Abstract: The stream of suction gas and entrained oil flowing from the evaporator in a parallel compressor refrigeration system is directed into a flow separator where it diverges and is expanded into a separation chamber of increased cross-sectional area. A takeoff conduit has an inlet end disposed generally in the center of the separation chamber which faces into the suction gas flow stream. Because of the location and size of the cross-sectional area of the inlet end of the takeoff conduit, a larger portion of the suction gas flow stream and oil entrained therein bypasses the takeoff conduit inlet than enters it. The separation chamber is in flow communication, at its outlet end, with the shell of the one of the compressors which is designated to receive a majority of the suction gas and oil entrained therein. The takeoff conduit is in flow communication with the other of the compressors.

Abstract: An outdoor heat exchanger section has lower and upper cabinet sections between which a generally horizontal louvered lower section top cover is disposed. The sides of the lower cabinet section are louvered to promote the entry and upward movement of air thereinto and through a heat exchange coil disposed about the inner periphery thereof. Air drawn into the lower cabinet section is discharged though the radially louvered portion of the lower section top cover. The radial top cover louvers are angled so as to partially deflect the upwardly flowing air leaving the lower cabinet section to the horizontal. The top of the upper cabinet section is essentially flat and solid and overlies the lower cabinet section top cover louvers so that neither debris nor the elements can enter the lower cabinet section from above.

Abstract: A residential heat pump installation includes a variable speed reciprocating compressor. The compressor speed control components, which include an inverter, are cooled by diverting the refrigerant liquid line into the closed controls compartment of the outdoor cabinet section and by passing the liquid line through a block of material therein upon which the compressor speed control components are mounted. The heat generated by the speed control components is transferred through the block of material and ultimately into the liquid refrigerant which is pumped through the liquid line by the operation of the compressor. Heat generated in the controls compartment is therefore removed from the compartment by system refrigerant in an manner which does not, to any significant degree, adversely affect the overall operation and efficiency of the system.

Abstract: A first portion of a pitot tube-like device faces into the incoming stream of suction gas which enters the hermetic shell of a low-side reciprocating compressor. A second portion of the device extends downwardly toward the oil sump within the shell. The device terminates in a third portion which defines a plurality of apertures and which is immersed in the oil within the sump. The dynamic pressure or velocity head of the incoming suction gas stream is converted within the device to static pressure as a result of the resistance to flow through the device. The resistance to flow through the device is a function of, among other things, the static head at the immersed aperture locations.

Abstract: A control and method for varying the capacity of a centrifugal chiller system used to cool a liquid to a setpoint temperature. The control permits the user to select the setpoint, the control gain, and two variables that determine a first deadband and a second relatively wider deadband about the setpoint. If the absolute value of the difference (error) between the actual fluid temperature and the septoint is increasing, the control uses the first deadband, and conversely, if the error is decreasing, it uses the second deadband to vary chiller capacity. The control also permits the user to select a limit for various operating parameters associated with protective shutdown of the system to avoid catastrophic failure, and adjusts the chiller capacity according to one of two predefined functions of the deviation of the operating parameter from its limit, dependent on whether that deviation is greater or less than a predefined deadband.

Abstract: A thrust bearing for use between two parallel plates in relative orbital motion. The bearing includes a plurality of rollers disposed between the plates. Each roller comprises two opposing cones joined at their base with one cone in rolling line contact with one plate and the other cone in rolling line contact with the other plate. As one plate orbits relative to the other, each rolling line contact sweeps a circular area on its respective plate.

Abstract: A combination heat shield/gasket is disposed between abutting components in a reciprocating compressor. The heat shield/gasket includes strategically located protuberances, at locations where the components do not directly abut, the tips of which contact one of the components causing the heat shield/gasket to locally deflect away from the contacted component. The deflection of the heat shield/gasket at such non-abutting locations causes a dead space to be created between the component contacted by the tip of the protuberance and the heat shield/gasket. The dead space so created is a barrier to the transfer of heat, as is the heat shield/gasket itself, from the component contacted by the protruberances to the area on the side of the heat shield/gasket opposite that side on which the dead space is created.

Abstract: A heat exchanger tube assembly having one end of a copper tube soldered to the end of an aluminum tube, and a method of minimizing galvanic corrosion at the soldered joint. The aluminum tube, having a roughened inner surface for enhanced heat transfer, fits inside the copper tube at the soldered joint. A heat shrinkable thermoplastic tube having a thermosetting adhesive inner coating is placed around the joint and then heated. The heat shrinks the thermoplastic tube, causing it to contract and to adhere tightly against and around the joint. The plastic tube with its adhesive inner coating protects the joint from atmospheric moisture and thus inhibits galvanic corrosion that would eventually create a leak in the tube joint.

Abstract: A control and method for varying the capacity of a centrifugal chiller system used to cool a liquid to a setpoint temperature. The control permits the user to select the setpoint, the control gain, and two variables that determine a first deadband and a second relatively wider deadband about the setpoint. If the absolute value of the difference (error) between the actual fluid temperature and the setpoint is increasing, the control uses the first deadband, and conversely, if the error is decreasing, it uses the second deadband to vary chiller capacity. The control also permits the user to select a limit for various operating parameters associated with protective shutdown of the system to avoid catastrophic failure, and adjusts the chiller capacity according to one of two predefined functions of the deviation of the operating parameter from its limit, dependent on whether that deviation is greater or less than a predefined deadband.

Abstract: In a heat pump system for selectively heating or cooling a plurality of zones with a corresponding plurality of zone heat exchangers, the subject invention is used for preventing refrigerant condensate from flooding any inactive heat exchangers. Each zone heat exchanger is typically connected to both a liquid line and a gas line for passing refrigerant therethrough. The invention includes an arrangement of valves disposed only on the liquid line of each zone heat exchanger and eliminates the need for an additional shut-off valve on the gas line. When the heat pump system operates in the cooling mode, each zone heat exchanger functions as an evaporator with the invention operating as an expansion valve, regulating the refrigerant flow entering the heat exchanger to meet the temperature conditioning demand.

Abstract: A microprocessor-based frequency shift keying (FSK) data communications module. The microprocessor selectively modulates and demodulates data directly in terms of a square wave pulse train in which a first frequency is used to convey a binary "1" and a second frequency to convey a binary "0". An input and an output port on the microprocessor are selectively coupled to a transmission line through a transformer, by means of electronic switches. Also included are a bandpass filter for shaping the square waves into sine waves and for filtering noise, and means including a notch filter for generating a carrier detect signal input to the microprocessor, when incoming data is detected on the transmission line. Many of the components in the module are used for both transmitting and receiving data.

Abstract: This controller is used for controlling a centrifugal compressor along its path of minimum power consumption while avoiding a surge condition. It is especially useful in a refrigeration system having a variable speed centrifugal compressor with adjustable inlet guide vanes. In such an application, the controller opens the inlet guide vanes enough to satisfy the cooling demand and then, to minimize power consumption, reduces the speed of the compressor while further opening the vanes (compensating for the reduced speed) until either the inlet guide vanes are fully open or an impending surge condition is detected. The onset of a surge condition is detected by monitoring motor current fluctuations. When fluctuations above a predetermined amplitude occur in excess of a predetermined frequency, the controller determines that a surge is impending.

Abstract: A dual mode controller used to allow only one of either a primary heating/cooling system or a hot water heater to operate at one time. It is particularly useful where utility billing is based on peak demand. A two-position switch is used to select the mode such that in one switch position the heating/cooling system is given priority regardless of the operating status of the hot water heater, and in the other position the operating load is given priority. This relatively simple circuit includes one conventional relay and either another conventional relay or a pilot duty relay energized by an integral "doughnut" type current transformer.

Abstract: A retrofit assembly for adapting two replacement rooftop air handling units to a multizone installation that originally had only one air handling unit. The two replacement units include one heating unit and one cooling unit, while the original unit typically had provided both heating and cooling to several zones in the building. The retrofit assembly includes a valve manifold and a curb adaptor that make it possible to use the building's existing roof curb and air ducts. The curb adaptor supports the cooling unit on top of the existing roof curb and includes an air duct for conveying air from the existing return air ducts in the building to the inlet of the cooling unit. The heating unit is mounted on its own separate roof curb and the valve manifold receives the air discharged from both replacement units and directs it into the existing plurality of supply air ducts which further convey the air to the plurality of zones in the building.

Abstract: An oil distribution system for supplying lubricating oil to a thrust bearing, the bearing surfaces of an Oldham coupling, and a swing link bearing in a scroll compressor and allocating the oil between the bearings in proper proportion. Oil is pumped from a reservoir in the bottom of the compressor shell upward through a gallery that runs the length of a rotating drive shaft. The oil exits an opening at the top of the drive shaft and is thrown radially outward into a shallow cavity formed in a swing link that is rotatably driven by the shaft. The cavity is generally elongate in shape, so that oil collects in pools at each of its ends as a result of centrifugal force. Each of the two bearings is lubricated by oil that flows upward into the bearings either directly or through a passage from the pools of oil.

Abstract: A centrifugal fan includes a fan wheel having airfoil blades mounted for pivotal movement about their center of gravity. A yoke mechanism exterior of the fan wheel, when moved axially of the fan wheel drive shaft axis, causes actuator rods to move through the sidewall of the fan wheel. The axial movement of the actuator rods is translated first into rotary movement of a quill hub relative to the fan wheel and finally to radial movement of blade pivoting levers interior of the fan wheel. The movement of the blade pivoting levers causes the pitch of the individual fan blades to be changed in accordance with the degree of movement of the yoke mechanism. The yoke mechanism, actuator rods, quill hub and blade pivoting levers operate independently of the fan wheel so that blade pitch can be varied over an operating range irrespective of whether the fan wheel is stopped or is rotating.

Abstract: This invention is an improved "Oldham coupling" for use in a scroll machine to prevent angular rotation of one of the scroll members relative to the other. The coupling is of simplified one-piece construction that can be stamped from sheet metal in a single operation. The preferred embodiment is an oval-shaped stamped ring having four tabs extending from its perimeter at 90.degree. intervals. Two of the tabs, at opposite sides of the ring, slidingly engage slots in one of the orbiting scroll members while the other two tabs slidingly engage slots disposed either in the stationary frame of the scroll machine or in the other scroll member.