US2552633A - Liquid fuel supply device - Google Patents

Description

May 15, 1951 R. w. JOHNSON 2,552,633

LIQUID FUEL SUPPLY DEVICE Filed Deo. 26, 1947 H lll INVENTOR. E05/ PV. JOH/VSN WMWJM iiatenfed May 15, i951 UNITED STATES PATENT OFFIC 2,552,633 LIQUID FUEL sUPrLY DEVICE Roy W. Johnson, Milwaukee, Wis.

Application December 26, 1947, Serial No. 793,975

Claims. (Cl. 10S-25) This invention relates to improvements in def vices forsupplyinng liquid fuel to burners from a source of supply remote from such burner.

I n my Patent No. 2,445,069 I have shown a pumping mechanism which is adapted to deliver liquid fuel to a control device under a substantially constant hydrostatic head. The pumping mechanism utilizes a bypass associated with the pump and separate means to disconnect the pump motor if the liquid level increases over a predetermined maximum. The presence of the by-pass brings in leakage problems and increases the chances of clogging, while the extra control means complicates the device.

It is one object of the `present invention to provide a device for supplying liquid fuel to a burner which does not require the incorporation of lay-passes and separate cutoff devices for the pump m-otor.

Another object of the invention is to provide a `device of this type which is of simple construction, less liable to clog in operation, and which .is relatively inexpensive to manufacture.

These objects are obtained by providing a oo ntinuously energized motor for operating -a pump to maintain a given minimum pressure on the 'val-ve which regulates the admission of liquid to the control chamber; the operation of the .motor driven pump and its delivery of liquid Vbeing controlled by an increase in the discharge pressure above a given value. Thus the delivery -of liquid fuel -is accomplished without resort to by-passes or separate means for disconnecting the motor from its source of power. This device can Abe manufactured, therefore, at a lower cost than the mechanism shown in my prior Patent No. 2,445,069.

Objects and advantages other than those above :set forth will he apparent from the following description when read in connection with the accompanying drawing in which:

Fig. 1 `is a view partially in section and partially in elevation of one embodiment of .the present invention.

Fig. 2 is a view partially in section and partially in elevation of a second embodiment of the present invention; and

Fig. 3 is a top plan View of one element of the structure shown in Fig. 2.

The present combina-tion generally includes a continuously `energized .electric motor driving a pump of the positive displacement type ,drawing a liquid fuel from a tank or source. The pump discharges into a conduit leading toa .casing into which `liquid ilow is controlled by a valve lbiased to its open position and urged to its seated position :by a float shifting as ythe liquid level within the casing varies. A metering valve associated with the casing, controls ow'of fuel to a space heater and is adjustable to different positions as the rate of combustion of the burner is to be changed. Adjustment of the metering valve may be manual or may be by automatic means thermostatically controlled from a location remote from the burner.

Referring particularly to the drawings, numeral 5 designates a conduit from a liquid fuel source or tank (not shown) at a location below and remote from the space to be heated, Such conduit is connected with a casing 6 forming a portion of a positive displacement or constant volume pump, the impeller l of such pump being indicated as of the sliding vane type although it will be understood that other types of .positive displacement rotary impellers may be used such as shiftable vanes. A shaft 9 extends from the pump impeller 1 through a suitable packing'A i0 in the pump casing.

The pump c asing 6 has mounted thereon 4a housing I3 for enclosing power means driving the pump, which means are herein shown as an electric motor I4 of the shaded pole induction type. The shaft I5 of the motor, is connected directly with the .pump shaft 9 through a flexible coupling ,I6 herein shown as a helical spring which permits relative movement between th'e pumpV rotor and the motor rotor.

A discharge passage 20 in the pump casing 6 is connected with the inlet end of a passage 2 yI'ofa well know-n type of liquid level control device. Itis ythe function of such device to `supply liquid fuel to the burner at 'a substantially `constant hydraulic head regardless of the pressure inthe passages 20 and 2l. The liquid `leveldevice or ow contr-ol means includes a casing 24 in which is mounted an inlet valve indicated at 25 resiliently urged in the opening direction iby a spring 26. A float 21 is pivotally mounted on a bracket 28 in casing 2li and `acts on the inlet valve 2-5 .to -urge such valve in closing direction as the liquid fuel within the casing rises -tothe desired level indicated uin the drawing.

Fuel is allowed to flow by gravity from the control device to a burner (not shown) under -t'he control of an adjustable outlet valve 33 connected with a .conduit 34. The outlet valve 33 is urged in .the opening direction by a spring 3E and the degree 'of opening of .the val-ve is controlled `by a l ably mounted in the top 4l of the casing 24 and has an -adjustable cam member 42 mounted on the end thereof within the casing. The cam is engageable with an ear 46 extending from a lever 4l pivoted in the casing and bearing a leaf spring 48 extending over the outlet valve for movement into and out of contact with the end of the valve upon adjustment of such valve to Various positions as the knob is rotated to vary the portion of the cam in contact with the lever ear 46.

The electric motor I4 isV continuously connected to the source of electric power 18 and causes the pump to supply fuel under pressure to the inlet passage 2U. However, if the liquid level device is satisfied, the inlet valve 25 is closed. This causes the pressure at the delivery side of the pump to increase. At a predetermined in crease the motor I4 will stall. However, the shaded pole induction motor, when stalled, draws only a little more current than when running and hence will not overheat. The motor and pump remain stalled until the liquid level device` calls for more liquid. Y

vThe modication of the present invention,

shown in Figs. 2 and 3, differs from the structure above described by having the pump casing 5 provided with a wall 55 which, together with a Wall 56 mounted on such casing, encloses a space divided into two chambers 5l and 58 by a resilient 'diaphragm 59. The pump discharge passage 2B is now connected by a conduit 5d with chamber 5l and such chamber is connected with the inlet passage 2l of the valved control means. The wall 55 has mounted therein a guide 65 for push rod 66 which extends from the chamber into the space enclosed by the motor housing I3. A plate 6l, engageable with one end of the guide, forms one bearing surface for a helical spring 68 bearing at its other end on a plate 69 fixed on the diaphragm 59, the plate 69 providing a surface on which one end of the rod E6 may also bear. It is possible to adjust the spring 68 by screwing. the guide 65 inwardly to move the plate 6l ,and compress the spring. The other end of the rod 66 is formed to provide a universal joint i3 supporting brake shoe lll with brake lining i5 to bear against the edge of a disk i6 fixed onmotor shaft I6.

' As previously explained, the motor i4 is con-'- tinuously energized and the pump 5, 1, being of the positive displacement type, discharges fuel under pressure whenever the shaft I5 rotates. So long as the flow control means requires liquid fuel for the burner, substantially all the output of the pump will be required and the pressure in the conduit 20 and inlet passage 2l remains substantially constant. However, if less fuel is required by the burner, the level of fuel in the control casing 24 rises and float 21 closes the inlet valve 25. Continued operation of the motor l5 and pump 6, 'l then builds up pressure in the pump discharge passage 20.

This pressure builds up on diaphragm 59 and compresses spring 68 until pressure plate 69 presses on the end of rod 66. Brake shoe 'I4-i5 is then pressed against the edge of disk -l slowing down the motor and the pump, until the required amount of fuel is delivered or until the motor i4 stalls. l

It will be seen that the present device .provides a power-driven pump continuously maintaining a predetermined minimum pressure on the inlet 'valve of flow control means which in turn maintains a given hydraulic head on the llow control means outlet valve, except for small and relative infrequent variations in head as the quantity of fuel iowing to the burner is varied. Power is continuously applied to the pump so that the pump is ready for operation at all times and the pump-motor merely stalls when the pump discharge pressure exceeds a predetermined value. When the motor has stalled, continued energization of the motor holds the pump in substantially a given position and causes the pump to act as a check or non-return valve. The flexible coupling between the motor and pump shafts reduces the effect of stalling on the motor and may act as source of power to keeprpressure on the fuel until a minimum value is again .-.reached whereupon the pump restarts. This simple construction eliminates by-passes subject to clogging and additional power cut-ofi means, thus' making the unit more effective and practical and lessening its cost of manufacture.

Although but two embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

v I claim: ,Y l. in a device for supplying liquid fuel to a burner, a chamber, a valve controlling flow Vof fuel into'the chamber under control of change of liquid level therein, a continuously energizedv shaded pole induction type electric motor, a constant volume pump driven by said motor for maintaining a supply of fuel to said valve, a brake for retarding the operation of said pump, and means responsive to pump discharge pressure above a given value for actuating the brake.

2. A device for supplying liquid fuel to a burner as claimed in claimV 1, in which said means consist of a diaphragm one side of which is connected to the discharge side of said pump and the movable portion of Which' is connected to said brake. l

3. In a device for supplying liquid fuel to a burner, a chamber, a valve controllingflow'of fuel into the chamber under control of change of liquid level therein, a continuously energized motor, a pump driven by said motor for maintaining a supply of fuel to Vsaid valve, a brake for retarding the operation of said pump, and means responsive to pump discharge pressure above a given value for actuating the brake. Y

4. In a device for controlling liquid fuel flow to a burner, the combination with a casing having an inlet and an outlet, a valve in said inlet, a float operatively connected to said valve to openrand close the valve to maintain a prede-jY termined fuel level in the casing, of a pump connected to a source of fuel and to said inlet for delivering fuel under pressure to said inlet, a continuously energized motor, andra flexible coupling connecting said motor and said pump for storing energy upon relative rotation therebetween, the pressure rise incident to closure` of said valve and continued operation of said motor being operable to stall said motor, said coupling being operable to store energy and maintainV the pressure when said motor stalls. Y

5. In a Vdevice for controlling liquid fuel ow tc a burner, the combination with a casing having an inlet and an outlet, a valve insaid inlet, a iloat operatively connected to said valve to open and' close the valve to maintain a predetermined fuel level in the casing, of a constant volume REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number 10 Number Name Date Fritz Nov. 27, 1917 Wilson June 9, 1931 Teesdale June 20, 1935 Harrington May 1.8, 1943 Johnson July 13, 1948 FOREIGN PATENTS Country Date Germany 1932

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