Abstract: A method of operating a transport refrigeration system having a six cylinder compressor and a prime mover operable at a selected one of low and high speeds, to control the temperature of a served space by cooling and hot gas heating modes. Below a set point temperature 100, system heating capacity is controlled at the low compressor speed by the step 127 of unloading compressor cylinders and the step 129 of reloading compressor cylinders. A temperature rise of the served space above a set point temperature 106 controls cooling capacity by a combination of alternative steps 135, 137, 139, 141, and 143 which may or may not change the number of loaded compressor cylinders, and may or may not change compressor speed, based upon two predetermined trigger events which relate to what the temperature of the served space does relative to time 136 and 142, a set point temperature 106, and a temperature 108 above set point which is normally associated with a change in compressor speed.

Abstract: A transport refrigeration system using a three-way valve 14 for either cooling mode operation and defrost and/or heating mode operation is provided with a thermal storage sink 28 having first and second heat exchangers 26 and 52 and a heat exchange medium 30 therein which serves to sub-cool refrigerant in its passage to the evaporator 36 in a cooling mode, and which serves to evaporate refrigerant in heat exchanger 52 in a defrost mode after the refrigerant has passed through the defrost heat exchanger 42 for defrosting evaporator 36. The stored heat in the medium 30 in the sink serves to hasten the defrost cycle.

Abstract: A transport refrigeration unit of the mechanical refrigeration type and including a start-stop mode of operation is driven by an engine 20 which is coupled through belt 34 to a common shaft 32 for the condenser fan 26 and evaporator fan 30, through a clutch 38 which is selectively operable to drive the shaft 32 when the engine 20 is operating, and to decouple from the shaft 32 when the engine 20 is not operating so that ram air pressure to the condenser fan will in turn drive the evaporator fan to provide at least some air circulation in the interior space of the trailer.

Abstract: A refrigerated trailer 10 which is subject to having a restricted normal return air flow path back to the refrigeration unit 24 through the suction space 46 in communication with the return air inlet 34 of the unit, due to volume and arrangement of the load 42, is provided with secondary air return ducts 48 and 50 which are also in communication with the suction space 46 to ensure an adequate return air flow to the unit and thereby also assuring an adequate discharge of air to the rear 22 of the trailer.

Abstract: A transport refrigeration system of the type which can provide either cooling or heating includes a pressure regulating valve 42 controlling hot gas to the evaporator during a heating cycle and operable to prevent an excessive suction pressure, and a pressure regulating valve 74 between the two outlet sides of a three-way valve and operable to pass refrigerant from the hot gas line 34 to the condenser 30 when the hot gas pressure is excessive, the arrangement limiting the values of both the evaporator suction pressure and the hot gas discharge pressure to prevent overloading in heating and defrost operations.

Abstract: A hot gas pressure switch 29 is provided to be responsive to pressure in a hot gas line 22 which will have a significant pressure value only during a heat or defrost mode, to unload cylinders of a transport refrigeration compressor to avoid overload, so that the compressor can operate with a substantially greater discharge pressure in a cooling mode without penalty.

Abstract: A spring biased member is disposed between the facing surfaces of the reversing eccentric and the rotor of a reversible, unidirectional flow pump. The member is keyed to the eccentric and applies frictional torque to the eccentric from the rotor to drive the eccentric to the proper position as determined by a fixed stop in accordance with the rotor's rotation. The member extends generally tangentially beyond either side of the contact points on the circular rotor face and presents a wedge-shaped confined space to the lubricant on the rotor face. The lubricant is driven into the wedge by the rotating rotor and raises the member from intimate contact with the rotor surface to maintain a thin lubricant film therebetween. This film of lubricant thus separates the member from the rotor face whenever there is relative motion between them to reduce wear on the otherwise contacting parts.

Abstract: The invention relates to a system that can provide the refrigeration function of a compression refrigeration system, or by changing the position of some valves in the system, the system can provide a defrost function, or a heating function, or a capacity controlled refrigeration function. To accomplish the defrost or heating function compressed refrigerant is condensed in a heat exchanger that is in heat exchange relationship with a main evaporator and the liquid refrigerant thus formed passes through an expansion valve to an auxiliary evaporator. When the system operates to provide a capacity controlled refrigeration function, the capacity of the main evaporator is controlled by heat of compression from the heat exchanger that is in heat exchange relationship with the main evaporator. The amount of heat from this heat exchanger that counteracts the cooling effect of the main evaporator can be varied by dissipating a variable amount of the heat of compression before it reaches this heat exchanger.

Abstract: This invention relates to a compression refrigeration system having means for removing some of the oil refrigerant foam which is formed in a crankcase at startup. The removal of foam with entrained oil from the crankcase is to reduce the amount of oil pumped with the refrigerant through condenser and evaporator and at the same time rapidly return oil to the crankcase during startup. In one embodiment of the invention, oil refrigerant foam goes from the crankcase to a foam trap where the foam collapses, the oil drains back to the crankcase, and the refrigerant vapor is drawn to an intake of the compressor. In another embodiment, oil refrigerant foam passes to a suction accumulator where the foam collapses, refrigerant vapor is drawn to an intake of the compressor and the vapor carries droplets of separated oil to a point where they drain back to the crankcase.