US3752138A

US3752138A - Engine injection pump operating all cylinders or less

Info

Publication number: US3752138A
Application number: US00170178A
Authority: US
Inventors: J Gaines
Original assignee: International Harverster Corp
Current assignee: Navistar International Corp
Priority date: 1971-08-09
Filing date: 1971-08-09
Publication date: 1973-08-14
Anticipated expiration: 1990-08-14

Abstract

Multi-cylinder engine, and injection pump for operating same on a fraction of the number of cylinders, then a greater fraction of that number and, finally, all of the cylinders when operating in all higher portions of the speed range. Viewed the other way, the pump operates all cylinders at full load, and cuts a plurality or pluralities of those cylinders out of operation until, at engine idle, the transition is made such that only a plurality of cylinders is still firing, and all such transition control is consolidated in a controlled fuel metering sleeve in the pump. The pump is of the rotary distributor type, and has a variable volume pump chamber portion whereof the pump chamber number is materially fewer than the number of engine cylinders and preferably is limited to one or two pump chambers.

Description

United States Patent [191 Gaines Aug. 14, 1973 [75] Inventor: John W. Gaines, Wheaton, 111.

[73] Assignee: International Harvester Company,

Chicago, Ill.

[22] Filed: Aug. 9, 1971 [21] Appl. No.: 170,178

[52] U.S. CI. 123/139 R, 123/139 AL, 417/294,

417/462 [51] Int. Cl.. F04b 49/08, F04d 15/00, F02m 39/00 [58] Field of Search 123/139 R, 139 AB,

123/139 AR, 139 AD, 139 AL, 139 AP, 140 R, 198 F; 417/302, 462

2,771,867 11/1956 Peras 123/198 F Primary Examiner-Laurence M. Goodridge Attorney-Floyd B. Harman [57] ABSTRACT Multi-cylinder engine, and injection pump for operating same on a fraction of the number of cylinders, then a greater fraction of that number and, finally, all of the cylinders when operating in all higher portions of the speed range. Viewed the other way, the pump operates all cylinders at full load, and cuts a plurality or pluralities of those cylinders out of operation until, at engine idle, the transition is made such that only a plurality of cylinders is still firing, and all such transition control is consolidated in a controlled fuel metering sleeve in the pump. The pump is of the rotary distributor type, and has a variable volume pump chamber portion whereof the pump chamber number is materially fewer than the number of engine cylinders and preferably is limited to one or two pump chambers.

2 Claims, 9 Drawing Figures FINAL 171757? Pmmmws 3.152.138

SHEET 2 OF 5 JfiI/n 5071' John Z0. Gain 05 PAIENTEU i B55 rua I MkokhvWtR in wk whbk SHUT Off GOVERNOR 51 f f V Act VENT INCHES 1 25 2 man/f9 Ina/vim 5/107 OFF 67/07 OFF Gal [EH09 -51 [EVE DISPlAtf/VEWT "VA/C1955 lfinfen for; (foil n l. (iaz'nes ENGINE INJECTION PUMP OPERATING ALL CYLINDERS OR LESS This application relates generally to diesel engine fuel control. It especially relates to means for improving the idle speed operation of a multi-cylinder high speed low inertia compact diesel engine, with particular regard to steady speed control and low emissivity in the engine exhaust.

In a multi-cylinder engine, the cutting in and cutting out of operation of a plurality or pluralities of the cylinders enables such cylinders to burn fuel when needed, but not otherwise. The balance of the cylinders are needed as full time cylinders and are kept firing, thus maintaining high operating temperatures in the combustion chambers at all times. The non-firing plurality or pluralities are cut in and cut out of operation in an initial transition necessarily made with dispatch, with punctuality, and with exactitude, and yet without abruptness. The lack of abruptness has been found to be critical in nature, and the criticality makes it a problem.

In any case, diesel engines are generally sensitive and some diesel engines are particularly sensitive to surface operating temperatures of the exposed faces in the combustion chamber. Thermal efficiency is adversely effected when, during light load or engine idling, a critical part or parts of the combustion chamber are allowed to run comparatively cool to their normally hot operating temperature (500F. or more).

Obviously, eight cylinders can be operated, with fuel withheld at times from some and supplied full time to others, simply by providing eight individual fuel metering pumps in the pumping means. So a plurality, or set, of one or more cylinders can receive a metered amount, per stroke, of fuel differing from the amount received by another plurality or by other pluralities of the remaining cylinders.

But providing a number of differing, precision made pumps individual to cylinders of that same number makes for difficulty, if for no other reason than unnecessarily multiplying expensive precision parts to be made, and thereafter to be kept sorted so the similar but differing ones of the components are installed always in the critical places intended for, and suited to, each one. The measure of preciseness I am talking about necessitates either the lapping of the mating pumping surfaces, or else the specially grinding and then the select-fitting up of the mating pumping parts, after grinding same to required tolerances measured in the millionths of an inch.

In practice, matching a number of pumps to do identical metering for that number of engine cylinders is a problem, at any time several different portions in a speed range are involved. And so, a further problem arises by then deliberately unmatching the identical metering of the pumps to provide for such transient things as zero mm /stroke metering at times, or some initial transition flow in mm /stroke metering. Also, achieving the initial transition of fuel metering without abruptness and with a plurality of transition cylinders matched in metered fuel flow at the same time is also a problem.

On the other hand, the failure to cut out operation of some cylinders for reduced engine load would introduce the greater problem of having all cylinders firing on such small quantities of fuel that the combustion chamber temperatures would run low, and under the attendant condition of very low air swirl contributing to unreliable combustion and high emissivity in the exhaust.

My invention, of a controlled fuel metering sleeve in which transition control is consolidated for all cutting in and cutting out of cylinders, materially reduces or substantially eliminates the foregoing problems, as will now be explained. Benefits include smoother operation, lower pump cost, clearer exhaust, hotter combustion and hotter combustion chambers, higher efficiency, and reduced engine surging in the low speed range, particularly at or near idle.

In the drawings:

FIG. 1 is a longitudinal elevational view, in section, of a port metering, opposed plunger, rotary distributor, diesel fuel injection pump embodying the present invention;

FIG. 2 is the same as FIG. 1, but with only the control sleeves and associated parts shown, and with the sleeves repositioned to shut off;

FIGS. 3 and 4 show the metering control sleeve as viewed from the left rear and from the rear, respectively;

FIG. 5 is a developed sectional view taken along the lines VV of FIG. 4, as if the bore lands and grooves of the metering sleeve were unwrapped-out flat;

FIG. 6 is a sectional view taken diagonally of the sleeve bore, along the section lines VIVI of FIG. 5;

FIG. 7 is a graph of flow-displacement curves resulting from four plus four cylinder operation produced by four plus four sleeve structure in FIG. 5;

FIG. 8 corresponds to FIG. 5, and results in two plus two plus four cylinder operation produced by the structure of FIG. 8; and

FIG. 9 is the same as FIG. 7, but shows one plus one plus two plus four cylinder operation produced by a modified governor sleeve, not shown.

More particularly in FIG. I of the drawings, the housing or casing 10 for the fuel metering pump device shown has three bolted together sections consisting of a main housing 12 at one end, a primary pump housing 14 at the opposite end, and a so-called distributor head housing 16 assembled between the end sections or housings. An engine connected pump shaft 18 extends longitudinally through the device and is journaled for rotation in spaced apart roller and sleeve bearings 20 and 22, respectively, fixed in the main housing 12 and in the distributor head housing 16.

The shaft I8 is the heart of the mechanism of several operating components within the housing 10, all contributing in properly timed relation to supply metered amounts of fuel to the individual nozzles 23 which communicate with combustion chambers in cylinders of that number within an engine 24.

The shaft 18 is connected in the pump input drive 27, and a gear coupling not shown directly couples together the crankshaft of the engine 24 and the pump input drive 27. The pump shaft 18 has a longitudinally drilled passage 25 which is intersected at one end by a first transverse passage terminating in a metering port 26, and intersected at an intermediate point by a second transverse passage terminating in a timing port 28.

A centrally located charging pump component within the so-called distributor head housing 16 is shown having a diametric bore, and further having a cylindrical axial passage forming a pump chamber 30 interposed in the passage and communicating with and inter sected by the inner ends of the diametric bore.

A distributor component comprises a retraction or delivery valve 32 connected in the longitudinal passage 25 beyond the chamber so as to unseat or open in a direction away from the pump component. The distributor component further comprises a set of suction ports 34 which intersect the passage 25 on the pump chamber side of the valve 32 and which periodically communicate with an annular chamber 36 which holds the so-called transfer fuel in the housing 16. The distributor component further comprises a distributor port 38 which communicates with the passage 25 on the opposite side of the delivery valve 32 and which registers at uniformly spaced apart intervals with each of a set of housing passages 40, and a set of fuel delivery lines 42 leading to the individual nozzles 23. Socalled banjo fittings 44 connect the lines liquidtight to the distributor head housing 16, being secured to the latter by individual hollow connecting screws 46.

A dual control sleeve component times pressure pulses for the actuation of the retraction valve 32. The dual sleeve component comprises a timing sleeve 48, and another sleeve 50, variously referred to herein and elsewhere as a control sleeve, a governor sleeve, and a metering sleeve depending upon the functional relationship specifically referred to. The timing sleeve 48 rotatably receives the pump shaft 18 on a proximal portion relative to the pump chamber 30, and the metering sleeve 50 rotatably receives the shaft 18 on a distal portion between a governor component 52 and the timing sleeve 48. An alignment pin 54 connected between the

sleeves

48 and 50 holds them so as to be non-rotatable but relatively axially movable to one another. The timing sleeve 48 has a connection, not shown, to a pivoted arm termed a governor spring arm 56.

Straight milled slots 58, corresponding in number to the cylinders of the engine 24 and located in the bore of the timing sleeve 48, are parallel to the pump shaft axis and cooperate with the timing port 28 to spill fuel therefrom during short, equally spaced apart intervals. Milled right-hand helix spill grooves 60, corresponding in number to the cylinders in the engine 24 and formed in the bore of the metering sleeve 50, cooperate with the metering port 26 to control injection duration by allowing fuel to escape therefrom during short, equally spaced apart intervals in the cycles. The straight timing sleeve slots 58 keep the beginning of delivery constant whereas the milled right-hand helix spill grooves 60, when the metering sleeve 50 is adjusted by the governor component 52, perform their metering function by varying the end of fuel delivery. Operation of the governor component against a concavo-conical cup surface of the metering sleeve 50 is believed obvious, and in any case, that component 52 is already detailed in another specification owned by the same assignee, U.S. Pat. No. 3,311,100.

The charging pump component referred to provides the pressure for the timed pressure pulses closing and opening the delivery valve 32, and includes two rotary and reciprocatory pump plungers 62 mounted in opposite ends of the diametric bore so as to form two opposed pump chambers or, viewed another way, two opposite movable wall portions of one chamber 30. The charging pump component further includes a cam ring 64 fixed in the housing 16 in the plane of the pump plungers 62, a pair of rotary and reciprocatory cam followers or rollers 66 which ride along inwardly protruding cams on the ring 64, and an interposed tappet 68 connecting each roller to a different one of the plungers 62 causing the plungers to periodically foreshorten and re-expand a precompressed, interposed return spring 70 during pumping. The cams on the ring 64 correspond in number to the cylinders of the engine 24.

Further components in the device, indicated by general reference numerals, are a control component 72, a maximum torque component 74, a timing plate component 76, and a transfer or primary pump component 78.

PUMPING FIG. 1

When the device is pumping, diesel fuel from a tank 80, which fuel is ultimately drawn into the pump chamber 30, flows in a path leading through a fuel tank outlet conduit 82, a transfer intake port 84 which is in the housing 14 and which communicates with the suction side of the pump mechanism of the primary pump 78, a transfer outlet port 86 which communicates with the pressure side of the pump 78, a transfer conduit 88 leading from the outlet port 86 and including therein a final filter 90, the annular chamber 36, a communica tion charging passage 92 in the housing 16 which is connected during shaft rotation to the suction ports 34 in periodically timed relation, and a set of diagonal intake passages 94 formed in the shaft 18, and thence into the pump chamber 30.

The pump plungers 62 collapse radially toward one another on the discharge stroke of the pump, and the fuel follows a sequence flowing in different directions through a three-way split path. During predetermined initial movement of collapse of the plungers 62, fuel escapes from the shaft 18 into the pump housing 12 through the registering straight timing slot 58 until spilling of the fuel is cut off by the timing sleeve 48 covering the timing port 28. During further collapsing movement of the plungers 62, fuel pressure increases so as to unseat and open the retraction valve 32, and fuel through the unseated valve 32 is forced through the registering one of the fuel nozzle delivery lines 42. During final, radially inward collapsing movement of the plungers 62, a milled right-hand helical spill groove 60 registers with the metering port 26 so as to-terminate the duration of injection by spilling the balance of the pumped fluid into the main housing 12.

A drain conduit 96 returns a portion of the spilled fuel from the main housing 12 of the device to the fuel tank 80. A spring-loaded recirculation valve, not shown, connected between the housing 12 and the suction side of the primary pump component 78 returns another portion of the spilled fuel. Finally, a pressure regulating valve 98 connected between the annular chamber 36 and the suction side of the primary pump component 78 unseats and returns fuel to the latter whenever pressure becomes excessive on the pressure side of the pump component 78.

The delivery valve 32 functions to maintain residual pressure in each delivery line 42 after each injection takes place, doing so at that time by slightly enlarging the volume of the line in well known way as the valve retracts and reseats.

SHUTOFF FIG. 2

The dual control sleeve component is concentric to the pump shaft 18, which supports the metering sleeve 50 to turn and slide on its axis 100 and also supports the timing sleeve 48 to turn and slide on its axis 102, the

axes

100 and 102 being coaxial.

For purposes of oversimplifying and yet making more graphic hereinafter the function of the metering sleeve 50, the shutoff position of FIG. 2 shows both sleeves moved manually fullback on the shaft 18 exposing the metering port 26 and the timing port 28. Shutoff makes it clearly impossible to trap fuel in the shaft 18, because of zero duration of injection and because the start of injection is never timed for. Consequently, the plunger action cannot pressurize and deliver fuel to the cylinders, regardless of shaft rotation.

In practice, however, the excessive amount of sliding travel required by the metering sleeve 50 for shutoff is not only unnecessary but undesirable. A manual shutoff lever 104 is simply provided so as to engage the arm 56 and slide only the timing'sleeve 48 to the fullback position for shutoff, as shown in FIG. 2. Shutoff is just as absolute, in result.

FIRING ORDER ALL CYLINDERS ACTIVE A diesel engine is used in examples of my invention now to be given, the engine and examples being by way of illustration and not of limitation. Such engine, in one preferred embodiment, is a 90 V8 solid injection engine having, from front to rear, the cylinder numbering l, 3, 5, 7 in the left bank and 2, 4, 6, 8 in the right bank. The firing order is a common one, for example, 2 l 8 7 3 6 5 4 2 etc., wherein I treat cylinder No. 2 as the firing cylinder in all cases except during engine shutoff as described in connection with FIG. 2.

The injection, ignition, and attainment of peak combustion pressure transpire rapidly in any cylinder firing, all occurring in the course of a total, for example, of 22 of crankshaft rotation.

The engine for these illustrative purposes has a compact low inertia design, is capable of operation over a wide range of speeds and loads wherein the no-load idle speed may be on the order of one-eighth the maximum speed, and has direct injection. A four-stroke cycle is employed and, for that reason, the gear coupling referred to interposes a [:2 gear reduction between the driving crankshaft of the engine and the pump input drive 27. Thus, in properly timed relation to crankshaft rotation, the present device is operable to pump one metered quantity of fuel to each cylinder during every two revolutions of the crankshaft.

4 PLUS 4 CYLINDER EXAMPLE FIGS. 3, 4, 5, 6,

In these figures, the mechanical function of the metering port 26 is to follow counterclockwise motion relative to the metering sleeve bore as viewed in FIGS. 3 and 4, and top-to-bottom motion relative to the bore of the sleeve 50 in FIG. 5. The hydraulic function of metering port 26 in FIG. 5 is to have relative left to right axial motion to the sleeve bore in an initial manner so as to be covered, and in a continuing manner to increase duration of injection and hence pump more fuel to the engine. The hydraulic function of the designated governor or metering sleeve 50 in its motion relative to the metering port 26 is axially left to right in FIG. 7 initially to cover the metering port and subsequently to increase duration of injection and hence to pump more fuel to the engine cylinders.

With particular reference to FIG. 3, the right-hand helix spill grooves are identified there and elsewhere by their general reference numeral 60, whereas individual identifying

numerals

60a, 60b, 60c, 60d, and 602 used in FIGS. 4, 5, and 6 distinguish the grooves sequentially in their operation order.

Viewed mechanically, the difference in FIG. 5 be tween the metering port when in the position shown by the solid line 26 for following an indicated four cyls. idle circular path about the bore, and the metering port when in the broken line position for following the indicated full power circular path about the bore of the sleeve is that four cylinders are joined by four more active cylinders only when needed, and otherwise they are not joined by the latter four cylinders. In the full power path just referred to, the metering port 26 encounters a succession of control edges 106 of the spill grooves all inclined at the same single angle to the sleeve bore axis, not shown. In terms of the direction of advance of the port 26, the port has a late opening intersection in the late opening full power path and the significance is that the injection duration is delayed in its termination to provide maximum fuel flow at full load.

In contrast to alternating ones of the control edges which are milled uniformly from end-to-end with the single angle as shown at 106, each remaining one of the control edges provided on the spill grooves has a double angle control edge where the second angle edge is shown at 108. Thus, each remaining one of the control edges has for a major part one angle which ultimately diverges into a greater angle 108 to the sleeve bore axis, not shown, so that the corresponding four cylinders will receive no fuel when the metering port has the relative mechanical position shown by full line 26 in the four cyls. idle path. And yet the metering sleeve in the idle position as set by the governor causes the four cylinders firing at idle to receive more fuel than they would in an engine in which all cylinders operate at idle.

Therefore the engine does not die and, with respect to the firing cylinder (reference cyl. 2, as the starting point), the 1st cylinder next in rotation (cyl. 1, FIG. 5) has the effective pump stroke prematurely shortened to the point of zero injection duration, and it is the large angle edge 108 of groove 60b which causes it to be a non-firing cylinder. The second cylinder next in rotation (cyl. 8) is a firing cylinder, the third cylinder next in rotation is a non-firing cylinder, and so forth.

In FIG. 6, the greater angle edge 108 is cut in each remaining one of the spill slots by a rotary milling cutter, introduced in an intersecting left-hand helix path for a short distance at only one end of the control sleeve bore. The spill grooves 60 are otherwise all the same within the bore.

The transition in the initial cutting in and cutting out of operation of the four

cylinders

1, 4, 6, and 7 appears as a narrow crosshatched strip in FIGS. 5 and 7, and occupies a small portion of the speed range nearer the idle end than the full power end of the range. Thus during engine slowdown for instance, the double angle control edges reduce fuel to cylinders l, 4, 6, and 7 at a greater rate than the remaining four cylinders so that, at the time cylinders l, 4, 6, and 7 are completely cut out, the movement of the control sleeve is still within the control range of movement of the four spill grooves controlling those remaining four cylinders.

Nevertheless, the difference in magnitude between the second angle control edge 108 and the single angle control edge 106 is not enough to make the angle 108 appreciably large. Hence, the transition is essentially a gradual one without such abruptness as to cause engine surging or drastic fluctuations within the crosshatched strip of the speed range. This graduality is visually borne out from the appearance of the second angle as shown at 108 in FIG. and the diagonal portion of the flow-displacement curve as shown at 112 in FIG. 7 for cylinders l, 4, 6, and 7. For contrast, use the angle 106 as the basis of comparison in FIG. 5, and the portion 114 of the flow-displacement curve for

cylinders

2, 3, 5, and 8 as the basis of comparison in FIG. 7.

For brevitys sake, illustrated portions of the entire developed view of the grooved sleeve bore 50 are omitted from FIG. 5 because they are believed self-evident and self'explanatory, and written portions of a complete description of FIGS. 5 and 7 are omitted herefrom because they are believed self-evident.

Four active cylinders are not essential for satisfactory idle and two initial transitions, which can optionally be contiguous as provided, can cut out two pluralities of the cylinders and leave only two cylinders firing at idle. An example follows. I

2 PLUS 2 PLUS 4 CYLS. EXAMPLE FIG. 8

A grooved bore for the control sleeve 250 shown in this figure provides two contiguous narrow crosshatched paths encountered by the metering port, not shown, during engine slowdown. The groove 260a (as well as 260a) passed over by the metering port has only a first control angle edge 206, which is a single angle edge. A second control angle edge 208 in groove 2600 for the second cylinder next in rotation (cyl. 8, and also cyl. 5) causes the cylinder concerned to cut out of operation immediately before the engine reaches idle (engine idles on cyls. 2 and 3).

Theretofore, second and third control angle edges 209 and 210 in

spill grooves

260b and 260d will have caused the first and third cylinders next in rotation (cyls. l and 7, and also 6 and 4) to have cut out of operation. The angled edge 208 can be cut with a rotary milling cutter in a wide milling pass. Preferably however, the offset second and the doubly offset third

angled edges

209 and 210 are cut with a narrower rotary milling cutter introduced in overlapping and successive milling passes to minimize metal removal.

Two firing cylinders are not essential for satisfactory idle and several initial transitions, which can optionally be separated in speed, can cut out several pluralities of cylinders and the engine can have a one-cylinder idle. An example follows.

I PLUS 1 PLUS 2 PLUS 4 CYLS. EXAMPLE FIG.

In the initial transitions as the engine increases speed and power in the curves of this figure, it can be seen that in the one-cylinder idle portion 318 of the flowdisplacement curve the engine will idle on cylinder 2 drawing slightly more than mm /stroke of the pump. That is to say, the single cylinder (cyl. 2) will fire once for every two crankshaft revolutions. In the narrow crosshatched strip of transition containing the curve portion 316, cyl. 3 cuts into operation at a rate according to the portion 316 and at, for instance mm per stroke, each of cyls. 2 and 3 is receiving approximately 25mm fuel flow and the two cylinders are matched and firing at equally spaced apart intervals.

A slight speed increase ensues, after which another crosshatched transition occurs, represented by the narrow strip containing the portion 3 of another flowdisplaeement curve. Cyls. 5 and 8 are thus cut into operation at a rate according to the portion 314 and, at a fuel consumption of approximately 30mm per stroke, the four cyls. 2, 3, 5, and 8 are actively firing and are each being supplied the same with 30mm of fuel per stroke.

After a slight further increase in engine speed, the final transition represented by a crosshatched strip is encountered containing the portion 312 of the flowdisplacement curve for the remaining four cyls. l, 4, 6, and 7. At and above a fuel flow of, for instance 35mm per pump stroke, the eight cylinders are balanced with each receiving 35mm or more fuel per stroke of the pump.

The separation in speed between the several noncontiguous crosshatched transition strips is to provide further assurance against surging of the engine in the transitions. 1

For purposes of the example of FIG. 9, a single metering port such as the metering port 26 of FIG. 2 is all that is provided for metering. In other words, the only spill groove affording a finite duration of injection will be the late opening groove 60a which upon opening the metering port 26 perforce terminates injection with each firing of cyl. 2 during idle. The remaining cylinders will all have zero duration of injection and be nonfiring cylinders during engine idle.

However, a second metering port 426 which must be diametric to the first metering port 26 (FIG. 2) can be provided in thepump shaft 18 of all other examples of the device herein given. Similarly, a second timing port 428 diametric to the timing port 28 can be provided, and the reason is to meter more precisely with sharp cutoff of injection from the nozzles without dribble,

and equally sharp start of injection. Better control is known to be afforded on rate and quantity of fuel injected, when the nozzle operation is attended by quick opening and quick closing nozzle valve action.

In FIG. 2, devices made in production according to my invention can be made all the same except for substitutable metering sleeves 50. The engine in which such a device is installed will have either two cylinder idle or four cylinder idle. Such substitutable sleeves can further differ among themselves in the matter of where various pluralities of cylinders are to be cut in and cut out of operation in the speed range and whether transitions will be made contiguously or separated slightly from one another. Engine speed surges at the time, whether appreciable or barely perceptible, are nevertheless of no really objectionable amount.

If the devices in production are made with a single metering port 26, then the engine is afforded the fuller flexibility of a one cylinder idle, two cylinder idle, or four cylinder idle depending upon the metering sleeve 50 selected. The advantage is that only a single substitutable part is employed.

The result is a net reduction in the amount of fuel supplied during no-load idle operation compared to the prior art engines in which metering sleeves have hitherto caused them to idle on all cylinders. Moreover, the no-load idle in such prior art engines requires so little fuel for each of the cylinders that consistent injection of equal quantities of fuel to each cylinder can be difficult, and inadequate mixing of the fuel with slow moving swirl air results in poor combustion and comparatively low combustion chamber temperature, with a tendency toward erratic operation and excessive exhaust emissions.

Obviously, a multi-cylinder diesel engine which idles on one cylinder will display the best idling performance when subjected to comparison for its high thermal efficiency and high level of combustion chamber temperature. And one-cylinder idling has manifest advantage in the matter of reduced emissions when an engine, so operating, is being rapidly decelerated or is being motored by drive from the traction wheels during sustained downhill coasting, for example.

Variations within the spirit and scope of the invention described are equally comprehended by'the foregoing description.

What is claimed is:

l. A fuel injection pump for an engine having a number of cylinders and intended to idle on fewer than all of the number, said pump having a variable volume pump chamber portion whereof the pump chamber number is materially fewer than the number of engine cylinders and wherein the pump input drive produces pump strokes variable in effectiveness, a controlled sleeve having an individual spill duct for each of, and associated with each of, the engine cylinders and formed with a control edge inclined with respect to the sleeve axis, a pump shaft connected in the pump input drive, said pump shaft rotatably and slidably mounting said sleeve and presenting thereto a metering port in flow communication with the cylinders and with the variable volume pump chamber portion, the intersection of a control edge with the metering port determining the end of the effective pump stroke for each engine cylinder and thus the amount of the metered fuel charge pumped thereto, engine means for operating the pump shaft in timed relation to the operation of said engine cylinders, and slide means to slide the controlled sleeve for changing the control edge-metering port relationship and effective pump strokes of the pump chamber portion, said sleeve thus varying the metered charge to the individual cylinders, and having the control edge inclinations arranged so that some have greater inclination than others, whereby the charge to some cylinders decreases in like amount among themselves, but at a greater amount than in the others.

2. A fuel injection pump for an engine having a number of cylinders and intended to idle on fewer than all of the number, said pump having a variable volume pump chamber portion whereof the pump chamber number is materially fewer than the number of engine cylinders and wherein the pump input drive produces pump strokes variable in effectiveness, a controlled sleeve having an individual spill duct for each of, and associated with each of, the engine cylinders and fonned with a control edge inclined with respect to the sleeve axis, a pump shaft connected in the pump input drive, said pump shaft rotatably and slidably mounting said sleeve and presenting thereto a metering port in flow communication with the cylinders and with the variable volume pump chamber portion, the intersection of a control edge with the metering port determining the end of the effective pump stroke for each engine cylinder and thus the amount of the metered fuel charge pumped thereto, engine means for operating the pump shaft in timed relation to the operation of said engine cylinders, and slide means to slide the controlled sleeve for changing the control edge-metering port relationship and effective pump strokes of the pump chamber portion,'said sleeve thus varying the metered charge to the individual cylinders, and having the control edge inclinations arranged so that a parallety have greater inclination than others, whereby the charge to a plurality of said cylinders decreases in like amount among themselves, but at a greater amount than in the others, some of the just said plurality of control edge inclinations provided by first, second, and third edges on each spill duct, arranged offset from one another.

t t t

Claims

1. A fuel injection pump for an engine having a number of cylinders and intended to idle on fewer than all of the number, said pump having a variable volume pump chamber portion whereof the pump chamber number is materially fewer than the number of engine cylinders and wherein the pump input drive produces pump strokes variable in effectiveness, a controlled sleeve having an individual spill duct for each of, and associated with each of, the engine cylinders and formed with a control edge inclined with respect to the sleeve axis, a pump shaft connected in the pump input drive, said pump shaft rotatably and slidably mounting said sleeve and presenting thereto a metering port in flow communication with the cylinders and with the variable volume pump chamber portion, the intersection of a control edge with the metering port determining the end of the effective pump stroke for each engine cylinder and thus the amount of the metered fuel charge pumped thereto, engine means for operating the pump shaft in timed relation to the operation of said engine cylinders, and slide means to slide the controlled sleeve for changing the control edge-metering port relationship and effective pump strokes of the pump chamber portion, said sleeve thus varying the metered charge to the individual cylinders, and having the control edge inclinations arranged so that some have greater inclination than others, whereby the charge to some cylinders decreases in like amount among themselves, but at a greater amount than in the others.

2. A fuel injection pump for an engine having a number of cylinders and intended to idle on fewer than all of the number, said pump having a variable volume pump chamber portion whereof the pump chamber number is materially fewer than the number of engine cylinders and wherein the pump input drive produces pump strokes variable in effectiveness, a controlled sleeve having an individual spill duct for each of, and associated with each of, the enGine cylinders and formed with a control edge inclined with respect to the sleeve axis, a pump shaft connected in the pump input drive, said pump shaft rotatably and slidably mounting said sleeve and presenting thereto a metering port in flow communication with the cylinders and with the variable volume pump chamber portion, the intersection of a control edge with the metering port determining the end of the effective pump stroke for each engine cylinder and thus the amount of the metered fuel charge pumped thereto, engine means for operating the pump shaft in timed relation to the operation of said engine cylinders, and slide means to slide the controlled sleeve for changing the control edge-metering port relationship and effective pump strokes of the pump chamber portion, said sleeve thus varying the metered charge to the individual cylinders, and having the control edge inclinations arranged so that a parallety have greater inclination than others, whereby the charge to a plurality of said cylinders decreases in like amount among themselves, but at a greater amount than in the others, some of the just said plurality of control edge inclinations provided by first, second, and third edges on each spill duct, arranged offset from one another.