US2111818A - Rotary bladed structure - Google Patents

Description

R. M. SHERMAN ET AL 2,111,818

ROTARY BLADED STRUCTURE Original Filed Jan. 27, 1937 5 Sheets- Sheet l March 22, 193s.

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ROTARY BLADED STRUCTURE Original Filed Jan. 27, 1957 3 Sheets-Sheet 2 .ras es RaZZs Elow/M 5271@ waan s707132, 0a??Z2?e?' March '22, v1938. R. M. SHERMAN ET Al. 2,111,818

ROTARY BLADED STRUCTURE original Filed Jan. 27, 1957 s sheets-sheet z @i Willms-'- Patented Mar. 22, 1938 ROTARY BLADED STRUCTURE Rsllston M. Sherman, Glastonbury, and John Carlberg, West Hartford, Conn., assignors to The Silent Glow Oil Burner Corporation, Hartford, Conn.. a corporation of Connecticut Original application January 27, 1937, Serial Divided and this application April 23, 1937, Serial No. 138,604

Claims.

This invention relates to rotary bladed structures usable for impelling a body of air with the accompaniment of either pressure or suction, and more particularly, though not exclusively, to the utilization of such structures for the purpose of supplyingair in the burning of liquid fuel, herein referred to for descriptive purposes as oil.

This is a division of our application, Serial No. 122,650, led January 27, 1937.

In the drawings:-

Fig. 1 is a. side elevation oi' a burner of the socalled gun type, partly broken away to show the relation of the rotary bladed air impeller therein;

Fig. 2 is a partial plan in section, showing the casing of the burner of Fig. 1 with the air impeller therein, the blades of the latter beingvshown in closed position to cut oli the air;

Fig. 3 is a similar view, showing the impeller with the blades open in the positions to which they move under centrifugal force to force an air supply to the burner when the impeller is rotated;

Fig. 4 is a front view of the impeller with the blades closed; and

Fig. 5 is a similar view showing the blades open.

Referring to the drawings and to one Aembodiment of the invention herewith submitted, this is shown for illustrative purposes (Figs. 1, 2, and 3) as embodied in an oil burner of the gun type. This is provided with a casing, the upper part ii of which is generally cylindrical in form and the lower part I3 of which merges into a prolonged straight cylindrical tubular air discharge conduit member i5 having itself or in an extension thereof an open mouth at its discharge end, the conduit being arranged in a generally tangential relation to the lower or discharge part of the casing.

Within the casing is a rotary air impeller (hereinafter more fully described) mounted on and driven by the shaft i1 (Figs. 2 and 3) of an electric motor i9, which4 latter is arranged on a supporting plate at one side of the casing. The impeller on its opposite side is connected by the resilient driving 'connection 2i to the prolonged end of the driving shaft 23'01 the oil pump 25 mounted on a shelf or extension at the outside of the casing and at the opposite side thereof from the motor.

The side wall of the casing adjacent the motor is closed except for the opening through which the driving shaft Il extends, while the opposite side Wall facing the pump 25 is provided with a circular admission opening 2l of substantial size and coaxial with the impeller shaft. The volume of air admitted through the air admission opening may be controlled by a disk-shaped shutter 29 (Figs. 2 and 3) slightly larger in diameter than that of the opening 2l, the shutter being adjustable toward and away from the opening and mounted on a sleeve il surrounding the pump 25 on which it may be held iixed by any suitable means, such as the set screw 33.

The impeller, which rotates in the direction of the arrow shown in Figs. 1 and 5, is mounted in eccentric relation to the inner peripheral walls of the casing so that the clearance between such walls and the blades of the impeller, when the blades are fully opened to the position shown in Figs. 1, 3, and 5, is at a minimum at the point designated 55 in Fig. 5 (which may be termed the point of air registry or cut-off), but gradually increases from that point to the air discharge portion at the bottom thereof.

Positioned axially within the casing i5 is an oil delivery pipe 3l terminating just short of the conduit mouth in a nozzle 39 and connected to an oil supply pipe di. Oil is drawn by the pump 25 from a suitable source of supply (not shown), such as a main storage tank, through the pipe i3 and strainer it and delivered to the supply pipe tl and nozzle 39 through the pressure reducing valve tl' at a relatively high pressure to produce a mechanical atomization of the oil leaving the nozzle and to discharge from the latter a, coneshaped oil spray without premixture with air. The oil spray, commingled with air discharged through the conduit i5, is ignited in front of the nozzle by sparking electrodes (not shown).

For convenience in assemblage or inspection of the interior working parts of the burner, the impeller housing is formed of two separable and interfitting parts, one of which comprises the lower half i3 of the casing and the lower half of the immediately adjacent portion of the tubular air conduit i5. The other part comprises the upper. half I i of the casing and the upper half oi' the tubular conduit portion. The upper part has a bead or flange t9 which laps over the edges 5l of the lower part so that the two sections are in. intertting relation, being fastened together by means, such as the screws 53 (Fig. l), permitting the removal of the upper part and the exposure of the impeller and other interior parts for purposes of repair or inspection.

In the illustrated form of the burner, the air conduit is completed by a cylindrical open mouth or extension 55 which tlts within the ends of the conduit section formed by thel two separable parts of the casing and is removably secured to the lower half of that section by the provision of flanged walls El bolted to the corresponding flanged walls 58 at theend of such lower section. 'I'he housing is supported by any suitable means, such as the posts 60 resting on the floor. The conduit extension discharges air about the nozzle into a combustion chamber through the walls 69 thereof, being preferably the only source of any substantial amount of air entering the chamber.

Referring now to the air impeller, shown in detail in Figs. 2, 3, 4, and 5, this comprises a series of similar light, sheet-metal, concave-convex segl mental blades 6i, herein eight in number, each slightly convex on its air delivery face and with an arc-shaped outer edge. the blades being so assembled that when they are closed, as in Figs. l and 4, the convex faces of the blades present an outer conical surface, with the outer edges of the blades at the base of the cone forming a substantially unbroken peripheral edge.

Each blade at the inner end of one of its edges has a small inturned flange Gli, and on the same edge nearer its outer end a similar flange B5, both bent at right angles inwardly from the convex sides of the blades, by means of which the blade is pivotally mounted for turning movement on a pin or small rod 61 and on which it is held by the small disk-shaped washer 69 secured on the end of the pin. The several rods t1 are xedly secured in equally spaced relation to and about the conical walls of the ian hub ll and extend outwardly therefrom but are inclined to the axis of rotation of the hub. The inner edges of the blades have a concaved, arcuate shape so that, when the blades are closed (Figs. 2 and 4), they t about the periphery of the hub 1l and provide 'a closure for the small end of the structure which assumes the form of a truncated cone.

The ian hub has a sleeve extension 13 by which it is mounted on and secured to the motor shaft il by a set screw or other means, as indicated in Figs. 2 and 3. A torsion spring 'it encircles each pin, having one end fastened to the pin and the other extending over and lying against the adjacent edge of the blade, so that, when the fan is normally at rest, the blades are urged by the light pressure of the spring in a direction moving them to the closed position shown in Figs. 2 and 4. In this position the free end of the concave face of each blade comes to rest and in overlapping relation to the convex face of the next adjacent blade near the pivoted edge thereof.

The impeller blades are of such dimensions that in closed position the continuous peripheral edge of the cone formed by the outer arc-shaped edges overlaps the periphery of the air admission opening 21 and the closed blades form a truncated cone, providing a substantially complete closure for such opening and preventing the entrance of any substantial amount of air therethrough. The sleeve extension 13 is preferably positioned on the motor shaft so as to bring the edges of the closed blades almost, but not quite, in contact with the walls of the casing surrounding the opening 21, sufilcient clearance only being left to permit the blades to move without friction against the casing when rotation of the impeller is started.

When the impeller is started into rotation, however, the angle of inclination of the pivotal axes of the blades causes the latter to move under centrifugal force about the pivot points and open up against the opposing pressure of the spring v15, This opening movement continues until either positively arrested or until the center of gravity of each blade reaches its maximum radial distance from the axis of rotation.

It will be observed that the rods 61 terminate short of the outer arc-shaped edges of the blades by an appreciable distance so that they lie entirely within the conical formation of the structure when closed, as indicated in Fig. 2. The corner of each blade beyond the outer flange is out away, as best indicated in Fig. 3, both as a convenience in manufacture and to bring the center of gravity of the blade nearer the free edge thereof, effecting a more forcible blade-opening movement, the overlapping of the free edge of the next adjacent blade being sumcient to cover the cut-away corner of the blade when the blades are closed. This overlap also provides a blade of greater width when the blade has opened under rotation of the impeller and provides a greater volume of air delivered to the burner.

It will be observed that the impeller is positioned in the housing on the delivery side of the air admission opening and the axis of rotation of each blade is inclined to the direction of the resulting movement of the air, so that, when opened by centrifugal force, the blades move away from the air admission opening 21 into the enlarged space of the housing and in the same direction as that of the resulting .movementv of the air, swinging about their inclined pivotal axes in the same direction as that in which the impeller is rotated.

When rotation ceases, the blades swing in a direction opposite to the preceding rotation of the impeller and move back in a direction opposite to that in which the air is drawn into the casing and into a position where the air admission opening is closed and further entrance of air prevented.

This relation of the impeller to the air admission opening and to the direction of air movement avoids the creation of a back pressure, and the resulting diminution of the eiciency o'f the impeller, which has been found to result from positioning the impeller von the inlet side of the air admission opening where, to render it at all effective, it should be enclosed circumferentially by Walls diverging away from the air admission opening to be sealed and providing a reasonable clearance only for the opening of the blades, which walls accentuate the back pressure referred to.

When the impeller is rotated, the blades swing outwardly, spreading transversely across the chamber within the casing and with their smooth convex faces presented in`impelling relation to the air. The rotation of the impeller blades drives the air around the casing and expels it forcibly in a generally tangential direction through the lower discharge portion of the casing into and through the tubular air conduit. Air is drawn into the casing through the air admission opening 21, and in a generally axial direction with relation to the impeller, by the suction created through the movement of the blades across the point of air registry 35, as well as by the slight inclination or curvature of the convex faces of the blades, which accelerates the normal movement of the air into and through the air opening.

A positive stop may be employed to adjustably limit this opening movement of the blades, but

as such adjustment tends to alter the velocityvolume ratio of the air impelled it is preferable to allow the blades to' open to a fixed working position and regulate the volume'of air by adjusting the air shutter or damper 29. As employed in the present case, where the rotary impeller is required to take the air in axially and deliver it in a generally tangential direction, the blades are preferably allowed to open to their maximum posinon, which is substantially as indicated m rigs. 3 and 5.

As soon as the rotation of the impeller ceases.

` caused, forexample, by the action of a room thermostat or other switch designed to stop the rotation of the motor and the functioning of the burner, the blades move back to the closed position indicated in Fig. 2, stopping further entrance o! the air into the casing and air conduit. This provides theiunction oi automatically stopping further passage of cold airI into the furnace as soon as the burner stops and as soon as the imponer ceases to iunction in creating its forced draft. This automatically seals od the furnace from the entrance ot cold air, whether induced by the natural` draft oi the chimney or otherwise, thereby protecting the walls oi the combustion ober and the furnace from the chiliing edect of such wld entering air and conserving the heat previously imparted to such walls.

Claims relating to the cooperative relationship between the features of the rotary bladed structure and those oi the liquid iuel burner are separately claimed in application, Serial No. 122,650,

I of which this is a division.

Claims generic to the structure herein disclosed are presented in application, Serial No. 84,694, died .lune lll, i936, by Sherman, Carlberg, and Nenn.

E.; e there is herein shown and described for purposes of illustration one specific embodiment of the invention. it is to be understood that extensive deviations and changes made be made in the iorm, relative ement and details of the herein shown and in the application of the subject matter of the claims, all without departing from the spirit of the invention.

We claim:

l. A walled structure having an orlce for the passage of air, and a rotatable air impeller for forcing air through the orifice, said impeller having movable blades mounted each to turn on an axis extending outwardly from the axis of impeller rotation but inclined to said latter axis in a direction opposite to that of the resulting air movement, said blades being movable under centrifugal force to move to an air impelling position and to present a smooth, unobstructed impelling lace to the air, but automatically movable on' the stoppage oi' the impeller to eilect a substantial closure oi' the air oriiice.

2. A rotatable air impeller having a series of blades mounted each on an axis extending outwardly from but inclined to the axis o! rotation of the lmpeller in a direction opposite to that of the resultant air movement and normally moved to a position that each blade is in such relation to the adjacent blade as to form a substantially closed conical structure, said blades being movable under centrifugal force about an axis to an air impelling position, the axis of each blade being oil-set at the side of the blade forming the inside ofthe conical structure and means for rotating said impeller.

3. A rotatable air impeller having a hub, a series ol' blades mounted each on a pivot pin extending outwardly from but inclined to the ams ol rotation oi the hub, each blade being adapted to swing about its pivot pin under centrifugal force to an air impelling position, the pivot pin of each blade being positioned near one edge of the blade on the side thereof opposite to `the direction in which it s under centrifugal force.

i. The combination with a structure having an air orice i'or the passage oi air, of a rotatable air impeller with? means for rotating the same, said impeller having a series oi concavo-convex blades mounted each on an axis at the concave side oi the blade near one edge thereof, said axis extending outwardly from but inclined to the axis of rotation in a direction opposite to that of the resultant air movement, said blades being normally moved'to an overlapping position to form a closed conical structure operatively related to said orifice. and said blades being each movable about its under centrifugal force when the impeller is rotated.

5. A rotatable air impeller having a hub, a series of blades mounted each on a pivot pin extendingoutwardly from but inclined to the axis oi' rotation of the hub in a direction oppo- 'site to that od the resultant air movement, each blade being adapted to swing about its pivot pin under centrifugal force to an air impelling position but normally moved to form-ea substantially blade. f'. i

RAILSTON M. uw' JOHN CARIBERG.

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