US2681695A

US2681695A - Pressure-atomizing type oil burner having a high-frequency vibratory-piston oil-supply pump

Info

Publication number: US2681695A
Application number: US269077A
Authority: US
Inventors: Philip H Bills; Joseph A Logan; Theodore J Mesh
Original assignee: Gilbert and Barker Manufacturing Co Inc
Current assignee: Gilbarco Inc
Priority date: 1952-01-30
Filing date: 1952-01-30
Publication date: 1954-06-22
Anticipated expiration: 1971-06-22

Description

PRESSURE-ATOMIZfNG TYPE OIL BURNER HAVING A HIGH-FREQUENCY VIBRATORY-PISTON OIL-SUPPLY PUMP Filed Jan. 30, 1952 5 Sheets-Sheet l z; 70/445? ll i 5 69% w? Q; 144 8 64 14 35/ INVENTORS June 22, 1954 P. H. BILLS ETAL 2,681,695

PRESSURE-ATOMIZING TYPE OIL BURNER HAVING A HIGH-FREQUENCY VIBRATORY-PISTON OIL-SUPPLY PUMP 5 Sheets-Sheet 3 Filed Jan. 30, 1952 N H a ml 1 7 M 6 6 9 Mm m n y M w A 0 .J i 6AM a a m u a m w m M m g m1 W m vv l ii liarg ficiw June 22, 1954 Filed Jan. 30, 1952 P. H. BILLS ET AL 2,681,695 PRESSURE-ATOMIZING TYPE OIL BURNER HAVING A HIGH-FREQUENCY VIBRATORY-PISTON OIL-SUPPLY PUMP 5 Sheets-Sheet 4 INVENTOFZS FH l LIP H. B ll l S JOSEPH A. LOGAN THEODORE J. MESH ATTORNEYS June 22, 1954 P. H. BILLS ETAL PRESSURE-ATOMIZING TYPE OIL BURNER HAVING A HIGH-FREQUENCY VIBRATORY-PISTON OIL-SUPPLY PUMP Filed Jan. 30, 1952 5 Sheefcs-Sheet 5 FIG-J12 FIG.II

TIME IN SIYTIETH OF SECONDS TIME IN SIXTIETHS OF SECONDS TIME IN SIXTIETHS OF SECONDS N% E 5 mfmm m OLOJ. N J U R N E O E A T NPPD A H s%% Patented June 22, 1954 UNITED STATES RATENT OFFICE PRESSURE-ATOMIZING TYPE OIL BURNER HAVING A HIGH-FREQUENCY VIBRA- TORY-PISTON OIL-SUPPLY PUMP Application January 30, 1952, Serial No. 269,077

3 Claims. 1

This invention relates to an improved oil burner having a mechanical or pressure atomizing nozzle, supplied with liquid by a reciprocating-piston pump, which is controlled by an electro-magnet, supplied with alternating current through a half-wave rectifier, so that the pump piston is reciprocated at the frequency of the alternating current, say for example, 3600 cycles per minute.

This application is a continuation in part of our application, Serial No. 189,741, filed October 12, 1950.

The use of a pump of the type described as an oil supply means for a mechanical or high-oil pressure atomizing nozzle has many important advantages over the conventional rotary pump, heretofore used for the purpose in connection with oil burners adapted for house-heating service. Oil is pumped only at the rate that it is consumed; the pump is self priming; no cut-off or by-pass valves are required to respectively limit the minimum and maximum pressures at which oil is supplied to the nozzle; the pump stops instantly, when the power is cut off, thereby affording a quick cut-off of oil from the nozzle; a large saving in power is effected; the pressure of the oil supplied to the nozzle and the energy imparted to such oil is easily and conveniently varied by varying the voltage applied to the electro-magnet which actuates the pump.

The invention has for an object the provision of improved means for mounting a high-frequency vibratory-piston oil-supply pump on an oil burner of the pressure-atomizing type.

This and other objects will best be understood from the detailed description of one illustrative example of the invention in the accompanying drawings, in which:

Fig. 1 is a side elevational view of an oil burner embodying the invention;

Fig. 2 is a sectional elevational View taken on the line 2-2 of Fig. 3 and drawn to a larger scale;

Fig. 3 is a rear elevational view of the burner;

Fig. 4 is a fragmentary cross sectional view taken on the line 4-4 of Fig. 1;

Fig. 5 is a sectional plan view taken on the line 5-5 of Fig. 1;

Fig. 6 is a sectional elevational view taken on the line 66 of Fig. 3;

Fig. 7 is a cross sectional view taken on the line 1-1 Of Fig. 6;

Fig. 8 is a diagram of the electrical connections of the burner;

Fig. 9 is a side elevational view of the burner, showinga modification in the fuel feeding means Fig. 10 is an enlarged fragmentary sectional elevational view of the pump, showing a dia phragm and chamber therefor connected with the outlet of the pump;

Fig. 11 is a full-size tracing taken from the screen of an oscilloscope and showing the form of the oil pressure wave developed by the pump, when operating alone, without any pulseabsorbing means or flexible tubing between the pump and nozzle;

Fig. 12 is a similarly-made tracing showing the efiect on the oil pressure wave, when a certain length of copper tubing is introduced between the outlet of the pump and the nozzle; and

Fig. 13 is a similarly-made tracing showing the oil pressure wave when the diaphragm of Fig. 10 and the copper tubing shown in Fig. 9 are used between the outlet of the pump and the nozzle.

Referring to these drawings, the invention will be disclosed with reference to its use in an oil burner structure. For other uses, where combustion of the sprayed liquid does not occur and it is merely desired to spray the liquid, the airsupply and ignition provisions, hereinafter disclosed, may be omitted.

In these drawings, a gun-type oil burner has been disclosed which, in general, is of well known form, although it embodies occasional improvements in the burner structure and, of course, the novel fuel supply and atomizing means of this invention.

Referring first to Fig. 6 thereof, the burner includes an air-supply fan I, mounted in a casing 2, which is suitably supported as by a floor plate 3 and an adjustable post 4. Casing 2 (see Fig. 4) has openings 5 and 5' in opposite end walls 6 and 6', respectively, and a peripheral outlet 1 (Fig. 6) leading into an air chamber 1, which overlies the fan and to which one end of a tube 8 is connected. This tube conducts all the air for combustion and has its other end open and adapted to discharge into a furnace. Near the discharge end of tube 8 is a high-oil-pressure iatomizing nozzle 9 of the usual well konwn form for producing a spray, when supplied with oil or other liquid under a pressure greater than a predetermined minimum value. On the outer end of the tube 8 is an air director Ill for turning the air stream into the spray of atomized oil emitted from the nozzle. In the tube is a turbulator for whirling the air prior to its mixing with the oil spray, such turbulator comprising a series of spiral vanes H projecting inwardly from an annular ring H. The opening 5 in the fan casing (Fig. 4) receives a frusto-conical air director E2, the flanged outer end of which is clamped to end wall 6 by a ring l3, secured by screws 14 to such wall. The opening l2 within the air director 12 forms the main air inlet for the fan. The other opening is covered by a plate 55, which is secured to end wall 6' by screws l6 and which has a plurality of openings I! therethrough. The fan I has its hub fixed, as indicated, to the shaft iii of an electric motor [9. The latter is fixed to the described plate [5 by screws 26, which pass through the plate and thread into lugs 2| on the inner end wall 22 of the motor. Between these lugs and the end wall are passages 23, leading to the openings I1 and thus to the interior of the fan casing. Thus, air is drawn in by the fan i, partly through the main inlet I2 and partly through the auxiliary inlet, comprising the passages 23 and holes I], and forced out through outlet 1 (Fig. 6) into chamber 1' and from the latter through tube 8, the air being whirled by the turbulator vanes H and just before it is directed by cone It into the spray of atomized oil emitted from the nozzle 9.

The particular motor shown is a very small one, say for example, a one thirty-fifth horse power, split-phase, 115 volt, 60 cycle, alternating-current motor. It customarily has ventilation openings in both end walls and a ventilating fan (not shown) fixed to its shaft inside the casing. Motors of this type tend to run rather hot and it is desirable to space the inner end wall 22 from the plate 45, to which it is fastened and provide for a flow of cooling air along this inner end wall. Such air, warmed by the heat exchange with the motor, is drawn in by the fan, as above described, and utilized for combustion.

The rate, at which air is supplied to tube 8,

is variable by adjustment of a damper 24 (Fig. 6), mounted on a pivot rod 25, fixed at its ends (Fig. 4) in the walls 6 and 6' and movable by turning a screw 25 (Fig. 6). The latter passes through casing 2 and is threaded in a nut 21, w

swivelled in the damper. The head of the screw is held against the outer face of casing 2 by a spring 23, mounted on the screw and acting between the inner face of the casing and a collar 29, fixed on the screw.

The oil is supplied to nozzle 9 by an electromagnetically operated reciprocating piston pump which is mounted on one side wall of the casings 2, as shown in Figs. 1, 3 and 5. This pump and the electromagnet, which actuates it, are mounted in a casing, comprising a main section or body 3! and a cover 32. The lower end of the body and the upper end of the cover are respectively providedwith shoulders 33 and 34 and

hubs

35 and 36, projecting in opposite directions one from each of the shoulders. A grommet 37, of rubber-like material, encompasses each hub and abuts the adjacent shoulder. Each grommet (Fig. 5) has a circumferential groove in its outer periphery to receive a part of a supporting arm 38 and a U-shaped clamp 39, which is fixed at its ends to the arm by bolts 49. Both arms 38 (Fig. 3) project outwardly at right angles from a common support 4|, which is fixed to casing 2 by screws 42.

Referring next to Fig.2, the body 3! of the pump and its cover 32 are made of suitable magnetic material, and as shown of cast iron. The

upper portion of body 3| has a large cylindrical recess in which is mounted the annular coil 43 of the electromagnet. Body 3| has a hole coaxial with the magnet coil recess and extending from the latter through the body to the bottom thereof and fixed, as by a drive fit, in this opening is a rod 44, which is also of suitable magnetic material and in which is formed the cylinder 45 of the pump. Rod 44 has an integral upward extension 45 projecting through the central opening in coil 43 and forming the core of the electromagnet. Slidable in cylinder 44' is a piston 46, which extends upwardly through core 4%: and has fixed to its upper end at a location above the upper end of the core, an armature 41. The latter preferably has a frusto-conical lower end to cooperate with a complementary-shaped recess in the upper end of the core 45. The frusto-ccnical face of armature 41 preferably has a series of brass inserts 4'? which project outwardly from its face a small amount, preventing contact between the two cooperating magnetic faces and sticking of such faces, one to the other, by residual magnetism. The cover 32 has a central opening 48 therein, which slidably receives the armature, and in this opening are a series of angularly-spaced longitudinally-extending grooves 49 to allow liquid to pass the armature. A spring 50, which is located in opening 43, acts between suitable seats, one on the end wall of the opening and one-on the top of the armature and encircling rod 45, and tends to move the armature downwardly. A similar spring 5|, mounted at its ends in suitable seats in recesses in the bottom or" the armature and the upper end of core 45, tends to move the armature upwardly. The armature is balanced between these two springs, which have the same dimensions and are under the same initial stress. The armature is shown in its rest position midway of its stroke. The mass of the armature 41 and rod 46 and the characteristics of the springs 50 and 5! are so selected as to have a natural period of vibration substantially equal to the frequency of the alternating-current supply to which the coil 43 is adapted to be connected. As shown diagrammatically in Fig. 8, the coil 43 is adapted to be connected to a volt, 60 cycle, alternating current source through a suitable half-wave rectifier 52, which may, for example, be a selenium cell rectifier. Thus, when the control switches, indicated in the diagram and later to be described, are closed, the coil 43 will be energized intermittently in pulses at the rate of 3600 per minute. When coil 43 is energized,

the armature 41 (Fig, 2) will be drawn down wardly toward the core 45 to actuate piston 45 on its pressure stroke, the magnetic circuit extending through core 45, acrossv an axial air gap to armature 43, through the latter and across a small radial air gap to cover 32, outwardly through the cover in radiating paths to the annular shell which surrounds coil 43, downwardly through this shell and thence inwardly in radiating paths to the lower end of core 45. When coil 43 is deenergized in the interval between two successive energizing electric pulses, the armature 41 will move away from core 4-5 to and above the rest position illustrated. The stroke of the pump is variable, depending on the power applied to the coil and the resistance en-' countered by the piston. The resonant springs 50 and 5! serve to keep the armature 41 and piston 46 in vibration with only a small amount of assistance from coil 43, leaving the major part of the energy developed by the coil for the performanceof useful work.

5. The pump cylinder 44 has an inlet port 53, communicating with a passage 54, which is formed in body 3| and extends horizontally outward and thence vertically upward to a cylindrical space 55, formed. in cover 32 and located above coil 43. This space is connected by the described passages 49 and hole 48 to the oil inlet 55, which connects with the hole 48 by means of the central opening through the upper seat of spring 56. This inlet is connected by a suitable conduit, such as copper tubing 51', to a suitable oil supply tank (not shown), the tubing preferably having a coil 51' therein (Figs. 1 and 3). The coil 43 (Fig. 2) is suitably sealed off from the oil-containing chamber 55, as by a circular member 58, which closely fits around core 45 and the peripheral wall of the coil-containing recess and has inner and outer seal rings 59 to engage such core and wall. The pump cylinder is provided with a check valve in its outlet, such as the ball valve 60, which is held closed by a spring Bl, acting against a seat on the upper end of a screw 62. The latter is threaded into the lower end of member 44 and closes the lower end of the opening therein. The outlet valve 60 opens into an outlet chamber 63, formed in member Ml, and this chamber connects with an outlet passage 64 formed in the body 3|.

The outlet passage 64 delivers the pumped oil into a cylindrical chamber 65, formed in the lower part of body iii. A cover 66, secured to the body by screws H, provides access to the chamber and has a central tapped opening therein which receives an outlet pipe 58. Within the chamber 65, is a block 69 of suitable resilient material, which in this case, .is composed of particles of ground cork held together by a rubber-like binder. The block is square in cross section and its four longitudinal corner edges engage the cylindrical wall of chamber 65, leaving four longitudinal passages for the oil. Protuberances H3 on the end walls of this chamber engage the ends of the block and hold them spaced from the end walls to enable oil from passage 64 to flow outwardly to said longitudinal passages and thence inwardly from the latter to the outlet pipe 68. One purpose of this arrangement is to smooth out the pulsations in the stream of pumped oil. The pressure of the pumped oil will vary in a wave which rises from a minimum to a maximum and above the lower pressure limit of the atomizing nozzle 9. As is well known, if the pressure of the oil fed to a pressure or mechanical atomizing nozzle falls below a certain critical value, the nozzle will not produce a spray. Hence, it is essential to provide a limitin means which will maintain minimum pressures above this critical value and high enough to insure that the nozzle will be operative to produce a safe and stable spray under all conditions usually encountered in practice.

The pipe 68 delivers the oil stream into a pressure-regulating device, which is contained in a casing H, having a cover 12, held in place by screws 13. The pipe 68 is connected to the end of casing 1|, opposite from the cover, and opens into a passage 14, having a counterbored part, in which is located a ball '55. This ball is not a valve in the usual sense becauseit never closes in normal operation. Rather it is an obstruction, which may be variably positioned to variably restrict the effective area of the passage 14, accordingly as variations in pressure of the pumped oil occur. Voltage variations in the alternatingcurrent supply will cause variations in pressure of the pumped oil. The pressure varies directly with the voltage and, in the present example would vary about four pounds per square inch for each change of one volt in the voltage of the alternating current supply. It is necessary, therefore, to compensate for fluctuations in line voltage, which might under some circumstances render the nozzle inoperative and in others would cause too wide variations in the firing rate for satisfactory operation. The obstruction i5 is one way of compensating for such voltage variations and thereby maintaining the oil pressure at the nozzle within acceptable limits. By oil pressure, is meant the pressure, which shows on a gauge, that is average pressure. The obstruction ball 15 is moved by a plunger '56, fixed to one end of a rectangular frame T5. The other end of this frame has fixed thereto one end of a closed bellows 13, containing a spring i9, tending to separate the ends of the bellows. The other end of bellows i8 is fixed to one end of a second rectangular frame til, the other end of which is fixed to the cover l2, and, as shown, by means of a screw 6%, threaded into an opening in cover 12. The frame at has openings 36' to slidably receive one end of frame i? and limit its movement toward ball 75. The outer end of such opening is closed by a screw 82. By removing screw $2, screw 8| may be turned to vary the position of frame and thus the force exerted by spring "59 tending to expand the bellows and draw plunger "iii to the left to decrease the restriction in passage M. In the example herein shown, the bellows will not be contracted until the oil pressure reaches pounds per square inch and ball 75 presents the least restriction. This is the position of the ball for the low limit of voltage regulation, say for example 100 volts. Increase in the line voltage causes the pump to develop more pressure which tends to contract the bellows and move the frame ll and plunger '56 to the right to increase the restriction of passage Hi and cause a greater pressure drop in the oil. On a decrease in the voltage supplied to coil 43, the pump will develop less pressure and the variable obstruction 75 will be moved to the left to decrease the restriction in passage 14, decreasing the pressure drop and thereby increasthe pressure of the oil supplied to the nozzlev The obstruction would be in its mid position a, normal voltage, say for example, volts. and would move to the right or left to increase or decrease the restriction as the voltage rises or illlS respectively. With this arrangement, the pressure of the pumped oil may be maintained substantially constant over a range of voltage variations from 100 to 130.

As shown, a light spring 83, acts between the ball 75 and a shoulder on plunger 15, but this spring is not strong enough to move the ball against the seat in the counterbore of passage 14 during normal operation. It merely prevents the ball from rattling.

The outlet of the pressure-regulating device is connected by a suitable conduit to the atomizing .nozzle 9. As shown, this conduit includes a copper tube 84 (Fig. l) which extends upwardly from the outlet of the regulator, has a coil 84' formed therein and then enters through a notch in the side wall of easing 2 into the rear end of the chamber 1', where it extends forwardly,

as shown in Fig. 5, and is connected by a union '81, which are mounted in insulators 88 and have their rear ends connected by wires 89 with the high tension terminals Gil (Fig. 6) of an ignition transformer, mounted in a case 9|, fixed on top of casing 2.

The nozzle 9, turbulator l l--l l, and electrodes 81 may be supported in any suitable way in tube 8, desirably in the manner indicated in Fig. 5, to permit convenient withdrawal of these parts in assembled relation from the tube 8 and the aligned chamber '1', after the closure plate 92 for the rear end of chamber '5' and its retaining screws 93 have been removed. To this end, a pair of rods 94 are fixed at one end to the ring H of the turbulator, one at each of two diametrically opposite points thereon, and these rods extend rearwardly in spaced, parallel through tube 8 and through chamber 1, termihating in outwardly-bent parts 95, the outer ends of which are received one in each of two notches formed one in each of two opposite side walls of the casing 2. Theplate 92 retains these ends 95 in their notches. Fixed at its ends to rods 94 and spanning the space between them, is a support 9G having a central hub, in which the nozzle-supporting tube 36 is fixed, and two upper hubs in which the insulators 8B are fixed. The support as also has a central depending hub, to which an air-distributing bafiie 91 is fixed. It will be clear that when plate 92 is removed, the ends 95 of rods 94 are released. The high tension wires 89 will then be disconnected from terminals to and the oil pipe 8d will be disconnected by removing union 85 or 35', after which the nozzle 9, its support til, the electrodes 8? with their insulators 23 and the turbulator i may be withdrawn for inspection, cleaning or repair.

The invention includes a control switch 98 for the coil 43 or" the electromagnet. As shown in Fig. '8, this coil, the switch es, the half-wave rectifier 52, and a variable resistor 919 are included in series in a circuit lllil which is shunted across the wires it! and H32 that supply the fan motor I9 and the primary lbs of the ignition transformer, the secondary Hi l of which is connected by the described wires 89 to the ignition electrodes ill. Any suitable control may be provided to start and stop the motor i9 and ignition transformer and such a control has been indicated, simply and schematically, by a thermostat switch lt5, which usually is responsive to temperature in the space to be heated and con nects wire ill! to a wire it'd, when there is a demand for heat. The wires 1?. and W6 are adapted for connection to a suitable source of electricity, say for example a 115 volt, 6O cycle, alternating-current source. The electromagnet 43 is adapted to be energized only after the air supply has been well started by the motor. Thererelation 7 means of the variable resistor so.

fore, the closingof switch 88 is delayed, as by 8 quency of the alternating current. Theresistor' I0! is shunted across the rectifier to allow a small amount of current to flow to coil 53 in the intervals between the aforesaid pulses for the purpose of demagnetizing the core to avoid possible sticking of the armature thereto.

The switch 93 is shown in Figs. 1 and 4 as a micro-switch, mounted on an angle-iron shelf Hi8 fixed to the end wall of a cylindrical case I89, having its other end closed by a disk cover lit, secured by screws ill to the case. This case His is supported by four angularly-spaccd arms ill from the described ring l3, leaving openings H3 through which air may enter to the main'inlet opening E2 of the fan. The switch 98 has an actuating plunger 93 and suitable spring means (not shown), tending to move the plunger to the left, as viewed in Fig. l, into closed position. The switch plunger 88 is actuated by a plunger 1 M, which is slidably mounted in a hub on the end wall of case $89. This plunger lid is shown held in its right hand and switchopening position by the flanged and closed outer end of a tube H5, which is slidably mounted on a rod llil, having a flanged end, as indicated to the drive shaft iii of motor it. A spring HT encompasses rod lie and acts between the flange on the rod and the adjacent end of tube H5 to force the latter to the right and press the plunger lit and the plunger 98 of switch 98 to open the switch. The flanges of rod H6 and tube H5 are interconnected by flexible metal bands HS, each having fixed to it at a point betion and continuing until it disengages from the plunger 5 M. A small spring iii] takes up the lost motion and holds plunger l id in contact with plunger 93 and out of contact with the outer end of the rotating tube i It. Spring 213 is not strong enough to move the switch plunger 38 against its internal actuating spring (not shown).

In operation, the rate of flow of oil from the V nozzle 9 is controlled by varying the power applied. to coil 33, which ma be done in any suitable way. As an illustrative example, the variable resistor es is shown for the purpose. With a selected size of atomizing nozzle, there will be a certain amount of load imposed on the pump and the power applied to the magnet is adjusted to that load. Preferably, the magnet is designed to operate the piston at slightly less than full stroke for the largest size nozzle to be used. Lesser rates of flow can then be secured by in- 'cluding more resistance in the circuit, as by Slightly less than full stroke operation is desirable to avoid noise in operation. It should be noted that the nozzle selected does not have to be operated at the rate which is specified for it to be operated. The one size nozzle can be operated at different rates by varying the pressure of the oil supplied to the nozzle, such pressures being variable, as

for example from a minimum of 35 p. s. i. to a maximum of 200 .p. s. i. by varying the voltage applied to the magnet of the pump. Having selected the nozzle and secured the desired rate of oil flow, the'rate of airflow is adjusted by means of screw 28. This adjustment may be made for a high percentage of 002 because the oil flow is delayed until good air flow is produced.

in order to avoid smoky operation during the starting and stopping intervals of each run of the burner.

In normal operation, on a demand for heat from the burner, switch I closes and starts the motor it, which drives fan i causing the latter to produce a flow of air through tube ii and past the turbulator vanes ll. As soon as the fan nears full speed, the centrifugal switch 98 closes to connect coil 43 to its alternatingcurrent supply, and the fuel pump is set in action. The ignition transformer may be energized with the motor 19, as shown, or it may be delayed until coil 43 is energized. With the pump in operation, oil is fed to nozzle 9 and emitted in a finely atomized conical spray. The air mixes with this spray and the mixture is ignited by sparks produced between the electrodes 81.

As differentiated from the common means of supplying oil to a mechanical atomizing nozzle, the stroke of the fuel pump is variable according to the load and according to the power applied. All of the oil pumped goes to and through the nozzle. Oil is supplied only at the rate it is consumed. None of the oil is by-passed, as is the case with the usual rotary pump driven at constant speed by an electric motor. There the pump is designed to pump oil at a far greater rate than it is used and all excess oil is bypassed. The rotary pump may by-pass as much as 17 gallons per hour all of which has to be raised to the high pressure say for example 100 p. s. i. There, a cut-ofi valve prevents flow of oil to the nozzle until a predetermined minimum oil pressure has been established and a relief valve opens a by-pass as soon as a predetermined maximum oil pressure has been established. There, wide fluctuations in line voltage would slow the motor, fan and pump but not so much as to lower the oil pressure below the critical lower limit at which the nozzle is inoperative to produce a spray.

With a pump of the character described, as the line voltage falls, the pressure of the pumped oil falls with it in direct proportion and may go all the way to zero or until the pump outlet valve closes and this outlet valve is provided merely as a check valve and not to establish a lower limit of oil pressure. Actually, in the present pump, operated with the described current and supplying a pressure atomizing nozzle rated at one gallon per hour (when operated at a pressure of 100 pounds per square inch, and without the voltage-pressure control herein disclosed), the oil pressure varied 4 pounds per square inch for each one volt change in voltage. The Underwriters require safe operation of a burner at from 85% to 115% of normal voltage or from 93 to 127 volts, assuming normal voltage to be 115. A variation of 29 volts would mean a variation of 115 pounds in oil pressure which of course is altogether too great to be tolerated. The firing rate would vary widely and also the pressure might very well drop so low that the nozzle would cease to produce a good spray. Hence, the regulator disclosed is essential in a system of this kind. It is not a pressureregulator of the ordinary type, in which a valve opens at a predetermined pressure and by-passes excess oil to keep the stream pumped to the nozzle at a constant pressure. Such a valve would be useless here because the instant it opens, the pump is unloaded and goes to full stroke operation, becoming very noisy. What the present regulator does is to compensate for variations in line voltage. As long as this voltage is normal, the regulator does not function. It comes into play only when the line voltage increases or decreases from normal and. then it prevents the Wide variations in oil pressure that would otherwise occur.

The burner shown in Fig. 9 is the same as that shown in Figs. 1 to '7 inclusive except that the regulator that compensates for variations in line voltage is omitted and the outlet of the pump is connected by a length of copper tubing IN to one end of the tube 86 which carries on its other end the atomizing nozzle 9. Also, the pump, at its outlet end, is somewhat differently constructed, as will be explained. Variations in line voltage may be prevented from causing substantial variations in oil pressure by any suitable electrical regulator which will function to rdnaintain constant current in the circuit of coil The electromagnetic pump is essentially the same as before but the chamber 65 and resilient member 69 have been replaced by a diaphragm I22 and a chamber I23, formed in the pump body I24 above the diaphragm and in communication with the outlet of the pump. As shown the marginal portion of this diaphragm is rigidly held by clamping it between a cap I25 and the body, the cap being suitably secured to the body as indicated. The upper face of the cap has a shallow conical recess I25 therein located immediately below the diaphragm. The cap is formed for mounting in the lower resilient grome met 37 in the same way that the lower portion of the pump body 3! of Fig. 2 was formed. The lower end of the member 44 stops short of cham-, ber I23 and the plug l2'i, that is threaded into the lower end of member M to provide a seat for the spring 6! of the check valve til of the pump, has a passage [28 therethrough to connect the pump outlet to the chamber H23. The pump outlet passage 64 connects directly with the copper tube I21. Qtherwise the pump is constructed and operates as heretofore described.

As one suitable example, the diaphragm I22, herein shown, is made of brass, has a thickness of .009" and the circular area that is exposed to oil pressure is 1 4" in diameter. The lower chamber I26 has the same diameter and its maximum depth is .027. The outlet of the pump is connected to the rigid nozzle supporting tube 86 by g" copper tubing which has a length of 22 The operation of the electromagnetic pump, when its outlet is connected directly to the inlet of an atomizing nozzle of the mechanical or high-oil-pressure atomizing type, without any substantial length of intervening conduit and Without the pulsation-modifying means of this invention is illustrated in Fig. 11. The graph there shown is a tracing from the screen of an oscilloscope, arranged to show the oil pressure at the inlet of the atomizing nozzle. The nozzle used was one rated for 1 gallon per hour at pounds per square inch. As will be seen, the pressure rises sharply on the pressure stroke, as indicated by the part I35! of the graph, from a minimum of 58.8 p. s. i. to a maximum of 141.2 p. s. i. and then decreases on the suction stroke of the pump, as indicated by the part It! of the graph, to the aforesaid minimum. The very steep rise in pressure results in a severe impact, which tends to cause vibration in parts attached to the pump. A very wide variation in oil prespurpose.

11 sure is produced, in this case plus or minus 41.2 from the average pressure of 100 p. s. i. indicated by the line I32 of the graph, or a total variation of 82.4 p. s. i. In particular, the minimum instantaneous pressure values are too low for producing What may be called a safe stable spray from a nozzle of the type described, where atomization is affected by the action of centrifugal force on the release of a very rapidly whirling oil stream. Merely-to connect a mechanical atomizing nozzle directly to the outlet of the pump will not produce results, which are satisfactory for commercial use.

It is necessary, as a practical matter, to provide in an oil burner between the outlet of the pump and the atomizing nozzle a conduit of substantial length, and, usually, tubing which is somewhat flexible is used for the purpose because it readily be bent to the form required. Usually, copper tubing is used for the The use of such tubing has an adverse effect on the operation of the pump and nozzle. Harmonics are produced in the pressure wave. Increases in length of the tubing cause resonance at decreasing orders of frequency. The spread between maximum and minimum instantaneous pressures increases with increases in length of the tubing. Fundamental resonance occurs with a tubing length of about feet and the pressure variations then are substantially plus or minus 100%. Fig. 12 shows what occurs with the use of a inch length of fa" copper tubing. The

graph 133 shows a transition between the fourth and third harmonics with the wide spread in pressure variations of plus or minus 55.3%. The dotted line ltd is the estimated 60 cycie fundamental wave.

In Fig. 13, is shown the pressure wave as pro-- duced by the pump of Fig. 10, as above defined, and a 22 length of f g inch copper tubing between the pump outlet and the nozzle, which is rated at 1 gallon per hour at a pressure of 100 pounds per square inch. The diaphragm i522, having the dimensions above set forth, modifies a pressure wave very similar to that shown in Fig. 12 so that the pressure variations are substantially reduced to plus or minus 15.5% and in particular the minimum pressures are maintained well above the critical pressure at which a safe stable spray would be formed, as for er:- am'ple 65 to '70 pounds per square inch. The pressure wave !35 has three harmonics but their amplitude has been very greatly reduced. The dotted line E38 represents the estimated 6-0 cycle fundamental wave.

The diagrams of Figs. 11' and 12 illustrate operations of the electromagnetically-operated pump that are unsatisfactory for the purpose or" producing a satisfactory spray from a nozzle of the mechanical or pressure-atomizing type. Fig. 13 clearly shoWS how the diaphragm 22 renders the operation of a high-frequency reciprocating-piston pump of the class described suitable for use as an oil supply means for a mechanical atomizing nozzle. The member 69 and chamber 65 will function in a similar way. The output of the pump normally is in the form of a saw-toothed pressure wave such as shown in Fig. 11 having amplitude which is excessive for the purpose and, in particular, minimum pressure values below those at which a safe and stable spray can be produced. The condition is made worse as shown in Fig. 12 by the use of the conduit that is necessary to connect the pump and nozzle. The difiiculty is thought to be due in duit, presenting considerable volume between the pump andnozzlaand in part to the elasticity of the conduit itself. Elasticity at the outlet of the pump absorbs some of the vibrations from the severe impacts of the pressure strokes of the pumps and limits the adverse effects that would otherwise occur in the conduit intervening between the pump and nozzle. Controlled elasticity at the outlet of the pump is preferred. Elasticity, which is distributed along the conduit or at the nozzle is not as good because it tends to prevent the sharp cut-oil? that is desired, when the power to the pump is cut-off, in order to prevent afters'quirt at the nozzle. The diaphragm I22 has been shown to provide the amount of elasticity located at the right place to smooth out the pressure wave of the pump and maintain the instantaneous minimum pressure values well above the critical pressure at which a safe and stable spray can be produced by the nozzle.

The invention thus enables a high-frequency reciprocating-piston pump to be used as a means of supplying liquid to a mechanical atomizing nozzle and very important advantages to be se cured without the accompanying disadvantages; and even dangers, that otherwise might follow from low instantaneous pressure values and the resulting failure of the nozzle to produce an effective spray.

What is claimed is:

1. In an oil burner, an air-supply fan, a casing for the fan having inlet and outlet openings, a tube connected at one end to the outlet opening and conducting the air for combustion, av motor for driving the fan, a pressure-atomizing nozzle in said tube near the other end thereof, a re ciprocating-piston oil-supply pump, a conduit connecting the pump to said nozzle, an alternating-current electromagnet connected to reciprocate said piston at the frequency of the alternating current, said pump having two spaced parallel shoulders and cylindrical hubs extending in coaxial relation in opposite directions from said shoulders, grommets of rubber-like material one encompassing each hub and abutting the adjacent shoulder, and a support on said casing having spaced parallel outwardly-projecting arms supporting said grommets one in each.

2. In an oil burner, an air-supply fan, a casing for. the fan having inlet and outlet openings, a tube connected at one end to the outlet opening and conducting the air for combustion, a motor for driving the fan, a pressure-atomizing nozzle in said tube near the other end thereof; an oil supply pump comprising a body having a cylinder with an inlet and an outlet, a piston reciprocable in said cylinder, a valve for closing the outlet, and a spring tending to hold the valve closed, a conduit connecting the outlet or the pump to said nozzle, an alternating-current electromagnet connected to reciprocate said piston at the frequency of the alternating current, said pump having two spaced parallel shoulders and cylindrical hubs coaxial with said cylinder and extending in opposite directions from said shoulders, two grommets of rubber-like material one encompassing each hub and abutting the adjacent shoulder, and' a support on said casing having spaced parallel. outwardly-projecting arms supporting said grommets one in each.

3. In an oil burner, an air-supply fan, a casing for the fan having inlet and outlet openings, a tube connected at one end to the outlet opening and conducting the air for combustion, a motor part to the compressibility of the liquid in a con for driving the fan, a pressure-atomizing nozzle in said tube near the other end thereof, a reciprocating-piston oil-supply pump; a conduit connecting the pump to said nozzle, an alternatingcurrent electromagnet connected to reciprocate said piston at the frequency of the alternating current, said pump having two spaced parallel shoulders and cylindrical hubs extending in coaxial relation and in opposite directions from said shoulders, grommets of rubber-like material one encompassing each hub and abutting the adjacent shoulder, each grommet having in its periphery a circumferential groove, and a support on said casing having spaced parallel outwardly projecting arms each having a semi-circular edge engaged in one part of said groove, a member hinged at one end to the outer end of each arm and having a semi-circular part engaged in another part of said groove, and a fastener for holding the other end of each said member to its arm.

References Cited in the file of this: patent UNITED STATES PATENTS Number Name Date Waters Apr. 13, 1886 Serve Nov. 23, 1897 Meyers Feb. 5, 1924 Persons Dec. 29, 1931 Pirsch Jan. 10, 1933 Clarkson Aug. 22, 1933 Rodler Apr. 20, 1937 Holthouse June 16, 1942 Bremser Sept. 4, 1945 Holthouse Aug. 27, 1946 Pinkerton et a1. Oct. 28, 1947 Dickey et al June 7, 1949 Rosenthal Sept. 13, 1949 Simmons Jan. 17, 1950