinder at a predetermined contact position,
• wherein said booster further comprises a plurality of ribs positioned on an inner cylindrical surface of said reinforcing cylinder, wherein said ribs extend radially from said inward flange,
• said ribs being coupled to a rear surface of said inward flange.

A tandem type vacuum booster comprising:

• a booster shell having a front end;
• a front booster piston reciprocating back and forth in said booster shell;
• a piston boss for engaging said front booster piston;
• a coupling cylinder extending from an inner peripheral edge of said front booster piston and positioned in a front end portion of said piston boss, said coupling cylinder including a bottom plate for coupling with said piston boss;
• a return coil spring elastically set between a front end wall of said booster shell and said piston boss, for urging said piston boss in a direction away from said front end of said booster shell;
• and
• a reinforcing cylinder positioned in said coupling cylinder, said coupling cylinder integrally formed with said front booster piston,
• wherein said reinforcing cylinder includes an inward flange at a front end thereof, said inward flange being biased by a rear end of said return coil spring for holding said reinforcing cylinder on said bottom plate of said coupling cylinder at a predetermined contact position,
• wherein said inward flange includes an annular protrusion, said annular protrusion for engaging the rear end of said return coil spring.

A tandem type vacuum booster comprising:

• a booster shell having a front end;
• a front booster piston reciprocating back and forth in said booster shell;
• a piston boss for engaging said front booster piston;
• a coupling cylinder extending from an inner peripheral edge of said front booster piston and positioned in a front end portion of said piston boss, said coupling cylinder including a bottom plate for coupling with said piston boss;
• a return coil spring elastically set between a front end wall of said booster shell and said piston boss, for urging said piston boss in a direction away from said front end of said booster shell;
• and
• a reinforcing cylinder positioned in said coupling cylinder, said coupling cylinder integrally formed with said front booster piston,
• wherein said reinforcing cylinder includes an inward flange at a front end thereof, said inward flange being biased by a rear end of said return coil spring for holding said reinforcing cylinder on said bottom plate of said coupling cylinder at a predetermined contact position,
• said booster further comprises an annular protrusion comprising a prolongation of the front end of said reinforcing cylinder, said annular protrusion being rigidly attached to the rear end of said return coil spring on an inner cylindrical surface thereof.

A tandem type vacuum booster comprising:

• a booster shell having a front end;
• a front booster piston reciprocating back and forth in said booster shell;
• a piston boss for engaging said front booster piston;
• a coupling cylinder extending from an inner peripheral edge of said front booster piston and positioned in a front end portion of said piston boss, said coupling cylinder including a bottom plate for coupling with said piston boss;
• a return coil spring elastically set between a front end wall of said booster shell and said piston boss, for urging said piston boss in a direction away from said front end of said booster shell;
• and
• a reinforcing cylinder positioned in said coupling cylinder, said coupling cylinder integrally formed with said front booster piston,
• wherein said reinforcing cylinder includes an inward flange at a front end thereof, said inward flange being biased by a rear end of said return coil spring for holding said reinforcing cylinder on said bottom plate of said coupling cylinder at a predetermined contact position,
• said booster further comprising an output rod coupled to said piston boss, said output rod protruding from said piston boss in a direction toward said front end,
• wherein said inward flange includes an inner peripheral surface for supporting said output rod at a middle portion of said output rod.

A vacuum booster comprising:

• a booster shell having a front end;
• a front booster piston reciprocating back and forth in said booster shell;
• a piston boss coupled to said front booster piston;
• a first cylinder extending from an edge of said front booster piston positioned in a front end portion of said piston boss, said first cylinder including a plate for coupling with said piston boss;
• means for connecting said piston boss to said plate;
• a return coil spring for urging said piston boss in a direction away from said front end;
• and
• a second cylinder positioned in said first cylinder,
• wherein said second cylinder includes an inward flange at a front end thereof for reinforcing said second cylinder and for holding said return coil spring, said second cylinder being positioned so as to surround said connecting means;
• and
• second cylinder being held in said first cylinder solely by said return coil spring.

A vacuum booster comprising:

• a booster shell having a front end;
• a front booster piston reciprocating back and forth in said booster shell;
• a piston boss coupled to said front booster piston;
• a first cylinder extending from an edge of said front booster piston positioned in a front end portion of said piston boss, said first cylinder including a plate for coupling with said piston boss;
• means for connecting said piston boss to said plate;
• a spring for urging said piston boss in a direction away from said front end;
• a second cylinder positioned in said first cylinder, wherein said second cylinder is positioned so as to surround said connecting means;
• and
• retaining means for retaining said second cylinder in a predetermined position on said plate,
• wherein said retaining means is separately formed from said connecting means,
• said second cylinder includes an inward flange at a front end thereof,
• said retaining means comprises a rear end of said spring being in contact with said inward flange and said rear end of said spring urging said inward flange against said plate,
• a plurality of ribs positioned on an inner cylindrical surface of said second cylinder, wherein said ribs extend radially from said inward flange.

A vacuum booster comprising:

• a booster shell having a front end;
• a front booster piston reciprocating back and forth in said booster shell;
• a piston boss coupled to said front booster piston;
• a first cylinder extending from an edge of said front booster piston positioned in a front end portion of said piston boss, said first cylinder including a plate for coupling with said piston boss;
• means for connecting said piston boss to said plate;
• a spring for urging said piston boss in a direction away from said front end;
• a second cylinder positioned in said first cylinder, wherein said second cylinder is positioned so as to surround said connecting means;
• and
• an annular protrusion including a prolongation of the front end of said second cylinder.