Abstract: The flow, use, interaction and separation of lubricant and gas flowing through the suction pressure portion of a low-side refrigeration scroll compressor is managed by the use of a drive motor mounting sleeve (46) and a multi-ported frame (40). The mounting sleeve and frame provide for the direction of oil to surfaces within the low side of the compressor shell which require lubrication as well as the conduct of suction gas to the scroll compression mechanism in a manner which cools the compressor drive motor yet which maintains the respective flows of oil and suction gas sufficiently separate to ensure that excessive amounts of oil are not conducted out of the compressor in the gas which is compressed thereby. Lubrication is enhanced by the use of a vent passage (68) which opens into a relatively lower pressure region within the suction pressure portion of the compressor shell.

Abstract: A noise reduction curb for use as an interface with a rooftop air conditioning unit by forming a base upon which the air conditioning unit rests and is mounted on a roof of a building. A noise reduction supply air duct is oriented in the longitudinal dimension of the air conditioning unit and has a supply air inlet fluidly coupled to the supply air source and a supply air outlet fluidly coupled directly to the supply ducts in the building. The supply air inlet is longitudinally displaced from the supply air outlet and is separated therefrom by a flow turbulence reducing substantially straight duct section. A noise reduction return air duct is oriented in the lateral dimension of the air conditioning unit and has a return air inlet fluidly coupled directly to the return air ducts in the building and a return air outlet fluidly coupled to the air conditioning unit. The return air inlet is laterally displaced from the return air outlet.

Abstract: The position of a slide valve in a screw compressor in a refrigeration system is controlled using a gaseous medium sourced from the higher pressure one of two or more sources of such fluid. Preferred sources are refrigerant gas in a closed compression pocket in the working chamber of the compressor and refrigerant gas in the discharge passage downstream of the compressor's discharge port. The multiple sources of such gas are connected to a solenoid valve which, when open, permits gas to act on the piston which controls the position of the slide valve. Due to a check valve arrangement, it is always the one of the sources of gas which is at higher pressure that acts on the slide valve actuating piston. The adverse affects of refrigerant gas out-gassing and gas bubble collapse associated with use of hydraulic fluid rather than a gaseous medium to modulate compressor capacity are avoided while advantageous use is made of compressor overcompression in the control of slide valve position.

Abstract: Noise reduction in a screw compressor based refrigeration system is achieved by the use of multiple compressor discharge and/or suction lines. The lines are configured and/or fabricated from materials which reduce system noise which would otherwise be induced by vibration as well as the system noise associated with gas pulse energy in the discharge gas stream flowing from the compressor.

Abstract: An oil separator for a refrigeration system employing a screw compressor includes a generally cylindrical, vertically upstanding housing the bottom of which defines an oil sump and the top of which is penetrated by discharge conduit connecting the oil separator to the refrigeration system condenser. The center line of the discharge conduit is parallel to but offset from the center line of the separator housing so that the discharge conduit is non-concentric with the housing. As a result, an enlarged tangential inlet to the interior of the separator is made possible which is unimpeded by the discharge conduit. The cross sectional flow area through which the mixture discharged from the compressor passes prior to entering the separator can therefore likewise be increased. As a result, pressure drop in the refrigerant gas as a result of the oil separation process is reduced and overall system efficiency is enhanced while the diameter of the separator housing is minimized.

Abstract: Liquid refrigerant interacts with the stream of gas flowing through in a centrifugal water chiller, downstream of the occurrence of the compression process in the compressor portion of the chiller but prior to the condensing of the gas in the chiller condenser, to reduce the acoustic energy of the gas. The noise emanating from the chiller which would otherwise result from the interaction of the discharge gas with the piping connecting the compressor portion of the chiller to the system condenser and/or with the components of the system condenser itself is thereby reduced without significantly affecting chiller performance or efficiency.

Abstract: A thermostat that includes a subbase having a back surface designed to be mounted conformal with a surface and an inner surface that has a portion of selected electrical components mounted thereon, including a first electrical communication device. The subbase has first mechanical connectors formed integral therewith. A cover that has a front surface designed to carry selected components for communication with an operator and an inner surface that has a portion of selected electrical component supported thereby, including a second electrical communication device. The inner surface has second mechanical connectors formed integral therewith. During installation, the cover is brought into registry with the subbase to form a thermostat housing that has a reduced profile and that substantially encloses the electrical components of the thermostat.

Abstract: A high side co-rotational scroll compressor has lubricant sumps in both the discharge and suction pressure portions of its hermetic shell as well as a pressure biasing arrangement by which the scroll members are urged together in operation to minimize internal leakage. Lubrication of the bearing in which the driven scroll member rotates as well as to the bearing in which the idler scroll member rotates, both of which are located in the suction pressure portion of the shell, is provided for. Additionally, embodiments are taught by which the interface between the tips of the wraps of each scroll member and the end plate of the opposing scroll member are lubricated and by which the seal in the axial pressure biasing arrangement is lubricated and/or shielded from debris having the potential to damage it.

Abstract: Protective apparatus in a scroll compressor, in the form of a valve assembly, is operative to prevent compressor damage from reverse direction rotation of the scroll compression mechanism or the development of abnormally high discharge gas temperatures. The valve assembly is disposed in a passage communicating between the suction and discharge pressure portions of the compressor shell and houses a discharge temperature sensor immediately adjacent the location from which discharge gas issues from the compression mechanism. The location of the sensor and its exposure to discharge gas permits the timely sensing of abnormally high discharge temperatures and the shutdown of the compressor upon their occurrence.

Abstract: A high side co-rotational scroll compressor has lubricant sumps in both the discharge and suction pressure portions of its hermetic shell as well as a pressure biasing arrangement by which the scroll members are urged together in operation to minimize internal leakage. Lubrication of the bearing in which the driven scroll member rotates as well as to the bearing in which the idler scroll member rotates, both of which are located in the suction pressure portion of the shell, is provided for. Additionally, embodiments are taught by which the interface between the tips of the wraps of each scroll member and the end plate of the opposing scroll member are lubricated and by which the seal in the axial pressure biasing arrangement is lubricated and/or shielded from debris having the potential to damage it.

Abstract: A method of utilizing an economizer to reduce the energy usage of a mechanical refrigeration system. The method comprises the steps of: economizing if both cooling demand and the prerequisites to economize are present; measuring economizer capacity; determining if the measured economizer capacity is sufficient to meet the needs of a zone being conditioned; continuing to economize as long as there is both a cooling demand and the prerequisites to economize; and initiating the use of the mechanical cooling system only if the economizer capacity has been determined to be insufficient to meet the needs of the zone being conditioned.

Abstract: An apparatus and method for protecting an induction motor from momentary power loss in a three-phase, alternating current, power supply. The apparatus includes a circuit for detecting when the motor switches from a mode of operation as a motor to a mode of operation as a generator, and a microprocessor connected to the detector to receive the detection of a switch in mode of operation, and for generating a fault disconnect signal in response thereto to initiate disconnecting the motor from the power source. The method includes the steps of detecting when the motor switches from a mode of operation as a motor to a mode of operation as a generator and generating a fault disconnect signal in response thereto to initiate disconnecting the motor from the power source. The apparatus and method provide for robustness of the fault detection data, and for avoiding false detections of momentary power loss.

Abstract: A method of compressor over temperature protection. The method comprises the steps of monitoring the temperature of oil entering a compressor, determining an oil temperature differential between the entering and exiting oil temperatures, comparing the oil temperature differential to first and second predetermined limits, terminating compressor operation if the first limit is exceeded by the oil temperature differential, and terminating compressor operation if the second temperature limit is exceeded by the oil temperature differential for longer than a first time period.

Abstract: A high side co-rotating refrigerant scroll compressor includes a motor disposed vertically above its compression mechanism. The discharge of gas from the compression mechanism is through the drive shaft of the drive scroll member which is rotatably supported at its distal end in an upper bearing. Upper bearing lubrication is accomplished by the disentrainment of oil from the mixture of compressed refrigerant gas and oil discharged from the compression mechanism in the vicinity of the bearing and by the direction of such disentrained oil to the bearing.

Abstract: A high-side co-rotating refrigerant scroll compressor defines a lubricant sump in its discharge pressure portion. Lubricant is directed from that sump, through a passage which is at least partially defined by the shell of the compressor, to the bearings in which the scroll members rotate. Heat carried in the lubricant flowing through the passage is transferred through the compressor shell to the ambient. Subsequent to having lubricated the bearing in which the drive scroll member rotates, lubricant is diverted into a passage defined by the drive scroll member drive shaft and enters the stream of compressed discharge gas flowing therethrough. The lubricant is thereby prevented from entering the suction pressure portion of the compressor where it would otherwise heat compressor suction gas prior to the entry of that gas into the compressor's compression mechanism.

Abstract: Compressor lubricant in a screw compressor-based refrigeration system is cooled by directing the lubricant from the system oil separator to an oil-cooling heat exchanger disposed in the lower portion of the system condenser where it is bathed in condensed system refrigerant. Parasitic capacity losses with respect to the compressor lubricant cooling process are thereby avoided.

Abstract: A method of controlling the capacity of a chiller system, the chiller system including a circularly linked compressor, condenser, expansion device, and evaporator. The method comprises the steps of: measuring a first chiller system parameter; determining a first parameter error as a function of the difference between the first parameter and a first setpoint; measuring a second chiller system parameter; determining a second parameter error as a function of the difference between the second parameter and a second setpoint; providing a first mode of capacity control where the compressor is modulated in response to the first parameter error and the expansion valve is modulated in response to the second parameter error; and providing a second mode of capacity control where the compressor is maintained at a minimum capacity and the expansion valve is modulated in response to the first parameter error.

Abstract: A variable flow rate expansion valve designed for in-line installation in a fluid conveying conduit such as between the high pressure condenser and lower pressure evaporator of a refrigeration system includes an integrally defined restrictor disc and a closure disc for controlling the flow of fluid through the valve. The restrictor disc has a first set of flow apertures and the closure disc a second set of flow apertures. The closure disc is rotatably coupled to the restrictor device in a plane parallel to the plane of the restrictor disc and perpendicular to refrigerant flow. A stepper motor is coupled to the closure disc through a linear actuator. Movement of the linear actuator causes the closure disc to rotate relative to the restrictor disc such that the flow apertures of the closure disc are selectively brought into and out of registry with the apertures of the restrictor disc.

Abstract: A thermostat and method for controlling the overshoot and undershoot of the temperature in a zone that are caused by an air conditioning system responsive to a change in the setpoint of the thermostat is disclosed. The thermostat includes a sensor for detecting the temperature in the zone and being adapted to generate a signal representative of the temperature. A processor for controlling the air conditioning system is communicatively coupled to the sensor and receives the signal representative of the temperature of the zone therefrom. A setpoint input device for changing the setpoint of the thermostat is communicatively coupled to the processor and is adapted to provide a signal representative of the changed setpoint to the processor. The processor controls the air conditioning system in a static condition mode during normal operations and switches the air conditioning system to a full on mode responsive to a setpoint change.