US2722894A - Fuel pump governor - Google Patents

Description

QL A

Nov. s, 1955 2,722,894v

R. J. IF IELD FUEL PUMP GOVERNOR Filed Jan. 24, 1950 2 Sheets-Sheet l Nov. 8, 1955 R. J. [FIELD FUEL PUMP GOVERNOR 2 Sheets-Sheet 2 Filed Jan. 24, 1950 N w i L2/U' eli/"bof eflfb'ei/ UnitedStates Patent O FUEL PUMP GOVERNOR Richard Joseph Itield, Dural, Australia, assignor to Joseph Lucas Limited, Birmingham, England Application January 24, 1950, Serial No. 140,225

Claims priority, application Great Britain February 9, 1949 3 Claims. (Cl. 10S-162) This invention has for its object to provide an improved fuel pump governor for regulating the supply of liquid fuel to jet-propulsion engines, gas turbines, or other prime movers.

The invention comprises in combination with a rotary fuel pump, a liquid fuel outlet, a liquid-operated servomechanism for regulating the rate of supply of liquid fuel from the pump to the outlet, a vent valve for controlling the servo-mechanism, a spring loaded movable member for actuating the vent valve in response to the action of opposed liquid pressures which are respectively correlated with the speed of the pump and the pressure of the liquid fuel supplied by the pump to the outlet, a passageway for conducting to one side of the said member liquid fuel at a pressure correlated with the speed of the pump, a second passageway for conducting to the other side of the said member liquid fuel at a pressure correlated with that at which the fuel is supplied to the outlet, a restricted outlet in communication with the second passageway, and an adjustable throttle in the second passageway for determining the liquid fuel pressure exerted on the last mentioned side of the said member.

In the accompanying drawings:

Figures 1 and 2 are part sectional side elevations illustrating two embodiments of the invention.

Referring to Figure 1, this illustrates an application of the invention to a rotary liquid fuel pump A of the swashplate type and of known construction. The pump comprises a rotor a mounted in a hollow body part b. Liquid fuel is supplied to the body part from a supply source through an inlet connection at c leading to a suction port d. Liquid is discharged by the pump through a port e leading to an outlet connection at f. In the rotor a are formed a plurality of bores each containing a reciprocatory plunger g which at its outer end co-operates with a swash-plate 20. During rotation of the rotor each bore receives liquid fuel from the port d and later the liquid is discharged by the plunger through the outlet f. For varying the strokes of the plungers and hence the output of the pump, the obliquity of the swash-plate 20 is varied by a liquid-operated servo mechanism B of known form, and incorporated with the pump body part. This mechanism consists of a piston h slidable in a cylinder z' and loaded by a spring j. From the piston extends a rod k for actuating the swash-plate 20. One end of the cylinder z' is in communication with the discharge port e and the other end is in communication with the same port through a restricted orifice m contained in a passage n. The latter end of the cylinder also communicates by way of a passage o with the seating p of a vent valve, the latter comprising a closure member q carried by a lever r. When the closure member q of the vent valve'is closed, the liquid pressures in the two ends of the cylinder are equal, and the spring j moves the piston h to the right for increasing the obliquity of the swash-plate 20, and thereby increasing the pump output, the swash-plate being shown in its position of maximum obliquity. But when the closure member q of the vent valve is opened, it relieves the liquid pressure in the left hand end of the cylinder i, and the predominating liquid pressure then existing in the right hand end of the cylinder moves the piston h to the left for reducing the obliquity of the swash-plate 20, and thereby reducing the pump output.

In carrying the invention into effect as shown in Figure l, there is formed in the body part a a chamber s which contains the above mentioned vent valve and lever, the chamber being bounded on one side by a flexible diaphragm twhich is attached to one end of the lever r.

The chamber s communicates with the pump inlet connection by Way of a passage u containing a restricted orilice v. Also the said chamber communicates with the pump delivery passage by way of a passage w which contains an adjustable throttle x.

At the outer side of the diaphragm tis formed another chamber 2 by means of a cover piece 3, this chamber being in communication with the portion of the pump body part containing the rotor a by way of a passage 4. Also the cover piece 3 is adapted to accommodate a spring 6 which at one end is attached to the diaphragm and which at the other end is attached to an adjustable anchorage 7 carried by the cover piece.

In this example it is desired that one side of the diaphragm shall be subject to a liquid pressure related to the speed of rotation of the pump rotor a, the latter deriving its motion from the prime mover to which fuel is supplied by the pump. To meet the said reqmrement, the rotor is provided (in known manner) with a passage 8 leading from an axial bore 9 in the rotor to the region around the rotor, the bore 9 being supplied with liquid from the pump inlet c. Due to the centrifugal action of the rotor on the liquid in the passage 8, this liquid is discharged to the said region and thence along the passage 4 to-the outer side of the diaphragm t at a pressure which is related to the rate of rotation of the rotor a.

With the arrangement above described, the diaphragm t is subject at its opposite sides to two liquid pressures satisfying the requirements of the invention, the one pressure being related to the speed of rotation of the pump rotor (which in turn is related to the speed of the prime mover which actuates the pump), and the other being related to the pressure of the liquid supplied by the pump. The latter pressure (which is a fraction of the pump delivery pressure) is determined by the size of the orifice v and the setting of the throttle x. ln this respect it will be seen that the throttle x controls the admission of liquid fuel to the chamber s, whilst the restricted orice v controls the discharge of liquid fuel from this chamber. Consequently, the liquid pressure in the chamber s depends on the ratio of the throttle opening and the restricted orifice as well as the pump delivery pressure, and (due to the discharge through the restricted oriiice) is only a fraction of the pump delivery pressure. It will be appreciated that the pump delivery pressure is considerably greater than the pressure related to the speed of the pump rotor. Consequently, it is necessary for the pressure in the chamber sto be only a fraction of the pump delivery pressure, and this is attained in a simple and satisfactory manner by the orifice v and the throttle x.

The arrangement is such that when the pressure in the chamber 2 exceeds that in the chamber s by a predetermined amount (which is variable by the adjustment of the spring 6), the lever r is actuated for opening the associated vent valve, so causing the servo mechanism to reduce correspondingly the pump output.

In the above described example, the liquid pressure in the chamber s opposes liquid flow through the vent valve when the closure member q is open. However, such opposition to the liquid flow through the vent valve can be avoided, if desired, by employing the arrangement shown in Figure 2 in which the liquid pressure in the chamber s is the same as that at the pump inlet d. In this example, a double diaphragm consisting of a pair of interconnected diaphragms t, t1 of different diameters or different effective areas is used, the by-passed liquidbeing conveyed to theregion t2 between the diaphragms by the passage w which extends through the diaphragm t1 at t4. The pressure of the liquid supplied to the region between the diaphragms is variable` by a throttle x and also by an adjustable spill valve 10; The spill valve 10 leads to the chamber s at. a position in the passage w between the throttle x and the region t2 separating the diaphragms so that the liquid pressure in this region is only a fraction of the pump delivery pressure. The chamber s is in this example open by way of an unobstructed passage u to the inlet side of the pump, the above mentioned restricted orifice v (Figure 1) being. omitted. In other respects the example shown in Figure 2 is similar to that shown in Figure 1.

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

l. A governor for a rotary liquid fuel pump comprising in combination with the pump, a liquid fuel outlet, a liquid-operated servo-mechanism for regulating the rate of supply of liquid fuel from said pump to said outlet, a vent valve for controlling said servo-mechanism, a spring loaded movable member for actuating said valve in response to the action of opposed liquid pressures which are respectively correlated with the speed of said pump and the pressure of the liquid fuel supplied by said pump tosaid outlet, a passageway for conducting to one side of said member liquid fuel at a pressure correlated with the speed off said pump, a second passageway for conducting to the other side of said member liquid fuel at a pressure correlated with that at which the fuel is supplied to said outlet, a restricted outlet in communication with saidsecond passageway, and an adjustable throttle inA said second passageway for determining the liquid fuel. pressure exerted on the last mentioned side of said member.

2. A governor for a rotary liquid fuel pump comprising in combinationwith the pump, a liquid fuel outlet, a liquid-operated servo-mechanism for regulating the rate of supplyr of liquid fuel from said pump to said outlet, a hollow body part, a movable member contained in said body part and responsive to the action of opposed liquid pressures which are respectively correlated with the. speed ofI said pump and the pressure of the liquid fuel supplied by said pump to said outlet, a vent valve operable by said member for controlling said servomechanism, a spring acting on said member, a'. chamber situated at one side of said member and containing said vent valve, a passageway for conducting to the side of said member remote from said chamber liquid fuel at a pressure correlated with the speed of said pump, a second passageway for conducting to said chamber liquid fuel at a pressure correlated with that at which fuel is supplied to said outlet', an adjustable throttle in said second passage for determining the fuel pressure in said chamber, and a third passageway leading from said chamber and provided with a restriction.

3. A governor for a.rotary liquid fuel pump comprising in combination with the pump, a liquid fuel outlet, a liquid-operated servo-mechanism for regulating the rate of supply ofli`quid` fuel from said pump to said outlet, a hollow body part, a pair of spaced and interconnected movable members contained in said body partand responsive to the action of opposedliquid pressures which are: respectively correlatedwith the speed. of said pump and the pressure of liquid fuel supplied by said pump tosaidoutlet,. avent valve operable by said membersfor controlling. said servo-mechanism, a spring acting on said members, a chamber situated at one side of said members and containing said vent valve, a passageway for conducting to the side. of said members remote from said chamber. liquidfuely at a pressure correlated with the speed of said pump, a. second passageway for conducting to the region between said members liquid fuel at a pressure correlated with that at which the fuel is supplied to-said outlet, an adjustable throttle in said second passageway for determining the fuel pressure in the region between saidmembers, ar spill valve affordingy restricted communication between said second passagewayand said chamber, and av third passageway leading from said chamber.

References Cited in the file of this patent UNITED STATESPATENTS 2,407,013 Ield Sept. 3, 1946 2,424,035- Iield'v V Iuly l5, 1947 2,429,005 Watson' et al. Oct. 14, 1947 2,442,954 Lee June 8, 1948 2,451,055; Beacham Oct. 12, 1948 2,581,276 Mock Ian. 1, 1952 FOREIGN PATENTS 959,467 France Oct. 3,' 1949

Images