Injection molding three-way shut off valve

An apparatus for controlling a flow of molten material between an injection unit and a runner system, the apparatus comprising:

• a valve housing;
• and
• a valve stem configured to move within said valve housing between a molten material flow position, a molten material block position, and a molten material purge position, said valve stem being configured so that the valve stem is moved to the molten material purge position without disconnecting the injection unit from the runner system
• wherein:
• said valve stem has a flow-through channel and a purge channel, and further comprising movement structure configured to move the valve stem between the molten material flow position, the molten material block position, and the molten material purge position,
• said movement structure comprises:
• a first piston configured to move said valve stem between the molten material flow position, the molten material block position, and the molten material purge position;
• a controller configured to control movement of said first piston;
• and
• a second piston configured to reduce the movement of said first piston in the molten material flow position and the molten material block position, and wherein said controller is configured to control the movement of said second piston.

The apparatus for controlling a flow of a melt between (i) an injection unit and a runner system the apparatus comprising:

• a block configured to be disposed between the injection unit and the runner system, and having a melt channel therein;
• a valve piece disposed in said block and configured to be movable between a melt flow position, a melt block position, and a melt purge position, said valve piece having a flow channel configured to permit the melt to flow from the block melt channel of the block to the runner system, said valve piece having a purge channel configured to permit the melt to flow from the melt channel of the block to an outside of said block, without disconnecting said block from any one of the injection unit and the runner system;
• and
• movement structure configured to move the valve piece between the melt flow piston, the melt block position, and the melt purge position, said movement structure comprising:
• a first piston configured to move said valve piece between the melt flow position, the melt block position, and the melt purge position;
• a second piston configured to reduce movement of said first piston in the melt flow position and the melt block position;
• and
• a controller configured to control the movement of said first piston and said second piston.