Abstract: A method for controlling the operation of a brushless DC fan for cooling heat generating components of a system is provided. The method includes providing a system temperature signal indicative of a system temperature and providing an intelligent shutdown enable signal. The system temperature signal is compared with a shutdown temperature signal if the intelligent shutdown enable signal has a first value. The shutdown temperature signal is representative of a shutdown temperature value. The fan is operated at a generally temperature proportional speed after comparing the system temperature signal with the shutdown temperature signal if the system temperature as indicated by the system temperature signal is greater than the shutdown temperature value as indicated by the shutdown temperature signal.

Abstract: An automatic gate operator includes an electric drive motor coupled by a drive train to a movable gate, and includes provision for measuring the coasting distance which the gate moves after shut off of the drive motor. This coasting distance varies both with the weight and momentum of the gate in comparison to frictional drag of the gate hardware, and the drag provided by the gate operator with the drive motor shut off, and also varies in response to a great number of other variables many of which are unpredictable. These other variables include such factors as wind, weather, temperature, wear, adequacy of lubrication, time interval since last operation of the gate operator, and off-level installation of the gate, for example. However, the coasting distance is measured and recorded, and is subsequently used as a predictor of gate coast on subsequent operation of the gate operator in order to coast the gate to a stop precisely at a selected limit position.

Abstract: Suggested is a switching arrangement for actuating a wiper motor (10) for windshield wiper arrangements, which functions to protect the power switching element (13), designed as semiconductor, and the wiper motor (10) against permanent destruction caused by blocking and overload. The switching arrangement comprises a temperature monitoring of the semiconductor end stage (29), which short-circuits the power switching element (13) in case of a motor (10) overload and simultaneous heating up of the power switching element and shuts down the motor (10), as well as a parking position monitoring of the wiper lever, in order to shut down the motor completely if the wiper lever is blocked (FIG. 1).

Abstract: A turbogenerator/motor control system having a plurality of proportional integral control loops including a fuel command control loop and a current command control loop. The exhaust gas temperature of the gas turbine of the turbogenerator/motor is maintained at a constant value with stability is achieved by varying the sampling times of the different proportional integral controls within the control loops.

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: A controller drives a fan's motor to proportionally control fan speed based on changes in heat output from electrical components in a local environment. The controller is connected to a temperature sensor and the fan motor. The temperature sensor senses local environment temperature, while exhibiting a lag time. The controller provides closed loop control and implements a system pole which cancels out the temperature sensor lag time during steady state operations. The controller implements an integration of a difference between sensed temperature and a reference temperature to generate the system pole.

Abstract: A fan monitoring system for an electronics system or a computer system. The fan monitoring system includes a fan which produces a rotation signal, where the rotation signal is a function of the fan rotating. The fan monitoring system also includes a detection circuit responsive to the rotation signal and producing an operating signal indicative of the fan rotating. The fan monitoring system also includes a fan detection circuit having a primary connection point capable of being electrically coupled to the fan. The fan detection circuit provides a detection signal indicative of whether or not the fan is electrically coupled to the fan detection circuit. The fan monitoring system further includes an I/O circuit for receiving the fan detection signal and the operating signal. The I/O circuit providing I/O signals to a host computer system as determined by the operating signal and/or the detection signals.

Abstract: A controller drives a fan's motor to proportionally control fan speed based on changes in heat output from electrical components in a local environment. The controller is connected to a temperature sensor and the fan motor. The temperature sensor senses local environment temperature, while exhibiting a lag time. The controller provides closed loop control and implements a system pole which cancels out the temperature sensor lag time during steady state operations. The controller implements an integration of a difference between sensed temperature and a reference temperature to generate the system pole.

Abstract: In an electric power steering apparatus, it is judged whether or not a value of primary delay of temperature increase in a driving circuit for an electric motor tends to decrease, and when the value of primary delay is judged to tend to decrease, a new value of primary delay is obtained with a time constant set smaller, so that an upper limit value of a motor current can be decided on the basis of the new value of primary delay. Thus, a steering power can be rapidly recovered.

Abstract: A secondary thermal overload device is connected to one winding of a motor having a bi-directional rotatable output shaft and is preset at a lower trip temperature than a trip temperature of a primary thermal overload device connected to the motor to deactivate only the one motor winding effecting closing movement of a garage door at a lower motor operating temperature and before the primary thermal overload device trips while enabling the motor winding associated with an opening movement of the garage door to be activated to open the garage door.

Abstract: A configuration based cooling fan speed controller for use with computers and other heat intensive electronic devices. Methods of using and manufacturing the controller are also disclosed. The cooling fan speed controller generally comprises a EEPROM coupled with firmware controls. If the controller is set in manual mode, a speed input by the computer's manufacturer or service provider is used to set the starting speeds of a device's cooling fans. If the controller is set in auto mode, the device's configuration is detected, and cooling fan start speeds are retrieved from a fan speed table stored in the EEPROM. Once the lowest operating speeds for a device's cooling fans have been selected, the speeds of the device's cooling fans are ramped up or down in response to the temperature sensed by an ambient air temperature sensor. The invention holds audible fan noise to a minimum.

Abstract: A speed controller for motors of a solid fuel stove or stoker includes a bidrectional switch, such as a thyristor, to be interposed along an ac power line. The controller operates in a speed control mode for sending reduced power to a stove when a space thermostat is satisfied. The speed control mode may be automatically modulated between minimum and maximum in response to remote sensors, such as a thermistor. The controller may also provide a power-up mode for a predetermined period of time to supply full power to stove motors upon start-up, such as after a power outage. The controller may also provide full power to the stove motors when the motors are being powered by an inverter.

Abstract: A method for removing moisture from an induction motor having at least two phase windings with each phase winding coupled by a first respective parallel combination of a first switch and a first diode to a positive voltage line and a second respective parallel combination of a second switch and a second diode to a negative voltage line includes supplying voltage to the positive and negative voltage lines and switching ON and OFF selected ones of the first and second switches to provide a current to preheat the induction motor. The provided current can be a substantially DC current or a substantially sinusoidal current.

Abstract: A system includes a microcontroller for controlling a fan particularly suited to be mounted in a window. The microcontroller monitors and responds at relatively high sampling rates to the actual and desired temperatures of the room associated with the fan. The microcontroller senses a predetermined difference between the desired and actual temperatures to generate the speed, forward-reverse drive and/or on-off controls of the fan and so that the operation of the fan closely tracks the temperature conditions of the room being serviced by the fan.

Abstract: A motor speed control circuit includes a temperature sensor providing a first voltage output which is proportional to the temperature and a control voltage generator having an internal voltage reference receiving the first output as an input. The control voltage generator develops a control voltage representative of a desired motor speed profile which varies substantially linearly between a first predetermined temperature and a second predetermined temperature and supplies the control voltage to a motor drive circuit with a motor drive voltage at its output. The control voltage is fed back to the temperature sensor to achieve a controlled, fast rising slope. A second feedback circuit results in a reduced slope of the voltage between the second predetermined temperature and a third predetermined temperature at which an alarm signal is generated. The circuit also is able to detect a stopped motor and provide an alarm.

Abstract: An electric servo-drive for adjusting a control element between an open position and a closed position. The tightness of the control element in the closed position can be assured without any additional tightening device. Starting signals are issued to the drive motor by a control unit after the control element reaches the closed position, thus causing the control element to be driven further in the direction of the closed position by the drive motor.

Abstract: A protecting method and apparatus for a regenerative resistor in which a regenerative resistor is satisfactorily protected from a thermal breakage caused by an over-regeneration by combining a projection of the regenerative resistor by a thermostat and a protection of the regenerative resistor by an analog simulation circuit and by coordinating protective regions of these two protections. The heat-responsive switch (2) stops power supply to a DC link (10) when the temperature of the regenerative resistor is increased to a predetermined value or greater value. The analog simulation circuit (1) is provided with a charge-discharge circuit to be charged and discharged in response to a regenerative pulse signal from a level detector (7), estimates the quantity of heat accumulated in the regenerative resistor (5) by means of the charge-discharge circuit, and stops power supply to the DC link (10) when a predetermined threshold value is exceeded by the estimated value.

Abstract: An electric power steering device includes an output shaft connected to a steering mechanism of a steering system for power assisting the steering operation. The EPS includes a motor and a control circuit accommodated in a common motor housing. The motor housing comprises an end frame and a cup-shaped motor case hermetically covering the motor and the control circuit. The end frame is secured to a rack housing accommodating the steering mechanism, so that heat generated by the motor and the control circuit is transmitted to the rack housing.

Abstract: A temperature-compensating overcurrent detection circuit for a DC motor comprising a converter, an integrator and an overcurrent detector. The present invention provides for an overcurrent detection circuit for a DC motor that is adapted compensate for operating temperature of the motor's environment and such compensating detection circuit does not respond with an early forcible operation when the mechanical device is constrained. The overcurrent detection circuit is adapted to permit the motor to carry out its intended operation exactly without having malfunctions due to noise and a temporary overcurrent.

Abstract: When a switch 12 is turned on, a relay coil 14b is excited by a current generated at the very moment when electric power of a dc power source 11 is supplied to a condenser 16 for actuation. Accordingly, a relay contact 14a is closed, and the power is given to a dc motor 15 via the switch 12 and the relay contact 14a. As a result, the dc motor 15 is actuated. At the same time, a part of a current running through the dc motor 15 is supplied to the relay coil 14b and brings about self-hold by which the dc motor 15 remains running. After that, when the driving of a device to be driven is forcibly regulated, an excess current passing through the dc motor 15 flows to a PTC thermistor (positive temperature coefficient thermistor) 13 which is connected in series to the dc motor 15. Owing to the excess current, the temperature of the PTC thermistor 13 is raised, and thereby the resistance of the PTC thermistor 13 is heightened. As a result, the relay contact 14a is opened to stop the dc motor 15.

Abstract: A remote switch includes a fluid-containing tube connected to a fluid-sensing switch. A hot wire sensor detects changes in flow through the conduit tube and is electrically connected to breaker switch circuitry. Because the switch is responsive to flow, rather than pressure, the operation of the switch will continue, even if the conduit becomes punctured, cut or damaged. The device is particularly useful as a means for actuating a safety switch to interrupt the electrical power in an emergency.

Abstract: An air conditioner which has a controller equipped with heat-producing electrical parts and in which the driving current of a compressor, etc., is controlled by the controller, includes a temperature sensor which is provided to or in the vicinity of at least one heat-sensitive electrical part (for example, a power transistor) of the electrical parts and adapted to detect the temperature of a heat-sensitive electrical part, and means for stepwise or linearly reducing the upper-limit value of the driving current of the compressor in accordance with the increase of the detected temperature when the temperature detected by the temperature sensor is higher than a predetermined value.

Abstract: A disk drive has a microprocessor, a digital controller chip, and an analog power chip, and a multi-winding spindle motor. The power chip operates under gross and fine control to connect and disconnect, during ON and OFF phases, a supply voltage to each winding on a PWM basis. The magnitude of the supply voltage and the temperature of the power chip vary. The microprocessor sends a digital control signal to the controller chip for gross control. The controller chip sends a PWM signal to the power chip for fine control. The power chip has pins for receiving the supply voltage, for sending a modulated signal to the controller chip; and for receiving the PWM signal from the controller chip.

Abstract: An anergy conversion apparatus for generating rotational force and AC power has first and second banks of solar cells configured for continuous exposure to light. Each of the banks has a charge storage device, such as a capacitor or a battery, connected thereto in parallel. A motor assembly has a stator with coils connected to commutating solar cells disposed on said stator and the first and second banks of solar cells such that the commutating solar cells control current passing through the coils from the first and second banks of solar cells. A rotor assembly is rotatably mounted on the stator assembly and has a set of permanent magnets for producing fields interacting with fields produce by the coils and a mask for selectively shielding the commutating solar cells to apply current from the first and second banks of solar cells to the coils to effect rotation of the rotor. AC power is tapped from terminals disposed across the coils.

Abstract: An electrical load, such as a motor, has a first and a second terminal element for supplying electricity to the load. The second terminal element is directly connected to the load whereas the first terminal element together with a further terminal element forms a clamping socket for a switching device. The further terminal element is electrically connected to the load. When the switching device is inserted into the seat, the first terminal element is connected to the load in series with the further terminal element via the switching device.

Abstract: The present invention is a temperature control system for a motor coupled to a power source. The motor has at least one winding which serves as a heater and temperature sensor as well as producing torque during normal operation. The mathematical relationship between temperature and resistance in the motor winding is used to determine the winding temperature. The actual winding temperature is then compared to a desired operating temperature, and the current to the motor winding is controlled so as to keep the motor temperature within a desired range.

Abstract: In one embodiment of the present invention, a "one-touch-up" power window system is provided for a motor vehicle. The system includes a controller which controls the power window motor. One function of the controller is to determine whether an obstruction impedes travel of the power window. The controller takes a plurality of samples of the electrical current drawn by the power window motor. If the last sample varies by more than a predetermined amount from any of the past samples taken over a predetermined distance of travel of the window, the controller concludes that an obstruction impedes the travel of the window. The controller then stops or reverses the power window motor to stop or reverse travel of the power window. In this embodiment of the present invention, distance of travel of the window can be inferred from rotations of the power window motor.

Abstract: Apparatus which automates the collection of motor temperature, flux and shaft current data for proactive motor maintenance. Motor speed is determined by an analysis of the flux frequency spectrum, and motor load is determined based on speed, from which a normalized thermal parameter is then determined. From a spectrum analysis of magnetic flux signals a set of peaks each characterized by a frequency and an amplitude is found, and a subset of peaks is identified in accordance with predetermined identity criteria for purposes of comparison. Temperature, magnetic flux and shaft current data are trended to provide early indications of degradation, as well as for recognizing faults.

Abstract: This disclosure provides a motor control system and method that is preferably applied to cargo power drive units. Power is supplied to a motor having one or more windings and a thermocouple that is embedded in the motor windings. The thermocouple provides an electronic signal from which both motor temperature and rate of temperature change are derived. A motor control circuit uses these values to determine if a jam condition has occurred (as represented by improper temperature rise) or whether critical overheating is occurring. If so, the motor control circuit causes a power switch to disconnect power from one or more PDUs in the subject bank of PDUs. Power is temporarily disabled, until a cargo operator releases a joy stick control to a neutral position and then attempts to use it again.

Abstract: In a compressor for adjusting a cooling power such that a piston integrally formed with an oscillator according to the oscillation of said oscillator adjusts the amount of refrigerant absorbed into a cylinder, a cooling power controller for the compressor which can control the cooling power by varying the power itself to change the operation state of the compressor for controlling the temperature of a refrigerator or an air conditioner, includes a power source for varying input alternate power to output the same through a plurality of secondary ports, an applied voltage controller for selecting the secondary port voltage of the power source to control the cooling power of the compressor, and a comparator for comparing a predetermined temperature with the actual temperature of an heat exchanger to control the applied voltage controller.

Abstract: A rotor temperature control system for a centrifuge is provided. This system includes an ambient temperature sensor for detecting ambient temperature around the system, a temperature regulating device for regulating temperature of a rotor of the centrifuge according to an operation factor which is variable within a range of preselected maximum to minimum values, and an operation factor controller for controlling a value the operation factor of the temperature regulating device in a preselected relation to the ambient temperature and a given target rotor temperature to modify the temperature of the rotor to the target rotor temperature. With this arrangement, the temperature of the rotor is modified to a desired value quickly regardless of an initial temperature of the rotor.

Abstract: A closure system for a motor vehicle includes a closure, a closure frame, an electric motor, a control switch, an electrical power source, first and second displacement sensors, a temperature sensor, a current sensor for a current being drawn by the electric motor, and a microprocessor. The first and second displacement sensors each operably generate a signal indicative of closure movement. The microprocessor is electrically connected to the control switch, the electric motor, the first and second displacement sensors, the temperature sensor and the current sensor. The microprocessor electrically connects the motor with the power source responsive to a condition of the control switch. The microprocessor also converts the temperature sensed to an electrical signal indicative of the temperature, and converts the current sensed to an electrical signal indicative of motor current.

Abstract: An exercise machine which can independently vary the force and the speed at the user end is developed. The exercise machine includes a constant torque, variable speed reversible motor, a temperature controlled magnetic particle clutch, a gear reducer, a controller, and a suitable lever mechanism. The motor, clutch and gear reducer are chosen in a combination in order to achieve a predetermined output so that any combination of isotonic, isokinetic, isometric, isotonic/isokinetic, constant, variable, active, passive, uni-directional or bi-directional exercise routines can be performed with the exercise machine. With suitable lever modifications, the resistance providing unit can be successfully modified to emulate a shoulder press, bench press, leg exercise machine, arm exercise machine, etc. The output parameters, user force and user speed, are controlled in real time to maintain accuracy. This is made possible by the use of a PC-based controller interfaced to off-the-shelf motor and clutch control boards.

Abstract: The present invention provides a power window control system of a vehicle for raising or lowering windows that is controlled by user operated switches which supply or cut off vehicle battery power to the motor that raises or opens the window. A combination of overcurrent protection circuitry and overheating protection circuitry is used to allow switches to be used that are less expensive than the conventionally used switches which can undesirably arc and, eventually malfunction, as previously described.

Abstract: An electronic protection device for providing thermal protection of a load by cutting off the multiphase supply of power to the load includes a thermal sensor having at least one resistive element thermally coupled to a temperature sensor connected to an electronic processor circuit. This circuit generates a command instruction in response to any overload detected by the temperature sensor. Each resistive element of the thermal sensor is fed with current by a current sensor on a phase wire supplying power to the load.

Abstract: A compressor control circuit adapted to a refrigerator comprises a compressor including a brushless DC motor, a power circuit for separating an AC power source from a DC power source to drive the brushless DC motor, a voltage adjustment switching circuit for selecting the voltage of a power source circuit responsive to the load condition, and a motor control circuit including a two phase control circuit for varying the operation speed of the brushless DC motor in response to the temperature of a freezing chamber, an operation control circuit for enabling the on-off operation of the brushless DC motor to be continued according to the on-off operation of a load sensor in the freezing chamber, and an over-load protecting circuit for stopping the brushless DC motor and cutting off the power source under the overload or binding condition for the compressor.

Abstract: The electric motor is part of an electro-mechanical actuating system that is especially applicable to power assisted automotive steering systems.A phase for monitoring the cooling of the electric motor is carried out when the motor is inoperative in order to produce a value for a restarting temperature. This value is used during an electrical motor thermal control phase when the motor is operative. This prevents the motor from exceeding a maximum permissible temperature.

Abstract: An electric motor has three windings which are supplied by a three-phase source of electricity that has one polarity during a first half-cycle and another polarity during a second half-cycle. The motor is controlled by an apparatus that has three thyristor switches coupling the phases of the source to the motor windings. A switch controller triggers the thyristor switches to apply electricity that produces movement of the motor. One thyristor switch is operated to be in a first non-conductive state during a portion of every first half-cycle and in a second non-conductive state during a portion of every second half-cycle. The first non-conductive states are longer in duration than the second non-conductive states. A current sensor provides a first value that indicates the magnitude of the DC component of electric current flowing through one motor winding that is connected to the one switch.

Abstract: An asynchronous machine uses a short-circuit rotor that is rotatably mounted by means of rolling bearings. Damage to the grease-lubricated bearings of the machine is prevented when the machine is started up in a temperature range below or near the freezing point by providing that: (1) before the machine is started and while the rotor is simultaneously locked, a voltage is applied, as a function of the temperature prevailing at the machine at its stator winding, of such magnitude that a current several times the rated machine current flows; and (2) when a certain temperature is reached at predefined parts of the machine or after a certain voltage application time, the current is switched off and the locking of the rotor is released.

Abstract: A motor controller for a vehicle including an electric motor that drives the vehicle, a plurality of sensors and a vehicle power controller. The vehicle power controller receives signals from an accelerator sensor and a brake sensor, converts the signals for the accelerator sensor and the brake sensor into a torque value. The motor controller comprises three components. A first component receives the torque value from the vehicle power controller. A second component converts the torque value into a torque output; and a third component controls the motor in accordance with the torque output.

Abstract: A speed control circuit for a ventilation fan of an electronic device, such as a laser printer, adaptively varies a speed of the ventilation fan depending upon an internal temperature of the device. The speed control circuit has a temperature sensing circuit for generating a voltage depending upon the temperature, a triangular wave generator for generating a triangular wave signal having fixed period, a pulse width modulator for comparing the triangular wave signal with the voltage generated by the temperature sensing circuit and generating pulse-width modulated pulses, and a driving circuit for controlling the speed of the ventilation fan in response to the pulse-width modulated pulses so that the speed of the ventilation fan will be increased in response to an increasing temperature, for example.

Abstract: A system for conditioning air in a space by heating or cooling the air to change its temperature. A thermostat located within the space generates a two state temperature signal having a cyclic parameter which corresponds to the temperature of the air in the space as it rises and falls. A compressor supplies refrigerant to a heat exchanger by means of which changes are made in the temperature of the air. A variable speed motor drives the compressor in response to a motor control signal. A controller responds to the temperature signal and senses the cyclic parameter of the temperature signal. The controller generates the motor control signal as a function of the sensed cyclic parameter whereby the motor control signal is provided to the motor to control the torque or speed of the motor.

Abstract: A power source circuit converts direct: current (DC) power into alternating current (AC) power having a required frequency, and provides DC output power according to the AC power. The power source circuit comprises an oscillator for providing a control signal that determines a converting frequency of the AC power; an element provided for the oscillator, having temperature characteristics for increasing the converting frequency at a low temperature; and a device for determining the converting frequency of the AC power according to the control signal provided by the oscillator.

Abstract: A vehicle fan motor controller includes a simple planar ceramic base providing a plurality of printed resistors. The resistors include electrically conductive paths printed on the ceramic overcoated with a thick resistive film. The thick film substantially covers the base to promote heat transfer to air moving in the fan duct in which the controller is placed. The thick film resistors are on both sides of the base to reduce overall size and improve heat transfer. A thermal fuse comprising a spring metal member held in a normally closed position by a meltable material opens in response to a predetermined high temperature.

Abstract: The purpose of this invention is to provide secondary resistance low temperature compensation in vector speed control at values that are close to the actual secondary time constant even at startup of the motor wherein the secondary time constant operation is not carried out.The invention consists of vector speed control devices 1 to 5 of the induction motor IM, with secondary resistance low temperature compensation of the electric motor being carried out by installing a secondary time constant operator (6) which detects the secondary time constant of an electric motor; a comparator/register (7) which holds and outputs low temperature data .tau..sub.2 from a comparison of register data and the output .tau..sub.2 of the aforementioned operator (6); and a damping unit (8) which, during operation, carries out replacement of sequential data with the output .tau..sub.2 of the operator (6), and, during shutdown, which turns to the output values .tau..sub.

Abstract: A circuit for starting a single-phase AC induction motor 11 having a main winding 12 and an auxiliary winding 13, which is so constructed that a PTC element 16 and a triac 17 are connected in series with the auxiliary winding 13 and a gate voltage of the triac 17 is reduced to turn a portion between main terminals of the triac 17 off after a predetermined time period has elapsed since the motor 11 was started, and can effectively lower the power consumption without degrading starting characteristics and can shorten return time required until the motor 11 is restarted and lengthen the life of the PTC element 16.

Abstract: The negative temperature dependency of the torque ripple correction capability of a known drive circuit is offset by making the amplitude of input voltage signals applied to a m-differential amplifier of the drive circuit positively temperature-dependent to improve the overall torque ripple correction capability of the circuit so that deteriorated torque ripples at low temperature and increase in the level of reactive currents at high temperature may be effectively eliminated. Moreover, since temperature induced deformation of waveforms of electric currents to be carried to soft switching coils of the drive circuit is minimized, a too rapid switching speed at low temperature is avoided to suppress generation of electric as well as mechanical noises, while too dull waveforms of electric currents at high temperature are also eliminated.

Abstract: The residential structure ventilating apparatus disclosed herein employs a variable speed exhaust fan. The speed is responsive to a sensor which detects air temperature at the exhaust port. The fan is energized when the sensed air temperature rises above a first preselectable temperature and the external environmental air is cooler that the air at the exhaust port. The fan speed is increased progressively from about one-half full speed at the preselected turn on temperature to full speed at a predetermined higher temperature. The fan is turned off when the exhaust port temperature falls below a second preselected temperature, lower than the first preselected temperature or when the external environmental temperature rises above the inside temperature, the fan speed being essentially constant between the first and second preselected temperatures.

Abstract: An airflow register for an air conditioning system for an enclosure such as room within a house or an office within a building. The register includes a series of louvers which can be located in either an open position or a closed position. The open position permits air to flow through the register and the closed position prevents air from flowing through the register. Louvers are to be movable by a motor with this motor being operated by a light sensor mounted on the exterior surface of the register. Upon an observable lightened environment being detected by the light sensor, the motor is activated which will locate the louvers in the open position. Upon an observable darkened condition being sensed by the light sensor, the motor is activated which will locate the louvers in the closed position. A flow limiter may be used to keep the louvers slightly open when in the closed position to have some heated air enter the room when the ambient temperature is severely cold.

Abstract: An electric control for gas furnaces which controls a two speed main blower fan and an induction draft fan based on inputs from a room thermostat, a high limit and an ignition control including a gas valve. The control has a circuit board having a power supply for providing 24 volts DC current source to drive DC relays and a 5 volt DC power source to power a microprocessor. 24 volt AC input signals are coupled to the input ports of the microprocessor through current limiting resistors and to AC ground through pull down resistors. AC ground is also connected to the IRQ port of the microprocessor. The output ports of the microprocessor are connected to a relay driver which in turn is connected to the relays. Several breakaway tabs in the board provide optional features such as eliminating a normally provided draft delay timing function. Test pads are provided on the board so that the board can be tested during manufacture.