US2814430A

US2814430A - Air control gate for oil burner and the like

Info

Publication number: US2814430A
Application number: US373819A
Authority: US
Inventors: Reginald W Beckett
Original assignee: Individual
Current assignee: Individual
Priority date: 1953-08-12
Filing date: 1953-08-12
Publication date: 1957-11-26
Anticipated expiration: 1974-11-26

Description

Nov. 26, 1957 R. w. BECKETT AIR CONTROL GATE FOR OIL BURNER AND THE LIKE Filed Aug. 12, 1953 [N VEN TOR. PEG/Nam M BECKETT BY M/M A TTOQNE I United States Patent AIR CONTROL GATE FOR OIL BURNER AND THE LIKE Reginald W. Beckett, Elyria, Ohio Application August 12, 1953, Serial No. 373,819

11 Claims. (Cl. 230-114) This invention relates to fluid fuel burners and more particularly to regulation and control of the air supply in burners incorporating a power driven blower or fan.

It has long been recognized that proper control of the air supply in burners for oil and other fluid fuels is of prime importance in obtaining optimum efficiency and desirable operating characteristics. Oil burners and the like employing motor driven fans and blowers commonly include means such as gates, shutters and louvers for governing the air flow.

In practice, a single model or design of oil burner may be used to burn oil or other fluid fuel at many different rates so that the rate at which air is supplied to support combustion may vary over a relatively wide range. Since it is not feasible to supply completely different components for each burner model and since individual burners of the same model will vary as to air requirements because of nozzle differences and the like, the provision for air control to obtain different air supply rates without losing the fundamental characteristics of the flowing air with respect to rotation and turbulence is an ever present problem in burner design and construction. This problem was encountered in the development of the socalled plate mounted burner" of U. S. Patent 2,599,153 and of Serial No. 152,353, filed March 28, 1950, now Patent No. 2,777,509, and of United States application for patent, Serial No. 149,550, filed March 14, 1950, of which application the present application is a continuation in part. United States application, Serial No. 149,550 is in turn a continuation in part of application, Serial No. 766,967, filed August 7, 1947, now United States Patent 2,506,192, and of United States application, Serial No. 24,559, filed May 1, 1948, now the previously referred to United States Patent No. 2,599,153.

Burners of the character referred to comprise an open faced housing having a main wall carrying outside and partition walls which define fan scroll and air receiving chambers and a passage connecting the chambers for conducting air discharged tangentially from one chamber into the other. The open face of the housing is closed as by a suitable flat plate or as by being disposed against the upright wall of a heater. The closure plate or the heater wall is formed with openings registering with the housing chambers so that air may be drawn into the fan scroll chamber through one such opening. Because of the geometry of the burner housing, particularly because of its normally close-coupled relation to the heater structure with which it is normally associated but also because of the use of a separate plate for closing the open face of the housing, conventional air control devices and arrangements are not wholly satisfactory and do not provide the desired range of oil rates, the desired air flow characteristics or turbulence. The present invention seeks to provide an improved combination of burner housing and air control gate, the combination being particularly useful in fluid fuel burners comprising open face housings.

According to one of its principal features the combination is embodied in a burner housing having connected fan scroll and air receiving chambers and a movable control gate disposed in a connecting passage between the chambers, tne gate being so located as to intercept at least a portion or the air discharged tangentially into the passage from a mass of air rotating in the scroll chamber and to deflect such lntercepted air into the central portion of the air receiving chamber. As a refinement of this aspect of the invention the control gate is pivoted on the housing to swing from a retracted position in which it substantially parallels the path of air flowing tangentially from the scroll chamber and tangentially into the receiving chamber to an air intercepting and deflecting position, the gate being movable progressively across the flow path of the air so that air discharged tangentially from the periphery of the fan chamber is influenced by the gate to flow at a reduced rate and into a more central part of the receiving chamber. By this arrangement the normal tangential entrance of the air into the receiving chamber is reduced or varied as desired simultaneously with the reduction or variation in the flow rate.

In accordance with another aspect of the invention an air control gate is pivotally mounted to swing about an axis at or adjacent the outer periphery of the fan chamber and the gate is suitably notched or apertured in the provision of an opening which in all positions of adjustment of the control gate permits part of the outermost portion of the tangentially or peripherally discharged air to flow through the control gate and thereby maintain a predetermined minimum tangential flow of air into the receiving chamber, this being one of the objects of the invention.

Another aspect of the invention concerned with the piv otal mounting of an air control gate to swing across the tangential passage connecting fan scroll and air receiving chambers contemplates the provision in one of the walls, preferably the outer or tangential wall of the connecting passage, of a recess to accommodate the air gate pivot and the end of the gate so that the air gate at least at the pivoted end is recessed into the wall of the connecting passage in the provision of a streamlined air flow arrangement which avoids objectionable eddy currents and turbulences in the transfer of air from the fan scroll chamber to the air receiving chamber.

A still further feature and objective is concerned with the mounting of an air control gate in a burner housing of the open face type, the invention contemplating the use of a pin mounted in a boss on the main wall of the housing and projecting as a cantilever from such boss to receive an air gate for swinging movement. As a refinement of this aspect of the invention the pivot pin is journaled in the boss with the air gate secured on the pin so that turning of the pin, preferably by means secured on an externally projecting cantilever portion thereof, shifts the air gate to different positions of adjustment within the housing.

Other objects and advantages pertain to certain novel features of construction and combinations and arrangements of parts which contribute to the provision of a generally improved air control arrangement that is simple and inexpensive and can be readily assembled and adjusted. The features and objectives referred to and others not specifically mentioned above are apparent in the following detailed description of a preferred embodiment of the invention, this description being made in connection with the accompanying drawings forming a part of the specification.

In the drawings:

Figure l is an elevational view, partly in section and with parts broken away and removed, showing the hous ing of a plate mounted oil burner having an air control system embodying the principles of the present invention, the flat cover plate or closure being removed from the open face of the housing to show the interior of the housing and certain of the components of the burner used in association with the housing;

Figure 2 is a fragmentary side elevational view of Fig. I. this view showing the housing and related parts and components as though taken along the line indicated at 22 of Fig. 1 and enlarged with respect to that figure:

Figure 3 is a fragmentary enlarged detail showing the swingable air control gate and its location in the housing passage which connects the fan scroll chamber and the air receiving chamber of the burner;

Figure 4 is a fragmentary sectional detail through the housing showing the mounting means for the gate, this view being taken substantially along the line indicated at 44 of Fig. 3; and

Figure 5 is a fragmentary sectional detail through the boss formed on the main Wall of the housing for journaling the pivot shaft of the air control gate, this view being taken substantially along the line indicated at 55 of Fig. 4.

Burners for oil or other fluid fuels of the type for which the air control gate and system of the present invention is adapted may be either free standing or plate mounted as desired, a burner having convertible features making it suitable for both types of application being described in copending application Serial No. 152,353. Since the in vention is concerned with the control of air flow through the passage connecting the fan scroll chamber and the air receiving chamber of the housing, the present drawings are directed principally to the housing and the air gate in the housing. reference being made to the earlier patent application for more complete descriptions and illustrations oi the burner and the manner in which it is used.

Briefly described, the burner comprises an open face housing generally ovate in shape and including a substantially fiat main wall 1 on which related burner com ponents are mounted. Extending laterally from the main wall 1 and substantially normal to the plane of the latter are an arcuately or semicylindrically curved top wall 2 and arcuately curved lower side walls 3 and 4. Along opposite sides of the housing are upright walls 5 and 6 which connect the ends of the top wall 2 t the upper ends of the lower side walls 3 and 4, respectively. Like the curved walls 2, 3 and 4. the side walls and 6 are normal to the plane of the main wall 1, and, as shown. may be integral therewith. The interior of the housing is divided into a number of chambers or compartments by partitions that are normal to the plane of the main wall and, like thet outer or marginal Walls 26. may be integral with the main wall.

In the top of the housing an upper arcuately curved partition 7 defines a blower or fan chamber 8 and in the lower part of the housing an arcuately curved partition defines an air receiving chamber 10. The inner ends of the partitions 7 and 9 are connected by an upright partition 11 spaced from the curved lower side wall 3 and the upright straight side wall 5 to define a passage 12 which connects the upper fan chamber to the lower air receiving chamber. The upper end of the fan chamber partition 7 is curved into or joins tangentially with the curved top wall 2 of the housing to provide a relatively smooth continuous pe ripheral wall for the fan chamber 8 from a cutoff point 14 where the curved partition 7 joins the upright connecting partition 11 to a discharge point 15 at the entering end of a connecting passage 12. The partition 9 which defines the air receiving chamber II] is joined tangentially to the lower side wall 3 or, as shown, may comprise a smoothly curved continuation of the latter so that air may flow substantially tangentially from the connecting passage 12 into the receiving chamber 10 to rotate in the latter and form a spirally moving body which continuously advances axially from the receiving chamber into and through an air tube 16 which defines a passage that extends as a continua tion of the chamber.

In a heater-burner combination the burner is secured in spaced relation to upright wall 17 of the heater by a cantilever type mounting arrangement. The open face of the burner housing is covered by a closure plate 20 which constitutes a wall panel of the burner housing. This fiat plate is interposed between the housing and the base of the air tube 16, being formed with an opening 22 which registers with the air receiving chamber 10 in the housing and with the passage through the air tube. The closure plate is also formed with a circular aperture 21 concentric to the axis of a sirocco type blower or fan which is rotatably mounted in the fan chamber 8, the aperture 21 constituting the inlet through which air enters the fan chamber.

An electric motor 23 is flange mounted as by screws 24 against the main wall 1 of the housing, the motor having a shaft 25 which extends into the air chamber 8 through an opening 26 in the main wall I. The fan 19 is secured on the shaft 25 so as to be driven by the motor 23 and to thereby force air tangentially from the scroll chamber 3 through the connecting passage 12 and into the air rcceiving chamber 10. As shown in Fig. l, the fan E9 is eccen trically located with respect to the partition 7 and the top wall 2, the circular periphery of the fan being closest to the chamber defining walls at or adjacent the cutoff point 14. There is thus defined between the circular fan periphery and the walls 2 and 7 an arcuately curved chamber portion which progressively increases in cross sectional area in the direction of fan rotation (indicated by the arrow) substantially from the cutotf point 14 to the discharge point 15.

To locate and support the burner on the upright wall 17 of the heater, studs 28 are welded to spaced points of the outside face of the plate or wall 17, these studs having reduced diameter threaded portions receivable through openings in cars 29 formed on the burner housing. The closure plate 20 has openings that receive the studs 28, the shoulders provided by the large diameter portions of the studs bearing against the closure plate to hold the latter against the open face of the burner. Other screws (not shown) extend through the closure plate and into the burner housing to hold the closure plate in place.

Extending from the air receiving chamber 10 and into and through the air tube 16 is a fuel conduit and ignition electrode assembly which carries the fuel to the burner nozzle (not shown) and which energizes the electric ignition. This assembly includes a bracket 30 secured as by bolt 31 in the bottom of the partition wall 9 defining the air chamber 10. The bracket supports a tube 32, that leads to the nozzle, and insulated electrodes 33, that extend to an ignition point adjacent the nozzle. Energiza tion of the ignition electrodes is through or by means of a transformer 35 hinged to the housing wall 1 for swinging movement about a vertical axis across an opening 36 in such wall. The secondary of the transformer is connected to terminals 37 which make electrical connection with spring contacts on the electrodes 33 when the transformer is in closed position across the wall opening 36. The primary of the transformer is connected by an insulated two-wire cable 38 to the controls of the heating system, connection being made in a wiring box 40 comprising that part of the interior of the housing between the partitions and the side walls 4 and 6. The wiring connections to the electric motor 23 are also made in the wiring chamber 40, a two-wire cable 41 from the motor entering the chamber 40 through an aperture in the main wall 1 of the burner housing.

In the operation of the burner, rotation of the fan 19 produces a rotating mass of air in the fan chamber 8, this air discharging centrifugally from the fan chamber at the point 15 through the opening into the connecting passage 12. Replacement air enters the fan chamber through the central circular opening 21 along the rotational axis of the fan and moves radially outwardly through the blades of the fan into the tapering passage portion lying between the fan periphery and the Walls of the chamber 8, the fan and chamber thus constituting the conventional fan scroll arrangement.

At the bottom of the connecting passage 12 the curved portion 3 of the housing side wall deflects the air to enter the receiving chamber 10 tangentially so as to rotate in the latter in the same direction and substantially in the same plane as the mass of air rotates in the fan chamber 8. From the receiving chamber 10 the rotating air advances as a spiral column through the air tube 16, the air tube being a continuation of the receiving chamber 10. Oil or other fluid fuel is supplied to the spirally advancing air column at the end of the air tube 16 or at the end of an extension or head on such air tube and the resulting mixture is ignited to burn in accordance with well known principles.

Control of the flow of air from the fan chamber 8 through the connecting passage 12 and into the receiving chamber 10 is effected by a swingable gate 45 with which the present invention is concerned. This gate is made of sheet metal as by stamping and is suspended from a pivot pin 46 aflixed to the top edge of the gate for movement in an arc across the connecting chamber 12 from the full line position shown in Fig. l to the broken line position of that figure in which the lower end of the gate engages the connecting wall 11, the latter thus constituting a limiting stop for the gate. The upright side wall of the burner housing is offset laterally from the plane of tangency between the housing top curved wall 2 and the housing lower curved side wall 3 as by short connecting

walls

47 and 48 in the provision in the burner housing of a side recess 50 which opens into and is continuous with the connecting passage 12. The pivot pin 46 is located in the recess 50 so that in its full open position (full lines of Fig. 1) the gate 45 lies substantially in the plane of tangency between the curved wall portions 2 and 3 of the housing. The gate thus constitutes, in its full open position, a smooth surfaced tangential guide for air moving between the fan chamber 8 and the receiving chamber 10 so that a nonturbulent streamline flow may be obtained. In all positions to which it may be adjusted the air gate is wholly outside the air receiving chamber 10 in the lower part of the housing and does not interfere with the helical or spiral flow of air in such chamber.

The pivot pin 46 is a square sectioned bar having one end turned down in the provision of a circular sectioned rod portion 55 supported to turn in a bore drilled through an enlargement or boss 51 formed integrally with the main wall 1 of the housing and projecting from the plane of the wall into the recess 50. The boss 51 desirably fills the angle between the main wall 1 and the short connecting wall 47 and is integral with the latter and also with the upright side wall 5. The upper end portion of the gate is disposed flatwise against one of the flat sides of the pivot pin, the latter being supported by the boss 51 in cantilever fashion. The gate is suitably secured to the projecting cantilever portion of the pivot pin as by drive screws 52. It is feasible, of course, for the gate to swing freely on the pivot pin under control of a suitable actuator, but it is preferable, as shown, to employ the pivot pin as an actuator.

One corner of the rectangular plan form gate is relieved or cut away, as shown in Fig. 4, to provide a notch-like opening 54, the notch opening being larger than the boss 51 to permit a minimum flow of the air discharged tangentially from the outer periphery of the fan chamber 8 to by-pass the gate in all positions of the latter.

The circular sectioned rod portion 55 of the pivot pin projects through the housing wall 1 and is threaded to receive a nut 43 and an adjusting knob 60. A pointer arm 62 has an apertured hub portion received over the projecting portion of the pivot rod 55, the pointer being gripped between the nut and the knob, preferably with a lock washer 44 also interposed. A spring washer 49 received on the projecting portion of the pivot rod 55 between the lock nut 43 and the outside face of the housing 1 is compressed in assembly and reacts to draw shoulder 56 of the pivot pin 46 against the inside face of the journal boss 51. This spring washer thus imposes a frictional restraint to turning of the air gate relative to the boss 51 to maintain the gate in different positions of adjustment to which it may be shifted.

Within the bore hole in the boss the portion 55 of the pivot pin is engaged by the inner end of a piston-like cylindrical clamping element 57 slidable axially in a threaded bore hole which intersects radially the bore in which the pivot pin is journaled. Recessed set screw 58 is received in the threaded radial bore to exert axial pressure on the clamping element 57 and force the latter against the portion 55 of the pivot pin.

In adjusting the air control the set screw 58 is backed off to relieve the pivot rod portion 55 of clamping pressure so that the latter may be turned in adjusting the air flow as by the knob 60 which, as mentioned above, is secured on the end of the rod which projects cantilever fashion through the main housing wall 1. The pointer 62 swings across the face of a scale inscribed or embossed on the outside surface of the housing wall 1 and constitutes an indicator which shows the relative position of the air gate in the passage 12. After adjustment of the burner has been effected, the turning of the air gate 45 to different positions being under the frictional restraint imposed by the spring washer 49, the set screw 58 is tightened so that the clamping element 57 is made to bear radially or in endwise relation against the pivot rod to prevent turning of the latter and to thereby lock the air control gate in adjusted position. Engagement of the cylindrical surface of the rod portion 55 by the flat end face of the clamping element 57 not only distributes the pressure along an axially extending line of contact between the parts but also permits slight offsetting of the axis of the set screw bore with respect to the desired intersection with the axis of the journal bore for the pivot rod 55. It is difficult and costly to obtain perfect location of the bore holes so that their axes intersect. Yet when one axis is offset with respect to the other an objectionable turning of the air gate support rod is likely to result from the use of conventional set screw arrangements. The interposed piston-like clamping element of the present invention eliminates such disturbance of the air gate setting upon tightening of the locking set screw. Turning of the set screw is effected as by a screw driver received in its slotted outer end.

In the adjustment of the gate 45 to obtain different air flow conditions bottom edge 64 of the gate moves to different positions across the connecting passage 12 so that air being forced through the connecting passage and into the air receiving chamber 10 in the bottom portion of the burner housing is deflected various amounts by the air gate. The air gate thus regulates not only the rate of air flow from the fan chamber into the receiving chamber 10 but also the direction of the flowing air. While it is highly desirable that air be introduced tangentially into the receiving chamber 10, it has been found beneficial at some fuel burning rates to introduce some of the air radially or with strong radial components which avoids low pressure effects in the center of the air column and the air mass discharged from the air tube or the burner head on the latter and minimizes the tendency of the flame to be drawn back toward the fuel nozzle with attendant burning of the nozzle.

By the arrangement of the air control system of the present invention, in which the air control gate swings on a pivot about an axis at the outer periphery of the path of air discharged tangentially from the fan chamber, the axis being normal to the plane of rotation of the air mass in the fan chamber, there is a beneficial shifting of the line of entry of air flowing into the receiving chamber. It is essential, however, that a fractional portion of the air enter the receiving chamber tangentially. The open ing 54 in that part of the air control gate located adjacent the side wall of the housing and at or relatively close to the pivot axis of the gate provides a passage for part of the air tangentially discharged from the fan chamber to flow through the connecting passage 12 without substantial obstruction and tangentially to enter the receiving chamber under the guidance of the curved lower wall portion 3 of the housing. The gate opening 54 extends approximatcly half way across the gate width and be tween about one-fifth to two-fifths, here about one-third, of the gate length. The exact dimensions of the opening 54 are not critical, since the beneficial effects of the combined tangential and radial entrance of air into the receiving chamber 10 are obtained with proportions other than indicated. For eifective results, however, the bypass opening 54 should be from about 10% to about 25% of the total air gate area. The area of the cut-out is sutficiently large so that with the air gate at its limit of movement across the connecting passage, the cut-out passes enough air to maintain combustion at the minimum oil or fuel rate for which the burner is designed. The opening 54 may be located with some beneficial elfect at any point across the width of the air gate, although its location. as shown, adjacent the rear Wall 1 of the housing and remote from the air tube 16 insures that the portion of the air which enters the receiving chamber tangentially does so closely adjacent the rear wall 1, and the spiraling action of the air thus extends or prevails through the full length of the air receiving chamber.

It is thus apparent that the present invention provides an air control system wherein a swingable control gate varies the direction of flow of most of the air entering the receiving chamber of the housing While yet maintaining tangential entrance of a predetermined minimum frac tional portion of the air to induce the desired spiral How to the air mass in the air receiving chamber. The structural arrangement of the present air gate permits easy adjustment of the air flow from outside the burner housing while the burner is in operation. Provision is made for frictional restraint on the swinging movements of the air gate so that the latter readily may be shifted to and held in any desired position of adjustment during the burner adjusting operation and can thereafter be locked or clamped in adjusted position.

In accordance with the patent statutes the principles of the present invention may be utilized in various ways, numerous modifications and alterations being contemplated, substitution of parts and changes in construction being resorted to as desired, it being understood that the embodiment shown in the drawings and described above and the particular method set forth are given merely for purposes of explanation and illustration without intending to limit the scope of the claims to the specific details disclosed.

What I claim and desire to secure by Letters Patent of the United States is:

I, In a fluid burner. a housing comprising a substantial y fiat main wall and a plurality of outer and partition walls substantially normal to the main wall. said walls being arranged to define fan scroll and air receiving chamhers and a passage connecting the chambers. a boss integral with the main wall and located adjacent the con necting passage and one of the outer walls. a pivot pin supported by the boss. and an air control gate mounted on the pivot pin for swinging movement to diiferent passage adjusting positions, the gate having top and bottom edges. the gate being mounted on the pivot pin at the top edge, the gate being formed with a cutout to accommodate the boss and to provide an opening through the gate adjacent the pivot axis of the latter for the flow of air moving in the passage from the fan chamber to the receiving chamber, the cut-out being adjacent the main wall and adjacent the pivot pin and being located between the pivot pin and the bottom edge of the gate, whereby in all positions of adjustment of the gate in varying the effective area of the connecting passage the cutout provides. a minimum opening for air traveling a path along said one outer wall.

2. In a fluid fuel burner, 21 housing comprising a substantially flat main wall and a plurality of outer and partition wall portions substantially normal to the main wall, said wall portions being arranged to define fan scroll and air receiving chambers and a passage connecting the chambers, a boss integral with the main wall and located adjacent the connecting passage, a pivot pin comprising a circular sectioned portion journalled in the boss and a non-circular sectioned portion projecting from the boss cantilever fashion into the interior of the housing, the circular sectioned portion projecting through the main wall to the housing exterior, an air control gate having top and bottom edges, the top edge being afiixed to the noncircular portion of the pin for swinging movement to different passage adjusting positions, means on the portion of the pin which projects through the main wall for manually shifting the gate to different positions of adjustment, the pin being formed with a shoulder at the juncture of the circular and non-circular portions, and resilient means biasing the pin axially outwardly to hold the shoulder against the boss in the provision of frictional restraint against turning of the pin, the housing main wall being between the shoulder and the resilient means.

3. In a fluid fuel burner of the type comprising air pump housing means defining a fan chamber, an air receiving chamber of generally circular section and a passage connecting the chambers for conducting air from the fan chamber to the receiving chamber, an air tube having an interior chamber of generally circular cross section continuous with and disposed as a coaxial extension of the air receiving chamber, said passage being connected to the air receiving chamber through an opening into one side of the latter and being disposed normally to discharge air received from the fan chamber substantially tangentially into the receiving chamber whereby such discharged air rotates in the receiving chamber and advances as a column through the air tube while rotating spirally about the axis of the receiving chamber and the air tube; the combination of a gate and means mounting the gate for swinging movement in the connecting passage about an axis substantially parallel to the air chamber and tube axis about which the advancing air column rotates for intercepting air from the fan chamber and adjusting the rate of air flow into the receiving chamher, the gate having one end substantially at the pivot axis, the gate extending from the pivot axis in the general direction of air flow moving through the connecting passage from the fan chamber to the receiving chamber and having another end which moves in an arc during swinging movement of the gate between a high rate position in which the opening into the air receiving chamber from the connecting passage is substantially unobstructed by the gate and the air is discharged into the receiving chamber primarily tangentially, and a low rate position in which such opening is substantially closed by the gate, and said other end of the gate moving toward the plane defined by the parallel pivot and air tube axes in such swinging movement from high to low rate positions, whereby in adjusting the gate from said high rate pri marily tangential flow position toward the low rate position the air intercepted by the gate is deflected with a progressively greater component being discharged radially into the receiving chamber to increase turbulence and decrease spiral rotation of the air column.

4. In an oil burner having a housing providing a fan chamber, a chamber for receiving air from the fan chamber and a passage so connecting the chambers that air discharged from the periphery of a mass of air rotating in the fan chamber flows substantially tangentially therefrom through the connecting passage and substantially tangentially into the receiving chamber, the improvement which comprises a gate mounted on the housing and movable to different adjusted positions across the connecting passage to control the flow of air through the latter, said gate being formed with an opening substantially in the path of the outermost portion of air discharged peripherally from the fan chamber, said gate opening being of substantially the same area in all positions of adjustment of the gate, whereby in movement of the gate from relatively open to relatively closed positions the effective area of the said gate opening is undiminished and as the gate is progressively closed a predetermined minimum and undiminishing portion of the outermost peripherally discharged air passes through the gate opening to enter the receiving chamber tangentially.

5. In an oil burner having a housing providing a fan chamber, a chamber for receiving air from the fan chamber and a passage so connecting the chambers that air discharged from the periphery of a mass of air rotating in the fan chamber flows substantially tangentially therefrom through the connecting passage and substantially tangentially into the receiving chamber, an air control gate, and means mounting the gate for swinging movement to difierent passage adjusting positions about an axis substantially at the outer periphery of such rotating air mass, said gate being formed with an opening substantially in the path of the outermost portion of air discharged peripherally from the fan chamber, the gate having an edge spaced from its swing axis and which describes an arc during such adjusting movement, said gate opening including a portion located intermediate such edge of the gate and said swing axis and closely adjacent the latter, and said gate opening being of substantially the same area in all positions of adjustment of the gate, whereby in the movement of the gate from relatively open to relatively closed positions the effective area of the said gate opening is undiminished and as the gate is progressively closed a predetermined minimum and undiminishing portion of the outermost peripherally discharged air passes through the gate opening to enter the receiving chamber tangentially.

6. In a fluid fuel burner, a housing comprising a substantially flat main wall and a plurality of outer and partition wall portions substantially normal to the main wall, said wall portions being arranged to define fan scroll and air receiving chambers and a passage connecting the chambers, a boss integral with the main wall and located adjacent the connecting passage, a pivot pin supported by the boss, and an air control gate mounted on the pivot pin for swinging movement to different passage adjusting positions, the gate being formed with a cut out to accommodate the boss and to provide in all positions of adjustment a minimum opening through the gate adjacent the pivot axis of the latter for the flow of air moving in the passage from the fan chamber to the receiving chamber.

7. In a fiuid fuel burner, a housing comprising a substantially flat main wall and a plurality of outer and partition wall portions substantially normal to the main wall, said wall portions being arranged to define fan scroll and air receiving chambers and a passage connecting the chambers, a boss integral with the main wall and located adjacent the connecting passage, a pivot pin journaled in the boss and projecting through the main wall, an air control gate mounted on the pivot pin for swinging movement to different passage adjusting positions, the gate being formed with a cut out to accommodate the boss and to provide in all positions of adjustment a minimum opening through the gate adjacent the pivot axis of the latter for the flow of air moving in the passage from the fan chamber to the receiving chamber, and means having connection with the projecting portion of the pivot pin for shifting the gate to different positions of adjustment.

8. In a fluid fuel burner, a housing comprising a substantially fiat main wall and a plurality of outer and partition wall portions substantiaily normal to the main wall,

said wall portions being arranged to define fan scroll and air receiving chambers and a passage connecting the chambers, a boss integral with the main wall and located adjacent the connecting passage, a pivot pin journaled in the boss and having cantilever portions projecting one into the interior of the housing and another through the main wall to the housing exterior, an air control gate mounted on the one cantilever portion of the pin for swinging movement to different passage adjusting positions, the gate being formed with a cut out to accommodate the boss and to provide in all positions of adjustment a minimum opening through the gate adjacent the pivot axis of the latter for the flow of air moving in the passage from the fan chamber to the receiving chamber, and means secured on the other cantilever portion of the pin exterior to the housing for turning the pin in shifting the gate to different positions of adjustment.

9. In a fluid fuel burner, a housing comprising a substantially fiat main wall and a plurality of outer and partition wall portions substantially normal to the main wall, said wall portions being arranged to define fan scroll and air receiving chambers and a passage connecting the chambers, a boss integral with the main wall and located adjacent the connecting passage, a pivot pin comprising a circular sectioned portion journalled in the boss and a non-circular sectioned portion projecting from the boss cantilever fashion into the interior of the housing, the circular sectioned portion projecting through the main wall to the housing exterior, an air control gate having top and bottom edges, the top edge being mounted on the non-circular portion of the pin for swinging movement to different passage adjusting positions, means on the portion of the pin which projects through the main wall for manually shifting the gate to different positions of adjustment, the pin being formed with a shoulder at the juncture of the portions, and resilient means biasing the pin to hold the shoulder against the boss in the provision of frictional restraint against turning of the pin.

10. In a fluid fuel burner, a housing comprising a substantially fiat main wall and a plurality of outer and partition wall portions substantially normal to the main wall. said wall portions being arranged to define fan scroll and air receiving chambers and a passage connecting the chambers, a boss integral with the main wall and located adjacent the connecting passage, said boss being formed with intersecting journal and set screw bores, a pivot pin journalled in said journal bore, an air control gate having top and bottom edges, the top edge being mounted on the pivot pin for swinging movement to different passage adjusting positions, a cylindrical clamping element disposed in the set screw bore and formed on one end with a substantially flat surface arranged to bear against the pivot pin, and a set screw threadedly received in the set screw bore and arranged to bear against the other end of the clamping element to force the latter against the pivot pin and thereby to clamp the latter in adjusted position, the set screw being rotatable independently of the clamping element.

11. In a fluid fuel burner of the type comprising air pump housing means defining a fan chamber, an air receiving chamber of generally circular section and a passage connecting the chambers for conducting air from the fan chamber to the receiving chamber, an air tube having an interior continuous with and disposed as a coaxial extension of the air receiving chamber, said passage being connected to the air receiving chamber through an opening into one side of the latter and being disposed normally to discharge air received from the fan chamber substantially tangentially into the receiving chamber whereby such discharged air rotates in the receiving chamber and advances as a column through the air tube while rotating spirally about the axis of the receiving chamber and the air tube; the combination of a gate and means mounting the gate for swinging movement in the connecting passage about an axis substantially parallel to the air cham' 11 her and tube axis for intercepting air from the fan chamher and adjusting the rate of air flow into the receiving chamber, the gate having one end substantially at the pivot axis, the gate extending from the pivot axis in the general direction of air flow moving through the connecting passage from the fan chamber to the receiving ch2|mher and having another end which moves in an arc during swinging movement of the gate between a high rate position in which the opening into the air receiving chamber from the connecting passage is substantially unobstructed by the gate and the air is discharged into the receiving chamber primarily tangentially, and a low rate position in which such opening is substantially closed by the gate, said other end of the gate moving toward the plane defined by the parallel pivot and air tube axes in such swinging movement from high to low rate positions. whereby in adjusting the gate from said high rate primarily tangential flow position toward the low rate position the air intercepted by the gate is deflected with a progressively greater component being discharged radially into the receiving chamber to increase turbulence and decrease spiral rotation of the air column, and the gate being formed with a cutout at said one end adjacent the pivot axis through which a predetermined and undiminished proportion of the air received from the fan chamber lay-passes the air gate and enters the receiving chamber tangentially when the gate is being adjusted to and is at the low rate position.

References Cited in the file of this patent UNITED STATES PATENTS 787,039 Harris Apr. ll, 1905 960,815 Carlisle June 7, 1910 2,075,587 Mesinger Mar. 30. 1937 2,215,281 Von Haase Sept. 17, 1940 2,236,865 Bailey et al Apr. l94| 2,478,457 Camerino et a1 Aug. 9, 1949 2,599,153 Beckett June 3, 1952 2,645,411 Andler July 14, 1953 FOREIGN PATENTS 20,848 France Apr. 24v 1858