US2976885A - Fuel control valves - Google Patents

Description

March 1961 G. H. GARRAWAY ET AL 76,885

FUEL CONTROL VALVES 2 Sheets-Sheet 1 Filed July 8, 1955 INVENTORS GEORGE H. GARRAwAY HT 5 A RICHARD F? KumuP, I

BY M y/w ATTORNEYS G. H. GARRAWAY ETAL 2,976,885

March 28, 1961 FUEL CONTROL VALVES 2 Sheets-Sheet 2 Filed July 8, 1955 S m H m: w W? n Q g BY M7/% #0 FUEL CONTROL VALVES George H. Garraway, Darien, Conn, and Richard P.

Kirkup, Packanack Lake, N.J., assignors to Orr & Sembower, Inc., Reading, Pa., a corporation of Pennsylvania Filed July 8, 1955, Ser. No. 520,694

2 Claims. (Cl. 137-608) This invention relates to flow control valves for fiuid circulation systems and the like, and more particularly to improvements in pressure sensitive flow control valves for use in fuel supply systems.

This application is a continuation-in-part of the copending application of George H. Garraway and Richard P. Kirkup Serial No. 213,068, filed February 28, 1951, which issued on July 10, 1956, as Patent No. 2,753,927.

In the past it has been customary to supply liquid fuel, such as oil, to an atomizing fuel injector assembly from a fuel pump either directly or through an oil pre-heater, the flow of fuel to the injector assembly being controlled by a pressure regulating valve. Such pressure regulating valves are usually provided with a return outlet con nected to permit recirculation of fuel to the fuel supply source, the amount of fuel flowing in the return line being usually determined by the input pressure acting on'the pressure regulating valve. One example of such prior art systems is that disclosed in United States Letters Patent No. 2,000,733 for Burner Installation'f or Domestic Boilers, issued to E. G. Avery.

For optimum efliciency of operation, it is desirable to supply fuel to the atomizing' nozzle at constant rate, either at constant pressure or at constant weight or volume of fuel per unit of time. In prior systems controlled by conventional pressure regulating valves, changes in viscosity of the oil resulting from the natural swing or hunt of the oil temperature control mechanism controlling the oil pre-heater, and the variation of oil analysis from one delivery to the next, prevent the maintenance of a constant firing rate. Also in such prior systems, variation of pressure on the discharge or nozzle side of the pressure regulating valve resulting from variations in pipe friction between the valve and the nozzle, changes in fuel viscosity, collection of carbon or dirt particles in the oil ports of 'the nozzle, and minute differences in size of the oil ports in nozzles of nominally identical size changed in the field, as well as changes in the air pressure supplied for fuel atomization resulting from carbon or dirt particles in the air flow passages in-the nozzle, fading of the compressor, replacementof the compressor, or minute differences in size of the air flow passages in nominally identical nozzlesj all produce undesirable variations in the fuel firing rate. The fuel firing rate will also vary in such prior art systems with different grades of fuel oil used. a

It is, accordingly, a primary object of this invention to overcome these and other disadvantages 'of prior fuel regulating systems by providing new and improved ,fuel flow control valves adapted to maintain predetermined fuel flow characteristics over a wide range of operating conditions.

A further important .object'of .thisjl'nvention is theprov vision of new and improved fuel controlv valves including differential pressure sensitivevalve actuating means subjected at one side to-fuel supply s pressure and at the other side to a control pressurejsuch 1as]tonaintain 2,976,885, Patented Mar. 28, 1961 2 predetermined desired fuel flow characteristics over wide ranges of variation of operating conditions.

Another object of the invention is the provision of a novel fuel control valve including means defining a main fuel flow passage having a variable area orifice therein adjustableto desired fuel flow settings-and a fuel by-pass passage having a valve therein actuated by differential pressure responsive means to maintain substantially constant fuel flow at each setting by controlled by-pass of fuel through the by-pass passage.

Still another object is the provision of such valves wherein the differential pressure responsive means is subjected at one side to fuel pressure upstream of the variable area orifice and at the other side to atmosphere, so as to maintain substantially constant fuel pressure in the main fuel passage upstream of the orifice.

Yet another object of the invention is the provision of new and improved fuel control valves including means defining a variable area orifice which remains substantially of the same shape for all area settings to thus minimize the effects of fuel viscosity variation and fluid friction.

' A further important object of this invention is to provide a fuel control valve of the character mentioned with a differential pressure responsive means having a connection on the control side thereof adapted either to flush out the burner supplyline or to return leakage fluid to a fluid return line leading to the fuel supply reservoir.

Still another object of thisinvention is to provide a fuel control valve of the character mentioned with a piston type differential pressure responsive means capable of efficient long life operation. i V

Also an object of the invention is the provision of novel fuel flow control valves characterized by simplicity of structure, economy of manufacture and long trouble-free service life.

These and other objects, features and advantages of the invention will become apparent as the description proceeds in connection withthe appendedclaims and accompanying drawings wherein like reference numerals have been used to designate like parts and wherein:

Figure 1 is a diagrammatic view of a fuel circulating system incorporating improved fuel control valves embodying the invention; i

Figure 2 isa partially sectional view of one of the valves of the circulating system of Figure 1 connected to function as a constant pressure valve;

Figure 2A is a fragmentary sectional view illustrating the differential pressure responsive means of Figure 2 in fuel by-passing position;

Figure 3 is a sectional view of an adaptation of the fuel control valve of Figure Zillustrating a preferred pressure responsive 1, oil is supplied to this system from an inlet conduit 10- through an oil strainer 12 to an oil pump 14. Oil pump 1 14"f01ces oil through an oil preheater 16 and thence through conduit 17 to a constant pressure valveflS made in accord with this invention. Valve 18 is provided with an inlet connection 20, an outlet connection 22 to the burner, and a return outlet connection zd for oil rec'irculation. .A return conduitf26 is connected between outlet 24 and conduit 10. An oil recirculatingvalve 27 is shown mounted as ansend adapter oftheoil injector assembly '28 and is provided with a fuelinlet 29 .con-

nected by conduit 30 to outletlzz of the constant pressure valve 18, a fuel conducting tube 31 leading directly to the nozzle 32 of the fuel injector assembly 28, and a fuel return outlet 33 suitably connected through conduit 34 to the fuel return line 26.

Recirculating valve 27 and the associated burner structure may be of the type disclosed in our aforesaid copending application S.N. 213,068, and is operable to direct fuel flow entering through its inlet connection 29 either to the fuel tube 31 of burner nozzle 32 or to the fuel return outlet 33 for recirculation through the fuel supply system during periods of inoperation of the burner.

The temperature of the oil supplied to the constant pressure valve 18 through inlet 29 is controlled at the oil preheater 16 which may be a heat exchanger unit of generally conventional design. In the preheater here disclosed, steam is supplied from an inlet 35 through a valve 36 actuated by a regulator 38. Steam condensate is removed from the oil preheater 16 through pipe 39, steam trap 42, and pipe 44. Regulator 38 is connected through cable 46 to a thermal responsive element Within coupling 48 in line 17 so that the supply oil temperature controls the degree of oil preheat. Due to the lag in this control, the supply oil temperature will fluctuate about an established operating norm.

The structural details of one form of constant pressure valve 18 are illustrated in Figure 2. The body 50 of this constant pressure valve 18 is formed with two chambers 52 and 54 interconnected by a series of longitudinal passages 56. Oil inlet connection 20 opens directly into chamber 52. Two outlet chambers 58 and 60 are formed within the body structure 50 intermediate the chambers 52 and 54. A bore 59 connects chambers 52 and 60, and a bore 61 connects chambers 54 and 58. A valve stem 62, having at least one longitudinally extending groove 63 of changing size formed on its outer surface, is mounted for axial sliding movement in bore 59. Valve stem 62 is shown in Figure 2 in its closed position, that is with groove 63 out of communication with inlet chamber 52 and a stop ring portion 65 abutting against the body as shown. As valve stem 62 is moved down through bore 59, groove 63 forms an intercommunicating channel between chambers 52 and 60 to permit passage of oil from inlet 20 to outlet 22 and the burner. Since the size of groove 63'varies along its length, the quantity of oil flow can be accurately controlled by the longitudinal position of valve stem 62. Valve stem 62 extends below the valve assembly 18 and is connected to a clevis 66. Leakage of oil along the valve stem 62 is prevented by a substantially conventional stufiing box assembly 68 including spring 79 and packing material 72. The position of valve stem 62 may be varied either manually or by any suitable conventional automatic controlling mechanism for controlling the quantity of fuel flow through outlet connection 22 to the fuel injector assembly 28.

A valve member '76 has a neck 77 and a conical tip 77 adapted to be disposed in bore 61 and actuated in response to oil pressure at the inlet 20. Its purpose is to control recirculation of oil in the system. Oil from chamber 52 passes through passages 56 into chamber Valve member 76 is fixed to the movable end of a pressure control bellows 7 8 and may be adjustably preloaded by a spring 89 therein. The preloading adjustment of the valve 76 is controlled by manipulation of screw 32 to vary the initial compression of spring sththisscrew being provided with a lock nut 34 to hold the adjustment. The interior of bellows 78 in this use of the valve is open to atmosphere through a port or other opening 79 through the top closure plate 86 of valve body 5%.

In operation. the constant pressure valve 18 is effective to vary the rate of flow through the return outlet connection 24 to maintain the oil inlet pressure within chainber 52 substantially constant regardless of the selected or set position of the valve stem 62. When oil circula tionl starts the oil pressure built up in chamber 54 4 eventually overcomes the resistance of bellows 78 and spring to raise valve neck 77 out of bore 61 (see Fig- -ure 2A) and permit flow of oil through bore 59, chamber 58 and outlet return connection 24. A stable condition is soon reached for a given pump pressure corresponding to desired oil pressure in chamber 52 which results in a certain throttling position of conical tip 77 in bore 61.

Suppose the oil pressure in chamber 52 increases and undesirably tends to increase the fiow of oil through burner outlet 22. The pressure increase is transmitted through passages 56 to chamber 54 to further collapse bellows 78 and further open bore 61 to increase the flow of oil into chamber 58, thereby effectively reducing the oil pressure in chambers 54 and 52 until the desired oil feed pressure is restored in chamber 52. The same but opposite action takes place when the oil pressure in chamber 52 becomes reduced.

Figure 3 illustrates a preferred form of constant pressure valve which differs from that just described principally in its use of a piston type pressure responsive element in preference to the bellows or Sylphon element of Figure 2.

Constant pressure valve 90 of Figure 3 comprises a valve body or casing 92 formed with two inlet chambers 94 and 95 interconnected by a series of longitudinal passages 97, and with two outlet chambers 99 and 100. Fuel flow to outlet chamber 99 from inlet chamber 94 is controlled by a valve stem 102 which is slidable in a bore 194 in the valve body and is provided with one or more longitudinal grooves 106 of tapering width as shown. Valve stem 102 extends to the exterior of the valve casing and may be provided at its outer end with suitable means such as the biasing spring 108, cam follower head 109 and bearing means 110 shown, for coaction with suitable manual or automatic control mechanism (not shown) which may be of conventional type.

The pressure responsive by-pass valve assembly 112 in Figure 3 includes a valve member 114 having a neck portion 116 and conical tip portion 117 adapted to engage in a bore 119, interconnecting inlet chamber 95 and out let chamber 100. Valve member 114, through its tip 117, controls fuel flow between these chambers. The control obtained is responsive to the pressure difference across valve member 114 which constitutes a. piston type differential pressure sensitive element slidable in bore 121 in a valve guide member 123 secured in the upper end of valve body 92. Valve member 114 is downwardly biased by a spring 125 so as to, normally close flow passage 119, the pre-load applied by spring 125 being readily adjustable through an adjustment screw 127 threadedly received in a bore in guide member 1237 After proper spring ad justment or re-adjustment has been effected, the adjustment mechanism preferably is sealed against fluid leakage outwardly along the adjustment screw by provision of a cap nut 129 threaded onto guide member 123 into engagement with a gasket as illustrated.

Since the-re may be some slight leakage of fluid about the piston surfaces of valve member 114, particularly if the oil ports in the burner nozzle should become clogged or if for other reasons pressure in inlet chamber 95 should become excessive, the space 139 within guide member 123 above the piston 114 preferably is connected through outlet fitting 131 to an oil return line or elsewhere as will hereinafter be described with. particular reference to Figure 4.

The mode of operation of the constant pressure valve of Figure 3 is substantially like that of Figure 2. The improved construction of the Figure 3 valve, however, affords longer and more satisfactory service and complete freedom from the possibility of rupture of bellows and like pressure sensing elements with consequent leakage of fuel and repair costs.

Referring HOWtO Figure 4, a modified fuel supply systemis'shown' wherein'the fuel recirculating valve 133corresponding to valve 27 in Figure 1 is separate from the burner head assembly 135 and is of solenoid actuated type. The recirculating valve 133 of Figure 4 functions in substantially the same manner as that of Figure 1, to direct fuel flow entering through its supply line 30 from pressure regulator 90 either through conduit 134 to the burner head 135 or to a conduit 137 connecting into fuel return line 26 for recirculation through the supply system.

As noted above, constant pressure valve 90 may have its outlet fitting 131 from the space above piston 114 (Figure 3) connected into the fuel return line 26 as by a conduit 139, vent means 141 preferably being provided as shown in the return line to assure that pressure above the valve piston remains atmospheric.

Suitable valve actuator means such as cam 143 and camshaft 145 may be provided, the camshaft being rotatable either manually or automatically to control rate of flow through the valve responsive to the constant pressure maintained within it.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. In a fuel supply system for a fluid fuel burner, a fuel flow control valve comprising a body structure having formed therein a first inlet chamber, first and second outlet chambers and a second inlet chamber spaced in that order serially along the length thereof, a first passage means in said body structure interconnecting said first and second inlet chambers, a second passage means in said body structure interconnecting said first inlet chamber and said first outlet chamber, means providing a selectively variable orifice in said second passage means, means selectively operative independently of the pressure of the fiuid in any of said chambers for actuating said variable orifice providing means to vary the size of the orifice in said second passage, and means for maintaining the fluid pressure at the upstream side of said variable orifice providing means in a predetermined relation to a second pressure at all settings of said variable orifice providing means, said last named means comprising a third passage means in said body structure interconnecting said second inlet and said second outlet chamber and providing a valve passage, a valve member in said second inlet chamber cooperating with said valve passage to control fuel flow to said second outlet chamber, and movable wall means defining at least a portion of the Wall of said second inlet chamber and subjected at one side to the pressure in said second inlet chamber and on the other side to said second pressure and operatively connected to said valve member to modify the proportional flow of fuel through said second and third passage means.

2. The fuel flow control valve defined in claim 1 wherein said movable wall means comprises a bellows element mounted in said second inlet chamber with its exterior subjected to fuel pressure in that chamber and its interior open to atmosphere whereby said second pressure is at mospheric pressure so as to maintain substantially constant pressure in said first and second inlet chambers by controlled by-pass of fuel through said third passage means to said second outlet chamber.

References Cited in the file of this patent UNITED STATES PATENTS 862,867 Eggleston Aug. 6, 1907 1,585,732 Otto May 25, 1926 1,661,450 Van Sant Mar. 6, 1928 1,899,396 Ray Feb. 28, 1933 1,980,478 Frentzel Nov. 13, 1934 1,985,279 Buller Dec. 25, 1934 2,070,411 Powers Feb. 9, 1937 2,178,223 Czornecki ,Oct. 31, 1939 2,448,429 Henry Aug. 31, 1948 2,573,724 Neal Nov. 6, 1951 2,616,254 Mock Nov. 4, 1952 2,781,049 Binford et al Feb. 12, 1957

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