US3006407A - Liquid fuel burner system - Google Patents

Description

Oct. 31, 1961 K. SHEW LIQUID FUEL BURNER SYSTEM Filed March 24, 1958 .Znvezziop '12/ew United States Patent 3,006,407 LIQUID FUEL BURNER SYSTEM Kelvin Shew, Shirley, Solihull, England, assignor to Joseph Lucas (Industries), Limited, Birmingham, England Filed Mar. 24, 1958, Ser. No. 723,299 2 Claims. (Cl. 158-363) This invention relates to a liquid fuel burner system of the kind which includes a burner of the swirl type and a spill return pipe, the object of the invention being to enable the flow in the spill pipe to be automatically regulated in a simple and reliable manner by providing and utilizing a controlling fuel flow which is a fixed fraction of the fuel discharged by the burner for burning.

A system in accordance with the invention includes a pair of proportional-flow valves as hereinafter defined and connected respectively to the burner supply and spill pipes, an intermediate passage interconnecting the valves, a throttle in the spill pipe, means adapted to bias the throttle to its closed position, a secondary spill passage communicating with the spill pipe valve, and means dependent in part on the pressure in the secondary spill passage for actuating the throttle.

In the accompanying drawings:

FIGURE 1 is a part sectional elevation illustrating diagrammatically one form of the invention.

FIGURE 2 is a fragmentary sectional view illustrating a modified feature.

In the example illustrated by FIGURE 1 of the accompanying diagrams, the proportional-flow valve a through which the fuel is supplied from a feed pump b to a burner c along a supply pipe a, includes a main passage e which contains a restricted orifice f, and a chamber which is divided into two compartments g, i by a flexible diaphragm k. The compartment g contains an outlet seating m with which co-operates a closure member n carried by the diaphragm. Further the said compartment g is connected to the main passage by a passage 0 to the upstream side of the orifice f, and in the passage 0 is contained a restricted orifice p the area of which is a predetermined fraction of the area of the orifice f. The compartment i is connected to the main passage by a passage q at the downstream side of the orifice f.

The proportional-flow valve through which fuel is spilled from the burner c to a sump or the inlet side of the pump b is similar in construction to the valve a, and corresponding components are identified by similar reference letters to each of which a suflix has been added, such as a g etc. The spillage from the burner is conveyed to the valve a by a pipe r. In this valve the compartment g communicates with the downstream side of the orifice f and the compartment i communicates with the upstream side of the said orifice.

The seating m in the valve a is connected to the compartment g of the valve a by an intermediate passage s. Further the seating m of the valve a is connected to a secondary spill pipe I. From the valve a the spilled fuel passes to a throttle u, contained in a chambered body part v which is divided into two compartments w, x by a diaphragm y. The throttle is attached to the diaphragm, and to the opposite side of the diaphragm is attached a tension spring z which biases the throttle to its closed position. Further, the secondary spill passage t communicates with the compartments w, x at opposite sides of an aperture 4 which is controlled by an adjustable plug 5.

Starting with the system in the condition represented by FIGURE 1, the mode of action is as follows:

On starting the pump, the first efifect of the pressure of the fuel is to lift both of the closure members n, n of the valves a, n off their seatings, and so enable the throttle u to be moved to its fully open position against the action of the spring z by the pressure of the fuel in the secondary passage acting on the diaphragm y. So long as it is re quired to effect a low rate of discharge of fuel from the burner this condition is maintained, and a sufiiciently large proportion of the fuel is returned by the spill pipe to ensure the desired effective nebulization of the discharged fuel. To obtain an increased discharge from the burner the plug 5 is retracted from the associated aperture 4, thus diminishing the fuel pressure difference acting on the diaphragm y, and enabling the spring z to return the throttle towards its closed position. When this pressure difference is sufliciently reduced, the throttle is moved to its fully closed position, and in this condition the Whole of the fuel supplied by the pump is discharged through the burner.

The actuation of the plug 5 may be effected by any convenient means responsive to a variable factor associated with the working of the system supplied with fuel by the burner. Such a factor may be the speed of an engine driven by the combustion products. Another factor may be a change of atmospheric pressure due to a change of altitude, or pressure of the combustion air supplied by a blower. Still another factor may be the temperature in the combustion chamber acting on a thermometric device. Moreover, the plug may be actuated by manually-operable means.

An alternative means for actuating the throttle is illustrated by FIGURE 2. In this example a constantly open aperture 4 is provided in the secondary spill passage, this aperture being of appropriate size to maintain a given fuel pressure difference at the opposite sides of the diaphragm y, and movement of the throttle is effected by varying the tension of the spring 2. In the example illustrated one end of the spring is attached to slidable actuator 6 which is movable by, for example, a pinion 7 acting on a rack 8, the pinion being movable by any of such factors as those above mentioned, and also, if desired, by manually-operable means.

The design of the system above described is such that over a normal range of Working, the ratio of the fuel flow through the orifice and the flow through the orifice p is constant. Also the ratio of the flow through the orifice f and the flow through the orifice 12 is equal to the said constant. Further the ratio of the difference of the flows in the pipes d and r, and the difference of the flows in the pipe s and orifice p is also equal to the said constant. Consequently, the flow through the secondary spill passage t is a fixed fraction of the fuel discharged by the burner c for burning. Thus, the fuel flow through the intermediate passage s to the compartment g of the valve a is a fixed proportion of the fuel flow through the supply pipe d, and as the fuel flow from the compartment g through the orifice p is a corresponding fixed proportion of the fuel flow through the spill pipe r, it follows that the fuel flow from the compartment g through the secondary spill passage t is, as indicated above, a fixed fraction of the fuel discharged by the burner for burning.

From the foregoing it will be seen that the fuel flow through the secondary spill passage t is used for regulating the flow in the spill pipe r, and is attained by the joint effect of the two proportional-flow valves a and a Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

l. A liquid fuel burner system comprising in combination a burner of the swirl type, a fuel pump, a fuel supply pipe leading from the fuel pump to the burner, a spill pipe leading from the burner, a pair of similar proportional-fiow valves connected respectively to the fuel supply and spill pipes, each valve having a closure member, a pressure-responsive member carrying the closure member, a chamber divided by the pressure-responsive member into two compartments, a main passage provided at a position intermediate its ends with a restriction and interconnecting portions of the pipe to which the corresponding valve is connected, an unrestricted passage connecting one of the two compartments to the main passage at the side of the restriction therein nearest to the burner, a restricted passage connecting the other compartment to the main passage at the other side of the restriction therein, and a seating for the closure member in the said other compartment, a passageway communicating at opposite ends respectively With the seating of the valve connected to the fuel supply pipe and with the said other compartment of the valve connected to the spill pipe, a throttle in the spill pipe at a position further from the burner than the valve connected to the spill pipe, means adapted to bias said throttle to its closed position, a secondary spill passage communicating with the seating of the last mentioned valve, means for creating a pressure difference in the secondary spill passage, and means responsive to the pressure difference in the secondary spill passage for actuating the throttle.

2. A liquid fuel burner system according to claim 1, and comprising a chambered body part divided into two compartments by a pressure-responsive member constituting the means responsive to the pressure difference in the secondary spill passage for actuating the throttle, a spring constituting the means adapted to bias the throttle to its closed position, and adjustable means for varying the pressure difference in the secondary spill passage, the two compartments of the body part being in communication with the secondary spill passage at positions for enabling the different pressures in the secondary spill passage to act on opposite sides of the throttle-actuating member.

References Cited in the file of this patent UNITED STATES PATENTS 2,265,961 Ziebolz Dec. 9, 1941 2,698,141 Dickey et a1. Dec. 28, 1954 2,738,003 Carey Mar. 13, 1956 2,806,519 Basford et a1. Sept. 17, 1957

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