US2531202A - Fuel injection pump - Google Patents

Description

Nw. 21, 195o D. J. DESCHAMPS FUEL INJECTION Pun? 4 Sheets-Sheet 1 Filed may 4,1945

lNvl-:N-ron JEJIREJ. aise/AMPS Q BY P f sm q fl Has/ATTORNEYS Nov. 21 1.950

Filed may 4, 1945 Nov.' 2l, 1950 D. J. DESCHAMPS FUEL INJEc'rIoN Puur 4 Sheets-Sheet 3 Filed May 4, 1945 H I5 ATTORNEYS Nov. 2l, 1950 D. J. DESCHAMPS FUEL INJECTION mp 4 Sheets-Sheet Filed nay 4, 1945 INVENTOR OEIS/R517. EJL'HA MP5 BY SMM- www XM H l5 ATTORNEYS geteilten et. at, te ,53H02 UNITED STATES PATENT OFFICE FUEL INJECTION PUMP pegue J. Deschamps, nutherfnra, N. .1.,assignuit to Deschamps Fuel Injection Corporation,

Rutherford, N. J., a corporation of New York Application my L1, 1945, semi No. 591,914

z claims. (ci. s-11s) This invention relates to 'fuel injection pumps for internal combustion engines. The object of the invention is to provide an improved pump for injecting liquid fuel into the cylinders. particularly of aircraft engines.

The steadily increasing size and speed oi' airplanes requires engines of greater power output. It is not practical to obtain the necessary power by increasing the number of engines as it is not desirable to use more than four. or perhaps six, engines on a single airplane. The use of contrarotating propellers enables the power of a single engine unit to be increased to about 4000 H. P. The amount of power which can be obtained, however, from a single cylinder is limited to about 150 H. P. Consequently', the only present method -available for obtaining the desired power per engine unit is by the use of large numbers of cylinders, and engines of 14, 16, 18, 24, 28, 36, and even 42, cylinders are now being considered.

With the pump construction heretofore proposed it is impracticable from the standpoint of manufacture to make fuel injection pumps having more than about fourteen plungers, and it is preferable to reduce this number. A 36-cylinder engine would require three 12plunger pumps, or four 9-plunger pumps. It is diillcult, however, to find room on the engine for installing, and for providing driving connections, for such a number of pumps in addition to the present accessories for which mounting pads and drive gearing have to be provided. It not only complicates the mechanical problem but appreciably increases the weight of the engine. The added gears and bearings increase the opportunity for defective operation and tend to complicate servicing.

The aim of the present invention is to overcome such dimculties in a large measure, reducing the number of pumps and pump drives required for large engines, thereby simplifying the engine arrangement including the mounting and driving of the pumps and the linkages for controlling their outputs and reducing the engine weight.

More speciflcally,'the invention aims to double the number of cylinders of a fuel injection pump without substantially increasing the weight and space requirements of the plunger-actuating mechanism.

Another object of the invention is to provide a fuel injection pump structure which is accessible` fuel injection pump structure in which vibration is reduced to a minimum.

A further object of the invention is to provide a vfuel injection pump construction which undesirable stresses in the plunger-actuating mechanism are substantially eleminated.

A still further object of the invention is to provide a fuel injection pump construction in which the wear of the various parts during ordinary operation is reduced to such an extent as to give the pump exceptionally long life. l

In fuel injection pumps of this kind it is important to arrange the output control mechanism in such a way that the output of each cylinder can be adjusted independently of every other cylinder. It is an object of this invention to provide adjustable output control mechanism in which the possibility of these parts being put out of proper adjustment by ordinary wear is reduced to a marked extent.

'I'he invention will be understood by an examination Vof the accompanying drawings which, by way of example, illustrate the invention as embodied in a 16-cylinder pump, and also from a consideration of the following detailed description thereof. In these drawings;

Fig. l is a view showing the pump in approximately horizontal central longitudinal section,

the section being taken on the broken line I-I of Fig. 3;

Fig. 2 is an end view of the pump looking from the right-'hand end as shown in Fig. 1, with the fuel tubing connections removed;

Fig. 3 is a transverse vertical central section taken on the broken line 3 3 of Fig. 1;

Fig. 4 is an outside bottom view of the pump;

Fig. 5 is a view of the pump in rear elevation;

Fig. 6 is a longitudinal section of the output control member of one of the pumping units;

Fig. 7 is a transverse section taken on line 1--1 of Fig. 6;

Fig. 8 is a side view of a part shown in Fig. 6; Fig. 9 is a section taken on line 9-0 of Fig. 8; and

Fig. 10 is a detail of a part shown in Fig. 7.

Referring now to these drawings, the pump comprises three principal sections, a central or drive housing I and two end housings or pump heads 2 and Il. The central housing l is provided with a mounting flange 4 having suitably arranged holes for receiving mounting bolts by which the pump may be secured on an appropriate mounting pad provided on the engine.

Central housing l is a generallv cylindrical vstructure having a thick walled bottom Vor end Y 3 heavy plate B having about the same thickness v as end' wall 5. The-end housings 2 and 3 are alike and each is in the form of 'a hollow cup or cap. The right-hand end housing 2 is mounted on a ange 'I at the right-hand end of central housing I. It is removably held yagainst this flange in fluid-tight relation by a series of screws 8.

Left-hand end housing 3 is mounted in fluidtight relation against the outer surface of end plate 6 which in turn is fixed in fluid-tight relation against a second flange 9 on central housing I. These parts are removably held in position by a series of screws I which pass through openings in flange 9 and plate Band are tapped into a suitable flange on end housing 3.

The two end housings 2 and V3 each have end walls II and IIa respectively, containing a circular row of apertures in which are mounted pumping units I2 and I2a respectively. In the embodiment illustrated there are eight of these pumping units of identical construction in each of the end housings. Each of -the pumping units comprises a cylinder or bushing I3, a plunger I4, a tappet mechanism indicated generally `by numeral I5, and an output control member or part controlling sleeve indicated generally by numeral I6.

Tappet mechanisms I-I5a include helical springs I1- I1a which actuate the plungers I4- I4a on their intake strokes, and slippers I8- I8a. These are held in operative engagement, by means of springs I1 and IIa, with the opposite faces I9 and I 9a of an actuating element shown in the embodiment illustrated as a duplex wedge-shaped wobble plate structure indicated generally by numeral 20.

This structure includes two members 2I and 2Ia which are keyed to a rotary drive shaft 22, and between these there is a driving gear 23 which is shown as being made integral with shaft 22. Members 2I and 2Ia are fixed on shaft 22 with their inner sides in permanent engagement with the faces of gear 23, and with their faces I9 and I9a at equal and opposite angles to the shaft. as shown in Fig. l.

Meshing with gear 23 is an idler gear 24 which is journaled on a shaft 25 mounted adjacent the face of mounting flange 4 and parallel to drive shaft 22. The outer side ofidler gear 24 projects beyond the face of flange 4 to operatively engage an operating gear (not shown), provided on the engine, when the pump is mounted on the engine mounting pad.

Considering a single pair of pumping units I2 and I2a, each complete rotation of the wobble plate causes the tappets I5, I5a, and plungers I4, Ila tobe actuated simultaneously through a complete pumping cycle. The tappets are forced outwardly (causing the plungers to make their delivery strokes) by the action of faces I9 and I9a of wobble plate 20 on slippers I8 and I8a, and the plungers and tappets are moved inwardly on the intake strokes by means of springs I'I and I1a which maintain the slippers in contact with faces I9 and I9a respectively. During a single revolution of drive shaft 22 each of the eight pairs of pumping units I2 and I2a is operated through such a complete cycle.

It will be understood that the phase relationship of the two wobble plates numbers 2| and 2Ia and the location of the center lines of the pumping units I2 and I2a of each pair of pump cylinders to each other may be varied depending upon the type of engine on which the pump is 4' to be used. With certain multi-cylinder twocycle engines, in order to provide the proper timing of the injection of the liquid fuel into the various cylinders of the engine, it is necessary to have the pumping units I2 and I 2a of each pair located on the same center line exactly opposite each other, and to have the wobble plate members 2| and 2 la de-phased from one another exactly as shown in the embodiment of the invention illustrated in the drawings. In'this case, the thrust loads on the wobble plate structuredue to the hydraulic load on the plungers from the two opposite groups cancel out, so that bearings 2B and 26a are not subjected to any thrust load and carry only a very light radial load making'it possible to use small light weight ball bearings.

With certain other types of multi-cylinder engines, such, for example, as the V, "W, "H, "X radial, barrel, etc., having their cylinder banks arranged at diierent angles with respect to one another, in order to provide proper timing and sequence of the injection, the center lines of the pumping units I2 and I2a must be offset somewhat (or the wobble plate members 2| and 2Ia disposed in the wobble plate structure 20 at somewhat less, or somewhat more, than 180 out of phase from one another). and the amount of this offset may, in some instances, place the center lines ofpumping units I2a substantially intermediate the center lines of pumping units I2.

Evenv in this extreme situation, however, the bending moment applied to shaft 22 by the wobble plate structure 20 is so small that it may be disregarded, with the consequence that shaft 22 need be neither very large in diameter nor very long; and therefore it may still be supported in comparatively light ball bearings such as those shown at 26 and 26a. These bearings, moreover, may be carried in the ends of hollow cylindrical sleeves 21 and 21a, which are mounted with a force fit in central apertures in end wall 5 and plate 6 respectively. Sleeves 21-21a are provided with shoulders 28 to properly position them in these apertures.

In either of the above-mentioned arrangements of the wobble plate members 2| and 2Ia, that is to say, whether these members are dephased exactly 180 so that the keys by which they are secured to drive shaft 22 are exactly in alignment, or whether members 2I and 2Ia are de-phased somewhat, less, or more, than 180 so that the keys are shifted somewhat out of alignment, the wobble plate structure 20 as a whole may still be referred to as a wedge-shaped structure because the amount of change in the phase angle is small.

One of the tappet mechanisms I5 is shown in section at the lower right-hand portion of Fig. 1. It may be understood from this view that these tappet mechanisms are composite structures comprising a thimble-like sleeve 29 within which is held a push rod 30. This structure is described in detail in the copending application of Desire J. Deschamps and Douglas C. Clarke, Serial No. 503,470, filed September 23, 1943, which matured into Patent No. 2,519,893 on August 22, 1950, assigned to the same assignee as this application.

Briefly, however, the arrangement is such that at the right-hand end of the tappet mechanism a positive coupling is made with a knob 3| on the end of plunger I4, and slipper I8 at the left-hand end of the tappet mechanism is mounted in al Semi-spherical socket formed in the end of push rod 39 and held in this socket by means of a retaining plug' 32 which is pinned in the hollow end of push rod 30 and is associated with slipper I3A in such a way as to allow the slipper freedom of movement in its socket.

Helical spring I1 maintains all the parts in constant engagement with one another in such a way that the coupling with knob 3| of the plunger is without lost motion and slipper I5 is constantly maintained in contact with the surface of wobble plate 20. During the reciprocation of the tappet mechanism, sleeve 29 slides in a bush-lng 33 which is driven into a suitable aperture in the end wall 5 of housing I. It wil be understood that there is a circular row of these apertures in end wall 5 to correspond with the apertures in the head of end housing 2 for the pump cylinders I3; also that at the opposite end of the pump the arrangement is similar, the circular row of tappet mechanism bushings 33a being mounted in apertures in plate 5,

'I'he interior of central housing I constitutes a chamber for collecting the lubricating oill which is used to lubricate tappet mechanisms I5 and I5aas is about to be described, and the interiors of each of the end housings 2 and 3 constitute intake reservoirs for the liquid fuel which is to be" pumped, as will be described presently. The detalls of the lubrication system are also set forth in the prior application above referred to.

The oil flows from a distributing groove 34 in the surface of cylindrical sleeve 21 through a passage 35 in end wall 5 and a'passage 36 in bushing 33 to the surface of plunger tappet sleeve 29 which it lubricates by means of the circular groove shown in this sleeve. At one point during each reciprocation ofthe tappet mechanism passage 91 will register with this groove and permit the oil to flow to the hollow interior of push rod 35 from whence it passes through a groove (not shown) in plug 32 to lubricate the exterior socket surface of slipper I9. It alsoV passes through the slipper and forms an oil cushion between it and the wobble plate. The lubricating oil is supplied to the pump under pressure from the lubricating system of the engine, with which a connection is made by means of a duct 39 (Fig. 5) which termlnates in the surface of mounting ilange 4. The

inner end of duct 39 communicates with two branch ducts 39 and 39a. Duct 39 communicates with an inwardly directed drilled passageway 45 adlacent flange 1. the outer end of which is closed with a plug and whose inner end delivers the oil to distributing groove 34. Duct 39a terminates at the fece of flange 9 where it communicates with a short duct 4I in plate 5. Duct 4I .loins a drilled passageway 42, the outer end of which is closed with a plug and the inner end of which delivers oil to distributing groove 34a.

'Ihe lubricating oil from the sleeves and slippers of the tappet mechanisms collects in housing I and draws back into the engine through the opening in mounting ilange 4 shown in Fig. 5.

It will be understood that each of the pump cylinders or bushings I3 and I3a is connected with one of the engine cylinders by means of a metal tubing not shown) which is appropriately connected with delivery connection 43 or 43a for the particular pump cylinderl Delivery connection 43 is threaded into the outer end of the pump cylinder aperture and serves to clamp a valve seat member 44 and the flange of cylinder' I3 against a shoulder 45 at the bottom of this aperture. Valve seat member 44 has a central delivery opening 46 through which the fuel is expelled during the working stroke of pump plunger I4. this opening being closed by means of an outlet valve 41 which is longitudinally slidable within a sleeve formed on member 44 andbiased against the valve seat surrounding delivery opening by means of a helical spring 43.

The outer ends of delivery connections 43 and 43a are internally threaded and may receive hollow screws 49 by means of which banjo iittlngs 59 are appropriately mounted against the outer ends of the delivery connections 43 and 43a; The ends of the tubing which connects with the engine cylinders are brazed or soldered into these banJo fittings 50.

The fuel, such vas gasoline, is delivered to the pump through a supply opening 5I (Figs. 3 and 4) and flows through apertures 52 into the interior of a metal iilter mounting 53 and thence into the interior of a tubular filter element 54 which is closed at its outer end. After passing through thewalls of filter element 54 the fuel collects in filter element housing 55 which is formed on the top of central housing I.

The fuel then flows through longitudinal passageways 55 and- 59a, shown in dotted lines in Fig. 5 and which terminate in the faces of flanges 1 and 9 respectively of central housing I.

A passageway 51 in end housing 2 conveys the fuel from passage 55 into the interior of the end xhousing 2 which, as before stated, constitutes a fuel inlet reservoir. A hole 59 through plate 5 at the opposite end of central housing I conveys the fuel from passage 55a to a passage 59 formed in end housing 3 which delivers fuel into the interior of the fuel reservoir within this housing.

A vapor outlet is provided in the top of filter housing by means of which the fuel vapor released in the pump may be returned to the fuel system.

Filter element 54 is attached to filter mounting 53 in such a way that the filter element may be readily removed and replaced. For this purpose the open end of illter element 54 is clamped against a ange on mounting 53 by means of a rod 5I passing centrally through both the lter element and mounting 53, one end of this rod being threaded into the cap portion of mounting 53 and its opposite end passing through an aperture in the end of filter element 54 and on which a suitable nut and washer may be placed to hold the parts together.

Filter mounting 53 is provided with a flange 52 which forces a soft rubber gasket 63 against an annular shoulder 64 formed on the interior of illter element housing 55. When mounting 53 is fixed in place on the outer end of housing 55 by means of the screws 55 the soft gasket is compressed both to form a fluid-tight joint with shoulder 64 and to perrrit a gasket 66 to be clamped in fluid-tight relation against the end oi housing 55. l

The inlet of the liquid being pumped to the pumping units I2 and I2a, and the control of the output will now be described. This mechanism is described in considerable detail in the above mentioned copcndng apclication, and it will be described only briefly here. In the pump illustrated in the drawings, the arrangement of the output control members I6 and Ilia and the fuel inlet passages in plungcrs I4 and I4a is such that the ending of the injection periods is fixed, the amount of fuel injected being regulated by varying the beginning'of the injection period.

The cylinder chambers of cylinders I3 and I3a are indicated by numerals 61 and 51a and are at the outer ends of-plungers I4 and He. Plunger I4 shown at the lower right in Fig. 1 is at the extreme end of its intake stroke, ready to commence a delivery stroke, while plunger I4 of the pumping unit at the upper right of this figure is at the end of its delivery stroke.

The fuel to be pumped is supplied to the interiors of end housings 2 and 8 by means of the usual transfer pump which delivers it under a pressure of about fifteen pounds per square inch. Consequently, the inlet reservoirs are at all times completely filled with fuel. The fuel therefore flows into the cylinder chambers 81 and 61a when the passages provided in plungers I4 and I4a are opened.

These passages consist of an linlet opening 88 which communicates with an axial passage 68, and a relief opening also a relief port 1I in the walls of cylinder I3. Output control member I8 is slidable axially on plunger I4 and its position regulates the amount of fuel injected into the engine cylinder by the stroke of plunger I4.

Referring to the pumping unit I2 shown at the lower right-hand portion of Fig. 1, cylinder chamber 61 has been filled with fuel which has flowed into it through passages 68, 10 and 89. On the first part of its working or delivery stroke fuel is expelled from the cylinder chamber through inlet opening 68 and relief opening 10 into the interior of the inlet chamber within housing 2. However, when the edge of opening 18 passes the end of cylinder I8 and the edge of opening 68 passes the left-hand or control edge of control member I6, the fuel remaining in the cylinder chamber is trapped and forced through outlet valve openings 46 into the tubing which connects this pumping unit with one of the engine cylinders. Injection continues until relief opening 1I! registers withA relief port 1I, at which instant the pressure in cylinder chamber 81 is relieved.

It will be understood that if desired the inlet and relief openings 10 may be changed in their positions so as to provide for a fixed beginning of the injection period, the ending of the injection period being determined by the position of control member I6 to regulate the amount of fuel injected. The details of such rearrangement of the plunger ports are described in the copending application above mentioned.

The shifting of control members I8 and I6a to regulate the amount of fuel injected is accomplished by means of control disks 'I2 and 12a. These are mounted on plunger members 13, 13a which are telescoped within the outer ends of supporting sleeves 21 and 21a to slide longitudinally of these sleeves. The outer edges of disks 12 and 12a engage grooves 14 in output control elements I8 so as to cause al1 of these elements to move simultaneously with the movement of the disks.

The disks are biased outwardly by means of helical springs 15 and 15a and are moved inwardy ly by cams 16, 18a, which are fixed to vertical shafts 11, 11a. These shafts are suitably journaled in the respective end housings 2 and 3 and their outer ends project outside of these housings at the bottom and have actuating arms 18 and 18a secured to them as shown in Fig. 4. These arms are connected to operate in unison by means of a rod 19, and actuating arm 18 has an extension 80 to which a link from a mixture control apparatus, or other suitable control mechanism, is connected. Arm 18 may also be provided with a pointer 8l moving over a fixed scale 82 to indicate the output setting of the pump in degrees o angular movement, or otherwise.

Referring now to Figs. 6 to 10 inclusive. there is here illustrated an improved construction of output control member I8. This member comprises a sleeve 8l which is threaded into an outer body member 84 in which the annular groove 14 is cut. Adjustment of the output on individual pumping units is obtained by rotating sleeve 88 in body 84 which shifts the control edge of sleeve 88 'with respect to body 84 and hence with respect to control disk 12.

In order to lock sleeve 88 in adjusted position a snap ring 8l having an inwardly projecting tongue 88 encircles body 84, tongue 88 projecting through any one of a series of apertures 81 and engaging any one of a series of slots 88 provided in sleeve 88. As the number of these apertures and slots differs a precise adjustment may be obtained.

Experience with this type of output control vmember has shown that unless the screw threads of sleeve 88 and body member 84 fit each other without clearance, the rapid reciprocating motion of the plunger, which causes a slight drag in the bore of the sleeve, causes any play or looseness which may originally exist to increase rapidly. Since a few thousandths of an inch wear in the fit between these threads may cause a substantial change in the amount of fuel delivered by such pumping unit, it is important to prevent the development of even a small amount of wear.

To this end a corrugated spring 89 is placed between the head on sleeve 83 in which slots 88 are cut and a shoulder 9U which is provided on body member 84. The compression range of this spring is sufiicient to provide for the required lengthwise shift of the control edge of sleeve 83 with respect to body 84 for adjustment purposes, and at the same time prevents all movement between the inter-fitting threads between those members, even though the threads are originally cut with a considerable clearance between them.

Because of the arrangement of the two operating faces I9 and I9a of the wobble plate 2li at equal and opposite angles to one another with respect to drive shaft 22, thereby providing an actuating element for the tappet mechanisms I5 and I5a, which is substantially wedge-shaped in side view. and also because the arrangement of two circular rows of pumping units on opposite sides of this actuating element, the rotation of this element causes the tappet mechanisms I5 and I5a and ytheir connecting pump plungers I4 and I4a to be forced apart by a wedging action. The result is that the stress produced in the structure of actuating element 20 is almost entirely a compressural stress.

Such a stress can be withstood by a comparatively light weight structure and, moreover, only a light weight and short drive shaft 22 is required. As may be seen in Fig. 1 the drive shaft 22 and its supporting bearings 26 occupy so little space that they may be received within the circle of the rows of pumping units I2 and I2a, and consequently do not increase the length of the pump. The length of the pump is determined principally by the dimensions of the pump parts, and the driving mechanism is a small factor.

While only one embodiment of the invention has been disclosed it will be understood that the construction of the pump can be changed considerably without departing from the spirit of the invention. I have already indicated one change which may be made, namely, in arranging the output control mechanism of the pumping units so as to provide for a fixed beginning of the injection period rather than a fixed ending As another example of a change which might be made is that instead of using a rotating wobble plate, as shown at 20 (which, however, provides the most compact construction), a rotating hub type wobble plate may be used, such as is disclosed in the copending application above referred to and in which the rim of the wobble plate rotates very slowly if at all. Also use can l housing, said pumping Aunits having their axes be made of a face cam having two opposed faces. v

In addition, in the embodiment shownthe wobble plate structure 20 is rotated by means of spur gearing. but it will be understood that other driving means may be employed if desired, such, for example, as bevel, helical or worm gearing.

It will be understood that these and other changes in the pump construction may be made within the scope of the invention which is set forth in the appended claims.

I claim:

- 1. In a fuel injection pump, an elongated cylindrical housing having an aperture in one side thereof, a rotary drive shaft supported substantially centrally and coaxially thereof, an actuating element disposed on said shaft comprising a spur gear structure of less diameter than said housing and having on its opposite sides two opposed actuating faces permanently fixed at equal and opposite angles to the axis of said shaft, a plurality of cylinder and plunger pumping units having their axes parallel with said drive shaft and each having a spring to actuate the plunger on the intake stroke, said units being disposed in pairs. the units of each pair being' located on opposite sides of said actuating element and beyond the ends of said drive shaft, their plungers being held in operative engagement respectively with said opposed actuating faces by said springs, and driving means extending through said aperture and disposed in operative engagement with said gear. Y

parallel with one another and disposed longitudinally of the housing and the unitsof each group being arranged in pairs in axial alignment with one another and the plungers of one group being arranged to face the plungers of thel other and disposed in spaced relation to one another, an actuating element for said plungers disposed in said spaceand comprising a spur gear structure of less diameter than said housing and similar wobble plates engaging said plungers disposed on the opposite sides of said gear and in symmetrical'relation to the central transverse plane of the gear. a shaft for said gear and wabble plate structure disposed between and centrally of said groups of pumping units, a driving pinion meshing with said gear and projecting through said aperture in the mounting pad beyond the surface thereof. and a shaft for supporting said pinion.

DESIRE J. DESCHAMPS.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PA'I'ENTs

Images