Hydraulic power brake booster

Claim 2

In a fluid operated boost mechanism for a vehicle, the combination of: housing means provided with cylinder means therein; inlet and outlet ports in said housing in communication with said cylinder means; piston means reciprocable in said cylinder means; said piston means and said cylinder means together forming two chambers, located at the respective ends of said piston means; valve means located concentrically of said piston means for regulating fluid flow between said ports and to said two chambers; and operator-operated means including valve actuating means for actuating said valve means to cause movement of said piston means by fluid under pressure acting thereon and further including means for actuating said piston means solely by manual effort; said operator-operated means also including lever means interconnecting said valve actuating means and said means for manually actuating said piston for establishing a low lever ratio for fluid actuation of said piston and a higher lever ratio for manual actuation of said piston; said valve means having adjusting means for trimming the valve so that when the operator-operated means is released fluid pressure is greater in one of said two chambers than in the other to thereby assist in returning said piston means to one end of said cylinder, said valve means is an open center valve equipped with a by-pass orifice which supplies a regulated but continuous flow of fluid between the inlet and outlet ports.

Claim 3

The combination as defined in claim 1, wherein said adjustment comprises a valve trim screw member coaxially carried in said piston means and said valve means, said screw having one end engaging said piston means and its other end threaded into the spool of said valve means, and a spring interposed between said piston means and said spool for retaining said spool in its adjusted position in said valve means and for maintaining a space between said piston means and that end of said spool adjacent thereto to permit relative movement therebetween.

Claim 4

The combination as defined in claim 2, wherein said piston means forms an abutment for engagement by said adjacent end of said spool when the latter moves into said space upon manual actuation of said piston means.

Claim 5

In a fluid operated boost mechanism for a vehicle, the combination of: housing means provided with cylinder means therein; inlet and outlet ports in said housing in communication with said cylinder means; piston means reciprocable in said cylinder means; said piston means and said cylinder means together forming two chambers, located at the respective ends of said piston means; valve means located concentrically of said piston means for regulating fluid flow between said ports and to said two chambers; and operator-operated means iNcluding valve actuating means for actuating said valve means to cause movement of said piston means by fluid under pressure acting thereon and further including means for actuating said piston means solely by manual effort; said operator-operated means also including lever means interconnecting said valve actuating means and said means for manually actuating said piston for establishing a low lever ratio for fluid actuation of said piston and a higher lever ratio for manual actuation of said piston; said lever being pivotally fixed at one end and provided with a foot engaging portion at its free end; said valve actuating means including a first linkage connected to said valve means and to said lever; said means for manually actuating said piston including a second linkage connected to said valve means and to said lever at a point closer to the fixed pivot than said first linkage to thereby establish a mechanical advantage over said first linkage, said first linkage including a hydraulic connection.

Claim 6

In a fluid operated boost mechanism for a vehicle, the combination of: housing means provided with cylinder means therein; inlet and outlet ports in said housing in communication with said cylinder means; piston means reciprocable in said cylinder means; said piston means and said cylinder means together forming two chambers, located at the respective ends of said piston means; valve means located concentrically of said piston means for regulating fluid flow between said ports and to said two chambers; and operator-operated means iNcluding valve actuating means for actuating said valve means to cause movement of said piston means by fluid under pressure acting thereon and further including means for actuating said piston means solely by manual effort; said operator-operated means also including lever means interconnecting said valve actuating means and said means for manually actuating said piston for establishing a low lever ratio for fluid actuation of said piston and a higher lever ratio for manual actuation of said piston; said lever being pivotally fixed at one end and provided with a foot engaging portion at its free end; said valve actuating means including a first linkage connected to said valve means and to said lever; said means for manually actuating said piston including a second linkage connected to said valve means and to said lever at a point closer to the fixed pivot than said first linkage to thereby establish a mechanical advantage over said first linkage, said first linkage including a hydraulic connection.

Claim 7

In a fluid operated boost mechanism for a vehicle, the combination of: housing means provided with cylinder means therein; inlet and outlet ports in said housing in communication with said cylinder means; piston means reciprocable in said cylinder means; said piston means and said cylinder means together forming two chambers, located at the respective ends of said piston means; valve means located concentrically of said piston means for regulating fluid flow between said ports and to said two chambers; and operator-operated means including valve actuating means for actuating said valve means to cause movement of said piston means by fluid under pressure acting thereon and further including means for actuating said piston means solely by manual effort; said operator-operated means also including lever means interconnecting said valve actuating means and said means for manually actuating said piston for establishing a low lever ratio for fluid actuation of said piston and a higher lever ratio for manual actuation of said piston; said means for actuating said valve means including a fluid connection and said means for actuating said piston means solely by manual effort comprises a mechanical connection.

Claim 8

In a fluid operated boost mechanism for a vehicle, the combination of: housing means provided with cylinder means therein; inlet and outlet ports in said housing in communication with said cylinder means; piston means reciprocable in said cylinder means; said piston means and said cylinder means together forming two chambers, located at the respective ends of said piston means; valve means located concentrically of said piston means for regulating fluid flow between said ports and to said two chambers; and operator-operated means including valve actuating means for actuating said valve means to cause movement of said piston means by fluid under pressure acting thereon and further including means for actuating said piston means solely by manual effort; said operator-operated means also including lever means interconnecting said valve actuating means and said means for manually actuating said piston for establishing a low lever ratio for fluid actuation of said piston and a higher lever ratio for manual actuation of said piston; said means for actuating said valve means including a fluid connection and said means for actuating said piston means solely by manual effort comprises a mechanical connection.

Claim 9

In a fluid pressure system for a vehicle having an open center valve steering gear in fluid flow communication with a source of fluid via a boost mechanism, said boost mechanism comprising: housing means including cylinder means therein; inlet and exhaust ports in said housing communicating with said cylinder means and providing for the fluid communication with said source and said open center valve steering gear; piston means reciprocable in said cylinder means; said piston means and said cylinder means together forming two chambers, located at the respective ends of said piston means; valve means concentrically located with respect to said piston means for controlling fluid flow between said ports and to said two chambers; and operator-operated means for actuating said valve means from a released position to an applied position to cause movement of said piston means under the influence of fluid pressure and further including means for actuating said piston means solely through manual effort; said valve means being provided with means for trimming said valve so that the fluid pressure differential acting in said chambers is such as to assist in returning said piston means to its unapplied position upon return of the valve means to its released position.

Claim 10

In a fluid pressure system for a vehicle having an open center valve steering gear in fluid flow communication with a source of fluid via a boost mechanism, said boost mechanism comprising: housing means including cylinder means therein; inlet and exhaust ports in said housing communicating with said cylinder means and providing for the fluid communication with said source and said open center valve steering gear; piston means reciprocable in said cylinder means; said piston means and said cylinder means together forming two chambers, located at the respective ends of said piston means; valve means concentrically located with respect to said piston means for controlling fluid flow between said ports and to said two chambers; and operator-operated means for actuating said valve means from a released position to an applied position to cause movement of said piston means under the influence of fluid pressure and further including means for actuating said piston means solely through manual effort; said valve means being provided with means for trimming said valve so that the fluid pressure differential acting in said chambers is such as to assist in returning said piston means to its unapplied position upon return of the valve means to its released position.

Claim 11

The combination as defined in claim 6, wherein said valve means includes a by-pass orifice which supplies a continuous but regulated flow of fluid to said steering gear valve.

Claim 12

The combination as defined in claim 6, wherein relief valve means is connected between said ports to insure fluid pressure sharing between said steering gear and said boost mechanism.

Claim 13

In a hydraulic power brake boost mechanism haviNg piston means to be controlled by valve means of an open center type positioned coaxially of said piston means and movable from a released position to an applied position to actuate said brake boost mechanism, and a dual ratio mechanism connected to both said means for establishing a low lever ratio for hydraulic actuation of said piston means and higher lever ratio for solely manual actuation of said piston means, an improvement for adjusting said valve means so that upon movement of the valve means to its released position, a pressure differential acts across said piston means to assist in returning said piston means, said improvement comprising: and means connecting said piston means with said valve means to trim the latter to create a higher back pressure on one end of said piston means than at the other end, to thereby return said piston means as aforesaid.

Claim 14

In a hydraulic power brake boost mechanism haviNg piston means to be controlled by valve means of an open center type positioned coaxially of said piston means and movable from a released position to an applied position to actuate said brake boost mechanism, and a dual ratio mechanism connected to both said means for establishing a low lever ratio for hydraulic actuation of said piston means and higher lever ratio for solely manual actuation of said piston means, an improvement for adjusting said valve means so that upon movement of the valve means to its released position, a pressure differential acts across said piston means to assist in returning said piston means, said improvement comprising: and means connecting said piston means with said valve means to trim the latter to create a higher back pressure on one end of said piston means than at the other end, to thereby return said piston means as aforesaid.