US3028908A - Fuel burning system having an improved ignition arrangement - Google Patents

Description

April 10, 1962 G. BROLA 3,028,908

FUEL BURNING SYSTEM HAVING AN IMPROVED IGNITION ARRANGEMENT G. BROLA April 10, 1962 FUEL BURNING SYSTEM HAVING AN IMPROVED IGNITION ARRANGEMENT 2 Sheets-Sheet 2 Filed Jan. 20, 1959 VA wvm m, m

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United States Patent G 3,028,908 FUEL BURNDJG SYSTEM HAVING AN IMPROVED IGNITIG'N ARRANGEMENT Gabriel Brola, Bourg-ia-Reine, France, assignor to Societe Anonyme: Generale Therruique Procedes Brola, La Pre Saint-Gervais, France Filed Jan. 20, 1959, Ser. No. 787,932

Claims priority, application France Jan. 22, 1958 5 Claims. (Cl. 158-28) This invention relates to fuel burning systems and its general object is to provide an improved ignition arrangement therefor whereby starting the system into operation even after a prolonged idle period will be rendered simpler, more practical and more reliable than heretofore, and .whereby such starting can be efiected in an automatic or semi-automatic manner.

The invention is more especially, though not exclusive- 1y, applicable to fuel burning systems of the type in which a rotatable fuel burner element is adapted to have liquid fuel delivered axially thereto so that, by the action of centrifugal force in operation, a continuous uniform film of fuel is formed over an inner surface of the revolving burner element. Combustion air is delivered to the combustion zone adjacent the burner element, preferably by an air-blower which is rotatably driven simultaneously with the rotating burner so that a stable, steady, flame front is established in said combustion zone, primarily through surface combustion of said fuel film. The delivery of fuel to the burner is effected by a fuel pump which is preferably also driven from the same motor that drives the rotating burner element and the air blower; in one embodiment of such systems the revolving burner element and the air-blower fan or impeller are secured on a common shaft which likewise carries the rotor of an electric motor energization of which will rotate said shaft, and the fuel pump, e.g. a diaphragm pump, is driven from an eccentric or cam secured on the end of the shaft remote from the burner element. Fuel discharged by the pump is delivered into the revolving burner element by way of an axial duct extending through said common drive shaft.

Certain difficulties have been encountered in an adaptation of such rotary burner systems to automatic operation in connection with the initial ignition thereof, because once the burner element has started to revolve the continuous film that immediately forms as mentioned above, while being eminently well-suited for steady combustion, will not ignite easily. It is a specific object of this invention to overcome such difficulties by the provision of an ignition arrangement that will be reliably operable in an automatic or semi-automatic manner. For this purpose there is provided, according to the invention, an arrangement whereby during normal operation of the burner a metered amount of fuel is stored in an accumulator chamber interposed in the fuel pump discharge line. On termination of an operating period of the system, this amount of fuel is entrapped and placed under a predetermined high pressure. Thereafter, on resumption of operation of the burner at some later time, the entrapped volume of fuel is released and allowed to be discharged by the pressure under which it was stored into the combustion zone, this being done a short time before the burner is started in operation, there to be ignited by a suitable heating element, such as a resistance coil, provided adjacent the combustion zone, and which was brought to a suitable igniting temperature a short time before release of the metered amount of fuel. A pilot flame is thus produced and the system can then be started in normal operation whereupon the fuel delivered to the burner by the pump will be ignited by said flame.

Preferably an annular recess is provided iu'thc casing 3,028,908 Patented, Apr. 10, 1962 surrounding the burner element for receiving the metered amount of fuel, which recess receives a resistance coil constituting the heater element. The pilot flame will endure so long as the metered amount of fuel discharge into this cavity has not been burned up.

Where the invention is applied to a rotary-burner system of the type specified above, the fuel pump is desirably a diaphragm pump the discharge-outlet of which is connected by way of a check-valve to an inlet of the afore mentioned accumulator chamber. Means, such as springloaded diaphragm, are provided for limiting the pressure in said accumulator chamber to a prescribed value, and the outlet of said chamber is connected by way of a selectively operable shut-off valve, for example, a solenoidoperated valve, with a fuel delivery line which in turn is connected with the axial bore of the drive shaft through which the fuel is delivered to the burner element. In steady operation, an amount of fuel is permanently present in the accumulator chamber, and on termination of an operating period, when the fuel pump is brought to a stop, this body of fuel is entrapped in the chamber by closure of the shut-off valve, which closure is preferably effected automatically by deenergization of the valve-op er'ating solenoid simultaneously with the deenergization of the electric motor driving the pump and other components of the system. This body of fuel which is prevented from escaping out of the chamber on one side by the check-valve between the chamber and the pump and on the other side by the shut-off valve, is thus entrapped under a pressure that is determined by the loading of the accumulator diaphragm. When the system is to be started, opening the shut-off valve manually or automatically will then discharge this entrapped fuel under the afore-rnentioned pressure into the burner ignition recess.

The above and further objects, features and advantages of the invention will appear clearly from the ensuing disclosure which relates to a preferred embodiment of the invention and to a modification thereof, as applied to a rotary burner system of the general type specified above. In the accompanying drawings: a V

FIG. 1 is a diagrammatic view of a burner system in accordance with one embodiment of the-invention; and

FIG. 2 is'a similar showing relating to a modified embodiment.

As illustrated in FIG. 1, a rotary burner unit of the afore-specified type is shown in simplified form as comprising a casing 1 including an extension 2 constituting a tubular diffusor. Projecting axially into the" casing 1 is a shaft 5 journalled for rotation in suitable bearings, not shown. Secured upon an end portion of the shaft within an intermediate section of the housing 1 is a flared cuplike burner element 3 over the inner surface of which a film of fuel is adapted to form in operation as presently described. Keyed on shaft 5 in a foremost section of the casing 1 ahead of the burner element 3 is a vaned fan rotor 4 serving to blow combustion air for mixing with said fuel, and further keyed on the shaft ahead of the fan rotor and outside of the casing 1 is the wound or otherwise conventionally constructed rotor 6a of an electric motor 6, cooperating with field winding means 6b stationarily mounted in surrounding relation to the rotor 6a. Energization of stator field winding 6b is effected through circuit means consisting of conductors 6c and 6d extending from supply lines L and L and having a switch 6e interposed therein. Energization of field windings 6b by closing of switch 62 will impart rotation to the rotor 6a and hence to the shaft 5 with all of the components fixedly carried thereby.

Liquid fuel is supplied into burner element 3 by way of an axialduct formed through the shaft 5, the end of said duct at the extremity remote from the burner element being connected by a suitable fuel delivery line 15', diagrammatically shown as a chain-like connection, with a regulator valve chamber 20 supplied with fuel through means later described from a fuel pump 7, which is driven from the shaft 5.

The fuel pump 7 in the embodiment shown is a diaphragm pump and comprises a two-part casing between the parts of which a diaphragm 8 is clamped. Projecting from one side of the diaphragm towards the shaft but somewhat off-center with respect to the latter is a driver shank 9 while acting on the opposite side of the diaphragm is a loading spring 10 the bias of which is adjusta ble by means of a set screw 11. Secured to the end of the shaft 5 adjacent the pump is a driver cam, such as the slanted disc 12 illustrated, which is engaged by the shank 9 so that rotation of the shaft 5 will reciprocate said shank and thereby reciprocate the diaphragm 8. The pump chamber defined in the pump casing 7 on one side of the diaphragm is connected with a fuel supply line 14 having a check-valve 13 interposed therein, and also is connected with a fuel delivery line 15. Thus, on rotation of shaft 5 by means of electric motor 6, the pump will act to discharge fuel from the supply line 14 into the delivery line 15.

The delivery line 15 connects with the chamber of a fuel accumulator 17 by way of a check-valve 16 preventing backfiow of the fuel towards the pump. The accumulator 17 has one side of its chamber defined by a diaphragm 22 which is loaded by a spring 23 adjustably biassed by means of a set screw 24. A fuel delivery line 15a extends from the accumulator chamber 17 into the chamber of a solenoid-operated valve 18, the valve member therein being normally unseated to permit fuel fiow so long as the solenoid 19 is energized. A further delivery line 15b extends from the valve chamber 18 into the regulator valve chamber 20, the valve member of which is controlled in response to a selected parameter, such as temperature, or pressure, for which latter purpose an aneroid capsule 21 is illustrated as controlling the valve member of regulator valve 20. As previously indicated the fuel delivery line 15' connecting with the duct in shaft 5 extends from regulator valve chamber 20.

In normal operation solenoid 19 is energized by closing of switch 190 so that valve 18 is open and it is assumed that the value of the controlling parameter such as pressure is such that the valve 20 is open also. On energization of the field windings of motor 6 by closing of switch 6e the shaft 5 is rotated and cam 12 imparts reciprocation to shank 9 and to the diaphragm 7 of the fuel pump. Normally the pump then acts to draw in fuel from the supply line 14 through check-valve 13 and to discharge it into line 15 and through check-valve 16, accumulator 17, line 15a, valve 18, line 15b, valve 20, delivery line 15' and the axial duct through shaft 5 into the cup-like burner element 3. It will be noted however that should the pump discharge pressure increase beyond a predetermined upper limit as determined by the relative settings of bias-adjusting screws 11 and 24 loading the pump and accumulator diaphragms, the fuel pressure acting on the active side of pump diaphragm 8 will be so high as to overcome the force of the spring 10 and thereby prevent the driver shank 9 from maintaining contact with the cam 12, whereupon the pump will deliver no more fuel. It is seen therefore that the arrangement shown provides for a substantially constant fuel pressure in the pressure accumulator 17. The said constant pressure can be controlled by action on set screw 11 as already indicated.

The fuel discharged into the cup-shaped burner element 3 is projected on to the inner surface of the latter by centrifugal force and forms over said surface a substantially continuous and uniform film of liquidfuel. In steady state operation combustion in the burner occurs primarily over the surface of this fuel film to provide a steady, stable, flame front. is supplied to this combustion zone by the action of blower 4. Further combustion may occur in front of the revolving burner element 3 and in the tubular diffuser 2. During such normal steady-state operation of the system the automatic regulator valve 20 serves to regulate the rate of delivery of fuel to the burner in response to variations in the selected controlling parameter, such as temperature or pressure.

When the burner is to be deactivated, switches 6e and are actuated to cut off energizing current both from the field windings 6b of motor 6 and from the solenoid 19. Solenoid valve 18 thereupon seats immediately to cut off fuel delivery to the burner, but even though the motor 6 is deenergized the shaft 5 with the burner components carried by it still continues to revolve for some time (e.g. a few seconds) due to inertia, so that fuel pump 7 continues to discharge fuel into the accumulator chamber 17. Since the outlet from this chamber is now sealed off by closure of valve 18 the pressure in the accumulator rises rapidly and on attaining the aforementioned limiting level determined by the relative settings of bias screws 11 and 24, such pressure acting on the pump diaphragm 7 overcomes the action of spring 10 as previously mentioned and the pump discharges no more fuel, even though the shaft 5 may still be revolving by inertia. Hence the pressure in the accumulator 17 becomes established at a predetermined value and an accurately metered amount of fuel is now entrapped under pressure in said accumulator chamber 17, between valves 16 and 18.

For ignition purposes the burner casing 1 includes an enlarged section 25 defining an internal annular groove or recess just beyond the outer end of the revolving burner member 3. An electric-resistance 26 is coiled in this enlarged area so as to surround the combustion zone in the burner being shielded therefrom by suitable heatresistant means not shown. The resistance is energized through a circuit made up of conductors 26a and 26b with a switch 26c interposed therein. To start up the burner system embodying the invention the procedure is as follows:

Power is first supplied to the resistance 26 by closing switch 26c. When this has been thoroughly heated, power is applied through conductors 19a, 19b to the solenoid 19 by closing switch 190 to unseat the valve 18 or the valve may be opened manually. The metered amount of fuel entrapped within the accumulator chamber 17 at the end of the preceding operating period of the system is now discharged due to its storage pressure through line 15a, valve 18, line 15b, valve 20, line 15' and the shaft duct into the burner element 3 which is at this time stationary. This fuel flows down into the groove 25 in the easing into close proximity to the heated resistance 26 and is thereby ignited. A pilot flame is thus produced near the outer end of the burner member 3.

Power is now applied through conductors 6c, 6d to the field of motor 6 by closing switch 6e so that shaft 5 is set into rotation together with the components carried thereby. Fuel and air are now normally supplied to the revolving burner element 3 and the fuel-air mixture is ignited by contact with the pilot flame. The resistance 26 is now deenergized by opening switch 26c. The pilot flame continues to burn for a period of time determined by the amount of fuel initially discharged into the groove 25 as determined in turn by the setting of screw 24.

The modified embodiment of the invention illustrated in FIG. 2 differs from the embodiment just described only in the construction and arrangement of the fuel pump 7 and the accumulator 17 as well as the solenoid-operated valve 18-19. A majority of the components have been designated in this embodiment by the same reference numerals as those used for the corresponding components in the first embodiment.

The fuel pump 7 in this construction is provided with two spaced diaphragms 8a and 8b interconnected by a rigid spacer 28. The diaphragms are of unequal effective diameters, so that on bodily reciprocation of both diaphragms the volume of the chamber 27 defined between them is cyclically varied. Such bodily reciprocation is effected by the rotating shaft 5 acting by way of an eccentric member 12 which, through a ball bearing, engages a shank 9 projecting from the outer diaphragm 8b. It will of course be understood that instead of the eccentric and ball bearing arrangement, a slanting cam similar to that shown in FIG. 1 might also be used in this embodiment. The ball bearing serves to minimize friction and Wear.

In the embodiment shown in FIG. 2 the pressure accumulator 17 and solenoid-operated valve 18 are combined into a single unit. As shown, the fuel delivery line 15 from the diaphragm pump connects with an upper chamber in accumulator casing 17, defined above the diaphragm 22. The solenoid operated valve comprises a valve member 31 which controls the connection from the top of said chamber with the valve chamber 18 from whence a fuel delivery line 15b extends towards the automatic regulating valve chamber 20 which may be similar to that shown in FIG. 1. The diaphragm 22 is urged in a downward direction by the compression spring 33 which, therefore, aids the pressure of the fuel on the diaphragm. From the under side of the diaphragm 22 extends a shank 34 constitutingor carrying a solenoid core which cooperates with the solenoid 19 in such a manner that on energization of the solenoid by closing of the switch 19:: the shank 34 is urged upwardly in a direction to unseat the valve member 31 in opposition to the combined fuel pressure and loading of spring 33. The general operation of this system is similar to the system in FIG. 1.

When burner operation is arrested energizing current is cut off both to the drive motor 6 and from solenoid 19 by opening switches fie and 190, whereupon valve member 31 is immediately seated to seal off the delivery of fuel to the burner. The shaft 5 however does not come to an immediate stop but continues to revolve for some time due to the kinetic energy of the rotating parts, so that pump 7 continues to deliver fuel, which, through checkvalve 16, charges the accumulator 17 building up pressure therein." On saidpressure exceeding a predetermined value depending on adjustment of the diaphragm biassing springs in the pump and accumulator, the diaphragms 8a, 8b of the pump are bodily displaced upwards (as shown) and the driver shank 9 is lifted out of engagement with the ecentric member 12 so that the pump is no longer driven, even though the shaft 5 may still continue to revolve for a time. This results in entrapping, within the accumulator chamber, a predetermined quantity of fuel at a predetermined pressure. It will be noted that in this construction the valve 31 serving to entrap the fuel in the accumulator during the idle periods of the system is applied against its seat under a pressure which depends both on the load of spring 33 and on the pressure head of the fuel. This may be especially desirable in installations where the fuel supply is provided in the form of an elevated reservoir since the pressure applying the valve 31 against its seat will increase proportionately with the reservoir pressure tending to force the fuel out of the accumulator, thus averting any danger of flooding the burner while the latter is idle.

To start up the burner, switch 260 is closed so that energizing current is first applied to igniter resistance 26 to heat it, then solenoid 19 is energized in turn by closing switch 190, whereupon the valve 31 is moved to open position and the metered amount of fuel entrapped in the accumulator is discharged by the resulting upward movement of diaphragm 22 under high pressure into the burner; the operation then proceeds as described with reference to FIG. 1.

It will be understood that various changes may be made in the forms of embodiment shown and described, as by 6 interchanging some of the features between both embodiments, as well as substituting equivalent components for some of the components shown.

' What I claim is:

1. In a fuel burning system, the combination of means defining a combustion zone including a rotary cup-shaped burner element, means for delivering air to said combustion zone, motor means connected to said air delivering means to operate the latter and also connected to said burner element for effecting rotation thereof, an electri cally energizable fuel igniting element adjacent said combustion zone, and means for delivering fuel to said combustion zone including pumping means operable by said motor means, conduit means opening in said burner element for conducting fuel from said pumping means to said combustion zone, a fuel accumulator interposed in said conduit means and being charged with fuel under a predetermined pressure during operation of said pumping means, means associated with said pumping means to interrupt the feeding of fuel from the latter to said ac cumulator when the fuel in the accumulator reaches said predetermined pressure, electrically operable shut-off valve means interposed in said conduit means between said accumulator and said combustion zone, check-valve means in said conduit means between saidaccumulator and said pumping means, energizing circuit means including-switch means for each of said motor means, said igniting element and said shut-off valve means, said switch means being selectively operable to'close said shut-off valve means upon termination of the operation of said motor means so that a metered quantity of fuel under said predetermined pressure is entrapped in said accumulator between said shut-off and check-valve means, and to open said shut-off valve means and energize said igniting element prior to the resumption of operation of said motor means so that said metered quantity of fuel is then discharged into said combustion zoneto be ignited by said fuel igniting element, and a tubular diffuser extending around'said burner element and axially beyond the latter, said diffuser having a circumferential groove with said igniting element disposed in said groove so that, when said metered quantity of fuel is discharged, the fuel enters the combustion zone through said burner element and drips from the latter into said groove for collection by the latter and contact with said igniting element.

2; In a fuel burning system, the combination as in claim 1; wherein said pumping means includes at least one membrane defining a wall of a pumping chamber, spring means acting on said membrane in the direction for decreasing the volume of said pumping chamber, an actuating rod extending from said membrance in said direction, and cam means driven by said motor means and loosely engageable by said rod for periodically moving the latter in the direction opposed to the action of said spring means; and wherein said means to interrupt the feeding of fuel from said pumping means includes a movable abutment adjustably loading said spring means so that said predetermined pressure overcomes the action of said spring means and holds said membrance in said opposed direction to disengage said rod from said cam means.

3. In a fuel burning system, the combination as in claim 2; wherein said pumping means includes a second membrane spaced from and movable with the first mentioned membrane so that said pumping chamber is defined between said first and second membranes, said first and second membranes having unequal areas so that the volume of said pumping chamber is decreased when said membranes are jointly moved by said spring means.

4. In a fuel burning system, the combination of means defining a combustion zone, fuel pumping means, motor means for operating said fuel pumping means, conduit means for conveying fuel from said pumping means to said combustion zone, a fuel accumulator interposed in said conduit means, a check valve interposed in said conduit means between said pumping means and fuel accumulator and permitting flow only in the direction toward the latter, said accumulator including a housing having a fixed wall with an opening therein defining a valve seat and communicating with the conduit means extending to said combustion zone, a diaphragm in said housing and disposed opposite said fixed wall, the conduit means from said pumping means opening into said housing between said diaphragm and said fixed wall so that the pressure of the fuel pumped into said housing tends to displace said diaphragm away from said fixed wall, spring means acting on said diaphragm to urge the latter away from said fixed wall, a valve stem fixed to said diaphragm and extending through said opening of the fixed wall, a valve on said stem moved against said valve seat to close said opening upon movement of said diaphragm away from said fixed wall by said spring means and the pressure of fuel in said housing, solenoid means connected to said diaphragm and operative, when energized, to move said diaphragm toward said fixed wall and thereby unseat said valve, circuit means including switch means for energizing said solenoid means and for operating said motor means, respectively, so that said solenoid means can be deenergized upon termination of the operation of said motor means to cause said valve to close said opening and thereby entrap a metered body of fuel in said accumw lator, and said solenoid means can be energized again prior to resumption of operation of said motor means to cause said diaphragm to forcibly discharge said metered body of fuel past the unseated valve and into said combustion zone, an electrically energizable igniting element adjacent said zone, and circuit means including switch means for energizing said igniting element prior to energizing of said solenoid means so that said igniting element is then adapted to contact the discharged fuel for igniting the latter.

5. In a fuel burning system, the combination of means defining a combustion zone including a rotary cup-shaped burner element, means for delivering air to said combustion zone, motor means connected to said delivering means to operate the latter and also connected to said burner element for effecting rotation thereof, an electrically energizable fuel igniting element adjacent said combustion zone, and means for delivering fuel to said combustion zone including pumping means operable by said motor means, conduit means opening in said burner element for conducting fuel from said pumping means to said combustion zone, a fuel accumulator interposed in said conduit means and being charged with fuel under a predetermined pressure during operation of said pumping means, means associated with said pumping means to interrupt the feeding of fuel from the latter to said accumulator when the fuel in the accumulator reaches said predetermined pressure, electrically operable shut-off valve means interposed in said conduit means between said accumulator and said combustion zone, check-valve means in said conduit means between said accumulator and said pumping means, energizing circuit means including switch means for each of said motor means, said igniting element and said shut-off valve means, said switch means being selectively operable to close said shut-off valve means upon termination of the operation of said motor means so that a metered quantity of fuel under said predetermined pressure is entrapped in said accumulator between said shut-off and check-valve means, and to open said shut-off valve means and energize said igniting element prior to the resumption of operation of said motor means so that said metered quantity of fuel is then discharged into said combustion zone to be ignited by said fuel igniting element, and means extending axially beyond said burner element and defining a channel at least in the lower portion thereof, which channel has said igniting element disposed therein so that, when said metered quantity of fuel is discharged, the fuel entering the combustion zone through said burner element drips from the latter into said channel for collection by the channel and ensured contact with said igniting element.

References Cited in the file of this patent UNITED STATES PATENTS 941,587 Putnam Nov. 30, 1909 1,881,939 Purdy Oct. 11, 1932 2,005,832 Vidalie June 25, 1935 2,064,750 Hurst Dec. 15, 1936 2,319,711 Van Almelo May 18, 1943 2,592,132 Fielden et al. Apr. 8, 1952 2,825,396 Greer et a1 Mar. 4, 1958

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