Automatic fuel ignition system with redundant flame sensing
AssigneeRobertshaw Controls Company
InventorsAllen L. Teichert, William W. Chambers
Life of this patent
Estimating the term…
Abstract
An automatic fuel ignition system has a spark generator for igniting a pilot burner and two separate pilot flame sensing systems to provide a redundant safety check of flame ignition before the main burner gas is turned on. One sensing system includes a rectifying electrode in the pilot burner flame and a electronic flame sensing circuit responsive to the flame conductivity while the second sensing system includes a flame switch located in the flame and responsive to the heat of the flame.
Claims20
In an automatic fuel ignition system for a heating system having a main burner system a pilot burner, the combination comprising
- a pilot valve for supplying gas to the pilot burner,
- a main gas valve for supplying gas to the main burner,
- condition responsive means for actuating the pilot valve,
- spark generator means for igniting the pilot burner,
- a sensing electrode in the pilot burner flame,
- an electronic flame sensing circuit in circuit with said electrode and responsive to the increased conductivity of the pilot flame for sensing the presence of the pilot flame,
- switching means responsive to the flame sensing circuit to actuate the main gas valve in response thereto, and
- flame responsive switch means for sensing the heat of the pilot flame and connected in circuit with the switching means and the main gas valve so that the main gas valve can be actuated only when the pilot flame is sensed by both the flame sensing circuit and the flame responsive switch means.
An automatic fuel ignition system for a heating system having a main burner and a pilot burner comprising
- condition responsive switch means for energizing the system,
- a pilot valve actuated by the condition responsive switch means to supply gas to the pilot burner,
- spark generating means for igniting the pilot burner,
- flame sensing means which comprises an electronic flame sensing circuit for sensing the presence of the pilot burner flame and switching means responsive thereto for switching from a first to a second state,
- a flame switch responsive to the heat of said pilot burner flame,
- a main gas valve in circuit with said switching means and said flame switch and actuated by the switching of the switching means and flame switch to supply gas to the main burner, and
- lock-out switch means including actuator means and contact means, the actuator means being in the first state for a predetermined time to operate the contact means for deenergizing the system and being moved from said first state responsive to both of said switching means and said flame switch.
An automatic fuel ignition system for a heating system having a main burner and a pilot burner comprising
- a pilot valve supplying gas to the pilot burner
- a main gas valve supplying gas to the main burner condition responsive means for actuating the pilot valve,
- automatic ignition means to ignite the pilot burner,
- conductivity responsive flame sensing means for sensing the pilot burner flame by responding to the flame conductivity, and
- thermally responsive flame sensing means for sensing the pilot burner flame by responding to the flame heat,
- the main gas valve being actuated only when both of the conductivity responsive flame sensing means and the thermally responsive flame sensing means sense the pilot burner flame.
Dependencies are inferred from the claim text.