Injection unit for an injection molding machine

An injection unit, comprising:

• a) a hollow cylindrical casing rotatably supported by a housing, the cylindrical casing having an axis and a front end and a back end spaced apart along the axis;
• b) a piston in the cylindrical casing, the piston axially slidable relative to the cylindrical casing along the axis between advanced and retracted positions;
• and
• c) a cylinder cap having a bearing face generally closing off the back end of the hollow cylindrical casing and facing the piston, the hollow cylindrical casing having a first pressure chamber between the piston and the bearing face, the bearing face including at least a stationary face portion affixed to the housing and against which fluid in the first pressure chamber bears, the hollow cylindrical casing rotatable about the axis relative to the housing and the stationary face portion of the bearing face.

An actuator for an injection unit of an injection molding machine, comprising:

• a) a cylinder including a hollow cylindrical casing having a cylinder axis, and a cylinder cap generally closing off one end of the cylindrical casing;
• b) a piston translatable within the cylinder along the cylinder axis between advanced and retracted positions, at least the piston being rotatable about the cylinder axis;
• c) the cylinder comprising a first pressure chamber on a first side of the piston facing the cylinder cap for urging the piston in a first direction when pressurized, and the cylinder comprising a second pressure chamber on a second side of the piston opposite the first side for urging the piston in a second direction when pressurized, the second direction opposite the first direction;
• and
• d) a fluid conduit extending between the cylinder cap and the piston and generally through the first pressure chamber for fluid communication with the second pressure chamber,
• wherein the fluid conduit comprises a generally cylindrical tube coaxial with the cylinder axis,
• and wherein the cylindrical casing is rotationally locked with the piston and rotates about the cylinder axis with the piston.

An injection unit for an injection molding machine, comprising:

• a) a hollow cylindrical casing rotatably supported by a housing, the cylindrical casing having an axis and a front end and a back end spaced apart along the axis;
• b) a piston in the cylindrical casing, the piston axially slidable relative to the cylindrical casing along the axis between advanced and retracted positions, and the piston rotationally locked with the cylindrical casing to rotate therewith;
• and
• c) rotor components affixed to the cylindrical casing so that the cylindrical casing is the rotor of a hollow electric motor.