US1763573A - Thermostatically-actuated electric control - Google Patents

Description

June 10, 1930. w. w. WILLIAMS THERMOSTTICALLY ACTUATEP ELECTRIC QONTROL lNYEnTmR WALT E R W WILLIAMS EY'aa /w M Q A: TY

Filed Aug. 3, 1925 Patented June 10, 1930 UNITED STATES- PATENT OFFICE WALTER W. WILLIAMS, 0] BLOOMINGTON, ILLINOIS, ASSIGNOR TO WILLIAMS OIL-Or MATIG HEATING CORPORATION, OF BLOOMINGTON, ILLINOIS, A CORPORATION OF ILLINOIS THEBMOSTATICALLY-ACTUATED ELECTRIC CONTROL Application flled August 8, 1925. Serial No. 47,700.

This invention relates to improvements in electric controls and more particularly to a device of this character which is actuated thermostatically.

Devices of this character are used to great advantage in connection with domestic heaters or furnaces in which an electric current is employed to operate a motor to open and close dampers or for the purpose of operat ing a liquid fuel burner in connection with the furnace. It has been customary to apply devices of this character which are subjected to the temperature of the gas within the stack leading from the furnace and this type of control has received the commercial designation of stack control. Such devices have a portion extending within the stack containing thermostatic elements which will expand upon the increase of heat when the fire within the furnace is burning and contract when the fire goes out. The expansion and contraction of these elements are transmitted to a mechanism for closing and breaking the circuit for operating the motor.

It is an object of this invention to provide a device of this general character in which the actuating element is sensitive in its action and due to its construction will contract very rapidly, when the source of heat in the furnace has failed.

While a preferred form of this invention is illustrated upon theaccompanying sheet of drawing, yet, it is to be understood that minor detail changes may be made without de )arting from the scope thereof.

In the drawing Figure 1 is a view of an embodiment of this invention in side elevation with parts broken away and partly in section.

F igure 2 is a transverse sectional view taken upon the line 2-2 on Figure 1 looking in the ircction of the arrows.

Figure 1 illustrates this improved thermostatically actuated electric control ada ted to be applied to the stack or pipe lea' ing from a domestic heating furnace for the purpose of controlli the operation of an electric motor adapte to operate a domestic oil burner in connection with the furnace by closing or breaking the commercial electric circuit leading to the motor. The control is mounted upon a curved plate 1 adapted to be secured to the stack or metal pipe of the furnace, which is provided with a boss 2 extending on the exterior side adapted to receive and secure thereto by a set screw a bushing 3 surrounding the actuating portions of the control which extend through the bushing and through a similar shaped orifice in the stack or pipe.

he electric connections and operatin parts are mounted upon a circular meta plate 4 having a central circular opening 5 and a depending sleeve 6 adapted to receive the shouldered end of a tube 7 which extends through the bushing 3 into the interior of the stack or pipe leading from the furnace, which tube is similarly shouldered at the other end. A metallic bushing 8 of similar dimension to the depending sleeve 6 and havin a similar circular aperture passing themt irough surrounds the other or inner end of the shouldered tube 7. Another metallic tube 9 surrounds the do )ending sleeve 6, shouldered tube 7 and mshing 8 surrounding the inner end which tube 9 is terminated flush with the exterior of said bushing and is secured thereto and to the shouldered tube preferably by a pin 10 passing through the exterior tube 9 bushing 8 and interior tube 7. This outer tube is received snugly but is capable of movement within the bushin 3 secured to the attaching plate 1 and exten s under normal conditions flush with the adjacent side of the circular plate 4 carryin the electric connections. The surface of this plate 4 is recessed substantially one-half its thickness about the de ending sleeve. The shouldered tube 7 and t 10 surroundin outer tube 9 are constructed of metal of di erent coefficients of expansion, and are so arranged that u n the portion within the stack or pipe lea mg from the furnace being subjected to heat in an increased degree, the outer surrounding tube 9 will expand longitudinally and travel over the depending sleeve 6.extending into the recessed .portion of the underside circular plate 4. As there is an openin 5 in the center of this plate, which is pre erably of the same size as the inner diameter of the shouldered tube 7 and a similar opening in the bushing 8 at the other end of the shouldered tube, when the source of heat within the furnace fails the upward natural draft from the furnace through the stack will draw atmospheric air through these openings and as the heat decreases from the furnace the cool air drawn through these elements of the control will impart an increased rate of contraction to the sliding outer sleeve to its original or normal position.

The operating mechanism for making and breaking the electric circuit includes a post 11 secured to the outside of the outer surrounding tube 9 which extends'there beyond and enters through a cut-away portion 12 therefor in the adjacent circular plate 4 so that as the tube expands this post will be eX- tended beyond the upper surface of the circular plate and as the tube contracts the post will be Withdrawn. Two binding posts 13 and 14 are arranged on the upper surface of the circular plate 4 for receiving and securing the terminals of the leads 15 from the commercial source of the electricity to the motor. One terminal 13 is connected by a lead 16 to a fixed contact point 17 secured to and insulated from the same surface of the circular plate 4. The other terminal is connected by a lead 18 to a binding post of a movable contact 19 carried upon a plate 20 pivoted at one end to a bracket 21 extending upward from the same surface of the circular plate 4. The arrangement of the contacts 17 and 19 being such that upon movement of the pivoted plate the circuit will be closed or broken. The pivoted plate 20 is held by a spring 22 secured to the bracket to close the circuit between the contacts and is provided with an adjustable member 23 depending from the under side thereof, adapted to be engaged by the end of the post 11 carried on the outer sliding tube 9, which member is so adjusted that when the tube is in the normal or contracted position the circuit will be closed and upon expanding, when subjected to an increased heat within the stack or pipe leading from the furnace, the post entering above the upper surface of the circular plate will lift the depending member 23- and rotate the contact carrying plate 20 about its pivot to break the circuit. It is preferable to provide a bracket 24 attached to the u per surface of the circular plate 4 by the xed contact securing means which bracket extends above the moveable contact binding post and is provided with an adjustable insulated stop.

25 adapted to prevent abnormal movement of the moveable contact. 4

It is preferable to mount the moveable contact 9 upon a shaft 29 which passes through an aperture in the pivoted plate 20 which shaft is provided with a fixed collar 30 upon the under-side of the plate 20 to prevent further upward movement through the plate. This shaft which mounts the binding post 31 at its upper end is surrounded by a lava insulating block 32 threaded into the plate 20 and of less height than the distance between the binding post and the upper surface of the pivoted plate when it is in contact with the shoulder on the contact carrying shaft. It is preferable to provide opposite sides of the lava block with fiat longitudinal surfaces and also a plate of spring metal secured to the binding post 31 with depending side portions 33 bent back upon themselves to frictionally engage the opposite flat surface of the lava block with a sliding contact. By this construction as the post 11 lifts the pivoted plate 20 upon expansion of the outer tube 9, the contacts 1}) and 17 are separated and the circuit broken. As the heat in the furnace increases the tube 19 will continue to expand and the post 11 will continue to lift the contact carrying end of the pivoted plate 20. The initial movement of the plate 20 has carried the moveable contact binding post into an engagement of the stop 25; further movement will cause the plate 20 to slide over the contact carrying shaft 29 carrying the lava block 32 with it until the top of the lava block engages the underside of the binding post 31. Upon contraction of the tube 9 and Withdrawal of the post 11, the spring 22 will cause the free end of the pivoted plate 20 to descend. The lava block 32 being at tached to the plate and having frictional contact with the depending side portions 33 of the metal plate 31 secured to the upper end of the shaft 29 of the moveable contact will cause this shaft to descend with the movement of the plate 20 until the contacts engage, the plate 20 descending over the shaft thereafter until the underside is engaged by the collar 30. By this contraction it is seen that the frictional contact between the lava block and depending arms of the plate 31 carried on the upper end of the moveable contact shaft will cause the contact to move with the plate 20 upon an initial upward movement, breaking the circuit, and likewise will cause the contact carrying shaft to move downward with the plate 20 simultaneously with the withdrawal of the post 11 upon the contraction of the tube 9. By the proper adjustment of the member 23 carried on plate 20 which is engaged upon expansion by the post 11 and by the proper adjustment of the stop 25 adapted to be engaged by the upper end of the moveable contact carrying shaft 29, the circuit may be broken at a predetermined temperature of the interior of the stack, and moving of the contact carrying post away from the fixed contact may also be limited at a higher predetermined temperature, so that upon a denism 1t 1s preferable to provide a cylindrical tion; also will cause the contact carrying post to descend simultaneously with the plate and engage the fixed contact post closing the circuit at once without delaying until the temperature has decreased below the predetermined amount to which the stop has been adjusted. v

To protect the switch parts and mechahousing 26 about them secured to the circumference of the circular plate 4,which housing is provided with apertures 27 around its sides and top for the admission of atmospheric air and for the leads 15 of the electric circuit to, pass therethrough.

sired.

While the leads 16 and 18 may be of commercial insulated ,wire. it is preferred to mount one or more insulated beads 28 on each lead to prevent the wire from contacting with any of the'metal parts of mechanism.

Reference has. been made to the articu-' lar construction providin what might be called an air duct throng the electric operating and thermostatic actuating means, also that the shouldered tube 7 and the outer surroundin tube 9 are constructed of materials having different coefficients of'expansion. It is preferable to form the shouldered tube 7 of iron and the outer surrounding tube 9 of brass, so that the brass tube fire in the furnace goes out.

\Vhile this control has been described as having the thermostatic elements entering into the stack leadingfrom the furnace of a domestic heater, it is obvious that. the control may be installed wherever desired, so long as the thermostatic elements are subjected to the variations in temperature within the furnace roper and may be applied to the furnace 001', for example, if so de- What I claim is 1. A stack control device for electrically operated heating furnaces comprising an electric circuit making and breaking mechperature therein, said mechanism comprisanism mounted upon the exterior of the. stack having thermostatigactuating members for said mechanism entering the'interior 0f the stack and subjected to the variations of teming a fixed contact, and a moveable contact a normally closing the circuit, said,moveable contact carried on a plate having adjustable means adapted to beengaged upon the expansion of a thermostatic member and at a predetermined temperature within the stack be moved to break the circuit, said moveable contact having a slideable engagement with said plate and adjustable means to limit the movement of said contact with said plate away from said fixed contact and allowing further movement of the plate in that direction, and means causing the contact to always move with the pl'ate. inthe direction of the fixed contact. v

2. A stack control device for electrically operated heating furnaces, comprising an electric circuit making and breaking mechanism mounted upon the exterior of the stack having thermostatic actuating membersfor said mechanism entering the interiorof the stack and subjectedto the variations of temperature therein, said mechanism comprising a fixed contact, and a spring pressed pivoted plate adapted to be engaged by one of the thermostatic elements and caused to rotate about its pivot upon expansion and contraction of said element, a contact carried on a shaft passing through the free end of said plate having a slideable and frictional engagement with said plate, a stop over said shaft limiting the movement of'the shaft in that direction, said frictional engagement causing the contact to move simulshaft in relation to said plate.

WALTER W. WILLIAMS.

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