US3030023A - Gas burner electrical control - Google Patents

Description

April 17, 1962 B. MATTHEWS 3,030,023

GAS BURNER ELECTRICAL CONTROL Filed Feb. 9, 1959 INVENTOR. BIRCH/m0 MA TTHEWS BY. @u M, 62 52% 1* @mx,

ATTORNE'VS- United States PatentOfifice dfidfififi Patented Apr. 17, 1962 3,030,023 GAS BURNER ELECTRICAL CONTROL Birchard L. Matthews, Cleveland, Ghio, assignor, by mesne assignments, to Aurora Corporation of Illinois, a corporation of Illinois Filed Feb. 9, 1959, Ser. No. 7%,216 2 Claims. (Cl. 236-1) This invention relates to gas burner controls, and more particularly to an improved output temperature manual setting and automatic regulating device therefor.

An object of the present invention is to provide an improved automatic output temperature regulating system for gas burner heads, such as is manually adjustable to procure any desired output temperature at the cooking vessel.

Another object is to provide an improved output temperature control mechanism as aforesaid, employing at each burner head a plurality of burners separately controlled to either fully off or fully on conditions, thereby avoiding low flame and incomplete combustion operating conditions incidental to automatic maintenance of the output temperature as prescribed by the manual setting of the device.

Another object is to provide an improved automatic control mechanism as aforesaid which is simple and inexpensive to manufacture, and which provides sensitive and accurate automatic regulation of the output temperature, while being rugged and positive in action.

Other objects and advantages of the invention will appear from the specification hereinafter wherein:

PEG. 1 is a schematic illustration of a multiple burner head output temperature control and regulating mechanism ofthe invention; showing the mechanism in total gas off condition;

' FIG. 2 is a view corresponding to a portion of FIG. 1,

showing the control and regulating components of the mechanism when the manual control is set to the desired output temperature, and when the regulating component of the mechanism is calling for full gas flow to all burners;

FIG. 3 corresponds 'to FIG. 2 but illustrates the condition of the regulating component as the output temperature approaches the dialed temperature, whereby the gas supply to one burner is cut off;

FIG. 4 corresponds to FIGS. 2, 3, but shows the regulating mechanism in the condition thereof when the dialed output temperature is reached or exceeded, whereby the gas supplies to both burners are cut off; and

FIG. 5 illustrates schematically a dual gas burner head and gas supply regulating arrangement of the present invention.

As shown in FIG. 5 the burner control and temperature regulating device of the present invention may be employed for example in connection with a gas burner head designated generally at and comprising a low input burner 12, a main burner 14, and a pilot light 16. The gas supplies are shown to be in the form of conduits lltt, 19, 20; and it will be understood that the pilot jet to may be adjusted to burn constantly with or without boosting, as preferred. The burner supply conduits 18, 19 are arranged to be controlled by off-on solenoid actuated valves 22, 24, respectively; whereby it will be appreciated that openings of the solenoid valves will cause their corresponding burners to be ignited from the pilot.

As shown in FIGS. 1-4, the burner control and automatic temperature regulating mechanism which actuates the valves 22, 24 is controlled manually by rotation of a knob or the like which for example may be disposed at the front of a gas range (not shown) which turns a control shaft 25. The shaft 25 carries a cam 26 which bears against a lift portion 28 of a bracket 39 which is pivoted as indicated at 32 to the range structure. The bracket 30 mounts in parallel cantilever extending relation electrically conductive spring arms 34-, 36, 33 carrying contact points 4t 42, 44 respectively.

Contact 44 electrically connects through arm 34 to a conductor 46 connecting in series the coil of the valve solenoid 24 and leading thence to a house current supply as indicated at 50 (FIG. 1). The contact 44 electrically connects through arm 38 and coil of valve solenoid 22 to the same power supply terminal. Contact 4 2 electrically connects through arm 36 to a conductor 52 leading to the other terminal of the power supply 59. Thus it will be appreciated that whenever contacts 42, 44 are made, the valve 22 will be opened to supply the burner t4; and that whenever the contacts 49, 42 are made, the valve 24 will be opened to supply gas to the low input burner 12.

To impose automatic regulation of the output temperature upon the manual control facility hereinabove described, a variable position buttress is provided in conjunction with the contact carrying spring arms 34, 36, 38.

For example, as shown herein the buttress may comprise an abutment member 54 carried at one end of a bimetallic bar 55 which extends in cantilever relation from a stationary fixture 56. A heating element, such as a coil of resistance wire 58 in series with a conductor 59 and a temperature-sensitive resistor 60 (which may be either of the type known as a thermistor or a varistor, hereinafter sometimes referred to as a heat sensing element) and a house current supply 62, is provided to automatically control the bi-metallic bar 55.

The heat sensor 60 may be of any suitable variable resistance type but as shown in the drawing herewith a thermistor type sensing element is used, and is preferably mounted at the center of the burner head as shown in FIG. 5 so as to contact the bottom center portion of the cooking vessel. Thus, for example, temperature increases at the cooking vessel will cause immediate change in the resistance characteristics so as to allow more current to flow through the bi-metallic heating coil 58, causing the latter to bow away from the contact members; and vice versa.

It will be appreciated that commencing with the control situation illustrated for example by FIG. 1, wherein the manual control shaft is set at off position (as will of course be indicated on the accompanying dial, not shown) all contacts are open; both gas supply valves are closed; the thermistor 6b is cold; and the bi-metallic heater 58 is deenergized. Then upon manual turning of the burner control and setting of the dial to the desired temperature, the shaft 25 will set the cam 26, for example to the position shown in FIGS. 24. Initially, as shown in FIG. 2, this setting of the cam 26 will lift the bracket 3% so as to cause all of the spring arms 34, 36, 38 to move upwardly and bear at their contact points in succession against the abutment member 54. This energizes both solenoids whereby both valves are opened wide to supply gas to both burners, which are thereupon ignited by the pilot 16. As the cooking vessel heats up the thermistor 6th senses the output temperature gradient and gradually admits an increasing current flow to the bimetallic heater. This causes a corresponding bowing away of the abutment member 54 from the contact ends of the arms 34, 36, 38.

The parts of the mechanism are so arranged that prior to actual attainment by the cooking vessel of the prescribed temperaturethe apparatus anticipates the event and the bimetal bar 55 bows sufficiently to open the contacts 40, 42, as shown in FIG. 3. This deenergizes the solenoid 24 thus closing the valve supplying gas to the burner 14; and the temperature gradient at the cooking vessel then coasts into the prescribed level, thereby minimizing the chance of over-shooting the desired ternperature. Thenceforth temperature variations at the cooking vessel are sensed by the thermistor and cause the heater coil 58 to provide sensitive temperature regulating control of the position of the abutment member 54.

For example, if the vessel tends to overheat, the abutment member will move still further away as illustrated for example by FIG. 4, whereupon both solenoid valves are deenergized and closed, thereby depriving the burner of gas supply according to the heat consumption requirements at the moment. Thus, opening and closing cycles involving one or both sets of solenoid control contacts will continue automatically to provide a uniformly regulated temperature condition at the cooking vessel at whatever temperature may have been prescribed by the manual setting of the control shaft 25. It is a particular fea ture of the temperature maintenance arrangement of the present invention that it functions entirely automatically through use of separately supplied burners operating at all times under either fully on or fully oil conditions. Thus, no dangerous flash back or low flame burner operations are involved, such as would result in undesirable incomplete combustion situations.

It will of course be appreciated that although the drawing and description herein refers by way of example to a gas range burner arrangement, the invention is equally adaptable to use with any gas appliance having any preferred number of any type burners in a burner head unit; and that other changes may also be made in the mechanism described by way of example herein without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. In combination with a gas range burner head including a pair of gas burners each having an independent gas supply conduit, a valve in each supply conduit operable alternatively between full open and full closed positions, a control element mounted in close proximity to said burner head to sense the temperature of material heated thereby, said control element having an electrical resistance variable inversely of its temperature, a bimetallic bar mounted in cantilever fashion, an electrical heating element adjacent said bar, a source of electric current, said control element and said heating element being connected in series across said source so that deflection of said bar will be directly proportional to the temperature of said control element, an abutment member fixed to the free end of said bar, a switch assembly movably mounted adjacent said bar and including three electrically conductive spring arms fixed in spaced relation to each other and mounted in cantilever fashion at one end and carrying normally spaced contact points at their free ends, manually operable means for moving said switch assembly to move said free ends of the spring arms toward and away from said abutment member between two positional extremes, one in which all of the contacts are engage and said spring arms are deflected while the bar is undeflected, and the other in which all of said contacts are spaced apart while the bar is undeflected, solenoid means for actuating each of said valves, the center spring arm being connected to said current source and the two outside arms being connected in parallel, through the respective solenoid means, to said current source.

2. In combination with a gas range burner head including a pair of gas burners each having an independent gas supply conduit, a valve in each suppply conduit operable alternatively between full open and full closed positions, a control element mounted in close proximity to said burner head to sense the temperature of material heated thereby, a switch assembly including three electrically conductive spring arms fixed in spaced relation to each other and mounted in cantilever fashion at one end thereof and carrying normally spaced contact points at their free ends, an abutment member, means mounting said abutment member adjacent said free ends of the spring arms and connected to said control element for actuation thereby to move said abutment member toward and away from said spring arms in response to temperature variations sensed by said control element, manually operable means for moving said switch assembly to move said free ends of the spring arms toward and away from said abutment member between two positional extremes, one in which all of the contacts are engaged and said spring arms are deflected by engagement with said abutment member while the abutment member is most closely positioned relative to said spring arms, and the other in which all of said contacts are spaced apart while the abutment means is most closely positioned relative to said spring arms, a source of electric current, solenoid means for actuating each of said valves, the center spring arm being connected to said current source and the two outside arms being connected in parallel, through the respective solenoid means, to said current source.

References Cited in the file of this patent UNITED STATES PATENTS 1,811,378 Bannister June 23, 1931 2,083,932 Von Ohlsen June 15, 1937 2,275,042 Cobb Mar. 3, 1942 2,331,570 Ray Oct. 12, 1943 2,581,942 Collins et al. Ian. 8, 1952 2,615,085 Smulski Oct. 21, 1952 2,700,505 Jackson Ian. 22, 1955 2,819,372 Booker et a1 Jan. 7, 1958 2,846,556 Whinery Aug. 5, 1958 2,882,379 Long Apr. 14, 1959

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