Abstract: A controller for a variable air volume terminal of a variable air volume air conditioning system which comprises a temperature sensing circuitry for generating a temperature process value, a setpoint determining circuitry for establishing a temperature setpoint, an airflow signal circuitry for generating an airflow setpoint in response to the temperature process value and the temperature setpoint. A flow sensing circuitry for generating a flow process value in response to a predetermined set of flow sensing inputs and damper control circuitry for generating a damper motor operation signal to control the damper motor in response to the flow process value and the airflow setpoint. The damper control circuitry comprises a fuzzy logic control mechanism for implementing a set of fuzzy logic rule-based instructions in generating the damper motor operating signal.

Abstract: An air conditioning apparatus by which the air conditioning apparatus is controlled with optimal respondency and stability so as to enjoy indoor-space comfortability. The air conditioning apparatus for use with cycle dry, includes: an outdoor heat exchanger; a fan unit for blowing air to the outdoor heat exchanger; an adjusting portion, connected to the outdoor heat exchanger, for adjusting flow rate of refrigerant; a first indoor heat exchanger and a second heat exchanger connected to the adjusting means; a compressor which is connected both to the indoor heat exchanger and the outdoor heat exchanger, and which is controllable by an inverter unit; a detecting portion for detecting temperature and humidity indoors; and a cross control system for determining rotation frequencies of the fan unit and the inverter unit by comparing data obtained from the detecting portion with predetermined values of temperature and humidity indoors.

Abstract: A method of controlling the capacity of a chiller system, the chiller system including a circularly linked compressor, condenser, expansion device, and evaporator. The method comprises the steps of: measuring a first chiller system parameter; determining a first parameter error as a function of the difference between the first parameter and a first setpoint; measuring a second chiller system parameter; determining a second parameter error as a function of the difference between the second parameter and a second setpoint; providing a first mode of capacity control where the compressor is modulated in response to the first parameter error and the expansion valve is modulated in response to the second parameter error; and providing a second mode of capacity control where the compressor is maintained at a minimum capacity and the expansion valve is modulated in response to the first parameter error.

Abstract: A thermostat and method for controlling the overshoot and undershoot of the temperature in a zone that are caused by an air conditioning system responsive to a change in the setpoint of the thermostat is disclosed. The thermostat includes a sensor for detecting the temperature in the zone and being adapted to generate a signal representative of the temperature. A processor for controlling the air conditioning system is communicatively coupled to the sensor and receives the signal representative of the temperature of the zone therefrom. A setpoint input device for changing the setpoint of the thermostat is communicatively coupled to the processor and is adapted to provide a signal representative of the changed setpoint to the processor. The processor controls the air conditioning system in a static condition mode during normal operations and switches the air conditioning system to a full on mode responsive to a setpoint change.

Abstract: In a control apparatus of an air-conditioner in which a temperature difference between the room temperature and the set temperature is set into an input 1, a time-dependent change in the room temperature is set to an input 2, fuzzy arithmetic operations are executed in accordance with control rules by using membership functions of a membership function section 1, a switching amount of an operating frequency of a compressor 2 of an output is controlled on the basis of the results of the fuzzy arithmetic operations, and the operating frequency is switched at every predetermined interval (t seconds) thereby executing a room temperature control, during the operation, a room temperature (Tr) is always detected by a room temperature detecting section 4 and a change amount (Tr2-Tr1) of the room temperature is calculated in a room temperature change amount calculating section 5 each time of the detection, and when the calculated change amount exceeds a predetermined value, it is determined that the room temperature s

Abstract: A temperature control apparatus and method which utilizes a characteristic of a temperature detection device which detects temperature over a wide range of changing temperature and makes it possible to control a unit by detecting a wide range of changing temperature of the unit using the single temperature detection device. A temperature detection circuit outputs a voltage corresponding to the resistance value of the temperature detection device, whose resistance value varies with changes in temperature, which voltage is A/D (analog-to-digital) converted into a digital step value. This digital step value is converted to a temperature value using a predetermined mathematical relationship. The temperature control is executed using the converted temperature value and a desired temperature value in the same data form as the converted temperature value.

Abstract: A controller for controlling an air conditioner comprises a room temperature sensor for measuring a room temperature, a room temperature change computation circuit for computing a difference between the room temperature and a set temperature, an outdoor temperature sensor for measuring an outdoor temperature, a neural network for computing load on the air conditioner according to the temperature change, outdoor temperature, and room temperature, and a controller for controlling, according to the computed load, the operation frequency of a coolant compressor by controlling a compressor motor through a variable frequency circuit, thereby speedily bringing the room temperature to the set temperature and stably maintaining the room temperature at the set temperature. The neural network learns various operation characteristics of a refrigerating cycle of the air conditioner, and according to a result of the learning, controls the air conditioner.

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: A temperature control device with high accuracy and stability comprising a heating device and a cooling device which are controlled by separate control circuits for performing proportional control, integral control, derivative control and the like. A ratio of energy supply periods to predetermined control periods is thereby varied, on the basis of a controlled variable calculated from direction, size, change velocity and the like of deviation of actual temperature of a controlled medium from desired set temperature so as to control heating and cooling energy supplies for the heating and cooling devices. The heating energy and cooling energy supplies for the heating and cooling devices can be separately controlled by means of different proportional bands.

Abstract: A computer-controlled automotive air conditioning system comprises an air conditioning unit which, when operated, produces a conditioned air fed to a passenger room of the vehicle. An outside temperature sensor, an inside temperature sensor, a temperature setter switch, a solar radiation sensor and an intake air temperature sensor are arranged for issuing first, second, third, fourth and fifth information signals. A computer-installed control unit is employed for controlling operation of the air conditioning unit in accordance with the first, second, third, fourth and fifth information signals. The computer is operated under a fuzzy system theory so that the magnitude of at least one of the first, second, third, fourth and fifth information signals is divided into a predetermined number of fuzzy labels of membership function to derive a parameter for operation of the air conditioning unit.

Abstract: The present invention is directed to a control apparatus for use in an automotive air conditioning system which includes a variable capacity-type refrigerant compressor. The automotive air conditioning system comprises a refrigerant circuit including a refrigerant compressor with an externally controlled, variable capacity control mechanism; an evaporator connected to a suction chamber of the compressor; and a control apparatus which controls refrigerant circuit operation. The control apparatus includes an adjusting device for adjusting a control point of the compressor suction chamber pressure. During operation of the automotive air conditioning system, the control point of the compressor suction chamber pressure is adjusted to effectively maintain the temperature of air immediately downstream from the evaporator at the set temperature.

Abstract: A cooling apparatus has a heat exchanger for performing heat exchange between cooling water and fluid, and a flow rate regulator valve for regulating a flow rate of either the cooling water or the fluid which pass through the heat exchanger. A cooling temperature of the fluid is preset. A temperature of the cooled fluid is detected, and an opening degree of the flow rate regulator valve is changed when there is a difference between the detected temperature and the preset temperature. Simultaneously, either a temperature difference of the cooling water and the fluid or a flow rate of the cooling water is detected. The opening degree of the flow rate regulator valve is corrected or compensated on the basis of a result of the detection, thus enabling suitable temperature control of the fluid in accordance with a variation of the temperature or flow rate of the cooling water.

Abstract: A cooling/heating apparatus having an automatic ventilating function and its method switches the ventilating function and the cooling/heating function in response to the pollution state of room air and maintains the room air in a pleasant state. The apparatus and method rotates the cooling/heating fan and the ventilating fan to be mutually supplemented and completed by the output of a gas sensor which changes its resistance value in response to the air pollution state within a room. The ventilating fan is rotated instead of said cooling/heating fan when the room air is polluted and ventilates the polluted air within a room.

Abstract: An air heating apparatus such as a fan heater, a forced circulation type ware air heater, and, an air conditioner and heater, is operated while the amount of radiation is taken into consideration. Moreover, after a PMV value of the room to be heated is generated from the temperature, amount of radiation, etc. of the room to be heated, the burning amount, air flow and the like are controlled to make the PMV value 0.

Abstract: An adaptive aircraft cabin pressure control system is disclosed that customizes basic ascent and descent schedules to accommodate variable requirements of specific airlines, the airlines' route structures, and regional air traffic control standards. The system includes an adaptive control logic that identifies a plurality of points generated by the schedules that define ascent and descent curves corresponding to anticipated cabin pressure change rates during ascent and descent. During aircraft flight, the logic samples and stores actual cabin pressure change rates at each of the plurality of points. After the flight, the actual cabin pressure change rates are averaged and the average rate is compared to the anticipated cabin pressure change rate at each point.

Abstract: A refrigerating apparatus which is capable of accurate and swift correspondence to a transient change of a refrigerant circuit or an accumulated deviation of the degree of superheat of a refrigerant, thereby releasing the state in which the liquid refrigerant is flowing back to the compressor and the overheated state, and a method of controlling such a refrigerating apparatus. The refrigerating apparatus comprises a refrigerant circuit composed of a condenser, an expansion valve and an evaporator which are connected to each other in series, a means for detecting the evaporating temperature of the refrigerant, a means for detecting the exit temperature of the evaporator, and a control means for controlling the opening of the expansion valve on the basis of the evaporating temperature of the refrigerant and the exit temperature of the evaporator in accordance with a fuzzy reasoning.

Abstract: A multi-system air conditioner comprises an exterior unit including a compressor and a plurality of interior units, each being installed in a room and including a heat exchanger and an expansion valve therefor. An opening degree of the expansion valve in an interior unit is controlled based on not only the superheat degree of the compressor but also the room temperature difference. Further, the control based on the superheat degree is carried out by means of the fuzzy logical calculation on superheat degree value. A rotational speed of the compressor is controlled based on not only the load capacity of the room but also the room temperature difference. Further, a control based on the fuzzy logical calculation on the pressure value is added. A feed forward control is also added so as to shorten the transient time.

Abstract: A space temperature control which prevents overshoot and undershoot of a desired space temperature by adjusting a subsequent sensed space temperature as a function of a previous sensed maximum space temperature to deenergize a space conditioning device at the adjusted temperature to maintain the desired space temperature.

Abstract: A system for controlling vehicle passenger compartment comfort. An electronic controller receives input from: (i) a thermistor array sensing blower plenum discharge temperature, (ii) a user movable Level Select Control (iii) a potentiometer sensing the position of a servo driven heater core water valve, (iv) an engine rpm tachometer generator and (v) a blower speed signal. The controller drives the servomotor for the water valve at a "High" rate until the valve position potentiometer indicates that the valve is within fifteen degrees (15.degree.) of the target, whereupon the controller drives the servomotor at a "Low" speed.

Abstract: There is disclosed a temperature control system for an absorption refrigerating apparatus comprising an evaporator, an absorber, a condenser, a regenerator, a solution heat exchanger, a solution pump, a cooling medium pump, and piping operatively connecting these parts together. Where absorption refrigerating machines are arranged in two or more stages with respect to the flow of cold water to be circulated at a load side, the machine of each stage has a cold water outlet temperature detector, and a temperature controller for controlling the amount of heat of a machine-driving heated fluid in accordance with the cold water outlet temperature of each stage. A control circuit is so arranged that the temperature controller of the first stage, or the temperature controllers of the intermediate stages except for the temperature controller of the final stage are controlled by a proportional control whereas the temperature controller of the final stage is controlled by a PID control.

Abstract: A process of operating an electronic thermostat so that it models the effects of a mechanical thermostat anticipator.

Abstract: Apparatus for and method of long-term control of the temperature within a refrigerated space, such as the cargo compartment of a refrigeration truck. The technique employs sensors which monitor both discharge and return air. A control algorithm uses the multiple sensors to control modes of a refrigeration unit capable of supplying cooled or heated air. This causes the temperature within the refrigerated space to remain within a narrow range about a target temperature. The target is chosen to provide maximum safety for the cargo. If the target temperature is too high, the cargo is needlessly exposed to spoilage. If the target temperature is too low, the cargo is subject to the risk of damage from freezing.

Abstract: A controller having two cascaded PID control loops in the control of unit ventilators of the type which have a heating coil, a fan, and a damper for admitting outside air into a room in which the unit ventilator is located. The controller utilizes the sensed room temperature and a room temperature set point to generate a set point for the temperature of the air being discharged from the unit ventilator, and utilizes the discharge temperature set point and the sensed discharge temperature to control the damper position and the operation of the heating coils of the unit ventilator.

Abstract: A method of operating a transport refrigeration system having a refrigerant compressor driven by a prime mover. Electrical control maintains the temperature of a load in a conditioned space close to a desired set point via heating, cooling and null cycles, with the prime mover being started and stopped, as required, in response to the difference between the temperature of the conditioned space and a selected set point temperature, i.e., temperature error. Restarting of the prime mover is dynamically controlled by controlling the magnitude of the restart temperature error in response to the difference between the temperature of the conditioned space and ambient temperature.

Abstract: A refrigerating system including a refrigerant circuit having a condenser, evaporator and wobble plate type compressor with a variable displacement mechanism. Two passages communicate between the crank chamber and the suction chamber in the cylinder block. A bellows is disposed in a first passage and controls the communication between the crank chamber and the suction chamber response to crank chamber pressure. A control valve is disposed in the second passage and controls communication between the crank chamber and the suction chamber in the second passage in response to a signal generated outside of the compressor. A control circuit controls the generation of the signal in response to thermodynamic characteristics related to the evaporator. The signal activates or deactivates the second control valve when the characteristic indicates a value beyond a predetermined range of values.

Abstract: An automatic air conditioner for a vehicle comprising a cooling unit, heater and a blower fan which are controlled by a control circuit. The air conditioner is arranged to adjust a compartment temperature to a target value set by a target value setting means. Furthermore, the air conditioner has functions such as a quick cooling, a quick heating and a low water-temperature drive control to quickly adjust the compartment temperature to the target value. The air conditioner further includes a function wherein the change of the preset target value is forbidden in operation of the quick cooling, the quick heating and the low water-temperature drive controls to prevent the compartment from being over-cooled or over-heated by the change of the target value in the operation.

Abstract: A control device for an absorption refrigerator which forms a refrigeration cycle by connecting an evaporator, an absorption unit, a generator, a condenser and the like to control a heating amount of the generator. Singular or plural amounts of change representative of externasl conditions are detected. A heating amount of the generator is controlled by a fuzzy logic calculation.

Abstract: The control system for the air-conditioner disclosed herein comprises means for setting a set value of a room temperature, means for detecting an actual value of the room temperature, means for detecting a radiant heat from walls etc. of the room as a radiation temperature, and an operational control means. The operational control means stores a comfort line which defines an inverse proportional relation between the room temperature and the radiation temperature, said comfort line depending upon set value of the room temperature. The operational control means calculates a first control index which is represented by a difference between the actual value and the set value of the room temperature and a second control index which is represented by a difference between the comfort line and the current temperature condition represented by the actual room temperature and the radiation temperature.

Abstract: In an air conditioner including a variable-capacity compressor, a control system performs a PI calculation based on a temperature deviation between the actual temperature of the air downstream of an evaporator and its target temperature, thereby determining a control amount for controlling the capacity of the compressor. It is judged whether or not the sum of a proportional control component and an integral control component exceeds a limit value of the control amount corresponding to the maximum capacity of the compressor. If this judgment is in the affirmative, an ordinary integral calculation is stopped, and the integral control component is determined by subtracting the proportional control component from this limit value.

Abstract: A system for controlling vehicle passenger compartment comfort. An electronic controller receives input from: (i) a thermistor array sensing blower plenum discharge temperature, (ii) a user movable Level Select Control (iii) a potentiometer sensing the position of a servo driven heater core water valve, (iv) an engine rpm tachometer generator and (v) a blower speed signal. The controller employs proportional-integral-derivative (PID) strategy in a microprocessor to generate a control signal for operating the heater core valve servo motor to maintain the plenum discharge air at a constant temperature irrespective of wide swings in engine rpm/water pump speed or user selector changes in blower speed.

Abstract: A temperature control system has a thermostat which provides an on/off signal. The on/off signal has an on period and an off period and is indicative of a temperature error. The temperature control system is suitable for controlling temperature control equipment. The on/off signal is sensed and the temperature error is determined based on the on/off signal. The temperature control system is controlled based on the temperature error determined.

Abstract: An electronic oven temperature regulator employing a comparator to control energization of a relay for cycling the oven heating unit (gas or electric) in response to comparison of an oven temperature sensor output and a user selected reference temperature about which regulation is desired. A reversible polarity voltage regulator provides feedback from the comparator output to the input to provide a positive and negative hysteresis dead band about the selected regulation temperature for minimizing cycling or "hunting" of the heating unit. A fault comparator tracks the selected reference temperature to disable the heating element relay in the event of a short in the temperature sensor.

Abstract: A heating system with a hot water coil is provided with a variable speed blower whose speed is regulated in response to a sensed load in the system. Heat can therefore be added to the hot water by way of a simple burner system, with the required control being effected by selectively varying the amount of heat that is removed from the hot water by controlling the fan speed. When applied to a zone controlled system, the need for a bypass duct is obviated.

Abstract: A control method for a variable capacity automotive air conditioning compressor in which the compressor operating point is tailored to the nonlinear control characteristics of variable displacement compressors. When the error between the desired and actual values of a specified system parameter is relatively large, the operating point is determined by a coarse gain closed-loop control. When the error is within a fine control range defined in relation to the desired value, the control point is set to one of three predetermined values for effecting small displacement increases, small displacement decreases, or no change in displacement. An adaptive tuning technique is used to update the predetermined control point values to compensate for compressor-to-compressor differences and changes in the operating conditions of a given compressor system. An anticipation technique shortens the transition from coarse control to fine control by minimizing gross overshoots of the specified system parameter.

Abstract: Temperature controlling means for a thermostat for use in viscosity measurement including: a first thermometer detecting the temperature of a fluid sample which is immersed in a thermostat and whose viscosity is measured; a first controller obtaining the difference between a desired set point and the detected value of the sample temperature, momently calculating a set point of temperature of the thermostat according to an operation formula expresed as a function of the above temperature difference and making a controlled signal corresponding to the calculated set point; a second thermometer detecting the temperature of the thermostat; a heating and cooling device for heating and cooling a medium bath of the thermostat; and a second controller making a controlled signal for operating the heating and cooling device under a PID control formed on the basis of the difference between the calculated set point and the detected value of the thermostat temperature and inputting the PID controlled signal into the heatin

Abstract: A thermostat is disclosed which includes a Proportional-Integral-Derivative (PID) controller and a means for disabling the PID controller for selected periods. The PID controller is disabled during a temperature recovery period, which can be triggered by the occurrence of one or more of many preselected events. The PID controller is re-enabled when the thermostat setpoint less a void offset temperature is reached. To reduce error in future temperature recovery periods, the void offset temperature is adjusted after a temperature recovery by adding the amount of error to the void offset temperature to create a new void offset temperature for use in a next temperature recovery period.

Abstract: A refrigerating circuit apparatus comprises a variable capacity compressor for compressing refrigerant, an inverter circuit for supplying a variable output frequency to the compressor, a memory for storing data representing at least two different control modes including a first mode wherein the output frequency of the inverter circuit is changed at one frequency changing rate until the difference between the actual pressure value of refrigerant flowing into the compressor and a set value is minimum and a second mode wherein the output frequency of the inverter circuit is changed at a different frequency changing rate until the difference between the actual pressure value of refrigerant flowing into the compressor and the set value is minimum, a select switch for selecting either first or second mode stored in the memory and a control circuit for varying the output frequency of the inverter circuit based on the selected mode to control the rotation speed of the compressor.

Abstract: A method and apparatus control firing rate in a heating system to compensate for thermal mass characteristics of the heating system. The thermal mass characteristics of the heating system are derived from heating system identification information. A weighted control response factor is selected which is representative of load characteristics of a load type affecting firing rate control and which is representative of desired control tightness. The firing rate is varied, based on the weighted control response factor and the thermal characteristics, to match the heating system, the load type being controlled and the desired control tightness for optimum control.

Abstract: With a process for setting the temperature difference between cut-in temperature and cut-out temperature of a heating unit or, in particular, of a refrigerating unit in the region of a set value, to be maintained, of the temperature of a medium or of a room, for automatic adaptation of the temperature difference between cut-in temperature and cut-out temperature to changing loads, the temperature which, starting from the set value, is reached by the unit below or above the set value after expiry of a preselected unit of time in each case being established repeatedly, whereupon these established temperatures are compared and that temperature which coincides with several previously measured temperatures is used for setting the temperature difference between cut-in temperature and cut-out temperature.

Abstract: A control apparatus for controlling the temperature of an environmental chamber within which a device is tested for thermal characteristics employs a pair of control elements connected in cascade. The first element produces a required air temperature in response to a desired temperature and to the temperature of the device; the second produces a temperature set point in response to the required and actual air temperatures. Possible stress on the device is avoided by limiting the range of required air temperature. Response is accelerated by a pass-through circuit, parallel to the first element, which responds to a change in the desired temperature by adding to the required air temperature of value proportional to the change.

Abstract: A method of controlling a refrigeration system by determining an average air temperature by sensing and averaging evaporator return and discharge air temperatures, and developing an average error by using the average air temperature and a selected set point temperature. The average air temperature is then used to calculate a proportional error and an integral error, and the discharge air temperature is used to calculate a floor error. The proportional error, integral error and floor error are weighted by predetermined gain factors and then summed to provide an error signal which is used to modulate the capacity of the refrigeration system, with the control mode depending upon the location of the error signal relative to set point.

Abstract: A system for controlling temperature of air to be discharged into a cabin of a vehicle in an automatically controlled air conditioner system of an automotive vehicle. The air conditioner system is provided with a cooling unit and a heating unit for cooling and heating conditioning air in the air conditioner system for delivery to the cabin of the vehicle. The air conditioner system includes a mechanism for mixing the cooling air and the heating air in a stepwise manner so as to generate a controlled temperature of conditioning air to be discharged into the vehicle cabin with a moderate adjustment in transition so as to maintain a desired vehicle cabin temperature.

Abstract: A system having a microprocessor to provide an adjustable control of the temperature and pressure of water at the outlet of a single adjustable valve. The water temperature at the valve outlet is constantly monitored. A processor compares the actual water temperature with a specifically requested temperature for the water at the valve outlet, and provides signals to relays and a control circuit for a motor which adjusts the temperature of water by the relative proportions of hot and cold water discharged through the valving to the outlet. The system with the microprocessor provides a multi-speed control of the motor having variations in the speed of adjustment of the valve so as to effect a quick valve movement to a temperature in the vicinity of the desired temperature after which fine tuning provides the exactly requested temperature.

Abstract: A temperature-adjustable water supply system used for supplying an appropriate temperature water to a water-using object. The system comprises a mixing device coupled to a hot water supply passage and a cold water supply passage for respectively introducing hot water and cold water thereinto and coupled to a water mixture supply passage for supplying the mixture of the hot water and cold water toward said water-using object. The mixing device includes a flow rate adjusting valve assembly for adjusting the mixture ratio of the hot water and the cold water discharged into the water mixture supply passage. A temperature sensor is provided so as to sense the temperature of the water mixture and a temperature setter for setting a target temperature. Also included in the system is a control unit which calculates a temperature deviation on the basis of the temperature of the mixture sensed by the temperature sensor and the target temperature set by the temperature setter.

Abstract: The air conditioner comprises a manual or automatic sensible temperature detection decision means consisting of a temperature detector for detecting room temperature, a hot/cold selector switch, a radiant heat detector, an air current detector and an outdoor temperature detector, an analog/digital signal converter, a microcomputer, a compressor and a blower, which is characterized in that temperature can be set to a thermal sense of a user, room temperature is automatically regulated step by step to coincide with the set temperature, or a sensible temperature is set automatically by the temperature detection and setting function and thus kept constant at all times.

Abstract: A refrigeration system comprises a compressor, a condenser, an evaporator, an accumulator, and an adjustable controllable expansion valve. An electronic control system monitors the value of superheat and accordingly provides an electrical control signal to adjust the controllable expansion valve in order to maintain a set point superheat value. An unfiltered path is provided to ensure expedient response when the system starts operation and when dynamic changes occur. A filtered path is provided to reduce hunting, or oscillations about the set point, of the superheat value during steady state operation.

Abstract: A boiler control system utilizing a microcomputer, a memory, and a firing rate control scheme provides a boiler with a more responsive control arrangement. This improved response is accomplished by the firing rate control converting the desired pressure setpoint to a computed temperature, and then establishing a computed pressure band for control of the boiler.

Abstract: A thermostat construction for controlling the output effect of a heat exchanger means, a system utilizing such a construction and a method of making such a construction are provided, the thermostat construction having a unit for sensing room temperature that is the result of the output effect, having a set-point unit for selecting a desired room temperature to be provided by the heat exchanger, having a changing unit for changing the effective set-point setting of the set-point unit to change the duty-cycle of the heat exchanger, and having a unit for sensing the current duty-cycle of the heat exchanger and for causing the changing unit to change the effective set-point setting to a different temperature setting thereof as the duty-cycle approaches a peak duty-cycle of the heat exchanger so that the current duty-cycles is reduced.

Abstract: In a technological process two liquids are available for heating purposes, of which the warmer one is to be chosen. For this purpose, the temperature of the two liquids is measured and the flow of the two liquids is controlled as a function of the temperatures by means of actuators. This control is carried out such that at a temperature of the colder liquid which is much lower than the temperature of the warmer liquid, the latter flow is utilized. When the temperature of the colder liquid approaches the temperature of the warmer liquid, the actuator for the colder liquid is slowly opened. In the case of equal liquid temperatures, both actuators are fully opened. If the temperature of the former colder liquid exceeds that of the former warmer liquid, the actuator of the formerly warmer liquid is slowly closed, while the actuator of the formerly colder liquid remains fully open. Sudden large temperature variances of the heating liquid are thereby avoided.

Abstract: The present invention performs analog to digital conversion using the system clock of a microprocessor, the system clock being the clock which controls the rate of operation of the microprocessor. A varying analog signal is applied to the clock frequency control input of the microprocessor, thereby causing the clock frequency and the rate of operation of the microprocessor to vary in accordance with the varying analog signal. The clock is counted for a predetermined period of time. In the preferred embodiment this predetermined period of time is set by the 60 Hz AC power line. The counted contents at the end of this predetermined period of time is a digital representation of the varying analog signal. The microprocessor includes circuits for performing other operations at the rate set by the clock frequency. The other operations performed by the microprocessor must not be deleteriously affected by the varying rate of operation caused by the varying analog signal.