US3667894A - Oil burner - Google Patents

Abstract

A GUN TYPE OIL BURNER PROVIDED WITH A BAFFLE PLATE BETWEEN THE BLOWER AND AIR INLET, COMBINED WITH SOUND DEADENING MATERIAL SO ARRANGED AS TO MATERIALLY LESSEN THE FAN NOISE.

Description

June 6, 1972 N. E. FLOURNOY 7,

011. BURNER Filed Dec. 7, 1970 2 Sheets-Sheet 1 FIG. l

June 6, 1972 N. E. FLOURNOY 3,

on. BURNER Filed Dec. 7, 1970 2 Sheets-Sheet 2 United States Patent 3,667,894 OIL BURNER Norman E. Flournoy, Richmond, Va., assignor to Texaco Inc., New York, N.Y. Filed Dec. 7, 1970, Ser. No. 95,651 Int. Cl. F23d 11/00 US. Cl. 431-114 4 Claims ABSTRACT OF THE DISCLOSURE A gun type oil burner provided with a bafile plate between the blower and air inlet, combined with sound deadening material so arranged as to materially lessen the fan noise.

The present invention relates to a gun-type oil burner and particularly to the suppression of fan noise in a burner employing a rotary or squirrel cage type pump or fan.

In the conventional gun-type, household oil burner, for example, the noise of operation has always been a matter of concern although the relatively low pressures conventionally employed can permit use of relatively low power drive motors of relatively low rotational drive speed.

Where, however, the speed and power of the motor is increased, the propensity toward operating noise likewise can become objectionable. This is particularly true in the case of gun type burners which operate at relatively high plenum pressures as referred to, for example, in copending applications, Ser. Nos. 78,069, 739,469, now Pat. No. 3,549,122, and Ser. No. 104,043. It has been found desirable, in such equipment, to operate with a barrier plate in the blast tube, provided with orifices such that a substantial pressure upstream of the barrier plate is employed to support high velocity and high kinetic jets or streams of air thru the orifices and in the vicinity of the burner tip.

This means, of course, that the rotary pump or sqirrel cage fan must necessarily operate to maintain a substantially higher pressure but with no greater actual flow rate than the conventional burner for which it is a substitute. This accordingly means additional air slippage or what is sometimes euphemistically known as stalling of the rotary squirrel cage type of pump which may be likened to a form of free wheeling in which the blower rotates at higher speed to maintain pressure but without producing corresponding flow. Under these conditions the blade tips pass at high speed thru a gas under pressure which is not flowing as it would if the pressure were lower. This produces a blade tip effect involving a turbulence such that the noise-making tendency is substantially incerased.

It is therefore a purpose of the present invention to obviate the foregoing difiiculty by, in large measure, effecting a diversion and deadening of the sound waves in a simple and effective manner. This is accomplished by a restrictive barrier which cuts ofi. a portion of the inlet chamber from communication with the air pump, diverting the sound waves from the fan blades to the opposite half of the chamber and specifically toward the inner wall thereof. This half is, in turn, provided peripherally with a sound absorptive material which absorbs the impinging sound waves such that the ultimate release of sound is unobjectionable.

One preferred, illustrative form of the present invention is shown by way of example in the present drawing wherein FIG. 1 is an elevational view of an oil burner embodying the present invention as viewed from the tip end of the blast tube; FIG. 2 is a side elevation taken on the line 22 of FIG. 1, with the air inlet chamber shown in vertical section; FIG. 3 is a smiilar sectional plan view of the burner taken on the line 33 of FIG. 2.

Referring now to the present embodiment, the burner comprises a conventional blast tube 10 provided with a frusto conical tip 12 and a plenum chamber 14. A squirrel cage type fan shown in FIG. 3, as at 16, is located in the plenum chamber 14 and driven by motor 18 via shaft 17. Liquid fuel oil passes to an atomizing spray nozzle, not shown, in the tip of the blast tube via oil pump 20 and conduit 22. The electrical controls are housed in container 24.

The present invention is concerned primarily with controlling the noise originating in the rotary pump, namely the squirrel cage blower 16. This, as is more specifically shown in FIGS. 2 and 3, comprises a cylindrical, open sided wheel having a series of peripherally arranged vanes 26, all extending axially and being formed in essentially the same circumferential and radial directions to direct air outwardly into the plenum chamber as the wheel is rotated. The squirrel cage wheel also comprises radial spokes or spiders 28 and hub 30 which, in turn, is driven by shaft 17 from motor 18 as aforesaid. Also, in the conventional manner a cylindrical air inlet chamber 34 is mounted on the side of the plenum chamber coaxial with the squirrel cage rotary fan 16 and open on its adjacent side so as to communicate with the interior of the squirrel cage.

The outer cylindrical surface of the inlet air chamber 34 is likewise apertured or opened and provided with an air band 36 which is similarly apertured or provided with a number of slots 38 so that by rotating the band 36 with respect to the cylindrical surface of the air chamber 34, the effective opening of the apertures and thus the air inlet may be varied at will. The band 36 is, in turn, tightened or loosened on the inner chamber by means of fastener 40.

Referring now more specifically to the details of the present invention, sound control is primarily effected by an intake air silencer comprising a flat, semi-circular plate 42; see FIGS. 2 and 3.

Plate 42 is, as shown, provided with a circumferential, semi-circular margin 44, such that it covers one-half of the axial opening 43 in the end of the inlet air chamher as shown in FIG. 1; moreover, being semi-circular in shape and recessed at 46 to accommodate the driving shaft 17. The plate 42 is held in place by a lower laterally extending flange or tab 48 attached to an abutting projection 49 on the chamber or housing 34 by fastener 50. Preferably, as is shown, the plate 42 is formed out of relatively heavy material to avoid vibration and fits snugly against the inner flange of housing 34 as shown in FIG. 1. Also, it may and preferably is formed of suitable sound-deadening material of the type represented by lead, tin or the like. On the other hand, where economy dominates, a mild steel or preferably an aluminum plate will do.

In any event, the member 42 at least performs the function of sealing oif and diverting at least one-half of the sound which otherwise would emanate thru the circular passageway between the plenum and the inlet air chamber. Furthermore, the diversion of the sound waves is in a direction indicated more or less diagrammatically by the arrows in FIG. 3, namely toward the peripheral inner surface of the cylindrical inlet chamber and specifically along the segment opposite the semi-circular plate 42.

In the interest of clarity it is to be particularly noted that the arrows as shown in FIG. 3 are not intended to represent flow of air or any other fluid which, in actual fact, flows in the opposite direction. On the contrary, these arrows specifically show and represent the path of the sound waves in passing from the burner.

To absorb the nascent sound waves now impinging directly on the right hand half of the inner portion of the inlet chamber as viewed in FIGS. 2 and 3, this surface is provided with a sound deadening material represented as at 52 in FIGS. 2 and 3.

The class of sound deadening material has been broad- 1y treated in many fields including some considerably remote from the present one. Since considerations which contribute to success in the absorption of sound are well known, these will not be extensively covered here other than to say that such materials are usually composed of relatively soft materials. Accordingly, the present invention contemplates the use of such sheet materials in the position indicated by reference numeral 52.

A preferred material which has been found suitable for the present purpose is a corrugated asbestos board composed of relatively soft asbestos fibres arranged in typical corrugated form with one fiat sheet supporting a corrugated sheet such that the thickness approximates in the neighborhood of A3" to ii The flat sheet of the board is provided with a layer of aluminum foil and the corrugated interior sheet of material is readily amenable to curvature to precisely fit the interior annular surface of the air inlet chamber and more specifically, the fiat, foil-covered surface can be bent to fit the interior surface of the air inlet chamber with the corrugated layer interiorly thereof and is preferably cemented thereon with Scotch Grip or some other commercial insulating adhesive. Moreover, the radially internal corrugations, while permitting curvature of the corrugated board as previously indicated, tend by virtue of the curvature to be brought closer together which is believed to yet further involute the interior interstices and thus the sound absorptive and sound deadening qualities of the absorbent are improved.

The general arrangement of the corrugated asbestos board 52 is indicated in FIG. 2 wherein the corrugated portion of the board is shown in section on the interior surface thereof, with the parallel corrugations and the radially interior face being shown more clearly in FIG. 3.

Also, as previously intimated, the layer of sound absorptive material 52 covers circumferentially the entire cylindrical portion of the interior surface of the inlet chamber which is not cut off or overlaid by the semicircular plate 42.

Therefore, as indicated in FIG. 3, the objectionable sound generated by the high speed passage of the squirrel cage fan blades thru the high pressure area passes outwardly, as shown by arrows 56, meeting the barrier plate 42 which diverts them to the right as shown in FIG. 3 into direct impingement with the absorptive board 52. Such of the reflections as are not completely absorbed, shown by the dotted line arrows 58 continue outwardly thru the openings in the housing 34 and thru the peripheral band 36.

Irrespective of the functional explanation of the effect and the question of to what extent sound is absorbed or diverted by indirection, the fact remains that the noise abatement is so apparent that it is quite apparent to any ordinary observer without resorting to comprehensive technical noise measurements.

I claim:

1. In a gun type oil burner having a blast tube supplied with air under pressure from a plenum chamber by a squirrel cage type blower which is supplied with air from an annular, air-inlet chamber arranged coaxially with respect to said squirrel cage blower fan and having a circular lateral side opening opposite the side of such squirrel cage fan for supplying air axially to the interior thereof, means for deadening the objectionable sound produced by the operation of said fan comprising,

an essentially semi-circular plate covering approximately one-half of the opening between said air inlet chamber and said squirrel cage fan, thereby to divert sound produced by said fan into the semi-circular section of said air inlet chamber opposite the uncovered half of said opening and toward the inner periphery of said annular air inlet chamber, and

a sound absorptive deadening layer of material occupying the annular inner surface of said air inlet chamber thruout the semi-cylindrical wall section thereof opposite the uncovered half of said opening whereby said diverted sound impinges said sound deadening layer before passing from said chamber.

2. A gun type oil burner as defined in claim 1 wherein said sound deadening material comprises a layer of corrugated sound absorptive material.

3. A gun type oil burner as defined in claim 1 wherein said sound deadening material comprises a layer of corrugated sound absorptive material comprising a flat layer of sound absorptive material cemented to the interior of said air inlet chamber,

and a corrugated layer of sound absorptive material fastened to said first layer with the corrugations facin'g inwardly.

4. A gun type oil burner as defined in claim 3 wherein said sound deadening material comprises relatively soft asbestos with the corrugations on the interior surface thereof and extending axially of said chamber.

EDWARD G. FAVORS, Primary Examiner

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