US2818848A

US2818848A - Fuel injection pumps

Info

Publication number: US2818848A
Application number: US494502A
Authority: US
Inventors: Friedlander William
Original assignee: Mono Cam Ltd
Current assignee: Mono Cam Ltd
Priority date: 1954-03-17
Filing date: 1955-03-15
Publication date: 1958-01-07
Anticipated expiration: 1975-01-07

Description

Jan. 7, 1958 v w. FRIEDLANDER4 FUEL I NJECTfON PUMPS 3 Sheets-Sheet 1 Filed Ma rch 15, 1955 Jan. 7, 1958 w. FRIEDLANDER FUEL INJECTION PUMPS 3 Sheets-Sheet 2 Filed Mar ch 15, 1955 IQ MHGLEECM W. FRIEDLANDER FUEL INJECTION PUMPS s sheets-sheet 3 Filed March 15, 1955 United States Patent-O FUEL INJECTION PUMPS Esher, England,

hl Wood William Friedlander, Hmc ey England a assignor to Mono-Cam Limited, London, company of Great Britain This invention relates to fuel injecting pumps for internal combustion engines, particularly, though not exclusively, compression-ignition engines. It 18 concerned i h improvements in pumps of the kmdtheremafter referred to as the kind specified) compr sing one or more piston and cylinder pumping assemblies 1n which the effective length of the delivery stroke of the or each piston is controlled by actuation of a single regulating member which adjusts for the or each cylinder the position of an element which determines at what point of the delivery stroke fuel will be spilled from the cylinder into a chamber from which a passage leads to the inlet side of the pump, the fuel tank or a like low-pressure region, constricting means being provided for restrictlng the flow of fuel through the passage leading from the chamber receiving the spilled fuel to the low-pressure region so that the pressure prevailing in the chamber will be a function of the speed and loading of the engine supplied by the pump, a control spring being provided to urge the regulating member towards the position corresponding to maximum delivery of the pump, and pressure-responsive means exposed to the pressure prevailing within the chamber being arranged automatically to actuate the regulating member to vary the delivery of the pump in the sense for opposing variations of the speed of the engine from that value corresponding to the setting of the pump.

The object of the present invention is to provide an improved automatic delivery-controlling device for a pump of the kind specified which shall be sensitive, and efi'icient over a relatively wide range of speeds and which is of relatively simple construction.

According to the present invention, in a pump of the kind specified, the setting of the pump for a given engine speed is controlled by the loading of the control spring and by the restricting effect of the constriction and means is provided whereby at least the setting of the pump for low engine speeds is varied in the sense to increase the engine speed by simultaneously increasing said loading and reducing said restricting effect and in the sense to reduce the engine speed by simultaneously reducing said loading and increasing said restricting effect. Thus at low engine speeds, e. g. idling speeds, the loading of the control spring is at a minimum and the restricting effect of the constriction is at a maximum and the self-governing action of the pump is achieved with a minimum amount of spill.

Advantageously, automatic actuation of the regulating member in the sense for increasing the delivery of the pump is arranged to produce simultaneously an increase in said restricting effect and a reduction in said loading and vice versa. This increases the stability of the selfgoverning action of the pump.

In one construction, the common regulating member extends within the spill chamber and is connected to a fixed abutment arranged within this chamber by the pressure responsive means which includes a flexible wall 2,818,848 Patented Jan. 7, 1958 exposed on one face to the pressure prevailing in the spill chamber and on the other face to the pressure prevailing in the low pressure region of the pu p and the constricting means comprises a passage extending through the common regulating member and the flexible wall and a restrictor pin which extends into said passage to reduce the effective cross-sectional area thereof. The control spring is arranged between the regulating member and the restrictor pin in such manner that movement of the one relative to the other will simultaneously vary the loading on the control spring and the restricting effect of the constricting means.

In an alternative construction the common regulating member extends within the spill chamber and is formed with a spigot part which extends as a close sliding fit within a sleeve communicating at one end with the low pres sure region of the pump and at the other end with the spill chamber so that the regulating member is subjected to both the pressure prevailing in the spill chamber and the pressure prevailing in the low pressure region and is responsive to the difference of these two pressures, and the constricting means comprises a passage extending through the common regulating member and the spigot part and a restrictor pin which extends into said passage to reduce the effective cross-sectional area thereof.

In order that the invention may be more clearly understood, one form thereof will now be described by way of example, reference being made to the accompanying drawings in which:

Figure 1 is a section taken on the line II of Figure 2;

Figure 2 is an end elevation of the feed pump shown in Figure I seen in the direction of the arrow A of that figure,

Figure 3 is a fragmentary section view illustrating a modification,

Figure 4 is a fragmentary sectional view of the pump shown in Figure 1 illustrating a modification, and

Figure 5 is a view similar to Fig. 3 illustrating a further modification.

The pump comprises a generally cylindrical housing 1 having a cam chamber 2 at one end, a spill chamber 3 intermediate its length and a series of delivery connections 4 at its other end which are each connected to the fuel injection device of the respective engine cylinder. At this end of the housing there are appropriate pump cylinders 5 disposed around and parallel with the axis of the housing and each communicating through a delivery valve 6 with the corresponding delivery connection 4. The cylinders 5 and the respective pistons or plungers 7 are all identical and only one set of these parts need be described here. The cylinder wall is formed with radial bores 8 near its outer end and is surrounded at this location by an annular fuel supply passage 9. This is in permanent communication with a central annular chamber 10 formed by a recess in the cylindrical wall of the enlarged inner end 11 of an axial bore 11a in the housing 1 provided to admit the passage of a stem 12 attached to a common regulating member 13 located in the spill chamber 3. The common regulating member 13 is of dlsc form and a ring 14 is secured to that face thereof remote from that attached to the stem 12 by bolts 15 which extend through the ring 14 and engage in threaded bores 16 in the regulating member 13. The common regulating member and the ring 14 serve to position controlling sleeves 17 which are a close sliding fit on the pistons 7 working in the cylinders 5. Each piston 7 is a close sliding fit in its cylinder 5 which projects, with play, part-way into an aperture 18 in the regulating member 13, the corresponding controlling sleeve 17 being mounted on the latter in such manner that it may move laterally ('e. g. radially or circumferentially of the member) without being capablegof any appreciable motion relative to the member in the axial direction. Axial ad ustment of the regulating member 13 varies the positron of the controlling sleeves: 17 relative to the length of the plstons 7 which are formedtwith axial bores 7a leading from their operativeiend faces to radial-bores 7b the opening of which occurs as theyv move out of the controlling sleeves 17 during the delivery strokes of the respective pistons.

The piston 7 continues beyond the sleeve 17; through an oversize hole-19 in a partition member or fixed abutment 20 secured transversely of the' spillchamber 3 and through a flexible packing Washer-121 which is a close fit on the piston 7 and is surroundedb'ya compression spring 22 bearing at its one end uponthe washer 21 to urge the latter into oil-tight engagement with the marginal edge of the abutment 20*around the'hole 19 and at its other end uponacollar; 23:;securedfonfthe end of the piston 7. The packing Washer 21 ens'uresithat the chamber 3 on one side of the partition or abutm'ent 20 is isolated from the compartment 2aron the other'side' thereof, the compartment 2a 'being in free 'communication with the cam chamber) by way of a? passage 24. The 'end of the piston 7 to which the collar'23 is secured bears upon a sliding member 25 which carries rollers 26 for contacting the operative camface 27a of the cam 27 rotatable within the cam chamber 2 by means of a shaft 28 extending axially throughthe end of the housing 1 to be driven from the engine crank-shaft at an approprlate speed. The sliding-members 25 for actuating the pistons 7 are mounted in guides 29 in a portion of the housing 1 which latter is formed centrally with a pump cylinder 30 having its axis coincident with that of the housing and having an open end directed towards the cam 27. A passage 31 extends from adjacent the closed end of the pump cylinder 30 to a valve housing 32 secured to the pump housing 1. An inlet133; tothe valve housing 32 is adapted to connect the latter to the fuel supply or low-pressure region to .supplytuel to'the cylinder 30 by way of a non-return-valve; 34;; ---The 'valve housing 32 also contains, a cylinder'35connected byway of

passages

36 and 37 to the inlet 33 and a piston 38 arranged Within the cylinder .35 as--a closesliding fit 'andzoperable from theexterior ofthe valve housing 32 by means of a priming handle 39to pump fuelfrom the fuel supply; The

passage 36 and the cam charnher= 2are b'othwonnectedko a non-return valve l00 leadingltoianroutlet 101-this last mentioned outlet l0l -;,being connected" through 9 a filter 10.2 to .an inlet 103""leadin'g to theanniflai-"ehamber '10. Wnhm the cylinder 30iis' slidably'arranged a hollow piston 40 which opensin th'edire'ction towards the cam 27. A piston rod 41 is-arranged to operate'the piston 40 and is itself operable by an extension 42 of a pin 43 which acts as a support for the. cam-engaging roller 26 of one of the sliding members 25. 'A longitudi nal slot 44 is formed through the wall of the cylinder 30 and the extension 42 of the pin 43 extendslthrough-this slot 44 to be secured in a transverse .bore'in the piston rod by means of a grub screw 45. '1 The piston rod 41 is formed with a head 46 arranged to engage the "closed end of the piston 40 and is surrounded-by a co'iled spring'47 which bears at'one'end against the' head- 46jaridatthe other against an inturned lip 49 'for rne d the piston 40 to urge the clo'sd efn gagement with the head 46"of lthe'p1s to n;rod 41.; The cylinder 30," piston 40 and valve P IQ d an assembly for pumping merfr'enithe supply'to the'purnp which is similar to that described 'inmy'iU 3. Patent No. 2,672,817. 1 w f The'partition member 20" i's formed centrally with an end against a-washer 48 w-hich is firgedfby the'spring axially extending cylindrical 'wall 50' surrounding a liner 51 within which slides a spigot part 52 secured to the regulating member 13. The spigot part 52 is formed with an axiallborejtwhich QQMQQiQMQiMLiIlfiQSLQlI: tially radial bores 54 formed in the spigot part 52.

The spigot part 52 extends through the centre of an annular flexible diagram 55 which is secured at its inner edge to the spigot part. 52vadjacent the regulating member 13 in a fluid tight manner and the diaphragm 55 is similarly secured at its outer periphery to an annular collar 56 which closely surrounds the cylindrical wall 50. This provides a chamber 57 which is in constant communication with the chamber 2a by way of the bores 53 and 54 in the spigot part 52. The enlarged inner end 11 of the bore 11a in the housing 1 has tightly fitted therein a sleeve 58 through which the stem 12 of the regulating member 13 extends as a close sliding fit and the outer cylindrical surface of whichforms the inner wall of the central annular chamber 10. The stem 12 is formed with a co-axial bore 59 therethrough, this bore communicating withv'a' co-axial passage 60 extending through the regulating member to communicate with the axial bore 53 through the spigot partSZ. The diameter of the bore 59 is reduced intermediate its length to form a shoulder 61 and the stem 12 is formed adjacent the junction of the bore 59 and passage 60 with a pair of radial bores 62 which place the passage 60 in communication with the spill chamber 3.

In order that the regulating member 13 may be adjusted by hand or other means, the stem 12 is extended by an extension sleeve 63 which is threaded on its outer surface and is screwed into the open end of the stem 12 remote from the regulating member 13 and extends outside the housing 1. A nut 64 is screwed on to the outer end of the extension sleeve 63 and the latter is surrounded by a compression spring 65 which bears at one end against the nut and at the other end against an element secured to the housing 1 so as to tend to urge the regulating member 13 away from its idling speed position. A restrictor pin 66 extends as a close sliding fit through the extension sleeve 63, with clearance through the bore 59 in the stem 12, as a close fit in the reduced part of the bore 59 and into the passage 60 through the regulating member 13. The restrictor pin 66 is formed intermediate its length with an annular flange 67 and is surrounded by a control spring 68 which abuts at one end against the inner end of the extension sleeve 63 and at its other end against the flange 67 to tend to urge the latter into engagement with or towards the shoulder 61 formed in the bore 59 in "the stem 12. It will be seen that movement of the restrictor pin 66 relative to the stem 12 will vary the loading of the control spring 68 and simultaneously varythe distance by'which-the inner endof the pin 66 extends into the passage 60 30 as to vary the resistance to fluidflow Which the passage 60 alfords. v

The 'co-axial bore 11a is enlarged at its outer end as at 11b and is threaded to receive a threaded bush 69.v having an annular flange 69a 'formed on its outer surface substantially, midway of its length, this flange being adapted to seat in an oil-tight manner against the outer surface of the housing 1 when the bush 69 is threaded into the enlarged bore 11b. A cup-shaped housing 6% is threaded internally at its open end and is screwed on to the bush 69 so that its open end seats on the flange, 69a in. an. oil-tight manner to form an oiltight chamber into which fuel may leak from the spill chamber 3 but is prevented from escaping from the pump.

The outer end of,.the" restrictor pin 66 extends in an oiltight manner through the closed end of the cupshaped housing69b and is surrounded by a spring 70 and has a nut 71 threaded thereon to compress the spring 70 which bears at one end against the nut 71 and at the other end against the closed end of the housing 69b to tend to withdraw the inner end of the restrictor pin 66 from vthe. passage 60 in the regulating member 13.

The operation of thepurnp will now be briefly described. As has previously been described, the axial position of the regulating member 13 controls the. position of. the.

sleeves 17 on their respective pistons 7' and by determining at what point in the stroke of the respective pistons 7 the radial bores 7b clear the sleeves 17, the axial position of the regulating member 13 determines the effective length of the stroke of the pistons 7 and regulates the speed of the engine supplied by the pump. As the radial bores 7b clear their respective sleeves 17, fuel is spilled into the chamber 3 and tends to return to the chamber 2a through the passage 60. The effective cross-sectional area of the passage 60 is however reduced by the inner end of the restrictor pin 66 which extends into the passage, such that the restricted passage 60 affords a resistance to the flow of fuel from the chamber 3 to the chamber 2a, this resistance being a function of the distance by which the inner end of the restrictor pin 66 extends into the passage and the effective crosssectional area of the latter throughout this distance. Thus this resistance may be made to vary linearly with the distance through which the restrictor pin extends into the passage 60 by making the inner end of the restrictor pin 66 cylindrical or it may be made to vary as any desired function of this distance by suitably shaping the inner end of the restrictor pin 66 or by suitably shaping the passage 60. In the example illustrated the inner end of the restrictor pin 66 is tapered to substantially frusto-conical form. It will be apparent that the inner end of the restrictor pin 66 must have such a crosssection as to be capable of entering the passage 60.

The resistance offered by the restricted passage 60 to the flow of fuel from the chamber 3 to the chamber 2a will cause a pressure to build up in the chamber 3 which is a function of the quantity of fuel spilled into the chamber 3, i. e. a function of the speed and loading of the engine supplied by the pump and also a function of the resistance afiorded by the restricted passage 60.

Thus if the restrictor pin 66 is set to a predetermined axial position, the control spring 68 will move the regulating member to a corresponding axial position to control the delivery of the pistons 7 and also, by virtue of the loading on the control spring 68 control the resistance to fluid flow of the passage 60 determined by the relative axial positions of the restrictor pin 66 and the regulating member 13. Thus axial movement of the restrictor pin 66 controls the engine speed. In practice therefore the engine speed is controlled by suitable means, e. g. a foot-pedal connected to the outer end of the restrictor pin to vary its axial position. Once the engine has been set to run at a given speed it will be seen that if the speed of the engine departs from this given speed, e. g. is reduced owing to a heavy loading of the engine, the pressure in the spill chamber will drop to produce a corresponding drop in the pressure difference across the diaphragm 55 which will therefore actuate the regulating member in the sense to increase the delivery of the pistons 7 to oppose the variation in the engine speed, and thus provide a self-governing action. Such actuation of the regulating member simultaneously varies to a small extent the loading of the control spring 68 and the resistance offered by the restricted passage, i. e. in the present example, reduces the loading of the spring 68 and increases the resistance to fluid flow of the passage 60 thus tending to reduce the pressure difference across the diaphragm 55 to provide a stabilising effect and prevent hunting. This arrangement therefore provides an automatic stable self-governing action whereby the pump operates to maintain the speed of the engine supplied thereby at a constant value which is determined by the axial position of the restrictor pin 66. Thus for any given setting of the restrictor pin 66, a balance is reached between the loading of the control spring 68 and the resistance to fluid flow of the passage 60.

It will be appreciated that the pressure prevailing in the spill chamber 3 at any given position at the regulating member 13 at a fixed engine speed is a function of thepressure drop across the restricted passage 60 and the pressure prevailing in the chamber 2a. Thus any variation in the pressure of the fuel in the chamber 2a produces a corresponding variation in the pressure prevailing in the spill chamber 3 for a constant pressure difference across the restricted passage 60 and the governing action is therefore independent of variation in the pressure of the fuel supplied to the chamber 2a.

When it is desired to vary the engine speed, the axial position of the restrictor pin 66 is adjusted accordingly to vary simultaneously the loading of the control spring and the resistance to fluid flow of the passage 60. This causes the regulating member 13 to be actuated to assure a new axial position determined by a balance which is reached between the loading of the control spring 68 and the pressure difference across the flexible wall 55 acting on the regulating member 13 and so sets the pump to operate at a new selected speed.

The regulating member 13 is shown in Figure 1 in the position for obtaining the normal maximum effective stroke of the piston 7. In this position a :pin 72 secured to the regulating member 13 abuts against an extension 73 of a spindle 74 which extends from the spill chamber to the exterior of the housing, the outer end being secured to a lever 75 which is movable between stops 76 secured on the housing 1 to rotate the spindle 74. This arrangement provides a means whereby the maximum effective stroke of the pistons 7 may be increased slightly for starting the engine when cold. In order to start the engine from cold the lever 75 is moved between the stops 76 to rotate the spindle 74 and move an extension 73 out of engagement with the pin 72 to allow the regulating member 13 to move axially in the direction to increase the effective stroke of the pistons 7. As soon as the engine starts the regulating member assumes the position to which it is set by the setting of the restrictor pin 66 and a torsion spring is preferably provided to rotate the spindle 74 to its normal position in which the extension 73 will engage the pin 72 as the regulating member reaches its position corresponding to the normal maximum effective stroke of the pistons 7.

It will be appreciated that the stabilising effect described with reference to the construction illustrated in Fig. 1 is not an essential feature of the present invention and the pump may be modified where so desired to exclude this feature. Figure 3 illustrates such a modification and, as many parts are similar to corresponding parts described and illustrated in Fig. l, the same reference numerals are employed for like parts. In this case the partition member 20 is formed centrally with an axially extending cylindrical wall 77 having an axial bore 78 therethrough, the diameter of the latter being equal to, or slightly greater than the maxi-mum diameter of the operative end 79 of the restrictor pin 66 which extends into this bore 78. The operative end 79 of the restrictor pin is again shown as frusto-conical but it could be cylindrical or of any other desired configuration which will provide the desired variation in the restricting effect of the passage 78 for axial movement of the operative end 79 of the restrictor pin 66 relative thereto. The cylindrical wall 77 is surrounded by a coaxial annular wall 80 upstanding from that face of the regulating member 13 remote from the stem 12, the flt between this wall 80 and the cylindrical wall 77 being such as to permit axial movement of the regulating member 13 relative to the cylindrical wall 77 whilst maintaining a fluid seal bet-ween the two parts. If desired auxiliary sealing means may be provided. The stem 12 of the regulating member 13 has a coaxial bore 59 extending therethrough as in the previous example and in this case the diameter of the stem 12 is reduced as at 12b adjacent the regulating member 13 so that the reduced part may extend with clearance into the sleeve 58. The reduced part 12b of the stem 12 is formed with a pair of radial bores 81 so that the spill chamber 3 is always in communication with the passage 78 by way of the radialbores 81 and the bore 59.

I j Thejend tifj thei stm IIZ remote from .the' It:

member 13is'c'losed bya threaded cap ,SZWhichiSjfortnfidlj. centrally with an aperture. 83 through which .the.- re.-.

strictor pin extends with clearance into the bore 59 with its operative end 79 extending into the passage 78in the partition member 20. The end of the restrictor pin remote from the operative'end extends as a sliding fit through a fluid'seal 84 to the exterior of the housing fr operation by suitable means, e. g. a foot-pedal to control.

the delivery of the pump. The control spring 68 extends between the cap 82 and the annular flange 67 secured on the pin 66. Theannular flexible diaphragm 55 is secured at its inner edge to the annular wall 80 of the regulating member 13 and at its outer edge to the partition member One side of the diaphragm is exposed to the introlled as in the previous example, by suitable means, e.=g.

a foot-pedal, which operates to move the restrictor pin 66 axially relative to the regulating member 13, movement in one direction to reduce the engine speed simultaneously reducing the loading of the control spring 68 and increasing the restricting effect of the passage 78 restricted by the operative end 79 of the restrictor pinand movement in the other direction to increase the engine speed simultaneously increasing the loading on the control spring 68 and reducing the restricting effect of the restricted passage 78. As shown in Figure 3 the restrictor pin is in its idling speed position with a minimum loading of the control spring and maximum restricting effect of the restricted passage 78. Any variation in the speed of the engine from that to which it isset by the pump will produce a corresponding variation in the pressure prevailing in the spill chamber 3 which will influence the diaphragm 55 automatically to move the regulating member 13 in the sense to oppose such variations in the engine speed. It will be seen however, that this movement of the regulating member 13 whilst varying to a small extent the loading of the control spring 68 will not produce any variation of the restricting eifectof the restricted passage 78 as there is no corresponding movement of the operative end 79 of the restrictor pin 66 relative to the partition member 20. Consequently, there is no feed-back or stabilising eflect.

The pump illustrated in Figure 1 may be modified as shown in Figure 4- without departing from the scope 'of the invention. In this modification the flexible wall'55, annular collar 56 and the radial bores 54 of the first con struction are omitted and provision is made in the form of a flat 12a formed on the surface of the stem 12 to ensure that the chamber 86 provided by the. cup-shaped housing 6% is in free communication with the chamber 3 so that the pressures prevailing in the

chambers

3 and 86 are equal. In this modified construction the pressureresponsive means is constituted by the stem 12, regulating member 13, ring 14 and spigot part 52 which act in effect as a piston which is subjected at one end to the pressure prevailing in the spill chamber 3 and at the other end to the pressure prevailing in the chamber 2a, the difference in these pressures producing a movement of the regulating member 13 corresponding to that produced in the first construction by the flexible wall 55.

The pump illustrated in Fig. 5 is a modification of that illustrated in Fig. 3 and is similar in many respects thereto. In this case the flexible diaphragm 55 is omitted and the annular wall on the regulating member 13 is a close sliding fit in the annular space 90 between the cylindn'dalwall i bnlmefilberr v2o .cbiiillywith the cylindrical wall 71. Thejend faceiof the annular wall 80 :isthus. exposed. to. thepressure prevailing ,in the: chamberv 2a .by. means of theQpassages 85, extending through the partition member. Theend of the, stem 12 remote from the. regulating member 13 is closed bya threaded cap 82 as in the example describedwith reference toFig. 3 but in this case.-

' erture 93 through'whichthe pin66 extends. The closed emen't 92 is .forn"1ed with an' end of the cylin drica annularriml94 bet niwhich. and the cap 82 is disposed the part 6821 of t hespring.v Thep art 68b of, the spring] extends between the closed end of the cylindrical element 92 andthe' end face of the cylindrical wall 77 such that normally when the engine is 'under load, the spring 6812 urges the cylindrical element 92 against the cap 82 against the efiect of the spring 68a so as to tend to urge the regulating member 13 in the direction to reduce spill and increase the engine speed. The restrictor pin 66 is'formed with an annular shoulder 66a which is so dimensioned relative" to the aperture" 93 in the closed end 'of the cylindrical element 92 as to be incapable of passingftherethrough. The pump is shown in Fig. 5 at a setting corresponding to low engine speeds e. g idling speed, in which the shoulder 66a of the pin 66 engages the closedend of the cylindrical element 92 and holds the'latter in a po'sition spaced from the cap 82. In this position the' spring part 68b has no effect on the regulating member 13 and thespring part 68a acts as the control spring tending to urge the regulating member 13 to the position corresponding to maximum delivery of the pump. "If the restrictor pin 66 is moved downwardly to'increase' hte restricting effect of the bore 78 and reduce the idling peed the loading on the spring part 68a. is reduced whilst if the restrictor pin 66 is moved upwardly to reduce the restricting effect of the bore 73 v and to increase the idling speed, the loading on the spring part 68a is increased. Further upward movement of the pin 66 to increase the delivery of the pump causes the cylindrical'lelement 92 to bear against the cap 82 after which the compression of the spring part 68a still tends to urge the regulating member towards the position for maximum delivery but does" not vary with movement of the regulating member 13 and the spring part 6812 takes over efiective control. It will be seen therefore that at low engine speeds variations in the setting of the pump by movement of the restrictor pin 66 produce a simultaneous variationin the restricting effect and the loading ofthe spring part 6841 whereas at higher engine speeds variation of the setting of the pump by movement of'the restrictor 'pin 66 merely controls the restricting etfect of the bore 78.

Although the presentinvention has been described by way of example as applied to a fuel injection pump in which the pumping assemblies are arranged equidistant from the axis of the pump it will be appreciated, that the invention is equally applicable to pumps of other constructions, e. g. pumps in which the pumping assemblies are arranged in lines.

The example described with reference to Fig. 5 may be modified, if desired, by forming a small passage indicated at 95 through the cylindrical wall .77 so that in the no load setting of the regulating member 13 the interior of the spill chamber is placed in communication with the passage 78.

The passage 95 is normally closed at low engine speeds e. g. idling speeds, by the operative end of the restrictor pin 66 but the latter is formed with a flat or recess in the face adjacent the passage 95 which fiat or recess is in "attrapeziumraaeaistnia.

constant communication with the low pressure region of the pump and which is so arranged as to place the passage 95 in communication With the low-pressure region upon movement of the restrictor pin 66 in the direction to increase the speed of the pump and reduce the restricting effect of the passage 78. The communication of the .spill chamber 3 with the low pressure side of the pump by way of the passage 95 and the flat or recess on the operative end of the restrictor 66 provides a form of negative feed-back, the characteristic of which may be controlled by suitably controlling the shape or configuration of the fiat or recess. Thus the latter may be tapered in such manner as to increase the feedback effect with movement of the restrictor pin to increase the engine speed or it may be of constant dimensions and arranged to extend for a limited length in the axial direction of the pin 66 to provide a range of speeds corresponding to settings of the restrictor pin 66 over which range the feed-back effect will be operative. At the same time it will be appreciated that the feed-back effect of the passage 95 is also controlled by the loading of the engine in as much as when the loading increases the regulating member 13 will move from the position shown in Fig. 5 to a position in which the annular wall 80 obscures the passage 95 to make the latter inoperative.

What I claim is:

1. A fuel injection pump for an internal combustion engine comprising a pump housing, a fuel inlet connection on the exterior of said housing, at least one pump cylinder located within the housing, a piston reciprocable within each cylinder, a fuel passage connecting said fuel inlet connection to each cylinder, a spill passage in each piston, a spill chamber formed in the housing, an element slidable on each piston in its direction of reciprocation to determine the point in the stroke of the piston at which the spill passage therein will be placed in communication with the spill chamber, a regulating member operatively connected to each sliding element and mounted within the spill chamber for displacement in said direction, a passage connecting said fuel passage to said spill chamber, a restrictor pin extending into said connecting passage to restrict the flow of fuel therethrough and operable externally of the housing to set the pump for a predetermined engine speed by controlling the flow of fuel from the spill chamber through the connecting passage to the fuel passage to produce a back pressure within the spill chamber which is a function of the amount of fuel spilled therein, means responsive to the difference in the pressures prevailing in said spill chamber and said fuel passage respectively and operative to adjust the position of said regulating member in said direction in accordance with the magnitude of said difference, and spring means disposed between said restrictor pin and said regulating member tending to urge the latter towards a position correspond-ing to maximum delivery of the pump and arranged such that, at least for low engine speeds, variation of the setting of the pump by movement of the restrictor pin in the sense to increase the engine speed simultaneously reduces said restricting effect of said pin in said connecting passage and increases the loading in said spring means and movement of the restrictor pin in the sense to reduce the engine speed simultaneously increases said restricting effect and reduces the loading on said spring means.

2. A fuel injection pump for an internal combustion engine comprising a pump housing, a fuel inlet connection on the exterior of said housing, at lease one pump cylinder located within the housing a piston reciprocable within each cylinder, a fuel passage connecting said fuel inlet connection to each cylinder, a spill passage in each piston, a spill chamber formed in the housing, an element slidable on each piston in its direction of reciprocation to determine the point in the stroke of the piston at which the spill passage therein will be placed in communication with the spill chamber, a regulating member operatively connected to each sliding element and mounted within the spill chamber for displacement in said direction, a passage at least a part of which extends through said regulating member connecting said fuel passage to said spill chamber, a restrictor pin extending into said part of said connecting passage to restrict the flow of fuel therethrough and operable externally of the housing to set the pump for a predetermined engine speed by controlling the flow of fuel from the spill chamber through the connecting passage to the fuel passage to produce a back pressure within the spill chamber which is a function of the amount of fuel spilled therein, means responsive to the difference in the pressures prevailing in said spill chamber and said fuel passage respectively and operative to adjust the position of said regulating member in said direction in accordance with the magnitude of said difference, and spring means disposed between said restrictor pin and said regulating member tending to urge the latter towards a position corresponding to maximum delivery of the pump and arranged such that, at least for low engine speeds, variation of the setting of the pump by movement of the restrictor pin in the sense to increase the engine speed simultaneously reduces said restricting effect of said pin in said connecting passage and increases the loading in said spring means and movement of the restrictor pin in the sense to reduce the engine speed simultaneously increases said restricting effect and reduces the loading on said spring means, and movement of said regulating member under the influence of said pressure difference in the sense for increasing the delivery of the pump produces simultaneously an increase in said restricing effect and a reduction in the loading of said spring means and movement of said regulating member in the opposite sense produces simultaneously a reduction in said restricting effect and an increase in the loading of said spring means.

3. A fuel injection pump for an internal combustion engine comprising a pump housing, a fuel inlet connection on the exterior of said housing, a plurality of pump cylinders located within the housing with their axes parallel to each other, a piston reciprocable within each cylinder, a fuel passage connecting said fuel inlet connection to each cylinder, a spill passage in each piston, a spill chamber r' formed in the housing, an element slidable on each piston in a direction parallel to said axes to determine the point in the stroke of the piston at which the spill passage therein will be placed in communication with the spill chamber, a regulating member operatively connected to each sliding element and mounted within the spill chamber for displacement in said direction, a passage connecting said fuel passage to said spill chamber, a restrictor pin extending into said connecting passage to restrict the flow of fuel therethrough and operable externally of the housing to set the pump for a predetermined engine speed by controlling the fiow of fuel from the spill chamber through the connecting passage to the fuel passage to produce a back pressure within the spill chamber which is a function of the amount of fuel spilled therein, means responsive to the difference in the pressures prevailing in said spill chamber and said fuel passage respectively and operative to adjust the position of said regulating member in said direction in accordance with the magnitude of said difference, and spring means disposed between said restrictor pin and said regulating member tending to urge the latter towards a position corresponding to maximum delivery of the pump.

4. A fuel injection pump for an internal combustion engine comprising a pump housing, a fuel inlet connection on the exterior of said housing, a plurality of pump cylinders located within the housing with their axes parallel to and equally spaced from a common axis, a fuel passage connecting said fuel inlet to each cylinder, a piston reciprocable within each cylinder, a spill passage in each piston, a spill chamber formed in said housing,

anelenie'nt' slidable'o eachfpiston in a direction parallel tos aid'conimenaxis 'tddete'rffiine thepinrin the stroke of the piston at which the spill passage therein will be placed in communication with the spill chamber, a common regulating member mounted fordisplacement in said direction and comprising a disc disposed in said spill chamber and operatively connected to each sliding element and a hollow stem extending from one face of said disc, a passage connecting said spill chamber'to said fuel passage, a restrictor pin extending into said hollow stem and into said connecting passage to restrictthe flow of fuel through the latter and operable externally I of the housing to set the pump for a predetermined engine speed by controlling the flow of fuel from the spill chamber through the connecting pas sage to the fuel passage to produce a backpressure within the'spill chamber which is a function of the amount of fuel spilled therein, means responsive to, the diiierencehin the pressures prevailing in said ;spill chamber and'saidfuel passage respectively and operative to adjust the position of said regulating member in said direction inacc orclan ce with the magni tude of said difference, an abutment on said restrictor pin and compression spring means surrounding said restrictor pin and operative between saidj abutment and saidregulating member to tend to, urgethe latter towards a position correspondingto maximum delivery of the pump, the

loading of said spring means, at least for low. engine speeds, being increased by simultaneous operation of the restrictor pin in the sense to reduce said restricting effect of said restrictor pin in said connecting passage to increase the engine speed and being reduced by simultaneous opera: tion of said restrictor pin in the opposite sense to reduce the engine speed.

5. A pump according toclaim 4 wherein a.fixed abutsaid pressure responsive means comprises a spigot part formed on the other face of said disc and extending as a'close sliding fitwithin said sleeve so that the regulating member is subjected to both the pressure prevailing in the spill chamber and that prevailing in said fuel passage and is responsive to the difference in said two pressures and at least a part of said connecting passage comprises a passage extending through said spigot part and said disc to the interior of said hollow stem, said restrictor pin extending into said part of said connecting passage.

7. A fuel injection pump comprising a pump housing, a fuel inlet connectionon the exterior of said housing, a plurality of pump cylinders located within the housing with their axes parallel to each other, a piston reciprocable within each cylinder, a fuel passage connecting said fuel inlet connection to each cylinder, a spill passage in each piston, a spill chamber formed in the housing, an ele ment slidable on each pistonin a'direction parallel to said axes to determine'the point in the stroke of the piston at which the spill passage therein will be placed in'communication with the spill chamber, a regulating member mounted for displacement in said direction and comprissage through said fixed abutment, a passage connecting, saidgfuel passage tosaicl spilLcchamber, a restrictor pin extending into said hollow stem and into said connecting passageto restrict the flow of fuel therethroug h an able externally of the housing to se'fth'e" nnrproraprw determined engine speed by controlling the flow of fuel from the spill chamber through the connecting passagev to the fuel passage to produce a back pressure within the spill chamber which is a function of the amountof fuel spilled therein, a flexible wall connecting said regulating member to said fixed abutment and, exposed on'onc face to the pressure prevailing in said spill chamber, 'a fur! ther passage formed through said spigot part'wherebythe other face of said flexible wall is exposed to the pressure prevailing in said fuel passage, and, compression spring means disposed around said restrictor'pin and operative between the latter and said regulating member to 'tendto urge the regulating membertowards a 'positioncorresponding to maximum delivery of-the pump and arranged I such that, at least for low engine speeds, variation of the setting of the pump by movement of the restrictor. piri'in the sense to increase the engine speed s'imuuaneoi nya- 1. duces said restricting effect of saidpinlin' saidcorinec'tingl passage and increases the loading tins said spring Qmeans: and movement of the restrictor-pinin the sense to re-. duce the engine speed simultaneouslyincreases said. re stricting effect and reduces the loading on said spring means. ii

8. A fuel injection pnmpcomprisingia pump housing, a fuel inletconnection on the exterior of said housing,.a plurality of pump cylinders. located within the housing with their axes parallel to each other, a piston reciprocable Within each cylinder, a fuel passage connecting said fuel inlet connection to each cylinder, a spill passage in each piston, a spill chamber formed in said housing, an element slidable on each piston in a direction parallel to said axes to determine the point in the stroke of the piston at which the spill passage therein will be placed in porn-r; munication With the spill chamber, a regulating member mounted for displacement in said direction and comprise ing a disc disposed in said spill chamber and operatively, connected to each sliding element and a hollow stem ex-, tending from one face of said disc, a fixed abutment in said spill chamber, a sleeve secured to said fixed abutment, the passage through said sleevecontinuing through said fixed abutment, a spigot part formed on theoth face of said disc and extending as a close sliding fit wit A in said sleeve, a flexible wall connecting said regulating member to said fixed abutmentand exposed on one fside to the pressure prevailing in said spillchamber, a @615} necting passage extending'throu gh s aid spigotgpart disc and said hollow stemto said spillfchamber' tdplace; the latter in communication with said fuel passage, a further passage formed in said spigotpart and co rnmuni-i, eating at one end with said connecting passage and at the other end with the other side of said flexible wall where by said other side thereof is exposed to the pressure; prevailing in said fuel passage, a restrictor pin extending into said stem and into said connecting passage to restrict the flow of fuel from one side of said flexible wall to, the other and operable externally of said housing to set the pump for a predetermined engine speed by controlling the flow of fuel fromi the spill chamber through; the; connecting passage to the fuel passage to produce a back pressure within thespill' chamber which is a' func-"- tion of the amount of fuel spilled therein, an abutment formed on said restrictor pin "and disposed within said sleeve, a further abutment provided on said stem towards 1 the end thereof remote from said disc and compression spring means disposed between' said abutment on said restrictor pin and said further abutment to tend to urge: said regulating member to a position corresponding t6" maximum delivery of the pump, movement of said restric tor pin relative to said regulating m'ernberin one sensein t tor pin relative to said regulating member in the opposite sense in said direction simultaneously decreasing the loading of said spring means and increasing said restricting effect.

9. A fuel injection pump comprising a pump housing, a fuel inlet connection on the exterior of said housing, a plurality of pump cylinders located within the housing with their axes parallel to each other, a piston reciprocable within each cylinder, a fuel passage connecting said fuel inlet connection to each cylinder, a spill passage in each piston, a spill chamber formed in said housing, an element slidable on each piston in a direction parallel to said axes to determine the point in the stroke of the piston at which the spill passage therein will be placed in communication with the spill chamber, a regulating member mounted for displacement in said direction and comprising a disc disposed in said spill chamber and operatively connected to each sliding element and a hollow stem extending from one face of said disc, a fixed abutment in said spill chamber, a sleeve secured to said fixed abutment, the passage through said sleeve continuing through said fixed abutment, to place said spill chamber in communication with said fuel passage, a spigot part formed on the other face of said disc and extending as a close sliding fit into said sleeve whereby said regulating member is subjected to both'the pressure prevailing in said spill chamber and the pressure prevailing in said fuel passage and is responsive to the difference of these two pressures, at connecting passage extending through said spigot part, said disc and said stem to said spill chamber to place the latter in communication with said fuel passage, a restrictor pin extending into said stem and into said connecting passage to restrict the flow of fuel from one side of said flexible wall to the other and operable externally to said housing to set the pump for a predetermined engine speed by controlling the fioW of fuel from the spill chamber through the connecting passage to the fuel passage to produce a back pressure within the spill chamber which is a function of the amount of fuel spilled therein, an abutment formed on said restrictor pin and disposed within said sleeve, a further abutment provided on said stem towards the end thereof remote from said disc and compression spring means disposed between said abutment on said restrictor pin and said further abutment to tend to urge said regulating member to a position corresponding to maximum delivery of the pump, movement of said restrictor pin relative to said regulating member in one sense in said direction simultaneously increasing the loading of said spring means and reducing the restricting effect of said pin in said passage and movement of the restrictor pin relative to said regulating member in the opposite sense in said direction simultaneously decreasing the loading of said spring means and increasing said restricting effect.

10. A fuel injection pump comprising a pump housing, a fuel inlet connection on the exterior of said housing, a plurality of pump cylinders located within the housing with their axes parallel to each other, a piston reciprocable within each cylinder, a fuel passage connecting said fuel inlet connection to each cylinder, a spill passage in each piston, a spill chamber formed in said housing, an element slidable on each piston in a direction parallel to said axes to determine the point in the stroke of the piston at which the spill passage therein will be placed in communication with the spill chamber, a regulating member mounted for displacement in said direction and comprising a disc disposed in said spill chamber and operatively connected to each sliding element and a hollow stem extending from one face of said disc, an annular wall formed on the other face of said disc, the passage through said wall extending through said disc to the interior of said stem, a further passage connecting the interior of said stem with said spill chamber, a fixed abutment in said spill chamber, a hollow sleeve secured to said fixed abutment and extending as a close sliding fit into said annular wall, the passage through said sleeve extending through said abutment and communicating with the passage through said wall and said disc to place said spill chamber in communication with said fuel passage, a restrictor pin extending into said stern and into said hollow sleeve to restrict the flow of fuel through the latter from the spill chamber to the fuel passage, and operable externally of said housing to set the pump for a predetermined engine speed by controlling the flow of fuel from the spill chamber through said sleeve to said fuel passage to produce a back pressure within said spill chamber which is a function of the amount of fuel spilled therein, a flexible Wall connecting said regulating member to said fixed abutment and exposed on one face to the pressure prevailing in the spill chamber a still further passage in said abutment whereby the other face of said flexible wall is exposed to the pressure prevailing in said fuel passage, an abutment on said restrictor pin and disposed within said stern, a further abutment on said stem towards the end thereof remote from said disc and compression spring means disposed between said abutment on said restrictor pin and said further abutment to tend to urge said regulating member to a position corresponding to the maximum delivery of the pump, movement of said restrictor pin relative to said sleeve in the sense to reduce the restricting effect of said pin in said sleeve simultaneously increasing the loading of said spring means, movement of said restrictor pin in the opposite sense simultaneously reducing the loading of said spring means, displacement of said regulating memher in said direction in the sense to increase the engine speed simultaneously reducing the loading of the said spring means and displacement of said regulating member in the opposite sense simultaneously increasing the loading of said spring means.

11. A fuel injection pump comprising a pump housing, a fuel inlet connection on the exterior of said housing, a plurality of pump cylinders located within the housing with their axes parallel to each other, a piston reciprocable within each cylinder, a fuel passage connecting said fuel inlet connection to each cylinder, a spill passage in each piston, a spill chamber formed in said housing, an element slidable on each piston in a direction parallel to said axes to determine the point in the stroke of the piston at which the spill passage therein will be placed in communication with the spill chamber, a regulating member mounted for displacement in said direction and comprising a disc disposed in said spill chamber and operatively connected to each sliding element and a hollow stern extending from one face of said disc, an annular wall formed on the other face of said disc, the passage through said wall extending through said disc to the interior of said stem, a further passage connecting the interior of said stem with said spill chamher, a fixed abutment in said spill chamber, a first hollow sleeve secured to said fixed abutment with the passage through said sleeve extending through said fixed abutment and communicating with said fuel passage, a second hollow sleeve surrounding said first hollow sleeve to define an annular chamber within which said annular wall extends as a close sliding fit, the spill chamber communicating with the fuel passage through the passage through said first sleeve, a still further passage formed through said fixed abutment placing said annular chamber in communication with said fuel passage whereby said regulating member is subjected to both the pressures prevailing in said spill chamber and that prevailing in said fuel passage and is responsive to the difference of these two pressures, a restrictor pin extending into said stem and into said first hollow sleeve to restrict the flow of fuel through the latter from the spill chamber to thefuel passage and operable externally of the housing to set the pump for a predetermined engine speed by con troll-ing the flow of fuel from the spill chamber through said first hollow sleeve to said fuel passage to produce a back pressure within said spill chamber which is a function of the amount of fuel spilled therein, an abutment aerate pin or said further abutment, a first compression spring disposed between said further abutment and said movable element tending to urge said movable sleeve away from said'further abutment and a second compression spring disposed between said movable element and said first hollow sleeve tending to urge said movable element towards both the abutment on the restrictor pin and said further abutment, said second spring being operative at settings of said'restrictor pin corresponding to low engine speeds to urge said movable element into engagement with said abutment on said restrictor pin whilst said first spring tends to urge said regulating member to the position corresponding to maximum delivery of the pump such that'movement of'said restrictor pin in the one sense to reduce the restricting effect thereof in said first hollow sleeve tends to increase the loading of said first spring and movement of said restrictor pin in the oppositesense tends to increase said loading of the first spring, whilst at settings of said restrictor pin corresponding to high engine speeds said second spring is operative to urge said movable element into engagement with said further abutment to tend to urge said regulating member to a position corresponding to maximum delivery of the pump.

12. A pump according to claim 11 wherein a feedback passage is provided in the wall of said first hollow sleeve to place the interior of the latter in communication with said spill chamber, said feed-back passage being providedat a location such that it is capable of being at least partially closed by said restrictor pin and by said annular Wall, :said restrictor pin being movable from a position corresponding to low engine speeds at which it does not obstruct said feed-back passage to a position corresponding'to high engine speeds at which it closes said feedback passage and said regulating member being displaceable from a position corresponding to a low engine load at which it does not obstruct said feed-back passage to a positioncorresponding to a high engine load at which it closes said feed-back passage.

13.A fuel injection pump for an internal combustion engine comprising a pump housing, a fuel inlet con nection on the exterior of said housing, a plurality of pump cylinders located within the housing with their axes parallel to each other, a piston reciprocable within each cylinder, a fuel passage connecting said fuel inlet connection to each cylinder, a spill passage in each piston, a spill chamber formed in the housing, an element slidable on each piston in a direction parallel to said axes to determine the point in the stroke of the piston at which the spill passage therein will be placed in communication with the spill chamber, a regulating member mounted for displacement in said direction in accordance with the difference in the pressures prevailing in said spill chamber and said fuel passage respectively, said regulating member comprising a disc mounted in said spill chamber and operatively connected to each sliding element and a hollow stem extending away from one face of said disc, a passage connecting said fuel passage to saidispill chamber, a restrictor pin. extending into said stem and having an operative end extending into said connecting passage to restrict the flow of fuel therethrough and Operable externally of the housing to set the pump for a predetermined engine speed by moving said operative end relative to said connecting passage to vary the restricting effect thereof and to control the flow of fuel from the spill chamber through the connecting passage to the fuel passage to produce a back pressure within the spill chamber which is a function of the amount of fuel predetermined function of the pump setting, and spring means disposed between said restrictor pin and said regulating member'tending to'urge the latter towards a position corresponding to maximum delivery of the pump and arranged such that, at least for low engine speeds, variation of the setting of the pump by movement of the restrictor pin in the sense to increase the engine speed simultaneously reduces said restricting effect of said pin in said connecting passage and increases the loading in said spring means and movement of the restrictor pin in the sense to reduce the engine speed simultaneously increases said restricting effect and reduces the loading on said spring means. e

14. A fuel injection pump for an internal combustion engine comprising a pump housing, a fuel inlet connection on the exterior of said housing, a plurality of pump cylin-' ders located within said housing with their axes parallel to each other, a piston reciprocable in each cylinder, a} fuel passage connecting said fuel inlet connection to each cylinder, a spill passage in each piston, a spill chamber formed in said housing, an element slidable on each piston in a direction parallel to said axes to determine the point' in the stroke of the piston at which the spill passage therein will be placed in communication with the spill chamber, a regulating member mounted for displacement chamber, a restrictor pin extending in said stem and into said connecting passage to restrict the flow of fuel therethrough and operable externally of the housing to set the pump at a predetermined engine speed by controlling the flow of fuel from the spill chamber through the connecting passage to the fuel passage to produce a back pressure within the spill chamber which is a function of the amount of fuel spilled therein, and compression spring means disposed between said restrictor pin and said stem tending to urge said regulating member to a position corresponding to maximum delivery of the pump said restrictor pin being movable in said direction in said j one sense to reduce the restricting effect thereof in said connecting passage and simultaneously to increase the, loading in said spring means and movable in said direction; in said opposite sense to increase said restricting efiect, and simultaneously to reduce the loading in said spring means. 15. A fuel injection pump for an internal combustion engine comprising a pump housing, a fuel inlet connection on the exterior of said housing, at least one pump cylinder located within the housing, a piston reciprocable Within each cylinder, a fuel passage connecting said fuel inlet connection to each cylinder, a spill passage in each piston, a spill chamber formed in the housing, a common regulating member associated with each piston and displaceable to determine the point in the stroke of each piston at which the spill passage therein will be placed in communication with the spill chamber, a passage connecting said fuel passage to said spill chamber, a restrictor pin extending into said connecting passage to restrict the flow of fuel therethrough and operable externally of the housing to set the pump for a predetermined engine speedby controlling the fiow of fuel from the spill chamberthrough the connecting passage to the fuel passage to produce a back pressure within the spill chamber whichis a function of the amount of fuel spilled therein, means responsive .to the difference in the pressures prevailing in said spill chamber and said fuel passage respectivelyland operative to. :adjust theposition of said regulating member;

" in accordance withtheflmagnitude of said difference, and:

spring means disposed between said restrictor pin and said regulating member tending to urge the latter towards a position corresponding to maximum delivery of the pump and arranged such that, at least for low engine speeds, variation of the setting of the pump by movement of the restrictor pin in the sense to increase the engine speed simultaneously reduces said restricting effect of said pin in said connecting passage and increases the loading in said spring means and movement of the restrictor pin in the sense to reduce the engine speed simultaneously increases said restricting effect and reduces the loading on said spring means.

16. A fuel injection pump for an internal combustion engine comprising a pump housing, a fuel inlet connection on the exterior of the housing, at least one pump cylinder located within the housing, a piston reciprocable Within each cylinder, a fuel passage connecting said fuel inlet connection to each cylinder, a spill passage in each piston, a spill chamber formed in the housing, a common regulating member operatively associated with each piston to determine the point in the stroke of each piston at which the spill passage therein will be placed in communication with said spill chamber and displaceable to vary said point, a passage connecting said fuel passage to said spill chamber, a restrictor pin extending into said connecting passage to restrict the flow of fuel therethrough and operable externally of the housing to set the pump for a predetermined engine speed by controlling the flow of fuel from the spill chamber through the connecting passage to the fuel passage to produce a back pressure within the spill chamber which is a function of the amount of fuel spilled therein, means responsive to the difference in the pressures prevailing in said spill chamber and said fuel passage respectively and operative to adjust the position of said regulating member in accordance with the magnitude of said difference, and spring means operatively associated with both said regulating member and said restrictor pin tending to urge said regulating member to a position corresponding to maximum delivery of the pump and arranged such that, at least for low engine speeds, variation of the setting of the pump by movement of the restrictor pin in the sense to increase the engine speed simultaneously reduces said restricting effect of said pin in said connecting passage and increases the loading in said spring means and movement of the restrictor pin in the sense to reduce the engine speed simul- 18 taneously increases said restricting effect and reduces the loading on said spring means.

17. A fuel injection pump for an internal combustion engine comprising a pump housing, a fuel inlet connection on the exterior of the housing, a plurality of pump cylinders located within the housing with their axes parallel to each other a piston reciprocable within each cylinder, a fuel passage connecting said fuel inlet connection to each cylinder, a spill passage in each piston, a spill chamber formed in the housing, a common regulating member operatively associated with each piston to determine the point in the stroke of each piston at which the spill passage therein will be placed in communication with said spill chamber and displaceable to vary said point, a passage connecting said fuel passage to said spill chamber, a restrictor pin extending into said connecting passage to restrict the flow of fuel therethrough and operable externally of the housing to set the pump for a predetermined engine speed by controlling the flow of fuel from the spill chamber through the connecting passage to the fuel passage to produce a back pressure within the spill chamber which is a function of the amount of fuel spilled therein, means responsive to the difference in the pressures prevailing in said spill chamber and said fuel passage respectively and operative to adjust the position of said regulating member in accordance with the magnitude of said difference, and spring means operatively associated with both said regulating member and said restrictor pin tending to urge said regulating member to a position corresponding to maximum delivery of the pumps and arranged such that, at least for low engine speeds, variation of the setting of the pump by movement of the restrictor pin in the sense to increase the engine speed simultaneously reduces said restricting effect of said pin in said connecting passage and increases the loading in said spring means and movement of the restrictor pin in the sense to reduce the engine speed simultaneously increases said restricting effect and reduces the loading on said spring means.

References Cited in the file of this patent UNITED STATES PATENTS 2,093,477 Parsons Sept. 21, 1937 2,567,367 Deschamps Sept. 11, 1951 2,688,286 Friedlander Sept. 7, 1954