Abstract: Two variable position supply air valves, one for modulating warm airflow to a comfort zone and the other for modulating cool airflow, each have a constant intermediate open position to provide at least a desired minimum airflow, and both can be controlled so that only one valve is open at any one time to minimize any mixing of the airstreams. Potentiometers are used to adjust the intermediate open position of each valve and to adjust at least one valve's relationship of valve opening to zone temperature.

Abstract: A corner member for an air conditioning equipment cabinet includes a three-sided corner portion from which six discrete legs extend. The disposition of the legs and the existence of an open seam between two of the three sides of the corner portion of the corner member makes the corner member flexible and self-fixturing during the process of cabinet assembly yet results in an assembled cabinet which is both rigid and strong.

Abstract: An air valve actuated by an electric motor has a cylindrical inlet section. The inlet section defines a seating surface upstream of which is a support grid. A backplate, upon which the actuating motor is mounted, is fixedly supported by a plurality of rods that extend downstream of the inlet section. A damper assembly includes a generally planar damper mounted for movement axially of the inlet section. The damper assembly includes a splined rod which extends upstream and into a cooperating spline in the support grid. A threaded spindle extends downstream of the damper plate through a cooperatively threaded motor-driven drive gear which is mounted for rotation on the backplate. Because a portion of the damper assembly is splined, the damper assembly cannot rotate and is driven axially within the valve by the rotation of the drive motor and drive gear.

Abstract: A tube arrangement for a tube-type heat exchanger. The tube arrangement provides for the location of the tubes in the upper portion of the drum defining the combustion chamber of the heat exchanger. In one embodiment, four heat exchange tubes are provided, with two of the tubes disposed such that the axial center line of the tube lies across the horizontal center line of the heat exchanger drum, and with two tubes disposed entirely above the horizontal center line of the drum.

Abstract: In a compressor of the hermetic, scroll-type, a motor engaging drive shaft having a net axial thrust load determined by the pressure of compressed fluid acting upon the opposing ends of the shaft. In the preferred embodiment, the shaft includes a first end in the discharge pressure portion providing a first plan view area and a second end in the suction pressure portion having a circular, eccentrically disposed cavity with a second plan view area. The shaft has an axial bore for communicating refrigerant at discharge pressure through the shaft between the respective ends such that refrigerant at discharge pressure acts in opposite directions upon both of the respective plan view areas to balance the net thrust load of the shaft.

Abstract: A variable capacity refrigeration system includes a control scheme having three interrelated closed loops. The system includes a refrigeration system controller and at least one variable speed, electronically commutated DC motor driving a compressor. In the first closed loop, the controller supplies a speed command signal to a motor drive which governs the speed of the motor driven compressor. The speed of the compressor varies the system's capacity to condition the temperature of a comfort zone. A temperature sensor in the zone provides a temperature feedback signal to the controller to complete the first closed loop. In the second closed loop, the speed command signal from the controller is varied in response to a speed feedback signal received from a compressor drive which includes both the motor and the motor drive. The third closed loop is between the motor drive and the motor.

Abstract: A method of controlling a refrigeration compressor involves momentarily energizing the compressor after extended off periods. When the temperature of a comfort zone remains below its set point temperature for an extended period, such as at night, periodically energizing the compressor for brief periods improves the confort level of the zone.

Abstract: An economizer for an air handler, air conditioner or similar unit. The economizer has a first position and a second position. In the first position, the economizer is retracted and presents a relatively flat end surface of the air handler, and in a second position the economizer projects from the air handler and provides for the intake of ambient air into the air handler. The invention provides for the shipment of the economizer intact with the air handler so that installation of the unit is conveniently achieved.

Abstract: Apparatus and method for selectively determining the resonant frequency of a gas compressor including a compressor drive motor and a muffler in a generally spaced relationship, and an apparatus mechanically linking the compressor drive motor and the muffler. The apparatus as disclosed in one embodiment includes two conical frustums as wedge members, each having an axial bore accommodating a single non-resilient shaft for joining the conical frustums such that the shaft may be adjusted to force the wedge members closer together, biasing the muffler with respect to the compressor drive motor, and thereby adjusting the resonant frequency of the compressor structure to a determined resonant frequency.

Abstract: In an island type refrigeration display cabinet, a top aperture containing two oppositely disposed louvers for discharging oppositely directed coplanar air curtain sections, to form a single air curtain of multiple section in the top aperture of the display cabinet. Preferably, the cabinet also includes means for withdrawing air from the interior display space of the cabinet and forcing the air through a bifurcated conduit. Each bifurcation of the conduit is flowably connected to one of the respective louvers in the top opening of the display cabinet. Each bifurcation of the conduit also includes means for refrigerating the air flowing through the conduit to the louvers.

Abstract: A solenoid valve used as an expansion valve in a refrigeration circuit has an opening that varies as a function of the pulse width of a high frequency PWM (pulse width modulated) control signal. A transistor controls the electrical current delivered to the solenoid valve. The PWM control signal rapidly cycles the transistor on and off at a constant frequency that is sufficiently high to prevent the valve from having enough time within a cycle to move between fully open and closed. As a result, the valve balances at an intermediate position determined by the relative lengths of the on and off periods of each pulse cycle. The relative on-off pulse widths, often referred to as, "duty cycle", is varied in response to a temperature sensor to control the flow of refrigerant through the refrigeration circuit. The duty cycle is also adjusted to compensate for any variations in the supploy voltage applied across the solenoid valve.

Abstract: The variable opening of a pressure independent supply air valve for a building ventilation system is controlled in response to a standard airflow transducer whose output is modified to emulate a close tolerance transducer. In a calibration mode, a microcomputer based control closes the valve and a summing amplifier reduces the transducer output by an amount equal to a compensation signal provided by the microcomputer. Once the output is reduced to a predetermined desired level, the value of the compensation signal is stored in memory for later use during a run mode. In the run mode, the actual supply airflow rate is determined based upon the transducer output less the compensation signal. And the control adjusts the position of the valve until the actual airflow rate meets a desired airflow rate as determined by a room thermostat.

Abstract: An automated heat exchanger tube expander includes an automatically adjustable tool stop, an automatically adjustable back support, and a universal base support. The adjustable stop, the back support, and the base support function together to facilitate the manufacturing of various size tube and fin heat exchangers. The automatic tube expander avoids the time consuming set up for each different size heat exchanger normally required by manual tube expanders.

Abstract: A perforated plastic baffle for a shell-and-tube heat exchanger includes pressure actuated tube seals. Heat exchanger tubes run lengthwise through a cylindrical shell, and baffles traverse the tubes. The pressure actuated seals line each baffle perforation through which the tubes extend. Each seal includes a flexible annular lip that surrounds the tube and extends upstream from the baffle. Fluid flowing through the shell and being redirected by the baffles provides a pressure differential that forces the seals' lips tightly against and around the tubes. In the absence of the fluid pressure differential, the sealing force is greatly reduced which enables the tubes to be easily inserted through the baffle perforations during assembly of the heat exchanger.

Abstract: A liquid/gas bypass line bypasses an expansion device of a refrigeration apparatus. An inlet of the bypass line is connected slightly above the bottom of a condenser so that it can pass either liquid refrigerant or vaporous refrigerant, depending on the level of liquid refrigerant in the condenser. The other end of the bypass line is connected to discharge into the evaporator, bypassing the expansion device. The bypass line functions as a conventional hot gas bypass during low load conditions when the level of liquid refrigerant is below the line's inlet. When the level rises above the inlet, often occurring when the condenser coolant temperature is low and the compressor is fully loaded, the bypass line returns excess accumulated liquid refrigerant to the evaporator. Maintaining the proper levels of liquid refrigerant in both the condenser and the evaporator not only provides the most effective use of their heat transfer surfaces, but also promotes the proper return of oil to the compressor.

Abstract: A lubricant composition with decreased solubility in a liquid refrigerant and increased foaming characteristics useful in refrigeration systems to promote oil return to a compressor. A lubricant composition comprises a base lubricant, synthetic paraffinic oil, and a foaming agent. These ingredients are blended in predetermined amounts, so that when the lubricant is used in the refrigeration system, an oil rich layer will form atop the liquid refrigerant in the system's flooded evaporator, and a thick, stable foam will form when vaporized refrigerant boils up through the oil rich layer. The oil foam is then drawn through a connection at the top of the flooded evaporator and returned to the compressor.

Abstract: A pressure independent variable air volume valve (VAV valve) functions as a pressure dependent valve upon detecting a malfunctioning airflow indicator. Under normal operating conditions, the VAV valve modulates supply airflow to a comfort zone in response to the zone temperature and the rate of airflow through the valve. If the airflow indicator fails, the VAV valve modulates the supply airflow in response to the zone temperature, independent of the airflow indicator.

Abstract: A premix furnace burner for a gas combusting furnace. The furnace burner includes a premix chamber and a burner plate assembly. The burner plate assembly is comprised of a burner plate with a plurality of relatively small apertures for the passage of a mixture of combustible gas and air and an annular ring for retaining the burner plate. The annular retaining ring determines the capacity of the furnace burner by appropriately sizing of the opening in the annulus of the retaining ring to sealingly overlay a selected portion of the burner plate apertures. The retaining ring further secures the burner plate in the correct operational position while simultaneously permitting the burner plate to expand and contract in response to temperature changes induced by combustion of the gas and air mixture.

Abstract: Inside the hermetic shell of a scroll compressor, a normally closed solenoid valve seats against the back side of a stationary scroll plate to close a discharge opening through the plate. A coil circuit that actuates the valve has an electrical resistance that increases with temperature. The temperature dependent resistance allows the coil circuit to also function as a discharge temperature sensor. Should the discharge gas over-heat, the compressor motor and the valve are de-energized in response to the resistance exceeding a predetermined limit. The closed valve prevents backflow from rapidly reversing the rotational direction of the compressor, which can be extremely noisy and damaging to the compressor. Both the valve and the compressor motor are energized at the same time, regardless of the compressor's direction of rotation.

Abstract: A compressor discharge valve assembly including a valve seat, a valve cage, and an annular ring-type valve operating therebetween. The valve cage includes a recess into which the valve retracts when in an open position, or in an alternative embodiment, the valve cage includes a lip portion for shielding the valve. In either embodiment, a reduction in valve flutter and the noise, known as chatter, which results from valve flutter is realized. The valve in alternative embodiments also includes an annular dished portion oriented toward the valve seat for directing the flow of discharge gas smoothly from the compressor and thereby further reducing valve chatter.