US2145404A - Fuel supply unit for oil burners - Google Patents

Description

Jan. 31, 1939. H, c;` OSBORNE 2,145,404

FUEL SUPPLY UNIT FOR OIL BURNERS Filed Aug. 13, 1937 2 Sheets-Sheet l klm 3l, 1939 H. C. OSBORNE 145,494

FUEL SUPPLY UNIT FOR OIL BURNERS Filed Aug. 13, 1957 2 Sheets-Sheet 2 QQ/Um 2m? j?) .Zferef C s 762%@ Patented Jan. 31, 1939 FUEL SUPPLY 'UNIT FOR OIL BURNEBS Herbert C. Osborne, Racine, Wis., assignor to Webster Electric Company, Racine, Wis., a corporation oi' Wisconsin Application August 13, 1937, Serial No. 158,853

Z Claims.

fuel supply.

In particular, the

fuel supply unit details of the regulator valve, strainer, and the major part of the pump may correspond to those disclosed in my prior application, Serial No. 118,794, led

January 2, 1937, on

Fuel supply units for oil burners, the disclosure of which application is hereby incorporated by lreference thereto.

Fuel units of the present type are adapted to be used in thegun type of burner which is provided with a motor,

a fan blower, ignition devices, a nozzle, and one of the present fuel units, all of which is controlled by suitable electrical controls. down by shutting off In such case the oil burner is shut the motor, which stops not only the fan but the gear pump, and upon reduction of the liquid fuel pressure, due to the stoppage of the gear pump, the regulator valve closes the burner port and shuts off the oil to the nozzle.

One of the disadvantages of such prior art devices is that when the burner is shut off, pressure in the regulator valve decreases more slowly, and not in proportion to the decrease of air being supplied to the combustion chamber. 'I'he keted and which have narrow air passages.

the oil is permitted If to spray into the furnace while the motor is reducing its speed, which may occur with the ordinary type of valve, in spite of a leakage slot across the piston, the reduced fan speed does not give suiiicient air to burn this oil completely.

I'he result is not only a smoky flame, but this violent pu'ing action at the end of the ring period.

One of the objects `of the present invention is the provision of an improved fuel supply unit which is adapted to eliminate completely such locomotive action or furnace flutter.

Another object of the invention is the provision of an improved fuel unit of the class described, in which the pressure at the fuel pump outlet is very quickly reduced to a negligible amount as soon as the controls operate to shut down the burner, thereby positively preventing continuance of the spray of liquid fuel while the motor is reducing its speed.

Another object is the provision of an improved attachment for fuel supply units of the type disclosed in my prior application, which is adapted to eliminate locomotive action or furnace flutter in furnaces having very narrow air passages, when used with such a unit.

Another object is the provision of a fuel supply unit attachment having a solenoid-operated valve of an improved structure, by means of which valve chatter, valve seat destruction, valve leakage, and -cyc1e hum at the valve are eliminated.

Other objects and advantages of the invention will be apparent from the following description and the accompanying drawings, in which similar characters of reference indicate similar parts throughout the several views.

Referring to the drawings, of which there are two sheets,

Fig. 1 is a vertical sectional view, taken on the plane ofthe axis of the pump shaft, showing the details of structure of an arrangement constructed according to the present invention;

Fig. 2 is a vertical sectional view, taken on a plane at right angles to the axis of the pump shaft and in the axes of the strainer and regulator valve;

Fig. 3 is a wiring diagram;

Fig. 4 is a wiring diagram of a modified form of delayed control.

Referring to'Fig. 2, the fuel unit is indicated in its entirety by the numeral I0, and it comprises a housing, usually of cast metal, which is provided with a strainer housing Il, a regulator valve housing I2, joined together by a pump housing portion I3.

'Ihe details of construction of these parts of the unit are fully disclosed in my prior application, and therefore will only be described briey 5o here. The strainer housing is provided with a partition Il, which supports a strainer unit I 5, for the purpose of removing solid matter from the fuel as it passes through the strainer housing I I. Thus the port I6 may be used as the strainer u inlet, the liquid fuel passing through the separate strainers, and through ports in the partition I4, into the space I1 above the partition. 'I'he horizontally extending pipes 36 and 39 are used for gauges. The space |1 above the partition communicates with the intake of the pump shown in Fis. 1.

The pump of Fig. 1 is driven by a shaft I3, which is rotatably mounted in the pump housing I3 and provided with two sets of gears, the low pressure gears I9, and the high pressure gears 20. The low pressure gears i9 are preferably thicker than the high pressure gears 29, and therefore adapted to pump up from the source of supply an excess of liquid fuel over that required to supply the high pressure gears. The excess fuel is delivered into a reservoir 2|, which preferably surrounds the pumping gears and tends to deaden the sound, and thus the high pressure gears are provided with a constant supply of liquid from the reservoir 2 I.

The course of the fuel through the pump is as follows: The space I1 of the strainer housing communicates with the intake of the low pressure pump gears |9. The output from the low pressure gears I9 is into the reservoir 2|, which is in communication with a by-pass conduit 22, through a conduit 23, located at the top of the pump unit so that the reservoir 2| is always full of fuel up to a point above the gears, thereby assuring self-priming of the pump.

The high pressure gears 26 have their intake connected to the reservoir 2|, and have their output connected to the pressure chamber 24 of the regulator valve housing I2. The regulator valve housing I2 has a burner outlet port 25 and a by-pass outlet port 26. The by-pass outlet port 26 communicates with the by-pass conduit 22 and with the space 21 above the regulator valve partition 26.

The regulator valve partition 26 supports a diaphragm or pressure responsive bellows 29, to which is secured the piston 3Iil, which is slidably mounted in a sleeve 3|, forming a cylinder. The piston 30 has a port 32 adapted to serve as a valve in connection with the edge of the cylinder 3|, and the port 32 communicates through the bellows 29 and through an aperture 33 with the space 21 above the partition 26. Ihus the port 32 is a by-pass port which by-passes excess liquid fuel through the port 32, bellows 29, aperture 33, space 21, port 26, to the by-pass conduit 22.

The piston 30 supports a needle valve 34, which is adapted to cooperate with the burner port 25 to open or close the burner port. A spring 35 engages the inside of the piston and urges the piston downward, the pressure of the spring being` regulated by a threaded member 36.

The piston 30 may be provided with the leakage slot 31 which is formed between the piston 30 and cylinder 3| by a grooved or flattened portion on the piston, and which is intended to permit the by-pass of fuel from the pressure chamber 24 until the needle valve 34 is actually tightly .seated against'the burner port.

. The inta-ke |6 of the strainer is connected by a suitable pipe to the source of fuel supply, the pipe being submerged in the liquid fuel, while the by-pass port 22-may be connected by a pipe back to the source of fuel supply so that any excess fuel from the regulator valve or from the low pressure gears is by-passed back to the tank.

The pump unit is preferably built up by means of the high and low pressure gears |9 and 26 and a plurality of metal plates 4043, which are Secured in place by screw bolts and aligned by means of pins 44, as described in my prior application. e

In order to immediately relieve pressure at the high pressure gears of the pump when the burner is to be shut down, the fuel unit described in my prior application may be provided with an improved attachment. A new cover plate for the reservoir 2| is substituted for the cover plate of my prior application, the new cover plate 45 being larger, in order to provide space for a valve 46, and being provided with a platform top 41, for the purpose of supporting a solenoid 43.

I'he cover 2| is again secured to the unit by means of screw bolts and with a suitable gasket 49 so as to provide a liquid-tight reservoir 2| about the pump unit and about the valve unit 46.

The last plate 43 of the pump unit may be provided with a discharge port 50 leading from the output of the high pressure gears 2|) toward the reservoir 2|. This outlet 50 is, however, embraced by a valve supporting plate 5|, which is provided with a chamber 52 communicating with discharge port 50. The valve supporting plate 5| is provided with the usual attaching flange 53 and is secured to the plate 43 by suitable screw bolts, at its upper side the valve supporting plate 5| being provided with a cylindrical bore 54 for receiving a valve sleeve 55, which may have a tight frictional fit in the bore 54.

The valve sleeve 55 is provided with a valve port 56, comprising a cylindrical bore centrally located in the sleeve and communicating with the chamber 52. The discharge port 50 from the high pressure gears 20`into the reservoir 2| has no access to the reservoir 2| except through the Dort 56.

The valve sleeve 55 supports a cylinder sleeve 51, comprising a tube having a cylindrical bore with a tight frictional t on the upper cylindrical portion of the valve sleeve 55.

The tube 51 may be provided with discharge ports 58 located above the valve port 56, and it slidably supports a piston 59 provided with a needle valve 60 having a conical point. The needle valve 60 is adapted to form a liquid-tight closure in connection with the circular edge at the upper end of the valve port 56 when the piston 59 is in its lower position, that shown in Fig. 1.

The piston 59 is adapted to slide freely in the cylinder 51 and is urged upward by a relatively light helical spring 6|, which is of suillcient strength to lift the valve 60, piston 59, spring 62, and solenoid core 63, when the solenoid 48 is not energized.

The diagrammatic circuit for this device is shown in Fig. 3, and it will be observed that the usual controlling devices in a control box 64 are used for controlling the burner motor 65 and the solenoid 48.

The motor 65 and solenoid 46, being connected in parallel in this figure, the solenoid is shut off as soon as the motor is cut out of circuit. Thus the valve 60 opens as soon as the solenoid 46 is de-energized, or as soon as the burner is shut off.

'I'he housing 45 is conveniently shaped at its upper end to provide space for the valve assembly 46, and at its upper end may be provided with a ilat wall 66 used for supporting the solenoid. 'I'he fiat wall 66 is provided with a recess or bore 61, the axis of which is aligned with the needle valve 6|, surrounding a smaller bore 66, which passes through the wall 66.

The bore 69 is adapted to receive the coil spring 4in a cylindrical recess 99 in the piston 59. The

upper end of the spring 62 is seated in a similar cylindrical recess 10 in the solenoid core 93. The solenoid may be supported by means of a nonmagnetic metal sleeve 1I, which has a lower radially extending attaching iiange 12 fitting inA the recess 61 above a gasket 13. The sleeve 1I is adapted to slidably receive the core 83, which may be hexagonal, if desired. or cylindrical.

'I'he attaching ange 12 is held in the recess 91 by a metal plate 14 which has a centrally located bore for passing the sleeve 1I and counter-sunk securing apertures 15 for receiving the body and head of the screw bolts 19 which clamp the plate 14 to the upper wall 99.

The upper end of the tube 1I may be secured in a threaded cap 11 which has a bore 13 that may be cylindrical for s lidably receiving the core 63. The bore 18 forms a continuation of the bore in the sleeve 1|.

A housing 19, which may be made of cast metal or sheet metal, surrounds the solenoid coil 48, and has a centrally located bore 90 for passing over the cap 11. The lower edge of the` cylindrical housing 19 is open, and the edge engages the top wall 86.

At one side the housing 19 is formed with an aperture 8i, which may be provided with a ntting 82 having a threaded bore for receiving the usual metal conduit pipe 83 for enclosing the Wires 84.

The threaded ferrule 35 has a threaded bore 88 fitting the threaded surface on the cap 11 so that the ferrule may be driven down against the housing 19 to secure it in place. The core 53 is made of magnetic metal such as steel, and the housing 19 may also be made of magnetic metal for completing the magnetic circuit outside of the coil 48. The ferrule or nut 85 is of magnetic metal.

The coil 48 may be prewound to the shape shown, and the length of the core 63 is such that Y it projectsvbeyond the upper end of the coil 48 more than it does at the lower end when it is in the dotted line position of Fig. l, or in the full line position. Thus, when the solenoid is energized, the core 63 is drawn downward and tends to assume a central position with respect to the coil 48, exerting a downward force at all times.

The spring 62 between the core armature and the needle valve 60 is relatively stiff compared to the spring 6l, which is a relatively light spring, compressed between the valve sleeve 55 and the piston 59.

Spring 6| is not of sufcient strength to resist movement of the armature 63 by the coil 48 while the spring S2 bears a relation in strength to the force exerted by the solenoid, so that after the needle valve 6i is moved into closed position, the core 63 moves farther in that direction, such as, for example, by about one-sixteenth of an inch, compressing the spring 62. 'I'he movement of the needle valve might be about one thirty-secondth of an inch.

The operation of the fuel unit is as follows: The pump operates in the usual way, described in my prior application, providing the burner with a substantially constant supply of liquid fuel under substantially constant pressure, and by-passlng the excess back to the reservoir or tank. When the burner is turned on by the controlling apparatus, that is, when the burner motor is started, solenoid 48 is also energized, forcing armature 63 downward and closing the needle valve BIJ.

The fuel unit then suppliesthe burner with the liquid fuel until the controlling apparatus shuts down the burner or deenergizes the motor.

As soon as the motor is out out of circuit, the solenoid 48 is also cut out of circuit, releasing its amature 93 to slide upward to the dotted line position of Fig. l under the action of the spring 9|. The needle valve 60 is thus promptly opened as soon as the motor is shut off, and the liquid fuel from the output of the high pressure pump gears 20 is immediately released into the reservoir 2|.

The reservoir 2i, of course, is in communication with the by-pass conduit 22, which leads back to the supply tank.

While the motor comes to a stop and the air supply is being diminished at a faster rate than the oil supplied from the high pressure gears 20, this oil supply is immediately bypassed into the reservoir, diminishing the oil supplied to the burner port to zero.

'I'hus there is no supply of liquid fuel to the burner in a manner disproportionate to the supply of air during the shutting down of the burner, and there is no puffing of the furnace or smoke, or what is termed locomotive action or furnace flutter. When the burner is turned on. the valve 6I is immediately closed, and pressure builds up in the manner described in my prior application.

Referring to Fig. 4, this is a modified form of control, in which the motor 65 and solenoid 48 are indicated by the same indicia. This embodiment has a thermostatically actuated bi-metallic switch arm 90, which is surrounded by a heating coil 9| that is in parallel with'the energizing circuit of the motor 65.

The contacts 92, 93 are adapted to be closed by the switch arm 90 when the bi-metallic switch arm 99 becomes heated. Contact 93 is connected to solenoid 48, and the other end of the solenoid is connected to the supply circuit 94. Contact 92 is connected by means of a iiexible lead or pigtail 95 to the conductor 96, which leads to the controlling device 64.

The operation of this embodiment is as fola lows: When the control 64 energizes the circuits 94, 96. the motor 65 starts, and the heater 9| is energized. 'I'he motor is thus permitted to come up to speed first, because the circuit of the solenoid 48 is opened at the contacts 92, 93. After the heater 9| has been energized for a predetermined period of time, sufficient heat has been transferred to the bi-metallic thermostat 90 to *cause it to bend and close the contacts 92, 93.

Then the solenoid 48 is energized and it acts to close the by-pass valve 60. From this point on, the pump supplies oil to the regulator valve, and

pressure builds up in the regulator valve. The` solenoid circuit is maintained in closed position as long as the motor circuit is energized.

When the circuit 94, 95 is de-energized by the control, the solenoid 48 is, of course, immediately de-energized, and the by-pass valve 60 is immediately opened, relieving the pressure at the pump and stopping the supply of liquid fuel under pressure to the regulator valve and to the burner at once. i

` The thermostat 90 then returns to the position of Fig. 4 so that it is ready for a new startin cycle.

The present device is thus adapted to stop the supply of oil under pressure to the regulator valve and to the burner as soon as the motor circuit is de-energized. There is no possibility of the continuance of oil being supplied to the burner after the supply of air has ceased.

It will thus be observed that I have invented an improved fuel unit by means of which locomotive action" or furnace flutter is eliminated.

desire to avail myself of all changes within the scope of the appended claims.

Having thus described my invention, what 1 claim as new and desire to secure by Letters Pat-l ent of the United States, is:

1. In a gear pump for oil burners, the combination of a support with bearings for a drive shaft, said support'carrying a plurality of plates, and certain of said plates having gear recesses, gears in said recesses, one of said gears being carried by said drive shaft, an electric motor for driving said shaft and a housing for enclosing all of said plates, said housing carrying a solenoid energized from the motor circuit and said housing forming a by-pass reservoir about said pump, a cover plate in said latter housing and completing said pump, said pump having an inlet communicating with said reservoir and an outlet, said cover plate being provided with a passage communicating the pump outlet with the reservoir and having a slidably mounted valve member controlling said passage and operated in the closing direction by said solenoid, said valve member being actuated to open position by spring means, said solenoid having a movable core member and spring means between said core member and said valve, the spring means between said valve member and said core member being of greater strength to actuate said valve to closed position, whereby the valve is closed when the motor circuit is closed and the solenoid is energized and the valve is opened as soon as the solenoid is de-energized to permit immediate reduction of pressure in the supply from said pump when themotor is de-energized 2. In a gear pump for oil burners, the combination of a support with bearings for a drive shaft, said support carrying a plurality of plates, certain of said plates having gear recesses, gears in said recesses, one of said gears being carried by said drive shaft, an electric motor for driving said shaft, a housing for enclosing all of said plates, said housing carrying a solenoid energized from the motor circuit, said housing forming a by-pass reservoir about said pump, and a cover plate in said latter housing completing said pump, said pump having an inlet communicating with said reservoir and an outlet, said cover plate being provided with a passage communicating the pump outlet with the reservoir and having a slidably mounted valve member controlling said passage and operated in the closing direction by said solenoid, said valve member being actuated to open position by spring means, said solenoid having a movable core member and spring means between said core member and said valve, the spring means between said valve member and said core member being of greater strength to actuate said valve to closed position, whereby the valve is closed when the motor circuit is closed and the solenoid is energized and the valve is opened as soon as the solenoid is deenergized to permitimmediate reduction of pressure in the supply from said pump when the motor is de-energized, and time delay means for controlling the energization of said solenoid whereby the motor may be rst brought up to speed before the valve means is closed, thereby facilitating the quick starting of the pump.

HERBERT C. OSBORNE.

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