Liquid spray device with adaptive duty cycle

Apparatus for cooling the refrigerant-containing vessels of a refrigeration or air conditioning unit, which comprises:

• valve means including an inlet port for receiving a cooling fluid from a source and an outlet port for delivering said cooling fluid when said valve means is open;
• nozzle means for receiving said cooling fluid from said outlet port of said valve means and for directing said cooling fluid onto said refrigerant-containing vessels;
• control means for opening and closing said valve means for variable time periods that are proportional to the temperature sensed at a control point in said unit, said control means including timing means having a predetermined period that consists of an on cycle and an off cycle, the time periods of said on and off cycles within said predetermined period being variable in proportion to said temperature, wherein said timing means includes first timer means for producing an output signal during said on cycle, said control means responsive to said output signal for opening said valve means;
• and
• means for sensing said temperature of said unit at said control point comprising a thermistor means whose resistance decreases as said temperature increases, wherein said first timing means includes means responsive to a decrease in resistance of said thermistor means for decreasing the time period of said output signal, whereby said valve means is opened for a longer period of time during said predetermined period in response to an increase in said temperature.