US3444874A - Fuel supply control systems - Google Patents

Description

May 20, 1969 B. E. SPARKS 3,444,874

FUEL SUPPLY CONTROL SYSTEMS Filed June 21, 1966 Fgj United States Patent 3,444,874 FUEL SUPPLY CONTROL SYSTEMS Brian Edmund Sparks, Shrewley Common, England, assignor to Joseph Lucas (Industries) Limited, Birmingham, England, a British company Filed June 21, 1966, Ser. No. 559,225 Int. Cl. F02c 9/08; Gd 13/32 US. Cl. 137-36 2 Claims ABSTRACT OF THE DISCLOSURE This invention relates to fuel supply control systems for engines such as aircraft gas turbine engines, the system including a variable output pump, a throttle valve, and engine speed sensitive means whereby the pressure drop across the throttle valve can be varied in accordance with engine speed.

The object of the invention is to provide a fuel supply control system of the kind referred to in a convenient form.

According to the present invention, a fuel supply control system for an engine has a variable output pump, a throttle valve, and an engine driven hydraulic signal generator capable of producing a signal which is a function of engine speed and a further valve to which this signal is applied to cause it to control the flow of fuel from the throttle valve to the engine.

The invention will now be described with reference to the accompanying drawings in which:

FIGURE 1 is a diagrammatic representation of one form of the apparatus, and

FIGURE 2 is a diagrammatic representation of asimilar form of the apparatus with certain additional features.

The constructions shown are concerned with fuel supply systems for aircraft gas turbine engines, and include a pump 10 of the variable swash plate type, the swash plate 11 of which is connected to apiston and cylinder type servo mechanism 12. The system also includes a throttle valve 13 in the outlet from the pump 10 and a further valve 14 disposed downstream of the throttle valve 13. Although illus trated diagrammatically, the throttle valve 13 may itself be of the kind referred to as a variable metering orifice and may be rotated to avoid static friction, as may the valve 14.

The system also includes a centrifugal pressure generator indicated at 15, this being of the kind comprising a disclike component having a plurality of radially extending passages, and a central axially extending passage communicating with the radial passages, the component being connected to the engine to be driven at a speed which is directly proportional to the engine speed. The external peripheral space within the centrifugal pressure generator 15 is in communication through the pipe-line 16 with the up stream side of the throttle valve 13, whilst the central pass age of the centrifugal pressure generator is in communication through the passageway 17 with the further valve 14. The opposite side of the latter valve is connected to the ice downstream end of the throttle valve 13, and controls the fiow of fluid from the downstream side of the throttle valve 13 through a restricted orifice 18 to a pipe-line 19 leading to the burners of the engine (not shown).

In use, the pressure drop across the throttle valve 13 is controlled in accordance with engine speed derived from the centrifugal pressure generator 15 by the further valve 14 and it is desirable in this instance that the pressure drop across the throttle valve 13 shall be porportional to the square of the engine speed.

In order to compensate for changes in density of the fuel being pumped, the system as shown in FIGURE 2 incorporates an hydraulic potentiometer comprising a fixed restricted orifice 20, and a variable restricted orifice 21, the latter being adjustable in response to changes in the fuel temperature and also possibly having an adjustment for compensating against changes in density of different grade of fuel. The system shown in FIGURE 2 also incorporates a bleed passage 22 whereby air in the centrifugal pressure generator 15 can be bled from the system. In use, the further valve 14 is subjected to the mean pressure of the potentiometer.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A fuel supply control system for an engine comprisin g a variable output pump, passage means from the pump to the engine, a manually controllable throttle valve in the passage means, a further valve in series with the throttle valve in the passage means, between the throttle valve and the engine, and an engine driven hydraulic signal generator arranged to produce an engine speed responsive hydraulic signal, and further passage means affording communication between the generator and the further valve, whereby said signal can reach the further valve to vary the fuel flow therethrough to the engine.

2. A fuel supply control system for an engine comprising a variable output pump, passage means from the pump to the engine, a manually controllable throttle valve in the passage means, a further valve in series with the throttle valve in the passage means, between the throttle valve and the engine, and an engine driven hydraulic signal generator arranged to produce an engine speed responsive hydraulic signal, and further passage means affording communication between the generator and the further valve, the further passage means including a first passage between the generator and the further valve, 2. variable restrictor in the first passage, a second passage between the further valve and the passage means at the upstream side of the throttle valve, and a fixed restrictor in said second passage.

References Cited UNITED STATES PATENTS 2,454,565 11/ 1948 Peterson 137-36 2,642,275 6/ 1953 Sollinger 137-36 2,857,150 10/1958 Sharp 137-36 3,028,847 4/1962 Sterner 137-36 X 3,194,252 7/1965 Locher 137-34 X 3,199,522 8/1965 Cramer 137-34 X 3,242,936 3/1966 Kalb 137-34 X 3,347,103 10/1967 High 73-521 X CLARENCE R. GORDON, Primary Examiner.

US. Cl. X.R.

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