In addition to supplying oil pressure to the compressor lubrication system, the compressor oil pump also provides oil pressure to operate the compressor capacity control system. ‘SANLAN' Unloader Power Elements are used in this capacity control system.
Normally, Unloader Power Elements are manufactured and supplied as per the specifications of the customers.
TECHNICAL INFORMATION FOR TYPE UNL-1
The compressor capacity control system is actuated by means of high-pressure oil from the compressor oil pump. Oil pressure to the power Elements loads the associated cylinders and release of this pressure unloads them.
The Unloader Power Elements type UNL-1 is fastened into the compressor deck between the suction gas chamber and the crankcase. The element consists of a stationary piston and movable cylinder. The movable cylinder engages the unloader sleeve which is free to move up or down on the cylinder sleeve. When oil pressure is admitted to the power element, the movable cylinder pushes the unloader sleeve down and permits the suction valve to operate normally and permit refrigerant gas compression. When oil pressure to the power element is relieved through the capacity control solenoid valves, the spring-loaded cylinder moves the unloader sleeve up raising the suction valve off its seat by means of lift pins. In this position the cylinder is completely unloaded.