Apparatus and method for cooling plastic containers

In a stretch blow molding apparatus having a mold, a blow nozzle for introducing air to inflate a parison within the mold, and a stretch rod reciprocally movable with respect to the blow nozzle for stretching the parison located within the mold during the inflation the parison to form a container, and a cryogenic liquid reservoir, the improvement comprising:

• a cryogenic liquid pulse pump assembly disposed in sealed fluid connection between the reservoir and the stretch rod a cryogenic liquid containing chamber in sealed fluid connection to the reservoir, a variable volume pump situated within the chamber so as to be immersed in the cryogenic liquid, the variable volume pump including an inlet valve that allows a flow of cryogenic liquid from the liquid chamber into the pump cylinder and an outlet conduit in sealed fluid connection to the stretch rod, and a pressure source for applying a pressure to the cryogenic liquid to cause an outflow of cryogenic liquid from the variable volume pump into the outlet conduit;
• and
• control means including a pressure sensor coupled to the outlet conduit and to the pressure source for controlling the pressure of the outflowing cryogenic liquid, a detector adjustably positionable with respect to the variable volume pump for detecting displacement of an element of the pump reflecting the delivery of a preselected volume of cryogenic liquid by the pump.

In a stretch blow molding apparatus having a mold, a blow nozzle for introducing air to inflate a parison within the mold, and a stretch rod reciprocally movable with respect to the blow nozzle for stretching the parison located within the mold during the inflation the parison to form a container, and a cryogenic liquid reservoir, the improvement comprising:

• a cryogenic liquid pulse pump assembly disposed in sealed fluid connection between the reservoir and the stretch rod a cryogenic liquid containing chamber in sealed fluid connection to the reservoir, a variable volume pump situated within the chamber so as to be immersed in the cryogenic liquid, the variable volume pump including an inlet valve that allows a flow of cryogenic liquid from the liquid chamber into the pump cylinder and an outlet conduit including a valve in sealed fluid connection to the stretch rod, and a pressure source for applying a pressure to the cryogenic liquid to cause an outflow of cryogenic liquid from the variable volume pump into the outlet conduit;
• and
• control means including a timer for opening the valve in sealed fluid connection to the stretch rod for a predetermined time interval beginning at a preselected time after formation of the container, and a pressure sensor coupled to the outlet conduit and to the pressure source for controlling the pressure of the outflowing cryogenic liquid, a detector adjustably positionable with respect to the variable volume pump for detecting displacement of an element of the pump reflecting the delivery of a preselected volume of cryogenic liquid by the pump during said predetermined time interval.