US3058425A

US3058425A - Liquid fuel pumps for internal combustion engines

Info

Publication number: US3058425A
Application number: US9893A
Authority: US
Inventors: Evans Fraser Mackie
Original assignee: CAV Ltd
Current assignee: CAV Ltd
Priority date: 1960-02-19
Filing date: 1960-02-19
Publication date: 1962-10-16
Anticipated expiration: 1979-10-16

Description

Oct. 16, 1962 F. M. EVANS 3,058,425

. LIQUID FUEL PUMPS FOR INTERNAL COMBUSTION ENGINES Filed Feb. 19, 1960 2 Sheets-Sheet 1 Oct. 16, 1962 F. M. EVANS 3,058,

LIQUID FUEL PUMPS FOR INTERNAL COMBUSTION ENGINES Filed Feb. 19, 1960 2 Sheets-Sheet 2 This invention relates to liquid fuel pumps for internal combustion engines, and of the kind comprising a body part, a rotary distributor in the body part, and an injection pump at one end of the distributor, said injection pump including a head in which is formed a transverse bore containing at least one reciprocable plunger which is movable inwardly as the head rotates by its interaction with a surrounding annular cam, and the distributor having a bore which at one end is in communication with the bore of the injection pump, and Which at its other end is in communication with a passage adapted to register in turn, as the distributor rotates, with each of a plurality of delivery ports in the body part.

The object of the present invention is to incorporate in such a pump a convenient means for varying the quantity of fuel fed to the delivery ports without varying the timing of the commencement of each feeding operation.

According to the invention a pump of the kind specified has in combination an axially movable shuttle accommodated intermediate the ends of the bore in the distributor, passages formed in the distributor and through which fuel can be fed alternately by a feed pump to the ends of the bore in the distributor at opposite sides of the shuttle, annd a throttle for controlling the quantity of fuel fed to said other end of the bore, the arrangement being such that fuel fed to said other end of the bore is discharged to the delivery ports in turn by the movement of the shuttle resulting from the displacement by the injection pump of fuel fed to said one end of the bore, and the instant at which said discharge ceases is determined by a spill passage arranged in the distributor so as to be uncovered by the shuttle at the end of its discharge stroke.

In the accompanying drawings:

FIGURE 1 is a sectional view illustrating one example of the invention,

FIGURES 2, 3 and 4 respectively are sections on the

lines

22, 33 and 44 in FIGURE 1,

FIGURE 5 is a part-sectional view illustrating a further example of the invention, and

FIGURES 6, 7 and 8 respectively are sections on the lines 6-6, 77 and 8--8 in FIGURE 5.

Referring first to FIGURES 14 of the drawings there is provided a body part 11 formed in two portions and which at one end contains a feed pump 12 of the kind comprising a rotary impeller provided with vanes. The pump 12 has an inlet 13 and an outlet 14 formed in the body part 11, the inlet and outlet being interconnected through a spring-loaded relief valve (not shown) which limits the pressure which can be generated by the pump 12.

At the other end of the body part 11 is contained an injection pump which includes a rotary head 15 having formed in it a transverse bore 16. The bore 16 extends diametrically through the head 15 and contains a pair of reciprocable plungers 17. As the head 15 rotates each plunger 17 is movable inwardly at an appropriate timing, by the interaction of a roller 18 at its outer end with a surrounding annular cam 19. Alternatively each plunger 17 may be movable inwardly by the interaction of a cam surface at its outer end with a plurality Patented Oct. 16, 1962 of equi-angularly spaced rollers mounted Within recesses.

in the internal periphery of a surrounding annulus, this annulus together with its rollers being herein referred to as an annular cam. Moreover, the bore 16 may extend only part way through the head 15 and contain a single plunger.

The rotary parts of the feed and injection pumps are interconnected by a cylindrical distributor 20 and are adapted to be driven as a unit by the engine through a shaft 21. In the distributor is formed an axial bore 22 which at one end is in communication with the bore 16 and which at its opposite end is in communication with a radial delivery passage 23 formed in the distributor 20. The passage 23 communicates, as the distributor rotates, with each in turn of a plurality of angularly spaced delivery ports 24 in the body part 1-1, the ports 24 being adapted for connection to the different cylinders of the engine.

In the body part 11 is an annular chamber 25 to which fuel is supplied at a substantially constant pressure from the feed pump 12 through a passage 26 in the body part. Fuel can flow from the chamber 25 through a passage 27 to a supply port 28 in the body part at a rate dependent upon the setting of an angu-, larly or axially adjustable throttle 29 in the body part. As the distributor 20 rotates fuel can flow from the port 28 to each in turn of a plurality of supply passages 30 in the distributor 20, there being as many passages 30 as there are engine cylinders. The passages 30 are radially disposed and equi-angularly spaced, and communicate at their inner ends with the bore 22 of the distributor near the end incorporating the passage 23.

Also leading from the chamber 25 are four equi-angularly spaced filling ports 31 in the body part 11, and for co-operation with the ports 31 there are formed in the distributor 20 a pair of diametrically opposed filling passages 32. Moreover, in the distributor 20 are formed a pair of diametrically opposed spill passages 33 which are angularly spaced from the passages 32 and which termi-- nate at their outer ends in annular groove communicating with the chamber 25 through a port 34. The passages 32 at their inner ends communicate with the bore 22 near the injection pump, and the passages 33 communicate at their inner ends with the bore 22 at a position betweenthe inner ends of the passages 32 and the pasasges 30.

In the bore 22 at a position between the inner ends of the

pasasges

30, 32 is a cylindrical shuttle 35 which is movable axially in the bore 22 in the manner of a piston. Axial movement of the shuttle 35 is limited by any convenient mean ssuch as screw-threaded stops 36 engaged at opposite ends of the bore 22 so that the shuttle 35 can never move into a position to cover either the passages 30 or the pasasges 32.

In order to understand the operation of the pump, let it be assumed that initially the shuttle 35 is in the position illustrated in FIGURES l-4, in which it uncovers the spill passages 33. Whilst the shuttle 35 is in this position one of the passages 30 registers with the port 28 and as a result fuel flows from the chamber 25 to the end of the bore 22 remote from the head 15 at a rate dependent upon the setting of the throttle 29. In consequence the shuttle 35 is moved towards the head 15 by a distance dependent upon the quantity of fuel which has been admitted to the last mentioned end of the bore 22. This movement of the shuttle 35 takes place because any fuel pressure in the end of the bore adjacent the head 15 is reduced due to slight centrifugal outward movement of the plungers 17. Subsequently the pair of passages 32 register with a pair of the ports 31 and fuel is supplied from the chamber 25 to the side of the shuttle 35 nearer the head 15. The effect of this is to move the plungers 17 outwardly to a full extent determined by the plungers 17 are moved inwardly by their interaction.

with the cam 19, thereby causing the shuttle 35 to be moved away from the head 15 to discharge fuel from its side remote from the head to the appropriate engine cylinder until the shuttle 35 uncovers the spill passages 33 and permits escape of the fuel from its side nearer the head 15 to the chamber 25. Thereafter the cycle of action is repeated to feed fuel in turn to each of the engine cylinders.

The modification of the invention illustrated in FIG- URES -8 is similar to the example illustrated in FIG- URES 1-4, and like parts in the several views have been designated with the reference numerals. In the modification, the bore 22 extends transversly within the distributor 20, and communicates with the bore 16 through a groove 41 and a passage 42. The groove 41 replaces the passages 32 in the first example and communicates as the distributor rotates with the filling ports 31. Moreover, in lieu of the port 28 and the passages 30 (FIGURE 3) there are provided four ports 28a (FIGURE 7) which can register with the bore 22 through a single groove 43 which serves in addition to connect the bore 22 to the ports 24 as the distributor rotates. Further, the spill passages 33 are replaced by a single passage 33a which opens into a further bore 44 in the distributor, the bore 44 having extending therefrom a pair of passages 45 terminating in annular groove 46 which is at all times in communication with the chamber 25 through a port 47 and the passage 26.

The operation of the modified construction is similar to that described with reference to the first example. It will be appreciated, however, that the modified pump is shown in a more advanced position in its cycle than that shown in FIGURES 1-4.

It will be understood that, since the injection pumps and the portion of the bore in the distributor at the same side of the shuttle will during each cycle be fully charged with fuel, the timing of the commencement of each injection to the engine will be constant. Further the quantity of fuel fed to the engine will be dependent upon the amount of fuel fed to the opposite side of the shuttle, this quantity being in turn dependent upon the setting of the throttle which can be determined by a governor and/or by manually operable control.

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

A liquid fuel pumping apparatus for an internal combustion engine, comprising in combination a hollow body having a cylindrical inner periphery, and provided with a plurality of fuel delivery ports, a rotary cylindrical distributor mounted within said hollow body in peripheral contact with the cylindrical inner periphery thereof, and provided with a bore, an axially movable shuttle situated the distributor bore at a position intermediate the ends thereof, a feed pump for supplying fuel to said distributor bore, an adjustable throttle carried by said hollow body, an injection pump having a rotary part which is rigidly united with one end of, and rotatable with, said distributor, and which is provided with a transverse bore, at least one reciprocable plunger fitting within, and extending from one end of, said transverse bore, and an annular cam surrounding said rotary part so that, during rotation of said distributor, said plunger is movable inwardly by interaction with said annular cam, one end of said distributor bore being in constant communication with said transverse bore, said distributor being provided with passages at least one of which is in constant communication with the other end of said distributor bore, and is arranged to register in turn with said delivery ports during rotation of said distributor, and at least another of which is in constant communication with the first mentioned end of said distributor bore, said pas sages being formed at least in part by openings in the external periphery of said distributor, said hollow body being provided with an annular chamber surrounding a portion of said distributor, an inlet passage for conducting fuel from said feed pump to said annular chamber, fuel transfer port-s extending between said annular chamber and the portion of said distributor provided with the passage in constant communication with the first mentioned end of said distributor bore, an additional passage having one end communicable with said annular chamber through the medium of said adjustable throttle, and at least one additional fuel transfer port in communication with the other end of said additional passage, and leading to the portion of said distributor provided with the passage in constant communication with the second mentioned end of said distributor bore, said fuel transfer ports and the pasasges in said distributor being arranged so that, during rotation of said distributor, fuel can flow from said annular chamber to the second mentioned end of said distributor bore through said adjustable throttle, said additional passage, and said additional fuel transfer port, and can then flow from said annular chamber to the first mentioned end of said distributor bore through the first mentioned fuel transfer ports, and movements of said shuttle in response to the pressure of fuel displaced in the first mentioned end of said distributor bore by said injection pump can serve to discharge fuel, through one of the passages in said distributor, from the second mentioned end of said distributor bore in turn to said delivery ports which are disposed in angularly spaced relationship about the axis of said distributor, and said distributor being provided with at least one spill port adapted to be uncovered by said shuttle for relieving the fuel pressure in the first mentioned end of said distributor bore, and thereby limiting the discharge movements of said shuttle.

References Cited in the file of this patent UNITED STATES PATENTS 2,698,580 Evans Jan. 4, 1955 2,872,912 Braun Feb. 10, 1959 2,883,934 Roosa Apr. 28, 1959 2,913,986 Skipper Nov. 24, 1959 2,922,371 Bischoif Jan. 29, 1960 FOREIGN PATENTS 151,565 Australia Dec. 13, 1951 653,030 Great Britain May 9, 1951