US3312177A - Fuel pump arrangement for an oil burner - Google Patents

Description

April 4, 196 o. ECKERLE ETAL 3,312,177

FUEL PUMP ARRANGEMENT FOR AN OIL BURNER Filed April 22, 1965 4 sheets-sheeti- April ,1967 o. ECKERLE ETAL 3,312,177

FUEL PUMP ARRANGEMENT FOR AN OIL BURNER Filed April 22, 1965 4 Sheets-Sheet 2 /n u'anfors 0/70 ic/r'ek/e f/e/muf lde/b ek/ 76/ MM Q April 4, 1967 o. ECK ERLE ETAL FUEL PUMP ARRANGEMENT FOR AN OIL BURNER Filed April 22, 1965 4 Sheets-Sheet 5 FIG. 3

April 4, 1967 o. ECKERLEI ETAL 3,312,177

FUEL PUMP ARRANGEMENT FOR AN OIL BURNER 1 Filed April 22, 1965 4 Sheets-Sheet 4 FIG. 4

United States Patent Ofifice 3,312,177 Patented Apr. 4, 1967 3,312,177 FUEL PUMP ARRANGEMENT FOR AN OIL BURNER Otto Eckerle, 3 an! Bergwald, Malsch, Kreis Karlsruhe, Germany, and Helmut Weinzierl, Rastatt, Germany; said Weinzierl assignor to said Eckerle Filed Apr. 22, 1965, Ser. No. 449,940 Claims priority, ap lication Germany, Feb. 5, 1965, E 28.634 12 Claims. (Cl. 103-126) This invention relates to the fuel supply of oil burning furnaces, and particularly to a fuel pump arrangement for an oil burner.

The object of the invention is the provision of a fuel pump capable of high intake suction.

A corresponding object is the provision of a pump arrangement in which the intake conduits and associated elements are sealed against inward penetration of ambient air, and in which air or other gases entering the pump with the liquid fuel are promptly eliminated.

A further object is the provision of a pump arrangement in which flashback from the associated oil burner to the fuel system is reliably prevented when the pump stops supplying fuel to the burner.

In its more specific aspects, the invention is concerned with a fuel pump which is a gear pump having one internally toothed rotor and an externally toothed rotor of smaller pitch circle in meshing engagement, and it is an additional object of the invention to provide the closest possible clearances between the rotors and the associated stationary pump elements.

Yet another object is a pump arrangement of the type described which includes a simple and rugged valve simultaneously capable of maintaining a desired maximum pressure in the fuel delivered to the burner, venting air from the fuel, and automatically disconnecting the burner from the fuel system as soon as the fuel stream stops.

With these and other objects in view, as will hereinafter become apparent, the pump arrangement of the invention contemplates the use of a pump casing defining a cavity which is closed by a cover member secured to the casing, and which communicates with a suction conduit and a discharge conduit. Rotor means are movably arranged in the pump cavity for drawing a fluid into the cavity through the suction conduit, and for discharging the fluid under pressure through the discharge conduit. A cap member encloses an upwardly extending filter compartment about the pump cover. The suction conduit has an orifice in the topmost portion of the filter compartment. An intake is provided for admitting fluid to the filter compartment.

Other features and many of the attendant advantages of this invention will become readily apparent from consideration of the following detailed description of preferred embodiments relating to the annexed drawings in which:

FIG. 1 shows an oil burner pump of the invention in side-elevational section on the line II in FIG. 2;

FIG. 2 shows the pump of FIG. 1 in front elevational section on the line IIII in FIG. 1;

FIG. 3 shows the same pump in section on the line IIIIII in FIG. 1;

FIG. 4 is a sectional plan view of the pump taken on the line IV-IV in FIG. 3; and

FIG. 5 shows a detail of the pump in section on the line VV in FIG. 2.

Referring now to the drawing in detail, and initially to FIG. 1, there is seen a gear pump whose drive shaft 1 is journaled in the pump casing and carries an internally toothed cup-shaped rotor 2. The teeth of the rotor 2 mesh with the external teeth of a rotor 3 of smaller pitch diameter which is mounted on a shaft 4 journaled in a pump cover 5, and whose axis is offset from that of the shaft 1 as is best seen in FIG. 3. A sickle-shaped stationary member 6 fills the gap between those teeth of the rotors 2, 3 which are not in meshing engagement. The member 6 is secured to the cover 5 by two pins 7, 8. The circular pump cover 5 is attached to the casing 10 by a locating pin 11 and by four machine screws 9 whose heads abut against the cover (see FIG. 4), and whose shanks pass through corresponding smooth bores of the cover with sufficient clearance to permit some pivotal movement of the cover about the pin 11 when the screws 9 are loosened, thereby ensuring alignment of the member 6 with the teeth of the rotor 2.

If so desired, the pins 6, 7 may be replaced by a single pin fastened to the cover 5 and engaging a slot in the center of the member 6 in a manner not further illustrated. Such an arrangement provides alignment between the member 6 and the teeth of both rotors 2 and 3 during pivotal adjustment of the position of the pump cover 5.

Reverting to FIG. 1, there is seen a screw cap 13 which is attached to the casing 10 by an internally flanged, threaded ring 15 and encloses a filter compartment 14 in which an oil filter 12, indicated by broken lines, may be mounted on the cap 13. The filter, which is ring-shaped, envelops the pump cover 5. The cover engages an annular rib of the casing 10 and radially overhangs the rib so that an annular groove is formed in which the threaded ring 15 is sealingly fastened under the pressure of the screws 9 by means of integral projections 16 on the flange of the ring. As best seen in FIG. 4, an integral lug 17 on the flange of the ring 15 extends from the filter compartment 14 into an axial suction duct 18 in the casing 10, and thereby secures the ring 15 against rotation. The cap 13 is preferably made of transparent material to permit observation of the oil before it enters the pressure space of the pump.

A sheet metal partition 19 attached to the cover 5 separates an elongated upright channel 20 from the filter compartment 14. The orifice at the open top end 21 of the channel 20 communicates with the topmost portion of the filter compartment through the filter 12 when the same is installed. The bottom of the channel is longitudinally closed. As is apparent from FIG. 2, the aforementioned suction duct 18 communicates with two internally threaded intake openings 22, 23 is the casing 10 either of which may be connected to an oil storage tank for convenience of installation whereas the other one is normally plugged as shown at 23.

Oil admitted to the filter compartment through one of the intake openings 22, 23 and the suction duct 18 passes through the channel 20 and an aperture 24 in the cover 5 (FIG. 1), which transversely communicates with the channel 20 at the closed end thereof, into the pump chamber in which the rotors 2, 3 operate, and is discharged through a discharge duct 25 which tangentially enters anannular space 26 about a valve 27 which will presently be described in more detail. The oil is discharged under pressure from the casing 10 through a discharge orifice 28 (FIG. 2) to the oil burner nozzle.

The discharge duct 25 also communicates through a connecting bore 29 with a chamber 30 in the casing 10 through which the shaft 1 passes. The chamber 30 is sealingly separated from the remainder of the cavity in the casing 10 by the radial imperforate rear wall of the rotor 2, whereby the rotor is urged axially toward the pump cover 5 by the pressure of the pumped fluid for sealing engagement with the cover and with the rotor 3. The chamber 30 also communicates through a bore 37 with a normally plugged auxiliary outlet 38 in the casing 3 from which pressure fluid for operating hydraulic furnace controls may be drawn if so desired.

When the pressure of the pumped oil exceeds a predetermined pressure, oil is returned by the afore-mentioned valve 27 to the non-illustrated storage tank through a pressure-relief bore 31 and a return line connector 32 shown in FIG. 2 when the tank is located to permit return flow of the oil by gravity. If the pump is connected to a tank located at a higher level, the connector 32 is preferably plugged. A branch duct 33 communicates with the bore 31 and extends from its junction with the bore 31 in two opposite directions as best seen in FIG. 4. One terminal portion 36 of the duct 33 is longitudinally closed, the other terminal portion has a flaring orifice communicating with the filter compartment 14, and is normally closed by a conforming plug 34 of oil resistant, resilient plastic. The plug 34 is prevented from movement inward of the duct 33 by the conforming engagement of its flaring head with the orifice of the duct, and is retained in the duct by the flange of the threaded ring 15. As best seen in FIG. 3, a notch 35 in the flange is large enough to permit flow of oil between the duct 33 and the filter compartment 14 in the absence of the plug 34, but its edges extend over the plug to secure it in its position. If gravity return of excess oil is not available, the screw 'cap 13 is removed from the pump, and the plug 34 is driven forcibly into the blind terminal duct portion 36, thereby connecting the bore 31 with the filter compartment 14 for return of excess oil under pressure to the suction side of the pump.

The valve arrangement which maintains a desired maximum pressure in the fuel delivered to the burner, and connects the fuel supply to the burner only when the pump reaches a predetermined speed, and which disconnects the burner from the fuel supply when the pump speed drops below the predetermined value is best seen in FIG. 2.

A horizontal bore 39 in the pump casing 10 has an axially central portion in which a main piston 40 is slidably received. The piston 40 of circular cross section encloses a generally cylindrical coaxial space in which an auxiliary piston 41 is axially movable. A helical compression spring 42 biases the piston 40 toward the left, as viewed in FIG. 2, and this direction will hereinafter be referred to as forward.

The axially terminal enlarged portions 43, 44 of the bore 39 are partially threaded. A plug 46 is threadedly received in the forward terminal portion 44 and has an axial passage 45 with an enlarged inner or rear orifice 47 in which an annular gasket 48 is arranged. The threaded discharge orifice 28 in the plug 46 is normally connected to the oil burner.

The rear terminal portion 43 of the bore 39 threadedly receives a pipe nipple 49 whose bore is movably sealed by the head 50 of a screw 51. The screw is secured against outward displacement from the nipple 49 by an integral shoulder of the latter and carries an internally threaded ring 52. The aforementioned spring 42 is interposed between the ring 52 and the main piston 40 so that the tension of the spring can be adjusted by threaded movement of the ring 52 on the screw 51.

A radial lug 53 on the ring 52 slidably engages an axial slot 54 in a sleeve 55 which is fixedly fastened by a press fit in the bore of the nipple 49. The outwardly accessible end face of the screw head 50 has a hexagonal recess 56 for insertion of a conforming key by means of which the tension of the spring 42 may be adjusted. The screw 51, the main piston 40, and structure associated with the latter axially bound a rear valve compartment 57 in the bore 39. A corresponding front valve compartment at the piston 40 near the plug 46 has an annular portion about the conical front end of the piston 40, and is enlarged when the piston moves rearward from the illustrated position in which the front face of the piston 40 sealingly engages a gasket 47.

A rearwardly open axial bore 58 in the auxiliary piston 41 communicates directly with a relatively wide first (or rear) radial bore 59 in the piston 41, the two outer ends of the bore 59 being located in an annular groove 60 in the outer face of the piston 41. The axial bore 58 also communicates with a second (or forward) radial bore 62 in the piston 41 through a metering orifice 61 of reduced flow section. The outer ends of the bore 62 are located in a second annular groove 63 in the generally cylindrical outer face of the piston 41. p I,

A helical compression spring 64, much weaker than the spring 42, urges the auxiliary piston forward toward an abutment 76 on the main piston 40. The tension of the spring 64 may be adjusted by means of a screw 65 which is threadedly mounted in a coaxial flanged nipple 67 attached to the piston 40 by a short sleeve 66 of spring metal. The screw 65 and the nipple 67 close the rear end of the piston 40.

Two radial bores 68 in the main piston 40 communicate with the groove 60 in all operative positions of the pistons 40, 41-. The outer orifices of the bores 68 are located in an annular groove 69 of the main piston which is sealed by the wall of the bore 39 in the position of the valve illustrated in FIG. 2. An annular sealing edge 70 at the rear end of the bore 58 cooperates with a corresponding edge on the nipple 67 to seal radial bores 71 in the main piston 40' when the auxiliary piston 41 moves rearward from the illustrated position relative to the main piston 40.

As is better seen in FIG. 5, two narrow axially elongated slots 72, 73 in diametrically opposite portions of the outer face of the main piston 40 provides a throttling passage. Two bores 74, 74 in the main piston 40 connect the space 26 with the interior of the main piston 40 ahead of the auxiliary piston 41. Two bores 75, 75' in the main piston 40 connect the annular groove 63 in the auxiliary piston 41 to the front compartment ahead of the main piston 40. As seen in FIG. 5, the bores 74, 74' are offset from the bores 75, 75.

The valve arrangement operates as follows:

When the pump is started, oil is delivered through the discharge duct 25 into the annular space 26. The oil passes through the slots 72, 73 and the bores 75, 75' into the bores of the auxiliary piston, and is discharged from the radial bores 71 of the main piston 40 into the rear compartment 57 and to the pressure relief duct 31. The configuration of the piston 40 is such that the flowing oil does not exert significant axial pressure on the main piston 40 at this stage.

The metering orifice 61, however, produces a throttling effect which results in a pressure differential between the oil in front of the piston 41 and the oil in the rear of the auxiliary piston. When the oil flow reaches a certain rate during acceleration of the pump, the pressure differential becomes sufficient to overcome the restraint of the spring 64, and the auxiliary piston is moved rearwardly away from the abutment 76. Engagement of the edge 70 with the nipple 67 seals the bores 71, and the pressures behind the metering orifice 61 and in the front valve compartment is rapidly increased.

The main piston 40 is thereby moved rearward, and a conduit connecting the front valve compartment and the discharge orifice 28 through the passage 45 is opened.

The annular groove 69 in the main piston 40 simul-- taneously rides over the shoulder that separates the narrower central portion of the bore 39 from the enlarged terminal portion 43, and any pumped oil in excess over the requirements of the connected burner is returned to the oil tank or to the intake of the pump through the bores 75, 75 in the main piston 40, the axial bore 58 and the radial bore 59 of the auxiliary piston 41, the groove 60, the bore 40, the groove 69, and the rear compartment 57.

When the pump drive is deenerg'i zed, and the oil flow drops below a rate that can be precisely preset, the pistons 40, 41 are moved forward by the associated biasing springs, whereby the groove 69 is blocked and the bores 71 are opened. The flow of oil is interrupted instantaneously, and the oil pressure in the orifice 28 drops abruptly to practically zero.

The full amount of the oil delivered by the pump is thus utilized for establishing a pressure differential across a throttling passage, and the auxiliary piston 41 responds to the differential. The setting of the tension in the spring 64 is entirely independent of the spring setting for the main piston 40 by the screw 51. The screw 51 may be turned, and the tension of the spring 42 may thereby be altered without affecting the force'of the spring 64. The auxiliary piston starts its movement shortly before the pump reaches its design speed corresponding to full capacity discharge of oil. The valve thus opens shortly before the pump output reaches its desired rate, and it closes as soon as this rate is no longer fully maintained.

The metering orifice 61 in the auxiliary piston 41 assists the closing movement of the piston 41, and helps to hold the piston 41 in the closed position. In the absence of such a throttling device, a condition of equilibrium between the spring pressure and the fluid pressure acting on the piston 41 may be established in which the piston may no longer move into the closing position under precisely predictable conditions, and may be lifted from its seat from time to time. The pressure drop caused in the metering orifice 61 provides an additional force acting on the piston 41 in the direction of closing movement.

The suction conduits of the oil burner pump of the invention are reliably sealed against the entry of air, and the pump thus has a high suction effect. The formation of air pockets in the filter compartment and other portions of the suction area is prevented by the provision of the partition 19 whose orifice 21 is located near the highest point of the filter compartment 14. The compartment is tightly sealed by the threaded cap 13 which is not subject to leakage due to deformation which could occur under the pressure of fastening screws.

Axial clearance between the rotors of the pump and the cooperating stationary pump elements is held to a minimum by the provision of the chamber 30 filed with oil under pressure which urges the rotors against the pump cover. Radial clearance between the rotors and the stationary member 6 can be held extremely small because of the pivotal mounting of the cover 5 on the locating pin 11.

As soon as the flow of oil to the burner nozzle subsides, the conduit leading from the pump to the nozzle is closed rapidly, and the danger of flashback, always present at this stage of burner operation, is virtually eliminated.

It should be understood, of course, that the foregoing disclosure relates to only a preferred embodiment of the invention, and that it is intended to cover all changes and modifications of the examples of the invention herein chosen for the purpose of the disclosure which do not constitute departures from the spirit and scope of the invention set forth in the appended claims.

What is claimed is: a

1. A pump arrangement for an oil burner comprising, in combination:

(a) a pump casing defining a cavity therein;

(b) a cover member secured to said casing and substantially closing said cavity;

(c) a suction conduit and a discharge conduit communicating with said cavity;

(d) rotor means movable in said cavity for drawing a fluid into said cavity through said suction conduit and for discharging said fluid under pressure through said discharge conduit;

(e) a cap member enclosing an upwardly extending filter compartment about said cover, said suction conduit having an orifice in the topmost portion of said compartment;

(f) intake means for admitting fluid to said filter compartment; and

(g) a threaded ring, a portion of said ring being interposed between said casing and said cover member for sealingly securing said ring to said cover member and to said casing, said cap member threadedly engaging said ring.

2. An arrangement as set forth in claim 1, further comprising connector means on said casing and communicating with said discharge conduit for supplying operating fluid under pressure to hydraulic control means of an associated oil burner.

3. An arrangement as set forth in claim 1, wherein said intake means include a duct formed in said casing, said ring being threaded about an axis and said duct being spaced from said axis, a portion of said ring extending into said duct for securing said ring against rotation about said axis.

4. A pump arrangement for an oil burner comprising, in combination:

(a) a pump casing defining a cavity therein;

(b) a cover member secured to said casing and substantially closing said cavity;

(0) a suction conduit and a discharge conduit communicating with said cavity;

(d) rotor means movable in said cavity for drawing a fluid into said cavity through said suction conduit and for discharging said fluid under pressure through said discharge conduit;

(e) a cap member enclosing an upwardly extending filter compartment about said cover member, said suction conduit having an orifice in the topmost portion of said compartment;

(f) intake means for admitting fluid partrnent; and

(g) a partition member on said cover member, said partition member separating a vertically elongated channel from said filter compartment, said channel constituting a portion of said suction conduit and having an open upper end constituting said orifice of said suction conduit, and a longitudinally closed lower end, said cover member being formed with an aperture communicating with said cavity and with said lower end.

5. A pump arrangement for an oil burner comprising,

in combination:

(a) a pump casing defining a cavity therein;

(b) a cover member secured to said casing and substantially closing said cavity;

to said filter com- (c) a suction conduit and a discharge conduit communicating with said cavity;

(d) rotor means movable in said cavity for drawing a fluid into said cavity through said suction conduit and for discharging said fluid under pressure through said discharge conduit;

(e) a cap member enclosing an upwardly extending filter compartment about said cover member, said suction conduit having .an orifice in the topmost portion of said compartment; and

(f) intake means for admitting fluid to said filter compartment,

(1) said rotor means including two meshingly engaged gear members rotatable about respective axes extending in a common direction, one of said gear members being axially abuttable against said cover member and sealingly separating a chamber remote from said cover member in an axial direction from the remainder of said cavity, said chamber communicating with said discharge conduit,

(2) whereby said one gear member is urged into axial abutment against said cover member by fluid under pressure entering said chamber from said discharge conduit.

6. A pump afnangement for an oil burner comprising,

in combination:

(a) a pump casing defining a cavity therein;

(b) a cover member secured to said casing and substantially closing said cavity;

() a suction conduit and a discharge conduit communicating with said cavity;

(d) rotor means movable in said cavity for drawing a fluid into said cavity through said suction conduit and for discharging said fluid under pressure through said discharge conduit, said rotor means including (1) an internally geared rotor member,

(2) an externally geared rotor member having a smaller pitch diameter than said internally geared member and meshingly engaging the same for joint rotation about respective, substantially parallel, spaced axes of rotation, whereby said rotor members define therebetween a substantially sickle-shaped space, and

(3) a fill-er member interposed between said rotor members in said space, said casing and said cover member constituting wall elements of said cavity, said filler member being mounted on one of said wall elements;

(e) pivot means securing said one wall element to the other wall element for pivoting movement about a pivoting axis spaced from said axes of rotation;

(f) fastening means for fixedly connecting said wall elements in a selected pivotal position;

(g) a cap member enclosing an upwardly extending filter compartment about said cover member, said suction conduit having an orifice in the topmost portion of said compartment; and

(h) intake means for admitting fluid to said filter com .partment.

7. An arrangement as set forth in claim 6, further comprising a pin on said one wall element, said filler member being formed with a slot therein, said pin extending in the direction of said pivoting axis and engaging said slot.

8. An arrangement as set forth in claim 1, further comprising pressure relief valve means communicating with said discharge conduit, a duct connecting said pressure relief valve means to said filter compartment, and a plug of resilient material in said duct.

9. An arrangement as set forth in claim 8, said duct having a flaring orifice communicating with said filter compartment, said plug having a head conformingly received in said orifice, and said ring engaging a portion of said head for preventing movement of said plug outward of said orifice into said filter compartment.

10. A pump arrangement for an oil burner comprising, in combination:

(a) a pump casing defining a cavity therein;

(b) a suction conduit communicating with said cavity;

(0) a discharge conduit;

(d) valve means interposed between said cavity and said discharge conduit;

(e) rotor means movable in said cavity for drawing a fluid into said cavity through said suction conduit and for discharging said fluid under pressure through said valve means; and

(f) a pressure relief conduit, said valve means includ- (1) means defining .a bore, said bore having an axis,

(2) a main piston in said bore, said main piston being formed with an axially extending internal space and separating a forward compartment in said bore from a rear compartment in the bore, said discharge conduit having an orifice in said forward compartment, and said main piston being axially slidable in said bore toward and away from a forward position in which said piston blocks said orifice, a rear portion of said space normally communicating with said pressure relief conduit,

(3) first yieldably resilient means biasing said piston toward said position thereof,

(4) an auxiliary piston axially slidable in said space toward and away from a rear position in which said auxiliary piston blocks communication between said rear portion of said space and said pressure relief conduit,

(5) second yieldably resilient means biasing said auxiliary piston away from said rear position thereof, said main piston being formed with a bore connecting said cavity with a portion of said space forward of said auxiliary piston,

(6) said pistons jointly defining a throttling conduit permanently connecting said forward and rear portions of said space, and

(7) said auxiliary piston having-a face transverse of said axis in said forward portion of said space.

11. A pump arrangement as set forth in claim 10, further comprising a cap member enclosing an upwardly extending filter compartment, said suction conduit having an orifice in the topmost portion of said compartment; and intake means for admitting fluid to said filter compartment.

12. A pump arrangement as set forth in claim 11, further comprising a cover member secured to said casing and substantially closing said cavity, said filter compart ment extending about said cover member.

References Cited by the Examiner UNITED STATES PATENTS 1,497,050 6/1924 Wardwell 103-126 1,776,921 9/1930 Moessinger 230152 2,544,990 3/1951 Harrington et a1. 103220 2,684,637 7/1954- Erikson 103-426 2,751,847 6/1956 Erikson 103-220 2,775,206 12/1956 Connelly 1 03126 2,813,488 11/1957 Deska 103-126 2,880,674 4/1959 Klessig 103220 2,918,013 12/1959 Eames 103--126 2,931,314 4/1960 Erikson et a1. 103-126 DONLEY J. STOCKING, Primary Examiner.

WILBUR I. GOODLIN, Examiner.

Claims (1)

1. A PUMP ARRANGEMENT FOR AN OIL BURNER COMPRISING, IN COMBINATION: (A) A PUMP CASING DEFINING A CAVITY THEREIN; (B) A COVER MEMBER SECURED TO SAID CASING AND SUBSTANTIALLY CLOSING SAID CAVITY; (C) A SUCTION CONDUIT AND A DISCHARGE CONDUIT COMMUNICATING WITH SAID CAVITY; (D) ROTOR MEANS MOVABLE IN SAID CAVITY FOR DRAWING A FLUID INTO SAID CAVITY THROUGH SAID SUCTION CONDUIT AND FOR DISCHARGING SAID FLUID UNDER PRESSURE THROUGH SAID DISCHARGE CONDUIT; (E) A CAP MEMBER ENCLOSING AN UPWARDLY EXTENDING FILTER COMPARTMENT ABOUT SAID COVER, SAID SUCTION CONDUIT HAVING AN ORIFICE IN THE TOPMOST PORTION OF SAID COMPARTMENT; (F) INTAKE MEANS FOR ADMITTING FLUID TO SAID FILTER COMPARTMENT; AND

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