x series with advance micro - Sunbelt Transport Refrigeration

2.3.4 CompressorThe compressor assembly includes the refrigerant compressor,suction and discharge service valves, highpressure switch, and the suction and discharge pressuretransducers. The compressor draws refrigerantgas from the evaporator and delivers it to the condenserat an increased pressure. The pressure is such thatrefrigerant heat can be absorbed by the surrounding airat ordinary temperatures.2.3.5 Compressor UnloadersThe refrigeration compressor used is a 41 cfm model05G, equipped with unloaders as standard equipment.Unloaders are used as a compressor capacity control tounload the compressor during periods of reduced loads.This provides closer temperature control and reducespower required to operate the compressor; thusreducing fuel consumption.a. Major Working PartsS Solenoid and valve systemSSSpring loaded piston type bypass control valveSpring loaded discharge check valveb. Unloaded Operation (Figure 2-12)Pressure from the discharge manifold (Item 15) passesthrough the strainer (9) and bleed orifice (8) to the backof the piston bypass valve (7). Unless bled away, thispressure would tend to close the piston (6) against thepiston spring (5) pressure.With the solenoid valve (1) energized, the solenoidvalve stem (2) will open the gas bypass port (3).Refrigerant pressure will be bled to the suction manifold(10) through the opened gas bypass port. A reduction inpressure on the piston bypass valve will take placebecause the rate of bleed through the gas bypass port isgreater than the rate of bleed through the bleed orifice (8).When the pressure behind the piston has been reducedsufficiently, the valve spring will force the piston bypassvalve back, opening the gas bypass from the dischargemanifold to the suction manifold.Discharge pressure in the discharge manifold will closethe discharge piston check valve assembly (14)isolating the compressor discharge manifold from theindividual cylinder bank manifold.The unloaded cylinder bank will continue to operate fullyunloaded until the solenoid valve control device isde-energized and the gas bypass port is closed.42 35671111089121314151.2.Solenoid ValveValve Stem3.4.Gas Bypass PortSpring Guide5.6.SpringPiston7.8.Piston Bypass ValveBleed Orifice9.10.StrainerSuction Manifold11.12.Cylinder Discharge ValveValve Plate13.14.Cylinder Suction ValveDischarge Piston Check Valve Assembly15. Discharge ManifoldFigure 2-12. Compressor Cylinder Head Unloaded62-106832--12