US3111978A - Dual blower and burner for furnaces - Google Patents

Description

Nov. 26, 1963 G. PEOPLES 3,111,978

- ,DUAL BLOWER AND BURNER FOR FURNACES Original Filed Mairch 7, 1960 a Sheets-Sheet 1 ATTORNEYS Nov. 26, 1963 s. PEOPLES DUAL BLOWER AND BURNER FOR FURNACES Original Filed March '7, 1960 3 Sheets-She 2 Br ATTORNEYS.

G. PEOPLES DUAL BLOWER AND; BURNER FOR FURNACES Original Filed larch 7, 1960 Nov. 26, 1963 3 Sheets-Sheet 5 5294 124 7mm 2M ATTORNEYS.

United States Patent Ofiice 3,1 l 1,978 Patented Nov. 26, 1963 DUAL ELGWER AND BURNER FOR FURNACES Graydon Peoples, Marshalltown, Iowa, assignor to Lennon industries, the, Marshalltown, Iowa, a corporation of Iowa Original application Mar. 7, 1960, Ser. No. 13,245. Divided and this application June 19, 1961, Ser. No. 118,07 4

3 Claims. (Cl. 1581) This invention relates to a furnace construction having a dual blower and burner, the present application being a division of my copending application Serial No. 13,245, filed March 7, 1960.

One object of the invention is to provide a combination induced draft and combustion air blower comprising two blower wheels mounted on a single shaft and belt-driven by a single motor so that cost and maintenance are reduced, such motor serving also to operate the fuel oil pump when burning oil, thus securing extra economy and quietness of operation with fewer moving parts to service, and providing an interlocked safety feature as, if one blower wheel fails, the entire burner will shut down.

Another object is to provide the axes of a burner, heat exchangers, and a pump of the furnace construction, as well as the combination induced draft and combustion air blower, all parallel to each other, thus permitting integral mounting of the burner Without bearing strain and regardless of the type of installation or orientation of the furnace construction, the burner being so designed that it can be mounted upright, inverted or horizontal, as space permits.

With these and other objects in view, my invention consists in the construction, arrangement and combination of the various parts of my dual blower and burner whereby the objects above contemplated are attained, as hereinafter more fully set forth, pointed out in my appended claims and illustrated in detail on the accompanying drawings, wherein:

FIG. 1 is a perspective View of a dual fuel furnace construction embodying my invention, parts thereof being broken away to show internal details;

FIG. 2 is a front elevation of a combination combustion blower, induced draft blower and burner housing showing the combustion and draft scrolls therein;

FIG. 3 is a rear View of a combustion air damper and control box therefor;

FIG. 4 is a side elevation of the housing shown in FIG. 2 looking from the right-hand side of FIG. 2, and

FIG. 5 is a plan view of the housing shown in FIG. 2 looking from the top of FIG. 2,

On the accompanying drawings I have used the reference numeral 20 to indicate in general a housing for my furnace construction. An acoustically lined front door 22 is provided at one end thereof, spaced inwardly from which is a double-walled partition 24. The space between the door 22 and the partition 24 constitutes a burner vestibule in which all controls are hidden from sight, thus eliminating accidental bumping thereof and tampering therewith.

Inward of the partition 24 I provide a stainless steel tubular primary heat exchanger 26 having a front wall 28 terminating in a burner receiving tube 30. The rear end of the heat exchanger 26 is provided with an expansion joint comprising a front plate 34 and a rear plate 36 connected by thimbles 38 and 44) to a rear wall 32 of the heat exchanger and a rear flue box 42 respectively. The peripheries of the plates 3 and 35 are riveted or otherwise suitably secured together and the plates are spaced so that the spacing between them may decrease as the heat exchanger expands and increase as it contracts, thus producing a breathing action without straining the metal and thereby eliminating metal fatigue. This is a desirable feature under changing temperature conditions as it eliminates undesirable fracturing of joints or metal walls of the heat exchanger and associated parts.

The rear flue box 42 has a plurality of flues 4- communicating therewith and extending forward to communicate in turn with a front flue box 46. Each flue 44 has a corrugated bafile 45 therein and the fines constitute a secondary heat exchanger. The partition 24 constitutes a front wall for the flue box 46 and has an opening 48 therein (see FIG. 4) through which the products of combustion from the primary exchanger 26 and the flues 44 flow as will hereinafter appear. To hold heat losses in the housing 20 to a minimum, a corrugated metal radiation shield 100 (see FIG. 1) is provided, separated from the rear wall of the housing 20 by an air space 162.

A combination induced draft and combustion air blower housing 50 is provided, and shown in detail in FIGS. 2, 3, 4 and 5. The housing Stl has a rear wall 52 and a front wall 54. The rear wall 52 is positioned against the partition 24 and has a thimble 56 entering the opening 4-8 thereof. The front wall 54 is provided with an opening 159 (see FIG. 2) normally closed by a cover plate 152 shown in FIG. 3 wherein the inner face of the cover plate is illustrated. A damper blade 154 is supported by a shaft 156 oscillatably supported on the plate 12. A rotary solenoid or the like 158 when energized moves the damper blade 14 to a choke position such as illustrated by dotted lines in FIG. 2 and by solid lines in FIG. 3 during the ignition of an oil fire, but opens to a pie-adjusted position as a result of de-energizaton of the solenoid once ignition has been established. When operating on on-off gas alone, or in combination with on-off oil as a stand-by fuel, a manual fixed damper is used rather than an automatic damper.

A partition 58 divides the housing 56 into an induced draft blower section containing an induced draft blower wheel 60 and a combustion air blower section containing a combustion air blower wheel 62 as shown in FIG. 1. The induced draft blower section has a discharge opening 64 commmunicating with a flue outlet section 66 of the housing 50. The line section 66 has a top flue opening es and a side flue opening 70, as shown in FIGS. 4 and 5. In FIG. 1 the opening '79 is covered by a flue opening cover plate 72, and a flue extension 74 is shown associated with the top flue opening 68.

Associated with the blower wheel is a blower scroll 7 6 for directing the products of combustion from the blower Wheel into the flue outlet section 66. A damper 78 is mounted in the section 66 and adjustable by means of a control lever 80*. A dial 82 indicates the degree of opening of the damper 78 (it being shown completely shut in FIG. 2) and after the control lever 84 is adjusted, a wing nut 84- serves to retain the adjustment.

The combustion air blower wheel "62 receives air from the burner vestibule through an opening an in the front wall 54 of the housing 50, and discharges it into the lower part of the housing as directed by a second scroll 33 shown in FIG. 2 to enter the burner unit as will hereinafter appear.

Both blower wheels 66 and 62 are mounted on the same blower shaft 96 supported by a bearing assembly 92 which in turn is supported on the front wall 54 by three supporting vane-like brackets 94 as shown in FIG. 1. The shaft '90 is driven by a V-belt 96 from a motor 98 whereby both blower wheels 6% and 62 are driven by the same motor. By mounting both blower wheels 60 and 62 on a single shaft and driving them from a single motor, both manufacturing costs and maintenance are reduced to effect extra economy, and fewer parts are involved to service. This arrangement also contributes to quietness of operation. By having the blower wheels on opposite sides of the partition 53 which is heated by the products of combustion (usually about 600 F.) fiowing past it from the discharge opening 64 to the fine outlet section 65, all combustion air is preheated for maximum efiiciency of operation of the burner. The bearing assembly 92 is isolated from the hot blower wheel 60 by the cooler blower wheel 62 and the partition 53, and since the bearing assembly is located in the inlet opening 85 where room air at about 70 is fiowing into the blower wheel 62, the bearing assembly runs relatively cool because of room air being constantly drawn thereover, yet both blowers can be regulated separately to obtain the most efiicient combustion and provide the correct draft for particular installations by providing separate dampers for each (78 for the prodnets of combustion and another damper to be described later for the combustion air).

Both blower wheels are also simutlaneously operable during pre-purgc and post-purge periods to provide rapid purge of the combustion chamber by blowing room air into its intake end and withdrawing gases from its discharge end. It will be noted that the burner axis and the axes for the blowers and their motor are all parallel to each other so that the entire furnace construction can bev installed upright as shown, on its side (horizontal), or inverted and suspended from the ceiling if desired to suit a variety of different installations and fit various available space shapes.

The furnace housing 20 may be mounted on a blower housing shown generally at 104 having discharge openings 106 for air as indicated by arrows in FIG. 1 to circulate around the primary and secondary heat exchangers 26 and 44. This air then fiows into the top of the housing 20 which serves as a plenum chamber for heated air discharge outlets 168 provided with adjustable deflector blades 110 so that the heated air is properly directed throughout the area to be heated as desired for comfortable temperatures at working levels. Alternatively, duct distribution systems can be associated with the outlets 108.

The blower housing 104 has a pair of blowers 172 mounted therein. The blower wheels 173 of the blowers 172 are mounted on a single shaft 175 and driven by a belt 174 from a motor 176. Grills 1-78 permit entrance of air into the blower housing .1 34 to be forced by the blowers around the heat exchangers 26 and 44 and through the plenum chamber thereabove to the discharge outlets 108.

Describing next the burner unit indicated generally as B, a draft tube 114 is provided to serve as a support for a cylinder-shaped refractory 1 18. It will be understood that any suitable material, such as stainless steel, may be used in place of a refractory. The draft tube 114 is located in the burner receiving tube 39 of the primary heat exchanger 26 and receives combustion air from the scroll 88. A nozzle and igniter assembly is shown comprising a fuel oil atomizing nozzle mounted in a support 126, a fuel oil pipe 136 extending from the support 126 and a pair of high tension insulators 132 supporting spark electrodes 134 for the ignition of oil. It is contemplated that multiple fuel oil nozzles may be used where it is desirable to perform staged starting and multiple selection rates.

The burner B is so designed as disclosed in my parent application that either oil or gas may be burned, or both oil and gas may be burned. With both gas and oil fuels incorporated in a single burne unit, the cost of an extra burner when changing fuels is eliminated and the burner is available if desired for either straight gas or oil, instead of a combination of the two. The gas and oil are introduced at two separate points in the same firing assembly so that one burner does not have to compromise with the other in efficiency. Combustion of both fuels is very rapid and is substantially completed within the refractory 118, and fully completed within the stainless steel primary heat exchanger 26. It is unnecessary to change or reset combustion air or draft when direct spark ignited oil is used as the solenoid 158 for operating the damper 15-, may be connected into the control circuit in such a way that it is energized during the trial-for-ignition period, acting in effect as an air choke, and de-energized immediately following that period, thereupon automatically opening the damper 154 to the pre-set position during normal operation of the burner to provide optimum air for efiicient oil combustion. When the damper 154 is used for high-low-otf or two-stage gas-fired operation, the solenoid 158 may be connected into the control circuit in such a way that it is energized to place the damper 154 in the minimum combustion air position for low fire or reduced gas input, and de-energized to place the damper in prose openposition for high fire or maximum gas input.

When fuel oil is being burned, a fuel oil pump 1&0 (see FIG. 1) is provided and driven by a belt 162 from the blower shaft and supplies oil to the burner through the pipe 139. When only gas is being burned the fuel oil pump can be omitted and thus the dealer has a means to readily convert the basic furnace construction to oil heat, gas heat, or a combination of the two before it is sent out for installation.

The burner vestibule may have the various furnace controls such as 164 and 166 mounted therein, as well as the solenoid 158 as shown in FIG. 1. An access and inspeotion door 168 for the burner is also located therein normally covering an opening 17 0 in the front wall 54 of the housing 50.

Some changes may be made in the construction and arrangement of the parts of my dual blower and burner without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims any modified forms of structure or use of mechanical equivalents which may reasonably be included within their scope.

I claim as my invention:

1. In a furnace construction of the character disclosed, a wall, a combustion chamber extending from one side thereof, a burner on the other side of said wall discharging at one end into said combustion chamber and having a combustion air inlet at its other end, a combination induced draft and combustion air blower for said burner comprising a housing on said other side of said wall having a combustion air inlet opposite said wall and a pair of blower wheels therein, a partition separating one blower wheel from the other and dividing said housing into a first section contiguous to said wall and a second section spaced from said wall, passageway means for the products of combustion from the far end of said combustion chamber and returning to the inlet of said first section, said first section having arr-outlet adapted to discharge to a stack, said housing extending along said wall to encompass said burner and communicating said second section with the combustion air inlet of said burner, the outer wall of said housing being spaced from said combustion air inlet to permit combustion air from said second section to flow into said combustion air inlet, a single shaft on which both of said blower wheels are mounted, and a single outboard bearing for said shaft located adjacent said inlet of said second section and thereby in the path of combustion air flow into said inlet of said second section.

2. A furnace construction in accordance with claim 1 wherein said passageway means compress a flue box receiving the products of combustion from said combustion chamber, a second flue box, fines extending from said first flue box to said second flue box, a flue outlet receiving the products of combustion from said second flue box, said inlet of said first section communicating with said flue outlet.

3. A furnace construction in accordance with claim 1 wherein means is provided for supporting said beat-ring comprising vane-like supporting brackets located in the 10 path of the combustion air as it enters said inlet whereby they act as heat radiating fins to reduce the heat transmitted from said housing to said bearing.

References Cited in the file of this patent UNITED STATES PATENTS 750,590 Burpee Ian. 26, 1904 871,541 Wallace Nov. 19, 1907 2,172,667 Nelson Sept. 12, 1939 3,028,854- Reiily Apr. 10, 1962 3,033,269 Craig et 21.1 May 8, 1962

Claims (1)

1. IN A FURNACE CONSTRUCTION OF THE CHARACTER DISCLOSED, A WALL, A COMBUSTION CHAMBER EXTENDING FROM ONE SIDE THEREOF, A BURNER ON THE OTHER SIDE OF SAID WALL DISCHARGING AT ONE END INTO SAID COMBUSTION CHAMBER AND HAVING A COMBUSTION AIR INLET AT ITS OTHER END, A COMBINATION INDUCED DRAFT AND COMBUSTION AIR BLOWER FOR SAID BURNER COMPRISING A HOUSING ON SAID OTHER SIDE OF SAID WALL HAVING A COMBUSTION AIR INLET OPPOSITE SAID WALL AND A PAIR OF BLOWER WHEELS THEREIN, A PARTITION SEPARATING ONE BLOWER WHEEL FROM THE OTHER AND DIVIDING SAID HOUSING INTO A FIRST SECTION CONTIGUOUS TO SAID WALL AND A SECOND SECTION SPACED FROM SAID WALL, PASSAGEWAY MEANS FOR THE PRODUCTS OF COMBUSTION FROM THE FAR END OF SAID COMBUSTION CHAMBER AND RETURNING TO THE INLET OF SAID FIRST SECTION, SAID FIRST SECTION HAVING AN OUTLET ADAPTED TO DISCHARGE TO A STACK, SAID HOUSING EXTENDING ALONG SAID WALL TO ENCOMPASS SAID BURNER AND COMMUNICATING SAID SECOND SECTION WITH THE COMBUSTION AIR INLET OF SAID BURNER, THE OUTER WALL OF SAID HOUSING BEING SPACED FROM SAID COMBUSTION AIR INLET TO PERMIT COMBUSTION AIR FROM SAID SECOND SECTION TO FLOW INTO SAID COMBUSTION AIR INLET, A SINGLE SHAFT ON WHICH BOTH OF SAID BLOWER WHEELS ARE MOUNTED, AND A SINGLE OUTBOARD BEARING FOR SAID SHAFT LOCATED ADJACENT SAID INLET OF SAID SECOND SECTION AND THEREBY IN THE PATH OF COMBUSTION AIR FLOW INTO SAID INLET OF SAID SECOND SECTION.

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