US2575074A - Dual pump - Google Patents

Description

Nov. 13, 1951 E. J. 'SENNINGER DUAL PUMP Filed March 27, 1946 4 Sheets-.SheetA 1 Nov. 13, 1951 E. .1. SENNINGER 2,575,074

DUAL PUMP Filed March 27, 1946 4 Sheets-Shee't 2 Nov. 13, 1951 E. J. SENNINGER DUAL PUMP 4 Sheets-Sheet 4 Filed March 27, 1946 Patented Nov. `13, 1951 DUAL PUMP Earl Joseph Senninger,` Chicago, Ill., assignor to Sanniyer Corporation, a corporation of Illinois Application March 27, 1946, Serial No. 657,359

My. invention-relates to pumping devices for use in apparatus wherein two-fluids are pumped concurrently, with specialreference to such apparatus in which one fluid is of gaseous character and the other fluid is a liquid.

While the invention is applicable broadly to dual pumping tasks and is advantageous in various apparatus for'spraying mixtures of liquids and gases, such as paint mixtures, the invention b being initially embodied in an apparatus for burning liquid fuels. This initial embodiment will be described for the purpose of the present disclosure, since such a description will provide adequate guidance for applying the invention wherever it may have utility. Y

Oneof the important objects of my inventio l to provide a dual pump in which one pumping mechanism acts on non-compressible iluid'and a second pumping mechanism compresses a compressible fluid inA such manner that the heat of' oompression generated by the second pumping mechanismmay be transferred to the ilrstf-mentioned fluid for useful purposes. In the present embodiment of the invention that useful purpose is to pre-heat the fuel oil prior to delivery of the fuel oil to the burner nozzle.

In the preferred practice of my invention the heat of compression generated in the dual pump is employed to lighten the preheatlng burden that is imposed onan electrical heater in` the fuel oil line. l In a modified or alternate practice of my invention, however, the preheating of the fuel oil is provided primarily by the heat of compression generated in the dual pump, and the electrical heater on the fuel line is employed only temporarily in an automatic manner at the beginning of a period of operation.

With further reference to the construction of the dual pump, one of my objects is to provide a structure that may be readily dismantled for inspection, servicing or repairing, with special reference to the oil pump. It is contemplated that the oil pump will be readily dismantled without disconnecting or opening any part of the oil line in the system, and that such dismantling will not only make the interior of the oil pump accessible but will also expose for inspection a seal that is placed between the two pumps. This object is obtained by connecting the oil line on the air pump 'casing and by mounting the oil pump in a removable manner on the side of the air pump casing, .with suitable intake and discharge pas- 'sages provided in the air pump casing for the oilv pump.l The seal between the two pumps is mounted at or near the juncture of the oil pump with the air pump casing. g K

Certain objects of my invention relate to the construction of the seal between the two pumps, it being my purpose to provide an e'ective seal 2 chamber wall. In this regard a feature of the invention is the employment of rings oi rubber, or the like, embracing the actuating shaft, which rings are circular in cross-section so that in re, sponse to fluid pressure in one direction longitudinally of the shaft the rings will tend to roll along the shaft into desired sealing positions.

Other objects of my invention relate to the construction of the air pump per se. It iscontemplated that the air pump will be of a suitable chambered construction .whereby the oil may ,ow through the air pump structure for receiving heat generated by the air pump. In my preferred construction the casing i'or the air pump is constructed in the manner of a Jacket to provide heat exchange chambers for the iiowing oil. Thus the air pump by generating heat of compression supplies heat for raising the temperature of the oil and, conversely, the oil owing through the jacketed casing of the air pump serves as a cooling medium to prevent overheating of the air PllmlL A group of objects of my invention relating to the oil pump, per se, includes the following: To provide a novel arrangement in which two piston members aiord four piston heads to minimize the pulsations in the oil system; to provide` a novel arrangement of two piston members in which two pairs of piston heads are interconnected, respectively, by two offset webs, with the webs in overlapping. sliding relation for certain advantages; to provide an overlappingrelationship between the two piston members whereby the amount of now or displacement movement by the four piston heads may be governed by a single eccentric control; to provide what may be termed i dove-tailed relationships in the configuration of the four piston heads thereby to increase the freedom of the piston heads for inward movement relative to each vother for the purposeof achieving a relatively wide range of volume adiustment in a small compact oil pump; .and to provide, in such a construction, an eccentric control that is movable not only through a range of eccentric positions but also to a concentric position wheredrawings.

In the accompanying drawings, whichare to be regarded as merely illustrative:

Fig. 1 is a diagram of the system with 'parts displaced in such a way as to reveal an organic whole in one figure;

where an actuating shaft extends through a oo Fig. 2 is a longitudinal sectional view of the preferred form of my dual pump taken on the line 2-2 of Fig. 3;

Fig. 3 is a transverse section taken along the line 3-3 of Fig. 2. with certain walls broken awa Fixg. 4 is a diagrammatic view indicating the stages by which the ltemperature of a liquid is raised in a preferred practice of my invention;

Fig.- 5 is a transverse section taken as indicated by the line 5-5 of Fig. 2;

Fig. 6 is an elevation of two cooperating piston members employed in a liquid pump;

Fig. 7 is a section taken as indicated by the line 1-1 in Fig. 6;

Fig. 8 is a transverse section taken along the line 3-3 of Fig. 2;

Fig. 9 is a transverse section taken along the line 3-9 of Fig. 2; and

Fig. 10 is a portion of a wiring diagram to indicate a modified practice of the invention.

General description In the diagram shown in Fig. 1 the main housing I8 provides a tank or reservoir I I for lubricating oil, a chamber I2 for primary or atomizing In the diagram in Fig. 1 a number of partsV that are actually in the chamber I2 are, for the purpose of description, shown displaced downward and to the left. Among these displaced parts are a primary air supply line or tube I1, a nozzle I8, an oil supply line I9, a heater associated with the oil supply line I9, and a pair of electrodes 2| associated with the nozzle for igniting the mixture of oil and air in starting the burner. The main housing I8 serves as a support for an electric motor 22 which drives a secondary air fan or blower 23, an air pump 24 for supplying primary air to the nozzle, and an oil pump 25 for supplying fuel oil to the nozzle, these three driven devices being shown spaced apart on the same axis.

As will be discussed in detail later the present invention is directed primarily to the combined construction of the air pump 24 and the oil pump 25.

The secondary air fan or blower 23 takes air through the slotted side wall 26 of the fan casing I5 under control of a rotary shutter 21 and delivers the air through the draft tube I6 around the mixture of oil and air discharged from the orice 28 of the nozzle I8. The volume is varied by adjusting the rotary shutter 21.

The primary or atomizing air pump 24 takes air in through aperturesl29 and delivers it through a pipe 39 into the upper portion of the main housing through the filter I3. The lubricating oil tank II is connected near the bottom by a pipe 33 with the primary air pump 24, and by reason of the air pressure within the chamber I2 oil from the supply 3I in the tank'l I is continuously delivered to the air pump. As a result this pump delivers a mixture of air and oil, or air and oil foam. to the pipe whereby the bronze wool in the lter I3 is made to serve as a combined oil separator and air cleaner and the lubricating oil collected there drops down over the outside of the draft tube I8 to return to the tank II. The lter I3 is separated from the filter I4 by a partition 34, and the air compressed in the chamber I2 passes up through a second mass of bronze wool in the iilter I4 before entering' the pipe 32.

In practice the apparatus is so designed that a normal pressure of from five to thirty pounds. for example, may be built up and maintained in the chamber I2. The pressure in the primary or atomizing air system is regulated by ahy-pass 35 connected across the inlet and outlet of the pump 24 and controlled by an adjustable valve 36. In this diagram the by-pass is shown as external piping, butin practice may be incorporated in the body or casing of the pump. if desired. I

Oil for fuel ,is stored in a suitablefuel supply tank (not shown) and is led from the supply tank through a pipe 33 to the oilvpump 25. Fig. 1 shows the pipe 38 entering the air pump 24 instead of the oil pump 25, but, as will be explained in more detail later, concealed passages in the air pump 24 lead to the intake of the oil pump 2l and other, concealed passages lead from the delivery side of the oil pump through the structure of the air pump to the oil supply pipe 39.

Where gravity feed cannot be used, an auxiliary pumpingequipment 31 should be provided to boost oil from the supply tank to the oil pump.

The oil pump 25 delivers the fuel oil through the supply pipe 39 and the previously mentioned pipey I9 to a three-way valve that is concealed in the nozzle I8. The three-way valve is governed by a pressure-responsive actuator or automatic valve control 4I. At the idle or nonoperating position of the .three-way valve the end of the oil supply pipe I9 at the nozzle I3 is placed in communication with a by-pass pipe 42 that leads from the nozzle I8 back to the fuel oil supply tank. In response to rise in pressure in the air supply pipe 32 the automatic control 4I moves the three-way valve to its normal operating position, thereby to place the end of the oil supply pipe I9 at the nozzle I8 in communication with the nozzle orice 28.

The preferred construction of the automatic control 4I and the three-way valve and the nozzle I8, together with other associated parts in the draft tube I6, is disclosed in detail in my copending application Serial No. 657,358 now Patent 2,489,823 dated November 29, 1949, entitled Liquid Fuel Burner System, iild concurrently herewith.

When operation of the described arrangement is started, oil discharged from the pump 25 through the supply pipes 39 and I9 is initially by-passed at the nozzle back to the supply tank through the by-pass pipe 42. As soon as suiilcient pressure is built up in the fluid course including the air chamber I2 and the air supply pipes 30 and 32 to insure proper delivery of primary or atomizing air to the nozzle I8, the pressure-responsive actuator 4I will react to the rise in air pressure by operating the three-way valve in the nozzle I8 to cut off the by-pass pipe 42 and to open communication to the nozzle orifice I8,

whereupon a fuel mixture of .oil and air is discharged in spray form from the nozzle for combustion. When for any reason the air pressure in the chamber I2 drops below that for which the device is designed and adjusted, the pressure-responsive actuator 4I will operate the three-way valve in the nozzle to cut off oil flow to the nozzle oriiice 28 and to cause the oil discharged by the pump 25 to be returned to the supply tank through the by-pass pipe 42.

Any one of the many types of oil burner controis may be used with this system and none will be described in the, interest of brevity. It will be sufficient to refer to Oil Heating Hand Book" by Hans Kunitz, second edition, and The Starbuck Oil Burner Manual, 1941.

Electric powerfor the liquid fuel burner system described may be taken from the house line 45, and the apparatus shown in the diagram will be.understood from the following description of the operation.

When the room thermostat or boiler control 4B calls for heat, Minneapolis-Honeywell R117 relay 41 will be energized and close an electric circuit to the oil heater 20 and the ignition transformer 4l. After a delay period, for example twentyfive seconds. switch 48 will close the circuit to motor 22, which will start the secondary air fan or blower 23, the primary or atomizing air pump 24, and the oil pump 25. While the pump 24 is building up the necessary pressure in the chamber I2, oil from the pump 25 is recirculated through the by-pass pipe 42 and the heater 20 is conditioning the oil in the pipe I9 and warming up the associated parts of the burner. When the pressure in chamber I2 reaches the selected amount the pressure-responsive actuator 4I will operate the three-way valve in the nozzle to cut of! the by-pass pipe 42 and permit mixed oil and air to be discharged through the nozzle orifice 2B. As the mixture of air and atomized heated oil is discharged from the orifice 28 of the nozzle sparks from the electrodes 2i ignite it, and the iiame is further fed by the supply of secondary air delivered by the fan or blower 23 through the draft tube I6. After a short interval, relay d1 will shut off the current to the ignition transformer 49. The resistance of the heater element it increases with the rise in temperature and the wattage drops to the selected limit' for the particular design.

Mention of Minneapolis-Honeywell R117 relay is merely by way of example. Many other controls can be used, and-some other controls must be used when the fire adjusting apparatus, later described. is associated with the burner.

Modulating the fire The operation of the apparatus described is preferably modified by means to increase the fire after it is started and then to modulate the fire according to the demand for heat. One embodiment of means to that end includes an air motor comprising a cylinder 50, equipped with a piston 5I whose piston rod 52 runs through a guide 53 and has one arm 54 connected by a link 55 with the rotating shutter 21 of 'the secondary air fan or blower, and another arm 56 connected by a link 51 with a lever 58 on the oil pump 25 by which the capacity of the oil pump may be adjusted and enlarged as the shutter 21 is opened to increase the delivery of secondary air by the fan or blower 23.

The piston 5| is normally urged to the position shown by a spring 59, and its limit in that direction is determined by a low re stop 60, its limit in the other direction being determined by a high fire stop 6I, both adjustable on the piston rod 52 and made fast by set-screws or the like.

In order to move the piston against the resistance of spring 59, air from the chamber I2 is conducted by a pipe 62 and delivered to a head I chamber 63 in the air end of the cylinder 50 from which chamber the air passes by a port 64 into the cylinder and exerts its pressure against the piston 5I. The length of the pipe 62 and the ad- Justment of a needle valve will make the dow of air involve the time interval desired for response to change in demand, and the supply of air and oil will be increased or decreased in relation to the pressure permitted to build up against the piston head, this function, however, being limited by the adjustment of low re stop 60 and high fire stop 6I. In some designs the length of the pipe 62 will have a negligible eifect and the control will be eiected chiefly by adjusting the needle valve 55.

With this arrangement the burner will start with a very small flame and gradually build up to the required size, as determined by the design and adjustment, and will stay there until the burner is stopped, at which time the spring will force the piston to low fire position. During the movement to low fire position the air in the cylinder will escape through the orifice 66 and the check. valve 61 back to the chamber I2 and be discharged through the nozzle. Y

It is preferable, however, to add a, modulating control, one embodiment of which includes a pneumatic temperature or pressure device 68 connected with the cylinder 50 by a pipe 69. When the temperature or pressure of the device 68, or the space to which it is subject, reaches the point at which it is set, the arm 1I of the device 58 will uncover an orifice 10 in the pipe 69. allowing some air to escape, thus lowering the pressure in the cylinder 50 and allowing the piston to move toward the air end of the cylinder under the action of the spring 59. reducing the supply of secondary air and oil. The piston will adjust itself to some point between high fire and low fire positions, depending on the demand indicated by the arm 1 i. If the temperature or pressure at the device 68 should drop or increase, the port 1i) will be opened or closed correspondingly, and hence the re will be adjusted to correspond with the demand.

It will lbe noted in Fig. 1 that the pipe 52 is connected to the head chamber 53 immediately above the check valve 51 and well below the port 64 and the needle valve 65 associated therewith. The `advantage of this particular. arrangement is that any oil or foreign particles carried into the head chamber 63 through the orice 66 will be carried directly into the pipe 52, not into the region of the needle valve 65, so that there will be no tendency for the needle valve 65 or the port 64 to be clogged by such reverse iiow.

The device 68 may be any pneumatic control that will open a port on an increase of temperature or pressure to bleed the air from the line 69 to the atmosphere, or close the port on a decrease of temperature of pressure, such. for example, as Minneapolis-Honeywell L-O92D. These devices are available in a number of scale ranges and may be used as a warm air control mounted in the air stream, or as an immersion aquastat inserted in the liquid to be controlled, or as a steam pressure control mounted in the boiler water just below the water line. The boiler water temperature changes with the steam pressure in accordance with familiar steam tables. As these devices and their applications are familiar, specific disclosure is omitted in the interest of brevity.

General arrangement for preheatz'ng fuel oil It is essential that the fuel oil supplied to the burner nozzle be preheated, and a feature of my dual pump construction is that one pump mechanism therein functions to compress the air re- 7 quired for the spray action at the nozzle while the other pumping mechanism functions to pump the fuel oil to the nozzle-the arrangement being such that the heat of compression generatedin the air pump mechanism is transferred to the liquid handled by the fuel pump. It will be apparent to those skilled in the art that the necessaryl heat transferring relationship between the twof pumping mechanisms may be achieved by many different constructions. The relationships involved in the preferred practice of my invention, however, are indicated diagrammatically in Fig. 4.

Fig. 4 shows diagrammatically the air pump 24, in whichheat of compression is continuously generated during normal operation of the apparatus. 'I'he previously mentioned pipe 38 for carrying oil from the supply tank to the pump 25 communicates with what may be termed a heat-transfer or heat exchange chamber 80 or jacket chamber incorporated in the casing of the air pump 24. From the heat-transfer chamber 80 the oil is conducted to the intake side of the oil pump 25, and on the delivery side of the oil pump is discharged into a second heattransfer or heat exchange chamber or jacket chamber 8| incorporated in the construction of the air pump 24. From the second heat-transfer chamber 8| the previously mentioned pipe 38 leads to the fuel burner nozzle I8, but before the flowing oil reaches the nozzle it passes through the previously mentioned heating coil 20.

It is apparent that the described arrangement employed in the preferred practice of my invention provides for raising the temperature of the fuel oil in four stages. the first stage of temperature rise being in the heat-transfer chamber 80; the second stage being in the oil pump itself,

Where the work done on the oil has a tempera-- ture increasing effect arising from friction among the oil particles; the third stage being in the heat-transfer chamber 8|, and the flnal stage being provided by the heater'20.

Air pump construction motor 22, extends through both the end cap 83 y and the connecting body 85.

The shell 82 of the air pump has an inner cylindrical wall 81 eccentric to the shaft 86, and said shell also forms an upper filter chamber 88 containing a mass of bronze wool 80. The sh'ell 82 of the air pump also forms two previously mentioned heat-transfer chambers 80 and 8|, the two chambers being on opposite sides of the air pump and being separated at their lower ends by an inner wall 9|. As best shown in Fig. 3, the heat-transfer chamber 80 h s an intake port connected to the previously m ntioned oil pipe 38 and an outflow bore 88 (Fig. 3) to the connecting body 85. In like manner the other heattransfer chamber 8| has a delivery port connected to the previously mentioned pipe 38 and an inflow bore 84 (Figs. 2 and 3) to the connecting body 85. If desired, the oil line 38 may be connected to the lower threaded opening 84 in the heat-transfer chamber 80 for better oil circulation through the chamber 80, but tests indicate that such a change is not necessary.

'Ihe filter chamber 88 is covered by a removable cap 82 or closure that is releasably held in place by a cap screw 83 threaded into a boss 88. Air taken in by the pump 24 enters the filter chamber 88 through the previously mentioned apertures 28 in the' filter chamber cap 82 and leaves the filter chamber through two recesses 81 shown in dotted lines in lFig. 3. Therais one such recess 81 on each side of the boss 85 in the filter chamber, and each of these recesses communicates with an intake bore 88 leading to the corresponding end face ofthe casing shell. Near the` two intake bores 88 is a single parallel discharge bore |00 that extends from end face to end face of the casing shell 82, which bore communicates with a 'single bore or passage |0| leading to the previously mentioned pipe 30 for delivering compressed air from the pump to the previously mentioned chamber |2. A suitable check valve |04 is incorporated in the passage |0| to prevent reverse flow of air from the pipe 30 to the pump.

Mounted on the shaft 86 inside the chamber formed by the cylindrical wall 81 of the pump is a suitable rotor |02, the rotor being eccentric to the cylindrical wall and in sealing proximity to the upper portion of the wall, as best shown in Fig. 3. Slidingly mounted in suitable radial slots |03 vin the rotor |02 are suitable pump blades |05, which blades are thrown outward by centrifugal force and therefore tend to follow closely the cylindrical wall 81. Preferably the pump blades |05 areiformed with suitable grooves |06 on their leading faces.

The end cap 83, which carries a suitable bear.'- ing |01 for the shaft 86. is mounted on the shell 82 by suitable screws |08, together with l sealing gasket, and has suitable grooves on its inner face forming a curved intake passage i0 and a curved discharge (Fig. 9). The curved intake passage ||0 communicates at its upper end with the corresponding previously mentioned bore intake 88, and the curved discharge passage communicates at its upper end with the corresponding discharge bore |00. As best shown in Figs. 2 and 9, the end cap 83 has formed therein a suitable passage ||2 which communicates with a passage ||3 in the pump shell 82 whereby lubricating oil from the previously mentioned lubricating oil pipe 83 may reach the interior of the air pump.

A suitable bushing ||5, carrying a packing ring ||6 for the shaft 88, is threaded onto a tubular extension ||1 of the end cap 83 to form therewith a suitable chamber ||8 to serve as an oil sump on the outer side of the bearing |01. Lubricating oil under pressure is continually urged outward along the shaft'l through the bearing |01 for lubrication of the bearing and the excess oil tends to accumulate in the sump II8. To prevent excessive accumulation of oil in the sump ||8, the end cap 83 has formed therein a suitable passage |20, shown in dottedlines in Fig. 9, which passage leads from the oil sump to the intake zone of the air pump. In the construction shown, the passage |20 ends in the curved intake passage I I0.

The connecting body 85, which carries a suitable bearing 2| for the shaft 86, is mounted on the pump shell 82 by suitable screws inserted in holes |22 (Fig. 5) together with a suitable gasket, and, like the end cap 83, has formed on its inner face a curved intake passage ||0 in communication with one of the previously mentioned intake bores 88 and a curved discharge passage lll in communication with the previously mentioned discharge bore |00. The connecting body 85 also has a suitable passage |23, similar to the previously mentioned passage H2 (shown in dot-l ted lines in Fig. 2), for conducting lubricating oil from the pipe 33 to the interior of the pump.

One of the features of the present construction is a novel seal housed by the connecting body 85 for the dual purpose of preventing air leakage from the air pump 24 and of cutting off fluid communication along the shaft 86 between the air pump and the oil pump 25. As shown in Fig. 2, a suitable metal ring |25 is mounted on the outer face of the connecting body 85 by suitable screws V|26, the metal ring being mounted on the connecting body in a fluid-tight manner to serve in effect as part of a chamber wall through which fluid flow is to be prevented.

Surrounding the shaft 86 adjacent the metal ring |25 is a sleeve 21 having a cylindrical wall |28 spaced substantially from the periphery of the shaft and having a radial end wall |30 extending inward therefrom toward the shaft in abutment with the ring |25. The sleeve 21 is freely slidable longitudinally of the shaft 86 but is engaged with the shaft to rotate therewith. The required interengagement may be provided by a wire ring |3| embracing the sleeve |21, the `wire ring having an end extending radially inward, as indicated at 32, to engage a short keyway 833 in the shaft. Suitable means to continually urge the sleeve H21 against the stationary ring 25 may comprise a circumferential series of helical springs |35 seated in a ring |36 that rotates with the shaft 55, the ring l35 being hacked against a shoulderl |31 on the shaft. Preferably the ring |25 is of relatively soft material, auch as bronze, while the sleeve |21 is of' harder material, such as steel. Such a combination of materials results in an effective fluid seal by the two contacting relatively rotating faces.

To prevent fluid leakage inside the sleeve |21 at least one packing ring |38, and preferably two such packing rings as shown, are mounted on the shaft 86 inside the sleeve. Each of these packing rings |38 is made of rubber, or similar elastic material, and is of circular cross-section, as shown, so that each ring tends to travel along the shaft by a rollingr action in response to fluid pressure longitudinally of the shaft. In this in- Stance the prevailing pressure is outward from the air pump 24, so that the two packing rings |35 are urged toward the radial end wall |30 of y the sleeve 21. It is contemplated that the two packing rings |38 will form an effective seal around the shaft because of their tight fit against the shaft and their contact with the sleeve |21. Preferably both of the rings have an unrestrained outside diameter slightly greater than the inside diameter of the sleevel |21, so that the rings are compressed in a fluid-tight manner by the circumferential wall |28 of the sleeve. In addition, the pressure contact of one of the. packing rings |38 against the end wall |30 of the sleeve lprovides `a fluid seal.

The connecting body 85 serves the various functions nf a casing member or end cap for the air pump 24, a casingV member or end cap for the oil pump 25, means for mounting the oil pump on the air pump, and .finally as means for communication between the oil pump and the previously mentioned heat exchange chambers 80 and 8| in the air pump. For the latter purpose the connecting body 85 has a peripheral enlargement |42 (Fig. 5), to accommodate an inclined intake passage (not shown) `for communication between the oil pump 25 and the heat exchange chamber 80, this passage registering with the previously `mentioned outflow bore 89 in the air pump shell. 'I'he connecting body 85 also has a second enlargement |40 for a similar passage |4| (Fig. 2) for communication between the oil pump and the other heat exchange chamber 8|, this similar passage communicating with the previ- `ously mentioned inflow bore 84 .in the air pump shell.

The operation of the air pump may be clearly understood from the foregoing dtscription. The valve 36 in the by-pass 35, shown diagrammatically in Fig. 1, is adjusted to maintain some selected normal pressure in the chamber I2 of the main housing, which pressure, for example, may be within the range of iive to thirty pounds.

A feature of the present form of the invention, however, is that the moving parts of the primary air pump 24 are dimensioned with such liberal clearances that plentiful lubrication of the pump interior is required to cause and maintain the selected normal pressure. By making the presence of a considerable amount of lubricating oil in the primary air pump 24 necessary to seal it and to give it the required capacity, it becomes impossible to run the pump long with insumcient lubrication, for as soon as the pressure in the chamber I2 drops below that required the supply of lubricating oil provided through the pipe 33 is cut off and a control of any one of the customary forms will put the apparatus on safety and shut the burner down entirely. If internal lubrication of the pump is non-existent, or is insuiiicient to adequately seal the clearance spaces, the pump will function at a lower level of efllciency, the pressure in the chamber i2 then being 'wo low for the valve control 4I to maintain fuel oil flow to the nozzle but high enough to force lubricant through pipe 33 to the air pump.

The required liberal clearance may be provided between any of various cooperating surfaces. Thus the clearance may be at the side edges of the blades |05 or between the faces of the rotor and the end cap 83 and the connecting body 85, or between the faces of the blades and the corresponding faces and walls of the slots |03 in the rotor. The provision of such clearance requires only the ordinary skill expected in this art, especially since the pressure created\by the pump running without lubricant is not critical. For example, suppose the valve control 4| is so adjusted as to cut oil? uid flow to the nozzle whenever the air pressure drops to five pounds. A minimum pressure of only one pound will lift lubricating oil through the pipe 33 to the air pump 24. Thus the clearance in the working parts of the air pump may be such as, in the absence of lubricant, to drop the pressure of the air pump to any value between one and iive pounds.

Oil pump construction The oil pump 25 has a casing comprising a body or shell |45 and an outer end cap |46, the previ ously mentioned connecting body 85 serving as a second end cap for the casing. Suitable long screws |41 serve not only for removably mounting the oil pump on the air pump, but also to interconnect in a fluid-tight manner the shell |45 of the oil pump casing and the end cap |46. Suitable gaskets make the connections air tight.

The body |45 of the oil pump has a cylindrical liner |50 defining a pump chamber and in which is mounted a suitable shaft or rotor |5|`, the line!l having an intake port |53 (Fig. 5) and a discharge aand/4 port |52. 'Ihese two ports |52 and |53 are in the form of extensive slots. The intake port |53 in the liner communicates withA an intake passage comprising a radial bore |51 and a longitudinal bore |58, the longitudinal bore |58 communicating with the previously mentioned intake na ssage (not shown) in the peripheral enlargement |42 in the connecting body 85. In like manner the discharge port |55 in the liner |50 communicates with a dischargeor delivery passage comprising a radial bore |55 and a longitudinal bore |56 (Fig. 5), the longitudinal bore communicating with the previously mentioned delivery passage |4| through the connecting body 85 to the heat exchange chamber 8| in the air pump 24.

The rotor |5| is operatively connected with the shaft 86 in any suitable manner that will permit the oil pump to be readily disconnected from the air pump. In the present construction the operative connection is provided by a small shaft Acoupler |60, having one tongue |6| extending into a slot |62 in the rotor and having a second tongue perpendicular to the first tongue, the second tongue extending into a diametrical slot in the end of the shaft 86.

The rotor |5| has a circular axial opening |65 from one end. and two diametrical bores 180 apart intersecting the axial opening |65, thus forming four pump cylinders |66 90 apart. The axes of the two diametrical bores are slightlv ofiset axially of the rotor. S'idinglv mounted in each of the two diametrical bores in the rotor is a piston member that preferablv is formed by cutting away the material of a cylindrical block in such manner as to provide two coaxial piston heads integrally interconnected by a suitable web. Thus. as bast shown in Figs. 6 and 7. there are provided two coaxial piston heads |61 interconnected by an offset web |68. and a second pair of coaxial piston hea ds |10 interconnected by a second oilset web I1 the operation of the apparatus.

It will be noted that the web |68 has a flat inner face |12 and the web |1| has a flat inner face |13, while the sides of each piston member adiacent its web has flat faces |15 of angular configuration. Preferably the recess in each cvlindrical block that forms the flat face of the interconnecting web is somewhat shorter than the recesses that form the sides of the web, so that in the finished construction each of the four piston heads |61 and |10 has a corner notch into which either one of the adjacent piston heads may dove-tail or nest, as indicated in Fig. 6. In practice the pistons do not actually come into such mutual nest. ing contact but do approach such contact, the dove-tail relationship and the relative narrowness of the piston webs thus permitting relatively extensive inward movement of the pistons relative to each other thereby affording exceptional range of radial piston movement.

When the two piston members are positioned with the corresponding piston webs |68 and |1| offset in the same direction, with the two webs in sliding contact with each other, the four piston heads |61 and |10 will form a rectangular pocket |16, as best shown in Fig. 5. It is possible for the four piston heads to form such a pocket because they all cut some radial planes of the rotor in common with each other. The pocket |16 may be termed a yielding pocket s'nce the four piston heads are free to move radially.'

Extending into the pocket |16 is a circular means |11 that is of a diameter to occupy substantially to full cross dimension of the pocket and in normal operation is positioned eccentrically of the rotor |5| to cause pumping action of the four pistons in a manner well known in the art. The circular means |11 may be aptly termed a volume control eccentric for the oil pump, the adjustment of which determines the rate of positive displacement by the pump to supply fuel oil to the nozzle I8.

One of the features of the present construction is that the eccentric control |11 is movable not only through a progressive range of eccentric positions but is also movable to a concentric position at which the oil pump will not pump any oil to the nozzle I8. By virtue of such a, construction the eccentric control |11 may be manipulated in the same manner as a valve, since it may be moved to a closed or no flow" position while the pump is operating, and may also be moved through a range of open" positions for different rates of oil flow.

Any suitable means may be employed to govern the position of the eccentric control |11 during In the present construction the eccentric control |11 is in the form of a cylindrical body with a diametrical slot |18 in its outer end, the cylindrical body being mounted in a movable base in the form of a metal block or disk |80. The disk |80, which has a diametrical guide slot |8| perpendicular to the previously mentioned slot |18, is movably mounted in a relatively large circular chamber |02 formed in the oil pump body |45, and is guided by a pair of suitable pins |83 that extend from the end cap |46 into the guide slot |8|. Preferably, but not necessarily, suitable yielding means is provided to urge the disk in one of its guided directions. For this purpose I show a suitable helical spring |85 seated in a hollow screw |86.

Mounted in a tubular extension |81 in the end cap |48 of the oil pump is a suitable control shaft |88, on the inner end of which is an eccentrically positioned linger that extends into the previously mentioned diametrical slot |18. It is apparent that rotation of the control shaft |88 will vary the position of the finger |90 in its eccentric orbit, and will thereby vary the position of the eccentric control |11 in the -flexible pocket formed by the four piston heads. As heretofore indicated, the range of adjustment thus provided includes a concentric position for the eccentric control |11.

The control shaft |88 is shown surrounded by suitable packing |9| that is held in place by a suitable gland |92. 'I'he gland |92 may be tightened down against the packing to create any desired degree of frictional resistance to rotation of the control shaft |88, and usually sufflcient friction will be provided to maintain the control shaft in any position of adjustment in opposition to the force exerted by the spring |85. The outer end of the control shaft |88 is flattened as indicated in Fig. 2 so that the previously mentioned lever 58 may be non-rotatably mounted thereon.

One feature of the described construction is the manner in which the piston heads are prevented from rotating about their own axes. As indicated in Figs 2, 6 and 7, the flat face |12 of the web |68 interconnecting the two piston heads |61 lies against the rounded side of the web |1| and thereby prevents rotation of the two piston heads 13 tion of the two piston heads |10 about their axis. 'I'hus the eccentric control |11 not only serves its normal control purpose but also serves to prevent rotation of the four piston heads about their axes.

The operation of the oil pump may be readily understood from the foregoing description. It is readily apparent that the fuel oil circulated by the pump is heated in the three stages exemplified diagrammatically in Fig. 4, as heretofore explained. Since during normal operation the heat of compression generated vby the air pump 24 is substantial, the burden placed on the heater 20 is much lighter than would ordinarily be required, and the heater 20 may be a relatively.

small coil. As a result the initial cost of the heater is lessened and the amount of electric current consumed for preheating the fuel oil is reduced.

It will be noted that simply removing the screws |41 permits the oil pump to be dismounted from the air pump, and that such dismounting does not involve the usual necessity of disconnecting pipes in the fuel oil circulation system. In this connection it will be noted that the rotor constitutes in eiTect a second shaft which operates the oil pump and is connected to the driving shaft 86 through the coupler |60. Such dismounting oi' the oil pump not only makes the interior of the oil pump accessible for inspection, repair or servicing, but also exposes the bronze ring |25 for servicing or inspection of the sealing means around the shaft 86 between the oil pump and the air pump.

Modified practice of the invention In a modified practice of the invention the heater 20 is employed only temporarily at the beginning of an operating period of the apparatus. the normal nreheatinn.r of the fuel oil over operating periods being by the heat of compression generated in the air pump 24. cates the changes in the electrical system of Fig. 1 that mav be made to carry out the contemplated modified practice.

Much of the arrangement shown in Fig. is unchanged from that shown in Fia'. 1. Thus a wire |95 from one side of the line 45 has a branch |96 to the ignition transformer 49. and a second branch |61 to one side of the previously mentioned motor 22. Likewise the wire |95 is connected to one side of a heating element |98 in the relav 48 that serves to heat the bi-metal element |99 therein. which bi-metal element controls a switch 200 in the relay. In the same manner as before a wire 202 connects the second side of the heating element |98 with one side of the main heater 29 for preheating the oil in the tube i9 leading to the nozzle I8.

The wiring diagram in Fig. 10 differs from the wiring diagram 5| in having the second side of the heater connected by a wire 203 with the wire 205 that returns from the ignition transformer 49 to the previously mentioned relay 41. Thus the heater '20 is placed in parallel with the ignition transformer 49. The diagram in Fig. 10 further differs in the addition of a switch 206 in parallel switch 200, the switch 206 closing in response to rise in pressure in the air course that supplies atomizing air to the burner nozzle. Fig. 10 shows a Sylphon 201 from which a pipe 208 extends to the air supply system. The pipe 208 may be connected, for example, to the previously mentioned air pipe 30 or to the previously men- Fig. 10 inditioned air pipe 32, or may be connected directly to the chamber I2 in the main housing.

'I'he operation of the modified system is as follows: When the room thermostat or boiler control 46 calls for heat, Minneapolis-Honeywell E1-l7 relay 41 will be energized to close an electric p circuit to the delayed action switch 48, thereby allowing current to iiow to the heater 20, the ignition transformer 49, and the heating element |98 that aiiects'the temperature of the bi-metalelement |99. After a delay of twenty-iive seconds, for example, the warping of the bi-metal element |99 against the switch 200 will close the switchv to energize the motor 22 for starting the secondary air fan or blower 23, the primary or atomizing air pump 24, and the oil pump 25. Thus the heater '20 is energized prior to energization of the oil pump and continues to be energized after the.

oil pump is started.

The rising air pressure caused by operation of the air pump 24 eventually causes the Sylphon 201 to close the switch 206, thus establishing a second path for current iiow to the motor 22 independently of the switch 200. A short time later the rise in the stack temperature causes the relay 41 to cut off the ignition circuit, and since the heater 20 is parallel with the ignition circuit the heater 20 is also cut off, and will remain out oil, during the rest of the combustion period.

Thus the heater 20 is energized for only a rela- -tively short initial period for starting the burner, and is automatically cut off as soon as the heat of compression generated by the air pump 24 is suiiicient for the normal required preheating of the oil.

This application is a continuation-in-part of my applications Serial Nos. 428,390 and 428,391, filed January 27, 1942. for Linuid Fuel Burner Svstem, and of my application Serial No. 428,392, filed on the same date, for Liquid Fuel Burner which have matured. respectively. into Patents Nos. 2,397,986. 2.397,987 and 2,397,988, all issued on April 9, 1946.

The four copending applications mentioned herein are made a part of the present disclosure by reference.

My description in specific detail of the preferred practice of the invention will suggest to those skilled in the art various changes and substitutions within the scope of the appended claims.

I claim as my invention:

1. In a dual pump, a iirst pump having a casing provided with a pump chamber having inlet and outlet ports, a first shaft extending into said pump chamber and having a pumping element associated therewith, said shaft passing through a side wall of the casing, a second pump adapted to be mounted on said side wall of the rst pump casing and having a casing provided with a pump chamber having inlet and outlet ports, a second shaft extending into said second pump chamber and having a pumping element associated therewith, said second shaft being in substantial alignment with said first shaft, a detachable coupling device between said two shafts whereby the two shafts are rotated in unison and may be readily disconnected, said first pump casing being provided with fluid inlet and outlet passageways which are adapted 'to be connected at one end by fluid connection means to a source of fluid for the second pump and a point of use for lsuch fluid. respectively, and to communicate at their other ends with said inlet and outlet ports, respectively,

of the second pump when the two pumps are mounted in juxtaposed relation, and readily detachable fastening means for securing the two pumps together, whereby the second pump may be removed intact from said rst pump by merely removing said fastening means and without disturbing said fluid connection means.

2. The combination set forth in claim 1 which includes a seal around one of said shafts to cut ofi communication between the two pumps along said two shafts, said seal being at a position on said one shaft to be exposed by the removal of said second pump from the casing of the first pump.

3. The combination set forth in claim 1 in which said fluid inlet and outlet passageways are in heat-exchange relationship with the rst pump chamber, whereby the fluid acted upon by the second pump is heated by the heat of compression of the first pump both before and after said iiuid passes through said second pump.

4. The combination as set forth in claim 1 in which said coupling device includes a slot in the end of one of said shafts and a mating rib on the end of said other shaft.

` EARL JOSEPH SENNINGER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,135,414 Vincent Apr. 13, 1915 1,541,768 Diller et al. June 9, 1925 1,592,024 Jennings July 13, 1926 1,886,751 Schreiber Nov. 8, 1932 1,923,600 Warner Aug. 22, 1033 1,968,023 Bijur July 31, 1934 2,009,137 Kleckner July 23, 1935 2,199,454 Andler et al May 7, 1940 2,397,986 Senninger Apr. 9, 1946 2,397,987 Senninger Apr. 9, 1946 2,397,988 Senninger Apr. 9, 1946 2,409,477 De Lancey Oct. 15, 1946 2,411,509 Endebak Nov. 26, 1946

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