US2067481A - Power circuit for electric ranges - Google Patents

Description

Jan. 12, 1937. D F|NDLAY 2,067,481

POWER CIRCUIT FOR ELECTRIC RANGES Filed Nov. 19, 1934 BROIL PREHEAT I POSITION "PREHEAT' "BAKE" 5 POSITION v INVENTOR= a 2 D UGLAS 0. FIN AV x I I I F1 g3 trolled circuit breake Patented Jan. 12, 1937 POWER CIRCUIT FOR ELECTRIC RANGES Douglas David Findlay, Carleton Place, Ontario, Canada Application November 19, 1934,

Serial No. 15355955 for electric ranges and more particularly to the electric circuits for controlling the flow of current 'to the heating elements. 5' In ovens of this character it is common practice to .provide two heating elements, a top element and a bottom element, sometimes with a switch controlling the power supply to both elements and a single-pole thermostatically conin the baking element circuit, but more ge erally with two switches, one for each heating element and a double-pole thermostatically controlled circuit breaker which interrupts the power supply to each switch. The latter arrangement 'is cumbersome and expensive while the former is only partially automatic.

Sometimes, in order to control both oven elements with a single pole circuit breaker, both elements are red from the same controlled leg of the 3-wire supply in parallel. This arrangement causes an undesirable voltage drop, resulting in slower action in the preheating position, and creates an unbalanced load, which is objectionable. A pilot light is sometimes provided to indicate when the elements are energized. Such circuit arrangements have not provided for most efllcient and rapid preheating of the oven, nor do they provide for single manual control of the power load circuit whereby both heating elements may be connected in series with high voltage current supply or either element separately with low.,voltage current supply.

An object of the present invention is to provide an improved circuit including a single-pole thermostatic circuit breaker and pilot light with uni-'- tary manualcontrol, so that both heating elements may be heated in series at high voltage and either of the elements may be heated separately at low voltage. A further object is to provide a circuit arrangement in which a relatively inexpensive single-pole thermostatic circuit breaker and pilot light are incorporated in all oi. a plurality of the oven heating circuits con-, trolled by a manually operated switch, andin which the lower voltage power supply is provided for each heating element through the leg of the power supply circuit which contains the thermostatic circuit breaker. Another object is to pro vide an improved dial arrangement for setting the temperature at which the thermostatic circuit breaker automatically breaks the power supplycircuit feeding the heating elements. Y

The invention will now be described with reference to the accompanying drawing, in which Figure 1 represents the electric circuit;

vstrated in Figure 3.

. 3 Claims. 01. 219-40) This invention relates to oven heat control Figure 2 is a front view of an'electric range, partially broken away;

Figure 3 represents the three difierent connections of the heating elements in the circuit; and

' Figure 4 illustrates an arrangement of. the dial 5 'oi the thermostatic control on the panel.

' In the drawing, I represents the top and 2 the. bottom heating element for the oven illustrated in Figure 2. 3 is a multi-way switch, operable from the switch panel 4; 5 a single-pole .thermo- 10 statically controlled circuit breaker, of well known construction, having a control dial 6 on the switch panel, and 1 represents fused cutouts for the power supply which is connected to the terminal block 8 for reception of 220 volt current 5 or volt current, depending upon the position v of the switch 3. A pilot light 9 is connected with the circuit breaker 5 and the common line terminal l3. c

The heating elements I and 2 are connected in series and to the switch 3 with wires l0 and. II, while a common wire l2 also contacts with the switch at a point IS. The power line H connects one fused cutout with the switch, while the other power line l5 passes through the circuit breaker 5 to the switch and the neutral line It leads directly from the terminal block to the switch.

The dial for setting the temperature at which the thermostatic circuit breaker operates to interrupt the current flow is arranged in an opening in the panel 6', as illustrated more or. less diagrammatically in Figures 2 and 4. The dial may take the form of an open ended cylinder I! mounted for rotation on ashait l8 and having a transparent well ill carrying a desired temperature scale. An index pointer 20 is provided on the outturned lip of the panel opening. The dial may be provided with knurls 2| to afford gripping contact for rotating the dial. The pilot to light 9 is locatedwithin the cylinder to illuminate the temperature scale and, at the same time, indicate if the power is on or oil. Alternatively, if desired, the pilot lamp may be arranged behind a window in the panel in a known manner. The three operating positions of the circuit with respect to the two heating elements, as controlled by the switch, are diagrammatically illu- In the preheating or 1 position, when it is'desired to raise the tempera- 50 ture of the oven quickly, both elements are energized in series by the 220 volt current supply of the two power lines It and I5, the neutral wire being broken as indicated. at X. With the switch in the 2 position Bake or 3 position 55 Q "Broil", the same power circuit energizes the heating element l or 2 as required with 110 volt current sup ly of one power line l5 and utilization of the neutral wire I6, the other power line ll being broken as indicated at X in each case. The thermostat control and pilot light are, as shown, in the energized circuit in all positions. The operating positions of the circuit may be -described with respect to Figure 1 as follows: (1) line I! through switch to wire I, element I, element 2, wire ll through switch to line ll; (2) line l6 through switch to wire H, element 2, wire I! through switch to neutral line It; (3)

line I5 through switch to wire Iii, element 1, wire l2 through switch to neutral line It. The utilization of power line IS in all operating positions permits control of the circuit at all times by means of the single-pole circuit breaker 5 in the line IS. The pilot light 9 by connection to the circuit breaker and to wire i2 at terminal l3 of the switch is also in the energized circuit at all times.

It will be observed that this circuit arrangement aflords simplicity of operation by a single manual switch control of all heating positions oi the elements, while in all such positions the circuit is automatically controlled by the singlepole thermostatic circuit breaker, with the pilot light burning when the power is on. With the switch in No. 1 position, the two heating elements are connected in series across the high voltage line, giving maximum heating eflect in the oven, while in positions No. 2 and No. 3 of theswitch the baking and broiling circuits, respectively, are energized. The pilot light is always in circuit with the automatic control and thus when the automatic control breaks the circuit the light goes out, indicating that the desired oven temperature has been reached. This automatically indicates the time at which the switch 3 should be manually shifted. It will be appreciated that this arrangement greatly facilitates minimum power consumption as well as maintenance oi best temperature conditions in the oven.

with this circuit arrangement a single-pole, relatively inexpensive circuit breaker adequately provides for thermostatically breaking whichever power circuit may be in operation. The switch 3 may be 01 any desired construction to operate as shown.

I! desired, the pilot light may be arranged to come on when the temperature, for which the thermostatic circuit breaker is set, has been reached. In this case the pilot light is connected across the binding posts of the circuit breaker 5.

A clock maybe inserted in the power load circuit between the circuit breaker and the terminal block to close and break the circuit automatically at fixed times.

The circuit is adapted for any desired power voltages and the higher voltage may. be double the lower voltage or the square root of three times the lower voltage, as is sometimes the case.

I claim:

1. An electric circuit for the oven of cooking ranges comprising two heating elements, a power supply circuit for said elements including two energized wires and a neutral wire, and control means for said circuit comprising a switch, said energized wires and the neutral wire being connected to terminals in the switch, connecting wires leading from terminals in the switch to each of said elements and a third common wire leading from a terminal in the switch and connected to both of said elements, the switch in one operating position being arranged to connect the terminals of said energized wires to the terminals of said connecting wires with the terminals of the neutral wire and the common wire disconnected, and in other operating positions to connect the terminal of the same one oi the energized wires to either of the terminals of the connecting wires and the terminalof the neutral wire with the terminal 01' said common wire, whereby one of said energized wires is commonly utilized in all operating positions. oi said circuit.

2. A circuit as defined in claim 1 wherein a single-pole thermostatically controlled circuit breaker is interposed in said commonly utilized wire and arranged to open and close said circuit when the temperature in the oven reaches predetermined limits.

3. A circuit as defined in claim 1 wherein a single-pole thermostatically controlled circuit breaker is interposed in said commonly utilized wire and arranged to open and close said circuit when the temperature in the oven reaches predetermined limits, and wherein a pilot light is connected between the circuit breaker and said common wire terminal of said switch whereby

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