Control system for fluid cylinder

Claim 2

A hydraulic control system for a power cylinder having a piston reciprocating therein comprising: a source of fluid under pressure; a reservoir; conduit means connecting opposite ends of said cylinder to said source and reservoir; a control valve in said conduit means, said control valve having two positions for connecting said source to respective ends of said cylinder while connecting the opposite end to said reservoir; and control means for reversing the position of said valve when said piston reaches one end of said cylinder, the improvement of said control means including: a switch cooperating with said valve; an actuator rod cooperating with said switch, said one end of said cylinder having an opening slidably supporting said actuator rod with an end of said actuator rod disposed in the path of said piston; first means cooperating with said actuator rod and said opening to define a chamber in communication with the interior of said cylinder, said actuator rod having a surface exposed to the pressure in said chamber which is opposed to the surface of said end of said rod and has an area greater than the area of the surface of said end so that said actuator rod is maintained in a first position by the pressure of fluid in said cylinder and is moved to a second position when said piston approaches said one end of said cylinder to actuate said switch and reverse the position of said valve.

Claim 3

A hydraulic control system as defined in claim 1, in which said first means includes an element received in said opening and having a bore extending axially of said opening and receiving said actuator rod, said bore having an enlarged portion defining a portion of said chamber and in which said actuator rod has an enlarged portion slidable in said enlarged portion of said bore to define another portion of said chamber.

Claim 4

A hydraulic control system as defined in claim 2, in which one end of said enlargEd bore is in communication with said chamber and further including vent means placing the opposite end of the enlarged bore in communication with the atmosphere.

Claim 5

A hydraulic control system as defined in claim 2, in which said element has an external threaded portion and said opening has a cooperating threaded portion and in which the communication between the interior of the cylinder and said bore includes means defining a narrow slot in the cooperating threaded portions.

Claim 6

A hydraulic control system for a double-acting reciprocating pump having a pair of power cylinders each having a piston reciprocating therein, comprising a source under pressure; a reservoir; valve means; and conduit means connecting one end of each said cylinder, said reservoir and said source to said valve means and interconnecting the opposite ends of said cylinders, said valve means having first and second positions respectively connecting one of said cylinders to said source and the other of said cylinders to said reservoir; and reversing means for moving said valve means between said positions, said reversing means including switch means for moving said valve between said positions and actuating means for each cylinder, the improvement of each of said actuating means comprising an actuator rod with the associated cylinder having an opening in one end thereof slidably receiving said rod, said rod having an end exposed in said cylinder and located in the path of movement of said piston, said actuator rod cooperating with said one end of said cylinder to define a chamber in communication with the associated cylinder, said actuator rod having a surface exposed to the pressure in said chamber which is in opposed relation to the surface on said end of said rod with said surface in said chamber having an area greater than the surface of said end; and linkage means between said rod and said switch means so that movement of the pistons in the cylinders towards said one end will move said actuator rod to actuate said switch means and reverse the position of said valve means.

Claim 7

A hydraulic control system for a double-acting reciprocating pump having a pair of power cylinders each having a piston reciprocating therein, comprising a source under pressure; a reservoir; valve means; and conduit means connecting one end of each said cylinder, said reservoir and said source to said valve means and interconnecting the opposite ends of said cylinders, said valve means having first and second positions respectively connecting one of said cylinders to said source and the other of said cylinders to said reservoir; and reversing means for moving said valve means between said positions, said reversing means including switch means for moving said valve between said positions and actuating means for each cylinder, the improvement of each of said actuating means comprising an actuator rod with the associated cylinder having an opening in one end thereof slidably receiving said rod, said rod having an end exposed in said cylinder and located in the path of movement of said piston, said actuator rod cooperating with said one end of said cylinder to define a chamber in communication with the associated cylinder, said actuator rod having a surface exposed to the pressure in said chamber which is in opposed relation to the surface on said end of said rod with said surface in said chamber having an area greater than the surface of said end; and linkage means between said rod and said switch means so that movement of the pistons in the cylinders towards said one end will move said actuator rod to actuate said switch means and reverse the position of said valve means.