Power brake mechanism

Claim 2

A two-stage power brake mechanism comprising, in combination, a pressure-responsive movable wall, encapsulated valve means including a hub member movable with said wall, said valve means controlling the pressure differential on opposite sides of said wall, actuating means operable to effect movement of said valve means in response to manual effort, an output member mounted for axial movement relative to said hub member, reaction means including a pair of rectangular levers mounted for pivotal movement in said hub member, the innermost ends only of said levers being movable into engagement with said actuating means for resisting movement of the actuating means in a substantially direct and uniform ratio to the force developed by said wall, a bridge member disposed adjacent said levers and engaging said output member, said bridge member engaging each of said levers intermediate the ends thereof, and pre-loaded metallic spring means having a relatively low spring rate disposed between and engaging said levers and said hub member and biasing said levers in a direction away from said actuating means and toward said bridge member, said spring means being effective to resist movement of said levers during the initial increments of movement of said wall.

Claim 3

In a power brake mechanism, the combination including a housing and a pressure-responsive movable wall forming therewith chambers on opposite sides of said wall, control means controlling the pressure differential on opposite sides of said wall, said control means including a hub member supported by said wall and by said housing and movable with said wall, said hub member having an internal annular first valve seat, a manually movable actuating member slidably supported in said hub member in radially inwardly spaced relationship with respect to said first valve seat, said actuating member having a second valve seat thereon movable in an axial direction relative to said first valve seat, a resilient valve element carried by said hub member, said valve element having an inner annular portion adapted to engage selectively said first and second valve seats, said valve element normally being engaged with said second valve seat to define a closed condition of said control means, said valve member engaging said first valve seat upon axial movement of said actuating member and disengaging from said second valve seat to define an open condition of said control means, an output member mounted for axial movement relative to said hub member, reaction means including a pair of rectangular levers mounted for pivotal movement in said hub member, the innermost ends only of said levers being movable into engagement with said actuating member for resisting movement of the actuating member in a substantially direct and uniform ratio to the force developed by said wall, a bridge member disposed adjacent said levers and engaging said output member, said bridge member engaging each of said levers intermediate the ends thereof, and pre-loaded metallic spring means having a relatively low spring rate disposed between and engaging said levers and said hub member and biasing said levers in a direction away from said actuating member and toward said bridge member, said spring means being effective to resist movement of said levers during the initial increments of movement of said wall.

Claim 4

In a power brake mechanism, the combination including a housing and a pressure-responsive movable wall forming therewith chambers on opposite sides of said wall, control means controlling the pressure differential on opposite sides of said wall, said control means including a hub member supported by said wall and by said housing and movable with said wall, said hub member having an internal annular first valve seat, a manually movable actuating member slidably supported in said hub member in radially inwardly spaced relationship with respect to said first valve seat, said actuating member having a second valve seat thereon movable in an axial direction relative to said first valve seat, a resilient valve element carried by said hub member, said valve element having an inner annular portion adapted to engage selectively said first and second valve seats, said valve element normally being engaged with said second valve seat to define a closed condition of said control means, said valve member engaging said first valve seat upon axial movement of said actuating member and disengaging from said second valve seat to define an open condition of said control means, an output member mounted for axial movement relative to said hub member, reaction means including a pair of rectangular levers mounted for pivotal movement in said hub member, the innermost ends only of said levers being movable into engagement with said actuating member for resisting movement of the actuating member in a substantially direct and uniform ratio to the force developed by said wall, a bridge member disposed adjacent said levers and engaging said output member, said bridge member engaging each of said levers intermediate the ends thereof, and pre-loaded metallic spring means having a relatively low spring rate disposed between and engaging said levers and said hub member and biasing said levers in a direction away from said actuating member and toward said bridge member, said spring means being effective to resist movement of said levers during the initial increments of movement of said wall.

Claim 5

In a power brake mechanism, the combination including a housing having a movable wall therein forming a low pressure chamber in constant communication with a source of vacuum and a variable pressure chamber on the opposite side of said wall, a source of atmospheric pressure, encapsulated valve means including a hub member movable with said wall, said valve means controlling communication between said chambers and between said atmospheric source and said variable pressure chamber, said valve means including a first valve seat movable with said wall and a second valve seat manually movable with respect to said wall, a flexible resilient valve element movable with and relative to said wall, said valve element normally being engaged with said second valve seat and disengaged from said first valve seat to maintain said chambers in communication with each other and isolated from said atmospheric source, said second valve seat being manually movable in a first stage permitting said valve element to engage said first valve seat to isolate said chambers from each other, said second valve seat being manually movable in a second stage out of engagement with said valve element to admit atmospheric pressure to said variable pressure chamber to effect movement of said wall, an output member mounted for axial movement relative to said hub member, reaction means including a pair of rectangular levers mounted for pivotal movement in said hub member, the innermost ends only of said levers being movable into engagement with said valve means for resisting movement of said second valve seat in a substantially direct and uniform ratio to the force developed by said wall, a bridge member disposed adjacent said levers and engaging said output member, said bridge member engaging each of said levers intermediate the ends thereof, and pre-loaded metallic spring means having a relatively low spring rate disposed between and engaging said levers and said hub member and biasing said levers in a direction away from said valve means and toward said bridge member, said spring means being effective to resist movement of said levers during the initial increments of movement of said wall.

Claim 6

In a power brake mechanism, the combination including a housing having a movable wall therein forming a low pressure chamber in constant communication with a source of vacuum and a variable pressure chamber on the opposite side of said wall, a source of atmospheric pressure, encapsulated valve means including a hub member movable with said wall, said valve means controlling communication between said chambers and between said atmospheric source and said variable pressure chamber, said valve means including a first valve seat movable with said wall and a second valve seat manually movable with respect to said wall, a flexible resilient valve element movable with and relative to said wall, said valve element normally being engaged with said second valve seat and disengaged from said first valve seat to maintain said chambers in communication with each other and isolated from said atmospheric source, said second valve seat being manually movable in a first stage permitting said valve element to engage said first valve seat to isolate said chambers from each other, said second valve seat being manually movable in a second stage out of engagement with said valve element to admit atmospheric pressure to said variable pressure chamber to effect movement of said wall, an output member mounted for axial movement relative to said hub member, reaction means including a pair of rectangular levers mounted for pivotal movement in said hub member, the innermost ends only of said levers being movable into engagement with said valve means for resisting movement of said second valve seat in a substantially direct and uniform ratio to the force developed by said wall, a bridge member disposed adjacent said levers and engaging said output member, said bridge member engaging each of said levers intermediate the ends thereof, and pre-loaded metallic spring means having a relatively low spring rate disposed between and engaging said levers and said hub member and biasing said levers in a direction away from said valve means and toward said bridge member, said spring means being effective to resist movement of said levers during the initial increments of movement of said wall.