Abstract: Method and apparatus are disclosed for checking the responsiveness of a circuit which senses the presence of a flame produced by a burner within a furnace. A programmed processor associated with the circuit measures the time the circuit takes to indicate the presence of a flame. A warning is generated when the measured time exceeds a predetermined allowable time. The allowable time is determined by taking into account the decreased responsiveness of an electrode that indicates the presence of the burner flame.

Abstract: A circuit arrangement for flame detection for a transistor coil ignition system of a burner is disclosed. The transistor coil ignition system features a trigger stage which triggers a power transistor that is located in the power circuit of the primary winding of an ignition coil in order to charge the primary winding of the ignition coil with a charging current from a power supply. A circuit arrangement includes a switch having an ignition position and a flame detection position which in the flame detection position restricts the charging current flowing via the primary winding of the ignition coil to an intensity that lies below the charging current intensity needed to generate an ignition spark in the ignition position, so that ignition spark-over cannot take place without a flame.

Abstract: An electric control is shown for gas furnaces which controls fan motors and ignition controls based on inputs from a room thermostat (32), a high limit control and an ignition control (14) including a gas valve. A flame sense circuit (42, 42') is coupled to a microprocessor (U2) and includes a flameprobe (P1) energized by line power through a capacitor (C3) via a quick connect (QC31). A capacitor (C4) is charged by a 5 volt DC source through resistor (R12) and inputted to an inverter (U3, S2) which provides a low signal to the microprocessor when no flame is present. When a flame is present the capacitor (C4) discharges through the flame causing the inverter to change state providing a high to the microprocessor indicating that a flame is present. A diagnostic network comprising a low leakage diode (CR10) and serially connected resistor (R11) is coupled between the microprocessor (pin 8) and the input of the inverter (U3) so that the operation of the flame sense circuit can be tested.

Abstract: A primary control unit and ignitor using a microprocessor for fuel and ignition control and intelligent flame monitoring of a fuel burning device such as kerosene fired heaters. The control unit will function with a voltage supply ranging from 30 to 264 volts, 50 or 60 hertz. It has intermittent ignition resulting in reduced electromagnetic interference and longer spark plug life. The ignitor circuit is isolated from the DC power supply to prevent any common mode electromagnetic interference.

Abstract: A circuit for producing signals representative of at least two flame current levels is disclosed herein. The circuit includes two electrodes locatable in a flame, where a voltage potential is set up between the electrodes, and the current flow is measured therebetween (flame current). The circuit includes an amplifying portion for amplifying the flame current and applying a signal to a microprocessor. The microprocessor samples the signal and outputs a signal representative of the flame current level.

Abstract: Disclosed is an electronic control system for controlling the operation of an oil burner heating system. The control system comprises a relay circuit having first and second relays. When the relays are closed, an external power source is connected to an igniter and motor. The control system also comprises a relay contact monitor configured to detect whether the relays contacts are welded. The control system also comprises a relay control circuit adapted to energize the relays in response to the call for heat from the thermostat and a signal from the relay contact monitor indicative that the relay contacts are not welded. The relays are configured such that only one relay will open or close with power across its contacts. The control system further comprises an improved flame sense monitor adapted to quickly output signals indicative of flame or no flame when such conditions are present with sensitivity hysteresis and a feature to adjust such hysteresis.

Abstract: A burner control system periodically tests for and detects an out of range signal level from a flame sensor in the burner. When the system is in standby operation where no flame is present, the control system checks whether the flame signal level is within an abnormal range defined by a low margin level and a threshold level. When the system is in an operational phase where flame is expected, the system checks whether the flame signal level is within an abnormal range defined by a high margin level and the threshold level. Should either check detect the flame signal within an abnormal range, a signal is provided indicating this abnormal condition. Preferably, the abnormal condition is used to control the flashing of an indicator light, fast during standby phase if the flame signal level is too close to the threshold level and more slowly if the flame signal level is too close to the threshold level while flame is present. It is also possible to use two different lights for the indicators.

Abstract: A heating system controller is suitable for controlling a heating system based on a plurality of sensed control signals representing control parameters. The heating system controller has a first input suitable for being coupled to provide a control signal. The heating system controller also includes a sensor, coupled to the first input, for sensing control signals at the first input, the control signals having a first pattern, a second pattern, or a third pattern detected over at least two successive time periods. The heating system controller includes a control mechanism, coupled to the sensor for controlling the heating system based on the first, second and third patterns. The control mechanism causes the controller to change modes when the third pattern is sensed.

Abstract: A digital control system, for a gas-fired, forced combustion air heating appliance, controls operation of a combustion air blower and a gas valve as a function of essentially square wave input signals derived from a thermostat, a combustion air proving sensor switch, and a gas valve control relay. When a first input signal from the thermostat demands heat, the control system first checks for the presence of a second input signal (which indicates the status of the combustion air sensor switch) before starting the combustion air blower. If the second input signal indicates that combustion air is being delivered before the combustion air blower has started, the control system immediately halts the ignition sequence. If the combustion air sensor switch is functioning properly, the ignition sequence continues and the control system checks a third input signal to determine the status of the contacts of the gas valve relay.

Abstract: A control system, for a gas-fired, forced combustion air heating appliance, controls operation of a combustion air blower and a gas valve as a function of signals from a thermostat, a combustion air proving sensor switch, and a gas valve control relay. When the thermostat demands heat, the control system first checks the status of the combustion air sensor switch before starting the combustion air blower. If the combustion air sensor switch indicates that combustion air is being delivered before the combustion air blower has started, the control system immediately halts the ignition sequence. If the combustion air sensor switch is functioning properly, the ignition sequence continues and the control system checks the status of the contacts of the gas valve relay.

Abstract: A monitor system for safety critical situations such as burner control receives at inputs 17-21 control information from a programmable logic control and reference information at inputs 12-16 from plant interlocks. This information passes via opto-isolators 40 and buffers 41 to the address bus of an EPROM so as to access information stored therein which normally mirrors the PLC information so as to control relays RL1-5 via drivers 45 to conform to the PLC instructions. The EPROM also contains reset and clock information for use by a counter 48 which allows different areas within the EPROM to be accessed. The reset information is also available to a parity check circuit 49 via oscillator 46 for dynamically testing the monitor for integrity of operation. Failure of the PLC or monitor components will cause access to shutdown addresses of the EPROM and operation of the appropriate relays including lockout relay RL6.

Abstract: A method and circuit for self-checking problems in a heating system for an automobile are disclosed. A self-checking and indicating process are disclosed which include a first preheating step; an ignition period; a second preheating step; a combustion period module; and an extinguishment step according to a program interrupt. Various checking steps are included, along with various subroutines for indicating errors. Errors are displayed and a stopping step is performed if the temperature checked and the various proceding checking steps indicate that error conditions exist. The present invention includes an indicating apparatus which includes an output part of a microprocessor which provides a fundamental memory, a data processor, an arithmetic and logic accumulation, and an interrupt. The microprocessor is connected to an output part of a driving apparatus, and a sensing part which senses the driving state of the output part, the ignition, the temperature, and a low voltage condition.

Abstract: Flame monitoring is normally performed in a space heater for a motor vehicle in order to stop the fuel supply within a certain period of time in the case of interruption of the flame. If interruption of the flame is detected by measuring the temperature on the heat exchanger or the combustion chamber of the heater in order to detect a possibly relatively rapid temperature drop, it must be ensured that the temperature at the test point can indeed decrease rapidly enough. It is therefore necessary constantly to monitor the electric motor of the blower for the combustion air or for the heating air flowing past the heat exchanger, so that the combustion chamber or the heat exchanger will indeed cool after interruption of the flame. The operation of the blower motor is monitored by briefly interrupting the power supply and measuring the generator voltage generated by the motor that continues to rotate. If there is no generator voltage or it is too low, a malfunction indication is generated.

Abstract: A fuel burner includes an electrical igniter which lights a pilot burner which then lights the main burner. Operation of each of these steps is monitored, and if any are improper, the control device reverts to lighting the pilot burner with the main burner valve shut. If the igniter is sensed as incapable of lighting the pilot burner, the pilot burner valve is shut, and an error is indicated to the operator.

Abstract: A microcontroller and system allowing for more than one trial time in a furnace system, while using only one pin of the microcontroller. An alternating current signal at an input port of the microcontroller causes the microcontroller to allow a first long trial time period. Any direct current signal at the input port causes the microcontroller to allow only a second shorter trial time period. The trial time input port of the microcontroller is placed between two ports which either receive or send direct current signals. Due to this arrangement of the parts and construction of the microcontroller, the microcontroller will fail to the shorter and safer trial time if a fault causes an erroneous signal to appear at the input port.

Abstract: An optical fire detection system that uses cosmic radiation or a radioactive source to test whether the ultraviolet light detector tube operates properly and includes self test logic to independently verify that the detector electronics are functioning properly. A high voltage is applied across the ultraviolet light detector tube to produce pulses of current when radiation is present. A pulse rate discriminator circuit measures the current pulses and outputs a fire signal if the pulse rate is equal to or greater than the pulse rate produced by ultraviolet radiation from a fire. A background count circuit also measures the current pulses from the ultraviolet light detector tube to test whether the ultraviolet light detector tube is operational. At least one current pulse should be detected within a specified time because the detector tube senses cosmic radiation or radiation from the radioactive source.

Abstract: An integrated electronic control arrangement is disclosed in the illustrative environment of burner such as in a gas-fired furnace. The control incorporates a self-test feature which shuts down the furnace in the event of any one of a number of possible sensed faults. Self-testing occurs automatically before an attempt at ignition and during furnace operation. Proper functioning of the sensor which senses for induced air flow through the burner combustion chamber is tested prior to enabling a fan which causes that induced air flow. Air flow is confirmed by sending to and receiving back from the sensor a sequence of pulses. Should air flow not be sensed during a combustion period, combustion is terminated. A flame sensor is provided for determining the presence of a flame in the combustion chamber. During times when a flame should be present, pulse sequences are sent to and received back from the flame sensor to confirm that a flame is present.

Abstract: A burner control system has a microprocessor for testing parameters of operation and for indicating deviations from a preset range for each. The sensors monitoring the parameters provide their outputs as analog voltages to analog to digital (A/D) converters which provide the parameters in digital form. Tests using preset voltage standards increase the likelihood of A/D converter accuracy. In addition, as operating conditions for the burner change, different preset ranges are used for each sensor output when testing them so as to provide maximum confidence of proper burner operation.

Abstract: An integrated electronic control arrangement is disclosed in the illustrative environment of a gas-fired furnace. The control incororates a self-test feature which shuts down the furnace and displays a diagnostic fault code in the event of any one of a number of possible sensed faults. Self-testing occurs automatically before an attempt at ignition and during furnace operation. The self-test may also be initiated manually at any time the furnace is not operating. The control accepts digital information on daily temperature setback, weekend temperature setback and vacation setback in any one of several preset schedules and preset setback increments. The control has a multipurpose display for selectively showing component indicative failure codes, temperature setback schedules, time of day, and day of the week.

Abstract: A fail-safe electronic position monitoring system for a motor is specifically described in a flame safeguard system. The same fail-safe system could be used more generally in any type of positional monitoring system using a potentiometer. The potentiometer and its wiper are monitored by a microcomputer which has stored in its memory a profile of at least three critical parameters. The parameters are a low voltage parameter, a high voltage parameter, and a parameter that deals with the rate of the voltage level change. The rate voltage level change includes monotonocity function.

Abstract: A fail safe drive circuit for enabling the relay which in turn opens the valve for supplying gas to a burner is disclosed and includes a pair of field effect transistors both of which must be operating properly to enable the relay. One transistor receives an enabling input from a rectifier circuit and will be enabled only if the alternating input signal is of sufficient magnitude and repetition rate. The other transistor is turned on and off by the alternating input signal and the gas valve will be turned on only when each of the transistors is operating in its intended mode. The circuit thus discriminates against false enabling signals such as a direct current signal, line voltage signal, a non-repetitive alternating current signal, or other spurious signal.

Abstract: A microcomputer control utilizes a nonvolatile memory with an interlock. The interlock functions upon the removal of the microcomputer control from a base or from a mounting surface, and its reinstallation. The removal and reinstallation deletes memory and requires reprogramming. This prevents the removal of a microcomputer control that is protected by battery backup without reprogramming the memory. This safety function is particularly useful in flame safeguard or burner control equipment where the interchange of microcomputer fuel burner controls without reprogramming for the particular burner could create a hazard.

Abstract: A fail safe control circuit for supplying gas to a burner is disclosed and includes a plurality of timers, two of which set upper and lower bounds on a window or acceptable time interval during which a third timer must issue a control signal for that signal to be valid. The timers are operated from at least two different sources of timing signals so that a failure of either source of timing signals as well as a malfunction of any one of the three timers will result in an invalid control signal and the control will lock out to preclude burner operation.

Abstract: A fail safe redundancy circuit for controlling a gas valve relay in a gas fired furnace or similar burner is disclosed. The status of the relay contacts is monitored and if those contacts are in the position for enabling the gas valve prior to an ignition attempt, a gate is enabled to shunt the control side of a circuit breaking device such as a fuse to overload that device causing it to kick out or open and interrupt power to the circuit thus disabling the burner. The burner combustion chamber is purged of any accumulated gas after the circuit breaker has been opened.

Abstract: A flame scanning system for monitoring a combustion process by detecting flame emission characteristics in the ultraviolet light spectrum. A metered relative flame intensity signal, flame-off signal, and flame-on signal are provided. A self-diagnostic feature produces a flame marginal signal indicative of substandard flame operation; a tube marginal signal indicative of imminent UV tube failure is also produced. A scanner shutter mechanism includes a check failure feature for detecting UV tube failure. An electronic assisted sighting indicator is also included to assist during on-sight scanner positioning and to provide optimum scanner placement.

Abstract: An ignition control device that utilizes a very sensitive flame rectification signal responsive circuit is disclosed. A printed wiring board arrangement is utilized with a careful arrangement of the conductive areas on the printed wiring board to substantially eliminate leakage paths that can provide a false indication of the presence of flame when none in fact is present.

Abstract: An analog-type fire detector for detecting, in the form of an analog amount, a change in physical phenomena caused by occurrence of a fire, which intermittently detects a change in the ambient physical phenomena caused by occurrence of a fire, generates an analog signal corresponding to an amount of the change, converts the analog signal into a pulse signal of a duration corresponding to the level of the signal, generates periodically from a reference pulse generating means a reference pulse of a predetermined duration, detects by a discriminating means a difference in pulse durations between the output signal from the pulse duration converting means and the reference pulse, charges or discharges a capacitor corresponding to the difference detected, and hold-outputs for a predetermined period by a hold-outputs means a signal corresponding to a voltage across the capacitor at the time when the charging or discharging is stopped.

Abstract: The present invention relates to a digital control circuit which controls the drive of a load by the use of a clock pulse. More particularly, it relates to an integrated circuit device for combustion control which controls the combustion of a burner in a water heater, an air heater or the like. A combustion control circuit performs an ignition operation for a predetermined time, and stops the supply of fuel in case of misfire. When the reception of the time-keeping clock pulses has stopped within the predetermined time, such predetermined time will become infinite, and in the case of misfire, the fuel supply will continue dangerously.

Abstract: Estimated fuel flow rate is calculated by reading first data of the relationship between the opening degree of a fuel control valve and a fuel flow rate. Then, a compensation coefficient is calculated based on the estimated fuel flow rate, and the actual fuel flow rate is controlled on the basis of the compensation coefficient. Estimated excess air ratio is calculated by reading second data representing the relationship between the opening rate of an air control damper and the air flow rate. Then, the actual fuel flow rate and the air flow rate are controlled depending on the predetermined relationship of values between the estimated excess air ratio and the desired excess air ratio.

Abstract: A laboratory gas burner and control apparatus including a burner assembly made from electrically conductive material and adapted for positioning on a counter. Defined by the burner is an inlet for connection to a gas source and an outlet for feeding gas to a flame. An electrically operated valve controls the flow of gas to the burner outlet and an igniter is energizable by a power supply to ignite gas emanating from the burner outlet. Associated with the igniter is an activation circuit that produces either ignition periods during which the igniter is energized by the supply or non-ignition periods during which the igniter is deenergized. Initiation of each ignition period requires manipulation of a manual activation mechanism. Once ignited, the presence of flame at the burner outlet is detected by a flame sensing mechanism. A valve control circuit maintains the supply valve open only during either ignition periods or periods during which flame is detected by the sensing mechanism.

Abstract: A direct ignition gas burner control system includes an igniter, two serially-arranged gas valves for controlling the flow of gas to the burner, and a microcomputer and related circuitry for controlling energizing of the igniter and valves. The microcomputer and its related circuitry provide for numerous options in system functions and for numerous checks on the integrity of the system components.

Abstract: The invention relates to a control circuit for a semi-conductor power element, comprising a circuit generating a signal synchronous with the variable current supply signal of the semi-conductor power element, and a logic circuit with high input impedance to receive directly, on the one hand, the said synchronous signal and, on the other hand, the low strength detection signal and which is such that the delay circuit is combined to the high input impedance logic circuit to prevent the production of control pulses on the electrode controlling the semi-conductor or power element, if one of the components of the control circuit should become faulty.The invention finds an application in burner control and safety devices.

Abstract: A combustion control circuit including semiconductor integrated circuits used for control of a combustor or burner of a water heater, air heater-blower or the like has a very simple configuration for stable initialization against the transient condition of a source voltage. A logic gate performs a sequence control. An input interface section applies a signal to the logic gate in response to an input signal required for combustion control. An output interface section converts the signal produced from the logic gate into a combustion control signal. An operation start signal from an operation switch or a temperature detector circuit is used in combination with an initialization signal for the combustion control circuit.

Abstract: A flame safeguard sequencer incorporates an interlock checking means that verifies the proper status of the start or preignition interlocks in the burner system and the run interlocks of the burner system. In the event that an interlock opens during a period of time when it should not be open, the system can limit the operation of the sequence to a short time period (typically 30 seconds) to allow the interlock to reestablish a normal running state. If the correct state is reestablished, the system continues normal operation. If the correct state is not reestablished, the system is shut down on safety and a coded fault-hold indicator advises a serviceman of where to find the problem.

Abstract: A purge time hold circuit is provided in a flame safeguard sequencer to in turn provide a safe start check of a burner control system. If a flame is indicated during a prepurge period, the purge time hold means will reset to a zero status and the timer will hold until the signal clears itself. If the flame signal does not clear itself within a preset time, a safety shut down will be commanded.

Abstract: Apparatus is disclosed for verifying the proper operation of a drive circuit (43) which controls the application of power to an electromechanical device, e.g., a manually reset circuit breaker (36). The apparatus includes means (60) for applying a control signal to the drive circuit to cause it to briefly apply power to the electromechanical device, where the interval of time over which power is applied is too brief to cause actuation of the device. Means (64) are also provided for sensing the power applied to the device to verify that the drive circuit has properly responded to the control signal.

Abstract: The present invention relates to a self-checking safety switch control circuit for a power combustion system. The circuit comprises a safety switch, a combustion blower relay, a thermal pilot switch, and a fuel supply system. The safety switch operates to detect flow through the combustion system. The safety switch either operates the pilot switch directly or operates the fuel supply system directly to shut down the system if no flow through the combustion system is detected. The circuit has a self-checking feature because combustion cannot be initiated in a subsequent cycle of the system if the safety switch remains in the proven condition from the previous combustion cycle.

Abstract: A fail-safe supervisory circuit for a microprocessor-controlled fuel burner has a diode pump circuit (C4, C5, D7, D8) triggered by a resettable monostable (R7, T2, R8, C3) responsive to an encoded signal from the microprocessor, to act as a watch-dog timer. A triggered bistable (D1, T1, R2, IC8) provides a RESET signal on power-on or manually. A direct connection from this bistable to the monostable enables the timer circuit until the microprocessor program commences.

Abstract: The present disclosure relates to a load drive control element check circuit for checking whether or not conduction and non-conduction troubles take place in a load controlling switching element at the final output stage of a control device, which is required for safety, such as a combustion control circuit.

Abstract: An intermittent gas pilot system utilizing a flame signal simulating circuit means provides for both dynamic as well as static safe start checking for the system. A simulated flame signal is provided so that the relays contained within the system must be checked dynamically before the system will allow the opening of the main gas valve.

Abstract: A flame detector for monitoring the flame of a burner including an electrically actuatable photo shielding element positioned between a photoelectric element and the flame. The normally transparent photo shielding element may be turned opaque on command for simulating a no flame condition of the burner. The resulting signal from the photoelectric element is compared with a predetermined signal level, when there is actually no flame, for testing the flame detector.

Abstract: The invention relates to the control of burners, e.g., for boilers or furnaces and has for its objective to provide means whereby the combustion conditions existing at a burner are initially governed by pre-determined conditions which conditions can be automatically maintained or improved during the operation of the burner.

Abstract: A dual solenoid burner control system particularly adapted for a gas clothes dryer. A controlled switching element, such as a triac, is advantageously employed in a circuit arrangement which accomplishes the various operational functions required of such circuits, and which permits the use of single-winding solenoid gas valves and a simple single-pole sensing switch for sensing igniter ignition condition or flame heat. The preferred embodiments interrupt gas flow in the event of triac failure, whether open-circuited or short-circuited. In an additional system function, the change in winding impedance as a solenoid valve operates normally is sensed and advantageously utilized to cause the first valve to close in the event the second valve does not properly operate.

Abstract: A flame detection and proof device utilizing NAND logic implemented by MNOS devices which provides safe control of gas systems and appliances. Improved control is achieved by using a flame probe for providing signals indicative of flame and no-flame conditions connected to circuit means which includes at least one delay circuit for producing a first output signal during a set time period for ignition and also during indication of a flame condition and a second output signal after the set time period and during an indication of no-flame condition. A relay is responsive to the output of the circuit means to be activated during the first output signal and to be deactivated during the second output signal.

Abstract: A control logic means or microcomputer controlled burner control system has been disclosed. The system utilizes a safety relay that has contacts that are in series with all of the other loads for the system. The safety relay contacts are checked prior to operation of the system to verify their ability to open the load circuit. The operation of the electronics for the control of the safety relay are regularly checked during the operation of the system by a combination of feedback circuits from the electronics, and from the final control element for the various loads.

Abstract: A primary oil burner safety control and intermittent ignition system for initiating and supervising the combustion of fuel oil in furnaces, the system including thermostatic switch means controlling the energization of a relay having contacts controlling the energization of an oil burner, means constantly monitoring the state of the relay contacts with respect to the state of the thermostatic switch means, and means to effect safety shutdown of the oil burner in the event the state of the relay contacts disagrees with the state of the thermostatic switch means.

Abstract: A control arrangement for a fuel ignition system having pilot and main valves in which the energization of the operate windings of the pilot and main valves, which are connected in series, is controlled by a silicon controlled rectifier. The SCR is enabled at the start of each ignition cycle by trigger pulses provided by a pulse generating circuit and when enabled, the SCR provides a shunt circuit path around the main valve winding permitting the pilot valve winding to be energized at its operating level effecting pilot valve operation and preventing the main valve from operating. When a pilot flame is provided, a capacitor of a flame sensing network is charged by flame rectified current, generating an inhibit signal for the pulse generating circuit which causes the SCR to be cut off, interrupting the shunt path to allow the main valve winding to be energized, effecting main valve operation.

Abstract: A check circuit for checking operation of timers of a digital type combustion process control apparatus comprises flip-flops each having a preset terminal. The preset state of the flip-flops is inverted by an operation starting signal. The inversion is detected by a detector circuit the output signal of which is utilized for driving the control circuits for a combustion apparatus. The detector circuit is composed of a flip-flop circuit having input terminals applied with the operation initiating signal and the inverted output signal from the timer circuit.

Abstract: A safe start check circuit for a fuel burner is disclosed. Two relays are arranged to insure proper start and to protect against component failure. Delays in operating the relays, and a normally closed control relay contact serve to both prevent relay races and provide protection against a solid state switch means failure.

Abstract: A gas monitor system to monitor combustable or flammable gases present in the exhaust flue of the monitored equipment and to adjust the damper on a real time basis as the system is operated to continuously adjust the concentration of combustible or flammable gases in the monitored equipment. The system also includes self-check calibration circuitry to regularly check that the system is in calibration and that the sensor element in the exhaust has not suffered from a sensitivity decrease. Calibration gas is fed to the sensor on a regular basis. If the calibration circuitry does not complete a proper timing cycle, the system is disabled indicating that the instrument is out of calibration or the sensor is defective.