US2151782A

US2151782A - Pilot light for ovens

Info

Publication number: US2151782A
Application number: US66017A
Authority: US
Inventors: Edwin H Lockwood
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1936-02-27
Filing date: 1936-02-27
Publication date: 1939-03-28
Anticipated expiration: 1956-03-28

Description

Patented Mar. 28,1939 I "mrao PHD! LIGHT FOR @VENQ Edwin H. Lockwood, Mansfield, om, assignor m Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa, a corporation or Application Ferm -yer, ices, (or. 177-811) It is a further object of this invention'to indicate the condition ,or a thermostat controlling the oven so that the operator shall not be required to listen for the cllcls oi the thermostat when it is changing connections.

It is a further object of this invention to provide such an indicator which will operate in all on positions of the operating switch.

Other objects or the invention and details of the proposed construction will be apparent irom the iollowingdescrlption and the accompanying drawing, in which the single figure is a. circuit diagram illustrating the apparatus and connections used in this invention.

In the dia, power mains I and 2 and neutral wire 3 of the three-wire system are shown.

A switch is provided which I have illustrated by means of a diagram including a cam t. This illustration is not restrictive. Any switch which will make the described connections may be used. No invention in the switch per 'se is the subject of this application.

A connection 3 from the main wire i to the blade s of the switch is continued, when the cam d has been rotated to close the switch 8, through the wire l to one terminal e of the thermostat. This occurs when the com d has been rotated clockwise until the mark comes into the position opposite the reference mark indicated as an arrow. The mark 03" is shown as opposite said reference mark in the drawing.

A connection it from the wire 2 to the switch blade 9 is continued, when the switch is closed, over wire ii to the heater it in the bottom oi the oven, and from the heater 6% a wire It extends to a terminal it of the thermostat. The heater it is located near the bottom of the oven, which'is diagrammatically indicated by the rectangle 85.

Another blade operated by a separate proiection on the cam is shown at It. and controls aconnection from the wire ill to the wire it which goes to the top heater ll of the oven and tromthere a wire It extends to a terminal it of the thermostat. Between the terminal i9 and the terminal 8, the thermostat has a conducting block which is connected by wire '28 to a lamp 2! and thence through a wire it to the neutral wire 8.

i No. 86.01!

The thermostat as illustrated is of the familiar snap-action disc type, but any suitable form of thermostat may be used. The disc 28 is illustrated in its composition. when heated, this disc moves with a snap action to a position 5 in which all the circuits controlled thereby are opened. The mechanical details or the way this is done are illustrative only and are intended merely to indicate the control of the circuits by the thermostat. I is The terminal it, when the thermostat is in circuit-closing position, is connected by the bridging-piece 26 to a block dl. Similarly, the bridgins-piece it connects the terminal it with the block it, when the disc is in the illustrated posi- 1s tion, and at the same time the bridging piece 29 connects the block it to the terminal 8. A resistor 30, which acts as a radiant heating coil to narrow the temperature difierential of the thermostat, is connected between the block 2? and 20 the terminal i9.

In the operation of the device, when the cam d is rotated clockwise from the illustrated position to the position in which BA is uppermost. (opposite the reference arrow) the switches 6 5 and 9 are closed and switch it is open. A circult is then established from the main wire i over the wire 5, switch blade 5, wire l, terminal 8,. bridging-piece 29, block 26, wire 2i, lamp 22 and wire 23 to the neutral wire 3.

A circuit is also established over the wire iii. switch blade 9, wine ii, bottom heater i2. wire it, terminal is, bridging-piece it, block 2i, resistor 3t, te it, bridging-piece it to block 2d, brldging piece 2t, terminal 8, wire I, switch as t and wire 5 to the main wirei.

It will thus be seen that with the cam. t in the position described, the bottom heater i2 is connected between the main wire 2 and the main wire 8. It is also connected through the so lamp 22 to the neutral 8. The top heater ii is disconnected. the switch blade is being in opencircuit position. This position of the cam switch 6 is the position used for baking. It gives a medium heat.

When the cam 5 is being movedto the BA position it passes through the position in which the mark PH is opposite the reference mark. Ii it be stopped in this PH position, the switches 9,

t and it are all closed. The circuit is through a as and from there to block as. From cs the block 20 both of these circuits are completed over bridging-piece 28 and switch 6 to the other main wire I. The lamp 22 is also energized by reason of the diflerence in potential between block 20 and neutral wire 3.

The position of the cam is for preheating. It isthe position used when the oven is first energized, and its purpose is to bring the oven quickly to the desired temperature. Afterthe oven has reached the desired temperature, the cam is turned to one of the other positions.

It the switch be turned until the mark BR is at the index point, the switches 6 and i5 are closed and the switch 8 is open. There is then established a circuit from main wire 2 over wire i0, switch l5, wire I6, top heater I'I, wire i8, terminal l9 and bridgin -piece 28, the block 20, bridging piece 29, terminal 8, wire I, switch 6 and wire 5 to main wire I. There is again a connection from block 20 through the lamp 22 to the neutral wire 3. y

This is the broiling position in which a medium heat diil'ering in degree from the before-mentioned medium heat is obtained. The difference in degree of these two medium-heat positions is eflective even when the energy for which the two heaters l2 and I! are designed to be equal, because one of these two is farther from the object to be heated than the-other. The broiling is obtained by placing the article to be heated near the top of the oven, and, the top heater being close thereto, the cooking is by radiant heat. In the baking position. of the switch, the cooking is principally done with heated air heated and circulated by the bottom heater.

It will be observed that the lamp 22 is in the connection from block 20 to the neutral wire and that this connection does not include any of the cam-operated switches. Moreover, the connection from main wire I to block 20 does not include any of the heaters. When any of the heaters are working, therefore, block In is at a different potential from neutral wire 3 and the lamp 22 will shine. The connections herein tracedfrom main 2 through one or both heaters to the block 20 are, when the thermostat is closed, equivalent to a connection, not to the neutral wire 3, but to the main I because of the difllerence of potential just mentioned. Only when the thermostat has opened is the lamp extinguished. It is thus a reliable indication of when the oven is drawing current.

It will be evident to those skilled in the art that many modifications may be introduced without departure irom the spirit of this invention, and I desire that the diagram and description shall be considered as illustrative only.- The invention is not limited, except by the express limitations in the claims or as required by the prior a1 I claim as my invention:

1. The combination with a three-wire circuit including two main wires and a neutral wire, of a pair of current-consuming devices, means including a control switch, a manual switch ior selectively connecting said devices to one of said main lines and for effecting connection of the control switch to the other main line, an indicator, and means including said control switch for connecting both said devices and one tenninal of said indicator to said other line through said manual switch, the other terminal of said indicator being connected to said neutral wire.

2. The combination with a three-wire circuit including two main wires and a neutral wire, of

a plurality of current-consuming devices, first switch means, means including second switch means for selectively connectingsaid devices to one of said main lines and for effecting connection of said first switch means to the other main line, an indicator, and means including said first switch means for connecting said devices and one terminal of said indicator to said other line through said second switch means, the other terminal of said indicator being connected to said neutral wire.

3. The combination with a three-wire circuit including two main wires and a neutral wire, 0! a plurality of heating elements, control means opening in response to predetermined temperature conditions, means including switch means for selectively connecting said elements to one of said main lines and for effecting connection of said control means, when closed, to the other main line, an indicator, and means including said control means, when closed, to! connecting said heaters and one terminal of said indicator to said other main line through said switch means, the other terminal of said indicator being connected to said neutral wire.

EDWIN H. LOCKWOOD.