SEMI-FROZEN FOOD PRODUCT PRODUCING MACHINE

摘要

The present invention includes a dual purpose carbonator/blending bottle connected to a source of beverage syrup, a source of potable water and to a source of pressurized carbon dioxide gas. The dual purpose bottle is retained within an ice bank water bath tank. A pair of ratio valves provide for metering the water and syrup at a desired ratio. The mixed beverage first flows through a serpentine coil, also located in water bath, and then flow into the dual purpose bottle. A refrigeration system provides for cooling an evaporator located in the water tank for forming the ice bank thereon, The carbonated beverage then flows from the bottle into a freeze cylinder. The freeze cylinder also includes a further evaporator coiled around an exterior perimeter thereof. The freeze cylinder evaporator is connected to and cooled by the same refrigeration system that cools the evaporator in the water bath tank. A scraping mechanism within the cylinder provides for scraping frozen beverage from the inner surface of the cylinder. A control mechanism provides for controlling the refrigeration system and the cooling of both evaporators. The beverage is therefore pre-cooled to a temperature just above its freezing point before delivery to the freeze cylinder. Thus, less cooling power is needed to reduce the beverage to a frozen state. The present invention utilizes a method of controlling the operation of the refrigeration system and the cooling of both evaporators thereof. The control system provides for directing refrigerant to one or the other of the evaporators as is most efficient so as to avoid short cycling or pressure build up. The present invention uses a control strategy that can mote accurately maintain a pre-selected temperature differential between the inlet and outlet temperatures of the evaporators. The control algorithm utilizes a proportional integral differential control approach that safely permits a much narrower temperature difference so that a greater length of each freeze cylinder evaporator can be utilized for efficient heat transfer cooling,