Abstract: A multi-layered hot melt adhesive transfer hose is provided. The transfer hose has a barrier layer that prevents or minimizes the ingress of oxygen and other gases into a conduit of the hose. The transfer hose has at least one structural layer overlaying an exterior surface of the barrier layer to help the hose withstand a high fluid pressure. The barrier layer prevents the hot melt adhesive being transported in the hose from discoloring and charring when the adhesive is heated from about 250° F. up to and including 450° F. for an extended period of time.

Abstract: A multi-layered hot melt adhesive transfer hose is provided. The transfer hose has a barrier layer that prevents or minimizes the ingress of oxygen and other gases into a conduit of the hose. The transfer hose has at least one structural layer overlaying an exterior surface of the barrier layer to help the hose withstand a high fluid pressure. The barrier layer prevents the hot melt adhesive being transported in the hose from discoloring and charring when the adhesive is heated from about 250° F. up to and including 450° F. for an extended period of time.

Abstract: An energy-moving device (EMD) transfers heat between a low-temperature-rated device (LTRD) and a high-temperature-rated device (HTRD), wherein the LTRD is thermally separated from the HTRD such that the LTRD is not stacked above the HTRD. A temperature-controlling device (TCD) actively transfers heat between the LTRD and the EMD. An air-moving device (AMD) generates an air stream for transferring heat from the EMD to ambient air. A controller receives temperature information about the ambient air, the LTRD, and the HTRD; determines when heat should be removed from the LTRD, when heat should be added to the LTRD, and when no heat needs to be transferred to or from the LTRD; and determines a first voltage for the TCD and a second voltage for the AMD based on the received temperature information. And a neural network updates the voltage values based on how effectively the voltage values have performed.

Abstract: A system and method controls a heat transfer system for palletized product. A controller and an array of sensors cooperate to control chillers and fans to efficiently change the temperature of product within the cases, while collecting and providing data regarding the efficacy and overall spatial profile of the freezing or other temperature-control operation. These data can be used to provide user feedback, optimize the temperature-control process, and ensure a desired performance of the system.

Abstract: A method for controlling door motions of a controllable door of a motor vehicle, wherein a control device and a sensor arrangement are assigned to the door, and the door includes a controllable motion influencing device. A motion of a door wing of the door can be controlled and influenced by the motion influencing device to alternate between a closed position and an open position. The sensor arrangement includes a surround sensor and monitors the surroundings of the door. The control device captures the signals from the sensor arrangement and evaluates the movement of an object in the surroundings of the door relative to the door and actively moves the door wing of the door, to prevent a collision with the object or to reduce its effects.

Abstract: A transport refrigeration system (26) includes a transport refrigeration unit (44), an energy storage device (46), a supply refrigerant tube (108), a return refrigerant tube (110) and at least one electrical pathway (98). The transport refrigeration unit is adapted to cool a container. The energy storage device is adapted to provide electrical energy for operating the transport refrigeration unit. The supply refrigerant tube flows a refrigerant from the transport refrigeration unit to the energy storage device, and the return refrigerant tube flows the refrigerant from the energy storage device back to the transport refrigeration unit to cool the battery in the energy storage device (46). The electrical pathway extends between the transport refrigeration unit and the energy storage device, and supplies at least electrical energy to the transport refrigeration unit.

Abstract: A drilling tool includes: a drive source; a bit attachment portion to which an end bit is attachable; a power transmission portion configured to apply a motive force to the end bit attached to the bit attachment portion; an operation portion switchable between an ON-state and an OFF-state by a manual operation and configured to receive a setting operation for setting a stop condition; and a controller configured to set the stop condition based on the setting operation, and to start driving of the drive source in response to a first switching operation for switching the operation portion from the OFF-state to the ON-state. In a state where the stop condition is set, even when the operation portion is in the ON-state, the controller stops driving of the drive source in response to the stop condition being met while the drive source is being driven.

Abstract: A motor driven power steering (MDPS) may include: a vehicle speed sensor configured to sense vehicle speed; a temperature sensor configured to sense a temperature of a power pack; a current sensor configured to sense an amount of current applied to the MDPS; a storage unit configured to store a thermal resistance value based on the vehicle speed with respect to the temperature of the power pack; and a control unit configured to calculate an estimated temperature by reflecting the thermal resistance value based on the vehicle speed with respect to the temperature of the power pack and the current amount applied to the MDPS into a temperature estimation function, and drive a motor according to the calculated estimated temperature.

Abstract: A system to monitor the temperature of power electronic devices in a motor drive includes a base plate defining a planar surface on which the electronic devices and/or circuit boards within the motor drive may be mounted. The power electronic devices are mounted to the base plate through the direct bond copper (DBC). A circuit board is mounted to the base plate which includes a temperature sensor mounted on the circuit board proximate to the power electronic devices. The temperature sensor generates a digital signal corresponding to the temperature measured by the sensor. A copper pad is included between each layer of the circuit board and between the first layer of the circuit board and the sensor. The circuit board also includes vias extending through each layer of the board. The copper pads and vias establish a thermally conductive path between the temperature sensor and the base plate.

Abstract: A computer-implemented fan control method includes measuring a temperature within a computer system and dynamically selecting a fan speed step in response to the temperature received, wherein the fan speed step is selected from a fan speed table defining a finite number of fan speed steps each having an associated fan speed. A fan is operated at the dynamically selected fan speed step, wherein the fan is positioned to drive air through the computer system where the temperature is being measured. The fan output variation is measured over a prescribed time interval and the fan speed table is automatically modified to change the fan speeds associated with each fan speed step, wherein the fan speeds are changed as a function of the measured fan output variation while continuing to drive the fan.

Abstract: A fan system includes: two circuit breakers, a control module for controlling two circuit breakers, two electric motors to which their operating voltage UB is supplied via the circuit breakers, and at least one temperature sensor on a board on which the circuit breakers are located. The control module evaluates a signal TNTC from the temperature sensor, and sets the pulse duty factors TV1, TV2 of pulsed control voltages at the circuit breakers, while taking into account this signal as well as a requested fan power, in such a way that no power loss PV exceeding a specified value occurs at any circuit breaker.

Abstract: A compressor control device includes a driving circuit, for controllably supplying a coil of an electric motor of a compressor. A temperature sensor is thermally coupled to the driving circuit and provides a temperature sensing signal correlated to a temperature in the driving circuit. A control stage, coupled to the driving circuit and to the temperature sensor, selectively prevents the driving circuit from supplying the coil, in response to a minimum temperature increment being detected by the temperature sensor within a pre-determined control time window.

Abstract: An angle calculator determines an angle of a rotor. An angular speed calculator determines an angular speed of the rotor. A command current calculator determines a command current defined on a dq-axis. An open loop controller determines a command voltage defined on the dq-axis in accordance with a circuit equation of a motor, based on the command current and the angular speed. A dq-axis/three-phase converter converts the command voltage into a three-phase command voltage. A resistance calculator and a ?-value calculator respectively determines circuit resistance including armature winding resistance and a number of armature winding linkages which are included in the circuit equation of the motor, based on temperature of the motor detected by a temperature sensor and with reference to a table or the like which is stored in advance.

Abstract: The invention relates to a method and arrangement having an electric machine, comprising a stator (4) and a rotor (1) and an infrared temperature sensor, wherein the detection field of the infrared temperature sensor is directed at an outer surface of the rotor (1). The infrared temperature sensor is a thermopile (6) for radiometrically contactlessly detecting a temperature of the rotor (1), the thermopile being arranged in a slot of the stator (4) and being compatible with standard slot-sealing-wedge components of the electric machine with regard to assembly, and thus enables the operational monitoring of the thermal state of an electric machine in a novel manner, such that adapted power states can be achieved.

Abstract: A rotating speed adjustment circuit for a heat dissipation fan includes a first node, a second node, a reception end for receiving a first control signal, a first resistor coupled to a voltage source and the first node, a second resistor coupled to the first node and the second node, a third resistor coupled to the second node and a ground end, a capacitor coupled to the first node and the ground end, a transistor coupled to the reception end, the second node and the ground end, an oscillator for generating an oscillating signal, and a comparator for comparing a signal of the first node and the oscillating signal, so as to output a second control signal to control a rotating speed of the heat dissipation fan.

Abstract: A fan motor speed control circuit includes: a driving circuit configured to drive a fan motor so as to run at a rotation speed corresponding to a drive signal; a comparison circuit configured to output a comparison signal for matching a rotation speed of the fan motor with a target rotation speed, based on a reference signal corresponding to the target rotation speed of the fan motor and a speed signal corresponding to the rotation speed of the fan motor; and a selection circuit configured to output to the driving circuit the drive signal corresponding to one signal out of the reference signal and the comparison signal, the one signal being a signal by which the fan motor is driven at a higher rotation speed.

Abstract: A system comprising a chassis that includes a plurality of modules and a fan assembly disposed in a distal end of the chassis for drawing air in parallel pathways through the plurality of modules. At least one of the modules is a compute module having a thermal sensor disposed to sense the temperature of air flowing across a processor mounted on a motherboard. The system further comprises a fan controller receiving output from the thermal sensor, wherein the fan controller operates the fan assembly to cool the plurality of modules and maintain the thermal sensor output within an operating temperature range. The fan controller controls the fan speed according to predetermined thermal profile settings associated with one of the compute modules received in the chassis. For example, the predetermined thermal profile settings may include a minimum fan speed, a maximum fan speed, and control loop feedback settings.

Abstract: A motor speed control circuit includes: a voltage generating circuit configured to change either a reference voltage corresponding to a target rotation speed of a motor or a speed voltage corresponding to a rotation speed of the motor, according to a temperature, and output the reference voltage and the speed voltage, either one of which is changed; a comparison circuit configured to compare the speed voltage output from the voltage generating circuit with the reference voltage output from the voltage generating circuit; and a driving circuit configured to drive the motor so as to match a level of the speed voltage to a level of the reference voltage, based on a comparison result from the comparison circuit.

Abstract: Windshield wiper device (10), particularly for a motor vehicle, having at least an electric motor drive (24) is proposed. This comprises an electric motor drive, which can be driven with at least one first speed (V1) and one second speed (V2). According to the invention, a temperature detection means (40) for detecting the operating temperature of the drive (24) and at least one switching means (50) are provided, which, when operating the drive (24) at the second speed (V2), switches the drive (24) from the second speed (V2) to the first speed (V1) when a predetermined operating temperature (T1) is exceeded.

Abstract: The present invention discloses a cooling-fan rotation-speed control circuit, wherein a plurality of sets of input power sources respectively having different voltages is electrically and parallel coupled to a cooling fan; a switch is installed between at least one input power source and the cooling fan; the switch is turned on/off according to a rotation-speed parameter to determine whether the cooling fan is driven by a low-voltage driving power or a high-voltage driving power.

Abstract: A heat dissipation system includes at least one fan, at least two controllers, a signal generator, and a signal converter. The controllers are electrically connected to the fan and generate an enable signal according to a feedback signal of the fan. The signal generator is electrically connected to the controllers and generates a control signal according to the enable signal. The signal converter is electrically connected to the signal generator and the fan, converts the control signal to a drive signal to the fan, thereby controlling rotation speed of the fan.

Abstract: An electric motor controller for a vehicle has a voltage detecting section for detecting the voltage of a filter capacitor inserted on a direct current side of an inverter device including a semiconductor element for large electric power; an electric current detecting section for detecting an output electric current of the inverter device; and a temperature detecting section arranged in a cooling means of the semiconductor element for large electric power. Loss generated by a switching operation of the semiconductor element for large electric power is sequentially calculated by outputs of the detecting sections. Excessive temperature is detected when junction temperature of the large electric power semiconductor element calculated by this loss reaches an allowable temperature.

Abstract: To precisely detect the temperature of a power assist motor without using a temperature sensor and enhance an overheating protection function. A calorific value calculating unit calculates a calorific value based upon the difference between a calorific value by current supplied to a motor and the quantity of heat radiation. The output of the calorific value calculating unit is accumulated and an accumulated value is input to an accumulated value buffer. A cumulative value TS acquired by adding initial temperature T0 to a cumulative value Td is input to a ratio map of a target current value, ratio is read, and a target base current value is limited according to the ratio. The cumulative value TS used in the map is not an actual motor current value and is calculated based upon unlimited current acquired in an unlimited current calculating unit.

Abstract: An apparatus for detecting a type of fan and controlling the fan, the fan providing during operation a tachometer signal indicating a speed of the fan, the apparatus includes: a direct current (DC) generator for coupling to the fan and configured to provide a first voltage to the fan; a resistor for providing, while the DC generator provides the first voltage, a sensed voltage relating to the type of the fan, wherein the resistor is connected to a reference voltage and for coupling to a pulse-width modulation (PWM) control terminal of the fan; an input judgment component coupled to the resistor to receive the sensed voltage, the input judgment component being configured to determine whether the fan is a 4-wire PWM fan with an internal pull-up resistor based on the sensed voltage and to provide a judgment signal indicating the determination; a PWM generator coupled to the input judgment component to receive the judgment signal, the PWM generator being configured to provide to the fan a PWM control signal to co

Abstract: A switch-type power converter comprising an PET switch operating in a variable duty cycle mode under the control of a Unitrode 3846 integrated circuit controller. Indications of excess input voltage and reverse battery connections are provided by circuits including an element which permanently changes state. A cooling fan mounted on a finned heat sink is operated in a variable speed mode. A single thermistor sensor provides inputs to both the fan speed control and a thermal shutdown circuit connected to shut down the gate drives to the FET switch in the event of a high temperature condition. Another shutdown function is provided in response to an input overvoltage condition by way of an operational amplifier. The converter uses foldback for short circuit protection and is compatible with microprocessor units to selectively provide multiple output voltage levels.

Abstract: Kinematic control of an electronic positioner and its associated actuator is effected through a control algorithm that delivers energy to the actuator based on observed motion produced by a previous delivery of energy. The algorithm achieves control based on a desired or user-specified resolution. Electronic braking between energy delivery intervals improves the speed at which the desired position is achieved. Temperature of the force producing mechanism is determined, as by monitoring energy consumed, and used to control how power is delivered to the actuator.

Abstract: The present invention provides an apparatus and a method for accurately detecting abnormal conditions of a motor. A ?Tc/Tj detector detects a difference (?Tc) between an environment temperature and a temperature of a field-effect transistor (FET) which turns on and off electric power supplied to a DC motor. A diagnosis control unit detects abnormal conditions such as a motor lock and a short circuit of the DC motor based upon the obtained difference. When the motor lock has been detected, the diagnosis control unit controls a pulse width modulation (PWM) control unit and a PWM oscillator (PWMOSC) and makes a frequency and duty cycle of a PWM signal lower. When the short circuit has been detected, the diagnosis control unit controls a gate driver and turns off the FET.

Abstract: A disk drive is disclosed including a disk, a head coupled to a distal end of an actuator arm, and a voice coil motor (VCM) operable to rotate the actuator arm about a pivot to actuate the head radially over the disk, wherein the VCM comprises a coil. Control circuitry within the disk drive measures a load resistance of the coil prior to executing a load operation, wherein the load operation moves the actuator arm off a ramp to load the head onto the disk. The load resistance of the coil is then converted into an initial coil temperature estimate.

Abstract: A control device of a fan system includes a temperature sensing module, a comparing module and a driving module. The temperature sensing module senses an external temperature and generates a sensing signal according to the external temperature. The comparing module receives the sensing signal and outputs a comparing signal according to the sensing signal and a reference voltage signal. The driving module, which is electrically connected with the temperature sensing module and the comparing module, supplies a working voltage to the temperature sensing module and the comparing module, and outputs a rotating speed control signal according to the sensing signal or the comparing signal.

Abstract: Methods, apparatus, and articles of manufacture control a device or system that has an operational limit related to the rate or frequency of operation. The frequency of operation is controlled at a variable rate calculated to maximize the system or apparatus performance over a calculated period of time short enough that a controlling factor, such as power consumption, does not vary significantly during the period. Known system parameters, such as thermal resistance and capacitance of an integrated circuit (IC) and its package, and measured values, such as current junction temperature in an IC, are used to calculate a time-dependent frequency of operation for the upcoming time period that results in the best overall performance without exceeding the operational limit, such as the junction temperature.

Abstract: A running pattern of one cycle in a preset industrial machine is observed by a current detector and a temperature rise value estimating unit that are additionally provided in a traditional inverter device. The temperature rise value estimating unit derives a maximum temperature rise estimate value for each constituent element in the case where the running pattern is periodically repeated, on the basis of observation data of the one cycle and a temperature rise model of each constituent element of the inverter device.

Abstract: A printer and a method of driving a cooling fan of the printer include a storage unit temporarily stores printing option data and image data, and a control unit controls an operation of a printing unit in one of a warming-up mode, a standby mode, a printing mode and a sleep mode based on the printing option data and the image data as inputted into the control unit. The control unit outputs a control signal variably controlling an RPM (Rotation Per Minute) of the cooling fan based on the operation mode and a printing speed of the printing unit. A cooling fan driving unit drives the cooling fan at a different RPM based on the control signal input from the control unit. Accordingly, the printer and the method of driving the cooling fan of the printer are capable of shortening the warming-up time to increase an initial printing speed, preventing the printing unit from being overheated, extending a lifespan of the cooling fan, and reducing a power consumption.

Abstract: A circuit for controlling rotational speed of a fan includes a sensor, a first chipset, and a second chipset. The sensor detects an ambient temperature and generates a corresponding temperature signal. The first chipset provides a pulse-width modulation signal to the fan for driving the fan, and receives a rotational speed signal from the fan. The second chipset defines a controlling relationship between the rotational speed of the fan and the temperature. The controlling relationship is that the temperature is partitioned into a plurality of temperature ranges and each of the temperature ranges corresponds to a rotational speed range. The temperature signal is transmitted from the sensor to the second chipset via the first chipset. The second chipset determines a rotational speed range according to the controlling relationship, and controls the first chipset to adjust the pulse-width modulation signal until the actual rotational speed of the fan is in the rotational speed range.

Abstract: An electric drivetrain for a mobile machine is disclosed. The electric drivetrain has at least one power consuming device, a sensor associated with the at least one power consuming device, and a controller in communication with the power consuming device and the sensor. The sensor is configured to generate a signal indicative of a temperature of the power consuming device. The controller is configured to limit a power consumption level of the at least one power consuming device to an amount corresponding to a value of the signal.

Abstract: A fan voltage regulation control device includes a voltage regulation control unit for providing the power to a heat-dispersing fan, wherein the voltage regulation control unit is connected to a temperature detecting element and a voltage detecting unit. The temperature detecting element may influence the output power from the control unit to the fan, and through the voltage detecting unit, an input current to the fan can be maintained for providing overload and overheated protections.

Abstract: A thermal control variable-speed circuit without switching noise is connected with a driving circuit, which controls the rotation speed of a fan motor using a driving voltage. The thermal control variable-speed circuit includes a reference voltage output circuit and a driving voltage control circuit. The reference voltage output circuit outputs a corresponding reference voltage signal according to ambient temperature changes. The reference voltage output circuit has one end connected to a first resistor in series and to a second resistor in parallel. The driving voltage control circuit outputs a corresponding driving voltage according to the magnitude of the reference voltage signal.

Abstract: A power supply with performance display is disclosed. The computer power supply mainly has a power converter, a control module, and a display. The control module receives and processes the operating signals from the power converter, and then sends those processed signals to a display in a numerical value form. The power supply can be applied in a computer, an adapter, or other electronic products, which is convenient for users to know the operating status of the power converter.

Abstract: There are included a control circuit to control sequence of excitation of a stepping motor, a switching circuit to switch electric power to be supplied to the stepping motor based on an instruction from the control circuit, and a stop circuit to stop an operation of the switching circuit in a case where temperature of the switching circuit becomes a specified temperature or higher, and the control circuit controls the switching circuit in a mode where the stop circuit operates before the stepping motor is damaged by heat.

Abstract: An apparatus for the thermal regulation of an AC drive for providing power to a motor includes a temperature sensor producing a signal indicative of temperature, a heater resistor connectable across a DC link of the AC drive, and a first switch. A controller is operable to monitor the temperature signal and control the first switch to provide power via the DC link to the heater resistor if the sensed temperature is below a predetermined setpoint.

Abstract: An air fan rotation speed control method and a structure thereof aim to provide an automatic control mode and a manual control mode at the same time to control rotation speed regulation of an air fan to achieve instant heat dissipation for an environment and reduce temperature rising of the environment efficiently. The present invention has a rotation speed determination mechanism that adopts the higher rotation speed request at a higher priority to regulate the rotation speed of the air fan in either control mode. Hence the temperature of the environment can be reduced at the higher rotation speed.

Abstract: Fan module and control device thereof. The fan module comprises a plurality of fans and the control device. The control device comprises a temperature sensing circuit, and a driving circuit. The temperature sensing circuit detects an ambient temperature of the fans and generates a sensing signal accordingly. The driving circuit is coupled between the fans and temperature sensing circuit, and comprises a fully powered operating mode and a power-saving operating mode, wherein the driving circuit selects different operating modes in accordance with the sensing signal, and generates a fan driving signal controlling the speed of the fans.

Abstract: A system for controlling an electric motor comprises, in one embodiment, an encoder; a central processor in communication with said encoder; a module processor in communication with said central processor; feedback circuitry in communication with said module processor, wherein said encoder is an electronic device that provides rotor and stator positional information to said central processor, and further comprising a user interface in communication with said central processor, wherein said user interface enables a user to select preferred operational parameters for an electric motor. Another embodiment comprises a method for controlling an electric motor, comprising: determining rotor position based on data received from an encoder; determining how to energize stator coils; directing a power module to provide appropriate current to appropriate coils; and monitoring rotor response, wherein determining how to energize stator coils comprises consulting a look-up table.

Abstract: A fan controlling device for a frequency converter, which is applied to a high-power frequency transforming system that installs fans according to the heat dissipating requirements and their switching operation, failure detection and control, and the fan controlling device includes a frequency transformer and a plurality of direct current fans connected to the frequency transforming system, and each fan is installed at a desired position for dissipating heat in a casing of the frequency transformer by locking, sliding tracks, drawing or latching and each fan is connected to a fan controlling device, and a sensor of the fan controlling device detects the temperature of each set temperature point for switching the fans, controlling the operating number and speed of the fans, so as to improve the quantity, position, operability of installed fans as well as reducing the power consumption when the fans are at an idle state.

Abstract: A fan operation adaptive control system is proposed, which is designed for use with an electronic system, such as a network server, for providing the network server with an adaptive operation control function; and which is characterized by the utilization of a CPLD (Complex PLD, where PLD=Programmable Logic Device) module for implementing the adaptive operation control function for various different types of fan units, including PWM-driven type (which includes 100 Hz–500 Hz, 10 KHz–50 KHz, and 1 MHz–5 MHz subtypes) and DC-driven type, such that the network server can be equipped with just one type of temperature sensor which can be used in conjunction with these various different types of fan units. This feature allows the maintenance of heat-dissipating fan units on network servers to be more convenient and cost-effective to implement than the prior art.

Abstract: An electric motor system includes an electric motor, a temperature sensor mounted therein capable of measuring a local temperature and generating a temperature related signal, and a processor configured to calculate an actual temperature of a rotor magnet from the temperature related signal, and an actual output torque from the actual rotor magnet temperature. A method for determining the actual output torque of a motor includes sensing a temperature within the motor, calculating a rotor magnet temperature from the sensed temperature, and calculating the actual output mechanical torciue from the rotor magnet temperature.

Abstract: A single-phase motor driving circuit includes a controller for outputting a control signal to drive a single-phase motor in a period in which a saw-tooth voltage of a predetermined cycle is larger than a duty setting voltage based on a result of comparing a detected temperature voltage changed based on a temperature detected by a temperature detecting device with a starting duty setting voltage increased with time while a voltage smaller than the detected temperature voltage at the time of starting the single-phase motor is set as an initial value. The controller sets the duty setting voltage as the starting duty setting voltage when the result of the comparison shows that the starting duty setting voltage is smaller than the detected temperature voltage, and the duty setting voltage as the detected temperature voltage when the starting duty setting voltage is larger than the detected temperature voltage.

Abstract: Methods, apparatus, and articles of manufacture control a device or system that has an operational limit related to the rate or frequency of operation. The frequency of operation is controlled at a variable rate calculated to maximize the system or apparatus performance over a calculated period of time short enough that a controlling factor, such as power consumption, does not vary significantly during the period. Known system parameters, such as thermal resistance and capacitance of an integrated circuit (IC) and its package, and measured values, such as current junction temperature in an IC, are used to calculate a time-dependent frequency of operation for the upcoming time period that results in the best overall performance without exceeding the operational limit, such as the junction temperature.

Abstract: A method and system for variable speed fan control for thermal management of a device includes disposing a first temperature sensor proximate a variable speed fan to measure an air temperature of inlet air Tair that cools the device by convection air flow. A controller is configured to compensate for changes in Tair by varying a convection coefficient (h) which is a strong function of air velocity to maintain the product of h*?T at a constant value, wherein ?T is a temperature differential between the device (TAD) minus Tair. Thus, h is varied by varying air velocity by varying a speed of the variable speed fan.

Abstract: A fan motor speed control circuit includes a driving circuit, a voltage division circuit, and a speed modulator. The voltage division circuit has a first transistor and a plurality of resistors and is connected between a voltage source and the driving circuit. The speed modulator has a second transistor and a plurality of parallel resistors and is connected between the voltage division circuit and the driving circuit. The current of the fan motor speed control circuit flows through a first path under a first input voltage generated from the voltage source and through a second path under a second input voltage larger than the first one; the parallel resistors are in the second path such that the current value passing through the driving circuit varies according to the resulting resistance value of the parallel resistors.

Abstract: An electric fan temperature-rated variable speed control circuit, includes a D.C. current source and fan activation IC. There are, between the current source positive and negative poles serially connected transistor, regulation tube, with the regulation tube negative pole linked to the current source negative pole, and its positive pole, incorporated to form the primary current. Between triode base and collector lies a serially connected resistor. The triode collector is linked to the current source positive pole, and between its base and collector lies a serially connected rectifying resistor, which bypasses through the base to connect with the fan activation IC for sending out fan rotation speed control signals with which to form a circuit that adopts a straightforward, easy-to-implement method that offers low-cost and dependable temperature-control characteristics.