US1931543A

US1931543A - Fuel pump

Info

Publication number: US1931543A
Application number: US475791A
Authority: US
Inventors: Carl F High
Original assignee: Individual
Current assignee: Individual
Priority date: 1930-08-16
Filing date: 1930-08-16
Publication date: 1933-10-24
Anticipated expiration: 1950-10-24

Description

0 6L 24, 1933. HIGH 1,931,543

FUEL PUMP Filed Aug. 16. 1930 3 Sheets-Sheet 1 m1 a I w g Oct. 24, 1933. c. F. HIGH 1,931,543

FUEL PUMP Filed Aug. 1 1950 1 3 Sheets-Sheet $8 I00 a w fi f7 AZFHJ' .77 aZ/ Patented Oct. 24, 1933 UNITED STATES PATENT OFFICE F EL PUMP Carl F. High, Madison, Wis. 1 Application August 16, 1930. Serial No. 415,791

' 7 Claims. (01. 103-40) This invention pertains to fuel pumps, and more particularly to a fuel pump capable of use in connection with all types of conventional internal combustion engines. I

Heretofore, in pressure fuel pumps numerous and serious objections have been encountered in several respects, namely: metering the-fuel; proper lubrication of the operating parts; compactness and lightness of weight; and mechanical design. 1

It is, therefore, the primary object of the present invention to provide a comparativelysimple, compact, and inexpensive device of exceedingly light weight and efiicient operation with respect to both fuel injection and lubrication.

Incidental to the foregoining, a more specific object of the invention is to provide a pressure fuel pump in which provision is made for definitely and exactly metering the fuel supply to an 20 exceedingly fine degree.

A further object is to provide a fuel pump, in-

eluding a plurality of pump units with means for insuring uniform distribution to each pump.

Another object is toprovide means for automatically controlling the fuel charge in predetermined relation to the load, either through variation of the air 'or fuel.

In connection with lubrication of the pump units, a more specific object resides in the provision of a structure in which the lubricant is positively fed to the engaging surfaces of the pump, and the pressure below the head of the plunger never exceeds the pressure above.

With the above and other objects in View, which will appear as'the description proceeds, the invention resides 1n the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the herein disclosed invention may be made as come within the scope of the claims.

In the accompanying drawings is illustrated one complete example of the physical embodiment of the present invention constructed ac cording to the best mode so far devised for the practical application of the principles thereof.

In the drawings, Figure 1 is a vertical section through a fuel pump constructed in accordance with one form of the present invention;

Figure 2 is a longitudinal section upon an exaggerated scale of the preferred structure of fuel injection nozzle to be utilized in connection with thepump;

Figure 3 is a transverse section through the discharged end of the nozzle, the same being taken on the line 33 of Figure 2;

Figure 4 is a transverse section taken on the line 4-4 of Figure 1;

Figure 5 is a top plan view with parts broken 0 away and in section taken on the line 5--5 of Figure 1; c

Figure 6 is a vertical section through a pump constructed in accordance with the preferred form of the present invention;

Figure 7 is a detailed section taken on the line 7-7 of Figure 6;"

Figure 8 is a detailed section illustrating the preferred structure of fuel cylinder and pump;

Figure 9 is a detailed section of a governor actuated mechanism for regulating the fuel sup- Referring nowcmore particularly to the ac- 'companying drawings in which like numerals represent likeparts, and more especially to that form of the invention illustrated in Figures l to 4, the numeral 1 designates a pump casing, which is preferably annular in shape and has arranged at spaced intervals adjacent the periphery a plurality of vertical bores 2, so which communicate with the annular recesses 3 formed in the lower part of the casing. A can 4'bolted or otherwise secured to the bottom of the casing forms a closure for the recess 3.

Mounted within each of the bores 2 is a bush- 5 ing 5 which constitutes a fuel cylinder having slidably mounted therein a piston 6.

Centrally journalled within the pump housing 1 is a cam shaft 7, the upper end of which is mounted in an antifrictional bearing 8, while the lower end is journalled in the anti-frictional bearing 9 carried by the cap 4. A suitable gear or pinion 10, secured to the protruding end of the cam shaft, serves to effect a driving connection with any suitable part of 5 the motor, whereby in operation the annular cam 11, carried by the cam shaft, serves to actuate the plungers, as hereinafter described. The lower extremity of each plunger 6 is provided with a reduced shank 12, which is straddled by a bifurcated ear 13 carried by a crosshead 14. A head 12', formed on the end of thev reduced shank 12, serves to secure the pump piston 6 to the cross-head.

As best shown in Figure 4, the cross head.14 is provided with flanged edges 15, which travel in grooved ways 16 secured to the inner wall of the housing 1 in any suitable manner, such as by riveting or the like. Each cross-head 14 carries a pair of vertically spaced studs 14', upon which are mounted the rollers 14', which engage the upper and lower faces of the annular cam 11.

Obviously, as the cam shaft and cam 11 are rotated vertical reciprocative movement will be imparted to the cross-head 14, which in turn effects reciprocative action of the piston 6 within the cylinder 5, whereby the fuel is drawn into the cylinder and injected into the motor, as will be hereinafter described in further detail.

In that form of the invention illustrated in Figures 1 and 6, the cylinder bores 2 are pro vided with shoulders 17 upon which the enlarged heads 18 of the bushings are seated. Intermediate the shoulder 1'7 and the lower end of the cylinder bushings 5, the outer diameter of each bushing is restricted to form an annular oil space around the bushing, which space communicates with the interior of the cylinder adjacent its lower end through the radial openings 19, whereby the engaging surfaces of the cylinder piston are lubricated, as will be hereinafter described.

The lower end of the cylinder 5 provides a snug fit within the bore 2, and in addition thereto a packing ring 20 may be utilized to form a tight connection to prevent oil from draining from the oil space surrounding the bushing.

As shown in Figures 1 and 6, the pistons 6 are provided with a plurality of vertically spaced annular grooves 21, the upper surfaces of which are either tapered or rounded outwardly toward the outer periphery of the piston, while the lower edge forms a sharp angle, whereby in the upward movement of the piston, oil fed into the cylinder will be picked up by the lower edge of the groove and carried upwardly the distance of the piston. stroke. Obviously, on the down stroke of the piston, due to the top tapered surface of the groove 21, a thin film will remain upon the wall of the cylinder at the point to which it has been previously raised.

From the foregoing description it will be readily seen that oil fed into the lower portion of the cylinder through the radial openings 19 will be picked up by the lowermost groove 21 and carried up the cylinder the height of the piston stroke, which is approximately the distance between the oil grooves 21. Each successive stroke of the piston will carry the oil higher within the cylinder, thus ellectively lubricating the cylinder through the entire length of its bore.

Figure 6 illustrates a preferred form of cylinder bushing 5, having slidably mounted therein a pump piston 6' similar to the piston 6, except with respect to the oil grooves. The bushing 5' is adapted to be seated upon the shoulder bore oi the housing 1, and intermediate the shoulder and the lower end of the bushing is an annular flange 130 slidably fitting the restricted portion of the bore to eliminate leakage of oil from the space surrounding the bushing between the flange and shoulder. Just above the flange 130, the bushing is provided with radial ports 131 through which oil is fed to the interior of the cylinder, where it is picked up by the top groove 132 and carried upwardly to lubricate that portion of the cylinder bore between the ports 131 and the inlet port 241'.

In the foregoing preferred structure, the radial ports 131 are elevated in the bushing to a point closely adjacent the oil ,duct 54, where the top oil groove 132, having a sharp lower edge and a tapered upper surface, picks up oil at the bottom of its stroke and carries the same upwardly within the cylinder to the extremity of its stroke, which is slightly below the fuel intake port. The lower groove 133 is provided with a sharp upper edge and a tapered lower surface, whereby on the downward stroke, oil is fed down in the cylinder. Obviously, with the sharp edges of the groove carrying the oil away from the radial ports 131, and the tapered edges spreading the oil toward the wall oithe cylinder, the latter is efiectively lubricated both above and below the ports substantially double the distance of the normal stroke of the piston.

In the various forms of cylinder bushings illustrated, it will be noted that they are provided with an interior annular groove 19 positioned below and closely adjacent the fuel intake ports of the cylinders. This groove serves as an oil reservoir receiving its oil supply from the top groove in the piston which, on its upward stroke, by-passes the same. The oil in the annular groove 19 lubricates the tip of the piston as it passes on each down-stroke, and on its upstroke. The tip of the piston carries oil from the groove to the wall of the cylinder above the intake port. The groove 19 also prevents fuel, which might possibly leak past the tip of the plunger, from leaking below the groove, in asmuch as the pressure in the groove is increased, because of the necessary pressure required to cause leaking of the fuel. Therefore, any leakage from the groove would tend to be upwardly past the short distance between the groove and intaize port rather than down the much greater distance to the oil intake openings or the bottom oi the cylinder.

it will, thereiore, be seen that the groove makes possible piston. lubrication at a pressure less than the downward pressure of the fuel on the piston, with no leakage or washing of oil film oil the piston or cylinder wall below the groove.

In that form of the invention illustrated in Figures 1 and 4., the large head of the cylinder bushing 5- is provided with an annular groove 22, which registers with the tangential ducts or passages 23. Thus, as fuel is fed through the ducts 23, as will be hereinafter explained, the same entirely surrounds the groove 22, which communicates with the interior of the cylinder through the tangential openings 24. Thus, as the piston 6 travels upwardly and displaces fuel prior to closing the inlets 2 1, the expelled fluid will be rotated within the annular groove, and as a portion of the fluid endeavors to return through one of the tangential ducts 23, extending in the direction of rotation of the fluid, the same will be replaced by fluid through the opposite duct, thus insuring a full supply surrounding the inlet ports 24 at all times, regardless of the method of metering.

As shown in Figure 1, the cylinder bushing 5 is held upon the shoulder 1'7 by means of a threaded head 25, which engages the packing ring 26. that serves to prevent leakage of fuel past the threads of the head.

The head 25 is provided with an annular bore 25', closed at its top by a threaded plug 27 and having its lower end terminating in a tapered seat 28 for reception of the valve 29. It will be noted that the valve 29 is provided with a recess for reception of a spring 30, which normally serves to hold the valve upon the tapered seat 28. It will be noted that the lower end of the valve 29 is restricted to provide a surrounding angular ports 32. Thus, as the piston 6 is forced upwardly within the cylinder, the fuel contained therein will lift the valve and thentravel through the ports 32, resulting in an injection action to evacuate fiuid within the well. Ohviously, as the valve seats to cut of! further supply, the evacuated area within the well will cause fluid above the valve to be drawn into the well, thus preventing dripping at the discharge end of the ejection nozzle, and insuring an immediate cut-off of fuel.

The head 25 is provided with a threaded port 32' in which is connected in any conventional .manner, a fuel line or pipe, not shown, which line in turn is connected with a fuel injection nozzle 33, such as shown in Figure 2, although it will be understood that any other type of nozzle may be utilized, without affecting the operating of the invention.

Taking up the fuel supply and metering, the housing 1 has provided in its upper end a central recess 34, to which fuel is supplied through the inlet port 35 that in turn is connected withany su'itable'sourceot fuel supply.

Extending upwardly within the recess 34 is a boss 36 surrounded by a screen 37 and having its upper end reduced and spaced from the screen. A cap 38', threaded into therecess 34 forms a closure therefor, and also serves to retain the screen 37 in place upon the boss 36.

The boss 36 is provided with a central bore in which is slidably mounted a sleeve valve 38 having a central well 40 and an outlet 41 communicating with said well. As best shown in Figures 1 and 4, the outlet 41 is of crescent shape formed by milling through the side of -the valve with a bafile tool. Obviously, because of this shape, as the valve is depressed to expose the port 41 below the central bore of the boss 36, the opening will be gradual, thus controlling the proportion and volume of fuel admitted to the distributing compartment 42 formed below the boss 36.

Obviously, from the foregoing, as fuel enters the recess 34 through the port 35, the same will surround the screen 37, and after passing through the same to remove coarse impurities, the fuel will fill the well 40 within the valve 38, from which it is discharged to the distributing compartment 46, it being noted that the fuel must pass through the screen 3'7, inasmuch as the cap 33' forms a cover to prevent fuel from passing overthe top of the screen.

Mounted within thecentral fuel distributing compartment 46, is a distributor head 4'1, the top of which is inclined upwardly towards the axis of the head, and provided with a plurality of annular grooves 48. It will be readily seen that as fuel is discharged into the distributing compartment, the annular grooves 48 will cause the same to be evenly distributed aroundthe head, thus insuring a uniform supply of fuel to all of the ducts 23, which communicate with the cylinders 5. 1

The center of the head 47 is provided with a vertical bore for slidable reception ofthe lower end of the valve 38, whichin turn is recessed to receive a coiled spring 49 normally urging the valve to closed position.

Below the head 47 is positioned in annular screen within which is disposed a series of filter pads 51, which serve to filter oil through an inletport 52 from any suitable gravity or pressure lubricant supply. The screen 50 and pads 51 are positioned between a pair of retaining discs 51', the upper disc being provided with a central opening 51". Obviously, as the lubrieating oil passes through the screen 50 and the pads 51, the same will pass through the open-- ing 51"-into the interior of the distributor head 47, which, adjacent its lower edge, is provided with radial ports 53 that communicate with the oil ducts 54, which, in turn, communicate with the oil spaces surrounding the cylinder bushings 5. Thus, it will'be seen that oil fed to the pump cylinders also serves to lubricate themetering valve 38 journalled within the central bore of the distributor head 47.

The actuating mechanism contained within the lower portion of the housing 1, as well as the lower bearing 9, receives its lubrication from oil discharged through a vertical duct 55 forming a communication between the oil inlet port 52 and the lower compartment.

Also, a portion of the oil passing through the filter screen and the filter pad may be fed to the antifrictional bearing through an opening 51",

formed in the lower plate 51. It will thus be;

seen that all moving parts are completely housed and thoroughly lubricated from a single source of supply.

For the purpose of exactly and minutely governing or metering the fuel supply of the various pump cylinders, the valve 38 is controlled by a metering pin 56, slidably journalled within the cap 38', and having its lower end engaged in a seat formed in the bottom of the well 41. A packing 57 and gland nut 58 serve to prevent leakage of fuel past'the metering pin. In order to effect actuation of the metering pin 56, several types of mechanism may be employed, but the present description will be confined to that structure disclosed in Figure 1, wherein a bracket 59 is suitably mounted upon the top of the cap 38, and "has pivotally secured thereon a double cam lever 60, the operation of which is manually controlled.

As best shown in Figure 1, the lower end of the cam lever 60 is provided with an arcuate cam 63, the working face of which is inclined at an angle to a horizontal plane, and engages the within boss 36 to vary exposure of the valve port 41.

Referring to the structure illustrated in Figures 6 and '1 of the'drawings, which is the preferred form of the present invention, while the general principle of operation is similar to that obtained in the structure heretofore described, the same diifers materially in various structural features, primarily in the manner of introducing and metering the fuel.

, In this form of the invention, the fuel supply is introduced into a concentric head 83 threaded, into the top of the housing, the"cap being provided with inlet and

outlet ports

84 and 84, respectively, the inlet port being connected-with any suitable source of fuel supply, while'the outlet port is provided with any suitable connection for venting and preventing vapor lock.

From the port 84, the fuel passes downwardly through the duct 95 into a distributing chainher so. Mounted wit the distributing cham= her is a shouldered sleeve 9?, the lower end or which is fitted in a central bore 99 provided in the housing 1 and counicating with the distributing chamber. The upper end or the sleeve 99', projecting into the distributing chamber, is perforated, and surrounded by a filter cloth or screen 99, which is secured in position upon the top of the sleeve 97 by clamping engagement of the head 83.

In this form of the invention the tangential ducts 23, heretofore described, are eliminated, and the single radial ducts 23' are provided, which ducts register with radial ports 99 formed in the sleeve 99. I

From the foregoing, it will be readily seen that fuel introduced into the ports 99 will pass into the distributing chamber 99, thence th ough the filtering screen 99 and the perforated upper portion of the sleeve 97 to surround the plug valve 91, slidably mounted within the sleeve.

Aside from the method oi metering, the plug 91 is actuated similar to the valve to, through the metering pin 59, which is actuated by the cam or carried by the cam lever 69.

Regulation oi the fuel supply distributed through the ports 99 is obtained means of the conical or tapered head 92 of the plug 91, which, as the plug is vertically actuated by means of the metering pin to and the opposed spring i9, will etlect gradual opening or closing or the ports 99.

Another distinction residing in ti o preferred form of the invention, is the method of packing or sealing the connection between the fuel discharge head 25 and the cylinder bushing 5. As shown in Figure 6, the peripheral lower edge oi the head 25 is chainiered or bevelled oil, thus providing an annular space between the head and cylinder bushing, which is triangular in cross section. Prior to threading the head 25 into the casing, a ring of soft metallic material, such as solder wire or the hire, and of less area cross section than the cross section area of the annular space between the head and cylinder bushing, is positioned on top of the cylinder bushing. Obviousl upon turning the head down upon the packing ring 93, the latter will be compressed to conform to the shape of the annular space between the head and bushing, which, being triangular in cross section, will provide a secure, three point contact between the bushing ring 93 and the triangular races or the annular space between the head and bush- It will also be noted that in this form of the invention, the annular groove 22, provided in the bushing 5, as illustrated in Figure .1, is elimi nated, and a single inlet port 24 is provided, which communicates with the radial duct 23' and is of the same diameter or cross sectional area, the advantages of which will be later described more in detail.

In the preferred form oi the invention under consideration, the method of lubrication remains the same as that described in connection with the structure shown in Figure l, and therefore needs no further explanation. Also, the manner of actuating the pistons 6 remains the same, as well as the structure of the fuel discharge head 25 and the valve 29.

While the present invention may be utilized to advantage with various types of structures of fuel injection nozzles, a preferred form is illustratcd in Figure 2, wherein the nozzle '33 is provided with a central bore 94 reduced intermediate its ends to form a shoulder 95. The upper end or the bore 94. is threaded to receive a conventional fuel connection communicating with the discharge 32, as heretofore explained, while that portion of the bore adjacent the shoulder 95 is threaded to receive a head 96, which head carries a pin 97 of smaller diameter than the restricted portion of the bore.

The head 96 is provided with annularly spaced ports 98 communicating with the space surrounding the pin 97 and positioned within the bore above the head 96 is a filter screen 99. Obviously, as fuel is forced into thenozzle from the discharge head 25, the same will pass through the screen 99 and the ports 98 into the restricted portion of the bore 94.

The bore 9 1 terminates in a tapered seat 100 for reception of a discharge disc 101 provided in its upper face with a central annular pocket 192 having divergent and tangential grooves 103 extending therefrom to the periphery of the disc.

As indicated in Figures 1 and 2, the pocket 192 is of less diameter than the end of the pin 9?, which serves to secure the disc upon its seat, and therefore fuel forced through the restricted portion of the bore surrounding the pin 9'! will enter the tangential grooves 93 and thence flow into the annular pocket 102, resulting in a swirling of the fuel within the pocket from which it is discharged through the orifrees lot in a fine whirling spray which would materially facilitate thorough vaporization of the fuel as the same is injected into the air supply or cylinder of the motor.

structure illustrated in Figure 9 provides for gulation of the fuel charge through automatic control of the fuel supply by means of type of conventional governor. In this structure, a bracket 11? is mounted either on the cap 98' or the head 83, and has sliclably mounted therein a block 119, which engages the metering pin to. Opposed to the block 118 is a stationary blocl: 119, adjustably mounted within the bracket 117 and regulated by means of the threaded stud 129.

The bracket 117 is provided with a central vertical slot 121, in which are mounted rollers 122 carried by the blocks118 and 119, respectively, which rollers engage the opposite faces oi an elongated cam or wedge 123 projecting through the slot 121 and connected in any suitable manner to a mechanical governor, which also actuates the throttle in the air manifold.

It will be apparent that as the com 123 is reciprocated longitudinally, the lower block 118 will be actuated to operate the metering pin 56 to vary metering of the fuel supply.

General resume of the structure and operation In the design of a fuel pump as illustrated at minimum speed or tipped from a horizontal plane, as must frequently occur in aircraft, vehicle, and other engines.

From the distributing chamber 46, the fuelfinds free passage through the ducts 23 to the annular grooves 22 surrounding the cylinder bushings 5, from which it enters the intake ports communicating with the interior of the cylinder as said ports are opened on the suction stroke of the pump piston 6. r

The amount of fuel taken into the cylinder on each operation of the piston is determined by the average differential pressure of, the interior of the pump cylinder and of the fuel surrounding the same. In other words, the fuel inducted through the ports will vary with the amount of fuel and with the degree of average pressure on the fuel outside of the cylinder as compared with the average low pressure or degree of total evacuation within the cylinder. The amount of fuel, as well as the degree of average pressure surrounding the ports is regulated by the setting of the metering valve port 41, and is greater than absolute vacuum only because of the constant evaporation of fuel remaining between the top of the piston 6 and the discharge head 25 after each stroke.

In the structure under consideration, lubrication of the metering valve 38 and the pump unit is provided for by taking oil from any source of pressure or gravity supply through the inlet port 52 and strainer or filter 50, from, which it passes into the recessed distributing head 47 to the metering valve and through the ports 53 to the ducts 54 to surround the cylinderbushing 5. From this space, the oil passes 'through the inlet ports 19 adjacent the lower end of the bushing, where it is carried upwardly within the cylinder by the initial pressure and the action of the piston which, because of the contour of the grooves 21, carries the oil upwardly upon the sharp lower edge of the groove, allowing the same to. adhere to the cylinder wall as the upper surface of the groove compresses the film against the cylinder wall and passes over the film on the downward stroke of the piston.

Some of the oil progressively fed upwardly into the cylinder is discharged above the piston,

thus lubricating the valve 29- and the wall of the cylinder above the inlet ports as the piston moves above the same on its upward stroke.

This method of piston lubrication, in which the average pressure of oil up the piston is less than the average pressure of fuel down the piston, is feasible only because the pressure from the tip of the piston down is relieved through the inlet ports and equalized with the pressure of the fuel surrounding the ports, thus preventing any possibility ofretarding the upward feed of oil within the cylinders. I

As heretofore explained, the general principle of operation of both forms of the invention illustrated is identical, the distinction residing only in structural and operative details. In Figure 6, the fuel, instead of/being supplied to a distributing chamber through the housing 1, is fed into a concentric cap mounted upon the head of the housing. From the fuel intake port 84, fuel flows downwardly through the duct 95 into the fuel chamber as, from which it passes through the screen or strainer 89 and thence through the perforated upper end of the distributor sleeve 87 to surround the plug 92. It will be seen that the flow of fuel is unretarded, inasmuch as the perforated'end of the sleeve 87 provides a large entrance passage, thus insuring an ample supply of fuel within the sleeve surrounding the plug adjacent the outlet ports 90 in the sleeve, the fuel being of constant pressure under all possible conditions.

The metering plug 91 is ground and lapped to fit the bore of the sleeve and is urged by the spring 49 into engagement with the metering pin 56, which extends through the packing gland in the head 83, its upper end being operatively engaged by the cam face 63 formed on the cam lever 60. The metering of the fuel is thus obtained by the axial movement of the metering pin, the cam forcing it downwardly to ex- .pose the ports 90 and the spring 49 returning it.

Actual metering of the fuel occurs when the v conical surface of the metering pin exposes the ports 90, which results in uniform distribution of fuel to the various pump cylinders through the ports and ducts heretofore described, uniform metering being assured inasmuch as the conical surface is machined true to the cylindrical surface of the plug and by the outlet ports 90 being formed of uniform size; their upper edges terminating in the same transverse plane.

From the outlet port 90, the fuel is drawn through the ducts 23 into the several pump cylinders, as their intake ports are progressively uncovered upon actuation of the pistons.

It is at the metering valve outlet ports and in the communicating ducts and ports to the pump cylinders that the characteristics of a volatile fuel metered into vacuum become evident.

It has been found, after a series of tests, that a volatile fuel follows a definite mode of expansion, in which, as the liquid is drawn by vacuum through the inlet or inlets of the pump cylinder, there is a formation at the inlet ports of a series of gas pockets or bubbles formed by the flashing into vapor of the more volatile fractions. It may be stated that these bubbles would collect in a dome outside of the inlet ports, Whereas were the fuel to remain in liquid form, the same would seek a level below the inlet ports, were one obtainable. Such structure would rapidly result in pumping the fuel'chamber dry, then forcing gas only from the dome outside the ports until such time as the fuel chamber again fills suinciently to prime the piston.

A definitely capillary attraction or surface attraction causes the pump to draw the liquid from below the port level until the attraction is finally broken when'it persists in pumping gas from the dome until the fuel chamber has filled up to or above the port level.

The present structure clearly overcomes the foregoing objections in that no depression or dome is formed in the fuel supply passages below or above the cylinder intake ports to collect either liquid or gas bubbles.

In the present invention, as metering begins, small pin bubbles are formed at the outlet ports 90 upon opening of the same, which bubbles are carried through the communicating passages by the liquid fuel to the pump cylinders. As the outlet ports 90 are further restricted, larger bubbles are formed, which are also carried into the pump cylinder. v

At extreme throttling, there are mostly bubbles, and irrespective of the degree of metering,

these bubbles expand or multiply so as to always fill the passages and pump cylinders. Consequently, metering is a functioning of the hubble liquid ratio, or in other words of the wetness or dryness of what may be termed the fuel-suds.

A very advantageous feature of this condition of fuel is the factthat it may be drawn up as readily as it is drawn down, there being no perceptible change upon the meter, should theplane of the fuel chamber or the various passages depart from a horizontal, even when held at the maximum angle of degrees. The reason for this resides in the fact that the fuel converted into bubbles or gas is naturally lighter than liquid and therefore has a tendency to rise, while the liquid portion is heavier and flows down more readily, each assisting the other, depending on the direction of flow. Also, the vacuum produced within the cylinder communicating with the passages and chamber, serves to lift the vaporized fuel to a much greater height than necessary, in the present structure.

Pa ticular attention is directed to the advan of the novel construction of the discharge is and the valves 29, which are designed to give minimum clearance above the piston, and same time to relieve pressure in the fuel lin prevent drooling at the tip of the aton ring or injector nozzle. This is accomplished .ving a lap fit between the upper part of valve and the bore, thus causing the fuel forced past the conical seat to surround the lower restricted portion of the valve, and pass through. the angular ports 32 communicating l the central well.

fuel thus forced through these ports creates an ejector action upon the fuel in the well, through the velocity of flow, causing the well. to be evacuated as long as the flow continues. When the pump piston reaches the limit of its stroke, and the flow of fuel is discontinued, the valve 29 immediately seats, causing a portion of fuel surrounding the restricted portion of the valve to pass into the ports in valve.

Further, as the valve seats and the flow is cut off, pressure in the fuel line is released, as the evacuated well in the valve is again filled. It might be said that the foregoing action causes a minute momentary suction at the discharge outlet of the nozzle, which momentarily draws the fuel back to efiectively prevent drooling or dripping.

Particular attention is directed to the simplicity and compactness of design. of the fuel pump, wherein the pump units are concentrically spaced around a central common fuel distributing chamber requiring a single unitary metering valve, yet insuring a uniform supply to each pump unit, regardless of tilting of the fuel pump; also the radial arrangement of the pump unit allows a common actuating means, such as the rotary cam illustrated.

The cross-heads, which actuate the piston, engage the cam disc with rollers above and below, and are reciprocated in ways, which are provided by securing the grooved guides in the finished bore of the housing. The curved outer surfaces of all of the cross-heads and all of the guides,-

are accurately machined by clamping the required number of units in a jig and machining them to the correct diameter of the recessed bore of the housing, shims being utilized berecipes tween the ways and cross-heads to provide the desired clearance.

In addition to the foregoing, a common source of lubrication is provided, which insures uniform supply to each pump unit, in addition to complete lubrication of all actuated parts.

I claim: I

1. A fuel pump comprising a housing provided with a distributing chamber, a pump unit mounted in said housing and communicating with said distributing chamber, means within said housing for actuating said pump unit, means for metering the fuel in said fuel distributing chamber, and a discharge valve unit for said pump unit comprising a head threaded into said casing, and provided with a central passage in communication with the discharge side of said pump and provided with a valve seat at its lower end, a spring-urged valve normally engaging said seat and slidably mounted within said passage and provided with a central well and inclined radial openings forming a communication between the upper portion of said well and the periphery of said valve, whereby fluid from said pump is forced through said ports to evacuate said well 10p when the valve is raised from its seat.

2. A fuel pump comprising a housing provided with a fuel distributing chamber, means for metering fuel in chamber, a pump cylinder mounted within said housing and having an annular groove surrounding the same and tangential inlet ports communicating with said groove, said housing having spaced ducts tangential to said groove and forming a communication between said fuel distributing chamber and said groove, a pump piston adapted to reciprocate in said cylinder, and means for reciprocating said piston.

3. A fuel pump comprising a housing, a fuel distributing shell mounted in said housing, a

cap secured on said housing and provided with a fuel inlet communicating with said distributor shell, said distributor shell being provided with radial outlet ports, a plurality of pump units disposed in said housing concentrically of said shell and having communication with the outlet ports in said shell, and a valve plug slidable in said shell and provided with a conical surface to gradually expose said outlet ports upon depression of said valve plug.

4. A fuel pump comprising a housing provided with a recess and a restricted bore communicating therewith, a shoulder distributing shell positioned in said bore and projecting into said recess, its upper end being provided with open ings disposed concentrically about said shell in said recess, a cap threaded into said recess and provided with a fuel inlet port communicating with said recess, a plurality of pump units having communication with said distributing shell through ducts formed in said housing, said ducts being of uniform area in cross section and positioned upon the same horizontal plane, and a metering valve controlling the supply of fuel to said ducts, said valve comprising a plug slidably mounted in said shell and provided with a conical peripheral face to efiect opening of said ducts and secure a uniform supply of fuel to each duct.

5. A pump unit for fuel pumps comprising a cylinder provided with an inlet port adjacent 1 its upper end, a lubricating port intermediate said fuel port and the lower end of said cylinder, the inner wall of said cylinder being provided with an annular groove below and closely adjacent the fuel port, and a piston slidably w ne mounted in said cylinder and provided with grooves for distributing oil in both directions from said oil inlet port.

6. A pump unit 'for fuel injectors comprising a cylinder provided with a fuel inlet port adjacent its upper end and a lubricating port between said fuel port and the lower end of said cylinder, the inner wall of said cylinder being provided with an annular groove "below and closely adjacent the fuel port, and a piston slidaloly mounted in said cylinder and provided with spaced annular V-shaped grooves, the lower sides of which are substantially horizontal While the upper sides are tapered outwardly for pro= gre ssively carrying oil upwardly over the inner wall of said cylinder to said annular cylinder groove for lubricating the tip of said piston.

7. A liquid fuel pump comprising a housing provided with a fuel distributing chamber closed to atmosphere and having an orifice in one of its walls, positive means for varying said orifice to meter fuel enteringsaid distributing chamber, a plurality ,0! pump units associated with said housing for the discharge of solid liquid fuel, and ducts closed to atmosphere forming communications between said distributing cliber and said pump units.

C F. HIGH.