Reciprocating pump

Claim 2

A reciprocating pump comprising a housing containing a cylinder including a rod end and a head end, a piston reciprocable within said cylinder, a rod extending from said piston through the rod end of said cylinder, valve means for supplying pressure to the head end of said cylinder when said piston is adjacent said head end to cause movement of said piston toward the rod end and for venting said head end when said piston is adjacent the rod end of said cylinder, and means for returning said piston toward said head end of said cylinder when said head end is vented as aforesaid, said valve means being contained in a valve bore in said piston, and a porting tube extending from the head end of said cylinder into an opening in said piston, said porting tube and piston having communicating passages therein for supplying pressure through said porting tube to said valve bore.

Claim 3

The pump of claim 1 further comprising vent means for continuously venting said rod end of said cylinder.

Claim 4

The pump of claim 1 wherein said means for returning said piston toward said head end of said cylinder comprises a spring acting on the outer end of said piston rod.

Claim 5

The pump of claim 1 wherein said means for returning said piston toward said head end of said cylinder comprises the hydraulic fluid to be pumped which is maintained under low pressure.

Claim 6

The pump of claim 1 wherein said porting tube has a pair of longitudinally spaced external seals in sealing engagement with the wall of said opening in said piston, and an external groove between said seals, said porting tube also having a passage therein extending from the head end of said cylinder to said groove for supplying pressure to said groove, said piston having a first port between said valve bore and opening which provides communication between said groove in said porting tube and said valve bore, a vent passage communicating with said valve bore, and a second port extending from the head end of said piston to said valve bore, said valve means when disposed at one end of aid valve bore providing communication between said second port and said vent passage for venting the head end of said cylinder, and when positioned at the other end of said valve bore establishing communication between said first and second ports for supplying pressure to said head end of said cylinder, and means for moving said valve mans from one end of said valve bore to the other when said piston reaches the ends of its stroke.

Claim 7

The pump of claim 5 wherein said means for moving said valve means as aforesaid comprises a pair of longitudinally spaced trigger ports in said piston connecting said valve bore with said opening for said porting tube said trigger ports being positioned to supply pressure from said external groove in said porting tube to one end of said valve bore when said piston is at the rod end of its stroke for moving said valve means to the other end of said valve bore, and also positioned to vent said one end of said valve bore to the inner end of said opening in said piston when said piston is at the head end of its stroke, a passage in said piston venting The inner end of said opening to the rod end of said cylinder, and means for moving said valve means to said one end of said valve bore upon venting said one end.

Claim 8

The pump of claim 6 wherein said means for moving said valve means to said one end of said valve bore comprises a differential area on said valve means less than the area of said one end of said valve means, and porting in said piston for supplying pressure to said valve bore which acts on said differential area.

Claim 9

The pump of claim 6 wherein said means for moving said valve means to said one end of said valve bore comprises a spring interposed between said valve means and the other end of said valve bore.

Claim 10

A reciprocating pump comprising a housing containing a cylinder including a rod end and a head end, a piston reciprocable within said cylinder, a rod extending from said piston through the rod end of said cylinder, valve means for supplying pressure to the head end of said cylinder when said piston is adjacent said head end to cause movement of said piston toward the rod end and for venting said head end when said piston is adjacent the rod end of said cylinder, and means for returning said piston toward said head end of said cylinder when said head end is vented as aforesaid, said valve means being contained in a valve bore in said piston, and a pair of longitudinally spaced trigger ports in said piston which alternately vent and pressurize one end of said valve bore at opposite ends of the stroke of said piston to cause movement of said valve means for alternately venting and pressurizing the head end of said cylinder.

Claim 11

A reciprocating pump comprising a housing containing a cylinder including a rod end and a head end, a piston reciprocable within said cylinder, a rod extending from said piston through the rod end of said cylinder, valve means for supplying pressure to the head end of said cylinder when said piston is adjacent said head end to cause movement of said piston toward the rod end and for venting said head end when said piston is adjacent the rod end of said cylinder, and means for returning said piston toward said head end of said cylinder when said head end is vented as aforesaid, said valve means being contained in a valve bore in said piston, and a pair of longitudinally spaced trigger ports in said piston which alternately vent and pressurize one end of said valve bore at opposite ends of the stroke of said piston to cause movement of said valve means for alternately venting and pressurizing the head end of said cylinder.

Claim 12

The pump of claim 9 wherein said valve means has a pair of longitudinally spaced seals which isolate said trigger ports from each other for all positions of said valve means, said valve means when in a pressure balanced position with respect to said trigger ports causing venting of the head end of said cylinder to permit movement of said piston toward the head end of said cylinder by the external applied force, the relative spacing between said trigger ports in said valve bore being somewhat greater than the relative spacing between said seals in said valve means, whereby when said piston reaches the head end of said cylinder, pressure is supplied to both of said trigger ports and is permitted to leak past both of said seals to said one end of said valve bore, causing movement of said valve means toward the other end of said valve bore.

Claim 13

The pump of claim 9 wherein said valve means is caused to move to the other end of said valve bore in response to pressure applied to said one end of said valve bore, and means are provided for moving said valve means to said one end of said valve bore upon venting said one end.

Claim 14

The pump of claim 11 wherein said means for moving said valve means to said one end of said valve bore comprises a differential area on said valve means less than the area of said one end of said valve means, and porting in said piston for supplying pressure to said differential area.

Claim 15

The pump of claim 11 wherein said means for moving said valve means to said one end of said valve bore comprises a spring interposed between said valve means and the other end of said valve bore.

Claim 16

A reciprocating pump comprising a housing containing a cylinder including a rod end and a head end, a piston reciprocable within said cylinder, a rod extending from said piston through the rod end of said cylinder, valve means for supplying pressure to the head end of said cylinder when said piston is adjacent said head end to cause movement of said piston toward the rod end and for venting said head end when said piston is adjacent the rod end of said cylinder, and means for returning said piston toward said head end of said cylinder when said head end is vented as aforesaid, said piston containing a first valve bore for receipt of said valve means, and a second valve bore for receipt of a supplemental valve means through which one end of said valve means is alternately prEssurized and vented when said piston reaches the ends of its stroke, the pressurizing of said one end of said first valve bore causing said valve means to move to the other end of said first valve bore for pressurizing the head end of said cylinder, and means for moving said valve means to said one end of said first valve bore for venting the head end of said cylinder upon venting said one end of said first valve bore.

Claim 17

A reciprocating pump comprising a housing containing a cylinder including a rod end and a head end, a piston reciprocable within said cylinder, a rod extending from said piston through the rod end of said cylinder, valve means for supplying pressure to the head end of said cylinder when said piston is adjacent said head end to cause movement of said piston toward the rod end and for venting said head end when said piston is adjacent the rod end of said cylinder, and means for returning said piston toward said head end of said cylinder when said head end is vented as aforesaid, said piston containing a first valve bore for receipt of said valve means, and a second valve bore for receipt of a supplemental valve means through which one end of said valve means is alternately prEssurized and vented when said piston reaches the ends of its stroke, the pressurizing of said one end of said first valve bore causing said valve means to move to the other end of said first valve bore for pressurizing the head end of said cylinder, and means for moving said valve means to said one end of said first valve bore for venting the head end of said cylinder upon venting said one end of said first valve bore.

Claim 18

The pump of claim 14 wherein said last-mentioned means comprises a spring interposed between said valve means and the other end of said first valve bore.

Claim 19

The pump of claim 15 wherein said supplemental valve means is movable by the pressure supplied to said one end of said first valve bore to a position blocking further pressure flow therethrough, and a further spring stronger than the spring acting on said valve means resists such movement of said supplemental valve means until said valve means has moved to a position permitting pressure to be supplied to said one end of said first valve bore through a trigger port in said piston.