US2386462A - Heater - Google Patents

Description

Oct. 9, 1945.

FL. 0. HESS HEAT ER Filed Sept. 4, 1941 2 Sheets-Sheet 1 1L INVENTOR l FEEDER/C QHEss v ATTORNEY F. O. HESS HEATER 2 Sheet-Sheet 2 Filed Sept. 4, 1941 ATTORNEY ll W H WI J INVENTOR ffefflfe/c 0 #555 Patented Oct. 9, 1945 HEATER- Frederic 0. Hess, Germantown, Pa., assignor to Selas Corporation of America, a corporation of Pennsylvania Application September 4, 1941, SeriaiNo. 409,440

14 Claims.

heating is desirable, and for defrosting and other purposes.

A more specific object of the invention is to provide a simple, light weight heater structure, adapted to burn any ordinary airplane engine fuel, and in particular to burn gasoline which has been lead treated to increase its octane rating, and from which lead tends to separate when the gasoline is vaporized. Another specific object of the invention is to provide a heater characterized by the simplicity and efiectiveness of its operation and by the ease with which its heating efiect may be controlled.

Another specific object of the present invention is to provide a heater embodying a heat exchange structure of novel and desirable form to enclose the heating space thereof and to transfer heat from such heating space to air moving over its outer wall.

Heretofore airplane heating provisions have customarily been ofa type to utilize airplane engine waste heat. The use of such airplane heat- Fig. 6 is a plan section of a third form of finned wall structure;

Fig. '1 is a perspectivewiew of one of a multiplicity of sheet metal parts employed in the construction shown in Fig. 6;

Fig. 8 is a view taken similarly to Fig. 6 illustrating another finned wall structure modification; and

Fig. 9 is a partial section on the line 9-9 of Fig. 8.

The heater structure illustrated by Figs. 14, comprises a base member or burner body A, which may be an aluminum casting and is formed with an annular burner inlet chamber B. As shown,

the chamber B is open at its upper side, and adjacent the upper edges of the inner and outer side walls of the chamber, the member A is recessed to provide a seat for an annular orifice wall C which separates the burner inlet chamber B from the annular combustion space W of the heater. Advantageously, the orifice wail C is formed of thin radially extending plate-like members of ceramic material,'having orifice formin grooves in their sides adapted to pass a coming provisions under some present day operating conditions gives rise to a number of practical disadvantages which may be avoided by the use of the present invention.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, however, its advantages, and specific objects attained with its use, reference should be had to the accompanying I drawings and descriptive matter in which I have illustrated and described a preferred embodiment of the invention.

Of the drawin'gs:

Fig. 1 is a sectional view of a heater embodyin the invention;

Fig. 2 is a plan section taken on broken line 2-2 of Fig. 1, but with parts broken away to show portions of the heater at a level immediately above the heater fuel burner;

Fig. 3 is a plan view of a partially constructed portion of a finned heat exchanger element;

Fig. 4 is a perspective view of one of the structural parts included in the element shown in Fig. 3;

Fig. 5 is an elevation in section of a portion of a finned wall structure of modified form;

bustible mixture into the combustion chamber, generally as disclosed in my prior Patent No. 2,228,114, granted January 7, 1941.

The combustion space W is immediately adjacent the burner body A and in communication with a heating space D having inner and outer walls formed by Z-shaped sheet metal parts e and E, respectively, associated with other parts of the heater, ashereinafter described. The air to be heated moves upward through air spaces F and f, respectively, at the outer and inner sides of the annular combustion and heating spaces W and D. The spaces F and f are open at their lower ends to receive air to be heated from the space.

in which the heater is located and discharge said air in a heated condition at their upper ends. As shown, the air heated is drawn through the spaces F and f by an exhaust fan or blower H located in an outlet chamber G into which the spaces F and f open.

Except for the form and disposition of the parts E and e forming the side walls of the combustion and heating spaces W and D, the heater shown in Figs. 1 and 2, insofar as it has already been described herein, is generally similar to the aircraft heater disclosed in my prior application, Serial No. 348,324, filed July 29, 1940, of which the present application is a continuation in part.

In the construction shown, J is the impeller 01 a turbo type blower having its outlet J opening to the chamber B and receiving air through an which drives the fan or blower H is indirectly supported by said body through a cage-like frame I. The described means for supplying a mixture of combustion air and atomized gasoline to the inlet chamber of the burner of an airplane heater is a joint invention of John W. Townsend and myself, and is described and claimed in our appliinner wall is received in a similar slot formed in a ring I similar to the ring L and forming a clamping ring engaging the inner ends of the ori-- tively, and the heating space D is closed at its cation, Serial No. 365,804, filed November 15,

1940, now Patent No. 2,314,089, granted March 16, 1943.

In accordance with the present invention each of the previously mentioned parts E which collectively form the outer wall of the combustion and heating spaces W and D, is in the form of a Z- shaped thin strip or bar of suitable metal, which may be stainless steel, and comprises parallel, laterally displaced, side edge or fin portions E' integrally connected to one another by and extending away from the opposite sides of a central or body portion of the member which is generally transverse to each fin portion. The central or body portion of each member E is inclined at a small angle to a plane transverse to the fin portions E, so that the central portions of the members E may be arranged side by side in a row, and overlap as shown in Fig. 3, with the fin portions E of adjacent members E spaced apart by a distance somewhat less than the width of the body portion of a member E.

In forming the outer wall of the combustion and heating spaces W and D, the adjacent parts E thereof and their overlapping body portions may advantageously be connected by seam welding, or by spot welding at points distributed along the lengths of the members at intervals of a half inch or so. After enough members E have had their body portions welded together to form a finned sheet like that shown in Fig, 3 and of suflicient length, the sheet is bent into circular form and the overlapping body portions of the parts E at the ends of the sheet are welded together. In forming the parts E, the ends of the fin portions E are cut away so that at each end of the cylindrical wall formed by the assembled parts E, the ends of the overlapping central body portions of the members E unite to form a cylindrical flange-like connection portion E of the wall projecting beyond the finned portion of the wall.

The Z-shaped parts e forming the inner wall of the heat exchanger are generally similar in form to the parts E, each comprising a central body portion and edge portions e generally transverse to the body portion. The parts e are arranged and connected to form the inner Wall of the combustion and heating spaces, as the parts E are arranged and connected to form the outer wall of these spaces. The inner cylindrical wall formed by the parts e, comprises top and bottom cylindrical flange portions 6 similar to the flange portions E of the outer wall.

As shown, the bottom flange E of the outer wall is received in a circular slot extending downward into a metallic ring L which may be a brass ring and forms a clamping member engaging the outer ends of the ceramic'laminae forming the burner orifice wall C. The bottom flange e of the upper end by an annular top wall member 0. The part 0 is provided at its inner and outer edges with downwardly extending flanges O. The cylindrical wall part M which forms an upper end extension of the outer wall of the heating space D formed by the parts E, is provided with a bottom groove, slot, or pocket receiving the upper flange E of said parts and with a groove, slot, or pocket at its upper end receiving the outer edge flange O of the member 0. Advantageously and as shown, the part M is formed by two nesting rings of sheet metal, which may be united by spot welding, and one of which has upper and lower edge portions laterally displaced from an intermediate body portion of the member to provide the slots receiving the flanges 0 and E The wall part m may be similar in form and construction to part M and has a similar tongue and groove connection with top flange e of the wall part formed by the members 6, and with the inner edge flange of the part 0.

N' indicates a horizontal outlet pipe through which products of combustion pass away from the upper end of the heating space D. lAdvantageously, an electric motor driven exhaust fan JA impresses a suction on the heating space D through the outlet N, so as to maintain a subatmospheric pressure in the heating space and thereby insure that leakage if any through the heating space wall with its multiplicity of joints will be into and not out of said chamber.

As shown, the above described heat exchanger wall structure is clampedin place against the burner body A by clamping elements shown in Fig. 2 as three in number. Each of said elements comprises two clamping bolts P extending through the web portion A' of the burner body and comprises a clamping bar P extending over the top member 0, and to the opposite ends of which the upper ends of the said two bolts P are connected. As shown, one bolt P of each clamping element is located in the outer heat exchanger air space F and the other bolt is located in the inner air space 1.

The heat exchanger of Figs. 1 and 2 comprises a cylindrical outer casing Q which advantageously is formed of sheet metal and which fits snugly against and may be weldedor brazed to the outer 'edges of the outer fins E of the member E. As

shown, the upper end portion of the casing member Q comprises successive short sections of successively reduced diameter and terminates at its upper end in a short cylindrical portion ED which overlaps and is clamped against a depending cylindrical flange portion G of the member G. At its lower end, the casing member Q may be connected as by means of small screws to the outer ends of the arm A of the burner body A.

As shown, a battle or partition member R'in the form of a hollow conical frustum formed of sheet metal, has its lower edge welded or otherwise con nected to the part 0. The member R in conjunction with an adjacent inclined portion ofthe casing member Q provides a converging annular channel or orifice through which heated air passes from the outer air space F to the opening G in the underside of the member G, which forms the air'inlet for the fan H. A part 8 of circular cross section comprises a lower cylindrical portion which fits against the inner edges of the fins e' and may be welded thereto and an .upper-portion which decreases in diameter from G. To preclude Joint leakage asbestos or other,

suitable packing material may be inserted in the pockets of the members L, l. M and m receiving the various flanges E", e and O.

In the normal contemplated operation of the air heater shown, a suitable draft diiferential is provided for moving combustible mixture from the burner inlet chamber 3 into and through the orifices in the ceramic burner wall into the combustion space W, and for moving products of combustion from space W through the heating space D and thence through the outlet N. This is created in part by the fan J and in part by the exhaust fan JA or other draft suction creating means for impressing a draft suction effect on thegases passing away from the heating space D through the outlet N. In practice, suitable electrical ignition means (not shown) may be prospace in which the heater is located, or may pass partly into that space and partly into conduits (not shown) for conveying the air to other portions of the airplane structure, where heating effects are desired. As shown, below the level of the bottom edge of the member S the air space I is not separated from the central heater space including the motors h and 7, and some of the air passing into the heater structure through the central-opening A in the burner body A sweeps over the motors and passes into the member G through the member S. This provides a desirable motor cooling eifect, and the heat thus absorbed from the motors, as well as the heat supplied by the combustion of fuel in the combustion chamher, is used in heating the air discharged by the heater. The means including the fan H and casing G for distributing the air heated through a plurality of outlets are disclosed and claimed in the joint application, Serial No. 409,613 filed September 5, 1941, by Richard E.-B. Wakefield and myself. a

As will be apparent to those skilled in the art, the parts E and e may be formed rapidly and at a relatively low cost, from suitable strip material. The heat exchanger wall blank shown in Fig. 3 can be built up rapidly and at a relatively small expense owing to the ease with, which parts E may be added, one at a time, to the previously formed portion of the blank. As is apparent from Fig. 3, adequate access for seam or spot welding purposes is provided at the end of the blank where needed for the attachment of a new part E. The character of the construction is well adapted for use with parts E and e made of sheet metal which is quite mm and thus permits of high heating capacity per unit of heater weight.

The heater construction may be rapidly assembled and rapidly disassembled and then reassembled when necessary forcleaning, inspection or repair purposes. To insure the predetermined relative disposition of parts required for the proper placement of the outlet N, and for the proper placement of\ control and other accessory parts (not shown) it is, in general, desirable that the relative angular positions of the burner body and the heat exchanger walls should always be the same. To insure such relative positions, the rings L and I may each be provided at, its underside 'with a dowel pin T which in the assembled apparatus extends into and fits in a corresponding hole formed in the burner body A, and the heat exchanger walls formed by the parts E and e may be welded or brazed or otherwise permanently attached to the corresponding rings L and l.

The heat exchanger wall structure illustrated in and by Figs. 1-4 may be modified in various ways, and different modifications thereof are shown in Fig. 5, in Figs. 6 and 7, and in Figs. 8 and 9.

In the modification shown in Fig. 5, the side walls of the heat exchanger are formed of sheet metal parts EA and ea which may be formed from flanged stock strips of sheet metal-like those from which the parts E and e first described are made. The parts EA and ea differ from the parts E and e V respectively in having more of their-fin portions cut away at their upper ends, so that the overlapping central body portions E and e of the parts EA and da above the upper ends of the fins are long enough to take the place of the special parts M and m of the construction first described. In Fig. 5 the annular heat exchanger top wall 0 has its depending-inner and outer flanges 0' received in slots formed respectively in the upper side of corresponding ring members LA and la. The rings LA and la. may be die cast parts exactly like the lower ring parts L and 1, except that each of the rings LA and la is also formed with a slot in its-under side which receives the upper ends of the corresponding portions E or. e, respectively.

Under some conditions the manufacturing cost of the structure shown in Fig. 5 is substantially .side wall to stresses which inevitably result in the wall losing its cylindrical form when the upper ends of the parts E or e includedin such a side wall as is shown in Figs. 1 and 2 are disconnected from the part M or 111.. When dis-- assembling the apparatus for cleaning or repairs it is ordinarily practically essential to separate the heat exchanger top wall from its side walls but it is not necessary to separate the finned side wall parts from the end rings L, LA, I or la connected thereto.

It is to be noted that in the construction shown in Fig. 5 a considerable portion of the upper ends of thefins which extend into the heatin space DA must be cut away to provide a channel for the horizontal flow of products of combustion through the outlet N. Itis not necessary to provide for such horizontal flow at the bottom portion of the heating space DA or combustion space WA, but it is desirable to cut away the lower ends of the fins at the'lower ends of the fin side wall members to prevent an excessively rapid absorption of heat and the resultant burning of the thin stainless steel sheet metal parts which collectively form the side walls and fins defining the space WA immediately adjacent the burner body A in which combustion or burning of the-combustible fuel mixture takes place and from which heated products of combustion pass upwardly into the heating space DA of the heat exchanger.

In the modified form of the'heat exchanger wall structure shown in Figs. 6 and 7, the two side walls are formed by different portions of a multiplicity of similar sheet metal parts EB. Each wall part EB may be formed from a flat blank of sheet metal rectangular in outline which is bent or stamped to form a longitud nally extending trough shaped depression, so that the bent or stamped wall comprises inner and outer portions E and E lying in the same plane, a trough bottom portion E in a plane parallel to but laterally displaced from the first mentioned plane, and transverse portion E and E forming the side walls of the trough and connecting the trough bottom wall to the portions E and E31 respectively.

In the assembled combustion chamber wall structure including .the parts EB, the latter are radially disposed and have their trough portions in nesting relation with their trough side wall portions E and E overlapping one another and connected by spot or seam welding. The trough bottom walls E thus serve as heat absorbing fins extending into the heating space DA, and the outer and inner side portions E and E of each part EB constitute fins extending across the outer and inner air spaces F and f. The fin portions of the members EB may be cut away, as indicated at W in Fig. 7, to form the annular shaped combustion space WA adjacent to and i in the immediate vicinity of the burner body.

By providing the burner wall having a plurality of orifices, the combustible fuel mixture supplied to the burner is divided into a plurality of small gas streams which are discharged from the top 4 surface of the wall C at which region burning and combust on of the combustible fuel mixture takes place. The burning of the combustible fuel at the top surface of the burner wall C in the manner just described insures the production of high temperature heated products of combustion in the combustion space WA from which substantially completely burned gases pass upwardly through the heating space DA formed by the spaced-apart finned walls of the heat exchanger.

The overlapping ends of the side wall port ons of the parts EB may be connected to ring members L, 1, LA, and la, as in the construction previously described, or as shown in my prior application, Serial No. 348,324, they may be welded or brazed to other portions of the heat exchanger structure. The outer edges of the fin portion E and the inner edges of the fin portionsE advantageously engage cylindrical casing 'members which may be, and as indicatedare like the casing parts Q and S of the construction first described.

The finned wall structure shown in Figs. 8 and which differ from the parts EB only in that the trough portionE 0! each part EC is in the general form of a half cylinder with generally tangential edges. Advantageously, also transverse grooves or hollow ribs ii? are formed in the crown of each trough portion E. As plainly shown in Fig. 9 the hollow ribs E of each plate EC are too short to extend into the tangential edge portions of the trough portion E and those edge portions overlap and lit against and are weld d to the similar portions of the adjacent members EC. The construction shown in Figs. 8 and 9 has a practical advantage in that the rounded shape of the trough portions of the parts EC facilitate proper nesting of the parts, as shown in Fig. 8, and the parts EC may be readily formed by relatively simple sheet metal stamping dies. The provision of the ribs E gives added stiffness to the heat exchanger structure and serves the special purpose of eliminating the tendency of the curve plate portions E to flatten out somewhat as the stamping dies are opened to release the plate EC in which said portion has been formed.

It will now be understood that an independently operableheater has been provided in which the walls formed by the Z-shaped parts E and e and extensions M and m form a hollow heat radiating unit having a relatively extensive heat transfer surface. The heat radiating unit formed bythe parts E and e and extensions M and m provides a substantially unobstructed passageway from the inlet adjacent the burner body A to the outlet N through which the products of combustion are discharged. The passageway of the heat radiating unit is considerably longer than th distance between the walls formed by the parts E an e and in a range in which the length of the passageway from the inlet end to the outlet end is more than seven times the average distance between the walls.

The inlet includes the wall C having a multiplicity of apertures therethrough to subdivide the mixture into a plurality of small gas streams so that substantially complete combustion of the streams may be accomplished in the combustion space W adjacent to the wall C. The wall C at the inlet is elongated and annular in form and one dimension thereof, namely, the circumference, is considerably greater than its other dimension which is the distance between the walls of the heat radiating unit. The burner body A and the apertured wall C form the elongated manifold or inlet chamber B which is co-extensive with the inlet and communicates with the outlet passage J of the blower within which the fan J is disposed. The outlet passage J forms a relatively short connection from the blower to the manifold B, and, together with the blower, provides a closed path .flow for supplying to the manifold combustion upporting air received through the inlet pipe J.

The fuel is adapted to be supplied under pressure through the pipe 7' as explained above, having its discharge orifice terminating in the closed path of air flow at a region thereof at which turbulent movement of air is effected, so that an intimate combustible mixture of air and fuel may be produced for delivery to the manifold B.

Heaters of the type disclosed herein have an inherent capacity for easily efiected and suitable regulation, and have been found to be well adapted for their intended uses. Eificient combustion of the combustible mixture of air and atomized gasoline can be readily maintained in the comi .a,seo,4oa bustion space of the heater at such rate as to inches, is adapted to liberate about 1200 B. t. u.s

per minute in regular operation and that its heat exchanger walls will become heated to an elevated temperature in less than a minute after the heater (initially in a 'cold condition) is started into operation without air flow through spaces F and f. V I

While in accordance with the provisions of the statutes, I have illustrated and described the best form of embodiment of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departing from the spirit of my invention, as set forth in the appended claims and that in some cases certain features of my invention may be used to advantage without a corresponding use oi other features. Having now described my invention, what I claim as new and desire to secure by Letters Patent, is: a

1. An air heater comprising a burner body 7 formed with an annular slot-like inlet chamber,

an orifice wall mounted on said body and extending across the open side of said slot, and an annu- Q lar chamber having an end communicating with said orifice wall, said chamber having inner and outer cylindrical side walls formed of thin metal an having fins intermediate their ends, and a' separate metal ring interposed between each of said side walls and burner body and formed with a slot receiving the adjacent end of the corresponding side wall.

, an orifice wall mounted on said body and extending across the open side of said slot, and an annular chamber having an end communicating with said orifice wall, said chamber having inner and said side walls and said burner body and formed with a slot receiving the adjacent end of the corresponding side wall, an end wall connecting the side walls of the chamber at their ends remote" iron the burner body, and. means acting between said end wall and said burner body to clamp the side walls of said chamber and burner body totending across the open side of said slot, and an annular chamberhaving an end communicating with said orifice wall, said chamber having inner and outer cylindrical side walls formed of thin metal and having fins intermediate their ends, a separate metal ring interposed between each of said side walls and burner'body, an end wall member connecting the side walls of the chamber at their endsremote from the burner body, each of said side walls having a tenon and socket connection with the corresponding metal ring and a tenon and socket connection with said end wall member, and means acting between said end wall and burner body .to clamp said end and side wall rings and burner body together comprising a clamping r extending over said end wall member and bol 'at the inner and outer sides of said chamber connecting the ends of said clamping bar to said burner body.

5. An air heater of the type specified, comprising a multiplicity of bent sheet metal plates arranged in an annular series about an axis, and comprising portions bent transversely to one another and nesting together to .form two or more annular series or channels surrounding said axis, each of. said plates being notched at one end to provide an annular combustion space to which the' channels of one of said series are each open at one end, means for supplying fluid fuel and air for combustion in said space, and means for another and nesting together to form an interouter cylindrical side walls formed of thin metal and having fins intermediate their ends, a sepa-- rate metal ring interposed between each of said side walls and said burner body and formed with an annular slot receiving the adjacent ends of the corresponding side wall, an end wall connecting the side walls of the chamber at their ends remote from the burner body and including edge portions extending toward said burner body, and a separate metal ring interposed between each of said side walls and said end wall and formed with a slot at one side receiving the corresponding end portion of said side wall and with a slot at its other side receiving the corresponding edge portion of said end wall.

3. An air heater comprising a v burner body formed with an annular slot-like inlet chamber, an orifice wall mounted on said body and extending across the open side of said slot, andan annular chamber having an end communicating with said orifice wall, said chamber having inner and outer cylindrical side walls formed of thin metal and having fins intermediate their ends, a

mediate annular series of channels and inner and outer annular series of channels, each of said plates being notched at one end to provide an annular combustion space to which the channels of said intermediate series are each open at one end, means for supplying fiuid fuel and air for .combustion in said space and for removing products of combustion from the ends of the last mentioned channel remote from said space, and means for moving air through said inner and outer channels.

7. An air heater of the type specified, comprising a multiplicity of bent sheet metal plates arranged in an annular series about an axis from which each of said parts extend in a general radial direction and comprising portions bent transversely to one another and nesting together to form an intermediate annular series of channels and inner and outer annular series of chanels, each of said plates being notched at one end to provide an annular combustion space to which the channels of said intermediate seriesare each open at one end. a burner having an annular orifice wall forming a wall for said space at the side thereof remote from the last mentioned channels, means for supplying fiuid fuel and air to said burner for combustion by the latter, and means for moving air to be heated through said inner and outer channels. 8. An air heater of the type specified, comprising a multiplicity of bent metal plates arranged in an annular series about an axis, and each comprising a trough-like portion intermediate its inner and outer edge portions, the said trough-like portions of the different plates nesting together to form an annular series of channels having their inner and outer edges closed by the nesting trough portions and from which said inner and outer edge portions are adapted to transmit heat to air inthe spaces between said edge portions, and means for passing heating gases through said channels.

9. An air heater of the type specified in claim 8 in which the trough portions of the metal plates are provided with projections at their ends and welded to one another.

10. An air heater as specified in claim 8, in which the trough portion of each plate is of round trough bottom form, and comprises integral transversely extending hollow stifiening rib portions.

11. A'wall for a heat exchanger having a group of fins projecting from each face thereof, said wall and fins comprising a number of similar Z-shaped strips of sheet metal each including a central portion and a pair of side portions or flanges projecting in opposite directions from and transverse to the central portion, said central portions having regions thereof overlying the central portions of two adjacent strips and secured thereto to form the wall and the flanges forming the twogroups of fins, and the central portions of said strips being longer than said flanges and extending beyond the edges of the lattier and to form the annular wall and the flanges forming the two groups of fins, and said central portions at one end of said strips extending beyond and from the flanges to form an annular wall section serving to facilitate connecting the annular wall in position.

13. A heat exchanger comprising an annular wall as set forth in claim 12, and including an annular member having a slot to receive said annular wall section.

14. In an independently operable heater of the class described having, in combination, a hollow heat radiating'unit including a pair of spaced apart walls providing a relatively extensive heat transfer surface,said unit having an inlet at one end for a combustible fuel mixture and an outlet at its opposite end for discharging products of combustion and a substantially unobstructed passageway from the vicinity of the inlet to the outlet, the length of said passageway from the inlet to the outlet being considerably greater than the distance between said walls and in a range in which the length of said passageway is more than seven times the average distance between said walls, said inlet including a wall having a multiplicity of apertures therethrough to subdivide the mixture into a plurality of small gas streams so that substantially complete combustion of the streams may be accomplished in said unit at and in the immediate vicinity of said apertured wall, said inlet being elongated and having one dimension considerably greater in extent than its other dimension, means including said apertured wall to provide an elongated manifold having an opening for introducing the mixture thereto, said manifold being co-extensive with the inlet, means including a blower and a relatively short connection therefrom to the manifold opening to provide a closed path of fiow for the combustion supporting air of the mixture, means to drive said blower to supply air under pressure to said manifold and cause turbulent movement of the air in said path of flow, and a fuel supply line through which fiuid fuel is adapted to be supplied under pressure, said line having a discharge orifice terminating in said path of flow to discharge fuel into a region thereof at which turbulent movement of air isefiected so" that an intimate combustible mixture ofair and fuel may be produced for delivery to said manifold.

FREDERIC O. HESS.

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