Carrier Corporation

Hamilton Standard Controls, Inc.

Larry E Wilson

Craig R Knotts

Daniel L Kelly

Gary D Wedlake

Dennis L Harris

A control for a water heater having upper and lower heating elements assures that the upper heating element is not activated until certain control conditions are met. The control first determines whether the temperature sensed by a sensor in the vicinity of the upper heating element has reached a predefined set point temperature for that sensor. The control thereafter determines whether the temperature sensed by the sensor declines at a rate greater or equal to a threshold rate of temperature change before authorizing any activation of the upper heating element.

Control for electric water heater

A flame sensor for sensing flame produced by the burner of a furnace. The sensor includes a closed end tube having a photosensitive element located therein. The photosensitive element is sealed off from any external light so as to only respond to infrared wavelengths of light emitted from the end of the tube when subjected to a flame produced by the burner of the furnace.

Optical flame sensor having opaque hollow tube

An ice making machine detects when to harvest the ice being formed on an ice forming plate. A circuit analyzes the response of a capacitor formed by the ice forming plate and a conducting plate positioned opposite the ice forming plate wherein the dielectric medium therebetween substantially consists at some point in time of the ice formed on the ice forming plate.

Ice detection in ice making apparatus

A system for detecting the formation of ice on a cold surface includes an electrical circuit for sensing the electrical responsiveness of a capacitor formed by a conductive plate positioned opposite the cold surface. The ice formed on the cold surface will eventually comprise most of the dielectric medium between the conductive plate and the cold surface thereby providing a distinctively recognizable electrical response that is sensed by the electrical circuit.

Ice detection system

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.

Flame sensor verification

A flame sensor senses the intensity of a pilot flame to determine whether main burner ignition has occurred in a gas furnace. The sensor includes a computer which is operative to trigger the sensing of the flame intensity following the provision of gas to the main burner. Circuitry associated with the computer preferably provides an indication of the pilot flame intensity to the computer through a measurement of the electrical conductivity of the pilot flame following provision of gas to the main burner.

Flame detection system

A fail-safe gas valve driver circuit controlling the gas supply line of a gas burner, which circuit in its essential circuit elements (FIG. 1) includes an appropriate switching means (S1) effectively feeding a pulsed DC wave form into the rest of the valve relay driver circuit, operatively consisting only of a capacitor (C1) in series with a gas valve relay (K1), which in turn is in parallel with a diode (D1). In operation, the valve relay coil is energized by charging the capacitor with the switch connected to a positive DC voltage source (V.sub.dc ; FIG. 1A), and then grounding the positive end of the capacitor (switch connected to ground) applying a negative voltage across the coil of the relay (FIG. 1B). When the capacitor is again connected to the positive DC voltage source by the switch, the current in the relay coil is sustained by the diode (FIG. 1C). The switch is operated at a sufficiently high rate so the current in the relay coil has insufficient time to decay significantly during the charging cycle of the capacitor before being replenished during the capacitor discharge cycle. With this circuitry the gas supply valve (G.V.) will always go to, or be maintained in, a closed position, regardless of what component(s) of the valve relay driver circuit might fail or deteriorate. Any inadvertent supply of gas to the burner due to any component failure is avoided without any component redundancy. Two exemplary, transistor switching circuits are described (FIGS. 2 & 3).

Fail-safe valve relay driver circuit for gas burners

A compact and inexpensive current sensor includes a planar coil assembly mounted, as by printing, on a substrate such as a circuit board. A closed-loop flux concentrator extends through the coil and also through the board. A conductor carrying the AC current to be sensed is positioned in proximity with the flux concentrator. The flux concentrator is of one-piece construction, having a pair of opposed leg portions in overlapping relation and fastened to the circuit board. A current-summing amplifier amplifies the low-amplitude emf provided by the coil assembly and, with further circuitry, provides an indication and/or control commensurate with the sensed current being above or below some value.

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Marion, IN, United States of America

Larry E Wilson