US3238934A - Liquid-fuel distributing means for internal combustion engines - Google Patents

Description

March 8, 1966 J. N. MORRIS ETAL 3,238,934

LIQUID-FUEL DISTRIBUTING MEANS FOR INTERNAL COMBUSTION ENGINES Filed March 24, 1964 2 Sheets-Sheet 1 IN VENTOR-S BERNARD FISHMAN GERALD BLOOM g aomgw; MORRIS March 8,' a. N. MQRRIS ETAL .9 9

LIQUID-FUEL DISTRIBUTING MEANS FOR INTERNAL COMBUSTION ENGINES Filed March 24, 1964 z shaets-sheez 2 BERNARD FlSHMAN GERALD BLOOM United States Patent 3,238,934 LIQUID-FUEL DISTRIBUTING MEANS FOR INTERNAL COMBUSTION ENGINES John Neville Morris, Birmingham, England, and Bernard Fishman, New York, and Gerald Bloom, Spring Valley, N.Y., assignors of one-half each to The S.U. Carburetter Co. Ltd, Birmingham, England, a British company, and Simmonds Precision Products, Inc., Tarrytown, N.Y., a corporation of New York Filed Mar. 24, 1964, Ser. No. 354,332 7 Claims. (Cl. 123-139) This invention relates to liquid-fuel metering pumps for supplying'a plurality of fuel-injection nozzles situated individually in the respective inlet ports or induction passages of a multi-cylinder, spark-ignition internal combustion engine. It is customary to provide such pumps either with separate metering chambers associated individually with each engine cylinder or with equivalent means, inherent in the pump, whereby equality of fuel distribution between all the fuel-injection nozzles is assured.

It is also known to provide a single outlet of metered fuel from the pump, and to effect distribution of this fuel via a common chamber from which leads a plurality of nozzle lines, each supplying an individual nozzle. A drawback of this last-mentioned arrangement, however, is that if the instantaneous rate of fuel output of the pump varies directly, or even appreciably, with its total output per unit of time-as clearly obtains, for instance, in the case of a continuous-flow positive displacement pump, or of an engine-driven plunger-type pump-then serious difficulties arise in providing a form of nozzle which will ensure both adequate pulverization of the fuel and equality of distribution throughout the full load and speed range of the engine.

In the caseof a fuel-injection nozzle provided with a fixed orifice, or a combination of fixed orifices, the instantaneous rate of fuel flow, when supplied by a pump having the characteristics presupposed above, will vary, as between the conditions of idling and full power output, in a ratio of the order of l to 50, and consequently the instantaneous pressure-drop across the nozzle will vary approximately as the square of this ratio. If, therefore, the minimum nozzle pressure-drop required to provide an acceptably finely divided nozzle spray is, say, p.s.i., then this pressure-drop, under full load and speed operation of the engine, will rise to an inconveniently high value, with consequent excessive loading of the pump and nozzle lines.

A known expedient for ameliorating the state of affairs just described is the provision of relatively large nozzle orifices which impose very low pressure-drops under idling and light running conditions, and, to ensure the required spray quality of the discharge under these conditions, the admission of atmospheric air to a pulverizing region downstream of the nozzles. This arrangement, however, is unsatisfactory because, under full-throttle operation, particularly at low speeds, the pressure within the inlet ports or induction passages of the engine is not appreciably below atmospheric, and thus the inflow of pulverizing air is much diminished with consequent deterioration of the quality of the spray.

Another known expedient for achieving equal distribution of the fuel between all the fuel-injection nozzles, when these are supplied by a pump having the characteristics presupposed, consists in the provision of expansibletype nozzles such as to permit of a wide variation in the instantaneous rate of fuel flow accompanied by a relatively small variation in nozzle pressure-drop. This type of nozzle is exemplified by one in which an outwardly opening pintle valve is held in spring-loaded contact with "ice a seating formed in the extremity of the nozzle body, the arrangement being such that a substantially constant pressure-drop is maintained across the valve seating for a Wide variation in the instantaneous rate of fuel flow, with a consequent acceptable pulverization of fuel.

Two practical difficulties beset this last-mentioned arrangement. Very delicate individual adjustment of the pintle valve loading springs is necessary in order to achieve equality of fuel distribution and, furthermore, owing to the relatively large peripheral length of the seating, very small valve lifts obtain, particularly at low engine speeds and loads, with a consequent liability for foreign particles of micronic dimensions to lodge between the valveand its seating, thus impairing both distribution and spray quality.

In a liquid-fuel metering and distributing system in accordance with the present invention, for a multi-cylinder,

spark-ignition, internal combustion engine, a plurality of fuel-injection nozzles of the fixed-orifice type, situated individually in the respective inlet ports or induction passages of the engine, is supplied by at least one common chamber which periodically receives a metered and pressurized charge of fuel from a shuttle-plunger pump having, in addition to a metered fuel reservoir, a pressurized fuel reservoir which, under the control of valve means, is abruptly volumetrically contractible by elastic means to effect rapid delivery of the charge from the metered fuel reservoir ,to the common chamber at an approximately constant pressure. In explanation of the significance of the above reference to at least one common chamber, it is desired to point out that the arrangement may either be such that all the injection nozzles are supplied simultaneously from one and the same common chamber (to which the fuel can be delivered by only a single duct); or, alternatively, it may be such that, instead of the single common chamber, there are two or more separate smaller chambers each common to, and supplying, its own group of the injection nozzles; these two chambers collectively being equivalent to employing a single larger chamber common to all the injection nozzles.

The difliculties associated with the expanding type of nozzle are avoided by the use of nozzles employing fixed orifices, and the difficulties commonly associated with this last-mentioned type of nozzle are overcome by employing -a pump having an appropriate delivery characteristic.

This characteristic, as has just been indicated, may be defined in terms of the rapidity with which a pressurized and metered quantity of fuel is made available for supply to the common chamber at the commencement of each delivery phase of the pump, together with the circumstance that an approximately constant pressure is active to impel this metered quantity of fuel into the common chamber and thence through the nozzle lines and nozzles.

It will be appreciated that the means whereby the above-mentioned volumetrically contractible pressurized fuel reservoir is placed in communication with the common chamber from which the nozzles are supplied, must be such that an extremely rapid rise of pressure within that chamber is assured, notwithstanding that the engine speed, and consequently the pump speed, may be very low; and that this pressure will be sustained at an approximately constant value throughout the discharge interval of the nozzles, thus ensuring, during this interval, an approximately constant pressure-drop across the fixed orifices of the nozzles which is of a value adequate to provide pulverization of their discharge notwithstanding that the nozzle orifices are sufficiently large to accommodate the fuel flow at maximum power conditions under the moderate and approximately constant pressure provided, and within the interval of time available for completion of the injection phase, even When the engine is operating at its maximum speed and load.

For the purpose of the invention any type of nozzle ing good fuel pulverization, may be employed. The swirlchamber type of nozzle is particularly suitable. In this type of nozzle fuel enters a small chamber through one or more tangentially disposed metering orifices, and emerges in a swirling state through a further metering orifice concentric with the chamber.

In a case of a fuel-injection system arranged to operate in accordance with the invention, the injection pulses directed into the inlet ports or induction passages of the engine occur simultaneously. Therefore, although such a pulse may be delivered into one or more'of the inlet ports or induction passages during the induction phase-of that port or ports, injection pulses, in the case of other ports or induction passages, will occur during phases of the engine cycle other than the induction phase. So long as a high degree of pulverization is provided by the nozzles, however, this asymmetry of phasing (as between the various engine cylinders) is known to have no significant effect upon engine operation, the only essential requirement being that at least one injection pulse must be supplied to each of the ports per engine cycle.

The details of the invention, as well as additional objects and advantages, will be clearly understood with reference to a preferred embodiment illustrated in the accompanying drawings employing similar reference numerals to identify the same elements in each of the several views, and in which: i

FIGURE 1 shows, in sectional elevation, a liquid-fuel metering pump, for use in carrying the invention into effect, together with some of its associated equipment;

FIGURE 2 is a similar illustration of a variant of the pump shown in FIGURE 1, having dual outlets each of which serves its own group of fuel-injection nozzles; and FIGURE 3 is a section on the line xx in FIGURE 2. The body of the metering pump 1 comprises a generally cylindrical housing 2 surmounted by a detachable cap 3, these two components having co-operating bolting flanges 4 and 5 respectively. The housing 2 contains a chamber 6 of annular :form, to which liquid fuel, drawn from a supply tank (not shown), is delivered through a pipe 7 by a positive-displacement extraneous pump 8 which has a delivery capacity in excess of the maximum demand of the engine being served. The chamber 6, which conveniently may be designated an expansible pressure accumulator, is elastically distensi'ble and contractible, being sealed at one end by a resilient spring-loaded diaphragm 9. This diaphragm, which may be made of neoprene or any other fuel-resistant elastomeric material, is clamped peripherallybetween the bolting flanges 4 and 5, and is loaded by a helical compression spring 10 that is trapped between an annular channel abutment 11 on the diaphragm and the top of the cap 3. At its opposite end the pressurized fuel reservoir 6 has an accurately flat internal facing '12 having two ports or metering chambers 13 and 14 which, by means of ducts 15 and 16 respectively, are in permanent communication with opposite ends of a cylindrical bore 17 that contains a closely fitting shuttle-plunger 18 of stainless steel or other non-corrodible material. The pressurized fuel reservoir 6 is, of course, safeguarded by a pressure-relief valve 19. This valve, which controls a relief duct 20 passing through the diaphragm 9, is set to permit a normal working pressure of about 150 p.s.i. in the pressurized fuel reservoir 6; fuel ejected from the relief outlet 21 being returned to the supply tank by way of a pipe (not shown).

An engine-driven ported valve 22 of the rotary disc type, having accurately flat faces, and to which an epicyclic motion is imparted continuously during operation of the pump, by means of a drive-shaft 23 and an eccentric 24, is disposed between the internal facing 12 of the pressurized fuel reservoir 6 and an equally accurate facing 25 on one end of a cylindrical metering block 26. The latter is spring-loaded axially so that the disc valve 22 isnipped between its co-operating stationary facings 12 and 25. The spring-loading of the block 26 is effected by a helical compression spring 27 trapped between the top of the cap 3 and an abutment flange 28 on a cylindrical block 29 that is coaxial with, and surmounts, the metering block 26. The central zone of the diaphragm 9 is clamped between the two blocks 26 and 29, which are secured together by a central bolt 30. The upper portion ofthe block 29 projects through an opening 3'1 in the cap 3.

Owing to the epicyclic motion of the disc valve 22, a lapping action takes place which minimizes any scoring of the rubbing surfaces that may arise and ensures the maintenance of an extremely accurate planar contact between those surfaces, with consequent avoidance of leakages at the ports controlled by this valve.

Each face of the disc valve 22 contains an annular groove, and these two grooves, 32 and 33 respectively, are in permanent communication with each other by way of a duct 34. The annular groove 33 co-operates with a port 35 in the facing 25 of the cylindrical block 26. From the port 35, and by way of a corresponding aperture in the diaphragm 9, a duct 36 in the block 29 affords communication with a single pipe 37 which leads into a chamber 38; this being the common chamber mentioned earlier, and from which individual lines, as at 39, lead'to the respective fuel-injection nozzles, as at 40, of the fixed-orifice, swirl-chamber type.

The arrangement is such that as soon as one of the two ports 13 or 14 in the internal facing of the pressurized fuel reservoir 6 begins to become uncovered by the moving rim of the epicyclic valve 22, pressurized fuel (sustained by the elastic contractibility of its reservoir 6) rushes through that port and abrutly impels the shuttleplunger '18 until this is arrested by a stroke-limiting stop. As depicted in the drawing, the port 13 has become uncovered by the valve 22, whereas this valve has cut off communication between the pressurized fuel reservoir 6 and the port 14; the latter now being open to the annular groove 32 in the valve 22. Consequently, the shuttle-plunger 18 is being impelled from right to left, by pressurized fuel flowing through the duct 15, and is in process of delivering a metered quantity of fuel ('by Way of the duct 16, the port 14 and so on) to the common chamber 38, and thence to all of the injection nozzles simultaneously.

Upon termination of the delivery phase, the shuttleplunger- 18 is impellcdback to its initial position against an adjustable stop 41, due to the continued movement of the epicyclic valve 22 causing a reversal of the fiow of pressurized fuel through the ports 13 and 14. That is to say, the common chamber 38 receives a metered quantity of fuel at every stroke of the shuttle-plunger 18. The displacement volume of the latter constitutes a metered fuel reservoir. The adjustable stop 41 determines the quantity of fuel metered per stroke of the shuttle-plunger 18, and is adjustable by a cam 42 and associated control mechanism (not shown) that forms no part of the invention.

In the embodiment of the invention illustrated in FIG- URE 2, the design of the metering pump 1A is such that, by way of dual outlets 43 and 44, and their associated pipes 45 and 46 respectively, the shuttle-plunger 18 is enabled to supply alternating pulsations of pressurized and metered fuel to two independent sub-common chambers 47 and 48, each of which supplies half the total number of engine cylinders. This arrangement results in the frequency of discharge of the fuel-injection nozzles, as at 40, being halved (so that each cylinder receives one injection per cycle instead of two) and, at the same time, the quantity of fuel discharged from each nozzle per injection is doubled, with beneficial effects upon the flow equalization afforded by the fixed-orifice characteristic of the nozzles, as well as improved fuel break-up.

It should perhaps be mentioned here that, as it is unnecessary to repeat the description of the arrangement and functioning of the various parts common to the two systems, those parts of FIGURES 2 and 3 which remain the same as in FIGURE 1 are identified by the same reference numerals; and the suflix A is employed to indicate a modification of the part similarly numbered in FIG- URE 1.

Referring now to FIGURES 2 and 3, the disc valve 22A (which replaces the corresponding valve 22 of FIGURE 1) has peripheral gear teeth 49 which mesh with a similar set of teeth 50 formed on a stationary annulus 51 which, as depicted, is integral and concentric with the cylindrical housing 2A. The valve 22A also has a number of pairs of ports 52 and 53 on its lower and upper surfaces respectively, each of such pairs being interconnected by a duct 54. If the numbers of gear teeth 49 and 50 provided on the valve disc 22A and housing 2A respectively, are such that the valve disc performs 1/n of a revolution upon its own axis for each revolution of the driveshaft 23 and eccentric 24, then the number of pairs of ports 52 and 53 provided is made equal to n. In the particular example illustrated, the ratio of the numbers of teeth 50 and 49 is 9 to 8 and, consequently, the valve disc 22A will rotate by one-eighth of a revolution for each revolution of the drive-shaft 23. Therefore, eight pairs of the ports 52 and 53 are provided, one of these pairs of ports coming, in sequence, into co-operation with each of the single pair of oppositely placed stationary ports 35 and 55, and 14, 13, provided in the facings 25 and 12 respectively, on each rotation of the drive'shaft 23.

From the ports 35 and 55, and by way of corresponding apertures in the diaphragm 9, ducts 36 and 56 in the block 29A lead to the respective outlets 43 and 44. The arrangement is such that as soon as one of the two ports 13 or 14 in the internal facing 12 of the pressurized fuel reservoir 6 begins to become uncovered by the moving rim of the valve 22A, pressurized fuel (sustained by the elastic contractibility of its reservoir 6) rushes through that port and abruptly impels the shuttle plunger 13 until this is arrested by a stroke-limiting stop. Simultaneously, or somewhat prior to the uncovering of the port 13, the port 14 has been placed placed, via one of the pair of ports 52 and 53 and their interconnecting duct 54, in communication with the port 35 and its continuation duct 36 and thence, via the pipe 45, with the sub-common chamber 47. The fuel received by this chamber is discharged simultaneously by the associated group of three injection nozzles 40.

As the result of a further half-revolution of the driveshaft 23 from the situation as depicted, all the communica tions just described become reversed. Consequently, the moving rim of the valve 22A now admits pressurized fuel from the fuel reservoir 6 to the duct 14, and the shuttleplunger 18 is impelled in the opposite direction to that just described, the duct 13 being simultaneously, or somewhat in advance, placed, by one of the pairs of ports 52 and 53 and their interconnecting duct 54, in communication with the port 55 and its continuation duct 56 and thence, via the pipe 46, with the sub-common chamber 48. The fuel received by this chamber is discharged simultaneously by the associated group of three injection nozzles 40.

A further half-revolution of the drive-shaft 23 results in restoration of the situation depicted in FIGURE 2 and, therefore, in a further injection by the group of nozzles 40 served by the sub-common chamber 47. It will be appreciated that in the interval between the two injection phases described (i.e., alternating between delivery via the sub-common chambers 47 and 48), the ports 52 and 53 will have rotated, with respect to the centre line of the valve 22A, by one-sixteenth of a revolution only, and will thus be somewhat out of relative register with the pair of ports 14 and 35 and the pair 13 and 55, with which they alternately establish communication. Their effectiveness in establishing the required communication, both in the position depicted in FIGURE 2 and in the position resulting from half a revolution of the drive-shaft 23 therefrom is, however, ensured either by making them of circular formation as shown, but of adequate diameter, or by making them of arcuate configuration.

Although there has been shown what is considered to be a preferred embodiment of the invention, it will be evident that many changes and modifications can be made without departing from the essential spirit of the invention.

It is intended, therefore, in the annexed claims, to cover all such changes and modifications as fall within the scope of the invention.

We claim:

1. In a fuel injection pump for an internal combustion engine the combination comprising a casing having a liquid-fuel inlet port communicating with an expansible pressure accumulator chamber, a ported valve mounted within the casing for rotary motion and formed with seating faces on opposite sides thereof, a metering block including at least two outlet ports mounted for movement within the casing and having one surface adjacent to one seating face of said valve and shaped complementally thereto, a flanged cap superposed on said metering block, means defining openings therein in coincidence with the ports in said block and a diaphragm interposed between said flange cap and said block, said valve being disposed between said block and one end of the casing with its other seating face in contact with said end of the casing, resilient means disposed within said casing for urging said metering block toward one end of the casing to maintain intimate contact between the casing, the valve and the metering block, plural metering chambers in said casing having one end opening adjacent to the seating face of said valve with the other ends of said chambers communicating with a bore, a plunger in said bore, means for imparting motion to said ported valve, the valve being adapted to connect two of the metering chambers in said casing alternately to said fuel inlet port and the outlet port associated with another chamber and means connected to the accumulator chamber for causing the plunger to reciprocate whereby a metered quantity of liquid is alternately received in said metering chambers and expelled through the discharge port into said other chamber.

2. In a fuel injection pump for an internal combustion engine as claimed in claim 1, wherein another resilient means is concentrically disposed about said first resilient means and interposed between said casing and said diaphragm.

3. In a fuel injection pump for an internal combustion engine as claimed in claim 2, wherein an abutment is positioned on said diaphragm and adapted to receive the force applied by said other resilient means.

4. In a fuel injection pump for an internal combustion engine as claimed in claim 1, wherein said flanged cap projects through said casing.

5. In a fuel injection pump for an internal combustion engine as claimed in claim 1, wherein means are provided for integrating said flanged cap to said metering block.

6. In a fuel injection pump for an internal combustion engine as claimed in claim 1, wherein one of said means defining an opening in said flanged cap is adapted to support a pressure relief valve.

7. In a fuel injection pump for an internal combustion engine as claimed in claim 1, wherein two of said outlet ports in said metering block are adapted to supply fuel to plural chambers.

References Cited by the Examiner UNITED STATES PATENTS 2,892,453 6/1959 Stoll 123-13917 3,124,116 3/1964 Morris 123139 MARK NEWMAN, Primary Examiner.

KARL J. ALBRECHT, Examiner.

L. M. GOODRIDGE, Assistant Examiner.

Claims (1)

1. IN A FUEL INJECTION PUMP FOR AN INTERNAL COMBUSTION ENGINE THE COMBINATION COMPRISING A CASING HAVING A LIQUID-FUEL INLET PORT COMMUNICATING WITH AN EXPANSIBLE PRESSURE ACCUMULATOR CHAMBER, A PORTED VALVE MOUNTED WITHIN THE CASING FOR ROTARY MOTION AND FORMED WITH SEATING FACES ON OPPOSITE SIDES THEREOF, A METERING BLOCK INCLUDING AT LEAST TWO OUTLET PORTS MOUNTED FOR MOVEMENT WITHIN THE CASING AND HAVING ONE SURFACE ADJACENT TO ONE SEATING FACE OF SAID VALVE AND SHAPED COMPLEMENTALLY THERETO, A FLANGED CAP SUPERPOSED ON SAID METERING BLOCK, MEANS DEFINING OPENINGS THEREIN IN COINCIDENCE WITH THE PORTS IN SAID BLOCK AND A DIAPHRAGM INTERPOSED BETWEEN SAID FLANGE CAP AND SAID BLOCK, SAID VALVE BEING DISPOSED BETWEEN SAID BLOCK AND ONE END OF THE CASING WITH ITS OTHER SEATING FACE IN CONTACT WITH SAID END OF THE CASING, RESILIENT MEANS DISPOSED WITHIN SAID CASING FOR URGING SAID METERING BLOCK TOWARD ONE END OF THE CASING TO MAINTAIN INTIMATE CONTACT BETWEEN THE CASING, THE VALVE AND THE METERING BLOCK, PLURAL METERING CHAMBERS IN SAID CASING HAVING ONE END OPENING ADJACENT TO THE SEATING FACES OF SAID VALVE WITH THE OTHER ENDS OF SAID CHAMBERS COMMUNICATING WITH A BORE, A PLUNGER IN SAID BORE, MEANS FOR IMPARTING MOTION TO SAID PORTED VALVE, THE VALVE BEING ADAPTED TO CONNECT TWO OF THE METERING CHAMBERS IN SAID CASING ALTERNATELY TO SAID FUEL INLET PORT AND OUTLET PORT ASSOCIATED WITH ANOTHER CHAMBER AND MEANS CONNECTED TO THE ACCUMULATOR CHAMBER FOR CAUSING THE PLUNGER TO RECIPROCATE WHEREBY A METERED QUANTITY OF LIQUID IS ALTERNATELY RECEIVED IN SAID METERING CHAMBERS AND EXPELLED THROUGH THE DISCHARGE PORT INTO SAID OTHER CHAMBER.

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