US2697484A - Metering system supplying oil to burner, including air-oil separator - Google Patents

Description

Dec. 21, 1954 R. R. WITHERELL 2,697,484

METERING SSLSTEM SUPPLYING on. T0 BURNER, INCLUDING AIR-OIL SEPARATOR Filed Aug. 1, 1951 2 Sheets-Sheet l fuzz-h].

I N V EN T 0R. Fob/597' A? W/ man-u 'QTTORNEV Dec. 21, 1954 R R wlTHERELL 2,697,484

METERING SYSTEM SUPPLYING OIL TO BURNER, INCLUDING AIR-OIL SEPARATOR 2 Sheets-Sheet 2 Filed Aug. 1 1951 Ilia-5 INVENTOR. P055 P Mmmm United States Patent METERING SYSTEM SUPPLYING OIL TO BURNER, INCLUDING AIR-OIL SEPARATOR Robert R. Witherell, Bloomington, 11]., assignor, by mesne assignments, to Henney Motor Company, Inc., New York, N. Y., a corporation of New York Application August 1, 1951, Serial No. 239,693

9 Claims. (Cl. 158-36.3)

This invention relates to oil burners and has particular reference to oil burners of the low pressure type wherein an oil and air mixing nozzle is supplied with air and oil at relatively low pressures, mixed therein, and discharged as a mixture of finely divided oil particles and air into a stream of secondary air which flows past the nozzle.

In oil burners of this type the flow of oil to the nozzle is accurately metered. Some difliculty in metering the flow of oil to the nozzle has been encountered heretofore due to the presence of air or other vapors in the oil, which makes it impossible for the metering device accurately to meter the flow of oil, thereby causing variations in the oil-air mixture ratio for which the burner is set.

This invention has for one of its principal objects the provision of an oil burner system of the type referred to in which means are provided for minimizing the effect of the entrained air in the oil, and to this end I have devised a centrifuging arrangement for separating the oil from the less dense air which in conjunction with a by-pass arrangement returns substantially all of the separated air to a place where the air may be vented and from which centrifuging arrangement oil substantially free of entrained air is supplied to the metering device.

Another important object of the invention is to provide a new and improved air and fuel pumping system and construction for oil burners of the type referred to.

Other and further objects of the invention will be apparent from the following description and claims and may be understood by reference to the accompanying drawings, of which there are two sheets, which by way of illustration show a preferred embodiment of the invention and what I now consider to be the best mode in which I have contemplated applying the principles of my invention. Other embodiments of the invention may be used without departing from the scope of the present invention as set forth in the appended claims.

In the drawings:

Fig. 1 is a somewhat schematic view of an oil burner embodying my invention showing in section the fuel and air pumping unit and illustrating diagrammatically the fluid connections between various parts of the burner;

Fig. 2 is an enlarged fragmentary sectional view of the metering pump, the pressure regulator, and the centrifuge assembly;

Fig. 3 is a sectional view of the air pump taken generally along the line 33 of Fig. 1;

Fig. 4 is a sectional view of the oil supply pump taken generally along the line 4-4 of Fig. 1;

Fig. 5 is a sectional view of the metering pump taken generally along the line 5--5 of Fig. 2; and

Fig. 6 is a sectional view taken along the line 66 of Fig. 2.

The oil burner construction herein disclosed comprises in general an oil supply or suction pump indicated generally at 10, a bypass or return line 131 between the outlet 52 of said pump and the tank or reservoir 11 to which the inlet 46 of the pump is connected, a centrifugally responsive valve indicated generally at 12 constructed and arranged to resist flow of oil through such by-pass during pump operation thereby to create a pressure differential between the pump inlet and the pump outlet, the pump inlet being connected with reservoir 11 so as to draw oil therefrom, an oil and air mixing nozzle indicated generally at 14 connected to the pump so as to be supplied with oil therefrom, a pressure operated,

normally closed valve indicated generally at 16 in the connection between the nozzle 14 and the pump 10, said pressure operated valve 16 being responsive to and opened by a predetermined pressure differential created by the centrifugally responsive valve 12, said pump and centrifugally responsive valve being driven by a motor driven shaft 18, a positive displacement type of air pump indicated generally at 20 for supplying air under pressure to the nozzle 14 for mixture with the oil supplied thereto, the nozzle being constructed so as to mix the oil and air supplied thereto and to discharge a mixture of finely divided oil particles and air, a metering pump indicated generally at 22 in the fluid connection between the oil supply pump 10 and the nozzle 14 and operable for metering the flow of oil to the nozzle 14, a fan or blower indicated schematically at 24 for supplying a stream of secondary air past the nozzle 14 and into which stream the nozzle discharges its mixture of oil and air so as to provide a combustible mixture, and a means indicated generally at 26 associated with the oil pump 10 and operable for separating from the oil discharged by such pump gas which may be entrained therein and directing such gas through the by-pass so that the oil which is supplied to the metering pump 22 from the oil supply pump 10 is substantially free of entrained gas.

The upper portion of Fig. l is a sectional view of an air and oil pumping unit with the fluid flow lines shown diagrammatically, such unit conventionally being associated with a casing to which the draft pipe 28, the secondary air blower 24, and other conventional parts of the oil burner are attached or of which they form a part. The secondary air blower 24 usually is a centrifugal type of blower and is driven by an electric motor which also drives the shaft 18.

The oil and air pumping unit as shown in the upper part of Fig. 1 comprises in general a casing or frame indicated generally at 30 to which the various elements of such unit are attached. A filter chamber 32 formed by walls 34 integral with the frame 30 and a cover 36 is provided with a screen or filter 38 therein for filtering the oil as it is supplied to the unit. A hollow boss 40 on the wall 34 is internally threaded so that the oil line or conduit 41 may be connected thereto for supplying oil through the passage 42 to the chamber 32 from the oil supply 11. A pipe 44 open at the top and secured in a bore in the frame 30 communicates with a conduit 46 which leads to the intake side of the oil supply pump 10 for supplying oil from the chamber 32 to the pump 10.

The pump 10 is of the gear type and comprises (Fig. 4) gears 48 and 50, the teeth of which are arranged to mesh so that during rotation of the gears oil will be drawn through the conduit 46 and discharged through the outlet 52 of the pump into the chamber 54. The pump 10 comprises in addition the block 56, the block 58, and the plate 60 which define a pumping chamber in which the gears 48 and 50 are enclosed. The gear 48 freely rotates on a shaft 62 carried by the block 56, while the gear 50 surrounds a hollow portion of the shaft 18. The shaft 18 is provided with a concave depression 64, and the gear 50 is provided with a series of bores 66 therethrough, the bores 66 being of relatively small diameter and intersecting the central bore through the gear 50 through which the shaft 18 extends.

A ball 68 seated in the depression 64 and partly disposed in one of the bores 66 serves to couple the gear 50 to the shaft 18 for rotation therewith. In assembly of the gear 50 to the shaft 18 the ball 68 is seated in the depression 64 and the gear 50 is then axially slid over the end of the shaft 18 until the ball 68 is located in one of the bores 66. This connects the gear 50 to the shaft 18 for rotation therewith, but provides in efiect a universal connection between the shaft 18 and the gear 50, thereby permitting the gear 50 to run freely between the plate 60 and the block 56 without bias from the shaft 18, and also permitting the shaft 18 to run freely in its bearings 70 and 72 without bias from the gear 50.

The discharge chamber 54 of the pump is provided by a ring 74 which is secured to the block 56, and an end plate 76 secured to the ring 74 closes the other end of the chamber 54. The metering pump 22, the centrifugally responsive valve 12, and the air separating means 26 are disposed'in -the chamber 54 and driven by the hollow end of the shaft 18 which projects into such chamben.

the channel'92 and affording acommunication-between such channel and the chamber 54. The hollowv end of the'shaft 18" projects througha bore 96-intothepassage 88', and a ball 98seated ina concave recess .in the endof the shaft 18" and in the conical: seat 86vfunctions as a thrustbearingbetween theshaft 18 and therotor. 78'.

By reference to Fig. 1 it will'be notedthatthe spring.

0which forms a part of a running sealindicatedgenerally at"102aboutthe shaft-18- biasesnthe shaft 18 tothe right, and throughtheball' 98 biases thefinished face 104 of the rotor 78 againstthefinished face 10.6 of the end plate. 76,v the faces 104. and 106 preferably being lappedso as to provide a seal therebetween duringrotation of the rotor 78" with respect to the end" plate 76,

A plug 108 is pressedlinto and closes-one end-of the passage 88 and' is provided withva projectingpinl-lO-extending through the bifurcated endofv the shaft 1 8: so-

that'upon rotation of' the shaftthe: rotor 78-will rotate therewith. However, because of the universal joint pro vided'bythe ball 98 between the endiofthe shaftl-S- and the rotor 78, the face 104- of the rotor 78 isfree to seat against the face 106 of the end plate- 76 without l bias. An annularresilient gasket 1'12 disposedtin-agroove in the bore-96cooperates with-the outer surface of the shaft 1; to forma: seal between the shaft 18 andthe rotor 7 Within the port-90the endof the passage 88 is formed to provide a=valve-seat 1-14, and underi someconditions aball valve 116 is-movable in-response to=centrifugal force terior of the shaft. 18 forms a conduit 122 which: at one end communicates through. the bifurcated end of' the shaft 18 with the'passage' 88;v and: at its other end communicates through-the crossduct- 124. and the slots 1-25'in the plate 56- witha cavity 126, the cavity 126 being:

formed by a central opening through the frame and closedat one-end by theblockor'plate56. The compositionbearing 70 is suitably secured in position adjacent the plate by aspider- 128; The cavity-1-26' communicates by duct 130 witha threaded boss 132- externally provided on the casing: and to'which-the-returnline 131' to the oil supply 11 is connected.

It is pointedout. that the conduit 130 and the line 131,- together withthe cavity 126; theslots' 125;,the cross duct 124, the conduit- 122, the passage 88;. the-port 90, and the slots 94 communicating with the chamber' 54, form' a by-pass orreturn line between" the outlet of the pump 10- and the oil reservoir 11, and also provide a by-passbetween the inlet and outlet of the: pump 10 since the inlet of the pump'1'0 is connected through theconduit 46,. the pipe 44,'the chamber 32', and the line 41 to the reservoir-"1'1; The flow of oil: throughthis by pass between the out-let and inlet of the pump 10 is controlled by the centrifug-ally responsive valve- 12. of which the rotor 78, port- 90, the valve seat H4, and the ball: valve 116 forma part,

When the rotor 78 is at rest the port 90 will be open and the ball valve 116" will be unseated since there is no centrifugal force acting on the ball valve 116 to hold: it on its seat 114. Even if the rotor 78 stopped with the valve seat 114 directly below the ball valve 116, while the ball valve would then be seated there would be no force except that of gravity holdingthe ball valve 116 on its seat. When the ball valve 116' is unseated, oil may flow from the chamber 54 through the by-pass back to the inlet side of the pump 10.

The centrifuga-lly responsive valve 12 is of the construction disclosed and claimed in my prior copending application Serial No. 64,829, filed- December 11, 1948,

for Pressure Regulator, now Patent No. 2,606,499, issued August 12, 1952. In this type of valve construction resistance to flow of oil through the bypass is created by, the, ball. valvemember. 116 which is. directed under. the influence of centrifugal force against the oil flowing through the port into thezpassage 88 so as to generate hydraulic pressure in the chamber 54 as a function of the motor speed, the pressure generated being transmitted and directed against the actuating diaphragm of the shut-off valve 16, as will. be described hereinafter. This centrifugally responsive valve thus comprises a speed responsive pressure regulating device in which resistance. to fiow of oil through. the by-pass is obtained by impinging, the ball valve 116 under the influence of centrifugalforce against the stream of oil flowing through the port90 into the passage 88 so as to create a pressure in the chamber5'4' corresponding to the angular speed of the shaft 18.

The centrifugally responsive valve 12 preferably is constructed and arranged so that sufficient pressure differential to open the, valve 16. will be built up-v in. the chamber 54' only whensufficient speed of rotation of the shaft 18 has been attained, say, for example, ninety per cent' ofi'the, normal. running speed of the electric motor which drives the shaft 18. In this way, when the speed.

of? the, shaft 18 falls, below a. predetermined. speed, the centrifugal valve 12 will not create sufiicient back pressurein the chamber 54,.and,consequently. the valve 16 will close and thev flow of. oil to, the nozzle 14 will stop.

The sleeve arranged as shown inconjunction with the,rotor 78 and, in.the.chamber 54 functions as a centrifuging, means, operable for separating from the oil discharged by the pump, 10 gas or air which may be entrainedtherein, and it alsofunctions to-. direct such gas through the port 90 and the by-pass back to the inlet side of the pump 10. Thisjgas orair may be inv the form of air bubbles which might, get, into, the oil line between the oil supply and the pump, 10 due to the leak in such line and" because during burner operation such line is under, suction due to the operation of the pump 10. It is al'so possible that. some of thehighervolatile components of the oil might form gas bubbles under the suction. effect of the pump, 10 and under the influence of heat.

Regardless of whether suchv bubblesare, air or gas or a mixture, it is desirable to eliminate the same from the system. before theo-il flowsv through the. metering pump 22;,since the presence of gas. bubbles. will interfere with accurate metering and hence cause variations in the airoil. mixture ratio, thereby causing undesirable variations in performance of the'burner.

According to this invention, the centrifuging means of which the sleeve, 128, forms a part centrifuges the oil to the. outer part of the chamber 54,, from which it is fed through duct 136 to the metering pump 22. Since the sleeve 120 rotates with the rotor 78, at a speed of the order of 17501 R. P. M. or higher, the oil forced to the outer periphery of the chamber 54.by the rotation of the sleeve will be: substantially free of entrainedair or gas, and the air or gas in the form of bubbles; contained in the oil. located inwardly from the outer periphery of the chamber 54 willfiow through the slots 94 and the channel. 92. through the port 90 and the by-pass of which theport 90 forms a part.

It may be that the oil which is supplied to the metering pump may contain minute quantities ofair or gas, but the arrangement illustrated does function effectively to minimize the effect of entrained airin the oil and will cause such entrained gas or air to. be returned through the by-pass. In order to prevent the accumulation of such air or gas inthe chamber 32 it is desirable to use a return line from the threaded boss 132- to the oil supply so that the gas mayseparate itself fromthe; oil in the oil supply tank or reservoir.

The metering pump 22 is of the positive displacement type and. the bore 80 in the rotor 78 has secured in the center thereof a plug 140 which divides the bore 80 into cylinders 142 and 144. A piston 146 is reciprocable in the cylinder 142 and a piston 148 is rcciprocable in the cylinder 144. As shown in Fig; 5,, the outer ends of the pistons 146 and 148. are provided; with heads 150 and 1.52 which bear against andride around the inside surface of an adjustable ring 154 which is biased down- 148 radially outwardly so thatthe heads 150 and 152 thereof will always bear against the inner surface of 1 the ring 154. The springs 160 are also confined in'bores in the rotor 78. It will be apparent that as the rotor 78 rotates, the pistons 146 and 148 will be reciprocated in their cylinders since the ring 154 is eccentrically disposed relative to the rotor 78, and also that the cylinders 144 and 142 will have their ports 84 and 82 alternately brought into registry with the end of the duct 136 so that on the retract-ile stroke of the pistons oil will be drawn into the cylinders 142 and 144.

The end plate 76 is also provided with a duct 162, the end of which terminates in the port 164 in the face 106, and such port 164 is so disposed that upon rotation of the rotor 78 the ports 82 and 84 will alternately communicate therewith so that upon the discharge strokes of the pistons 146 and 148 measured quantities of oil will be discharged through such ports 82 and 84 into the port 164. The duct 162 at its other end communicates with a duct 166 which leads to the valve 16, and from the valve 16 a duct 168 leads to the interior of the oil passages of the nozzle 14.

The ring 154 may be moved so as to vary its eccentricity relative to the rotor 78, thereby to decrease the rate at which oil is discharged from the metering pump 22, the adjustment as shown in Fig. being at its maximum. A shaft 170 threadedly secured in a bore 172 and provided with a cam or wedging surface 174 is axially movable upon rotation so as to cause a ball 176 engageable with the cam surface 174 and also engageable with the ring 154 to shift the ring 154 against the spring 156 and thereby decrease the eccentricity of the ring 154 and reduce the rate at which oil is metered. The end of the shaft 170 is slotted for the reception of a screw driver, and access to the end of the shaft 170 may be had by removing the threaded plug 180 after the end cap 182 of the pumping unit is removed.

The elements 56, 74 and 76 are suitably secured, such as by bolts, to the frame 30, and if it is desired sealing gaskets as illustrated may be used between the adjacent faces of such parts.

The positive displacement type of air pump 20 is secured to the other side of the frame 30 and consists of end plates 183 and 184 between which a cylinder block 186 is secured, and such parts likewise may be bolted to the frame 30. The bearing 72, similar to the bearing 70, may be secured to the block or plate 184 and the frame 30 may be secured to a part of the oil burner housing, such as an extension 188 of the fan housing. The shaft of the electric motor which drives the fan 24 preferably is directly coupled to the shaft 18 for driving the same with the fan 24 so that secondary air will always be supplied past the nozzle 14 of the burner during burner operation. The running seal 102 disposed about the shaft 18 forms a seal between the same and the pump 20 and closes the lefthand side of the cavity 126 in the frame 30.

The air pump as shown in Fig. 3 is of the rotary sliding vane type and includes a rotor 190 having slots in which vanes 192 are reciprocable, the rotor 190 being eccentrically disposed relative to the pump cylinder 194 and being mounted on the shaft 18 for rotation therewith. A ball 196 seated in a concave depression in the shaft 18 and disposed in a bore 198 in the rotor 190 forms the same kind of connection between the rotor 190 and the shaft 18 as is provided by the ball 68 between the gear 50 and the shaft 18. The cylinder 194 is provided with an air inlet 200 and an outlet 202. A valve controlled by-pass 204 is provided between the duct 206, which is connected with the outlet 202 of the air pump, and a duct 208 which communicates with the intake 200 in order that the discharge pressure of the pump 20 may be controlled. The duct 208 at its other end communicates with a bore 210 in the valve 16 in which a sleeve 212 is arranged, the sleeve 212 being connected at one end to the oil line 168 which leads to the nozzle and at its other end forming a movable valve member 218. There is sufiicient clearance provided between the sleeve 212 and the bore 210 from the valve chamber 216 to the place where the end of the duct 208 communicates with the bore 210 to permit the flow of small amounts of oil from the chamber 216 into the duct 208 and thence under the suction effect of the pump 20 into the pump for lubrication purposes.

The valve 16 comprises a casing in which the chamber 216 is provided and includes the valve seat 214 and the movable valve member 218 which is adapted to seat on the seat 214 for shutting of the flow of oil from the chamber 216 through the sleeve 212 and the duct 168. The chamber 216 is in communication with one end of the duct 166, the other end of which is supplied with measured quantities of oil from the metering pump 22. The movable valve member 218 is carried by a reciprocating piston-like member 220 which reciprocates in the sleeve 222 and which is connected to the diaphragm 224 so as to be moved thereby. A spring 226 confined between one end of the casing of the valve 16 and the diaphragm 224 biases the valve member 218 toward its seat 214, thereby to close the valve 16.

A duct 228 communicates at one end with the chamber 230 on one side of the diaphragm and at its other end with the cavity 126, while another duct 232 communicates at one end with a chamber 234 to which the other side of the diaphragm 224 is exposed and the chamber 54 so that the pressure in the chamber 54 will be transmitted to one side of the diaphragm 224 so as to efiect opening of the valve 16 when the pressure in the chamber 54 attains a predetermined degree. As previously pointed out, this will be determined by the action of the centrifugally responsive valve 12.

Thus, when the valve 16 is open metered quantities of oil will be supplied to the oil passages 238 of the nozzle 14 from the pump 10 under the regulation of the metering pump 22. At the same time air under pressure will be supplied to the air passages 240 of the nozzle 14 from the air pump 20 through the duct 206 which communicates with the air passages 240 in the nozzle 14. The air passages 240 and the oil passages 238 intersect in the nozzle so as to mix the oil and air, and such mixture is discharged in the form of a finely divided spray of oil and air particles through the nozzle orifice 242. The nozzle 14 is of the type disclosed in the Williams Patent No. 1,934,755, issued November 14, 1933.

Oil and air are supplied to the nozzle at substantially the same pressure and at a pressure which may be of the order of two to ten pounds per square inch. The oil and air mixture discharged from the nozzle 14 is discharged into the secondary air stream which is caused to flow through the draft tube 28 by the blower 24, thereby to form a combustible mixture which is ignited by suitgble ignition means including a pair of spaced electrodes While I have illustrated and described a preferred embodiment of my invention, it is understood that this is capable of modification and I therefore do not wish to be limited to the precise details set forth but desire to avail myself of such changes and alternations as fall within the purview of the following claims. a

I claim:

1. An oil burner comprising an oil pump having an outlet, a discharge chamber in communication with said outlet to receive oil discharged by said pump, an oil and air mixing nozzle connected to said discharge chamber so as to be supplied with oil therefrom, a pump for supplying air under pressure to said nozzle for mixture with the oil supplied thereto, said nozzle being constructed so as to mix the oil and air supplied thereto and to discharge a mixture of finely divided oil particles and air, a metering device for metering the rate at which oil is supplied to said nozzle from said discharge chamber, means for supplying a stream of secondary air past said nozzle into which stream said mixture of oil and air is discharged, and means operable for separating from the oil discharged by said oil pump, gas bubbles which may be entrained therein and for discharging such gas bubbles from said burner so as to prevent such gas bubbles from passing through said metering device to said nozzle, said separating means including a rotor in said chamber having a passage therein through which said gas bubbles are discharged and a sleeve mounted on said rotor radially outwardly of said passage.

2. An oil burner comprising an oil pump having an outlet, a nozzle connected to said pump outlet so as to be supplied with oil therefrom, said nozzle being constructed so as to discharge a spray of finely divided oil particles, a metering device operable for metering the discharge of oil from said nozzle, means for supplying a stream of secondary air past said nozzle into which stream said spray of oil is discharged, and means operable for separating from the oil discharged by said oil pump, gas bubbles which may be entrained therein and for discharging such gas bubbles from said burner other-- wise than through said nozzle, said separating means including a rotor having a: passage therein communicating with said. pump outlet and a sleeve mounted on saidrotor radially outwardly of said passage.

3. An oil burner comprising an oil pump having an inlet and an outlet, means providing a. by-pass between said pump outlet and said inlet, an oil and air mixing trained therein and directing such gas bubbles throughsaid by-pass thereby preventing, the same from passing.

through said metering pump and nozzle, said separating means including a rotary member having passage means therein forming a part of said by-pass, and means arranged on said rotary member radially outwardly of said passage means and defining, together with said rotor, an annular channel communicating with said pump outlet and with said passage in said rotary member.

4. An oil burner comprising an oil pump having an inlet and an outlet, means providing a discharge chamber in communication with said outlet to receive oil discharged by said pump, a bypass between said discharge chamber and said inlet, an oil and air mixing nozzle connected to said discharge chamber and adapted to mix oil and air supplied thereto and to discharge a mixture of finely divided oil particles and air, a metering device operable for metering the flow of oil from said discharge chamber to said nozzle, said metering device including a centrifuge means in said chamber spaced from the inner peripheral wall of said chamber so as to define therewith a space through which oil flows from said chamber to said metering device, said centrifuge means having passage means therein communicating with said chamber radially inwardly of said space and forming a part of said by-pass whereby gas bubbles which may be entrained in the oil discharged by said pump into said chamber are separated from the oil flowing through said space and are discharged through said-by-pass.

5. An oil burner comprising an oil pump having an inlet and an outlet, means providing a discharge chamber in communication with said outlet to receive oil discharged by said pump, an oil and air mixing nozzle connected to said discharge chamber and adapted to mix oil and air supplied thereto and to discharge a mixture of finely divided oil particles and air, a metering device operable for metering the flow of oil from said discharge chamber to said nozzle, said metering device including a rotor in said chamber having passage means therein communicating with said chamber and said pump inlet, and means for separating from the oil in said chamber, gas bubbles which may be entrained therein thereby preventing such gas bubbles from passing through said metering device and nozzle, said separating means comprising a sleeve mounted on said rotor radially outwardly of said passage means in said rotor.

6. An oil burner comprising an oil pump having an inlet and an outlet, means providing a discharge chamber in communication with said outlet to receive oil discharged by said pump, a by-pass between said discharge chamber and said inlet, an oil and air mixing nozzle connected to said discharge chamber and adapted to mix oil and air supplied thereto and to discharge amixture of finely divided oilparticles and air, a metering device operable for metering the flow of oil from said discharge chamber to said nozzle, and means for separating from the oil in said discharge chamber, gas bubbles which may be entrained therein thereby preventing such gas bubbles from passing through said metering pump and nozzle, said separating means comprising a rotor in said chamber having passage means therein communicating with said chamber and forming a part of said by-pass through which said gas bubbles are discharged, and a sleeve surrounding said rotor and arranged radially outwardly of said passage means in said rotor.

7. An oil burner according to claim 6 wherein said sleeve is spaced from the inner wall of said chamber and defines therewith a space through which oil flows from said chamber to said metering device.

8. An oil burner comprising an oil pump having an inlet and an outlet, means providing a discharge chamber communicating with said outlet to receive oil discharged by said pump, a nozzle connected to said chamber so as to be supplied with oil therefrom, a metering device operable for metering the flow of oil from said chamber to said nozzle, and means for separating from the oil in a said discharge chamber, gas bubbles which may be entrained therein thereby preventing such gas bubbles from passing through said metering device and nozzle, said separating means comprising a rotary member in said chamber having passage means therein communicating with said chamber and said pump inlet, and a sleevemounted on said rotary member radially outwardly of said passage means.

9. An oil burner comprising an oil supply pump having an outlet, an oil and air mixing nozzle connected to said pump so as to be supplied with oil therefrom, an air pump for supplying air under pressure to said nozzle for mixture with the oil supplied thereto, said nozzle being constructed so as to mix the oil and air supplied thereto and to discharge a mixture of finely divided oil particles and air, a metering pump operable for metering the rate at which oil is supplied to said nozzle from said 011 pump, means for supplying a stream of secondary air past said nozzle into which stream said mixture of oil and air is discharged, and means operable upon operation of said metering pump for separating from the oil discharged by said oil pump, gas bubbles which may be entrained therein and for preventing such gas bubbles from passing through said metering pump to said nozzle, said separating means includes a chamber connected to the outlet of the pump and a rotary sleeve in said chamber, said metering pump having its inlet connected to said chamber radially outwardly of said sleeve and a communication opening into said chamber within said sleeve through which said gas bubbles are discharged from said oil burner.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,345,895 Seguin July 6, 1920 2,032,291 Lum Feb. 25, 1936 2,484,920 Witherell Oct. 18, 1949 2,606,603 Witherell Aug. 12, 1952

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