US2635003A - Thermostatic element - Google Patents

Description

April 14, 1953 Filed NOV. 20, 1950 R. L. PERL THERMOSTATIC ELEMENT 2 SHEETS- SHEET l April 14, 1953 F@L L PERL 2,635,003

THERMOSTATIC ELEMENT Filed Nov. 20, 1950 2 SHEETSSHEET 2 JNVENTOR. i? z Cha/'Q7 A Per! BZ@- HJM@ Patented Apr. 14, 1953 UNITED STATELS PATENT OFFlCE THERMOSTATIC ELEMENT Richard L. Perl, Galion, Ohio, assignor to The Tappan Stove Company, Mansfield, Ohio, a

corporation of Ohio 6 Claims. 1

This invention relates to improvements in thermostatic elements oi the monometallic type.

Thermostatic elements of this type have a large number of uses but are especially adapted for use in ignition and control systems for the gaseous fuel burners of cooking ranges which einploy a gaseous fuel pilot burner by which the main burners are ignited and/ or controlled. In systems of this character the llame from the pilot burner impinges on the thermostatic element and causes it to operate a valve, an electric switch or other shiftable element. Consequently it is necessary to provide a thermostatic element which is not affected by the ambient temperature but depends upon the application of localized heat for actuation. It is also necessary that the element be so constructed that its life and utility will not depreciate ydue to the constant application of a name thereto.

The embodiment of the invention disclosed herein is a one piece sheet metal stamping having two legs disposed at right angles to each other which are rigidly secured to iixed supports, and an outwardly extending arm the free end of which is adapted to be operatively connected to a shiftable control member.

In the drawings the invention is illustrated in connection with an automatic ignition system for a pair of spaced top burners of a cooking range. A gaseous fuel pilot burner is disposed between the main burners. It is ignited by an electric ignition element and the main burners are ignited by the pilot burner through ila-sh tubes which extend from the main burners into close proximity with the pilot burner. The supply of gas to the pilot burner is controlled by the valves for the main burner. The opening of any of the main burner valves to supply gas to a main burner will also admit gas to the pilot burner. The electric ignition element is in an electric circuit which includes a normally closed switch and a plurality of normally open switches. There is a normally open switch operatively associated with each burner valve in such a manner that the opening of the valve will close the switch, and conversely the closing of' the valve will open the switch. The normally closed switch is arranged to `be opened by a thermostatic element which is mounted in position to be heated by the pilot burner after it has been ignited by the electricl ignition element. The opening of the normally closed switch will break the circuit to and (ie-energize the electric ignition element which need not be energized after the pilot burner has been ignited. In operation it is only necessary to open the selected burner valve. The opening of the valve admits gas to the main burner and to the pilot burner and closes the normally open switch associated therewith. The closing of the normally open switch will make the circuit to and energize the electric resistance element which will then ignite the 4pilot burner. The pilot burner will ignite the main burner through its flash tube, and will heat the thermostatic element, and the thermostatic element when heated will open the normally closed switch and break the circuit to and de-energize the electric resistance element. In the event the pilot burner should be extinguished for any reason while the gas is still turned on the thermostatic element will cool and close the normally closed switch which will re-energize the electric resistance element and re-ignite the pilot burner.

One of the objects of theinvention is to provide a thermostatic element which may be quickly, easily and inexpensively formed from regular stock sheet metal.

Another object of the invention is to provide thermostatic element of this type in which the life and utility thereof will not depreciate due to the constant application of a flame thereto.

Other and more limited objects of the invention will be apparent from the. following specification and the accompanying drawings forming a part thereof in which:

Fig. l is a diagrammatic layout showing my improved thermostatic element incorporated in an automatic ignition system for the top burners of a cooking range;

Fig. 2 is an enlarged top plan View ofthe removable control unit;

Fig. 3 is a longitudinal section taken on the line 'fl-3 of Fig. 2; and

Fig. 4 is a transverse section taken on the line 4-6 of Fig. 2.

Referring now to the drawings by reference characters, the numerals l and 2 are applied to a pair of spaced top burners of' a cooking range. Gaseous fuel is supplied to the burner l, from a supply manifold 3, through its mixing tube 4; and to the burner 2, from the manifold 3, through its mixing tube 5. A pair of cutoff valves il and 'l control the supply of gas to the burners l and 2, respectively. A pilot burner 3 is suitably mounted between the free ends of a pair of aligned flash tubes 9 and lll which are carried by the burners l and 2, respectively. Gaseous fuel is supplied to the pilot burner 8 from the manifold 3 through the valve l and the conduit il or through the valve and the conduits i2 and il. The cut-off valves B and 'I are so constructed that when either one is turned on to supply gas to one of the main burners l and 2 gas is also supplied to the pilot burner B. rlhe pilot burner 8 is ignited by an electric resistance ignition element I3 when it is energized, and the main burners I and 2 are ignited by the pilot burner 8 through the flash tubes 9 and I5. The electric ignition element I3 is mounted in operative relation to the pilot burner 8 on an insulating block It of a removable control unit generally indicated by the numeral I5. The energization of the electric ignition element I3 is controlled by a pair of normally open switches I5 and Il and a normally closed switch I8. The normally closed switch I is operatively associated with the valve 6 and comprises, the contacts I8 and 28 and the bridging conductor bar 2 I. The switch I6 is adapted to be closed through the medium of a cam section 22 carried by the valve stem 23 of the valve 6 and a link 2li simultaneously with the opening of the valve 8 and to be opened simultaneously with the closing of the Valve 5. The normally open switch I 'I is operatively associated with the valve 'I and comprises the contacts 25 and 25 and the bridging conductor bar 21. It is adapted to be closed through the medium of a cam section 28 carried by the Valve stem 29 of the Valve 'I and a link 3!) simultaneously with the opening of the Valve I and to be opened simultaneously with the closing of the valve The switch I8 is incorporated in the control unit I5 and is adapted to be opened by a thermostatic element 3l which is also incorporated in the control unit I5 in position to be heated by the flame from the pilot burner 8. The specific construction of the control unit I5 and the component parts thereof will be described in detail hereinafter.

In operation it is only necessary to turn on the control valve of the selected main burner. The turning on or opening of the valve will close the associated normally open switch I6 or Il and supply gas to both the main burner and the pilot burner. The closing of the switch I5 or il' will make the circuit to and energize the electric ignition element I3 which will then ignite the pilot burner. The main burner will then be ignited through the flash tube by the pilot burner. f

After ignition the pilot burner will also heat the thermostatic element 3| which after being heated will open the normally closed swtich I8 and maintain it open as long as the thermostatic element 3| is heated by the pilot burner. of the normally closed switch i8 breaks the circuit to and de-energizes the electric ignition element I3 which need not remain energized after the pilot burner has been ignited. If after one main burner has been ignited the other main i burner is turned on it will be ignited through its flash tube by the pilot burner which has already been ignited, it being understood that the pilot burner is arranged to burn as long as either of the main burners is turned on. If the pilot burner should be extinguished for any reason while either of the main burners is turned on the thermostatic element SI will immediately cool and allow the switch I8 to close which will reestablish the circuit to and re-energize the electric ignition element I3 which will then reignite the pilot burner 8.

The electric circuit which includes the electric ignition element I3, the normally open switches I 6 and I'I and the normally closed switch I8 will now be traced, assuming first that the burner I is turned on by opening the valve 6. The opening of the valve 6 will supply gas to the main burner I and the pilot burner 8 and will close the normally open switch I6. As soon as The opening the switch I6 is closed current will flow from one side 32 of the line through the leads 33 and 34 to the Contact I 9 of the switch I5 and through the bar 2l to the contact 28. From the contact 25 the current will flow through the lead 35 to the terminal 38 of the electric resistance ignition element I3 and then through the ignition element I3 to the terminal 3l thereof. From the terminal 3l the current will flow through the lead 38 to the normally closed switch I8, thence through the switch I8 and back to the other side 39 oi the line through the lead 45, completing the circuit to and energizing the ignition element I3, which will remain energized until the thermostatic element opens the switch I8 and breaks the circuit. Assuming that the main burner 2 is first turned on by opening the valve 'I, the opening of the valve I will supply gas to the main burner 2 and the pilot burner 8 and close the normally open switch il. As soon as the switch I'I is closed current will iiow from the side 32 of the line through the lead 33, switch I'I and lead "il to the lead 35. From the lead the current will flow through the ignition element I3, switch I8 and back to the other side 39 of the line as previously described. The turning on of either one of the main burners after the other main burner has been turned on and ignited along with the pilot burner will not energize the electric ignition element I3 as the circuit thereto cannot be completed since the thermostatic element 3i is holding the switch I8 open.

The removable control unit I5 includes a frame 50, the electric ignition element i3 and the insulation block Ill, the normally closed switch I8, and the thermostatic element SI. The frame 55 is formed of thin sheet metal and comprises a base 5I having a pair of spaced parallel upwardly extending vertical side walls 52 and 53 formed integrally therewith. The inner ends of the side walls 52 and 53 are connected by a vertical end wall 55, and the upper edges of the side walls 52 and 53 are connected by a transverse brace 55 which is disposed rearwardly of the end wall 54. The base 5I is cut away or apertured adjacent the end wall 54 as indicated at 56 and the side walls 52 and 53 are notched opposite the cut away section of the base as shown at 58. The other end of the base 5I eX- tends beyond the free ends of the side walls 52 and 53 and terminates in a downward step 5S which is removably mounted in a slot 6B in a xed supporting member SI. The opposite end of the frame 55 rests on the ash tubes 9 and I5 with the flash tubes 9 and Iii engaging the notched portions 58 of the side walls 52 and 53. When in position the cut away section 56 of the frame base 5I is disposed over the pilot burner 3 so that when it is ignited it will project a flame up between the side walls 52 and 53. The electric resistance ignition element I3 is removably secured between the terminals 36 and 31 carried by the block I5 of insulating material. The block I5 is mounted between the side walls 52 and 53 adjacent the transverse brace 55 in position to maintain the ignition element I3 in operative relation to the pilot burner 8.

The normally closed switch I8 is secured to the base 5I between the side walls 52 and 53 a short distance inwardly from the step 58 and comprises a stationary Contact 62 and a movable contact 63. The stationary contact 62 is adjustably mounted in a sleeve B5 which is mounted in a, plate 65 of insulating material beneath an aperture 66 in the base 5I. The plate 65 is secured to the under side of the base 5| by rivets 67 and SS. The movable contact 53 is secured to the under side ef the top section 99 of a U- shaped spring member which normally biases the Contact 63 into engagement with the stationary Contact 62. The bottom section 79 of the spring member is secured to the upper side oi the base 5l by the rivets 61.

The thermostatic element 3| is formed from a single piece of sheet metal and comprises a vertical leg 76, a horizontal leg 'H and an arm 72. The upper end or the vertical leg 70 is welded to the Linder side or the transverse brace 55 at 73. The horizontal leg l! extends outwardly from the lower end of the Vertical leg 'i6 across the cut away section 56 of the base 5i above the pilot burner 8 in position to be heated thereby and has its free end welded to the end wall 54 at 74. The arm 'i2 extends outwardly from the vertical leg 79 opposite the horizontal leg li. The side walls of the legs 'I0 and 1i and the arm 72 are all disposed in substantially the same plane, and the lower edge of the arm 'l2 is turned at a right angle to the side thereof to provide a stiiening rib 75. The free end 76 of the arm 72 is disposed under a tongue 'I7 carried by the top section 69 of the U-shaped spring member of the normally closed switch I8. After the pilot burner has been ignited by the electric ignition element I3 the pilot burner flame will impinge on and heat the horizontal leg 'H of the thermostatic element 3|. The heating of the leg 'H will elongate it which will fiex the arm 72 about the weld 'I3 and cause the free end 'l1 of the arm 72 to move upwardly and lift the contact B3 out of engagement with the stationary contact 62.

The automatic ignition system shown and described herein in connection with my improved thermostatic element forms no part of the present invention but constitutes the subject matter of my co-pending application Serial No. 196,681, led November 20, 1950.

From the foregoing it will be apparent to those skilled in this art that I have provided a very simple and efcient mechanism for accomplishing the objects of the invention.

It is to be understood that I am not limited to the specific construction shown and described herein as various modifications can be made therein within the spirit of the invention.

What is claimed is:

1. A monometallic thermostatic element comprising a single imperforate piece of sheet metal having a vertical leg, a horizontal leg extending outwardly from the lower end of said vertical leg, and an arm extending outwardly from the lower end of said vertical leg opposite said horizontal leg, the outer ends of said legs being rigidly secured to fixed supporting means, and the free end of said arm being adapted to operatively engage a shiftable member and to ilex upwardly when heat is applied to said horizontal leg.

2. A thermally responsive control unit comprising a frame having a base, a pair of spaced side walls secured to and extending upwardly from said base, an end wall extending between said side walls, a transverse brace spaced from said base secured to and extending between said side walls rearwardly of said end wall, an aperture through said base adjacent said end wall, a monometallic imperforate thermostatic element having a vertical leg rigidly secured to said brace and extending downwardly therefrom, a horizontal leg integral with said vertical leg extending outwardly from the lower end of said vertical leg across said aperture and having the outer end thereof rigidly secured to said end wall, and an arm integral with said vertical leg and extending outwardly from the lower end thereof opposite said horizontal leg, the free end of said arm being adapted to operatively engage a shiftable member and to iiex upwardly when neat is applied to said horizontal leg.

3. A thermally responsive control unit comprising a frame and a monornetallic imperforate thermostatic element carried by said frame, said thermes-tatie element being formed from a single piece of sheet metal and comprising a vertical leg having the upper end thereof rigidly secured to said frame, a horizontal leg extending outwardly from the lower end oi said vertical leg and having the outer end thereof rigidly secured to said frame, and an arm extending outwardly from the lower end of said vertical leg opposite said horizontal leg, the free end of said arm being arranged to operatively engage a shiftable member and to flex upwardly when heat is applied to said horizontal arm.

4. A monometallic thermostatic element comprising a single imperforate piece of sheet metal having a vertical leg, a horizontal leg extending outwardly from the lower end of said vertical leg, and an arm extending outwardly from the lower end of said vertical leg opposite said horizontal leg and having the lower edge thereof turned at an angle to the side thereof to provide a stiiiening rib, the outer ends of said legs being rigidly secured to xed supporting means, and the free end of said arm being adapted to operatively engage a shiitable member and to flex upwardly when heat is applied to said horizontal leg.

5. A monometallic thermostatic element comprising a single imperforate piece of sheet metal having a vertical leg, a horizontal leg extending outwardly from the lower end of said vertical leg, and an arm extending outwardly from the lower end oi' said vertical leg opposite said horizontal leg, the sides of said legs and said arm being disposed substantailly in the same plane, the outer ends of said legs being rigidly secured te xed supporting means, and the free end of said arm being adapted to operatively engage a shiftable member and to flex upwardly when heat is applied to said horizontal leg.

6. A monometallic thermostatic element comprising a single imperforate piece of sheet metal having a vertical leg, a horizontal leg extending outwardly from the lower end of said vertical leg, and an arm extending outwardly from the lower end of said vertical leg opposite said horizontal leg with the lower edge thereof turned at an angle to the side thereof` to provide a stilening rib, the sides of said legs and said arm being disposed in substantially the same plane, the outer ends of said legs being rigidly secured to fixed supporting means, and the free end of said arm being adapted to operatively engage a shiftable member and to ex upwardly when heat is applied to said horizontal leg.

RICHARD L. PERL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Re. 22,688 Higley Nov. 6, 1945 2,080,385 Congdon May 11, 1937 2,483,939 Schickler Oct. 4, 1949 2,487,963 Cerny Nov. 15, 1949

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