Primary gas furnace control

Patent · Tue Jul 14 04:00:00 EDT 1987

OSTI ID:6287285

Geary, F J

A primary control is described for gas furnaces, the combination including a low voltage circuit adapted to be connected to a source of low voltage AC current, the low voltage circuit including a thermostatic switch, an electrically operable pilot gas valve, an electrically operable main gas valve, pulse generating means for controlling energization of the main gas valve including a programmable unijunction transistor, and first relay means controlling the energization of the main gas valve and the pulse generating means. A high voltage spark generates circuit including a silicon controlled rectifier and spaced electrodes disposed in the path of gas emanating from the pilot valve. The programmable unijunction transistor controls the conduction; means interfaces the low voltage circuit and the spark generating circuit and providing a substantially higher voltage in the spark generating circuit than in the low voltage circuit. A flame sensing means includes a probe disposed in the path of gas emanating form the pilot valve and subjected to the heat of the gas flame when gas ignition is obtained by the spark generating circuit where flame rectification is effected by the probe. The flame sensing means controls the energization of the main gas valve and the pulse generating means through the first relay means.

• Assignee: Robertshaw Controls Co., Richmond, VA
• Patent Number(s): US 4680005
• OSTI ID: 6287285
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
421000* -- Engineering-- Combustion Systems
ALTERNATING CURRENT
CONTROL EQUIPMENT
CONTROL SYSTEMS
CURRENTS
ELECTRIC CURRENTS
ELECTRIC DISCHARGES
ELECTRIC POTENTIAL
ELECTRIC SPARKS
ELECTRICAL EQUIPMENT
ELECTRONIC CIRCUITS
ELECTRONIC EQUIPMENT
EQUIPMENT
FLAME PROPAGATION
FUNCTION GENERATORS
FURNACES
GAS FURNACES
PULSE GENERATORS
RECTIFIERS
RELAYS
SEMICONDUCTOR DEVICES
SEMICONDUCTOR RECTIFIERS
SWITCHES
THERMOSTATS
TRANSISTORS