US3252496A - Fuel and air admitting valve assembly for pulse jet burners - Google Patents

Description

May 24, 1966 F'. :MAG 3,252,495

FUEL AND AIR ADMTTING VALVE SSEMBLY FOR l PULSE JET BURNERS Filed Deo. 19, 1955 5f Je m i /53 54 l l'", 052

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72nd@ "/f /Cer fmir/mwfy United seres Patent o J 13 claims. (cl. 15s-4) The present invention relates to pulse jet burners in general, and more particularly to an improved valve assembly which serves to control the admission of fuel and air or oxygen to such burners.

It is well known that a pulse jet burner may operate with many different types of fuel including fuels which react rapidly with oxygen or oxygen-containing air and fuels which are rather slow to react. The pulse jet burner must be constructed and assembled by careful consideration of the characteristics of fuel which is to be used because only then is the burner capable of operating with optimum etciency. If the fuel reacts rapidly, the admission of fuel and air (or oxygen) may occur in a Vfully automatic way, i.e., there isA no need to provide valves which admit fuel and air to the intake end of the suction duct or mixer tube which delivers the mixture of fuel and oxygen into the combustion chamber of the burner. In such instances, the burner dams dynamically in a fully automatic way so that no valves are needed for admission of fuel and oxygen because the fuel-air mixture or the products of combustion are not likely to be forced back into the fuel supply conduit. Such dynamic (valveless) damming improves ,if the pulse jet burner receives a fuel which reacts with oxygen very rapidly, i.e., which is easy to ignite, but the situation is different if the fuel is of the slowly reacting type. A pulse jet burner which is operated with slowly reacting types of fuel cannot prevent the mixture of fuel and oxygen or the products of combustion from traveling up the fuel supply conduit and/ or into the surrounding atmosphere so that such burners must be equipped with valves which control the admission of fuel and oxygen into the mixer tube of the combustion chamber. The need for such valves is particularly great when a pulse jet burner is started because a cold fuel is always slower to react.

Accordingly, it is an important object of the present invention to provide a very simple, exceptionally compact, highly reliable and fully automatic valve assembly which controls the admission of slowly reacting fuel and oxygen or oxygen-containing air into the mixer tube or directly into the combustion chamber of a pulse jet burner.

Another object of the invention is to provide a valve assembly Iof the just outlined characteristics wherein the valves which admit fuel and oxygen are combined into a compact unit and wherein such unit may form a readily separable attachment which may be secured to the mixer tube of a pulse jet burner.

A further object of my invention is to provide a pulse jet burner which comprises a valve assembly of the above outlined characteristics and which is especially suitable for use in various household appliances and apparatus, such as water heaters and the like, wherein the space is at a premium and wherein any, even smallest, savings in space are of great advantage.

An additional object of the invention is to provide a valve assembly which serves as a highly satisfactory mechanical damming device to prevent b'ackllow of fuel-air mixture or combustion products into the fuel supply conduit and/or into the surrounding atmosphere, and'which t fatter when is capable of automatically regulating the percentage of fuel in the mixture in such a way that the mixture will be the burner is started and that the mixture will be leaner when the burner has been heated up to normal operating temperature.

A concomitant object of the instant invention is to provide a valve assembly embodying the above outlined features and advantages and capable of reducing noise which develops on combustion of a fuel-air mixture in the combustion chamber of a pulse jet burner.

Still another object of the' invention is to provide an attachment which includes a valve assembly of the above outlined characteristics and which is assembled with a mixer tube in such a way that the fuel is heated automatically prior to its admission into the valve assembly.

A further object of the invention is to provide a valve assembly which may be readily separated from the pulse jet burner and which can be taken apart so that all of its parts may be inspected, cleaned or replaced with little loss in time and without necessitating the utilization of special tools.

With the above objects in view, one feature of the invention resides in the provision of a pulse jet burner which comprises a combustion chamber including a mixer tube, a valve assembly including a rst and a second valve for respectively admitting fuel and oxygen to the intake end of the mixer tube, and a fuel supply conduit comprising an annular sound absorbing chamber which surrounds at least a portion of the mixer tube and which delivers fuel to the first nozzle.

ln accordance with a more specific feature of the invention, the valve assembly comprises a substantially boxshaped housing having two apertured wall portions which constitute the seats of the valves. Each of these valves further comprises a stop spaced from the respective seat and a diaphragm or a similar valve member which is movable between the stop and the respective seat. One of the stops may be anchored in the housing and may comprise one or more projections which engage and hold the other stop at a requisite distance from the respective seat.

If necessary, the valve assembly may comprise more than one oxygen admitting valve.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved valve assembly itself, however, both as to its construction, operation and the mode of assembling the same, together with additional features and advantages thereof, will be best understood from the following detailed description of certain specific embodiments with reference to the accompanying drawings, in which:

FIG. 1 is a fragmentary axial section through a pulse jet burner which embodies one form of the improved valve assembly; and

FIG. 2 is a greatly enlarged fragmentary axial section through the valve assembly of FIG. l.

FIG. l illustrates a portion of a pulse jet burner with a single combustion chamber 10 one end portion of which forms a resonance duct (not shown) serving to receive and to convey gaseous products of combustion which develop on ignition of a fuel-oxygen mixture. The other end portion of this combustion chamber forms a suction duct 11, also called mixer tube, wherein air or pure oxygen is mixed with a suitable fuel, and the resulting mixture is thereupon ignited in the internal space of the combustion chamber proper or in the mixer tube. The operation of the pulse jet burner is well known and by itself forms no part of my invention. The burner of FIG. 1 is especially suited for use with a slowly reacting fuel and,

therefore, the admission of fuel and oxygen to the mixer tube 11 must be controlled by valves: in order to insure satisfactory damming, i.e., to prevent the reaction between fuel and oxygen from spreading into the fuel supply conduit. My invention relates to a novel valve assembly 15 which delivers oxygen and slowly reacting fuel to the mixer tube 11 and which prevents the explosion from spreading into the fuel supply conduit.

The valve assembly 15 comprises a substantially cup shaped base 16 and a cupped cover 17, and these two elements together form a substantially box shaped valve housing which is detachably secured to and is preferably coaxial with the mixer tube 11. The bottom wall portion 20 of the base 16 constitutes the valve seat of a fuel admitting valve and is provided with a centrally located tubular extension or nipple 18 whose internal diameter preferably equals or approximates the internal diameter of the mixer tube 11. The open discharge end of the nipple 18 is adjacent to but is somewhat spaced from the intake end of the mixer tube 11, and these parts are coaxial with each other. The bottom wall portion 30 of the cover 17 constitutes the valve seat of a first air admitting valve, and the base 16 comprises a second annular wall portion 40 forming the valve seat of a second air admitting valve. The valve seat 40 surrounds and is axially spaced from the valve seat 20, i.e., the plane of the valve seat 40 is located between the planes of the valve seats 20, 30.

The valve seats 20, 30, 40 are respectively provided with concentric groups of circularly arranged apertures 21, 31, 41. In the illustrated embodiment, the apertures 21, 31, 41 are of circular outline, but it is equally possible to use apertures in the form of arcuate slots whose center of curvature is located on the axis of the valve assembly 15. This assembly further comprises three annular arresting members or stops in the form of disks 22, 32, 42 which are provided in the interior of the valve housing and are respectively spaced from the valve seats 20, 30 and 40. It will be noted that the main body portion of each of these disks is located in a plane parallel with but slightly spaced from the plane of the respective valve seat, and each disk is provided with a series of circularly arranged openings 23, 33, 43 (see particularly FIG. 2) which may but need not be in exact registry with the respective apertures 21, 31, 41. The narrow compartment between the valve seat 20 and disk 22 accommodates an annular valve member 24, here shown as an elastic diaphragm whose marginal portion is guided by a cylindrical portion 20a connecting the periphery of the valve seat 20 with the innermost portion of the valve seat 40. A second elastic valve member in the form of a diaphragm 34 is located in the compartment between the valve seat 30 and disk 32, and a third annular valve member in the form of an elastic diaphragm 44 is received in the compartment between the valve seat 40 and disk 42. The marginal portion of the diaphragm 34 is guided by a cylindrical portion 30a of the valve seat 30, and a similar cylindrical portion 40a of the valve seat 40 guides the marginal portion of the diaphragm 44. Thus, each diaphragm is free to move in the respective compartment axially between a first position in which vit seals the apertures of the respective valve seat and a second position in which it seals the openings of the respective disk. When the diaphragms 24, 34, 44 respectively seal the apertures 21, 31, 41, the corresponding valves act as check valves and prevent the fluid or fluids contained in the interior of the valve housing from flowing outwardly. On the other hand, when the diaphragms 24, 34, 44 seal the openings 23, 33, 43, the respective valves permit entry of fuel and air into the interior of the valve housing and into the mixer tube 11. The openings 23, 33, 43 enable the pressure prevailing in the valve housing to act against the respective diaphragms 24, 34, 44 and to move these diaphragms against the respective valve seats to seal the apertures 21, 31, 41 when such pressure exceeds atmospheric pressure and the pressure of fuel.

The open outer e'nds of the cylindrical portions 30a, 40a are respectively provided with radially outwardly extending flanges 51, 50 which are surrounded by a clamping device including a slotted clamping ring 53 and a detachable locking member 54 which engages the slotted portion of the ring 53. A sealing washer 52 is compressed between the flanges 50, 51 and extends into the interior of the channel-shaped clamping ring 53 to prevent uncontrolled communication of air between the surrounding atmosphere and the-interior of the valve housing. As best shown in FIG. 2, the innermost portion of the sealing washer 52 serves to clamp two radially outwardly extending ange- like portions 35, 45 which are respectively integral with the disks 32, 42 so that these disks are positively held at a requisite distance from the respective valve seats 30, 40.

The disk 22 is held in position by a second portion of the disk 42 including a series of inclined radially inwardly extending elastic projections or lugs 46. Since one of the air admitting valves (e.g., the one including the seat 40, the disk 42 and the diaphragm 44) constitutes an optional feature of my invention, the disk 22 may be held in position by lugs provided on the disk 32 or in another suitable way. The disk 22 comprises a radially extending flange 25 which overlies a shoulder 20b provided at the inner side of the cylindrical portion 20a, see FIG. 2, and the lugs 46 are dimensioned in such a way that they press the v ange 25 against the shoulder 20b. The disk 22 further comprises a centrally located tubular extension or nipple 26 which is spacedly surrounded by and extends into the nipple 18 toward but somewhat short of the intake end of the mixer tube 11. There is a smooth arcuate transition between the flat portion of the disk 22 and the nipple 26. The fuel enters between the nipples 18 and 26 whereas the air enters through the nipple 26 so that the two fluids are mixed in the tube 11 which is of importance because the possibility that the mixture would explode in the interior of the valve housing is very remote. In the position of FIG. 2, the diaphragm 34 permits air to enter through the apertures 31 and to ow along the upper side of the diaphragm 34 toward and into the nipple 26 to be admitted into the mixer tube 11. The diaphragm 44 prevents entry of air through the apertures 41, and the diaphragm 24 prevents entry of fuel through the apertures 21. When a mixture which is admitted to the combustion chamber 10 is ignited by a spark plug or by Contact with the hot wall of the combustion chamber, a pressure wave travels not only into the resonance duct but also into the interior of the valve housing to move the diaphragms 24, 34, 44 against the respective valve seats 20, 30, 40 and to thus prevent entry of air or fuel by simultaneously preventing escape of combustion products into the surrounding atmosphere or into a fuel supply conduit. Each such pressure wave is followed by suction wave which is felt in the interior of the valve housing so that the diaphragms 24, 34, 44 are drawn against the respective disks 22, 32, 42 and allow air and fuel to enter the valve assembly. The air then ows into the compartments accommodating the diaphragms 34, 44 and thence into and through the nipple 26. The fuel flows through the annular gap between the nipples 18 and 26 and is admixed to air which iiows through the nipple 26.

The apertures 21 in the valve seat 20 may communicate directly with an annular manifold (not shown) provided at the discharge end of a fuel supply conduit and surrounding the apertures 21 or, alternatively, these apertures 21 may receive fuel through a sound absorbing chamber 60 whose annular casing surrounds portions of the base 16 and mixer tube 11. This chamber 60 constitutes a sound absorbing portion of the fuel supply conduit which includes a nozzle 61 communicating with the annular internal space of the chamber 60. The chamber 60 and the valve assembly 15 preferably form a unitary attachment which may be secured to or disconnected from the mixer tube 11. The upper shell 62 of the chamber 60 surrounds the outer side of the valve seat 20 and is press-fitted or otherwise secured on the cylindrical portion 20a. The other shell 62a of the chamber 60 is secured to an internally threaded sleeve 63 which is press-fitted or otherwise secured on the nipple 18 and which meshes with a second sleeve 65 provided on the mixer tube 11. Thus, the annular internal space of the sound absorbing chamber 60 is surrounded by the parts 62, 62a, 63 which together form the casing of this chamber. The intermeshing portions of the sleeves 63, 65 are shown at 66 and one of these sleeves is provided with an annular recess which receives an annular gasket 67. If the operator desires to separate the attachment including the chamber 60 and the valve assembly A15 from the pulse jet burner, he merely unscrews the sleeve 63 from the sleeve 65, and the chamber 6@ may be separated from the valve assembly 15 by withdrawing the parts 18, 20a from the parts 62, 63. The valve assembly 15 must be removed from time to time for the purpose of cleaning.

The provision of a sound absorbing chamber 60 which is an element of the fuel supply conduit and whose annular internal space surrounds at least a portion of the mixer tube lll'constitutes an optional feature of my invention, especially since the valve housing 16, 17 by itself acts as a sound absorbing body which is located in the path of air and fuel flowing into the mixer tube 11. As explained hereinabove, this chamber 60 may be omitted if the nozzle 61 of the fuel supply conduit is replaced by or assumes the form of a manifold which delivers fuel directly to the apertures 21. Also, the sound absorbing chamber 6() may be provided in the fuel supply conduit at a distance from the mixer tube 11 without departing from the spirit of my invention. In such construction, the nipple 18 is screwed onto or is otherwise detachably secured to the mixer tube 11. If one of the air admitting valves is capable of delivering sufficient quantities of air or oxygen, the other air admitting valve may be dispensed with.

In the embodiment of FIGS. 1 and 2, the pulse jet burner serves to heat water or another fluid medium which is caused to flow through a heating pipe 70. This pipe is convoluted around the mixer tube 11 and around the combustion chamber 10.

The combustion chamber may be subdivided into two or more smaller chambers, and each such smaller chamber may receive fuel and oxygen from a separate valve assembly or, alternatively, a single valve assembly may admit fuel and oxygen into two or more combustion chambers. Since the inner sleeve 65 forms part of the mixer tube 11, the discharge end of the inner nipple 26 actually extends into the intake end of the tube 11 to prevent any mixing of fuel and oxygen in the valve housing. This will be readily understood since, when the valve 20, 22, 24 admits fuel from the internal space of the sound absorbing housing 60, the diaphragm 24 seals the openings 23 so that the fuel must liow between the nipples 18, 26 and into the mixer tube. In other words, the construction of my improved valve assembly is preferably such that the paths for fuel and oxygen cannot merge in the valve housing 16, 17 but only in the mixer tube, i.e., in a part of the combustion chamber 10.

An important advantage of the feature that the sound absorbing chamber 66 of the fuel supply conduit surrounds at least a portion of the mixer tube 11 is that the fuel will exchange heat with the products of combustion prior to its entry into the combustion chamber. This results in an expansion and in increased kinematic tenacity of the fuel. Such characteristics of the fuel are of considerable advantage in pulse jet burners which utilize a slowly reacting fuel because the operation of the pulse jet burner may be normalized shortly after the burner is started. When the burner is started, the admission of fuel is automatically adjusted in such a way that the mixture of fuel and oxygen is fat, i.e., that the ratio of A said valve assembly fuel to air is equal to or slightly less than 1:1. Such fat mixture will react rather rapidly even though the combustion chamber 10 is still cold and the explosions will produce rather strong detonations. Also, such fa-t mixture is ready to be ignited at a point close to the intake end of the mixer tube 11 so that this tube is heated very rapidly and its temperature rises to normal operating temperature within a very short interval of time. The tube 11 then exchanges heat with the fuel in the sound absorbing chamber 60 so that the fuel expands and the mixture of such fuel with 4air is leaner \=l.1 to 1.2) because a hot mixer tube will preheat only the fuel but not the air. Such leaner mixture will travel deeper into the mixer tube or into the combustion chamber proper so that the ignition takes place at a point which is more distant from the valve assembly. This is of considerable advantage because the valve assembly is not overheated and remains operative for extended periods of time. In other words, and as long as the stroke of the fuel admitting valve member 24 remains unchanged, the percentage of fuel in the mixture which is admitted into the mixer tube 11 will be regulated in a fully automatic way starting with a fat mixture at the outset of the oper-ation and continuing with a leaner mixture when the combustion chamber is heated up to normal operating temperature at which the mixture will be ignited without a spark plug or a similar igniter device. The valve assembly of the present invention is particularly suited for delivering blast furnace gas and similar types of slowly reacting fuels.

Without further analysis, the foregoing will so fully reveal .the gist of the present -invention that others can, by applying current knowledge, readily adapt it for various applications ywithout omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic and specic aspects of this invention and, therefore, such adaptations should and are -intended to Ibe comprehended within the meaning and range of equivalence of the following claims.

What is `claimed as new and desired to be secured by Letters Patent is:

1. In a pulse jet b-urner, in combination, a combustion -chamber including a mixer tube having an intake end;

a valve assembly including rst and second valve means for respectively admitting fuel and air to the intake end of said mixer tube, each of said valve means comprising `an `apertured seat and said valve assembly including an apert'ured wall portion adjacent to said intake end and constituting the valve seat of said rst valve means; and a fuel supply `conduit comprising -an lannular sound absorbing chamber secured to said valve assembly and surrounding at least a portion of said mixer tube, said ksound absorbing chamber being adjacent to said apertured wall portion so that fuel flowing through said sound absorbing chamber may be delivered to said intake end by flowing through said iapertured wall portion.

2. A combination as set forth in claim 1, wherein comprises a substantially box-shaped housing having two lapentured wall portions which respectively constitute the valve seats of said valve means, each of said valve means further comprising a stop spaced `from the respective seat .and ya valve member reciprocable between `the stop and the respective seat, lone of said stops having a first portion secured to said valve housing and :a second portion engaging the other st-op to hold the same in requisite position with reference .to the respective valve seat.

3. A combination -as set Aforth in claim 2, wherein said valve housing includes two substantially cup-shaped members each of which comprises a flange, and clamping `means connecting the flanges Iof said cup-shaped members to each other, said first portion of said one st-op being received between said flanges and said second portion of said one stop comprising at least one elastic projection which engages `said .other stop.

d. A combination as set forth in claim 1, wherein said irst valve means comprises a stop spaced from the respective valve seat and a valve member movable between said stop and Ithe respective valve seat, said stop comprising a tubular extension .projecting iat least to the intake end of said mixertube, said first valve means being arranged to admit fuel around said extension and said second valve means being arranged to admit air through said extension so that `the `fuel and air form a mixture in' the interior of said mixer tube.

5. A combination las set forth in claim 1, wherein said valve assembly comprises .a substantially box-shaped valve housing and wherein said valve housing comprises a base member including said Wall portion and secured to said mixer tube, and a cover member connected with said base member and including a wall portion which constitutes the valve seat of said second valve means.

6. A combination as set forth in claim further comprising additional air admitting valve means having an apertured valve seat, said base member comprising a second wall portion surrounding the valve seat of said iirst valve means and constituting the valve seat of said additional air admitting valve means.

7. A combination as set forth in claim 6, wherein said second valve means further comprises a stop located in said housing and spaced from `the respective valve seat, and a valve member movable between said stop and the valve seat of said second valve means, said base member and said cover member being provided with radial anges, said housing comprising clamping means connecting said anges .to each other, and said stop having a portion received between said iianges.

l8. A combination as set forth in claim 1, for admitting oxygen and slowly reacting fuel to said combustion chamber wherein said valve assembly comprises a first and a second valve each including a substantially cupped valve seat having a bottom wall provided with a plurality of apertures, an annular stop located between said valve seats in the proximity of one thereof and having a plurality olf openings, and an annular valve member movable between said stop and the respective valve seat so as to respectively seal the apertures `and the openings in the corresponding valve; and means connecting said valve seats with each other so that said seats Itogether form a box-shaped housing, one of said bottom walls having a tubular extension arranged to communicate with said combustion chamber so that pressure iand suction waves developing in said chamber when the burner is in opera- Ition will be felt in said housing whereby said valve members are respec-tively moved into `sealing engagement with the seats and with the stops of the corresponding valves.

9. A combination as set forth in claim 1, wherein said valve -assembly comprises a rst and a second valve each including a valve seat having at least one aperture, a-

stop spaced from the respective valve seat and having at least one open-ing, and a valve member movable between the valve seat and the stop of the respective valve to alternatively seal said aperture .and said opening, and means connecting said valves to each other so that said seats together form =a housing and that said stops are disposed between said seats, one of said seats comprising a t-ubular portion arranged to be connected with said combustion chamber so that pressure and suction waves which develop in said chamber when the burner is in operation will be felt in said housing whereby the valve members are respectively moved into sealing engagement with the seats and with the stops of the corresponding valves, said fuel supply conduit comprising a portion communicating with the aperture of one of said valve seats so that `fuel delivered by said supply conduit may liow into said housing and around said extension when the respective valve member is moved away from said one seat.

10. A combination as set forth in claim 9, wherein said annular chamber is outwardly adjacent to and surrounds at least a portion of said one valve seat.

11. A combination as set forth in claim 1, for admitting oxygen and slowly reacting fuel to said combustion chamber wherein said valve `assembly comprises a first and a second valve each including a substantially cupped valve seat having a bottom wall provided with a plurality of apertures, an annular stop located between said valve seats in the proximity of one thereof and having a plurality of openings, and an annular elastic diaphragm movable between said stopand the respective valve seat so as to respectively seal the apertures and the openings in the corresponding valve; and means connecting said valve seats with each other so that said seats together form a box-shaped housing, one of said bottom walls having a tubular extension `arranged to communicate with said combustion chamber so that pressure and suction waves developing in said chamber when the burner is in operation will be felt in said housing whereby said diaphragms are respectively moved into sealing engagement with the seats and with the stops of the corresponding valves.

1'2. In `a pulse jet burner, in combination, a combustion chamber having an intake end; a valve assembly comprising a lirst and a second valve respectively arranged to deliver fuel and oxygen to said intake end, said first valve comprising an apertured seat surrounding said intake end and having a tubular extension substantially coaxial with and terminating close to said intake end, an annular stop adjacent to a tirst side of said valve seat which faces away from said intake end and having at least one opening therein, said stop further having a tubular extension surrounded by said first-mentioned extension so that said extensions together form an annular gap which communicates with said intake end, and an annular diaphragm disposed between said valve seat and said stop and alternatively reciprocable into sealing engagement therewith, said second valve comprising an apertured.

valve seat having an outer side surrounded by the atmosphere and an inner side, an annular stop adjacent to said last mentioned valve seat and having at least one opening therein, and an annular diaphrgam received between the valve seat and the stop of said second valve and movable alternatively into sealing engagement therewith; and a fuel supply conduit comprising a portion surrounding a second side of said first mentioned valve seat which is nearer to said intake end so that fuel delivered by said conduit may enter said first valve to ow through said annular gap and into said combustion chamber when the pressure of fuel in said conduit exceeds the pressure at the tirst side of said iirst mentioned valve seat.

13. In a pulse jet burner, in combination, a combustion chamber having an intake end; a valve assembly comprising `a first and a second valve respectively arranged to deliver fuel and oxygen to said intake end, said first valve comprising an apertured seat surrounding said intake end and having a tubular extension substantially coaxial with and terminating close to said intake end, an annular stop adjacent to `a first side of said valve seat which faces away from said intake end and having at least one opening therein, said stop further having a tubular extension surrounded by said first mentioned extension so that said extensions together form an annular gap which :communicates with said intake end, yand an annular diaphragm disposed between said valve seat and said stop and alternatively reciprocable into sealing engagement therewith, said second valve comprising an apertured valve seat having an outer side surrounded by the atmosphere and an inner side, an annular stop adjacent to said last mentioned valve seat and having at least one opening therein, and an annular diaphragm received between the valve seat and the stop of said second valve and movable alternatively into sealing engagement therewith; and -a fuel supply conduit comprising a sound absorbing chamber surrounding a second side of said first mentioned valve seat which is nearer to said intake end so that fuel delivered by said conduit may enter said first valve to flow through said annular gap and into said combustion chamber when the pressure of fuel in said conduit exceeds the pressure at the irst side of said first mentioned valve seat, said rsound absorbing chamber surrounding a portion of and being detachably secured to said valve assembly and to said `combustion chamber so that fuel owing through said sound absorbing chamber exchanges heat with said combustion chamber when the pulse jet burner is in operation.

References Cited by the Examiner UNITED STATES PATENTS FREDERICK L. MATTESON, JR., Primary Examiner. MEYER PERLIN, Examiner.

10 E. G. FAVORS, Assistant Examiner.

Claims (1)

1. IN A PULSE JET BURNER, IN COMBINATION, A COMBUSTION CHAMBER INCLUDING A MIXER TUBE HAVING AN INTAKE END; A VALVE ASSEMBLY INCLUDING FIRST AND SECOND VALVE MEANS FOR RESPECTIVELY ADMITTING FUEL AND AIR TO THE INTAKE END OF SAID MIXER TUBE, EACH OF SAID VALVE MEANS COMPRISING AN APERTURED SEAT AND SAID VALVE ASSEMBLY INCLUDING AN APERTURED WALL PORTION ADJACENT TO SAID INTAKE END AND CONSTITUTING THE VALVE SEAT OF SAID FIRST VALVE MEANS; AND A FUEL SUPPLY CONDUIT COMPRISING AN ANNULAR SOUND ABSORBING CHAMBER SECURED TO SAID VALVE ASSEMBLY AND SURROUNDING AT LEAST A PORTION OF SAID MIXER TUBE, SAID SOUND ABSORBING CHAMBER BEING ADJACENT TO SAID APERTURED WALL PORTION SO THAT FUEL FLOWING THROUGH SAID SOUND ABSORBING CHAMBER MAY BE DELIVERED TO SAID INTAKE END BY FLOWING THROUGH SAID APERTURED WALL PORTION.

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