US3744465A

US3744465A - Hydraulic shuttle vavle for fuel injection pumps

Info

Publication number: US3744465A
Application number: US00220203A
Authority: US
Inventors: J Voss; A Jeney
Original assignee: Ambac Industries Inc
Current assignee: Ambac Industries Inc; AIL Corp
Priority date: 1972-01-24
Filing date: 1972-01-24
Publication date: 1973-07-10
Anticipated expiration: 1990-07-10
Also published as: CA967441A; DE2303012A1; NL7300774A; IT977018B; FR2169141A1; GB1386191A; NL155633B; DE2303012C3; FR2169141B1; JPS4883218A; DE2303012B2; JPS5234686B2

Abstract

The output of a fuel injection pump plunger is alternately directed to a pair of injection nozzles by a hydraulically actuated shuttle valve. A shuttle housing incorporated into the high pressure circuit includes a bore containing the valve shuttle which is reciprocated by alternating fuel pressure introduced at each end of the bore. The alternating pressurized fuel is supplied to the bore in timed relationship with the reciprocation of the pump''s plunger by a rotary distributor driven by the pump cam shaft. Means are provided in the shuttle to interconnect the shuttle actuating and the injection pump high pressure passages during the intervals between fuel injection to establish a controlled low pressure level in the high pressure passages prior to the next injection.

Description

'[ 1 July 10,1973

Primary Examiner-Laurence M. Goodridge Assistant Examiner-Cort R. Flint Anorneyl lowson and Howson [57] ABSTRACT The output of a fuel injection pump plunger is alternately directed to a pair of injection nozzles by a hydraulically actuated shuttle valve. A shuttle housing incorporated into the high pressure circuit includes a bore containing the valve shuttle which is reciprocated by alternating fuel pressure introduced at each end of the bore. The alternating pressurized fuel is supplied to the bore in timed relationship with the reciprocation of the pumps plunger by a rotary distributor driven by the pump cam shaft. Meansare provided in the shuttle to interconnect the shuttle actuating and the injection pump high pressure passages during the intervals between fuel injection to establish a controlled low pres- INJECTION PUMPS Inventors: James R. Voss, Wilbraham; A.

Frank Jeney, Westfield, both of Mass. 1 v Assignee: AMBAC Industries, Inc., Springfield, 11]. Jan. 24, 1972 123/139 AM, 123/139 AL F02m 41/04 123/139 R, 139 AL, 123/139 AM References Cited UNITED STATES PATENTS Umted States Patent 1 Voss et a1.

[ HYDRAULIC SHUTTLE VAVLE FOR FUEL [22] Filed:

211 Appl. No.: 220,203

[52] US. Cl.

[51] Int.

[58] Field of Search..................

w n. r. p u a .u g F M g m m w w w 1 v p m w m m e C m n .m

dn 0 kn C e m sm R LR w w 199w] /33 311 3 2 2 133 1 22 11 mm m m amm mm t H a "m n ms m amn-MO n.1..n ACPLC 540069 66552 99999 11111 Ill/l 689 7 24 77 0 65 3 3 3290 94522 1 2 3322'- 1 HYDRAULIC SHUTTLE VAVLE FOR FUEL INJECTION PUMPS The present invention relates generally to fuel injection equipment and relates more specifically to a hydraulic shuttle valve for diesel fuel injection pumps which serves to alternately direct the output of a pumping plunger between two fuel injection nozzles.

The present invention is directed to the type of fuel injection system wherein the injection nozzles are supplied with fuel which is pumped and metered at a central fuel injection pump remote from the nozzles. In this type of system, the timing as well as the metering is .controlled by the pump, and the nozzles valve opens,

usually against spring pressure, only during the brief pumping interval to admit the pumped fuel quantity to a combustion chamber. The fuel is pumped at extremely high pressures, commonly between 5,000 and 20,000 psi, in order to effect the proper nozzle operation and fuel atomization. v

Fuel injection pumps of the category described enjoy commercial popularity in three general types. In a first type, a separate single plunger pump is provided for each combustion chamber. This type is particularly adapted for use with large stationary diesels wherein the distance between cylinders would preclude the use of a single centrally located pump with its fuel distribution conduits.

ln a second type of pump, a single pumping element actuated by a multilobed cam shaft is utilized to supply a plurality of engine cylinders by combining a distributor arrangement into the high pressure circuit. Typically, the pumping plunger is rotated and reciprocated, and suitable distributor slots in the rotating plunger direct the pump output sequentially to the engine cylinders. The fuel metering function is carried out by a fuel control sleeve on the plunger to selectively uncover a port communicating with the pumping chamber.

The third type of pump, and that to which the present invention is directed, is characterized by a central pump unit from which fuel is distributed through conduits to the individual .combustion chambers, and wherein a separate pumping plunger is provided for each engine cylinder, the plungers commonly being arranged in line and driven by a common cam shaft. Fuel metering is accomplished by rotation of the plungers to vary the beginning or ending (or both) points of the plunger stroke utilized for high pressure pumping. This type of pump, while more expensive to build than the rotating distributor-plunger type pump described above, is recognized as a more dependable, longer lasting and generally superior pump and is preferred for engine fuel control where cost is not an overriding factor.

The present invention permits the utilization of the individual plunger type pump with only half the number of plungers required with the conventional installation. This is accomplished by alternately directing the output of a given pumping plunger to one'or the other of two fuel injection nozzles. The broad concept of dividing the output of a pumping plunger is not new, as evidenced by the disclosure of U. S. Pat. No. 1,720,657 wherein an attempt was made to mechanically link a spool valve to the pump drive shaft. It is not believed, however, that such a system has been successfully operated or would be commercially feasible in view of the complexity of the mechanical linkage, the difficulty of maintaining small high pressure volumes, and the diffirocate the shuttle in timed relationship with the plunger pumping strokes. A fluid passage arrangement is provided within the shuttle for directing the pressurized shuttle-actuating fuel into the idle fuel delivery passages. Similarly, passage means in the shuttle are provided to pressurize the fuel delivery conduit between the shuttle and the pump delivery valve as the shuttle passes over center. These arrangements serve to suppress cavitation erosion damage within the fuel passages and may permit the elimination of the fuel delivery valve by maintaining a constantly filled condition of the delivery passages. Further, by maintaining con-.

stantly filled high pressure lines at the beginning of injection, the stroke to stroke variation of fuel injection quantity and timing is reduced, with beneficial reduction in overall smoke and other exhaust pollutants. An added advantage of the latter passage arrangement is the prevention of damage to the system should the shuttle'happen to stop over center when the engine operation is interrupted;

It is accordingly a first object of the present invention to provide new and useful improvements in fuel injection equipment.

A further object of the invention is to provide an arrangement for dividing the output of a fuel injection pump plunger between two fuel injection nozzles.

Another object of the invention is to provide apparatus as described including means for maintaining a consistent pressurized condition of the idle fuel discharge passages throughout the operating range of the engine.

A still further object of the invention is to provide a hydraulically actuated shuttle valve for dividing the output of the fuel injection pump plunger between two fuel injection nozzles.

A still further object of the invention is to provide apparatus as described including means for maintaining a pressurized condition of the fuel delivery passage between the delivery valve and the shuttle valve during the interval between plunger injection strokes v Still another object of the invention is to provide a hydraulically actuated valve. as described including means for preventing damage to the system upon stopping of the valve member in an over center position.

A still further object of the invention is to provide apparatus as described which will provide substantial economies in the manufacture of fuel injection pumps and which will provide a more compact pump by halving the number of pumping plungers required for a given number of engine cylinders.

Additional objects of the invention will be more readily apparent'from the following. detailed description of embodiments thereof when taken together with the accompanying drawings wherein:

FIG. 1 is a schematic perspective view showing a fuel injection pump embodying the present invention to permit a single pumping plunger to alternately direct fuel to one or the other of a pair of fuel injection nozzles;

FIG. 2 is an end elevational view partly in section of a fuel injection pump showing the supply pump and distributor embodying the present invention as schematically illustrated in FIG. 1;

FIG. 3 is a sectional view taken along line 33 of FIG. 2 showing the interior details of the pump;

FIG. 4 is an enlarged sectional view taken along line 4-4 of FIG. 3 showing details of the hydraulic head including the shuttle valve;

FIG. 5 is a reduced scale view taken along line 5-5 of FIG. 2 and showing the interior passages for the shuttle-actuating fuel;

FIG. 6 is a reduced view partly in section taken along line 6-6 of FIG. 3 showing the fuel passages leading from the rotary distributor toward the shuttle;

FIG. 7 is a greatly enlarged view of the distributor shuttle as shown in FIG. 4 with the shuttle positioned so as to direct a flow of injected fuel through the right hand delivery passage',

FIG. 8 is a view similar to FIG. 7 with the shuttle positioned to direct a flow of injected fuel through the left hand delivery passage;

FIG. 9 is a view similar to FIG. 7 but showing a modified form of shuttle;

FIG. 10 is a view similar to FIG. 8 but showing the modified shuttle of FIG. 9;

FIG. 11 is a view showing the shuttle of FIGS. 7 and 8 in an over center position;

FIG. 12 is a view similar to FIGS. 8 and10 showing a further modified form of shuttle;

FIG. 13 is a view similar to FIGS. 7 and 9 showing the modified form of shuttle of FIG. 12 and FIG. 14 is a view similar to FIG. 11 showing the further modified form of shuttle of FIGS. 12 and 13 in an over center position.

Referring to the drawings and particularly the schematic view of FIG. 1, a single plunger fuel injection pump is illustrated embodying the present invention to alternately direct the pump output to a pair of

fuel injection nozzles

22 and 24. The nozzles, by means of the

nozzle holders

22a and 24a, would be mounted so as to extend into the combustion chambers of an internal combustion engine for the purpose of introducing an atomized spray of fuel in a quantity metered by the pump in accurately timed relationship with the cylinder piston movements. The nozzles are remotely located from the pump 20 and are connected thereto by the respective discharge conduits 22b and 24b as schematically illustrated in FIG. 1. The nozzles are of the type which open in response to an increase in pressure in the discharge conduits and close upon the drop in pressure following delivery of a metered quantity of fuel. Since the nozzles, nozzle holders and the discharge conduits are conventional in every respect, there is no need for a further detailed description thereof.

The pump 20 includes a plunger 26, the upper end of which extends into the barrel 28 of the pump to effect a pumping of fuel therefrom in a conventional manner. The plunger 26 is driven in reciprocation by cam lobes 30 on the pump cam shaft 32 which is coupled to the engine to which the pumped fuel is delivered. A roller tappet 34 on the lower end of the plunger 26 bears against the cam lobes 30 and is maintained in contact with the cam surface at all times by the plunger spring 36. The spring is seated at its upper end against the spring seat 40 fixedly mounted in the pump housing and the lower spring seat 42 on the plunger adjacent the tappet 34. As will be explained in more detail hereinafter, a controll sleeve 44 having a gear segment thereon and a downwardly depending cylindrical portion 46 is rotatable by a control rack to rotate the plunger and thereby control the metering of the 48 which are axially slidable in slots 50 of the sleeve portion 46.

The pump structure described thus far is conventional. The present invention involves the novel arrangement for dividing the pump fuel output between the injection nozzles in a reliable, synchronized manner which will maintain a pressurized condition of the idle fuel delivery and discharge conduits as well. In the embodiment illustrated, the invention includes a shuttle housing 52 located above the delivery valve and adapted to receive the output of the pumping plunger 26 through a fuel delivery passage 54. A horizontal shuttle bore 56 in the shuttle housing contains the shuttle 58 which in a manner described hereinafter directs the flow of fuel from the passage 54 alternately to the

distributor passages

60 or 62 which respectively connect by means of

unions

60a and 60b with the conduits 22b and 24b to carry the fuel to the injection nozzles.

The shuttle 58 is reciprocated within the bore 56 by a hydraulic control system. This system as shown schematically in FIG. 1, includes

conduits

64 and 66 opening into the ends of the bore 56, which conduits lead to a distributor generally designated 68. The distributor includes a cam shaft driven distributing member in the form of a pump gear 140 having pressurized fuel and drain

chambers

162 and 164 respectively which are adapted to alternately communicate with the conduits 64 and 77 to thereby alternately supply pressurized fuel to the opposite ends of the bore 56. This produces a reciprocating movement of the shuttle 58 in accurately timed relation with the plunger pumping strokes.

The above description of the schematic view of a pump embodying the invention is provided to give a broad understanding of the structural arrangement of a pump embodiment. For a detailed understanding of the invention and particularly the arrangement for maintaining a pressurized condition of the idle fuel delivery and discharge passages, a detailed description of specific embodiments are provided herebelow.

Referring to FIGS. 2 and 3, the preferred embodiment illustrated therein is accorded the same identifying numerals for corresponding parts as the schematic illustration of FIG. 1. The pump 20 is mounted within a pump housing 76 having a central perpendicular bore 78 within'which the plunger 26 is mounted for reciprocation. Acam shaft compartment 80 in the lower end of the housing 76 accommodates the cam shaft 32 which is journaled therewithin. The compartment 80 is closed at the right hand end of the pump as viewed in FIG. 3 by the cover plate 82 bolted to the housing. Similarly, the opposite end of the compartment 80 is closed by the cover plate 84 which includes an inwardly extending portion 86 on which are mounted the seals 88 for separating the lubricating oil in the cam shaft chamber from the fuel in the distributor and governor chamber. The shaft 32 is coupled directly to the engine supplied with fuel by the pump and is driven at half engine speed for a four cycle engine or at engine speed for a two cycle engine.

lower end of which is disposed within the upper end ofthe bore 78. An upper portion 100 of the sleeve 98 is 4 accommodated by the enlarged bore 102 coaxial with bore 78. The upper end 104 of the sleeve 98 is flanged for securing to the upper end of the housing 76 by suitable means (not shown). I

A pumping chamber 106 is formed within the bore 94 of barrel 28 by the top of the plunger 26 and the delivery valve holder 108 disposed within the sleeve 98 above the barrel28. A delivery valve 110 of conventional construction is located within the valve holder 108 and serves to admit fuel to the delivery passage 54 of the shuttle housing 52 during the high pressure pumping portion of the plunger stroke. The shuttle housing 52 is secured above the delivery valve holder 108 within the double threaded securing ring 112.

The means for rotating the plunger 26 to effect a nietering of the high pressure fuel output of the plunger includes a control rack 114 extending horizontally through the housing 76 for connection with the engine governor. The rack 114 engages the teeth of the gear segment on control sleeve 44 which rotates about a downwardly depending cylindrical portion 116 of the barrel 28. The cooperative elements of the plunger for coupling the plunger for rotation with the control sleeve 44 are clearly shown in FIG. 3 and include the annular land 118 of the plunger from which the lugs 48 extend for sliding cooperation with the slots 50 in the portion 46 of the control sleeve.

Referring to FIG. 4, an annulus 120 near the upper end of the plunger 26 communicates with the pumping chamber 106 by means of a vertical slot 122 in the plunger. The plunger is relieved above the annulus 120 and adjacent the slot 122 to form a helical shoulder 124 adapted to cooperate with a fuel spill port 126 in the barrel 28. A fill port 128 in the barrel opposite the spill port 126 communicates as does the spill port with an fuel sump 130 formed between the outer sleeve 98 and the housing bore 102. The fuel pump 130 is supplied with fuel under pressure from a fuel supply pump 138.

The fuel supply pump assembly 138 as best shown in FIG. 2 is a gear type including a lower gear element 140 and a smaller upper gear element 132. The intermeshing teeth of the

elements

140 and 142 pressurize fuel introduced therebetween from fuel inlet 146, the high pressure fuel being passed into the fuel outlet 144. As shown in FIG. 3, the gear element 140 is mounted and keyed on the stub shaft 148 which is journaled within is driven by the splined connection of stub shaft 148 with the cam shaft 32. The upper gear element 142 is secured to and drives the governor shaft 158 which extends into the adjacent engine governor (not shown). Sandwiched between the fuel supply pump housing 156 and the cover plate 84 is the distributor porting plate 160, the function of which will shortly become apparem.

The fuel supply pump 138 and specifically the gear element 140 thereof incorporates a distributor for the hydraulic actuation of theshuttle to alternately direct pressurized fuel to the

fuel passages

64 and 66. The distributor includes an arcuate pressurized shuttle drive fuel distribution chamber 162 and a diametrically opposed arcuate shuttle drain chamber 164 in the gear element'140. The shuttle drive fuel distribution chamber 162 communicates at all times with a fuel supply port 166 in the distribution plate 160 which by means of a passage 168 in the plate 84 as shown in FIG. 6 connects with a passage 170 (FIG. 5) which joins with the fuel supply passage 171 as shown in FIGS. 4 and 5. A port '172 in the housing joins the passage 171 with the sump 130, which is supplied with pressurized fuel from'the fuel supply pump outlet 146 by suitable housing passages (not shown); An annular groove 173 in the gear element 140 passing outside the drain chamber 164 is located on the same radiusas the supply port 166 and hence supplies the shuttle drive distribution chamber 162 with pressurized fuel at all times. A passage 175 in the plate 84 supplies a flow of lubricating fuel'to the stub shaft 148.

The shuttle drain chamber 164 as shown in FIGS. 2, 3 and 6 communicates with a drain port 176 in the distributor plate 160 which in turn opens into the drain passage 177 in the cover "plate 84 from which fuel passes into the housing sump through passage 178. An annular groove 180 in the gear element on the same radius as the drain port 176 keeps the drain chamber 164 in constant communication with the drain port 176.

Annular grooves

173 and 180 opposed from the

grooves

173 and 180 are provided to balance the fuel pressure forces on each side of the gear element 140.

The opposite ends of the shuttle housing bore 56 ar alternately supplied with pressurized fuel from the distribution chamber 162 and drained of the shuttle displaced fuel by communication with drain chamber 164 by a labyrinth of passages making up the

fuel delivery passages

64 and 66 of the schematic FIG. 1. Considering first the passage 64 which in the position illustrated both in the schematic view of FIG. 1 and the detailed illustrations of FIG. 2-6' is in communication with the drain chamber 164, the passage comprises a port 64a in the distributor porting plate leading to the vertical passage 64b in the cover plate 84, this in turn opening into the passage 64c and 6411 in the housing side cover which through port 64e in the housing communicates with annulus 64f of the sleeve 98. A port 64g in the sleeve 98 leads from the annulus 64f to an annulus 64h in the delivery valve holder 108. A vertical passage 64: in the delivery valve holder alignswith a similar passage 64j in the shuttle housing which opens into an annulus 64k at one end of the shuttle bore56.

Similarly, the passage 66 connecting the distributor with the opposite end of the shuttle housing plunger bore includes a port 66a in the distributor porting plate; I

passage 66b in the coverplate 84. passage 66c in the housing, passage 66d in the housing side cover plate,

port 66e in the housing, annulus 66f and port 66g in the sleeve 98, an annulus 66h between the sleeve 98 and the delivery valve holder, vertical passages 66i and 66] respectively in the delivery valve holder and shuttle housing, and the annulus 66k in one end of the shuttle housing bore 56.

The shuttle drive fuel distribution chamber 162 and the drain chamber 164 are arranged with diametrically opposed and radially aligned ends and the

ports

64a and 66a are diametrically located with respect to the center of rotation of the gear element 140 with the result that the

ports

64a and 66a are simultaneously opened to communication with the fuel and drain chambers. Accordingly, when one end of the shuttle housing bore 56 is opened to drain, the other end is supplied with pressurized fuel. For example, as illustrated in FIG. 2 with the gear element 140 rotating in a clockwise direction, the port 66a is open to the distribution chamber 162 so that pressurized fuel is delivered to the annulus 66k through the ports and passages 66h-j. Simultaneously, the port 64a is open to the drain chamber 164 and the annulus 64k through ports and passages 64b-j has opened the opposite end of the shuttle housing bore to the drain sump. Since the fuel distribution chamber 162 and drain chamber 164 have the same arcuate extent, the

ports

64a and 66a will be simultaneously opened and closed to the pressurized fuel and drain chambers.

Referring to FIG. 4 and the enlarged views of FIGS. 7, 8 and 11, the shuttle valve assembly includes a generally cylindrical shuttle element 182 having an axial bore 184 therein. The bore 184 includes a smaller diameter portion 184a at the right end which opens into a larger diameter portion 184b at the conical shoulder 186. The sleeve 188 disposed within the larger bore portion 184k terminates inwardly in a conical end 190. A ball 192 is slidably disposed between the sleeve end 190 and the shoulder 186 and is adapted to cooperate with the conical sleeve end and shoulder to seal their respective circumscribed bore passages.

The outer surface of the shuttle element includes

circumferential grooves

194 and 196 of substantial axial length adjacent the ends of the shuttle and a central intermediate circumferential groove 198 disposed therebetween and divided therefrom by

lands

200 and 202. Radial ports 204 in the groove 198 provide communication between the groove and the bore 18% in the region traversed by the ball 192 between the ball limit positions.

A snubbing arrangement is provided at each end of the shuttle housing bore 56 to prevent the destructive impact of the shuttle at the ends of its strokes. The snubbing means includes

inserts

206 and 208 secured within the bore 56 at the opposite ends thereof.

Radial passages

210 and 212 respectively in the

inserts

206 and 208 communicate with the annuli' 64k and 66k in the shuttle housing. Axailly inwardly directed

cylindrical portions

214 and 216 of the

inserts having passages

218 and 220 therein respectively connect the

passages

210 and 212 with the shuttle housing bore 56. The ends 222 and 224 of the shuttle element respectively include

axial counterbores

226 and 228 which are adapted to receive the

portions

214 and 216 of the

inserts

206 and 208. The fuel trapped between the inserts and shuttle ends radially outwardly of the

portions

214 and 216 provides a damping effect preventing an undesirable impact of the shuttle ends with the inserts at the end of each shuttle stroke.

For operation of the pump, the cam shaft 32 is connected to the engine to be supplied with fuel and the shaft 158 is connected to an adjacent governor in a conventional manner. The

unions

60a and 60b are joined by lengths of. discharge tubing to the injection nozzles in the manner shown schematically in FIG. 1. The control rack 114 is connected to the governor to provide a metering control of the pump output.

During operation, the rotation of the cam shaft 32 and the cam lobes 30 carried thereby provide reciprocating motion of the plunger 26, the cam lobes through tappet 34 moving the plunger upwardly while the return spring 36 serves to hold the tappet in engagement therewith and provide downward movement of the plunger. Fuel introduced into the inlet 146 from a suitable source (not shown) is pressurized by the fuel supply pump 138 and is conducted from the pump outlet 144 to the fuel supply annulus by internal housing passages (not shown). When the upper face of the plunger 26 opens the ports 126 and 128m the pumping chamber 106, the chamber as well as the annulus 120 and slot 122 are filled with fuel. On the upstroke of the plunger, the

ports

126 and 128 are closed by the plunger and the fuel in the pumping chamber 106 is pumped through the delivery valve 110 into the delivery passage 54. The fuel quantity delivered is controlled by the rotational disposition of the plunger since the helical shoulder 124 determines the end of delivery by opening the spill port 126, thus permitting fuel in the pumping chamber to drain through the slot 122 into the fuel sump 130. Upon opening of the spill port 126, the delivery valve 110 closes until reopened upon the succeeding pumping stroke. The rotation of the plunger to effect the metering of the fuel is carried out by the governor through movement of the control rack 1 14 which rotates the control sleeve 44, the depending portion 46 of which rotates the plunger lugs 48 engaged in the slots 50 thereof. The arrangement of fuel pumping and metering control as briefly described above is well known in the art and further description thereof is accordingly unnecessary.

The metered quantities of fuel injected by the plunger into the delivery passage 54 are alternately directed into one or the other of the

passages

60 and 62 and hence into the

injection nozzles

22 and 24 by the shuttle assembly 58. In the schematic view of FIG. 1 and in the views of the specific embodiment of FIGS. 2-8 and 9, the fuel pump gear element is positioned to supply pressurized fuel through the ports and passages 66a-k to the right-hand side of the shuttle bore 56 as most readily seen in FIG. 7. The introduction of pressurized fuel to the right-hand end of the shuttle bore moves the ball 192 to the left limit position within the shuttle element, the ball seating against the conical end of the sleeve 188 thereby sealing the passage within the sleeve. The shuttle is then moved by the pressurized fuel to the left against the left-hand insert 206, the shuttle being snubbed by the trapped fuel outside of the portion 214 of the insert.

With the shuttle in the position shown in FIG. 7, the fuel injected by the plunger passes through the passage 54 into the groove 196 of the shuttle element which is in communication with the passage 62 leading to the nozzle 24. During the injection flow into passage 62, the passage 60 is maintained filled with pressurized fuel fuel injection into the passage 62 and conduit 24b serves to reduce cavitation erosion and improve the uniformity of .injection.

Should the end of injection leave a high residual pressure instead of the cavities, communication between passage 60 and the shuttle groove 198 serves as a pressure relief instead of fill. In either case, by the time of the beginning of the next injection, the high pressure passages will contain supply pressure.

Following the completion of injection to the nozzle 24, the rotation of the gear element 140 opens the ports and passages 66a,k to drain chamber 164 and the ports and passages 64a-k to the pressurized fuel chamber 162. The introduction of pressurized fuel through the insert 210 to the left side of the shuttle housing bore 56 first moves the ball 192 to the right-hand limit position against shoulder 186 following which the shuttle element moves to the right-hand position shown in FIG. 8 against the insert 208, being snubbed thereagainst in the same manner described above with respect to the insert 206. As the shuttle element moves across fuel delivery passage 54 as shown in FIG. 11, the annular groove 198 communicates with the passage 54 and, by means of ports 204 and the shuttle bore, supplies pressurized fuel from the distributor to the delivery passage. Accordingly, the delivery passage 54 in a manner similar to that described above with respect to the passage 60, is maintained in a filled pressurized condition to minimize cavitation erosion and improve the injection uniformity.

Following movement of the shuttle to the right-hand position shown in FIG. 8, the fuel injected through the fuel delivery passage 54 passes into the groove 194 of the shuttle which in this position communicates with both the passage 54 and the passage 60 to deliver the fuel into passage 60, the conduit 22b, and the nozzle 22. At the same time, the intermediate groove 198 of the shuttle, element is in communication with the passage 62 and accordingly by means of ports 204 maintains a pressurized condition of the passage 62 and conduit 24b to maintain a filled condition of the passage and conduit for the purpose described above.

In the event that the shuttle element should stop in a central position such as that shown in FIG. 11, it is important that means be provided to prevent damage to the system should injection incur before the shuttle element has been advanced to a limiting position against one of the shuttle housing bore inserts. Should injection occur with the shuttle element in the position shown in FIG. 11, the injected fuel will enter the intermediate shuttle groove 198, pass through the ports 204 into the shuttle bore, and thence through the ports and passages 64a-k to the distributor 68 and ultimately the fuel supply pump 138. Since the fuel supply pump is a positive displacement type pump, an output pressure regulator is necessary (not shown) and serves to relieve the otherwise destructive pressure buildup which might occur upon dead heading" of the shuttle. It will be apparent that the width of the

lands

200 and 202 cannot exceed the diameter of the passage 54 since otherwise there would be a possibility of one of the lands completely blocking the passage.

Should the engine start with the shuttle over center as in FIG. 11 and the injection begin with the ball 192 at its opposite limit position from that shown in FIG. 11, the injection will pass into the drain'sump of the pump and will similarly not cause any damage to the pump components.

A modified embodiment of shuttle assembly is shown in FIGS. 9 and 10 wherein the shuttle element 182' is v modified in certain respects, the shuttle housing passages, and the inserts at the end of the shuttle housing bore 56 being identical with that of the above described embodiment and hence bearing the same identifying numerals. The shuttle element 182' is characterized by circumferential grooves 194' and 196' equivalent to and serving the same purpose as the

grooves

194 and 196 of the shuttle element 182. However, instead of a single intermediate circumferential groove, the shuttle element 182' includes a pair of

grooves

240 and 242 intermediate the grooves 194' and 196' and which are separated by a land 244. The element 182', instead of the through bore of the previous embodiment, includes a bore 246 extending partway thereinto from the lefthand end of the element, and a bore 248 extending thereinto from the right-hand end of the element. The

bores

246 and 248 are coaxial with the shuttle element for a length coextensive with the annular grooves 194' and 196. Bore extensions 246' and 248' respectively of the

bores

246 and 248 extend in an offset, side by side relation Radial ports 250 in the groove 2 42'connect the groove with the boreextension 246' while ports 252 connect the groove 240 with the bore extension 248'.

The operation of the modified embodiment of FIGS. 9 and 10 is in effect the same as that of the previously described embodiment, since the grooves 240 and f242 will respectively align with the

passages

60 and 62 in the limit positions of the shuttle element shown in FIGS. 9 and 10. In the left-hand shuttle limit position of FIG. 9, the injected fuel from passage 54 passes through the groove 196' and into the passage 62 while at the same time the pressurized fuel from the righthand end of the shuttle housing bore passes through bore 248, bore etension 248', ports 252 and groove 240 into the passage 60. When the pressure is reversed to the left-hand side of the shuttle housing bore, the shuttle element is moved to the right-hand limit position-shown in FIG. 10 whereupon the injected fuel passes from passage 54 through groove 194' into passage 60. Simultaneously, the pressurized fuel in the shuttle housing bore passes through bore 246, bore extension 246', ports 250, groove 242 and into the passage 62 to maintain a minimal residual pressure therein. As the shuttle element 182' passes over center, it will be evident that either the groove 240 or the groove 242 will be pressurized and will accordingly fill the idle delivery passage 54 with pressurizedfuel upon passage thereacross. The embodiment of FIGS. 9 and 10 accordingly carries out the same functions as the preceding embodiment. I I

In FIGS. 12-14, a still further embodiment of the shuttle assembly is illustrated wherein the shuttle housing, including the shuttle housing bore, passages and inserts are identical with those shown in the two preceding embodiments. The shuttle element 182" is considerably simpler than the preceding embodiments and does not include any type of bore. The shuttle element 182" is a cylindrical member having a central circumferential groove 260 therein of sufficient axial extent to communicate with both the

passages

60 and 62 when the shuttle is in an intermediate position such as shown in FIG. 14.

Grooves

266 and 268 adjacent the shuttle element ends are balancing grooves to assure a uniform bearing of the element against the shuttle housing bore wall.

In the position shown in FIG. 12 wherein the shuttle element 182" is shown in its right-hand position, the injected fuel from passage 54 passes around groove 260 and into the passage 62. Upon shifting of the shuttle element to the left-hand position as in FIG. 13 in response to pressurization of the right-hand end of the shuttle housing bore, the fuel from passage 54 again passes around groove 260 over center as shown in FIG. 14, at least one and possibly both of the

passages

60 and 62 will communicate with the groove 260 and hence any injected fuel will pass into one or the other or both of the injection nozzles without damaging the pump. The likelihood of the shuttle stopping over center is remote and should it happen, the injection of fuel into an engine cylinder out of phase will not impede the starting and operation of the engine.

By extending the stroke of the embodiment of FIGS. 12-14, the filling of the

fuel discharge passages

60 and 62 by pressurized fuel between injections can be realized. However, it is not possible to fill the delivery passage 54 with pressurized fuel as is achieved by the previous embodiments. However, the shuttle of FIGS. 12-14 can be produced at considerably less expense than those of the two preceding embodiments and for many applications may prove entirely satisfactory.

The desirability of maintaining a uniform residual pressure in the fuel delivery' passages downstream of the delivery valve is well established. The retraction volume type of delivery valve provides a sharp cutoff of the fuel injection by the nozzle but it may also result in the creation of bubbles as the line pressure is sharply reduced and a resultant cavitation erosion of the ports and passages when the high injection pressures collapse the bubbles. By filling these passages with fuel at modest pressure, the collapse of the cavitation bubbles is harmless. Also by pressurizing the delivery passages through the shuttle, the uniformity of injection is significantly improved since the residual pressure level is no longer dependent on the delivery valve operation. A shuttle actuating pressure in the range of 50l00 psi has proven satisfactory for providing the necessary movement of the shuttle element as well as the filling and pressurization of the delivery passages.

So effective is the shuttle for carrying out this function, that it is possible to eliminate the delivery valve altogether in certain pump embodiments and depend upon the shuttle to maintain the filled and pressurized condition of the fuel delivery passages and conduits.

It will be obvious that the present pump, although illustrated with only a single pumping plunger, may include a plurality of plungers, all driven by a common cam shaft. The distributor 68 can be adapted to serve a number of shuttles simply by providing additional ports which alternately communicate with the distributor fuel and drain chambers. A four cylinder engine might accordingly be supplied with fuel from a two plunger pump, while an eight cylinder engine could be equipped with a four plunger pump in accordance with the invention. The economies of providing the relatively simple shuttle in place of a separate pumping plunger can be readily appreciated. Coupled with the described functional advantages, the invention can be understood to represent a significant advance in the fuel injection art.

Manifestly, changes in details of construction can be effected by those skilled in the art without departing from the spirit and scope'of the invention.

We claim 1. In a fuel injection pump adapted to intermittently supply metered quantities of high pressure fuel to a first fuel injection nozzle, the improvement comprising means for alternately directing the intermittent fuel output of said pump into a second nozzle, said means comprising a hydraulic shuttle assembly including a shuttle housing having a bore therein, a shuttle element slidably disposed in said bore, a delivery passage in said housing for introducing the fuel output of said pump into said shuttle housing bore, a pair of fuel discharge passages in said shuttle housing communicating with a said housing bore, said discharge passages being adapted for connection to conduit means for delivering fuel to said first and second fuel injection nozzles, means for establishing limit positions of said slidable shuttle element, means on said shuttle element for providing fluid communication of said delivery passage with one of said discharge passages when said shuttle element is in a first limit position in said bore and for providing fluid communication of said delivery passage with the other of said discharge pass ages when said shuttle element is in a second limit position in said bore, and means for alternately introducing pressurized fluid into the ends of said shuttle housing bore to move said shuttle element between said limit positions in said bore in timed relationship with the injection output of said pump to thereby alternately direct the pump output between said first and second fuel injection nozzles.

2. The invention as claimed in claim 1 wherein said means for alternately introducing pressurized fluid into the ends of said shuttle housing bore includes means for simultaneously draining fluid from the opposite ends of said bore.

3. The invention as claimed in claim 2 wherein said means for introducing and draining fluid from the ends of said shuttle housing bore comprises distributor means connected by conduit means to the ends of said shuttle housing bore, said distributor means being adapted to alternately connect said latter conduit means to a pressurized fluid supply and fluid drain sump, said distributor means being connected with said pump for synchronized operation therewith.

4. The invention as claimed in claim 1 wherein said shuttle element comprises a cylindrical member having a circumferential groove therein, said shuttle element groove being adapted to communicate at all times with said fuel delivery passage, said shuttle element groove being adapted in one limit position of said shuttle element to communicate with one of said discharge passages to direct fuel from said delivery passagejthereinto, said shuttle element groove being adapted in the other limit position of said shuttle element to communicate with the other of said discharge passages to direct fuel from said delivery passage thereinto.

5. The invention as claimed in claim 4 wherein said shuttle element groove is adapted to communicate with both said discharge passages when said shuttle element is positioned in an intermediate position between said limit positions.

6. The invention as claimed in claim 4 wherein said shuttle element includes a circumferential balancing groove adjacent each end of said circumferential groove, one of said balancing grooves being adapted to communicate with one of said discharge passages when the other of said discharge passages is in communication with said circumferential groove.

7. The invention as claimed in claim 1 wherein said means for establishing limit positions of said shuttle element comprises axially spaced inserts in said shuttle housing bore.

8. The invention as claimed in claim 7 including means for snubbing the movement of said shuttle element into the limit positions.

9. The invention as'claimed in claim 8 wherein said snubbing means comprises means on said inserts adapted to cooperate with the ends of said shuttle element to trap'fluid therebetween and thereby prevent destructive contact of said shuttle element with said inserts.

10. The invention as claimed in claim 1 wherein said pressurized fluid introduced into the ends of said shuttle housing bore comprises fuel.

11. The invention as-claimed in claim 10 wherein said means for alternately introducing the pressurized fuel into the ends of said shuttle housing bore includes means for simultaneously draining fluid from the opposite ends of said bore. I

12. The invention as claimed in claim 11 wherein said means for introducing and draining fuel from the ends of said shuttle housing'bore comprises distributorv meansconnected by conduit means to the ends of said shuttle housing bore, said distributor means being adapted to alternately connect said latter conduit means to a pressurized fuel supply and fuel drain sump, said distributor means being connected with said pump for synchronized operation therewith.

13. The invention as claimed in claim 12 wherein said pressurized fuel supply comprises the fuel pump fuel supply.

14. The invention as claimed in claim 12 wherein said distributor means comprises a rotary distributor driven by said pump.

15. The invention as claimed in claim 11 shuttle element comprises a cylindrical member having first and second axially spaced circumferential grooves therein, said first shuttle groove being adapted to communicate with said delivery passage and one of said discharge passages when said shuttle element is in a first limit position, said second shuttle groove being adapted to communicate with said delivery passage and the ing the idle fuel delivery and discharge passages comprises an intermediate circumferential groove in said shuttle element between said first and second circumferential grooves, said intermediate groove being adapted to communicate with one of said discharge passages when the other of said passages is communicating with one of said first or second shuttle element grooves in a limit position of said shuttle element, and means in said shuttle element for connecting said intermediate groove with the pressurized end of said shuttle housing bore. 1

. 18. The invention as claimed in claim 17 wherein said latter means comprises an axial bore in said shuttle, port means connecting said intermediate shuttle groove with said axial bore, and valve mean for closing said shuttle bore between said intermediate groove port means and the drained end of said shuttle housing bore whereby pressurized fuel passes from the pressurized end of said bore through the shuttle bore, port means and intermediate groove into one of said discharge passages to fill and maintain an above atmospheric residual fuel pressure in said passage.

' 19. The invention as claimed in claim 18 wherein said intermediate groove is adapted to communicate with said delivery passage as said shuttle element moves between said limit positions to thereby fill and maintain a residual pressure in said delivery passage.

20. The invention as claimed in claim 16 wherein said shuttle element passage means for filling and pressurizing the idle fuel delivery and discharge passages comprises a pair of intermediate circumferential grooves in said shuttle element between said first and second shutwherein said other of said discharge passages when said shuttle element is in a second limit position.

16. The invention as claimed in claim 15 wherein said shuttle element includes passage means therein for filling and pressurizing the idle fuel delivery and discharge passages with pressurized fuel from the shuttle housing bore.

17. The invention as claimed in claim 16 wherein said shuttle element passage means for filling and pressuriztle element grooves, a bore extending from each end of said shuttle element partway thereint'o, passage means connecting one of said intermediate shuttle element grooves with one of said shuttle element bores, passage means connecting the other of said shuttle element intermediate grooves with the other of said shuttle element bores, said intermediate grooves and shuttle element bores being disposed and related so that in a first limit position of the shuttle element one of said intermediate grooves communicates with the idle discharge passage and connects the passage with the pressurized end of said shuttle housing bore, and wherein in the second shuttle element limit position the other of said intermediate shuttle element grooves connects the other of said discharge passages with the opposite pressurized end of said shuttle housing bore.

21. The invention as claimed in claim 20 wherein said intermediate shuttle element grooves are adapted to communicate with said delivery passage as said shuttle element moves between said limit positions to thereby fill and maintain a residual pressure in said delivery passage.

22. The invention as claimed in claim 15 including means for relieving injection pressure should the shuttle element stop between limitpositions with neither the first nor second groove thereof in communication with said delivery passage.

Claims

1. In a fuel injection pump adapted to intermittently supply metered quantities of high pressure fuel to a first fuel injection nozzle, the improvement comprising means for alternately directing the intermittent fuel output of said pump into a second nozzle, said means comprising a hydraulic shuttle assembly including a shuttle housing having a bore therein, a shuttle element slidably disposed in said bore, a delivery passage in said housing for introducing the fuel output of said pump into said shuttle housing bore, a pair of fuel discharge passages in said shuttle housing communicating with said housing bore, said discharge passages being adapted for connection to conduit means for delivering fuel to said first and second fuel injection nozzles, means for establishing limit positions of said slidable shuttle element, means on said shuttle element for providing fluid communication of said delivery passage with one of said discharge passages when said shuttle element is in a first limit position in said bore and for providing fluid communication of said delivery passage with the other of said discharge passages when said shuttle element is in a second limit position in said bore, and means for alternately introducing pressurized fluid into the ends of said shuttle housing bore to move said shuttle element between said limit positions in said bore in timed relationship with the injection output of said pump to thereby alternately direct the pump output between said first and second fuel injection nozzles.

4. The invention as claimed in claim 1 wherein said shuttle element comprises a cylindrical member having a circumferential groove therein, said shuttle element groove being adapted to communicate at all times with said fuel delivery passage, said shuttle element groove being adapted in one limit position of said shuttle element to communicate with one of said discharge passages to direct fuel from said delivery passage thereinto, said shuttle element groove being adapted in the other limit position of said shuttle element to communicate with the other of said discharge passages to direct fuel from said delivery passage thereinto.

9. The invention as claimed in claim 8 wherein said snubbing means comprises means on said inserts adapted to cooperate with the ends of said shuttle element to trap fluid therebetween and thereby prevent destructive contact of said shuttle element with said inserts.

11. The invention as claimed in claim 10 wherein said means for alternately introducing the pressurized fuel into the ends of said shuttle housing bore includes means for simultaneously draining fluid from the opposite ends of said bore.

12. The invention as claimed in claim 11 wherein said means for introducing and draining fuel from the ends of said shuttle housing bore comprises distributor means connected by conduit means to the ends of said shuttle housing bore, said distributor means being adapted to alternately connect said latter conduit means to a pressurized fuel supply and fuel drain sump, said distributor means being connected with said pump for synchronized operation therewith.

15. The invention as claimed in claim 11 wherein said shuttle element comprises a cylindrical member having first and second axially spaced circumferential grooves therein, said first shuttle groove being adapted to communicate with said delivery passage and one of said discharge passages when said shuttle element is in a first limit position, said second shuttle groove being adapted to communicate with said delivery passage and the other of said discharge passages when said shuttle element is in a second limit position.

17. The invention as claimed in claim 16 wherein said shuttle element passage means for filling and pressurizing the idle fuel delivery and discharge passages comprises an intermediate circumferential groove in said shuttle element between said first and second circumferential grooves, said intermediate groove being adapted to communicate with one of said discharge passages when the other of said passages is communicating with one of said first or second shuttle element grooves in a limit position of said shuttle element, and means in said shuttle element for connecting said intermediate groove with the pressurized end of said shuttle housing bore.

18. The invention as claimed in claim 17 wherein said latter means comprises an axial bore in said shuttle, port means connecting said intermediate shuttle groove with said axial bore, and valve mean for closing said shuttle bore between said intermediate groove port means and the drained end of said shuttle housing bore whereby pressurized fuel passes from the pressurized end of said bore through the shuttle bore, port means and intermediate groove into one of said discharge passages to fill and maintain an above atmospheric residual fuel pressure in said passage.

19. The invention as claimed in claim 18 wherein said intermediate groove is adapted to communicate with said delivery passage as said shuttle element moves between said limit positions to thereby fill and maintain a residual pressure in said delivery passage.

20. The invention as claimed in claim 16 wherein said shuttle element passAge means for filling and pressurizing the idle fuel delivery and discharge passages comprises a pair of intermediate circumferential grooves in said shuttle element between said first and second shuttle element grooves, a bore extending from each end of said shuttle element partway thereinto, passage means connecting one of said intermediate shuttle element grooves with one of said shuttle element bores, passage means connecting the other of said shuttle element intermediate grooves with the other of said shuttle element bores, said intermediate grooves and shuttle element bores being disposed and related so that in a first limit position of the shuttle element one of said intermediate grooves communicates with the idle discharge passage and connects the passage with the pressurized end of said shuttle housing bore, and wherein in the second shuttle element limit position the other of said intermediate shuttle element grooves connects the other of said discharge passages with the opposite pressurized end of said shuttle housing bore.

22. The invention as claimed in claim 15 including means for relieving injection pressure should the shuttle element stop between limit positions with neither the first nor second groove thereof in communication with said delivery passage.