US3160104A

US3160104A - Rotary fuel pump of the kind including cam-operated pistons

Info

Publication number: US3160104A
Application number: US149746A
Authority: US
Inventors: Barnard Mark Cary Sedgwick
Original assignee: Rover Co Ltd
Current assignee: Rover Co Ltd
Priority date: 1960-11-08
Filing date: 1961-11-02
Publication date: 1964-12-08
Anticipated expiration: 1981-12-08
Also published as: CH376718A; GB926937A; DE1200071B

Abstract

926,937. Gas turbine plant; balancing. ROVER CO. Ltd. Nov. 3, 1961 [Nov. 8, 1960], No. 38263/60. Classes 110 (3) and 122 (3). [Also in Group XXVIII] In a swash plate fuel pump (see Group XXVIII) for a variable-speed gas turbine engine and having a revolving cylinder block 27, Fig. 6, driven by the engine, the block engages a stationary valve face 23 with arcuate inlet and outlet ports, the outlet port being divided into two portions 2 and 3, Fig. 2, which deliver into separate burner supply conduits. Outlet portion 2 is longer and delivers more fuel than portion 3. The delivery from outlet 2 is also connected to centrifugally-actuated valves 7 and 8, Fig. 2 (40 and 44 in Figs. 6 and 8) which open when predetermined engine speeds are exceeded to by-pass the delivery from outlet 2 to the pump inlet. Valve 7 is set to limit the maximum engine speed and valve 8 is manually controlled through pistons 54 and 48, Figs. 6 and 8 (8a in Fig. 2) to control the engine speed up to said maximum. In one arrangement, Fig. 2, when increase in speed is required, valve 8 is held closed so that both ports 2 and 3 deliver to burner 11. When the desired speed is reached or deceleration is required, valve 8 is released and delivery from port 2 by-passed, check valve 9 closing and only port 3 delivering to burner 11. For further reduction in fuel supply a valve 10 may be opened to by-pass part of the delivery from port 3. As an alternative to valve 10 and to compensate for altitude changes, the pump delivery may be varied by rotating the swash plate 31 relative to ports 1, 2, 3 thereby varying the relative outputs of these ports. A balance weight 43 is provided on the revolving cylinder block 27, Fig. 8. Specification 819,463 is referred to.

Description

Dec. 8, 1964 M. c. s. BARNARD 3,160,104

ROTARY FUEL. PUMP OF THE KIND INCLUDING CAM-OPERATED PISTONS Filed Nov. 2, 1961 4 Sheets-Sheet l FIGl.

FUEL FLOW 0 TO BURNER.

INLET-w Dec. 8, 1964 M. c. s. BARNARD 3,160,104

ROTARY FUEL PUMP OF THE KIND INCLUDING CAM-OPERATED PISTONS Filed Nov. 2, 1961 4 Sheets-Sheet 2 DISCHARGE SUCTION H615.

Dec. 8, 1964 M. c. s. BARNARD 3,160,104

ROTARY FUEL PUMP OF THE KIND INCLUDING CAM-OPERATED PISTONS Filed Nov. 2, 1961 4 Sheets-Sheet 5 BBYIII Dec. 8, 1964 M. c. s. BARNARD 3,160,104

ROTARY FUEL. PUMP OF THE KIND INCLUDING CAM-OPERATED PISTONS Filed Nov. 2, 1961 4 Sheets-Sheet 4 2 2 95 fiTbS United States Patent O ROTARY FUEL PUMP OF THE KIND INCLUDING CAM-OPERATED PISTONS Mark Cary Sedgwicir Barnard, Solihull, England, assignor to The Rover Company Limited, Solihull, England Filed Nov. 2, 1961, Ser. No. 149,746

Claims priority, application Great Britain, Nov. 8, 1960,

6 (Ilaims. '(Cl. 103-41) The invention relates to a fuel pump of the kind comprising a rotor having a plurality of axially-extending bores, each containing a piston of which one end extends from the bore and is urged by a spring into abutment with a cam-plate inclined to the axis of rotation of the rotor, the bores having open ports at the ends thereof remote from the pistons and being circumferentially-spaced around the axis of the rotor so that, during rotation of the rotor, the open port of each bore passes successively a fuel inletand a fuel outlet in the form of circumferentially-spaced arcuate apertures, co-axial with the rotor and positioned in a stationary thrust face co-acting with the end face of the rotor containing the open ports of the bores.

Hitherto the arcuate length of each of the inlet and outlet apertures has been almost 180, the two apertures being separated by a land of arcuate length not greater than the diameter of the ports.

According to the invention, a fuel pump of the above kind has at least one of the inlet and outlet apertures divided into two or more circumferentially-spaced arcuate portions by a separating land of arcuate length not greater than the diameter of the ports.

In one form of the invention, the fuel pump has a single inlet aperture and the outlet aperture is formed by two circumferentially-spaced arcuate portions, separated from each other and from the inlet aperture by lands each of arcuate length not greater than the diameter of the ports. One of the outlet portions may be shorter than the other portion, so that the flow through the said one portion will be smaller than the flow through the said other portion.

Such a pump is suitable for a variable speed gas turbine engine, as it gives two separate deliveries from a single pumping unit. On acceleration of the engine, when a larger flow of fuel to the burners is required, the output of both outlet portions together can be fed to the burners; but on deceleration, when the fuel supply must be accurately controlled due to the very weak fuel-air mixtures then existing, the output from the arcuately-shorter portion only may be fed to the burners.

By way of example, a fuel pump for a variable speed gas turbine engine and having two delivery apertures in accordance with the invention, will be described herein with reference to the accompanying drawings, in which: FIGURE 1 is a typical fuel supply characteristic of the fuel pump; I

FIGURE 2 is a diagram showing the stationary thrust face, which co-acts with the, end face of the pump rotor containing the open ports of the bores, and also showing the fuel circuit leading to a burner of the engine; I

FIGURES 3 to 5 are diagrams showing the effect, on the ratio of the flow of fuel from the two delivery apertures of the pump, of adjustment of the cam-plate of the pump in the circumferential direction;

FIGURE 6 is an axial section through a practical form of the fuel pump and also shows, in section, a fluid-operable actuator for controlling the engine speed;

.URE 6;

r ce

FIGURE 8 is section on the line VIII-VIII inFIG- URE 6; and 7 FIGURE 9 is an end view on the line IX-IX in FIG- URE 6 of the end plate 21, described hereinafter.

FIGURE 1 shows a typical fuelsupply characteristic for the fuel pump. The characteristic is obtained by plotting the flow of fuel to the burner against the rotational speed of the fuel pump, i.e., a function of engine speed, where the fuel pump is driven by the engine. The characteristic has four lines of control, namely (a) Acceleration;

(b) Maximum speed governing, effected by a centrifugally operated valve of the kind shown by reference 40 in FIGURE 8;

(c) Deceleration, and

(0') Minimum speed, or any intermediate speed, governing, effected by a second centrifugally operated valve of the kind shown by reference 44 and engageable by a fluid-operable piston 48 in the pump illustrated in FIG- URES 6 and 8.

Referring to FIGURE 2, the thrust face of the fuel pump is similar to that shown and described in Serial No. 688,646 (filed October 7, 1957), now Patent No. 3,085,619, except that the arcuate outlet aperture is divided into two circumferentially-spaced

arcuate portions

2, 3. In FIGURE 2, the inlet aperture is denoted by reference 1. The outlet aperture 2 communicates through a channel 4 with an annular channel 5, which communicates with a central bore in the rotor shaft, as described in the aforesaid Specification and hereinafter described with reference to FIGURES 6 to 9 hereof, from which bore, fuel can be spilled back to the pump inlet through centrifugally-operable maximum and minimum speed governing valves as aforesaid. In FIGURE 2, the maximum speed governing valve is denoted by reference '7 and the minimum speed governing valve is denoted by reference 8; these being the equivalent of valves 40 and 44 shown in FIGURES 6 and 8 of the present Specification. The part indicated by reference 8a in FIGURE 2 denotes diagrammatically a fluid-operable piston similar to piston 48 in the pump shown in FIGURE 6 and 8 hereof. For simplicity, the valves 7 and 8 are showndiagrammatically in a line 6 leading to the burner 11 from the aperture 2 r' and the passages 4 and 5, instead of acting as spill returns from the aforesaid axial bore. The outlet aperture 12. The aperture 3 also communicates with the pipe 6 through a pipe 13 containing a control valve 10. The flow through the pipe 6 downstream of the junction with the pipe 13 is controlled by a spring loaded non-return valve 9. The

apertures

1, 2, and 3 are separated circumferentially from each other by lands of arcuate length substantially equal to or smaller than the diameter of the ports at the adjacent ends of the bores of the pump. The arcuate length of the lands are not made greater than the diameter of the ports as otherwise there would be discontinuous pumping. The arcuate length of the aperture 2 is greater than that of aperture 3 and therefore the flow through aperture 2 is greater than that through aperture 3.

During acceleration along line a of FIGURE 1, the valves 7 and 8 are both closed and the fuel supplied to the burner 11 is the sum of that delivered by the

apertures

2 and 3 and therefore the total output of the pump is substantially the same as that of a'pump having a single semi-annular outlet aperture. 7

At rotational speeds below the minimum, or intermediate speed to which the valve 8 has been set, the fuel received by the burner will be discharged from both

apertures

2 and 3 via the pipes 6 and 12 respectively. The

valve 9 will beheld open against its spring by the diiference between the pressure of fuel'delivered by the aper- 3

tures

2 and 3. When the minimum, or said intermediate, speed has been reached, the valve 8 will open and some of the fuel discharged by the aperture 2 will be by-passed back to the inlet 'side of the pump. When the valve 8 has opened, the operation of the pump will be along line b. The valve 9 will be closed by its spring and assuming that the valve It is closed, the burner 11 will only receive fuel discharged from the aperture 3 via the pipe 12 and the engine will decelerate along the line 0. When the valve 10 is opened after the valve 8 has opened, part of the fuel flow from the aperture 3 passes through the pipe 13 and is by-passed through the valve 8 to the inlet side of the pump. Thusthe rate of fiow of fuel to the burner 11 will be equal to the rate of flow from the aperture 3 minus the rate of flow through the pipe 13. This has the effect of lowering the line in FIGURE 1; Thus the provision of the valve 10 enables a lower operating line 0 to be selected when the valve 8 is open. Themaximum speed valve 7 is set to open at a higher rotational speed than the valve 3 and will only open when the valve 8 is held closed by the piston 3a. When the valve 7 is open, fuel discharged from the aperture 2 is by-passed through the valve 7 in a similar manner. The valve 19 has no effect on the flow to the burner 11 when the valves 7 and 8 are both closed, as the same flow will reach the burner 11 whether the valve 10 is open or closed.

The cam-plate, which acts on the pistons of the pump is stationary .in the pump shown diagrammatically in FIGURE 2 but alternatively it can be made angularly adjustable in either circumferential direction from a normal position in which an axial plane AB through the cam-plate passes diametrically through the lands between the apertures 1, 2 and 1, '3 respectively, as shown at the left-hand side of FIGURE 3. In that case the valve 10 and the pipe 13 are not required, as will be explained hereinafter. An angularly adjustable cam-plate is shown herein by reference 31 in FIGURES 6 and 7 hereof. The right-hand side of FIGURE 3 is a development diagram showing the flow through the

apertures

1,2 and 3 for all rotary positions of a piston in passing around the thrust I face from A to B and from B to A in the clockwise direction. The suction flow through aperture 1 appears'below the horizontal axis of the right-hand side diagram and the discharge flow through

apertures

2 and 3 appears above the horizontal axis. The relative ratio of the flow through the aperture 3 to the combined flow through

apertures

2 and 3 can be seenby comparing the corresponding areas indicated on the right-hand side diagram.

FIGURE 4 shows the efiect of angularly adjusting the cam-plate in the clockwise direction so that the arcuate length of the aperture 2 over which discharge 'occurs'is reduced. Fromthe right-hand side diagram it will be seen that the ratio of area 3 to area 2+3 is increased.

FIGURE shows the effect of angularly adjusting the cam-plate in the anti-clockwise direction so that the arcuate length of the aperture 3 over which discharge occurs is reduced. From the right-hand side diagram it will be seen that the ratio of area 3 to area 2+3 is decreased. a I

Thus by angularly turning the cam-plate, the ratio of the effective arcuate length of the aperture 3 to thefltotal effective arcuate length of

apertures

2 and 3 is altered and so the inclination of the line 0 in FIGURE lean be increased or decreased. This method of adjustmentcan V be used instead of providing the pipe 13 and the valve 1 as the total flow from the apertures 2 and 3is reduced as will be seenby-comparing the right-hand side diagram of FIGURES 3-5, due to the reduction of the effective arcuate length of the apertures 2m 3.

By splittirig the discharge aperture into two portions in enco es having two or more combustion chambers. 10'

accordance with this invention two separate deliveries can be obtained from a single pump and also as the pump operates efficiently over both portions it is possible to maintain a desired controlover a Wide range of engine conditions, such as varying altitude.

Although the discharge aperture, as described, has been divided into two portions, it may be divided into more than two portions e.g., for use in a gas turbine engine In some cases it may b desirable to divide the inlet aperture into two or more portions. 7

Referring to FIGURES 6 to 8, a practical form of fuel pump having an angularly adjustable cam-plate 31 comprises a substantially cylindrical casing to which

end plates

21 and 22 are attached. The end plate 21 has an inwardly-directed central portion 23, having a bore providing a'bearing for the rotor shaft 24 of the pump. The outer end of the shaft 24 is connected to be driven at 25 from the main shaft'of the engine (not shown), the speed and therefore the output of the pump being a function of the engine speed. The inner end 'of the shaft is flanged at 26 and carries a rotor 27 provided with three bores extending parallel to the axis of the rotor and spaced apart equi-angularly around the rotor. 1 Each bore contains a piston 28. The head of each piston remote from the shaft 24 has a part-spherical recess therein in which is accommodated a ball 29, engaged in a similar recess in a shoe 30 carried on a cam track 31, mounted on a gear wheel also illustrated. they will spill fuel from the central bore 41 back into'the i the combined action of the cam track 31 and the springs Liquid fuel from a reservoir '(not shown) is delivered into the interior of the pump casing 20. The inner end face of the bearing 23 constitutes the aforesaid stationary thrust face and in accordance with this invention it is provided with the arcuate inlet aperture 1 and the arcuate outlet aperture portions 2'and 3, which have been shown in FIGURES 2 to -5 and also appear in FIGURE 9. The inlet aperture 1 communicates through a duct 35 in the bearing 23 with the interior of the pump casing 20. Each time a piston 28 moves to the right, as viewed in FIGURE 6, under the combinedaction of the spring 33 and the cam-plate 31, it will inspire a volume of fuel through the inlet aperture 1 and a communicating port 36 in the liange 26,v into the bore containing the piston 28. Each time a piston 28 moves to the left into the position shown v The outlet aperture portion 2 also communicates through duct 39 in the shaft 24 with a central bore 41 which communicates with the maximum and minimum speed, centrifugally-operable valves 40 and 44, similar to the valves 7 and 8 shown diagrammatically in FIGURE 2. In FIG- URE6, thevalve 44 only is illustrated; butinFIGURE 8, the maximum speed centrifugally operable valve 40 is When either of these valves are open interior of the pump casing 20. Each centrifugallyoperable valve comprisesa half-ball member carried on the end of a leaf spring 42, mounted on a bracket 70 carried on the flange 26:01? the shaft 24; Referring to FIG- URE 8, the rotor 27 also contains a balancingweight 43, arranged equi-angularly with respect to the twohalf-ball valve members of valves 40, 44. I

The maximum speed centrifugally-operable valve 40 "is set toopen at maximum speedand the-minimum speed centrifugally-operable valve '44 is set to openat a predetermined lower speed; but the spring force acting on the valve member of valve 44 is variable by a fluid-operable actuating device, which is arranged to be operated in response to a control member, such as an accelerator pedal of a vehicle driven by the engine or any other suitable throttle control. The rotor 27 has a further bore 45 in the end adjacent the cam-track 31 and communicating through a radial duct 46 with a chamber 47, carried by the rotor 27 and containing a piston 48, which acts on the back of the half-ball valve 44 and so modifies the loading produced by the spring 42. The bore 45 communicates through a pipe 49 with an actuating device, comprising a reservoir 50 for oil or other suitable liquid for actuating the piston 48. A rod 52, connected to the vehicle accelerator pedal or othercontrol, has a ball end 53, which is captive in a piston 54, carrying-a retainer 55, for one end of a compression spring 56 of which the other end reacts on a valve member 57, for sealing a duct 58leading from the reservoir 50. The valve member 57 is carried on a rod 60, having a head 61, guided in a bore 62 of the piston 54. The arrangement of the actuating device is such that when the piston 54 is pushed to the left, as viewed in FIGURE 6, by the rod 52, the duct 58 is closed and oil or other actuating liquid in the space occupied by the spring 56 is expressed through the pipe 49, to vary the pressure acting on the piston 48. When the rod 52 is moved in the opposite direction the head 55 of the rod 60 is carried with the piston 54 to open the duct 58, whereby oil or other actuating liquid can pass from the reservoir 59 to replenish any loss from the working spaces.

As aforesaid, the cam-plate 31 is angularly adjustable, to vary the angular positions of the beginning and end of the suction and discharge strokes of the pistons 28 relatively to the arcuate inlet and outlet apertures and thereby to alter the effective arcuate lengths of the apertures. This is accomplished by mounting the cam-plate 31 on the gear wheel 32 which is engageable by a Worm 65, carried on a shaft 66, having a control end 67 accessible from outside the pump casing. The shaft 66 may be locked in any-desired position by means-of a set-screw 68. (See FIGURE 7.)

The pump shown in FIGURES 6-9 has its delivery outlet from the outlet aperture portion 2 and a further delivery outlet 69 from the'outlet aperture portion 3 (see FIGURE 9) connected to a burner 11 by pipes 6 and 12 as in FIGURE 2, except that the pipe 13 and control valve are not provided. Also the centrifugally-operable valves 40, 44 are provided internally in the pump; instead of in the external positions as shown diagrammatically in FIGURE 2 at 7 and 8. A non return valve 9 is provided in the pipe 6 as shown in FIGURE 2. The valve 40 is set to open at a predetermined maximum speed and the valve 44 is set to open at a predetermined minimum speed; but the piston 48 and the associated actuating device enable the loading on the valve 44 to be varied so that it will open at any intermediate speed. By turn ing the shaft 66, the cam-plate 31 can be angularly adjusted to produce the effect illustrated in FIGURES 3 to 5. As aforesaid, this will have the effect of altering the inclination of the line c in FIGURE 1.

What I claim as my invention and desire to secure by Letters Patent of the United Statesis:

l. A fuel pump comprising a generally cylindrical casing having closed ends, a rotor mounted co-axially within said casing with an annular space between said casing and said rotor, the rotor having a plurality of axiallyextending bores therein, a piston-in each said bore, one end of each said piston extending from the bore in which it is positioned, the bores having open ports at the ends thereof remote from the pistons and being circumferentially-spaced around the axis of the rotor, a cam-plate* inclined to the axis of rotation of the rotor, a spring in each said bore positioned to bias the associated piston v into abutment with said cam-plate, stationary structure forming oneend of said casing and having a thrust face co-acting with the end face of the rotor, containing the open ports of the bores, said thrust face containing a fuel inlet and a fuel outlet means, in the form of circumferentially-spaced arcuate apertures co-axial with the rotor, said fuel inlet communicating with the interior of said casing, said outlet means being divided into at least two circumferentially-spaced, concentric, arcuate portions of the same radius, separated from each other and from said fuel inlet by lands each of arcuate length not greater than the diameter of the ports, at least one centrifugallyoperable by-pass valve, carried by said rotor and communicating with one of said arcuate portions of said outlet means and operable to by-pass at least part of the delivery from said arcuate portion to the interior of said casing at a predetermined rotational speed of said rotor, a fuel supply pipe connection in said casing, whereby fuel is supplied from outside said casing to the interior thereof, and at least two separate delivery ducts in said stationary structure, one of said delivery ducts leading to the outside of said casing from said outlet apertures respectively.

2. A fuel pump comprising a generally cylindrical casing having closedends, a rotor mounted co-axially within said casing with an annular space between said casing and said rotor, the rotor having a plurality of axiallyextending bores therein, a pistonin each said bore, one end of each said piston extending from the bore in which it is positioned, the bores having open ports at the ends thereof remote from the pistons and being circumferentially-spaced around the axis of the rotor, a cam-plate inclined to the axis of rotation of the rotor, a spring in each said bore positioned to bias the associated piston into abutment with said cam-plate, stationary structure forming one end of said casing and having a thrust face co-acting with the end face of the rotor, containing the open ports of the bores, said thrust face containing a fuel inlet and a fuel outlet means in the form of circumferentially-spaced arcuate apertures co-axial with the rotor, said fuel inlet communicating with the interior of said casing, said out- .let means being divided into two circumferentially-spaced,

concentric, arcuate portions of the same radius but of unequal arcuate length and separated from each other and from said fuel inlet by lands each of arcuate length not greater than the diameter of the ports; a maximum speed centrifugally-operable by-pass valve, carried by said rotor and communicating with the longer arcuate portion and operable at a predetermined maximum rotational speed of said rotor to by-pass at least part of the delivery from said longer arcuate portion to the interior of said casing, a minimum speed centrifugally-operable by-pass valve, carried by said rotor and also communicating with the longer arcuate portion and operable at a predetermined rotational speed of said rotor, lower than said maximum speed, to by-pass at least part of the delivery from said longer arcuate portion to the interior of said casing, a fuel supply pipe connection in said casing, whereby fuel is supplied from outside said casing to the interior thereof, and two separate delivery ducts in said stationary structure, one of said delivery ducts leading to the outside of said casing from said outlet apertures respectively.

3. A fuel pump as claimed in claim 2 in which a control member, such as an accelerator or throttle control, is arranged to vary the speed at whichsaid minimum speed bypass valve is operable.

4. A fuelpump comprising a generally cylindrical casing having closed ends, a rotor mounted co-axially Within said casing with an annular space between said casing and said rotor, the rotor having a plurality of axially-extending bores therein, a piston in each said bore, one end of each.

bore positioned to bias the associated piston into abutment of said casing and having a thrust face co-acting with the end face of the rotor, containing the open ports of the. bores, said thrust face containing a fuel inlet and a fuel outlet means in the form of circumferentially-spaced arcuate apertures co-axial with the rotor, said fuel inlet communicating withv the interior of said casing, said outletmeans being divided into at least two circumferentiallyspaced, concentric, arcuate portions of the same radius, separated from each other and from said fuel inlet by lands each of arcuate length not greater than the diameter of the ports, at least one centrifugally-operable by-pass valve, carried by said rotor and communicating with one of said arcuate portions of said outlet and operable to bypass at least part of the delivery fromsaid one of the arcuate portions 'to the interior of said casing at a predetermined rotational speed of said rotor, a fuel supply pipe connection in said casing, whereby fuel is'supplied from outside said casing to the interior thereof, and at least two separate delivery ducts in said stationary structure, one of said delivery ducts leading to the outside of said casing from each portion of said outlet means, said cam-plate being angularly adjustable about the axis of rotation of said rotor, whereby to vary the angular positions of the beginning and end of the suction and discharge strokes of said pistons relatively to said arcuate inlet and outlet means and thereby to alter the elfective arcuate lengths of said portions, and means to effect said angular adjustment.

5. A fuel pump as claimed in claim 4 in which said means to effect said angular adjustment comprises a first gear Wheel co-ax'ial with and secured for rotation with said cam-plate, and a secondgear wheel engaging said first gear wheel, said second gear wheel being angularly adjustable from outside said casing. V I

6. A fuel pump comprising a generally cylindrical casing having closed ends, a rotor mounted co-axially within said casing with an annular spacebetween said casing and said rotor, the rotor having a plurality of axially-extending bores therein, a piston in eachsaid bore, one end of each said piston extending from the bore in which-it is positioned, the bores having open ports at the ends thereof re-' mote from the pistons and being circumferentially-spaced around the axis of the rotor, a cam-plate inclined to the axis of rotation of the rotor, a spring in each said bore positioned to bias the associated piston into abutment with said cam-plate, stationary structure forming one end, of said casing and having a thrust face co-acting with the end face of the rotor, containing the open ports of the bores, said thrust facecontaining a fuel inlet and a fuel outlet means in the ,form of circumferentially-spaced arcuate apertures co-axial with the rotor, said fuel inlet concentric, arcuate portions of the same radiusbut of 1m equal arcuate length and separated from each other and from said fuel inlet by lands each of arcuate length not greater than the diameter of the ports; a maximum speed centrifugally-operable by-pass valve, carried by said rotor and communicating with-the longer arcuate portion and operable at a predetermined maximum rotational speed of said rotor to by-pass at least part of the delivery from said longer arcuate portion to the interior of said casing, and a minimum speed centrifugally-operable by-pass valve, carried by said rotor and also communicating with the longer arcuate portion and operable at a predetermined rotational speed of said rotor, lower than said maximum speed, to by-pass at least part of the delivery from said longer arcuate portion to the'interior of said casing, a fuel supply pipe connection in said casing, whereby fuel is supplied from outside said casing to the interior thereof, and two separate delivery ducts in said stationary structure, one of said delivery ducts leading to the outside of said casing from each portion of said outlet means, said camplate beingangularly adjustable about the axisof rotation of said rotor, whereby to vary the angular positions of the beginning and end of the suction and discharge strokes of said pistons relatively to said arcuate inlet and outlet means and thereby to alter the eifective arcuate lengths of said inlet and outlet means, and means to effect said angular adjustment. 7

References Cited by the Examiner UNITED STATES PATENTS 1,912,738 6/33 -Svenson 1032 2,117,512; 5/38 Scott 1034l 2,452,470 10/48 Johnson 1 03-2 2,665,637 1/54 Lauck 1O342 2,716,946 9/55 Hardy 103-2 2,749,844 6/56 Weisenbach et al. 103l62 2,820,415 1/58 Born 103-42 2,835,323 5/58 BOOth l0342 2,847,938 8/58 Gondek 103162 2,887,060 5/59 Adams et al. 10342 2,896,546 '7/59 Lundgren et a1. 103-162 2,965,04 2' 12/60 King et a1 103--2 .2,993,445 7/61 Ostwald 1O342 X 3,007,513 11/61 Aspelin 103-42 FOREIGN PATENTS 556,825 5/58 Canada. 1,184,754 2/591. France.- 580,656 8/58 Italy.

LAURENCE V. EFNER, Primary Examiner JOSEPH H. BRANSON, J Examiner.

Claims

1. A FUEL PUMP COMPRISING A GENERALLY CYLINDRICAL CASING HAVING CLOSED ENDS, A ROTOR MOUNTED CO-AXIALLY WITHIN SAID CASING WITH AN ANNULAR SPACE BETWEEN SAID CASING AND SAID ROTOR, THE ROTOR HAVING A PLURALITY OF AXIALLYEXTENDING BORES THEREIN, A PISTON IN EACH SAID BORE, ONE END OF EACH SAID PISTON EXTENDING FROM THE BORE IN WHICH IT IS POSITIONED, THE BORES HAVING OPEN PORTS AT THE ENDS THEREOF REMOTE FROM THE PISTONS AND BEING CIRCUMFERENTIALLY-SPACED AROUND THE AXIS OF THE ROTOR, A CAM-PLATE INCLINED TO THE AXIS OF ROTATION OF THE ROTOR, A SPRING IN EACH SAID BORE POSITIONED TO BIAS THE ASSOCIATED PISTON INTO ABUTMENT WITH SAID CAM-PLATE, STATIONARY STRUCTURE FORMING ONE END OF SAID CASING AND HAVING A THRUST FACE CO-ACTING WITH THE END FACE OF THE ROTOR, CONTAINING THE OPEN PORTS OF THE BORES, SAID THRUST FACE CONTAINING A FUEL INLET AND A FUEL OUTLET MEANS, IN THE FORM OF CIRCUMFERENTIALLY-SPACED ARCUATE APERTURES CO-AXIAL WITH THE ROTOR, SAID FUEL INLET COMMUNICATING WITH THE INTERIOR OF SAID CASING, SAID OUTLET MEANS BEING DIVIDED INTO AT LEAST TWO CIRCUMFERENTIALLY-SPACED, CONCENTRI, ARCUATE PORTIONS OF THE SAME RADIUS, SEPARATED FROM EACH OTHER AND FROM SAID FUEL INLET BY LANDS EACH OF ARCUATE LENGTH NOT GREATER THAN THE DIAMETER OF THE PORTS, AT LEAST ONE CENTRIFUGALLYOPERABLE BY-PASS VALVE, CARRIED BY SAID ROTOR AND COMMUNICATING WITH ONE OF SAID ARCUATE PORTIONS OF SAID OUTLET MEANS AND OPERABLE TO BY-PASS AT LEAST PART OF THE DELIVERY FROM SAID ARCUATE PORTION TO THE INTERIOR OF SAID CASING AT A PREDETERMINED ROTATIONAL SPEED OF SAID ROTOR, A FUEL SUPPLY PIPE CONNECTION IN SAID CASING, WHEREBY FUEL IS SUPPLIED FROM OUTSIDE SAID CASING TO THE INTERIOR THEREOF, AND AT LEAST TWO SEPARATE DELIVERY DUCTS IN SAID STATIONARY STRUCTURE, ONE OF SAID DELIVERY DUCTS LEADING TO THE OUTSIDE OF SAID CASING FROM SAID OUTLET APERTURES RESPECTIVELY.