US3630652A

US3630652A - Liquid fuel burner system and fuel control

Info

Publication number: US3630652A
Application number: US754684A
Authority: US
Inventors: Warren D Nutten; Bernard C Phillips
Original assignee: Borg Warner Corp
Current assignee: TILLOTSON Ltd (TILLOSTSON") A CORP OF IRELAND; Borg Warner Corp
Priority date: 1968-08-22
Filing date: 1968-08-22
Publication date: 1971-12-28
Anticipated expiration: 1988-12-28

Abstract

1. A low-pressure oil burning unit comprising a burner head, a low-pressure aspirating nozzle mounted in and projected from said head, said nozzle having fuel and aspirating passages, said head having means defining a fuel passage in connection with said nozzle fuel passage, a compressor in connection with said head for delivering a high-velocity flow of air to and through said nozzle aspirating passage, a supply line in connection with said fuel passage incorporating therein a control regulator including a housing having an intermediately positioned diaphragm forming two chambers, one of which is vented to the atmosphere and the other of which has an inlet and an outlet positioned in the line of flow through said regulator, and means normally sealing said inlet operative to block the flow of fuel through said other chamber and its outlet and prevent its passage to said nozzle except on the occurrence of a high-velocity flow of air through the aspirating passage of said nozzle.

Description

United States Patent [72] Inventors Warren D. Nutten Grafton, Wis.; Bernard C. Phillips, Toledo, Ohio [21] App]. No. 754,684 [22] Filed Aug. 22, 1968 [45] Patented Dec. 28, 1971 [73] Assignee Borg-Warner Corporation Chicago, Ill.

[54] LIQUID FUEL BURNER SYSTEM AND FUEL CONTROL 1 Claim, 9 Drawing Figs.

[52] US. Cl. 431/253, 137/505.46,137/506, 431/350 [51] Int. Cl F23d 13/24 [50] Field of Search 137/549, 494, 505.46, 505.47, 506; 431/350, 253

[56] References Cited UNITED STATES PATENTS 1,615,406 1/1927 Replogle 137/549 X 2,362,352 11/1944 Buttner 137/549 X 2,416,267 2/1947 Landon 137/549 X Primary Examiner-Edward G. Favors Attorney-Harry O. Ernsberger CLAIM: 1. A low-pressure oil burning unit comprising a burner head, a low-pressure aspirating nozzle mounted in and projected from said head, said nozzle having fuel and aspirating passages, said head having means defining a fuel passage in connection with said nozzle fuel passage, a compressor in connection with said head for delivering a high-velocity flow of air to and through said nozzle aspirating passage, a supply line in connection with said fuel passage incorporating therein a control regulator including a housing having an intermediately positioned diaphragm forming two chambers, one of which is vented to the atmosphere and the other of which has an inlet and an outlet positioned in the line of flow through said regulator, and means normally sealing said inlet operative to block the flow of fuel through said other chamber and its outlet and prevent its passage to said nozzle except on the occurrence of a high-velocity flow of air through the aspirating passage of said nozzle.

PATENTED M82819?! SHEET 1 BF 3 INVENTORS WARREN 0. Mn TEN & BY BER/mm C. pH/LL/PS "L E? MW ATTORNEY LIQUID FUEL BURNER SYSTEM AND FUEL CONTROL This is a division of application Ser. No. 706,451, filed Feb. 19, 1968, now US. Pat. No. 3,428,406 which is a division of application Ser. No. 368,475, filed May 19, 1964, issued into U.S. Pat. No. 3,377,024.

This invention relates to a liquid fuel combustion burner system and control and more particularly to a fuel control for a combustion burner of a character wherein liquid hydrocarbon fuel is aspirated under the influence of a high-velocity airstream into a fueland air-mixing zone.

Liquid hydrocarbon fuels, such as fuel oils, have been used in fuel burners of a character wherein an airstream is utilized to aspirate fuel from a fuel bowl equipped with a float-controlled valve and supplied with liquid fuel from a fuel supply tank located above the burner whereby the fuel is elevated or lifted from the float or fuel bowl by reduced pressure or suction developed by an airstream and the liquid fuel mixed with the air to provide a combustible mixture. Arrangements of this character have been used in burners for salamanders and for similar uses.

In combustion burners of this character the fuel supply tank must necessarily be disposed above the float bowl because of lack of control of fuel feed for a fuel supply disposed below the burner. In such installations the fuel tank is disposed above the burner providing a gravity or pressure head of liquid fuel operative against the float-controlled valve arrangement. With such arrangement, the float control is subservient in a measure to variations in the level of the fuel in the float bowl resulting in variations in fuel delivery to the burner nozzle. As the fuel bowl must be vented, it presents a serious fire hazard and, furthermore, the fuel bowl must be maintained stationary and in an upright position in order to function.

The present invention embraces a method of controlling delivery of liquid fuel to a combustion burner from a fuel tank which includes establishing an airstream and flowing fuel from a flexible walled chamber to the combustion zone of the burner by aspiration set up by the airstream, normally biasing a fuel inlet valve in a fuel duct from a fuel supply to closed position, and opening the inlet valve by movement of the flexible wall under the influence of differential pressures to effect delivery of fuel to the burner nozzle.

The invention embraces a method of controlling delivery of liquid fuel to the combustion zone of a combustion burner involving the use of a pressure responsive member controlling a fuel inlet valve whereby fuel is delivered to the burner when differential pressures are developed of a magnitude affecting the member to overcome a biasing force normally closing the inlet valve whereby the said control is effective irrespective of whether the fuel supply is maintained above or below the combustion burner.

Another object of the invention resides in a control for liquid fuel delivered to a combustion burner wherein the control is influenced by differential pressure set up by an airstream into which the fuel is delivered and wherein means normally biasing a fuel inlet valve to closed position must be overcome by differential pressure before fuel is delivered to the combustion zone.

Another object of the invention resides in the provision of a pressure responsive arrangement for controlling delivery of liquid fuel into an airstream of a combustion burner wherein a diaphragm actuated by differential pressures controls a fuel inlet valve, the arrangement including means normally biasing the inlet valve closed whereby impairment of operating pressures or fracture of the diaphragm results in instant closure of the fuel inlet valve to thereby reduce the hazard of fire.

Another object of the invention resides in the provision of a differential pressure control of the delivery of fuel by aspiration to a combustion zone of a combustion burner which is effective irrespective of the relative position of the fuel tank with respect to the burner.

Another object of the invention is the provision of a pressure-responsive control system particularly usable for controlling delivery of liquid fuel to a mixing region of a combustion burner wherein the system includes dual pressureresponsive devices arranged in sequential relation and each provided with a diaphragm actuated fuel valve for controlling fuel flow under the influence of pressure responsive diaphragms providing protection against fire hazard and wherein impairment or failure of one device effectively interrupts fuel flow.

Another object of the invention is the provision of a pressure responsive control unit for connection between a fuel supply and a fuel delivery nozzle of a combustion burner wherein the unit is of compact construction embodying dual valves, each controlled independently by a pressure-responsive device, the valves being arranged in sequence and each provided with means effective to close an inlet valve upon failure or impairment of the pressure-responsive means.

Another object of the invention resides in a pressureresponsive control unit associated with or embodying an effective fuel filter for straining the fuel prior to its delivery through the unit to minimize the liability of foreign matter impairing the closing of the inlet valve or valves of the control unit.

Another object of the invention resides in a single control unit or dual units in sequential relation each embodying a pressure-responsive diaphragm arranged to be actuated by pressure of an airstream delivered to the combustion zone of the burner in combination with means for positively interrupting fuel flow from a supply upon failure of air pressure or impairment or fracture of a diaphragm.

Another object of the invention is the provision of a differential pressure actuated unit for controlling flow of liquid fuel to an aspirated nozzle of a combustion burner arranged to automatically interrupt fuel flow upon impairment or failure of aspiration at the burner nozzle.

Further objects and advantages are within the scope of this invention such as relate to the arrangement, operation and function of the related elements of the structure, to various details of construction and to combinations of parts, elements per se, and to economics of manufacture and numerous other features as will be apparent from a consideration of the specification and drawing of a fon'n of the invention, which may be preferred, in which:

FIG. 1 is a semischematic view, partly in section, of a liquid fuel feed and air mixing arrangement for a combustion burner embodying a form of differential pressure-actuated fuel flow control means of the invention;

FIG. 2 is a sectional view taken substantially on the line 2 2 of FIG. 1;

FIG. 3 is an elevational view of the fuel control means shown in FIG. 1;

FIG. 4 is a top plan view of the arrangement shown in FIG.

FIG. 5 is a sectional view taken substantially on the line 5- 5 of FIG. 4;

FIG. 6 is a schematic sectional view illustrating the components of the type of unit shown in FIG. 5;

FIG. 7 is a sectional view illustrating a liquid fuel flow control unit of the invention embodying one pressure-responsive means and control valve;

FIG. 8 is a top plan view, on a reduced scale, of the construction shown in FIG. 7, and

FIG. 9 is a fragmentary detail sectional view illustrating a fuel inlet valve and diaphragm control means therefor.

The method and apparatus of the invention are particularly adapted for controlling flow of liquid fuel to a fuel delivery nozzle of a combustion burner of a type wherein the fuel is aspirated into an airstream and the mixture ignited in a combustion zone of a burner, such as burners used in salamanders, oil-fired burners used with heating furnaces and the like.

Referring to the drawings in detail and initially to FIGS. 1 and 2, there is illustrated a burner construction which may be associated with a combustion chamber or zone defined by a member 10, a circular bracket 12 of conventional construction being employed for mounting the burner to the member 10. In the arrangement illustrated in FIG. 1, the burner is inelusive of a generally cylindrically shaped member 16 having a hollow sleeve portion 18, the forward end of the sleeve being secured by screws 14 to the bracket 12. Disposed at the rear of the member 16 is a vane type rotary pump comprising a housing 20 having an interior circular chamber 22. Rotatably mounted in the chamber 22 on an axis eccentric to the axis of the chamber 22 is a rotor 24 provided with radial slots 26 in which are disposed relatively slidable vanes 28. The rotor 24 is fixedly secured upon a shaft 30 of an electrically energizable motor 32.

The member 20 is provided with an opening or port 34 providing for the entrance of air into the pump chamber 22. The member 16 is provided with an outlet duct 36 which is in communication with the pump chamber 22 and through which air, which is compressed by rotation of the pump rotor 24, is delivered to a chamber 38 arranged axially in the member 16. Arranged axially of the chamber 38 is a fuel delivery nozzle 40 through which fuel is delivered into an ignition zone 42 defined by the sleeve 18, the burning mixture being delivered into a combustion zone or region 44.

In the embodiment illustrated, a member 46 surrounds the fuel delivery nozzle 40 and has its interior surface 47 of Venturi configuration providing a restricted zone or band 48 adjacent the outlet of the nozzle 40. In the embodiment illustrated, fuel is aspirated through the nozzle 40 by the velocity of the airstream passing through the annular restricted space 50 at the choke band of the Venturi which sets up a reduced or subatmospheric pressure at the nozzle outlet.

Fuel is supplied from a tank or receptacle 54 through a conduit or pipe 56, a manually operable valve 58 being provided in the conduit 56 for cutting off the fuel supply when desired. The conduit 56 conveys fuel to the inlet side of a pressure-actuated fuel control mechanism or unit 60 hereinafter described in detail. Fuel is conveyed from the outlet of the unit 60 through a fitting 61, pipe 62 and interconnecting channels 64 and 66 in member 16 to the nozzle 40 for delivery through the nozzle.

Fuel aspirated from the nozzle 40 is initially mixed with air delivered from the air pump chamber 22 flowing at substantial velocity through the annular space 50 of the Venturi, and additional air is mixed with the fuel through openings 68 formed in the sleeve portion 18 of the member 16 to provide the requisite amount of air for satisfactory combustion in zones 42 and 44.

Surrounding the burner construction and the motor 32 is a housing 70 of generally cylindrical shape which is secured to an annular bracket 72 mounted by the motor 32, screws 73 securing the housing to the bracket.

The forward portion of the housing 70 is flared inwardly and the terminal portion thereof secured to the sleeve 18 by screws 74. Mounted upon the rear end of the motor shaft 30 is an impeller or fan 76 which is rotated by the motor and provides a moving airstream along the exterior of the motor 32 and through the openings 68. A filter or screen 80 is secured to the rear end of the housing 70 for filtering the air moved by the impeller 76 and the air compressed in the pump chamber 22.

A spark plug 82 is threaded into an opening in the member 16, the spark plug being connected by a conductor 83 with an ignition coil or transformer 84 supplied with alternating current in a conventional manner. The conductor 83 extends through a rubber grommet 86 mounted in an opening in the wall of the housing 70. The spark plug ignites the mixture of liquid fuel and air in the zone 42 and the burning mixture enters the combustion zone 44 and is completely burned thereinv The pipe 62 extends through a grommet 65 mounted in an opening in the housing 70.

It is to be understood that other forms of air and fuel mixing arrangements may be used in lieu of the Venturi construction 47.

For example, a conventional type of fuel and air aspirating mixing nozzle may be employed. The burner arrangement described is of a character for burning conventional liquid hydrocarbon fuels such as fuel oils for conventional combustion burners.

One form of pressure actuated valve arrangement for controlling flow of liquid fuel to the burner is illustrated in FIGS. 3, 4 and 5 and a schematic sectional view of this construction is illustrated in FIG. 6. The control arrangement in this form embodies duel fuel flow control valves and dual pressure actuated diaphragms for controlling the valves. The control arrangement 60 is inclusive of a body member or housing 90 of generally cylindrical shape. The housing is formed with a substantially annular portion 91 defining a fuel chamber 98, a planar surface 92 of the annular portion providing a seat for an annular gasket 93, a flexible diaphragm 94 engaging the gasket 93 as shown in FIG. 5.

A circular cover plate 95 is secured to the body 90 by screws 96 threaded into suitable openings in the body 90. The diaphragm 94, which is of flexible impervious material forms a flexible wall of the fuel chamber 98. The central region of the cover 95 is recessed or shaped to provide a space or air chamber 99 to facilitate flexing movements of the diaphragm 94, the space 99 being vented to the atmosphere through a vent opening 100. The diaphragm is flanked at each side by relatively thin circular reinforcing plates 101 fashioned of thin metal or plastic material.

The diaphragm 94 and the reinforcing plates 101 are formed with aligned central openings to receive a shank of a rivet 102, the head 103 of the rivet extending into the fuel chamber 98. The diaphragm 94 may be fashioned of fabric impregnated or coated with synthetic rubber or may be formed of resinous material of a character that does not deteriorate on contact with hydrocarbon fuels. The housing 90 is provided with a boss portion 104 provided with a threaded inlet bore 105 to receive a fitting 106, shown in FIG. 1, for connecting the conduit 56 with the control unit 60. The threaded bore 105 in the boss 104 is connected with a duct or channel 107.

Referring particularly to FIGS. 4 and 5 and to the semischematic view of FIG. 6, the body 90 is provided with a threaded bore to accommodate a threaded sleeve or valve cage 109 in which is slidably disposed an inlet valve or valve member 110 provided with a cone-shaped valve portion 111 which seats in an annular seat member 112 mounted in the upper end of the valve cage 109. An annular sealing gasket 114 is disposed adjacent the inner end of the valve cage 109 to provide a seal. The body portion of the valve 110 is of polygonally shaped cross section, such as triangular or square shape, to facilitate flow ofliquid fuel past the valve.

Disposed in the chamber 98 is a lever 116 fulcrumed upon a pin or shaft 117 carried by the body 90. The long arm 118 of the lever is adapted to be engaged by the button or head 103 of the rivet 102, the short arm 120 of the lever being engageable with the valve member 110.

The lower end of the valve body is provided with a recess forming a tenon portion 121 and the short arm 120 of the lever is forked or bifurcated to straddle the tenon portion, the recess providing a head 122.

This construction provides a positive connection between the lever and the valve member so that upward movement of the diaphragm 94, as viewed in FIG. 5, effects counterclockwise movement of the lever 116 moving the valve portion 111 away from the seat 112 whereby fuel will flow from the inlet duct 107 through the port 115 in the valve seat 112 into the chamber 98. A resilient member or spring 124 arranged between a wall of the chamber 98 and the lever arm 118 exerts a force upon the lever normally biasing the inlet valve 111 toward the valve seat 112 to interrupt fuel flow into the chamber 98.

The semischematic sectional view of FIG. 6 particularly illustrates the fuel inlet and fuel filter construction. The housing 90 is provided with a bore having a threaded portion 128 which receives a threaded plug 130. The plug 130 is provided with an interior bore 131 in which is telescoped a cylindrically shaped screen or filter 132, the end of the screen being closed by a cup-shaped member 133. The plug 130 is provided with a counterbore 134 and a peripheral recess 135.

A plurality of circumferentially spaced radial openings 136 establish communication between the peripheral recess 135 and the counterbore 134. The peripheral recess 135 is in communication with the fuel inlet passage 107 shown in FIGS. 5 and 6 for conveying fuel to the port 115 adjacent the valve member 110.

The filter 132 illustrated herein is of fine mesh copper screen to filter foreign particles out of fuel, but it is to be understood that other types of filter may be used such as wool or other fibrous material.

The arrangement shown in FIGS. 3 through 6 is inclusive of a second valve construction arranged to be actuated by differential pressure set up by the airstream passing through the restricted passage 50 of the Venturi 47 shown in FIG. 1. The housing 90 is provided with a substantially annular portion 138 defining a second fuel chamber 150, an upper planar surface 140 of portion 138 forming a seat for gasket 151. Engaging the gasket 141 is a second diaphragm 142 of the same character as the diaphragm 94, the diaphragm 142 forming a wall of chamber 150. A second closure plate 144 engages the diaphragm 142 and is secured to the housing by screws 146 threaded into suitable openings in the housing 90.

The central region of the closure 144 is shaped to provide a space 148 to accommodate flexing movements of the diaphragm 142. The closure 144 is vented to the atmosphere by a vent opening 149. Disposed centrally of the diaphragm 142 is a rivet 152 which extends through reinforcing discs 1S3 arranged at each side of the diaphragm. Fulcrumed upon a pin 154 in chamber 150 is a second lever 156, one end of the lever being arranged to be engaged by a head 157 of the rivet 152.

The short arm of the lever is bifurcated to straddle a tenon 158 formed on a valve body 160, the latter being of the same character as the valve member 110. The valve member 160 is slidably mounted within a valve cage or guide means 162 threaded into a bore in the housing 90. Arranged in the cage 162 is an annular valve seat 164 providing a port 165 into which extends a cone-shaped valve portion 166 of the valve member 160 to control fuel flow through the port 165. A sealing gasket 168 is disposed at the end of the valve cage 162. The port 165 is in communication with the chamber 98 by a passage 170.

As shown in FIG. 6, the housing is provided with a threaded bore 172 providing an outlet which is adapted to accommodate the fitting 61 shown in FIG. 1. The bore 172 is in communication with the chamber 148 through interconnecting

channels

174 and 175. The lever 156 is biased in a direction to close the valve 166 by an expansive coil spring 159 in the same manner that the spring 124 biases the valve 111 toward closed position.

The operation of the control unit 60 with a burner arrangement as shown in FIG. 1 is as follows: The motor 32, d' ving the air pump rotor 24 and the impeller 76, is energized simultaneously with the energization of the transformer 84 to initiate a spark between the points of the ignition plug 82.

The operation or rotation of the pump rotor 24 develops air under pressure in the pump outlet passage 36 providing a high velocity airstream through the restricted passage or choke band 50 of the Venturi 47 developing a subatmospheric or reduced pressure at the region of the fuel delivery orifice or nozzle 40.

The subatmosphen'c pressure or aspiration developed at the burner nozzle is communicated through the channels 66, 64, the pipe 62 and fitting 61 is transmitted through the interconnecting

channels

174 and 175 to the chamber 150. Due to the differential pressures existent on opposite sides of the diaphragm 142, the atmospheric pressure in chamber 148 flexes the diaphragm 142 downwardly, as viewed in FIG. 5, to effect counterclockwise movement of the lever 156 about the fulcrum 154 through engagement of the button 157 on the diaphragm with the long arm of the lever 156.

The area of the diaphragm 142 is sufficient whereby the atmospheric pressure acting on the diaphragm, when subatmospheric pressure exists in the chamber 150, overcomes the biasing pressure of the spring 159 to effect counterclockwise movement of the lever 156, the lever 156 multiplying the force effective to open the valve 160. The short arm of the lever 156 withdraws the valve body upwardly to move the valve portion 166 out of engagement with the seat 164 to establish communication between the chamber 150 through the port and passage with the chamber 98 adjacent the diaphragm 94.

The areas of the

diaphragms

142 and 94 subject to differential pressures are substantially the same. When subatmospheric pressure is impressed in the chamber 98 by the opening of the valve 160, the diaphragm 94, as viewed in H0. 5 is flexed upwardly under the influence of atmospheric pressure in the space 99. This movement causes the lever 116 to be swung in a counterclockwise direction, the button 103 on the diaphragm being engaged with the arm 118 of the lever 116. In this manner, the reduced pressure existent in the chamber 150 is also existent in the chamber 98 when the valve 160 is in open or partially open position.

As the diaphragm 94 is flexed upwardly, the valve 110, connected with the short arm 120 of the lever 116, is moved downwardly moving the valve portion 111 out of the engagement with its seat 112 to open the port 115 and admit fuel into the chamber 98 from the tank 54 through the pipe 56, fitting 106, channel 107 to the interior of the plug 130, through the filter or screen 132 and passage 115 past the valve 111. As shown in FIG. 1, the fuel conveying tube 56 is connected with a manually operated valve 58, the latter being in normally open position to establish communication between the fuel tank and the tube 56.

As both

valves

110 and 160 are thus opened through the impression of subatmospheric pressures in the

chambers

150 and 98, fuel flows from the supply through the tube 56 into the inlet 105, through the filter screen 132 and passage 107, through the port 115, past the valve body 110, through the chamber 98, connecting channel 170, through the port 165, past the valve portion 166 and valve body 160, through the chamber 150, connecting channels 174 and and the outlet 172, fitting 61, tube 62 and channels 64 and 66 for discharge through the fuel delivery orifice 40 into the airstream moving through the restricted region of the Venturi 47.

Initial mixing of the fuel with air delivered from the pump chamber 22 of the air pump takes place in the region of the Venturi 47, and additional air provided by the rotating impeller 76 flows through the openings 68 and is mixed with the fuel and air delivered from the Venturi 47 to enhance more complete combustion, the burning gases moving through the sleeve 42 of burner construction shown in FIG. 1.

Through this arrangement fuel is aspirated from the nozzle 40 only when an airstream is moving at high velocity adjacent the fuel delivery orifice 40 and the burner is in operation. In event of failure of airflow through the Venturi, pressures are equalized at opposite sides of the

diaphragms

94 and 142 and the normal biasing pressures of the

springs

124 and 159 acting through their respective levers close both

valves

110 and 160.

The control unit illustrated in FIGS. 3 through 6 embodies several features which render the construction an effective control for a combustion burner where the fuel is aspirated into an airstream to provide a combustible mixture. From the standpoint of fire hazard, it is desirable that the valve seat 112 of the first inlet valve arrangement, that is, the valve arrangement first to receive fuel from the fuel line 56, be formed of metal and the valve body 110 be formed of metal. By fashioning the valve seat 112 of metal, the seat will not be impaired or subject to failure until the entire control unit is rendered ineffective by fire.

The valve seat 164 of the second valve arrangement in the unit may be fashioned of synthetic rubber or similar material or may be fashioned of metal. It is however desirable that the second valve seat 164 be formed of yieldable material, such as synthetic rubber, as the valve portion 166 of the valve body 160 tends to seat or seal tighter in a yieldable seat than a metal valve engaging a metal seat under normal operating conditions. It is to be understood however that both valve seats may be made of metal. The

inlet valve bodies

110 and 160 may be made of stainless steel, brass or other suitable material.

In the control unit of the character described wherein the first valve seat 112 is fashioned of metal, a high factor of safety is provided against fire damage and where the second seat is fashioned of yieldable material such as synthetic rubber, the tendency is to attain improved sealing characteristics with the valve member.

Where metal valve seats are used they may be made of stainless steel or brass. The

springs

124 and 159 for biasing the

control valves

110 and 160 toward closed position may be made of brass or stainless steel to effectively close the valves even at comparatively high temperatures.

Another feature of the dual valve control unit is that in the event a foreign particle lodges between an inlet valve and its seat, the other inlet valve arrangement will effectively prevent fuel flow when the burner is not in operation. In installations where the fuel tank 54 is disposed above the burner, the progressive lowering of the fuel level during burner operation with the flow control unit has only a minor effect on the rate of delivery of the fuel.

In installations where the fuel tank 54 is above the burner, the gravity head or fuel pressure has little or no effect on fuel delivery at the nozzle. When aspiration or reduced pressure is effective in the

fuel chambers

98 and 150, air pressure at the opposite sides of the diaphragms moves the diaphragms to open the

fuel inlet valves

110 and 160 to permit fuel flow to the fuel delivery nozzle 40. The nozzle construction 40 presents some restriction to fuel flow and hence a fuel back pressure is built up in the

fuel chambers

08 and 150 flexing the diaphragms in the opposite direction allowing the springs to move the valves to reduce or shut off fuel flow.

This back pressure tending to close the inlet valves prevents flooding or over delivery of fuel from the nozzle 40 as the fuel back pressure arising by nozzle restriction is effective on the full area of the diaphragms, this force moving the diaphragms away from the

levers

116 and 156, permits the expansive forces of the

springs

124 and 159 to tend to close the inlet valves. Where the fuel tank is disposed with respect to the burner to provide a gravity head of fuel acting against the inlet valves, the varying gravity head as fuel is consumed is changed and the fuel pressure acting to open the inlet valves is likewise changed.

As the fuel is reduced, the fuel pressure acting to open the inlet valve is likewise reduced. As this pressure of gravity head of fuel is reduced, the aspiration in

chambers

98 and 150 increases slightly and the

springs

124 and 159 are further compressed to allow the

valves

110 and 160 to be further opened to compensate in a measure for the reduced gravity head.

In prior control arrangements for combustion burners of the general character described, it has been conventional practice to employ a fuel bowl containing a float-controlled inlet valve which controls the delivery of fuel to a nozzle depending upon the level of fuel in the fuel bowl, a change in the level of the fuel in the bowl influences the opening and closing of the inlet valve during burner operations, affecting variations in the rate of fuel delivered from the burner nozzle.

In the method ofdiaphragm control of this invention, the instant response of the diaphragm to differential pressures at opposite sides thereof provides effective control of fuel flow through the control unit.

The control unit of the invention provides a high degree of safety against fuel leakage and fire hazard. In the event of the failure of airflow at the fuel delivery nozzle irrespective of the relative position of the fuel tank with respect to the burner, pressures in the

fuel chambers

98 and 150 are increased, causing the diaphragms to move in directions whereby the biasing forces of the

springs

124 and 159, acting through the

levers

116 and 156 immediately close the

inlet valve members

110 and 160 to cutoff fuel flow from the fuel tank.

If there is a failure or fracture of a diaphragm, pressure in the adjacent fuel chamber is increased and equalized with the atmospheric pressure at the opposite side of the diaphragm and the spring immediately closes the inlet valve to prevent further delivery of fuel to the burner nozzle 40. A high factor of safety against fire hazard is attained through the control unit of the invention.

FIGS. 7 and 8 illustrate a modified fuel control construction of the invention wherein a single inlet valve is controlled by differential pressures on a diaphragm. The arrangement shown in FIGS. 7 and 8 includes a body member or housing 180 having a substantially annular portion 91a defining a fuel chamber 98a, a planar surface 92a forming a seat for an annular gasket 93a which is engaged by the peripheral region of an impervious flexible diaphragm 94a forming a flexible wall of the fuel chamber 98a. The diaphragm and gasket are secured in assembled relation with the housing 180 by a closure plate 95a secured to the housing 180 by screws 96a.

The central region of the closure plate 95a is recessed or shaped to provide an air space or chamber 99a accommodating flexing movements of the diaphragm 94a, the space 99a being vented to the atmosphere through a vent opening 100a in the closure plate 95a. The diaphragm 94a is reinforced at opposite sides by metal or discs 1010. The central axis or region of the diaphragm and the discs 101a have aligned openings to accommodate a rivet 102a having a head or button 103a. The housing 180 is provided with a threaded bore receiving a tubular sleeve or valve guide member 109a in which is slidably mounted an inlet valve or valve member 1100 having a cone-shaped valve portion 111a.

An annular valve seal member 112a is held in place by the sleeve 109a, an annular gasket 114a being disposed between the upper end of the guide sleeve 109a and the bottom of the bore accommodating the sleeve 109a. The annular valve seat 112a provides a port 115a cooperating with the valve portion 111a to control or regulate fuel flow into the fuel chamber 98a.

The lever 116a, disposed in the fuel chamber 98a, is fulcrumed on a pin 117a, the long arm 118a of the lever being arranged to be engaged by the button 103a carried by the diaphragm, the short arm 120a of the lever being arranged to engage the valve member or body 110a. An expansive coil spring 124a normally exerts pressure through the lever 116a biasing the inlet valve 110a toward the valve seat 1120 to interrupt fuel flow through the inlet port 115a in the seat.

The housing 180 is provided with a boss portion 181 having a threaded inlet bore 126a to accommodate a fitting such as a fitting 106, shown in FIG. 1, arranged at the end ofa fuel conveying tube 56 connected with a tank 54 as shown in FIG. 1. The inlet bore 126a is in communication with a bore 127a in the housing 180 through interconnecting

passages

182 and 183. A portion of the bore 1270 is threaded as at 128a to accommodate a threaded plug 130a, the plug having a bore 131a to receive a cylindrically shaped fuel filter or screen 132a, the end of the screen being closed by a cup-shaped plug 133a.

The plug 130a is provided with a counterbore 134a and a peripheral recess 135a. Transverse openings 136a establish communication between the counterbore 134a and the peripheral recess 135a, the recess being in communication with the valve port 115a by a channel or duct 107a. The housing is fashioned with a threaded outlet bore 1720 in communication with the fuel chamber 98a through interconnecting passages and 186. The outlet bore 172a is adapted to accommodate a fitting, such as fitting 61 shown in FIG. 1, for conveying fuel from the chamber 98a to the fuel delivery noz zle 40 ofthe burner, shown in FIG. 1.

The control unit, shown in FIGS. 7 and 8, is arranged to be connected in the fuel supply system, shown in FIG. 1, in the same position as the unit 60. Fuel from the tank 54 is conveyed through the tube 56, fitting 106 and through the inlet bore 126a, interconnecting

passages

182 and 183, through the screen or filter 1320, through the counterbore 134a, passages 136a and 107a and past the valve member 110a whenever aspiration at the burner nozzle is effective in the fuel chamber 980 to set up reduced pressure therein.

Such reduced pressure is effective through the outlet bore 172a and interconnecting

passages

185 and 186 in the chamber 98a to cause the diaphragm to move or flex in a right-hand direction, as viewed in FIG. 7.

Such movement of the diaphragm swings the lever 116a about its fulcrum 1170 in a counterclockwise direction to permit the valve member 110a to move in a left-hand direction withdrawing the needle valve portion 111a from its seat to thereby effect fuel flow into the chamber 98a and its continued delivery to the fuel delivery nozzle 40 shown in FIG. 1.

The filter 132a screens out foreign matter that may be in the liquid fuel to minimize the liability of foreign particles lodging on the valve seat 112a. In this form of control unit where a single diaphragm actuated valve controls fuel flow to the burner nozzle, the valve seat 112a should be made of metal, such as stainless steel or brass, to resist high temperatures and reduce liability of damage by fire.

It should be noted that the short arm 120a of the lever is in contacting engagement with the valve so that when the diaphragm 94a is flexed, by aspiration or reduced pressure, in a right-hand direction, as viewed in FIG. 7, the short arm of the lever moves in a left-hand direction and the valve member 110a is withdrawn under the influence of the reduced pressure in the chamber 98a to admit fuel flow past the inlet valve into the chamber. Thus, if the fuel tank 54, shown in FIG. 1, is below the burner, the greater reduced pressure in the fuel chamber 98a causes the valve member 110a to be opened further.

If the fuel tank 54 is above the burner and a gravity head of fuel is existent in the channel 107a and the port 115a, the valve member 110a will be influenced toward open position by the reduced pressure existent in chamber 98a under the in fluence of aspiration and, in addition, the gravity or pressure head of fuel on the inlet valve tends to move the valve toward open position.

Where a single diaphragm and inlet valve control mechanism is employed of the character shown in FIGS. 7 and 8, any impairment or failure of aspiration at the burner nozzle effects an increase in pressure in the chamber 98a, the diaphragm is flexed in a left-hand direction, as viewed in FIG. 7, and the spring 124a is effective through the lever 116a to close the fuel inlet valve 11011. In the event that the diaphragm 94a becomes fractured or impaired and pressure in the fuel chamber 98a is increased by airflow through a fracture in the diaphragm, the spring 124a is automatically effective to close the fuel inlet valve 110a to interrupt fuel flow to the burner.

Thus, a single diaphragm and fuel inlet valve arrangement, shown in FIGS. 7 and 8, is effective to interrupt fuel flow except during burner operation when aspiration is effective on the fuel delivery nonle 40. Fuel will only be delivered from the nozzle 40 when differential pressures are established at opposite sides of the diaphragm 94a.

FIG. 9 is a sectional view of a portion of the construction shown in FIG. 7 illustrating a shackle connection between the lever and the valve and between the diaphragm button and the lever. In this form, the valve guide 1091; in a bore in the housing slidably accommodates an inlet valve member 11%. The diaphragm 94b is equipped with a rivet having a head l03b fashioned with a tenon 191 which is straddled by the bifurcated or forked end of the long arm of a lever fulcrumed on a pin 1 17b. The short arm 192 of the lever is bifurcated and the furcations straddle a tenon 193 formed by a recess in the valve member 110b, the recess in the valve member providing a head 194 on the valve 11%.

The shackle connection of the diaphragm button l03b with the lever and the shackle connection of the short arm of the lever with the tenon 193 on the valve member provides a positive connection whereby movement of the lever 190 in either direction effects movement of the valve member 11%. In the event that a foreign particle lodges under the valve, fuel flow ing into the fuel chamber increases the pressure which increases the valve-closin effort applied to the inlet valve through the lever. The va ve member ll0b IS normally biased under the influence of an expansive coil spring l24b to engage the cone-shaped valve portion lllb with the valve seat ll2b.

The shackle connection, provided between the lever and the valve member, eliminates any tendency for the valve to stick in the valve seat. The arrangement of FIG. 9 operates in the same manner as the construction shown in FIG. 7.

It is apparent that, within the scope of the invention, modifications and different arrangements may be made other than as herein disclosed, and the present disclosure is illustrative merely, the invention comprehending all variations thereof.

We claim:

1. A low-pressure oil burning unit comprising a burner head, a low-pressure aspirating nozzle mounted in and projected from said head, said nozzle having fuel and aspirating passages, said head having means defining a fuel passage in connection with said nozzle fuel passage, a compressor in connection with said head for delivering a high velocity flow of air to and through said nozzle aspirating passage, a supply line in connection with said fuel passage incorporating therein a control regulator including a housing having an intermediately positioned diaphragm forming two chambers, one of which is vented to the atmosphere and the other of which has an inlet and an outlet positioned in the line of flow through said regulator, and means normally sealing said inlet operative to block the flow of fuel through said other chamber and its outlet and prevent its passage to said nozzle except on the occurrence of a high-velocity flow of air through the aspirating passage of said nozzle.