Abstract: The disclosed hot water extraction cleaning machine employs a conventional canister-type wet/dry vacuum cleaner having a suction tool communicating through a wand and a suction hose to a recovery tank in the vacuum cleaner. Hot cleaning solution, held in a supply tank or reservoir mounted on the wand, is pumped under pressure to a spray nozzle, positioned adjacent to the suction tool, in order to spray a jet of atomized cleaning solution onto an area of the carpet material or floor material to be cleaned. As the operator draws the suction tool across the sprayed area, the cleaning solution, with entrained dirt from the material, is sucked into the recovery tank. A hand-controlled valve permits the operator to control the flow of cleaning solution to the spray nozzle.

Abstract: To ensure continuous uninterrupted operation of an a-c line voltage-energized microcomputer in the event of a power failure, the line voltage is effectively sensed and in response to a substantial reduction thereof battery power is supplied to the microcomputer before such a reduction can adversely affect the operation of the microcomputer.

Abstract: To maintain a continuous non-interruptible d-c operating voltage for powering a load, where the operating voltage is produced from a-c line voltage subject to failure or low voltage transients, the required operating voltage is provided by two rechargeable batteries which are alternately connected to the load. While one battery supplies the d-c power to the load, the other battery is being charged by a battery charger which is driven by the a-c line voltage. As the active battery slowly discharges and the d-c operating voltage drops to a predetermined threshold level, the battery connections are automatically switched, the charged battery being connected to the load while the discharged battery is coupled to the battery charger for recharging. The connections to and from the batteries include SCR's which receive gating pulses only when a battery switch is to occur. No continuous gating signal is needed.

Abstract: By controlling the phase angle at which conduction occurs in the SCR's in an SCR rectifier bridge, a d-c voltage of adjustable magnitude may be produced from a-c line voltage applied to the bridge. The specific angle at which the SCR's are fired into conduction during each half cycle of the a-c line voltage is determined by comparing a ramp-shaped pulse, produced from the line voltage during each half cycle, with an error signal which varies as a function of the difference between the desired d-c magnitude and the actual amplitude of the d-c voltage. The d-c power supply is made immune to line voltage variations by regulating the ramp-shaped pulses so that they always have the same pulse width regardless of line voltage amplitude, thereby facilitating precise control over the d-c magnitude.

Abstract: In an air compressor-driven system, wherein compressed air and fuel are combined in a combustion chamber to produce hot gas for driving a turbine which then rotates the air compressor, surge is prevented by sensing an appropriate parameter, such as the flow rate of the compressed air at the compressor discharge outlet, and developing therefrom a feedback signal which varies the fuel flow to the combustion chamber to dynamically vary the compressor speed (and hence capacity) so that the discharge pressure versus discharge flow rate characteristic curve of the compressor always has a negative slope at the operating point, regardless of where that point is located on the curve. By providing a negative slope at all operating conditions, even when operating in the surge region of the pressure-flow plot, the system is incapable of surge.

Abstract: Faulted bipolar transistors in a voltage source transistor inverter are protected against shootthrough fault current, from the filter capacitor of the d-c voltage source which drives the inverter over the d-c bus, by interposing a small choke in series with the filter capacitor to limit the rate of rise of that fault current while at the same time causing the d-c bus voltage to instantly drop to essentially zero volts at the beginning of a shootthrough fault. In this way, the load lines of the faulted transistors are effectively shaped so that they do not enter the second breakdown area, thereby preventing second breakdown destruction of the transistors.

Abstract: A magnetic transducer fits over a rotatable shaft and has a primary winding that is a-c energized by an a-c excitation signal to produce a magnetic field, adjacent to the shaft, which changes as the shaft is torsionally stressed when torque is applied thereto. This stressing causes compression and tension in the shaft which alter the shaft permeability and thus vary the magnetic flux pattern in the shaft. The magnetic field is also a function of the shaft speed due to the shaft's armature reaction, eddy currents being generated in the shaft which develop a magnetic field that opposes and distorts the field produced by the primary winding. A pair of secondary windings in the transducer produce differently modulated excitation signals which are then processed to provide a pair of suppressed carrier signals amplitude modulated at different phases by the torque and speed parameters of the shaft.

Abstract: The power factor in an inverter-driven induction motor is held relatively constant at a desired optimum value, despite variations in mechanical loading on the motor, by monitoring the d-c bus current to determine the ratio of real and reactive currents, thereby to detect the actual power factor. The actual and desired power factors are then effectively compared and the resulting error signal is fed back to the inverter's d-c power supply to adjust the inverter output voltage to change the reactive current to the extent necessary to maintain the desired power factor.

Abstract: A pulse-width modulated inverter system and a method for operating the same is described for providing three-phase power to a load at a preselectable output frequency and a preselectable output voltage wherein modulated inverter logic control circuitry is provided for activating switching devices to produce waveforms at output terminals having at least one pulse of a variable width disposed symmetrically about the center or 90.degree. point in the middle 60.degree. portion in each half cycle thereof. The width of the pulses are varied continuously to obtain the preselected output voltage. The number of pulses to be added in the middle 60.degree. portion in each half cycle of the waveforms is increased automatically and continuously as the preselectable output frequency is reduced.

Abstract: Separation of lubricating oil, entrained in the discharge gas produced by a rotary vane compressor, is achieved in a relatively small space by initially passing the oil-laden discharge gas through a first closed chamber, containing an oil separating element, to form a stream of gas having some of its oil removed and having a desired velocity uniformly distributed across the stream's cross section. The gas stream is then circulated within a second and larger closed chamber where the remaining oil is separated out by gravity settling and impingement on the second chamber's walls. The separated oil collects in a reservoir at the bottom of the second chamber to form an oil pool. The oil-free discharge gas exits through an outlet in the second chamber.

Abstract: An upshift gear ratio change is made in an automatic transmission by monitoring the driveline torque and operating a closed loop control system in response to that torque to in turn control the torque to obtain a desired shift. Shift quality is optimized, while torque transients are minimized, by initially closing the loop at the end of the static phase of the upshift when the driveline torque drops to its minimum turnaround point, the torque thereafter being controlled such that it increases from the turnaround point at a specified rate and in accordance with a predetermined first ramp command. As the increasing driveline torque then reaches a prescribed reset level, at an early stage in the dynamic phase, the closed loop control system is released and reset in order to control the torque in accordance with a second ramp command, the second ramp, that the torque is made to follow, thereby starting at a higher level than the first ramp.

Abstract: Cathodic protection of a deep well submersible pumping assembly against the corrosive effect of electrolysis is achieved by providing a DC voltage source at the downhole pumping assembly, the negative terminal of the source being electrically connected to the metal surfaces which are in contact with the well fluid while the source's positive terminal is electrically connected to a sacrificial anode submerged in the well fluid. Current flows from the anode to the metal surfaces to reverse the process of electron flow caused by the electrolytic corrosion, thereby inhibiting the corrosion process on the metal surfaces. In effect, the corrosion is transferred to the sacrificial anode.

Abstract: Surge in a compressor-driven system, such as a refrigeration system, is precluded by sensing an appropriate parameter, for example the gas flow at the compressor discharge outlet, and developing therefrom a feedback signal which dynamically varies the capacity of the compressor so that the discharge pressure versus discharge flow rate characteristic curve of the compressor always has a negative slope at the operating point, regardless of where that point is located on the curve. By providing a negative slope at all operating conditions, the system is incapable of surge. In order to satisfy variable load requirements, the compressor capacity is adjusted to vary the steady state operating point on the characteristic curve.

Abstract: Highly accurate metering of particulate material is achieved by employing a rotatably mounted agitator to initially move the material radially outward to the periphery of a horizontally-disposed, stationary, circular, flat support plate, from which it falls, under the guidance of a cylindrical wall depending from the plate's periphery, to an annular-shaped support area of a horizontally-disposed, stationary, circular, flat metering plate. A rotatably mounted metering rotor, driven concurrently with the agitator, sweeps the particulate material radially inward from the support area to a centrally located discharge orifice in the metering plate. With such an arrangement, the particulate material will be maintained in an uncompacted state and the mixture will remain homogeneous, with the result that the volume of the material flowing through the discharge orifice will be directly proportional to the number of revolutions of the metering rotor. A precise volume may thus be fed to a collection station.

Abstract: By closing a series-connected first solid state switch, such as a triac, AC line voltage is applied directly to the first of two field windings of a two-phase reversible AC induction motor to drive the motor in one of its two directions. The shifted phase voltage, appearing at the other or second field winding, has a magnitude of about twice that of the line voltage and is employed to supply gate current to the first solid state switch over a cross-coupling circuit. Conversely, when motor rotation in the opposite direction is desired a second solid state switch or triac is rendered to conductive to apply the AC line voltage directly to the second field winding, the gate current for the second solid state switch being derived from the high magnitude shifted voltage appearing at the first winding. Since the gating voltage is phase displaced (by approximately 90.degree.

Abstract: A controlled space is maintained at a desired set point temperature by adjusting the evaporator boiling pressure in a refrigeration system, thereby controlling the evaporator capacity (namely, the amount of cooling imparted to the air supplied to the space) which is inversely proportional to the evaporator boiling pressure. When the space temperature tends to vary from the desired set point due, for example, to a changing heat load, the control system automatically changes the refrigerant flow through the evaporator to establish the evaporator boiling pressure (and hence the boiling temperature) at the control point required to cool the air sufficiently to maintain the controlled space at the desired temperature. More specifically, in response to a space temperature increase, the flow rate of the refrigerant increases to decrease the evaporator boiling pressure; and in response to a drop below the set point, the refrigerant flow decreases to increase the evaporator boiling pressure.

Abstract: Constant condenser pressure is maintained in an air-cooled condenser of a refrigeration system which operates at either full capacity or reduced capacity depending on the heat load requirements. When operating at full capacity, the condenser head pressure will be held generally constant at a relatively high control point even in the presence of wide variations in condenser cooling air temperature. On the other hand, when the heat load requirements decrease and the refrigeration system switches to its reduced capacity operating mode, the control point automatically drops to a substantially lower level, whereupon the condenser pressure is maintained relatively fixed at that lower control point despite major changes in the condenser cooling air temperature. By automatically lowering the control point at reduced system capacity, maximum efficiency and economical operation are obtained.

Abstract: A controlled space is maintained at a desired set point temperature by adjusting the refrigerant temperature at the evaporator outlet in a refrigeration system, thereby controlling the evaporator effectiveness or capacity which is inversely proportional to the outlet temperature. When the space temperature tends to vary from the desired set point due to a changing heat load, the control system automatically changes the refrigerant flow through the evaporator to establish the evaporator outlet temperature at the control point required to maintain the controlled space at the desired temperature. More specifically, in response to a space temperature increase, the flow rate of the refrigerant increases; and in response to a drop below the set point, the refrigerant flow decreases.

Abstract: Cross-contamination of the patients using the same sitz bath in a health-care institution is precluded by lining the bath with a disposable sheet of biologically-clean, flexible plastic film, thereby establishing a physical barrier to prevent any contact (and consequently a transmission path for bacteria) between the sitz bath and patient and between the bath and water. A plastic collar or grommet, which surrounds and extends through a drain opening in the liner, inserts into the bath's drain. Water may be run continuously into the lined sitz bath and drained out through the collared drain opening. To provide a predetermined water level in the sitz bath, a plastic standpipe is inserted into, and held by, the plastic collar.

Abstract: A controlled space is maintained at a desired set point temperature by adjusting the refrigerant temperature at the evaporator outlet in a refrigeration system, thereby controlling the evaporator effectiveness or capacity which is inversely proportional to the outlet temperature. When the space temperature tends to vary from the desired set point due to a changing heat load, the control system automatically changes the refrigerant flow through the evaporator to establish the evaporator outlet temperature at the control point required to maintain the controlled space at the desired temperature. More specifically, in response to a space temperature increase, the flow rate of the refrigerant increases; and in response to a drop below the set point, the refrigerant flow decreases. Such control of the flow rate is achieved by varying the displacement of a controlled displacement compressor included in the refrigeration system.