US2370891A - Draft control device for oil burners - Google Patents

Description

March 6, 1945 J. E. THORNQUIST 2,370,391

DRAFT CONTROL DEVICE FOR OIL BURNERS Filed May 25, 1941 Jawi INVENTOR BY W ATTORNEY v the furnace.

Patented Mar. 6, 1945 UNITED STATES PATENT OFFICE My invention relates to a draft control for oil burners, wherein it is desired to provide a means of cutting off the flow of air to an oil burner when the same is not in operation.

In the use of oil burners it is common practice -to provide a fan or other means for providing a forced draft for the furnace at the time the oil burner is in operation. This forced draft of air is provided to support combustion and to permit all of the oil to be burned. The fan is ordinaril connected to an air inlet which is open at all times. When the oil burner is not in operation the natural draft in the chimney causes a. constant flow of air through the furnace. This flow of cold air into the furnace cools the furnace much more quickly than would otherwise be the case. The air flowing through the furnace merely rises up through the chimney and is wasted.

It is the object of my invention to provide a means of cutting on the flow of air to the oil burner when the oil burner is not in operation. Thus during the time the oil burner is not throwing a flame into the furnace the air is kept from entering the lower portion of the furnace. Thus there is not a constant flow of cold air through the furnace, enabling the furnace to keep warm for a longer period of time.

It is an object of the present invention to provide a check valve or butterfly valve which is so devised as to open when the oil burner fan is in operation, but which will clos when the fan is not in operation. Thus as soon as the oil burner and the fan creating a draft therefor starts into operation, the valve opens to admit air. However, as soon as the fan ceases operation, the valve closes and the air suppl to the furnace is cut off.

It is a feature of the present invention to provide a draft of air which is warmer than that usually supplied to the oil burner. I prefer to take the air from a point substantially spaced from the floor and preferably near the door of As a certain amount of heated air escapes from the furnace and as the fair surrounding th furnace is at a slightly higher temperature than air at a greater distance from the furnace, the air which is drawninto the furnace by the fan is warmer than would otherwise be the case. Providing warm air for the operation of the oil burner is advantageous as less heat is required to heat the air, and accordingly more heat may be used to actually heat the furnace.

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intake opening of the air. Thus, if too much air is being supplied to the furnace my valve may be set so that less air would enter. through the same. By this means 1 provide a draft regulating device in conjunction with the draft closing device so that one apparatus will serve two purposes.

It is a feature of my invention that my valve for controlling the draft to the oil burner may be either in the form of a balanced butterfly valve, which is open by a reduction in air pressure on one sideof the same, or may be opened by a check valve. In either instance gravity provides the valve actuating mechanism.

A further feature of my invention resides in the fact that my valve may be regulatedto vary the It is a further feature of my invention that my draft control may be simply manufactured and may be constructed to fit virtually any oil burner on the market. This adapting means is necessary to equip each construction of oil burner to my draft control device, but once this has been done a considerable saving in fuel costs will be noted.

These and other objects and novel features of my invention will be more clearly and fullyset forth in the following specification and claims.

In the drawing forming a part of my specifica-. tion: i

Figure 1 is a side elevation view of an oil burner in position before a furnace, and my draft control device attached thereto.

Figure 2 is an elevation view of the draft control device showing the construction thereof.

Figure 3 is a sectional view through the draft control device, the position of the section being indicated by the line 3-3 of Figure 2.

Figure 4 is a cross sectional view through the draft control device of Figure 2, the position of the section being indicated by the line 4.4 of Figure 2.

Figure 5 is a diagrammatic view of a modified form of valve construction.

Figure 6 is a bottom plan view of the valve construction illustrated in Figure 5.

Figure 7 is a cross sectional view through, the valve of Figures 5 and 6, the position of the section being indicated by the line 1-1 of Figure 6.

The furnace A may be of any desirable type and is shown having a lower opening l0, an inspection door II, and a clean out door I 2. The opening I0 provides an ash pit opening when the furnace A is used to burn coal. In. the present instance, however, where an oil burner is used the opening I0 is closed by a closure plate II, having an opening therethrough in communication with an air and fuel duct l4.

and inexpensively" Various types of burners are constructed in diiierent manners so that the burner construction illustrated is merely diagrammatic. The burner B is supported from a base 15 on the floor US by means of standards l1. An oil supply line i9 delivers oil to the burner which may be provided with a suitable float device 20. The air inlet duct 2| is provided with a suitable fan or blower, as illustrated, which forces air through the duct l4 and into th lower portion'of the furnace A when the burner is in operation. Normally the end of the inlet duct 2| is open to admit air into the duct at all times. In the present instance, however, the inlet duct is closed by means of a hollow duct closure 22 which is con-' nected by the tapered conduit 23' tothe conduit 24. An elbow 25 supports the pipe or conduit 26, which supports the small and of a reducer 21. A hollow cylindrical casing 29 is provided for the valve C, which is best illustrated in Figures 2, 3, and 4 of the drawing. It will be noted that the valve C is of the butterfly type and is positioned adjacent the front of the furnace A to collect relatively warm air.

As best illustrated in Figures 2, 3, and 4 of the drawing, a flat ring 30 is provided with a cylin drical sleeve portion 3| of a size to fit within the cylindrical casing 29. An end flange 32 extends over the end of the casing 29 to hold the ring 30 in proper position. The ring 30 provides an aperture of a size slightly reduced with respect to the size of the casing 29, and this aperture is normally closed by the butterfly valve 33.

The butterfly valve 33 is substantially circular. in shape and the edge thereof tapers downwardly and inwardly at the top 34 and also at the bottom 35. This tapered edge limits the pivotal movement of the butterfly valve 33 on its pivots 36.

A bracket 31 is secured to the butterfly valve 33 on one side of the vertical center thereof, and above the horizontal center. The bracket 3'1 is secured to the valve 33 by bolts 39, or other suitable means. The bracket 31 supports a pivot 36 which projects outwardly beyond the bracket and which engages between the body of the'ring 30 and a strip 40 cut from the body of the ring and bent outwardly.

A bracket 4| is secured to the valve 33 in oppositely disposed relation to the bracket 31 and is fastened in place by any suitable means, such as the bolts 42. A pivot 36 is supported by the bracket 4| and extends outwardly beyond the bracket to engage between the body of the ring 36 and a strip 43 cut from the ring 30. The pivots 36 supported by the brackets 31 and 4| are aligned and permit the valve to pivot with respect to the ring 30.

The bracket 4| is similar to the bracket 31 with the exception that it is longer than the bracket 31 to accommodate the adjusting bolt 44. The adjustirg bolt 44 is provided with an operating end 45 bent at right angles to the body of the bolt 44 by means of which the bolt may be rotated.

Secured to the rear surface of the ring 30 by any suitable means, such as the bolts or rivets 46, I provide a bracket 41 which includes an arm 49 extending rearwardly from the ring, and provided with an end 50 which is bent at right angles from the arm 49 to extend inwardly toward the center of the housing 29. This arm 49 and end 50 are so devised as to provide a stop for the butterfly valve 33. Thus as the butterfly valve 33 swings inwardly, as disclosed by the dotted outline in Figure 4 of the drawing, the stop bolt 44 will strike the end 50 of the arm 49 to limit pivotal movement. In this manner the opening of the butterfly valve 33 may be regulated.

Near the top of the valve 33 I provide a threaded stud 5|, which extends inwardly from the valve and which is secured thereto by nuts 52. A weight 53 is threaded on the stud 5| and this weight is adjustably supported so as to vary the differential pressure necessary to swing the butterfly valve 33 into open position.

Inoperation, when the fan of the oil burner B starts into operation a reduction in pressure is experienced within the fan inlet which is secured to the housing 29. Accordingly the atmospheric pressure surrounding this compartment acts to swing thebutterfly valve 33 into the position illustrated in. dotted outline in Figure 4 of the drawing. As long as the fan of the oil burner continues in operation the butterfly valve 33 will remain in the inclined position shown in dotted outline inFigure 4 to permit air to enter the oil burner-,

As soon-as the fan of the burner stops its rotation the butterfly'valve 33 swings closed, stopping the flow of air into,thefurnace and thus preventing thecooling of the interior of the furnace by adraft of cool air passing therethrough.

In Figures 5, 6, and '1 of the drawing a modified form of construction is illustrated. In this form of construction the air'inlet pipe to the oil'burncr is indicated, in general by the numeral 54. This air inletpipe has circumferential openings therein, which are covered by the enclosing casing 55.

' illustrated in Figures 6 and '1 Thecasing 55 1s, preferably formed in two parts, splitl'at-56, so that the housing may be readily clamped over the inlet openings in the pipe 54. The interior of the hollow casing 55 is connected to the hollow pipe or conduit 51,which are connected by the elbows 59 and 60 to the small end ofa-reducer 6|. A valve casing 62, which is hollow and cylindrical, is secured to the large end of the reducer 6|.

The valve provided in the housing 62 is best of the drawing. A ring 63 is provided with a cylindrical flange 64 thereupon, which terminates in an edge flange 65. A bridg strip 66 is secured by suitable means, such as the bolts or rivets 61, to the lower surface of the ring 63. A central bearing 69 is provided on the bridge strip 66, and a sleeve 10 is. secured by any suitable means, such as the head screw 1|, to the bearing 69. The upper extremity of the sleeve 10 terminates in a circular flange or disc 12, which is provided with apertures 13 therethrough. I

Within the sleeve", I provide a rod 14 which is longitudinally slidable within the sleeve 10. A collar 15 lsprovided near the lower extremity of the rod 14 to limit slidable movement of the rod in an upward direction. A shoulder 16 is provided on the rod 14 near the upper end thereof. and the disc-shaped end 11 of a cylinder 19 is clamped between the shoulder 16 and a nut 8|] on the rod 14. The cylinder 19 therefore moves with the rod 14.

A ring-shaped valve disc 8| is secured to the flange 82 of the cylinder 19. The valve disc 8| has an opening therethrough, which is of approximately the same size as the diameter of the cylinder 19. The flange 12 in the cylinder 19 and a valve plate 83 loosely encircling the rod 14 above the flange 12 acts to close the opening 13 when the valve disc 8| and cylinder 19 is in elevated position and tends to close.

In operation, when the oil burner fan starts into acts as a piston with-- operation a reduction in pressure is experienced within the housing 82 so that the atmospheric pressure surrounding this housing raises the valve disc 8|. The cylinder I9 raises with the valve disc 8| andln this upward movement of the valve disc 8| the valve plate 83 raises slightly to permit air to flow readily through the apertures 13' in the flange I2.- Thus the valve disc 8| may raise without difliculty and air may enter the oil burner. When the oil burner fan ceases operation the suction acting upon the valve disc 8| decreases and the weight of the disc 8| tends to close the same. Air has been drafted within the cylinder 19 between the closed end 11 thereof, and the flange 12. The tendency for the valve disc 8| to lower tends to compress the air within the cylinder I9, thus pressing the valve plate 88 against the flange 12. Accordingly the lowering of the valve disc 8| is retarded and the valve disc 8| drops gradually, thus providing suflicient air to pp rt combustion until the fan is entirely stopped.

In the use of my valve for closing the draft to oil burners I have found that a considerable percentage of fuel may be saved through the use of this device. I have found that because of the cutting off of the stream of cool air flowing through the furnace when the oil burner is not in use longer periods of time elapse between successive operations of the oil burner, resulting in a considerable saving in fuel.

In accordance with the patent statutes, I have described the principles of construction and operation of my draft control device for oil burners, and while I have endeavored to set forth the best embodiments thereof, I desire to have it understood that these are only illustrative of a means of carrying out my invention, and that obvious changes may be made within the scope of the following claims without departing from the spirit of my invention.

I claim:

1. A draft control for a furnace having an inspection door at a point spaced from the bottom thereof, an oil burner casing extending into the furnace near the bottom thereof, and a draft creating fan forming a part of said oil burner, an inlet to said fan including an upwardly extending conduit extending substantially vertically from said draft creating fan, an elbow on said upwardly extending conduit, a horizontally extending conduit extending toward the inspection door of the furnace, a. housing secured to the end of said horizontally extending conduit, said housing having an open side therein, a butterfly valve mounted in said open side, said butterfly valve being movably mounted to open when suction is created by said fan and to close said open ide when said fan is not in operation.

2. A draft control for a furnace having an inspection door at a point spaced from the bottom thereof, an oil burner casing extending into the furnace near the bottom thereof, a draft creating fan forming a part of said oil burner to force air through said casing, an inlet to said fan extending upwardly therefrom, a tubular conduit extending upwardly from said inlet, an elbow secured to the top of said tubular conduit, a horizontally extending tubular conduit extending laterally from said elbow, said laterally extending tubular conduit extending toward the inspection door of the furnace, a second elbow at the end of said laterally extending tubular conduit, a valve housing secured to said elbow, said valve housing having an open end therein, said valve mean mounted in said open end, said valve means operable to open when said fan is in operation and to close when said fan is not in operation.

JONAS E. THORNQUIST.

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