US2708477A - Controls for combination gas-oil burners - Google Patents

Description

May 17, 1955 s Ru CONTROLS FOR COMBINATION GAS OIL BURNERS Filed Jan. 29, 1951 GAS FROM GAS VALVE SUPPLY FROM OIL SUPPLY 'ro UNE 2 7 J in 73 e9 81 7 78 H I 6 r 3) 2 PILOT 75 5| GAS SAFETY 77k 6j VALVE F8 SB I 9%; I -3:? 4* |2 77 89m4l 27 J 93f c 9| as OUTSIDE as Q T MR H c GOFETROL 90 g' 'g INVENTOR.

92 STEPHEN cRuM United States Patent CONTROLS FOR COMBINATION GAS-OIL BURNERS Stephen Crum, Edina, Minn., assignor to Minneapolis- Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application January 29, 1951, Serial No. 208,413 9 Claims. (Cl. 158-11) This invention relates to controls for combination gasoil burners and, more particularly, to a combination vaporizer-temperature responsive unit in combination with a valve and a switch.

While combination gas-oil burners are well known in the art, and a vaporizer type of such a burner broadly was known prior to my invention, the control means for said burners have heretofore been somewhat unsatisfactory in that the controls for said burners have been quite complicated and numerous, which resulted in troublesome and costly installations.

- One of the objects of this invention is to provide a compact, reliable, and inexpensive control device for burners of the above mentioned type.

Another object of the invention is to provide a combination vaporizer and temperature responsive control device for controlling the flow of oil to the vaporizer and converting said oil to gas for burning in a furnace.

Still another object of the invention is to provide a simple, yet sturdy and reliable, combined vaporizer and temperature responsive unit.

A still further object of the invention is to provide a control system for gas-oil burners that provides forthe burning of oil only when the vaporizer has reached a predetermined temperature and the outside temperature has lowered to a predetermined temperature.

Still further objects'of the invention will become apparent upon reading the following detailed description of the invention in conjunction with the accompanying drawing wherein:

Figure l is a schematic showing of one possible design of the invention; and

Figure 2 is a wiring diagram of the controls for a gasoil burner showing the control device of Figure 1 schematically in combination with other conventional burner controls.

Referring to Figure 1 of the drawing, a section of a furnace wall10 is shown as being apertured at 11 to receive a stainless steel tube 12, which forms a part of a temperature sensing unit of a control device generally designated by the reference numeral 8. The tube 12 is also a vaporizer for liquid petroleum gas and is supported in position over a gas burner 13 by means of a collar 14 surrounding said tubeand bolted to the furnace wall 10 by means of bolts 15. A screw 16 is screw threaded through the collar 14 and extends into a hole in the tube 12 to prevent relative movement between the collar 14 and the tube. The inner end of the tube 12 is closed by a plug 17 which is welded or otherwise secured in said end of the tube. Radially extending and aligned passages 18 and 19 through the lower walls of the tube 12 and collar 14 provide an outlet passage for the flow of vaporized oil from the vaporizer tube 12 through a conduit 20 to a nozzle 21 of the burner 13. Gas is supplied to a similar nozzle 21a from a gas supply through conduit 7. The outer end of the vaporizer tube 12 is threaded into a back wall 22 of a housing 9. A second tube 23, formed of a metal having a lower temperature coefficient 2,708,477 Patented May 17, 1955 of expansion than the metal of tube 12 and having an outside diameter smaller than the inside diameter of the tube 12, is connected by a rod 24 of the same material to the plug 17 so as to hold said second tube spaced from the inner wall of the tube 12. The rod 24 extends through the plug 17 and is welded or otherwise secured thereto. The rod 24 also extends into the adjacent end of the tube 23 and is welded or otherwise secured thereto. A hole 25 for the admission of oil to the vaporizer tube, extends radially through the lower wall of the tube 23 adjacent the end of the rod 24. The outer end of the tube 23 has an externally threaded portion 26, which terminates adjacent an annular flange 27 spaced outwardly from the outer end of the vaporizer tube 12. The outer end 26 of the tube 23 extends through a central opening in a flexible diaphragm 28, of any suitable material, and a nut 29 sealingly clamps the center portion of the diaphragm against the annular shoulder 27. The peripheral edge of the diaphragm lies in an annular recess 30 of the housing 22 and is sealingly clamped to said wall 22 by means of a bracket plate 31 having screws 32 passing through said plate, diaphragm 23 and threade into suitable holes (not shown) in the wall 22.

A removable wall section 33 for the housing 9 is secured to the housing by means of screws 34. Section 33 has an annular rib 35 formed on the inner wall thereof near the top thereof and an opening 36 coaxial with said rib 35 which extends through said wall 33 to form a valve seat 37 at the inner surface of said wall. A valve head 38 cooperates with said valve seat 37 to control the flow of oil from a supply conduit 39, through said valve seat 37, a passage 40 through said rib 35, and a flexible conduit 41 to the interior of tube 23. Said head 38 is screw threaded (not shown) or otherwise connected to a valve stem 42 which passes through a guide plate 43. The guide plate 43 is clamped to the peripheral edge of a diaphragm 44 by means of screws 45, which extend through'said plate 43 and diaphragm 44, and which are screw-threaded into rib 35. A collar 46- formed on the stem 42 enables the head 38 to clamp the center portion of the diaphragm 44 into sealing relationship with the stem 42 to thus prevent the flow of oil from the supply conduit 39 into the housing surrounding the rib 35.

Positioned on a wall of the housing 9, at the bottom 5 thereof, and secured thereto by screws 46, is an insulation tively stiff resilient pivot member 54 of general U-shape.-

The ends of two legs 55 thereof, one of which is shown in the drawing, are slidably positioned between two spaced pins 56 extending parallel to the plate 31 from cars 31b formed on said plate. Freely passing through an opening in the base of the U-shaped member 54, near the bottom edge thereof, is an adjusting screw 54a that is screw threaded in a threaded opening in a laterally offset portion 31a of the bracket plate 31. Positioned inwardly toward the legs 55 of the member 54, from the adjusting screw 54a, is a transversally struck-out knife-edge portion 54b which forms a fulcrum for a lever 57 to be presently de scribed. It is thus seen that by rotating the screw 54a the position of the fulcrum or pivot 54]) may be adjusted.

The above mentioned lever 57 has a depression 58 near its upper end which receives a pointed end 59 of the valve stem 42. The lower end of the lever 57 has an insulation strip 60 riveted thereto. Inwardly of a hole 61, adjacent Terminal screws 52 and 53 are provided on the,

said insulation strip and through which the adjusting screw 55 guidably passes, a trough or valley 62 is formed in the lever 5'7 at a point which engages the pivot 54b, to provide a pivotal connection between the lever 57 and the pivot 546. Located betweenthe valley 62 and the socket 58, is an opening 63 through which the threaded end 26 of the tube 23 extends. Adjustable nuts 64, having rounded surfaces, are adjustably positioned on opposite sides of the lever 57 so as to permit a slight amount of rocking of the lever 57 with respect to the tube 23. The nut 64 and the adjusting screw 54a provide the means for calibrating the control device and are so adjusted that, when the tube 12 is below the vaporizing temperature of the oil, the valve head 38 will be seated on the valve seat 37, cutting off the flow of oil to the vaporizer 12 through the tube 23' and hole 25. Secured to the lower end of the insulation strip 66 and extending downwardly between the contacts 59 and 51, is a contact arm 65 carrying contacts 66 and 67 that are adapted to engage contacts and 51, respectively. A lead wire 68 is electrically connected to the contact arm 65, as by soldering said wire thereto. The lead wire 68 is adapted to flex as the contact arm moves toward the right or left, as viewed in Figure 1, and is adapted to be connected in the control circuit, to be presently described. The flexible contact arms 48 and 49 are so adjusted that as the contact arm 65 moves towards the left, the contact 51 will remain in engagement with the contact 67 until after the contact 66 engages the contact 50. A short time thereafter the contact arm 48 will have been deflected toward the left a suflicient amount to permit the contact 67 to leave the contacts 51. As the contact arm moves in the opposite direction toward the right, the contact 50 will remain in engagement with the contact 66 until after the contact 67 engages contact 51. A short time thereafter, contact 66 will leave the contact 50 as shown in Figure l.

The above described control device is preferably used in a control system such as that shown in Figure 2. The secondary winding 69 of a transformer 70 is connected by line 71 to the fixed contact 72 of a room thermostat 73 through a conventional pilot safety means 74. The movable contact arm 75 of the room thermostat is connected through line 76 to the flexible lead 68 connected to the movable contact arm 65. The contact 51, generally known as a C or cold contact, is connected through a lead 77, adapted to be connected to the contact arm 49 by means of the connector screw 53, and line 78 to a conventional gas valve 79 preferably having a pressure regulator 79a attached thereto. The circuit to the gas valve 79 is completed through lines 80 and 81 back to the other side of the transformer secondary coil 69. The contact 50 is connected through lead 82, which is adapted to be connected to contact arm 48 by connector screw 52, and line 83 to a movable contact arm 34 of a conventional outdoor or outside temperature control 85, the details of which form no part of this invention. The outside temperature control may comprise a bimetal actuator 86 and a connecting link 87 between the free end of said bimetal actuator 86 and the pivoted contact arm 84. When the outside temperature is above a predetermined amount, the contact arm 84 is in engagement with a fixed contact 88 which is connected through line 89 to lead 77 and contact 51. Another fixed contact of the outside temperature control 90 is connected through line 91 to a conventional oil valve 92, which also preferably has a pressure regulator 92a associated therewith. The other side of the oil valve 92 is connected through line 93 to line 81 and, thus, to the secondary of the transformer.

Operation With the control device installed in a system such as that shown in Figure 2, and with the room temperature and the outside temperature above their respective control temperatures, the elements of the control device shown in Figure l and the control units of Figure 2 will be in their respective positions, as shown in Figure 2. That is, the

room thermostat will be open, contact 67 will be in engagement with contact 51 and contact arm 84 will be in engagement with contact 88. Thus, there will be neither gas nor oil flowing through the gas or oil valves, due to the fact that neither one of said valves is energized. Assuming that a flame is in existence at a pilot burner (not shown) for the main burner 13 of the furnace, a drop in the room temperature below its control point will complete a circuit from the movable contact arm 75 of the room thermostat, through contact 72, pilot safety 74, line 71, coil 69 of the transformer, line 81, line 80, gas valve 79, line 78, lead 77, contact 51, arm 65, lead 68 and line 76 back to the room thermostat 73. This will cause energization of the gas valve and opening thereof, to provide gas flow to the main burner, which will be ignited by the pilot burner. After the burner 13 has been in operation for a sufiicient time to heat the vaporizer tube 12 up to a temperature that will cause vaporization oil in the oil supply for said furnace, the tube 12 will expand suificiently more than the tube 23 and rod 24 as to cause the upper end of the lever 57 to move toward the right and cause opening of the valve 38. However, oil will not flow through the conduit 39 unless the oil valve 92 has become energized. Simultaneously with the moving of the valve 38 to its open position, the contacts 66 and 50 will close, followed by the opening of contacts 51 and 67. It will thus be seen that the gas valve 79 will not necessarily become deene'rgized by the opening of contacts 51 and 67 and the closing of contacts 50 and 66, due to the fact that a circuit to the gas valve 79 is maintained through contacts 66 and 50, lead 82, line 83, contact arm 84, contact 88, line 89 and line 78 to the gas valve. Therefore, unless the outside temperature is below the control point of the control 85, the burner 13 will continue to burn gas. However, should the outside temperature be below the control point of the control at the time the contact arm 65 moves from contact 51 to contact 50, or subsequent thereto, the contact arm 34 of the outside temperature control will break the circuit to the gas valve 79, upon leaving the contact 88, and will complete a circuit to the oil valve 92 through contact 90, line 91, valve 92, line 93 and line 81 to the secondary of the transformer, the circuit to the other side of the secondary through the room thermostat to the movable contact arm 65, contact 50, lead 82 and line 83 to arm 84 being closed at this time. Should the outside temperature rise above the control point of the outside control while the furnace is burning oil, the movable contact arm 84 will move back from contact and engage contact 88 to transfer the operation from oil to gas. Should the room thermostat become satisfied, with the furnace burning either gas or oil the circuits to both the gas valve and the oil valve will be broken, causing the shutting down of the main burner.

If the burner 13 remains off for a sufiicient time to cause the cooling of the vaporizer tube 12 below the temperature at which it would vaporize the oil admitted thereto, the contact arm 65 will move contact 66 away from contact 50 and contact 67 into engagement with contact 51, thus breaking the circuit to the contact arm 84 through which current must flow to energize the oil valve 92. It is thus observed that under these conditions 4 and regardless of the outside temperature, upon a call for heat by the room thermostat, the gas valve will be the first to open to cause burning of gas at least until the tube 12 reaches the temperature which causes opens ing of the oil valve and the supply of oil to the tube 12.

While I have described one possible form of the control device and one control system in which the control device may be used, it is deemed to be obvious to those skilled in the art that modifications may be made in both without departing from the spirit of the invention. It is, therefore, to be expressly understood that the scope of 1. A control system for a combination gas and oil burning furnace comprising an electrically operable gasvalve, an electrically operable oil valve, a control valve, an oil vaporizer having a temperature responsive element, a lever operably connected to said control valve and carrying a double-throw contact arm, a pair of spaced contacts on opposite sides of said contact arm, one of said contacts normally engaging said contact arm and being electrically connected to said gas valve, the other of said contacts being in a circuit of said oil valve which controls oil flow to said control valve, motion transmitting means between said temperature responsive element and said lever for simultaneously enabling said control valve to move to its open position and said contact arm to move into engagement with said other contact upon said vaporizer rising to a predetermined temperature, means adapted to be connected to an electrical source of power and including operating means for controlling the power, and an outdoor temperature responsive means having a movable contact arm and first and second fixed contacts, said movable contact arm being electrically connected to said other contact, said first contact being electrically connected to said one contact, and said second contact being electrically connected to said oil valve.

2. A control system for a combination gas and oil burning furnace comprising an electrically operable gas valve, an electrically operable oil valve, a control valve, an oil vaporizer having a temperature responsive element forming a part thereof, a lever operably connected to said control valve and carrying a double-throw contact arm, a pair of spaced contacts on opposite sides of said contact arm, one of said contacts normally engaging said contact arm and being electrically connected to said gas valve, the other of said contacts being in a circuit of said oil valve which controls oil flow to said control valve, motion transmitting means between said temperature responsive element and said lever for simultaneously enabling said control valve to move to its open position and said contact arm into engagement with said other contact upon said vaporizer rising to a predetermined temperature, means adapted to be connected to an electrical source of power and including operating means for controlling the power, and an outdoor temperature responsive means cooperable with said pair of contacts for switching the system from energization of the gas valve to energization of the oil valve when the outside temperature drops to a predetermined temperature.

3. In a control system for a combination gas and oil burning furnace, the combination comprising an electrically operable gas valve, an electrically operable oil valve, a control valve, an oil vaporizer, a temperature responsive element forming a part of said vaporizer, a lever operably connected to said control valve and carrying a doublethrow contact arm thereon, a pair of spaced contacts on opposite sides of said contact arm, one of said contacts normally engaging said contact arm and being electrically connected to said gas valve, and the other of said contacts being in a circuit including said oil valve, said temperature responsive element being operably connected to said lever for causing said control valve to move to its open position and said contact arm into engagement with said other contact upon said vaporizer rising to a predetermined temperature, and means adapted to be connected to an electrical source of power and including operating means for controlling the power.

4. In a control system for a combination gas and oil burning furnace, the combination comprising an electrically operable gas valve, an electrically operable oil valve, a control valve in fluid flow series with said oil valve, an oil vaporizer having a temperature responsive element forming a part thereof, a lever pivoted intermediate its ends, one end of said lever being operably connected to said control valve, the other end of said lever carrying a double-throw contact arm, a pair of spaced contacts on opposite sides of said contact arm, one of said contacts normally engaging said contact arm and being electrically connected to said gas valve, the other of said contacts being in a circuit of said oil valve and means between said temperature responsive element and said lever for simultaneously causing said control valve to move to its open position and said contact arm into engagement with said other contact upon said vaporizer rising to a predetermined temperature, and means adapted to be connected to an electrical source of power and including operating means for controlling the power.

5. The combination defined in claim 4 in combination with an outdoor temperature responsive means comprising a double-throw switch having a contact arm electrically connected to said other contact and a first contact electrically connected to said one contact and a second contact electrically connected to said oil valve.

6. In combination, an oil vaporizer comprising a first tube having a closed end and an open end, a smaller second tube disposed within said first tube with one end thereof being closed and connected to said closed end of said first tube and with the other end thereof being open and extending beyond said open end of said first tube, a hole in the bottom of said second tube near the closed end thereof, said second tube having a lower temperature coefiicient of expansion than said first tube, sealing means between said open end of said first tube and said second tube which permits relative axial movement therebetween, a valve body having a chamber therein containing a normally closed valve, conduit means between said valve chamber and said open end of said second tube, motion transmitting means between said open end of said second tube and said valve for enabling said valve to move to its open position upon said first tube rising to a predeter mined temperature, a pair of spaced contacts, a movable contact arm on said motion transmitting means positioned between said contacts for alternate engagement therewith when said motion transmitting means moves between its valve open and valve closed positions, and means for electrically connecting said contacts and contact arm to a controlled source of power.

7. In combination, an oil vaporizer comprising a first tube having a closed end and an open end, a smaller second tube disposed within said first tube with one end thereof being closed and connected to said closed end of said first tube and with the other end thereof being axially movable with respect to the open end of said first tube, a hole in said second tube within said first tube, said second tube having a different temperature coefiicient of expansion than said first tube, sealing means between said open end of said first tube and said second tube which permits relative axial movement therebetween, a valve chamber having a normally closed oil valve therein, conduit means between said valve chamber and said other end of said second tube, and motion transmitting means between said other end of said second tube and said valve for causing said valve to move to its open position upon said first tube rising to a predetermined temperature.

8. In combination, an oil vaporizer comprising a first tube having a closed end and an open end, a smaller second tube concentrically disposed within said first tube with one end thereof being closed and connected to said closed end of said first tube and with the other end thereof being open and extending beyond said open end of said first tube, a hole in the bottom of said second tube near the closed end thereof, said second tube having a lower temperature coeificient of expansion than said first tube, sealing means between said open end of said first tube and said second tube which permits relative axial movement therebetween, a normally closed oil valve, flexible conduit means between said valve and said open end of said second tube, and a lever engaged by said open end of said second tube and said valve for causing movement of said valve to its open position upon said first tube rising to a predetermined temperature.

9. In combination, an oil vaporizer comprising a first tube having a closedend and an open end, a smaller second tube disposed within said first tube with one end thereof being closed and connected to said closed end of said first tube and with the other end thereof being open and extending beyond said open end of said first tube, a hole in the bottom of said second tube intermediate the ends thereof, said second tube having a lower temperature coefficient of expansion than said first tube, sealing means between said open end of said first tube and said second tube which permits relative axial movement therebetween, a normally closed oil valve, conduit means between said valve and said open end of said second tube, and movable means between said open end of said second tube and said valve for permitting said valve to move toits open position upon said first tube rising to a predetermined temperature.

References Cited in the file of this patent UNITED STATES PATENTS

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