US3194225A

US3194225A - Liquid fuel injection pumps for internal combustion engines

Info

Publication number: US3194225A
Application number: US368593A
Authority: US
Inventors: Kemp Kenneth Albert Walters
Original assignee: CAV Ltd
Current assignee: CAV Ltd
Priority date: 1963-05-24
Filing date: 1964-05-19
Publication date: 1965-07-13
Anticipated expiration: 1982-07-13
Also published as: GB1012857A

Description

United States Patent 3,194,224 AIR COOLED INTERNAL CGMBUSTION ENGINE Leo J. Leclitenberg, Elm Grove, Robert K. Catterson, Brookfield, and Joseph V. Reichenbach, Milwaukee, Wis., assignors to Briggs & Stratton Corporation, Milwaukee, Wis., a corporation of Delaware Original application June 27, 1962, Ser. No. 205,658, now Patent No. 3,118,433, dated Jan. 21, 1964. Divided and this application Oct. 3, 1963, Ser. No. 313,546

(Ilairns. (Cl. 123-119) This invention, like that of the application of Leo J. Lechtenberg, Serial No; 205,658, now Patent No. 3,118,433, of which this is a division, relates to internal combustion engines and refers more particularly to single cylinder air-cooled engines of the type widely used on power lawn mowers.

The object of this invention is to provide a simplified and more practical carburetor for engines of the type indicated, particularly from the standpoint of assuring continued freedom of adjustment of its throttle valve and choke valve, even in dusty and sandy surroundings.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims.

The accompanying drawings illustrate one complete example of the physical embodiment of the invention, constructed according to the best mode so far devised for the practical application of the principles thereof, and in which:

FIGURE 1 is a vertical sectional view through an engine equipped with the carburetor of this invention;

FIGURE 2 is a separated perspective view of the carburetor, a portion of the fuel tank on which it is mounted, and the air cleaner;

FIGURE 3 is a perspective view of the assembled carburetor, but with the air cleaner omitted;

FIGURE 4 is a fragmentary perspective view illustrating a detail of the ignition grounding switch of the engine, with the various parts shown separated fromone another; and

FIGURE 5 is a top view of the carburetor and adjacent structure, but with the air cleaner removed.

Referring now particularly to the accompanying drawings, the numeral 5 indicates generally the main body of the engine which preferably is a die casting such as that of the Lechtenberg Patent No. 2,693,789. Hence, the main body casting forms all but one of the walls of the crankcase and also the finned cylinder 6. The open side of the crankcase, in the vertical shaft engine shown in FIG- URE l, is closed by a cover casting 7 which has the mounting flange 8 of the engine formed thereon and which also provides an oil sump for the crankcase and contains the lower crankshaft bearing (not shown). This lower bearing and another upper bearing also not shown, in the top wall of the crankcase, rotatably mount the crankshaft 9 of the engine, one end portion of which projects downwardly beyond the mounting flange to have the cutter blade of a mower or other instrumentality to be driven secured thereto.

The outer end of the cylinder 6 is, of course, closed by a cylinder head (not shown) which is secured in place by bolts or capscrews 10. As is customary, both the cylinder and the cylinder head have heat dissipating fins thereon.

The upper end of the crankshaft has a flywheel 11 fixed thereto which also serves as the rotor of the engine magneto, indicated generally by the numeral 12. Air

propelling blades 13 on the upper face of the flywheel provide an air impeller or blower capable of delivering a substantial flow of cooling air for the engine. Duct means indicated generally by the numeral 14 directs the cooling air transversely across the finned cylinder 6 and cylinder head.

A rewind-type rope starter indicated generally by the numeral 15 is mounted on the shroud and connected in the customary manner with the upper end of the crankshaft to provide means for starting the engine.

The engine is of the L-head type and, hence, has intake and

exhaust ports

16 and 17 in its cylinder casting. These ports are spaced apart lengthwise of the crankshaft axis with the intake port 16 nearest the air impeller or blower. As is customary, the ports open to valve seats 18 and 19 in the top or outer face of the cylinder casting, and with which the

intake valves

20 and 21 coact in the customary manner.

It is significant to note that the intake port 16 opens toward that side of the cylinder which faces the impeller or blower, i.e. upwardly in the case of the vertical shaft engine shown in FIGURE 1; and that the exhaust port 17 opens laterally or horizontally away from the cylinder.

A muffler 22 is bolted to the cylinder casting over the mouth of the exhaust port 17. This muffler is of novel construction and forms the subject matter of a copending application, Serial No. 233,005, filed October 25, 1962.

At the side of the cylinder opposite that at which the intake and exhaust ports'are located, is a fuel tank 23 and the improved carburetor of this invention, indicated generally by the numeral 24. The fuel tank 23 has a generally oblong or rectangular shape and is mounted directly alongside the cylinder crankcase casting with its top wall 25 substantially in line with the upper side of the cylinderor, more specifically, the cooling fins on the cylinder, as clearly seen in FIGURE 1.

The tank 23 is secured in position by means of suitable mounting brackets, spot welded to the opposite ends of the tank, and bolted to the crankcase cylinder casting.

Since the mounting brackets are spot welded to the opposite ends of the fuel tank, the points of securement of the tank to the engine are relatively Widely spaced, and

being as firmly anchored as they are, it follows that there is no likelihood whatsoever that the fuel tank will work loose as a result of engine vibration. Also, since the carburetor 24 is mounted upon the top wall 25 of the fuel tank by means of a relatively large flange 26, the bottom face of which seats squarely upon the top wall 25 of the tank, utmost assurance is had against loosening of the carburetor. The flange 26 may be secured to the top wall of the tank in any suitable way, as by cap screws 27.

The carburetor is of the type disclosed in the Brown et val. Patent No. 2,529,242. Hence, it has a die cast tubular body 28 which provides a mixture passage 29 in which the fuel and air is admixed and from which the fuel-air mixture issues for delivery to the intake port, and has the flange 26 formed integrally therewith. The fuel is drawn into the mixture passage 29 by engine suction through .a'suction tube 36 which projects per-pendicularly from the bottom of the carburetor mounting flange 26 into a cup or reservoir 31in the upper portion of the fuel tank. The fuel delivered by the suction tube 3% enters the mixture passage of the carburetor through jets (not shown) under the control of a needle valve 32 in the customary manner.

The cup or reservoir is kept filled with fuel from the fuel tank by an engine-suction actuated diaphragm pump 33, which is mounted on the side of a carburetor body opposite its needle valve, and the inlet of which has a suction feed tube 34 connected thereto to project down y 195.5 K. A. w. KEMP 3,

E MP3 FOR INTERNAL COMBUSTI N fig 4. 10

July 13, 1965 K. A. w. KEMP 3,194,225

LIQUID FUEL INJECTION PUMPS FOR INTERNAL COMBUSTION ENGINES Filed May 19, 1964 4 3 Sheets-Sheet 5 17 jig Z5 21 E 19 1% a Q 2? 45 I 44 59 s I Z 4 United States Patent 3,194,225 LIQUID FUEL INJECTION PUMPS FOR INTERNAL COMBUSTION ENGINES Kenneth Albert Walters Kemp, Ealing, Middlesex, England, assignor to C.A.V. Limited, London, Engiand Filed May 19, 1964, Ser. No. 368,593 Claims priority, application Great Britain, May 24, 1963,

, 20,770/63 4 Claims. (Cl. na -139 This invention relates to liquid fuel injection pumps for supplying fuel to internal combustion engines and of the kind comprising a plunger mounted for reciprocation within a bore, actuating means for moving the plunger towards one end of said bore in time relationship with the engine with which the pump is associated to discharge fuel from said one end of the bore to an engine cylinder, an axially movable shuttle mounted within a cylinder, a distributor member arranged to be moved in synchronism with the engine, ports in the distributor member for directing fuel from a source of fuel, at a pressure dependent on the speed of the engine, alternately to opposite ends of said cylinder to move the the shuttle axially in opposite directions, further ports in the distributor member whereby the fuel displaced by the shuttle from one end of the cylinder will be fed to said one end of the bore to move the plunger axially, and a throttle arranged to control the quantity of fuel delivered from said source to the cylinder.

The object of this invention is to provide such a pump in an improved form.

According to the invention in a pump of the kind specified the movement of the shuttle towards the other end of the cylinder is limited by a movable stop member which is arranged to-be moved in accordance with the pressure of fuel delivered from said source, the arrangement being such that, as the speed of the engine changes the stop member will be moved to vary the permitted stroke of the shuttle thereby varying the maximum amount of fuel which can be delivered by the pump to the engine.

In the accompanying drawings:

FIGURE 1 is a sectional side elevation of one example of a liquid fuel injection pump in accordance with the invention,

FIGURE 2 is a sectional view taken on the line 22 of FIGURE 1,

FIGURE 3 is a sectional view taken on the line 33 of FIGURE 1,

FIGURE 4 is a sectional view taken on the line 4-4 of FIGURE 1,

FIGURE 5 is a sectional View taken on the line 5-5 URE 2, and

FIGURE 7 is a view similar to FIGURE 1 with parts of the pump omitted and taken on the line 7-7 of FIG- URE 2.

Referring to the drawings, there is provided a body part 10 in which is mounted a rotary distributor 11 adapted to be rotated in timed relationship with the engine with which the pump is associated. Mounted on one end of the distributor 11 is a feed pump 12 having a fuel inlet 13 and a fuel outlet 14 in the body part these being interconnected by a relief valve, 15 which controls the outlet pressure of the feed pump in a manner such that the pressure is dependent upon the speed of the engine. The inlet 13 is arranged in use to be connected by way of a passage 13a to a source of fuel (not shown).

At the other end of the distributor 11 is a rotary head 16 in which is formed a transverse bore 17 containing a pair of plungers 18 which are arranged to be moved inwardly, as the head rotates, by a pair of rollers 19 respectively which co-act with a surrounding annular cam 20 mounted for limited angular movement within the body part iii. Within the distributor is a longitudinal passage 21 which at one end is in communication with the bore 17 in the head and which at another point is in communication with a radial delivery passage 22 which is arranged to communicate in turn, as the distributor rotates, with a plurality of equi-angularly delivery ports 23 formed in the body part and in communication with the cylinder of the engine respectively. At another point the longitudinal passage is in communication with the inner ends of a plurality of equi-angularly spacedradial inlet passages 24, equal in number to the number of delivery ports 23. Also formed in the body part are a pair of

cylinders

25, 26 which contain a pair of reciprocable and close

fitting shuttles

27, 28 respectively. The cylinder (hereinafter termed the main cylinder) is of larger diameter than the other and the cylinders have their inner ends terminating in a pair of

ports

29, 30 respectively which are arranged to be placed in communication with the longitudinal passage 21, at the same time, by way of a pair of said inlet passages 24 respectively.

In the periphery of the distributor, intermediate the inlet passages respectively, is formed a plurality of longitudinal grooves 31. These grooves are in communication with a circumferential groove 32 in the distributor which is supplied with fuel from the outlet 14 of the pump by way of an adjustable throttle valve 33 mounted in the body part. Moreover the grooves are arranged to communicate with the

ports

29, 30 during at least part of the time when the inlet passages 24 are notin communication therewith.

Also formed in the body part is a series of first transfer passages 34 which are in direct communication with the outer end of the main cylinder 25 and which are arranged to communicate with the grooves 31 during the time when the inlet passages 24 are in communication with the

ports

29, 30. A series of second transfer passages 35 is provided in the body part which are arranged to communicate by way of a plurality of equi-angularly spaced further grooves 36 in the periphery of the distributor 11 with ports 37 in communication with the inlet 13 of the feed pump 12.

The permitted outward movement of the shuttle 27 is limited by an adjustable stop 38 which is normally fixed once the pump has been adjusted, whilst the permitted outward movement of the shuttle 28 is controlled by a stop which is movable in accordance with the outlet pressure of the feed pump. This stop comprises a spring loaded cylinder member 39 which is mounted within 2 a cylinder 44) having one end in communication with the feed pump outlet 14 and the other end, which contains the spring 41 of the member, in communication with the feed pump inlet 13 by way of a passage not shown. The portion of the member 39 presented to the shuttle 28 is profiled to a convenient form as shown in the drawing so that as the fuel pressure applied to said one end of the member 39 increases the permitted outward movement of the shuttle 28 will be reduced. The outer end of the cylinder 26 is arranged to be in communication with the outer end of the cylinder 25 by way of a port 42 and a passage 42a in the wall of the cylinder containing the member and the arrangement is such that when the outlet pressure of the feed pump is sufficient to move the member against its spring this port will be uncovered by the member to place the outer ends of the

cylinders

25, 26 in communication with each other. Moreover a transfer port 25a is provided in communication with the outer end of the cylinder 26 and this is arranged to communicate with the inlet of the feed pump, by way of a groove 36 V and a port 'at the same communicate with the inlet of the feed pump,

The operation of thepump will now be described, as; suming that theengine with which the pump is associated.

has been started. During rotationof the distributor 11 the plungers. 18 a're'moved inwardly by their interaction with the annular cam 20 and fuelis displaced fromthe bore '17 along the longitudinal passage 21 and the delivery,

passage 22toone of the delivery ports 23v and to an'engine cylinder. At the same time fuel from the feed pump passes by way of the throttle valve 33, the circumferential groove 32 and a pair of. the longitudinal; grooves 31 to the 25,? 2 6 to move the shuttle's inwardly. At the same time fuel will be displaced from the inner ends of the, cylinders and vWill flow via the ports 29, '30 a pair of inlet passages 24 and the longitudinal passage 21 to the bore 17 to move the plungers-18 outwardly. This cycle is repeated as the distributor in turn.

. When theuengine is' atirest the outlet pressure of the feed pump Willbe Zero and the spring loaded cylindrical member 39 will have been movedby its springlto a position in which the port 42 in the wall of the vcylinder containing the member will be closed. During the first few quently'fuel from the feed pumpisfed directly to'the' bore in the head during the filling periods thereof and an.

excess quantity of fuel above the normal maximumuuantity of fuel willbe fed to, the engine. As soon, as the 'speedof the engine increases the pressure offuel deliv.. ered from the feed pump will rise-and the cylindrical member39- willibe moved againstitsspring to openport42 and to place the outer end.

ofthe cylinders

25, 26 in coma The movement of the mernber 39 will'cause the shuttle to be moved inwardly and munication with each other.

the port 44a will be closed to reduce the quantity of fuel fed to the engine. Moreover as previously stated, as the speed of-theengine and pump increases then'the permitted outward movement f the shuttle 28 will be reduced and hence the maximum quantity of fuel which may be delivered to the engine will be reduced. a The annular cam is permitted limited angularmovement to vary the timing of the'injection of fuelinto the engine and for thispurpose there is provided-,in the body part, a cylinder 44 .which containsa spring loaded piston; 45 which is arranged to be subjected to the outlet pressure of the feed pumplZ during the time' when the plungers are. being moved outwardly by the flow of fuel into the.

bore. This. is achieved by arranging that eachof the longitudinal grooves 36, in turn,.bridges a pairot. ports, 46, 47 in the body part, port 47 being connected to the 7 cylinder; 44 by way of a circumferential groove 48 and passage 49 and the port 46 to the outlet of the feed pump.

The pressure of fuel upstream of the'throttle 33 is de-' pendent ;uponthe speed of the engine,-as previously stated, and alsozupon the setting of the throttle which is dependent upon the load on'the engine v The effect due to the latter is increased further by the provision of a restricted orifice rotates and fuel is fed to each engine cylinder time as the transfer ports 35 inner ends of the

cylinders

25, 26 to move the shuttles ou'twardly and fuel is displaced from the outer-. ends of the cylinders through transfer passages 35, grooves 36 to revolutions ofthe engine the shuttle 28 will be moved I outwardly to its maximum extentas permitted by an excess fuel recess 43provided in the cylindrical member and r in this position an excess fuel port 44a in the .wall of the cylinder 26 is uncovered. This port is in open communh' 1 cation with the circumferential groove 32 and consey 48in the outletlof-the feed' pumpffwhich creates a presi 'sure drop dependent upon the quantity ,of fuel being delivered by the pump.v

Having thusdescribed my invention what Iolaim as new 4 and .desireto secure by'Letters Patent'is: 1; Liquid: fuel pumping apparatus, for supplying 'fuel "to an internal combustionengineandcomprisingyan 'injection pump arrange d to be driven i n;tin;'1ed relationship I with theienginqsaid injection .pump beingiarranged'dur- I .-ing a pumping stroke to deliver f u'e l to the engine, a'feed pump for providing fu'elunder pressurg valve nieansifo'r' 1 controlling the output pressure of ,'sa idj. feed-;pump" inla; manner which .varie s as the speed ofithe engine, an axially movable; shuttle contained within acylinder, a distributor member arranged to' be i driven :in i sync hronism with the r injection pump, passagesjin the jzli stribut'or forf'dir'ecting' fuel'from said feed pump-to opposite ends of: said cylin derin turn, thereby causingsaidshuttle to:be moved axial ly therein, further passages in thedistributorarranged so 7 that fuel displaced frombne end of, said cylinder-will.

passto the injectionpuinp during a if llingtst roke thereof, Vj an axially movable stop for limitingjthemovement of said shuttle away from' said'one end of the cylinder, thezface I of-said stop against which the shuttle bears .being inclined' 7 so that as thestop isi'mo'ved axially the; amount by which a the shuttle, can move away from; said one end of the cylin der will be;varied,,a condnitlthrough which one end ofthe .7 stop is exposed to the output pressure of the feedpump whereby the axial position Lot-the stop .willbe, dependent upon the output pressure; ofisaid f eed .pumpirand resilient means for opposingthe movement of said stop-by the pre's sure of fuel, whereby as tiles-pressure of fuel delivered by;

said feed pump varies 5011116 permitted excursionZof the shuttle will be variedzto vary the amount of fuelwhich' can be delivered to the engine;

zfLiquid fuel u i gapp r turqr uri iy i m an internal combustion engine'a nd comprising, aninjecs tion pump arranged tohe driven intimed'relationship with1 the .engine,said injection pump being arranged duringa pumping stroketo deliver fuelato'theengine, ;a'-feed-pump for providing fuel; under 5 pressure, valve means for con-j trolling the output pressure'offsaid feed pump in 'a'mane ner which varies as the :speed'-.,of the engine, an axially; i movable shuttle contained within aicylinder, {a distributor 1 member arranged to be: driven in synchrfonism with the injection z'pump, passages .in V the distributor for directing i a fuel fromsaid feed pump toopposite 'endso'f saidcylinden in turn,-thereby causing said shuttle to be moved axially therein, further-passages inthedistribntor'arranged so that fuehdisplaced from "oneend ,of the cylinder: willapass to, V

the injection} pump duringafilling stroke. thereof, anaxial-i 1y, movable stop for limiting the movement ofsaid shuttle away from, said one end of the cylindenithe-face of said;

stop against which the shuttle bears beingiuclined so that as the stop is moved axially. the amount I bygwhich the: shuttle can move away tromsaid one end, dfithecylinde'r;

will be varied, agconduitthroughwhich one endfof the:

' stop is exposed to the output pressure of the f eed-pump. whereby the; axial position of thejstop will bexdependent 1 uponthe outputipressure of saidifeed pump and-resilient, means for opposing the; movement of said stop by the pressure-of ,fuel, wherebyasthe pressure of fuel delivered by said feed pump varies .350 the permitted excursion of; the shuttle will bevaried to; vary the amount of fuelwhich f can be delivered to the engine, airecess formed in .said. face'of said stop said recess bein'grpositioned 'so that, when the fuel pressure delivered by said feed pump is below a r predetermined .value,lthe shuttle, can 7 enter said recess, a

port in the wall of said cylinder, said port beingarranged] 'to be uncovered by said shuttle when the latterenters said;

, recess; a 'further,conduitithrough which the port'is in:

communication awith' theoutlet of;the feed pump so that during the filling stroke of the injection pump fuel willbei' fed directly thereto, and valve means operableibysaidf cylinder whilst the pressure of fuel delivered by said feed pump is below the predetermined value.

3. Liquid fuel pumping apparatus for supplying fuel to an internal combustion engine and comprising, an injection pump arranged to be driven in timed relationship with the engine, said injection pump being arranged during a pumping stroke to deliver fuel to the engine, a feed pump for providing fuel under pressure, valve means for controlling the output pressure of said feed pump in a manner which varies at the speed of the engine, a pair of axially movable shuttles contained within a pair of cylinders respectively, a distributor member arranged to be driven in synchronism with the injection pump, passages in the distributor for directing fuel from said feed pump to opposite ends of said cylinders in turn thereby causing said shuttles to be moved axially therein, an adjustable throttle member for controlling the quantity of fuel supplied to said cylinders from said feed pump, further passages in the distributor arranged so that fuel displaced from one end of said cylinders will pass to the injection pump during a filling stroke thereof, an axially movable stop for limiting the movement of one of said shuttles away from said one end of its cylinder, the face of said stop against which the shuttle bears being inclined so that as the stop is moved axially the amount by which the shuttle can move away from said one end of the cylinder will be varied, a conduit through which one end of the stop is exposed to the output pressure of the feed pump whereby the axial position of the stop will be dependent upon the output pressure of said feed pump, and resilient means for opposing the movement of said stop by the pressure of fuel, whereby as the pressure of fuel delivered by said feed pump therein so the permitted excursion of the shuttle is varied to vary the amount of fuel which can be delivered to the engine, a recess formed in said face of said stop, said recess being positioned so that, when the fuel pressure delivered by said feed pump is below a predetermined value, the shuttle can enter said recess, a port in the wall of said cylinder arranged to be uncovered by said shuttle when the latter enters said recess, a further conduit through which the port is in communication with the outlet of the feed pump through said throttle member so that during the filling stroke of the injection pump fuel will be fed directly thereto, and valve means operable by said stop to prevent the flow of fuel to the other end of the cylinder whilst the pressure of fuel is below said predetermined value.

4-. A pump as claimed in claim 3 including a pressure operable piston contained within a cylinder for determining the timing of injection of fuel to the engine by said injection pump, a restriction intermediate the outlet of said feed pump and said throttle member, a conduit interconnecting one end of said cylinder containing the fluid pressure operable piston and a point intermediate said restriction and said throttle member and valve means constituted by said distributor whereby communication between said point and said one end of the cylinder is established only during the filling strokes of the injection pump.

References Cited by the Examiner UNITED STATES PATENTS 3,025,797 3/62 Hutcheon l23139 10/63 Kemp l23139

Claims

1. LIQUID FUEL PUMPING APPARATUS FOR SUPPLYING FUEL TO AN INTERNAL COMBUSTION ENGINE AND COMPRISING, AN INJECTION PUMP ARRANGED TO BE DRIVEN IN TIMED RELATIONSHIP WITH THE ENGINE, SAID INJECTION PUMP BEING ARRANGED DURING A PUMPING STROKE TO DELIVER FUEL TO THE ENGINE, A FEED PUMP FOR PROVIDING FUEL UNDER PRESSURE, VALVE MEANS FOR CONTROLLING THE OUTPUT PRESSURE OF SAID FEED PUMP IN A MANNER WHICH VARIES AS THE SPEED OF THE ENGINE, AN AXIALLY MOVABLE SHUTTLE CONTAINED WITHIN A CYLINDER, A DISTRIBUTOR MEMBER ARRANGED TO BE DRIVEN IN SYNCHRONISM WITH THE INJECTION PUMP, PASSAGES IN THE DISTRIBUTOR FOR DIRECTING FUEL FROM SAID FEED PUMP TO OPPOSITE ENDS OF SAID CYLINDER IN TURN, THEREBY CAUSING SAID SHUTTLE TO BE MOVED AXIALLY THEREIN, FURTHER PASSAGES IN THE DISTRIBUTOR ARRANGED SO THAT FUEL DISPLACED FROM ONE END OF SAID CYLINDER WILL PASS TO THE INJECTION PUMP DURING A FILLING STROKE THEREOF, AN AXIALLY MOVABLE STOP FOR LIMITING THE MOVEMENT OF SAID SHUTTLE AWAY FROM SAID ONE END OF THE CYLINDER, THE FACE OF SAOD STOP AGAINST WHICH THE SHUTTLE BEARS BEING INCLINED SO THAT THE STOP IS MOVED AXIALLY THE AMOUNT BY WHICH THE SHUTTLE CAN MOVE AWAY FROM SAID ONE END OF THE CYLINDER WILL BE VARIED, A CONDUIT THROUGH WHICH ONE END OF THE STOP IS EXPOSED TO THE OUTPUT PRESSURE OF THE FEED PUMP WHEREBY THE AXIAL POSITION OF THE STOP WILL BE DEPENDENT UPON THE OUTPUT PRESSURE OF SAID FEED PUMP AND RESILIENT MEANS FOR OPPOSING THE MOVEMENT OF SAID STOP BY THE PRESSURE OF FUEL, WHEREBY AS THE PRESSURE OF FUEL DELIVERED BY SAID FEED PUMP VARIES SO THE PERMITTED EXCURSION OF THE SHUTTLE WILL BE VARIED TO VARY THE AMOUNT OF FUEL WHICH CAN BE DELIVERED TO THE ENGINE.