Hamilton Standard Controls, Inc.

Stephen E Youtz

Eugene P Mierzwinski

Michael T Grunden

Victor F Scheele

Edward C Rose

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. When it is known that no flame is present, if sent pulses are received back, a fault has occurred and the system locks out. If, at any time, any pulses are received when none were sent the system also locks out.

Integrated furnace control having ignition switch diagnostics

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.

Integrated furnace control and control self test

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.

Fail safe gas valve drive circuit

Integrated furnace control having ignition and pressure switch

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.

Control system with timer redundancy

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.

Gas valve relay redundant safety

A sealed enclosure is provided for electrical circuitry to be located in a moist environment, as near a spa. The enclosure includes a housing of electrical insulating material, a display overlay adhesively bonded to the housing and covering certain openings in the housing for switches and displays, and a retaining bezel over the graphic overlay. Relief porting is provided in the bezel, and preferably also through a flange in a contiguous portion of the housing for assuring that water deposited on the display overlay will be drained away and thus not degrade the seal between the overlay and the housing.

Growing community of inventors

Fort Wayne, IN, United States of America

Stephen E Youtz