Abstract: A combination sight glass and optical sensor is provided in the housing of a hermetic compressor to provide effective visual inspection in addition to automatic sensing of the level of oil in an oil sump. A sight glass fitting is provided in the housing and has a first portion that extends outwardly from the housing and that is accessible from outside the compressor. An optical oil level sensing device is removably attached to the first portion of the sight glass with electrical leads extending outside the compressor for connection to a compressor controller. A prism or similar device is attached to the sight glass fitting intermediate the sump oil and the optical sensor. The sensing device includes a light source, a photosensitive detector, and an opaque member to prevent cross coupling between the light source and the detector.

Abstract: A solid motor controller for controlling the current in an electrical motor. The motor controller includes a processing unit, and a solid state switch operatively connected to the electrical motor. The motor controller senses the current through the motor, compares the current with a reference current level, and limits the current in the motor by rapidly switching the switch between an ON and an OFF state when the current exceeds the reference current level. The controller de-energizes the motor by placing the switch in the OFF state when the current exceeds the reference current for a predetermined period of time. The controller also includes a second solid state switch which is controlled to rapidly stop the rotation of the motor. The motor controller also activates a high current warning when the current exceeds a high current limit.

Abstract: The present invention involves a refrigeration system. The refrigeration system comprises an electrical compressor motor, a line adapted to be connected to an electrical power line and a thermostat control circuit. The thermostat control circuit comprises a thermostat responsive logic circuitry coupled to a temperature sensor associated with the compressor and a solid state motor control circuit. The solid state motor control circuit includes a relay circuitry, power switch circuitry, compressor starting circuitry with an overload timer, high voltage protection circuitry, under voltage protection circuitry and run current limiting circuitry. The relay circuitry includes an optical coupler and triac to provide line voltage to the compressor through a start resistor. The power switch circuitry includes a pair of SCR's connected in parallel as a switch to allow current to flow through the compressor.

Abstract: The present invention involves control and protection circuit for a compressor motor which includes an inductively activated contactor for controlling the flow of current to the compressor motor. The circuitry of the present invention includes a plurality of current detectors associated with each phase winding of the compressor motor for sensing the current in each phase winding. The sensed currents are combined in a predetermined manner and used to provide protection against an overcurrent condition, single phase operation and light loading condition. Additional detector circuits are also connected to the present control and protection circuit to provide protection against high temperature in the compressor motor windings, high temperature in various component of the compressor motor, and undervoltage in the power supply.

Abstract: The present invention involves an inductively activated silicon switch for a control and protection circuit for motors and compressors. The circuit includes a logic gate for combining both motor control and protection functions. The logic gate has inputs from a thermostat, a compressor shell temperature circuit, a fan overheat detection circuit, a motor start relay circuit, and motor load sensing circuits. The logic gate output is connected to an oscillator for inductively activating the power output stage, as well as a start relay, a compressor shell temperature hysteresis circuit, and a fan timer circuit connected to the fan control circuit. The control circuitry further includes an over-ride circuit for manually allowing a limited number of immediate restart attempts.

Abstract: The present invention involves an inductively activated silicon switch for a control and protection circuit for motors and compressors. The circuit includes a logic gate for combining both motor control and protection functions. The logic gate has inputs from a thermostat, a compressor shell temperature circuit, a fan overheat detection circuit, a motor start relay circuit, and motor load sensing circuits. The logic gate output is connected to an oscillator for inductively activating the power output stage, as well as a start relay, a compressor shell temperature hysteresis circuit, and a fan timer circuit connected to the fan control circuit. The control circuitry further includes an over-ride circuit for manually allowing a limited number of immediate restart attempts.

Abstract: The present invention is an inverter for a portable refrigerator. The inverter includes a square wave generator operable by a DC voltage source. A timer is also included which, in conjunction with the square wave generator, provides a multiple phase waveform for operating a compressor motor. For conventional three winding compressor motors, the inverter provides a six-step waveform for operation of the portable refrigerator. The inverter can also drive the motor using either a first or second DC voltage level, by minor changes in the inverter and using either a wye or delta winding configuration. The inverter also includes a protection circuit which protects against locked rotor and overload current conditions, as well as a shut-off circuit to guard against operating at low speeds and completely draining the battery.

Abstract: The present invention is a liquid level control system for selectively activating and deactivating a pump according to the liquid level indicated by capacitive sensors. Activating circuitry starts the pump motor when both upper and lower sensors indicate the presence of liquid. The pump motor is latched on by the activating circuitry and continues operation until the lower capacitive sensor indicates the absence of liquid, in which case the pump is shut off. A high frequency oscillator operates reliably over a wide range of operating conditions to maintain relatively constant charging time for the capacitive sensors.

Abstract: The present invention is a cold control for refrigerators. The cold control circuit includes temperature sensitive resistances disposed within the cold box portion of the refrigerator. The cold control circuit senses the temperature of the cold box portion by a NTC thermistor which is disposed in the cold box portion and connected to the control circuit. When the temperature rises above the turn-on set point, the NTC thermistor has a relatively small resistance and activates a transistor. The transistor is connected to a latching circuit which maintains activation of the refrigerator until the thermistor falls below the turn-off point. Another solid state switch of the control circuit activates the refrigerator compressor, such as a transistor turning on an inverter in a DC powered refrigerator and a triac directly supplying current in an AC powered refrigerator.

Abstract: The present invention is a liquid level control system for selectively activating and deactivating a pump according to the liquid level indicated by capacitive sensors. Activating circuitry starts the pump motor when both upper and lower sensors indicate the presence of liquid. The pump motor continues operation until both of the capacitive sensors indicate the absence of liquid, in which case the pump is shut off. The circuitry of the present invention operates reliably over a wide range of operating conditions.

Abstract: A combined alternator-compressor including a brushless excitation structure for the alternator. The magnetic flux field for the alternator is generated by a rotating permanent magnet ring structure and a stationary toroidal control coil which is arranged concentrically with and between the rotating permanent magnet ring and an alternator base. The control coil is mounted in additive and subtractive magnetic relationship with the permanent magnet ring for control of the magnetomotive excitation field of the alternator.

Abstract: A unitary alternator-compressor including a clutch assembly for the compressor. The clutch assembly continuously drives the alternator rotor and selectively drives the compressor crankshaft. A single bearing supports the alternator rotor. The clutch includes a drive pulley and a flange member which is rotatably secured to the rotor by means of a plurality of drive pins. The pins are retained in position by a locking nut which also engages with and clamps the outer race of the bearing. The inner race of the bearing is clamped by a second nut.

Abstract: A direct current, variable duty cycle control circuit for the manual control of the supply of power from a direct current source to a motor is disclosed including a transistor arrangement operable when enabled to couple the direct current source to the motor along with means for enabling that transistor arrangement during an operator determinable portion of each of a series of time intervals and a sensing circuit receptive to an overload condition of the transistor arrangement for disabling that transistor arrangement. The disclosed system includes an operator control member effective in a first position to prevent the energization of the motor by preventing the supply of electrical power to the control circuit, effective in a second series of positions to vary the portion of each time interval during which the motor is supplied power and effective in a third position to deliver power continuously to the motor by bypassing the transistor arrangement.

Abstract: A combined pump and generator arrangement for use in a vehicle having an engine as the prime mover is disclosed and includes a pump housing with an axially extending actuating shaft and a rotatable member to be driven by the engine to rotate about that actuating shaft with the rotatable member including a fan and a pulley as well as a magnetic arrangement for providing a rotating magnetic field when the rotatable member is driven by the engine. An annular stator assembly is fastened to a face of the pump housing and has windings for providing a voltage in response to the rotating magnetic field. The actuating shaft and annular stator assembly are concentrically disposed with the stator assembly lying intermediate the actuating shaft and the magnetic arrangement of the rotor. The pulley, stator and magnetic arrangement and the fan are supported progressively more remote from the pump housing face.

Abstract: A permanent magnet alternator is connected directly across the battery through a full-wave bridge rectifier. The bridge includes a pair of controlled rectifiers which are selectively rendered conductive to charge the battery through the bridge when the battery voltage drops below a preset value. A Zener diode and one transistor monitor the battery voltage and control a second transistor which in turn controls gating current from the alternator to the controlled rectifiers.

Abstract: A three-phase permanent magnet alternator is disclosed employing a fractional pitch stator winding of about two-thirds or 120 electrical degrees for minimizing third harmonic circulating current in the phase windings. The alternator has a rotor supporting permanent magnet poles and a slotted stator having coils disposed in the slots with the pitch of each coil being less than the rotor pole pitch and the coils of each phase connected in series to form a fractional pitch phase winding. The rotor circumscribes the stator and the permanent magnet poles have an arcuate extent nearly as great as the rotor pole pitch.

Abstract: A pump such as a vehicle air conditioner compressor has a compressor shaft, a continuously engine-driven flywheel and means such as an electromagnetic clutch for selectively coupling the flywheel to the shaft to operate the pump. The flywheel also provides a permanent magnet field which field rotates with the flywheel and induces in the windings of a relatively stationary annular stator assembly an electric voltage in response to the rotating magnetic field. The pump shaft, annular clutch actuating coil, annular stator assembly, and permanent magnet flywheel are all generally concentrically disposed and in the order stated. The flywheel is driven any time that the engine is running thereby inducing a voltage in the stator windings and that flywheel also drives the exemplary compressor when the clutch is actuated.

Abstract: A battery powered inverter power supply for recreational vehicle refrigeration units or the like which is adapted to operate in a DC mode wherein power is supplied to the inverter and refrigeration unit from a vehicle battery, and in an AC mode wherein power is supplied to the refrigeration unit from a source of normal household power. A cold control circuit is responsive to a thermostatic sensor within the refrigerated enclosure to apply battery power to the inverter power supply only when the supply is operating in the DC mode and cooling is required. A battery charger is operable during the AC mode to automatically recharge the vehicle battery.

Abstract: A pump such as a vehicle air conditioner compressor has a compressor shaft, a continuously engine-driven flywheel and means such as an electromagnetic clutch for selectively coupling the flywheel to the shaft to operate the pump. The flywheel also provides a permanent magnet field which field rotates with the flywheel and induces in the windings of a relatively stationary annular stator assembly an electric voltage in response to the rotating magnetic field. The pump shaft, annular clutch actuating coil, annular stator assembly, and permanent magnet flywheel are all generally concentrically disposed and in the order stated. The flywheel is driven any time that the engine is running thereby inducing a voltage in the stator windings and that flywheel also drives the exemplary compressor when the clutch is actuated.