Importance

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Abstract

A control for use with an expendable refrigeration system is disclosed which has particular use in refrigerated transport applications. The control is used to regulate the injection of refrigerant into the space to be refrigerated and provides an accurate means of precisely selecting a preferred ratio of 'on' to 'off' timing segments in each cycle and the number of complete cycles in a given time frame. In one embodiment of the invention, pneumatic pressures are used to power an oscillating device, the number of oscillations are counted to a selectable total. Attainment of the chosen total causes the counter to transmit a signal, which signal actuates the operator of a four-way valve. The switching of the valve provides the means to (a) open a liquid line valve to inject the refrigerant into the refrigerated space and (b) reset the counter, terminate the actuation signal and start the next cycle count. A time delay-on release device, itself capable of adjustment, is used to delay the return switching of the four-way valve, hence the duration of the 'on' timing segment.

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First Claim