Sliding ring non-return valve

A sliding ring non-return valve for use with a driving screw in a barrel, the driving screw defining a material feed path, the non-return valve comprising:

• a frame slidably disposed within the barrel, the frame having a distal end and a proximal end, the proximal end attached to the driving screw;
• a flange surface formed on the frame between the proximal end and the driving screw, the flange surface having an outer diameter less than the inside diameter of the barrel and defining a radial seal surface;
• a plurality of grooves along an outer surface of the frame, the grooves being in communication with the material feed path;
• an annular inlet groove formed in and extending at least partially around the circumference of the outer surface of the frame and defining a pair of opposing sidewalls spaced apart a selected width, the inlet groove intersecting the grooves;
• a retaining cap at the distal end of the frame;
• a ring member, longer than the width of the annular inlet groove and slidable on the frame between the retaining cap and the flange, the ring being slidable between a first position, adjacent the retaining cap, in which the annular inlet groove is unobstructed and a second position, adjacent the radial sealing surface on the flange, in which the inlet groove is obstructed.

A sliding ring non-return valve for use in an injection molding apparatus, which includes a screw rotatable about an axis and reciprocal along the axis, to discharge a working fluid at a discharge end thereof, the non-return valve comprising:

• a generally cylindrical frame fitting closely but slidably within a barrel, the frame having an upstream and a downstream end, the upstream end coupled to the screw and having one or more passages extending at least partially through the frame, the passages being in fluid communication with an accumulation volume in the barrel downstream from the valve;
• an annular inlet groove formed in the frame at the upstream end and intersecting the passages, the annular inlet groove extending about at least a part of the circumference of the frame and defining a pair of spaced-apart sidewalls;
• a flange formed on the upstream end of the frame, the flange including a radial seal surface;
• a ring, having a length longer than the spaced-apart sidewalls and being coaxial with and slidable on the frame to close the annular inlet groove and the passages and abut with the radial seal surface on the flange when the ring is in an upstream direction and to allow fluid flow in the passages when the ring is in a downstream position;
• and
• a retaining means secured around the frame at its downstream end to limit the downstream travel of the ring.

A sliding ring non-return valve comprising:

• a frame having a circumference and an outer surface and distal and proximal ends;
• at least one fluid passage extending at least partially through the frame and defining an inlet at its proximal end and an outlet at its distal end;
• an inlet groove extending about the circumference of the frame and having a pair of opposing sidewalls defining a groove width, at least one of which intersects the inlet of the fluid passage;
• a flange extending radially from the proximal end of the frame, the flange defining a radial seal surface;
• a retaining cap secured to the distal end of the frame;
• and
• a ring member, longer than the width of the inlet groove and movable between the retaining cap and the flange, the ring being movable between a first position in which the inlet groove is uncovered and a second position in which the inlet groove is covered and the ring abuts and seals against the radial seal surface on the flange.

A non-return valve for use with a flighted screw rotating and reciprocating within the barrel of an injection molding apparatus, the non-return valve comprising:

• a generally cylindrical frame coupled to the screw at one end and having a generally conical downstream end;
• a flange formed on the frame proximal the end coupled to the screw;
• a retaining member formed on the frame proximal the downstream end of the frame;
• an annular groove formed in the surface of the frame proximal the flange and extending about the circumference of the frame, the annular inlet groove defining a pair of opposing walls spaced apart a selected width;
• a plurality of grooves formed in the surface of the frame intersecting the annular groove and extending to the downstream end of the frame;
• and
• a ring disposed about the frame and movable between the flange and retaining member responsive to fluid pressure, the ring being longer than the width of the groove, to selectively obstruct the annular groove and at least partially prevent fluid flow through the grooves.