Patent GB-744781-A (GB)
Title: A constant flow valve for use in fuel supply systems for liquid fuel burners
IPC: F23D11/28
Filed: 1952-01-07
Abstract: 744,781. Supplying liquid fuel to burners. ORR & SEMBOWER, Inc. Jan. 7, 1952 [Feb. 28, 1951], No. 12273/53. Divided out of 744,747. Class 75(1). [Also in Group XXIX] A fuel supply system for a liquid fuel burner comprises a constant flow valve having a fuel passage therethrough defining an orifice of variable size adjustable to set a preselected rate of flow at the outlet of said passage, and means for maintaining said fuel flow rate constant comprising a fuel return outlet connected to said fuel passage upstream of said orifice by a return passage and a differential pressure responsive device connected across said orifice and adapted to vary the fuel flow through said return passage in response to changes in pressure differential across said orifice. The valve illustrated in Fig. 2 comprises body members 200, 228 rigidly secured together, an inlet 182 and an outlet 184 formed in the member 200 communicating respectively with chambers 202, 204 at opposite sides of a disc 206 having an orifice 208. The tip 217 of a needle valve 216 coacts with the orifice 208 and is adjustable either manually or by automatic mechanism to control the oil flow through the member 200. In operation the pressure drop across the orifice 208 is applied through bores 230, 231 and 250, 251, respectively, to the interior and exterior of a bellows 246 within a housing 240 secured to the body 228, to determine the setting of a valve member 235 controlling a bore 234 leading to an oil return outlet 186. An increase of oil flow through the inlet 182 increases the pressure drop across the orifice 208 which actuates the valve member 235 to permit a larger oil flow to the return outlet 186 whereby the flow through the orifice 208 decreases, resulting in a balanced condition of constant flow. Initially a spring 253 holds the valve member 235 on its seat until a desired pressure drop is established across the orifice 208, determined by adjustment of the spring 253 by a screw 254. The alternative valve construction illustrated in Fig. 4 comprises body members 400, 404, 408 and 458, secured together, an inlet 304 and an outlet 306 being provided in the members 400, 408, respectively. An aperture 416, counterbored to form a thin edge 417, in the end wall 414 of the member 404, defines an orifice through which oil flows from the inlet 304 to the outlet 306, and the effective size of which is variable by means of a rotary valve member 418 having a V-shaped notch 420, the sides of which slope to form a knifeedge 422. The member 418 is in contact with the upper. surface of the member 404 and is mounted for pivotal movement about a pivot pin 424 by means of a lever 428 secured to a shaft 430 having V-shaped notches at its lower end for engagement with radial pins 436 on a stem 434 fixed to the upper surface of the member 418. A by-pass is provided from the inlet 304 to an outlet 308 in the body member 458, said by-pass including bores 460, 462, recess 464, aperture 482, and an outlet chamber 468, and also including a flow path from the recess 464 through bores 476 in the member 458 to an annular chamber 474 between the wall of a recess 467 and a part 472 of a member 470 closing said recess 467, and thence through the part 472 via radial and axial bores 480, 478 into the outlet chamber 468. The flow through the by-pass is controlled by a valve actuated by a bellows 500 responsive to the pressure drop across the orifice 416 applied through bores 460, 462 and 534, 536, respectively, and comprising a valve member 486 having spaced valve faces 488, 490 co-acting with the bore 478 and the aperture 482, respectively. The valve is held closed initially by a spring 522 the compression of which is adjusted by a screw 526 to determine the pressure drop which must be established across the orifice 404 before the valve will open. The two faced valve construction eliminates the effect of any undesired pressure change at the outlet 308. Specification 744,782 and U.S.A. Specification 2,000,733 are referred to.