Abstract: A control for a multi-stage heating and cooling system used to temperature conditioning a comfort zone. The control includes a microprocessor responsive to a temperature sensor installed in the comfort zone. Heating and cooling setpoints and a lookup table including a plurality of ranges for deviation of the comfort zone from the setpoint temperature and associated limits for the rate of change of the comfort zone temperature used in determining specific staging control actions are stored in solid state memory accessed by the microprocessor.The stages of temperature conditioning are controlled as a function of both the deviation of the zone temperature from the heating or cooling setpoint (depending on the system operating mode), and the rate of change of zone temperature. The mode of operation, i.e., heating or cooling, is determined by the relative values of the zone temperature and the heating and cooling setpoint.
Abstract: This invention is a method for pre-expanding a heat exchanger tube prior to its insertion into a tube sheet. A tubular mandrel having an elastic bladder sheath sealed at each end is inserted into the tube and positioned at the point where the tube is to be expanded. A die with an annular recess approximating the shape to which the tube is to be expanded is clamped around the outer surface of the tube, concentric to the mandrel. The elastic bladder is then pressurized with hydraulic fluid pumped through a passage in the mandrel, thereby deforming the tube outward so that it conforms to the recess in the die. A heat transfer enhancement treatment thereafter may be applied to the exterior of the tube between the expanded sections, without concern that it may crack off when the tube is installed in a tube sheet. In addition, the hydraulic pre-expansion process prevents or minimizes cracking of the tube which sometimes occurs when a tube is expanded to an equivalent diameter in a single operation.
Abstract: A system for lubricating the main drive shaft bearings in a scroll compressor enclosed within a hermetic shell. The drive shaft and its main bearings are supported in a frame that defines first and second chambers adjacent each end of a main bearing. Each of the chambers includes an opening to a spatial volume contained within the compressor shell. An oil pump at the lower end of the drive shaft supplies oil through a bore in the shaft to a swing link bearing and a thrust bearing, both disposed adjacent its upper end. Oil is dispersed into the spatial volume as a mist of oil droplets by the rotating elements connected to the drive shaft. Fan means are disposed within the second chamber and are operative to develop a differential pressure between the two chambers so that oil droplets are drawn toward the first chamber, lubricating the main bearing as they pass through it.
December 27, 1982
Date of Patent:
December 18, 1984
The Trane Company
Arthur L. Butterworth, James C. Tischer, Robert E. Utter
Abstract: A control for a variable capacity reciprocating compressor water chiller system. A microprocessor connected to monitor return and supply fluid temperature sensors in the system is programmed to vary the compressor capacity in response to the deviation of the return and supply chilled water temperatures from desired values. The control determines these desired values as a function of predetermined full load return, supply, and reference temperature setpoints, and as a function of the relative loading of the chiller system. The control also functions to selectively offset the chilled water temperatures in one of three control modes. If zone temperature sensors are connected to the control, the offset is a function of the deviation of the weighted average zone temperature from a setpoint. The second control mode allows offset as a function of the outdoor ambient air temperature, and the third, as a function of a temporary setpoint.
Abstract: A microcomputer controlled charge control system for modulating charge in a heat pump refrigerant circuit. A charge receiver has its interior in thermal communication with the compressor suction line and has a single charge flow line connected via a charge control valve to the refrigerant circuit at a point intermediate two controllable expansion valves in the high side of the circuit. Super-heating and subcooling strategies are employed to maintain the charge level in the circuit at optimum performance levels, automatically adapting to changes in environmental load conditions on the heat pump heat exchange coils.
Abstract: A bi-directional flow auxiliary heat exchanger is disposed in proximity to the outdoor heat exchanger of a heat pump. The auxiliary fin and tube coil is active in both the heating and cooling modes to subcool refrigerant fluid flowing from the condenser. During operation of the heat pump system in the cooling mode, the entire auxiliary coil is used for subcooling; however, a portion of the subcooler is bypassed during heating mode operation to reduce the effective size of the subcooler. The bypassed portion of the auxiliary coil is used for storing excess refrigerant charge. This arrangement provides the system with the optimum amount of subcooling in each mode of operation, and adjusts the refrigerant charge for optimum performance in both the heating and cooling modes.
Abstract: A plate-type heat exchanger having uniform surface temperature and improved structural strength is disclosed, which may be used as a structural support member for an object to be temperature controlled, and which provides a surface having an exceptionally uniform temperature for either heating or cooling the object. The heat exchanger includes a fin pad and a machined plate having a fluid passage therein, as well as other structural frame and support members. The major circuit flow direction of the fluid in the passage is perpendicular to the major longitudinal fin direction of the fin pad in the preferred embodiment. All components of the heat exchanger are of material having good thermal conductivity and structural strength, and the components are brazed or otherwise secured together to provide good thermal conductivity and structural reinforcement throughout.
June 28, 1982
Date of Patent:
October 23, 1984
The Trane Company
Irwin R. Friedman, Harry D. Foust, Alan G. Butt
Abstract: A wrap element and tip seal are disclosed for use in fluid apparatus of the scroll type which include a wrap element having a groove disposed within its tip surface of spiroidal configuration generally conforming to that of the wrap element. A tip seal is disposed within the groove and comprises a relatively rigid strip of material having been wound about its longitudinal axis into a spiroidal configuration generally conforming to that of the groove, the strip of material having a cross section taken in a plane substantially perpendicular to its longitudinal axis wherein at least the radially outer surface thereof is convex in a radially outward direction. This configuration for the tip seal has the advantage that it may be formed using conventional winding techniques wherein a certain amount of "twist" about the longitudinal axis of the strip of material is normally encountered.
Abstract: A plate type heat exchanger in which liquid is injected into a vaporous fluid stream through orifices in a hollow slotted bar. The hollow bar is disposed transversely to the longitudinal axis of the heat exchanger, between and abutting facing surfaces of two metallic sheets. Vaporous fluid is admitted and distributed across the width of the heat exchanger in a first passage defined by the two metallic sheets, and flows through channels formed in the hollow bar where it abuts the sheets. The vaporous and liquid fluids mix, and after passing in heat transfer relationship with another fluid flowing in a second passage defined by adjacent metallic sheets, exit the heat exchanger. Since the hollow bar extends between the metallic sheets, it provides an effective structural support, permitting the heat exchanger to be used at relatively high operating pressures.
Abstract: A thermostat used to control a temperature conditioning system to heat or cool a comfort zone to a heating setpoint and a cooling setpoint. The thermostat is microcomputer based and includes both a digital keypad and display for setpoint entry by an operator. Control means in the thermostat automatically insure that at least a predetermined minimum offset is maintained between the heating and cooling setpoints stored in memory, and the control means are further operative to adjust one of the setpoints if the operator enters a value for the other setpoint that is in error.
Abstract: Tube circuits for heat exchangers which provide same-end inlet and outlet connections are disclosed, in which each circuit includes conduits of two types. In a preferred embodiment, the first type conduit has two tubes and is generally U-shaped, and the second type conduit has four tubes. The inlets for each conduit are disposed adjacent each other in the assembled heat exchanger, as are the outlets for the conduits. To equalize flow and pressure drop a turbulence promoting device can be disposed in the U-shaped conduit. The circuits can be used for providing same-end connections on coils previously available only in opposite end connection configurations, such as for example, three-row full-circuited and six-row double circuited coils.
Abstract: An impeller for a centrifugal oil pump having improved head and flow output capabilities, which impeller can be machined into the end of a crankshaft. A plurality of radially extending tunnels are disposed horizontally in the crankshaft, with outlets in the perimeter of the crankshaft. An annular groove is provided in the crankshaft, with a groove opening in the bottom surface of the crankshaft and a subtending groove surface defining the depth of the groove. The subtending groove surface is normally narrower than the groove opening, and the groove intersects the tunnels, exposing a part of the tunnel walls to a flow of fluid from directly below. The exposed tunnels act as vanes to scoop oil from the groove and accelerate it to crankshaft speed. Entrained gases collect near the subtending groove surface, and a vent passage is provided to conduct the gases out of the impeller.
Abstract: Apparatus for unloading a scroll compressor to modulate its capacity by separately controlling fluid flow into first and second inlets. The first and second inlets are disposed diametrically opposite each other in a fixed scroll plate, and are enclosed by a perimeter wrap which extends from the radially outer end of the fixed spiral shaped wrap element. A compliant sealing member is provided between the inner surface of the perimeter wrap and the outer flank surface of the orbiting scroll wrap to interrupt fluid flow between the two inlets through this area. Valves connected to the first and second inlets selectively control the flow of suction fluid into fluid pockets being formed between the radially outer ends of the orbiting and fixed wrap elements to unload the compressor over an extended range of its rated output capacity.
Abstract: In a scroll compressor, means for maintaining the motion of an orbiting plate in fixed angular relationship to a stationary plate and for modulating the capacity of the compressor. The orbiting and stationary plates include intermeshed wrap elements of similar spiral shape about an axis. A coupling ring is slideably disposed between the plates and sealingly encloses the wrap elements. Four slots are provided in the coupling ring, aligned at right angles to each other and spaced apart around its inner circumference. Three segments, extending outward from the wrap elements, sealingly engage these slots. The fourth slot is engaged by a sliding key attached to one of the plates. The segments separate a first and a second fluid inlet and cooperate with the slots in the coupling ring to constrain the orbiting plate's motion in fixed angular relationship to the stationary plate.
Abstract: A centrifugal oil pump for a compressor having improved head and flow performance in which a plurality of tunnels extend radially outward and angularly upward from the face of the impeller and convey oil to the perimeter of the drive shaft during operation. The oil is collected in a chamber of a housing around the bottom of the crankshaft, flows through a channel of an end plate and is transmitted upwardly in a bore of the crankshaft. Entrained gases are vented from each inlet hole to a common annular ring, and through a vent from the annular ring upwardly in the crankshaft.
Abstract: A tip seal back-up member is disclosed for use in fluid apparatus of the scroll type, which member comprises a strip of material extending longitudinally in generally spiroidal configuration about a reference axis and having a preformed configuration such that its radially inner and outer edge portions are disposed axially with respect to each other. The strip of material comprises an elastic material such that as one of the edge portions is displaced axially toward the other, an opposing spring force is developed. In operation, the back-up member is disposed within a groove located in a tip surface of a wrap element in fluid apparatus of the scroll type, between a bottom wall of the groove and a tip seal. Preferably, the strip of material is generally flat between its radially inner and outer edge portions and is constructed from steel.
Abstract: A wrap element and tip seal are disclosed for use in fluid apparatus of the scroll type which include a wrap element having a groove disposed within its tip surface of spiroidal configuration generally conforming to that of the wrap element. A tip seal is disposed within the groove and comprises a plurality of strips of material disposed at least partially within the groove and arranged in side-by-side relationship at least partially across the width of the groove, each said strip extending along a longitudinal axis about the spiroidal configuration of the groove. By fabricating the seal from a plurality of strips of material, the necessity for expensive machining operations is obviated while a seal is provided which is relatively flexible in a radial direction as to accommodate the precise groove shape, while remaining relatively inflexible in an axial direction so as to provide the desired sealing characteristics.
Abstract: A rolling thrust bearing for use in a scroll type positive fluid displacement apparatus is disclosed. In the invention, a plurality of ball bearings spaced apart in cavities formed in a bearing cage are operative to transmit an axial force between a supporting frame and an orbiting scroll member. The bearing cage rotates within a groove in which it is seated due to frictional forces between its flank surfaces and the sides of the groove. In a first embodiment, the diameter of the cavities is substantially larger than the diameter of the ball bearings, and the bearings are free to orbit within the cavities as the bearing cage rotates. In the second embodiment, the cavities are only slightly larger in diameter than the ball bearings, but the radial width of the bearing cage is substantially less than the width of the groove, and the bearing cage and the ball bearings together describe an epicycloidal path about the central axis of the bearing cage.
Abstract: A positive fluid displacement apparatus of the scroll type, having a swing link for translating the rotational motion of a drive shaft into the relative orbital motion of two parallel end plates. The facing surfaces of the parallel plates have involute wrap elements attached in fixed angular, intermeshed relationship with each other. Contacting surfaces of the parallel plates and wrap elements define pockets of fluid which are subjected to changes of pressure and volume as the pockets are caused to move between an inlet and an outlet by the orbital motion of the plates.A flexible member of resilient material connects a crank post on the drive shaft with the swing link and transfers the driving force of the drive shaft to the swing link. The flex member is rigid in tension, but flexible in bending. By its spring force, the flex member biases the wrap elements slightly apart when the drive shaft is not rotating, to reduce the driving torque required at start-up of the scroll apparatus.