Apparatus for regulating the speed of and the pressure of fluid upon the ram in the injection assembly of an injection molding machine

Claim 1

Apparatus for regulating the speed of and the fluid pressure acting upon the ram in the cylinder of an injection molding machine for thermoplastic material wherein the injection cylinder has a chamber for reception of pressurized fluid, comprising a two-way valve including a housing having a bore including a smaller diameter first portion, a larger diameter second portion, and a compartment between said portions, an inlet communicating with said first of said bore portions and an outlet communicating with said compartment, said valve including further a valve member movable in said housing between at least one first position in which said inlet is sealed from said outlet and a plurality of second positions in each of which said valve member allows said fluid to flow from said inlet to said outlet but at a different rate, said valve member including interconnected first and second sections respectively slidable in said first and second portions of said bore and respectively defining with said bore portions first and second chambers to opposite sides of said valve member, said housing further having a conical seat located in said compartment adjacent said first portion of said bore, said second section of said valve member which is slidable in said second portion of said bore having a conical sealing portion which engages said seat in said first position of said valve member and said sealing portion including a flow regulating device comprising a cylindrical element which is sealingly received in said first portion of said bore in said first position of said valve member, and a conical element rigid with said cylindrical element and defining with said seat a clearance whose size varies in response to movement of said valve member between said plurality of positions; a conduit connecting said outlet with the chamber of said injection cylinder; a source of pressurized hydraulic fluid connected to said inlet; means for selectively feeding and discharging pressurized fluid from said source into and out from said chambers for moving said valve member between said positions thereof; and stop means extending into said second chamber and being movable axially of said housing to thus select the second position of said valve member.