US2298936A

US2298936A - Fuel injection pump

Info

Publication number: US2298936A
Application number: US369101A
Authority: US
Inventors: Ernest C Gambrell
Original assignee: Individual
Current assignee: Individual
Priority date: 1940-12-07
Filing date: 1940-12-07
Publication date: 1942-10-13
Anticipated expiration: 1959-10-13

Description

06L 1942- E. c. GAMBR E L L 2,298,936

FUEL INJECTION PUMP Filed Dec. 7, 1940 4 Sheets-Sheet 1 INVENTOR.

Ernest C. Gambr'ell W EM ATTORNEY. v

E. C. GAMBRELL FUEL INJECTION PUMP Oct. 13, 1942.

' Filed Dec. 7-, 1940 4 Sheets-Sheet 2 INVENTOR. Ernest C. Gambrel] BY ATTORNEY.

E. C'. GAMBRELL FUEL INJECTION PUMP Filed Dec. 7, 1940 4 Sheets-Sheet 3 N VENTOR.

Ernest C. Gambrel] ATTORNEY.

Oct. 13, 1942.

Oct. 13, 1942. E. c. GAMBRELL FUEL INJECTION PUMP 4 Sheets-Sheet 4 Filed Dec. 7, 1940 IN VENTOR. wWJ W Ernest C. Gambrell HHHI HME ATTORNEY.

Patented Oct. 13, 1942 UNlTED STATES PATENT OFFICE FUEL INJECTION PUMP Ernest C. Gambrell, Wichita Falls, Tex. Application December 7, 1940, Serial No. 369,101

24 Claims.

This invention relates to an improvement in pumps for supplying periodic charges of liquid fuel to the combustion chamber of an internal combustion engine, such charge of liquid fuel being delivered to the combustion chamber of the engine near the end of the compression stroke of the engine piston.

More particularly, it relates to that type of fuel injection pump having a fuel intake port and fuel bypass or spill port or ports in a cylinder having a constant stroke piston therein, whereby the reciprocation of said piston in said cylinder covers and uncovers said port or ports in its working stroke.-

In pumps of this type now in use, the spill from the pump cylinder, either the pre-injection spill or the spill at the termination of injection, or both, is returned to the intake of the pump, with the result that the liquid fuel thus by-passed or spilled under high pressure and the rapid reversal of the course of the fuel through small ports tends to create a foaming condition of the fuel and small bubbles and eddies in the intake fuel which interfere with the accurate metering of the fuel, especially at high speed. Since the amount of fuel required to be injected by each stroke of the pump piston is necessarily very small, particularly in engines of the small highspeed type, it is evident that even the slightest bubbles in the intake fuel will tend to bring about a variance of the amounts of successive injections, with the result that a marked dissimilarity between successive injections is often exhibited under certain operating conditions.

It is the purpose of this invention to improve this general type of fuel injection pump in the following manner, to wit:

(1) By providing a fuel inlet or fuel intake port in the pump cylinder through which fuel enters the pump cylinder, and through which intake port the fuel cannot be reversed, and fuel once entering said pump cylinder through said port being prevented from being dispelled from the pump cylinder through the intake port;

(2) By providing a by-pass port in the pump cylinder spaced from the intake port, with which by-pass port a control edge on the pump piston (inclined with respect to the longitudinal axis of said pump piston) cooperates to open and close said by-pass port, said inclined control edge being provided at a side of an annular groove in the pump piston, and which annular groove is in communication at all times with the space in the pump cylinder ahead of the pump piston and through which communicating passage and bypass port the first portion of the fuel drawn into the pump cylinder is by-passed or diverted from the pump chamber before said edge covers said by-pass port to bring about the beginning of injection, the injection beginning when said inclined edge closes off said port, said inclined control edge being adjustable with respect to said by-pass port whereby different points of said edge may be made to close off said port to afford an adjustment of the beginning of the injection period; and

(3) By providing a second spill port in said pump cylinder spaced apart from the inlet port and the aforementioned spill port, through which the fuel that is spilled from the pump cylinder at the termination of the injection period is bypassed from a passage provided, to establish communication between said by-pass port and a point in the pump cylinder beyond the outward limit of the piston travel, preferably beyond the outlet valve of the pump. A second annular groove in said pump piston is formed with a second control edge inclined with respect to the longitudinal axis of said piston and which said control edge cooperates with said by-pass port to provide a slide valve to open and close said port, and which said control edge is adjustable to vary the point of such edge which uncovers such port to control the termination of the injection period.

By-passed fuel from each of the two by-pass ports is diverted to a space in the pump apart from the intake space thereof, and is returned to the fuel tank to be picked up again by the pickup pump and passed through the fuel filters before it can reach the intake space again, thus insuring a solid column of fuel at all times in the pump piston, free from all conditions which might interfere with the accurate metering of the fuel.

By the above arrangement, in cooperation with a check-valve in the intake fuel passage to the pump unit and a check-valve in the by-pass fuel passage from the pump unit, there can be no reversal of the course of the fuel, but rather its course becomes uni-flow, whereby the disturbing factors which tend to interfere with the accurate metering in other pumps of this type are eliminated and exact quantities of successive injections may be had under all operating conditions.

A further object of this invention is to improve pumps of this type whereby the control edge which determines the beginning of the injection and the control edge which determines the end of injection, may be adjusted simultaneously, a variation of the time of injection being had in proportion to the amount of injection, by the use of a one-piece piston having the two control edges thereon, or whereby the two control edges may be adjustable independently of each other for use if such independent adjustment is desirable, by substituting a sectional piston in which the control edges are incorporated in separate sections of the pump piston that are independently adjustable.

A still further improvement in this invention is the provision whereby such a pump when adapted for use on a multiple-cylinder engine, may be constructed so as to allow the various pump units to be simply and easily removed and replaced without the necessity for removing the pump from its engine mounting and without the necessity for dismantling the pump as a whole, thus saving time and money in making repairs in the event that certain pump unit or units might need to be replaced or repaired.

This pump may be designed and constructed insuch a manner as to have a pump housin which carries the actuating. means, the control means, the fuel intake manifold and the fuel by-pass manifold, and having the individual pump units inserted therein and secured thereto, said units being removable by simply removing the bolts which secure such units to the housing, for repair or replacement without disturbing the mechanism contained in said housing. This construction is further simplified by utilizing a passage in the bolts which secure the pump unit to the housing as a fuel passage to and from such pump unit, such arrangement providing for the insertion of check-valves in the fuel intake passage and in the fuel by-pass passage.

Further, this invention provides means for normalizing the pressure in the fuel injection line at the end of the injection period, to eliminate the possibility of fuel dribbling from the injection nozzle after the injection period has been terminated.

The accompanying drawings illustrate a preferred embodiment of my invention, together with a modification thereof, in which:

Fig. 1 is a partial side elevation of the improved pump with parts broken away and in section to show the construction;

Fig. 2 is a top plan view thereof;

Fig. 3 is an enlarged vertical cross section through a pump unit, taken on the line 33 of Fig. 1;

Fig. 4 is a horizontal section therethrough, taken on the line 4-4 of Fig. 3;

Fig. 5 is a side elevation of the piston thereof;

Fig. 6 is a disassembled side elevation of the parts of a unit removed from the pump housing;

Fig. '7 is a horizontal section therethrough, on the line 1-1 of Fig. 6;

Fig. 8 is an end elevation, partly in section, of a modified form of the invention;

Fig. 9 is a disassembled side elevation of the modified form of piston parts;

Fig. 10 is a diagrammatic sectional view of the pump, with'the piston on bottom dead center and with the intake port uncovered to admit fuel into the pump cylinder above the piston;

Fig. 11 is a similar View, showing the piston closing the intake passage;

Fig. 12 is a similar view, showing the discharge of the fuel into the engine cylinder;

Fig. 13 is a similar view at the end of the injection period and showing the lay-passing of fuel trapped in the injection line so as to normalize the pressure and to prevent injection nozzle dribbling;

Fig. 14 is a similar view, showing the suction stroke; and

Fig. 15 is a similar view, showing the piston uncovering the inlet port for admission of fuel into the fuel chamber.

The invention is shown as applied to a pump structure having four pump units adapted for supply of liquid fuel to a four-cylinder engine. In this construction, the body of the pump is designated generally by the numeral I, and is elongated to mount the pump units in spaced relation lengthwise thereof, all of which are adapted to be operated from a single cam shaft 2 operatively mounted in an opening 3 in the lower portion of the body, and having the opposite ends thereof closed by bearing plates 4 seowed to the body and journaling the cam shaft 2 therein.

The body I is provided also with

longitudinal passageways

5 and 6 therein for the intake of liquid fuel and for the exhaust of by-passed fuel, respectively, being connected with intake and exhaust pipes I and 8, respectively (Fig. 2). The

passageways

5 and 6 extend throughout the plurality of pump units and are provided for communication with the several units.

Each of the pump units is constructed, preferably, substantially as shown in Fig. 3, having a casing 9 which is seated upon the body I, with a depending flange I0 inserted into an upright bore II in the body I and sealed against leakage of fluid therebetween by a gasket I2. At opposite sides of the casing 9, transversely of the body I, are ears I3 seated upon the top of the body and longitudinally bored with bolts I4 and I5 inserted therethrough and having the lower ends of said bolts screw-threaded at I6 in the body I to secure the casing 9 rigidly in place on the body. A gasket I'I surrounds each bolt beneath the head thereof, while a gasket I8 surrounds the bolt between the adjacent ear I3 and the body I for preventing the leakage or escape of liquid fuel. These gaskets are made preferably of soft metal, such as copper or lead to facilitate the formation of elfective seals.

The bolt I4 is bored longitudinally at I9 and transversely at 20 adjacent one end of the bore I 9 in communication therewith which transverse bore 20 is in open communication with a surrounding groove 2I in position to communicate with a passage 22 in the casing 9, which passage 22 extends to an annular groove 23 within said casing 9.

The bore I9 is adapted to communicate at its lower end with an orifice 24 in a side of the intake passageway 5, under control of a check-valve 25 normally pressed to seated position in a cage 26 by a coiled spring 21. The cage 26 is screwthreaded on the reduced lower end of the bolt I4 to enclose and retain the spring-pressed checkvalve and to facilitate assembly thereof in the structure. This check-valve 25 permits fuel to flow from the intake passageway 5 to the bores I9 and 29, groove 2I, and passage 22, to the groove 23, under control of the pump piston for discharge from the pump.

The bolt I5 is bored longitudinally at 28 and transversely at 29 adjacent an end of the bore 28 in open communication therewith, which bore 29 is surrounded by a groove 30 in registry with a passage 3| extending to an internal grooved chamber 32 in the casing 9.

The longitudinal bore 28 is controlled by a check-valve 33 which seats against the end of the bolt in a cage 34 under the influence of a coiled spring 35 for controlling communication from said bore 28 to an orifice 36 in a side of the discharge passageway 6. This check-valve 33 permits the discharge of liquid fuel from the grooved chamber 32 through the passage 3|, groove 39 and

ports

29 and 28 to the orifice 36 for discharge through the passageway 6. The cage 34 is secured to the bolt by being screwthreaded on the end thereof to hold the checkvalve in proper position and to facilitate assembly of the structure.

Mounted in the casing 9, is a cylinder 31, having its lower end portion mounted on a seat 38 therein, with a depending flange 39 telescoped into the flange ll) of the casing for secure mounting of said cylinder 31 in the casing. The cylinder 31 has formed therein

lateral ports

46 and 4| in position to register respectively with the inner groove 23 and the grooved chamber 32 in the casing 9, the port 4| being arranged adjacent the upper edge of the chamber 32, while a port 42 is formed in the cylinder 31 adjacent the lower edge of the chamber 32, substantially in alignment with a part 42' at the lower end of a longitudinal passageway 43 formed in the cylinder 31.

The cylinder 31 has a central bore 44 therein, to which the inner ends of the ports 46-43 extend, and the upper end of the bore 44 forms a pump chamber 45. above a piston 46 mounted in the bore 44 for reciprocating movement therein; The piston 46 is formed with

annular grooves

41 and 48 therein spaced at different distances from the upper end thereof in position to register respectively with the ports 4| and 42-42 but adapted for alternate registry therewith. The lower edge of the groove 41 'and the upper edge of the groove 48 are formed in planes turned at acute angles to the axis of the piston 46, as shown at 49 and 5|], respectively, to Vary the timing of the closing and opening respectively of the ports 4| and 42' upon turning movement of the piston 46.

To provide for rotation of the piston 46, it is formed with a pair of lugs 5| on opposite sides thereof that are received in grooves 52 extending lengthwise in a sleeve 53. The sleeve 53 is provided with peripheral teeth 54 in position to mesh with a rack 55 extending lengthwise through the block for longitudinal movement therein.

The sleeve 53 is telescoped within a surrounding sleeve 56 fitted in the bore ll of the body I, which surrounding sleeve 56 receives in the upper end thereof the flange It) on the casing 9. The lower end portion of the surrounding sleeve 56 is cut away as shown in Fig. 6, to permit engagement of the teeth 54 by the rack 55, but said surrounding sleeve 56 is provided with a transverse shelf 51 therein upon which the gear sleeve 53 is seated and supported.

The lower end portion 46' of the piston is extended and passes through the gear sleeve 53 and shelf 51, being formed with a head 58 on the lower end thereof bearing against a follower 59 riding on the periphery of cam 59, formed on the cam shaft 2. The head 58 of the piston member is enclosed by a split ring 6|. This mounting of the piston member 46 on the conveyor 59 permits rotation thereof without undue friction. The piston member is held in bearing relation against the cam by a coiled spring 62 interposed between the shelf 51 and. the split ring 6|.

The "cylinder head 63 'is seated upon the upper end 'of the cylinder 31 and is held in place by a coupling member 64 screw-threaded into the upper end of the casing 9, a gasket 65 being interposed therebetwee'n to prevent the leakage of fluid. The coupling member 64 has a chamber 66 therein adapted for the discharge of fuel through a ."passage 61. The chamber 66 is in position to communicate with a passage 68 in the cylinder head 63, under the control of a check-valve 69 seating downward against the top of the cylinder head 63 under the pressure of a coiled spring 19 in the coupling member 64. The passage 68 is in axial alignment with the cylinder bore 44 and in position to communicate with the pump chamber 45 to receive fuel therefrom and to direct the same past the checkvalve 69 into the chamber 66. The cylinder head 63 has a plurality of passages 1| therein extending from the chamber 66 to an annular groove 12 in the lower side of the cylinder head in position to register with the passage 43 extending lengthwise of the cylinder 31.

Provision is made also for the discharge of the fluid from the pump chamber 45 through a passage 13 extending axially into the end of the piston 46 to the annular groove 41 therein for discharge of the fluid through the port 4| into the chamber 32.

In the operation of the pump, fuel is supplied at low pressure through the pipe 1 into the intake passageway 5, which said passageway 5 distributes the fuel along the entire length of the pump to the several pump units thereof. From the intake passageway 5, the fuel enters the orifice 24, flows past check-valve 25, thence through bores l9 and 26, groove 2|, passage 22, groove 23 and port 4U, into the pump chamber 45.

Asthe cam 66 is revolved by the cam shaft 2, as shown in Fig. 11, the piston is forced upward, first closing off the intake port 49-. The first portion of the fuel that is displaced from the pump chamber 45 by the upward inovement of the piston is by-passed through the axial passage 13 into the annular groove 41 then registering with the port 4|, as shown in Figs. 10 and 11, until the beveled or angular edge 49 reaches the upper edge of the port 4|, closing said port and preventing further by-passing of fuel therethrough.

When this occurs, as shown in Fig. 12, the fuel trapped in the pump chamber 45 is forced up-' ward through the passage 68 past the checkvalve 69 into chamber 66 and discharged through passage 61 connected with the fuel injection line leading to the injection noz'zle in the engine cylinder.

Fuel injection continues during the upward travel of the pump piston, until the beveled edge 56 uncovers the port 42' at the lower end of the passageway 43, as shown in Fig. 13, thus terminating the injection period. The uncovering of said port 42' and hence the registry of annular groove 48 with the ports 42' and 42, establishes communication between the injection passage (chamber 66) and the by-pass' chamber 32, so that the remainder of the fuel that is dispelled from the pump chamber 45 after the said port 42' has been opened. is icy-passed through passages 1|, annular groove 12, passageway 43, port 42, annular groove 48 of the piston, and through port '42 to the fuel by-pa'ss chamber 32.

All of the fuel that is diverted to the chamber 32, both the fuel that is by-passed from the pump chamber before the port 4| is closed to eiTect a beginning of the injection as well as the fuel that is by-passed after the port 42 is opened to terminate the injection, is delivered from said chamber 32 through passage 3|, groove 30,

passages

29 and 28, past check-valve 33 and through orifice 36 to the discharge passageway it is returned to the source of fuel supply through the line 8.

Since the port 42 is in open communication with the fuel injection passage at a point above the check-valve 69, it is evident that the uncovering of said port 42' for by-pass of fuel to the chamber 32 will relieve the pressure which would normally exist in the fuel injection line between the check-valve 69 of the pump and the injection nozzle, since communication is established between the pump chamber 66 and the by-pass chamber 32, as shown in Fig. 13. Thus, by normalizing the pressure in the injection passage after the check-valve 69 has been closed, the possibility of fuel dribbling from the injection nozzle after the injection period has been terminated is effectively eliminated.

The point in the upward travel of the pump piston at which the port 4| is closed and injection begins and the point in the upward travel of the pump piston at which the port 42 is opened to terminate the injection period, may be varied by longitudinal adjustment of the control rack 55 by which the piston is rotated, to cause different points of the inclined control edges 49 and 50 to cover and uncover the by-pass ports 4| and 42', respectively.

According to the axial position of the piston as shown in the drawings, the adjustment is set to deliver a maximum charge of fuel at the earliest timing in the stroke of the pump piston, while rotation of the piston will bring about later timing and a lesser amount of injection, and rotation of the piston through 180 from the position shown in the drawings will effect a complete cut-off of injection, since the port 42' will be uncovered by the edge 50 before the port 4| is closed by the edge 49.

When the cam 6!] passes over its peak, the piston 46 is withdrawn under the urge of spring 62, as shown in Fig. 14, until the upper edge of the piston uncovers the intake port 40 to admit a new charge of fuel to the pump chamber 45, as shown in Fig. 15, and continues downward to the position shown in Fig. 10, thus completing the cycle and being in position for repeating the operation, as described above.

Provision for relative adjustment of the control edges of the piston to afiord independent means for adjusting the beginning of injection and the termination of injection may be made, as shown in Figs. 8 and 9.

The construction of this modification differs from the structure hereinbefore described only in that a sectional piston is provided, having the two control edges formed in separate sections of the piston and having independent means of adjusting the various piston sections.

Disassembled as shown in Fig. 9, this piston is made up of

sections

46a, 46b and 15, section 46a having an annular groove with an inclined edge 49a and having a stem 14, connecting the same with section 15, section 46b having an annular groove with an inclined edge 50b.

Assembled as shown in Fig. 8, the section 46b is telescoped over stem 14 and said stem 74 is screw-threaded into section 15 and rigidly secured thereto by a lock-nut, as shown. Thus assembled, the various sections comprise a sectional piston having longitudinally aligned sections connected for unitary rectilinear movement while permitting independent rotary adjustment of the piston sections, the sections 46a and 46b being operatively mounted in the pump cylinder while the section 15 bears against the cam follower.

Lugs 5| aare formed on piston section 15 and are interfitted in longitudinal slots in gear sleeve 53a whereby rotary adjustment of the piston section 46a may be had through adjustment of toothed rack 55a meshing with the gear sleeve 53a. Lugs 5|b are formed on piston section 46b and are interfitted in longitudinal slots in gear sleeve =53b whereby rotary adjustment of the piston section 462) may be had through adjustment of toothed rack 55b meshing with gear sleeve 53b.

By relative rotation of the piston sections 46a and 46b the respective ports may be closed or opened in differently timed relation for accurately adjusting the beginning and the ending of the injection period.

It will be evident that the construction and operation of this pump provides for the passage of fuel therethrough in one direction only, thereby eliminating the disadvantages of using fuel which has been agitated under high pressure and which may have bubbles intermixed therewith or other characteristics which might interfere with accurate metering, regardless of speed or pressure. Once the fuel has passed into the pump, there can be no reversal of its course, the fuel which once enters the pump cylinder being either discharged to the engine cylinder or returned to the source of supply, such by-passed fuel to the fuel supply being directed to the pickup pump and passed thereby through the fuel filters before it can again reach the intake side of the pump.

Also, it will be evident that a construction is provided whereby simultaneous adjustment of the amount of injection and the timing of injection may be had, or whereby, by substituting a sectional piston, independent control of such amount and timing may be had.

Likewise, it will be evident that means have been provided in this construction for effectively eliminating the possibility of injection nozzle dribble after the injection period has been terminated.

Further, it will be evident that a construction has been provided wherein the pump unit or units may be simply and easily removed for repair or replacement without dismantling the pump or removing it from its engine mounting.

I claim:

1. In a fuel injection pump, the combination of a body having a cylinder, a piston therefor, a fuel intake passageway extending to the cylinder, a fuel injection passage connected with the cylinder, means connected with the piston for trapping a quantity of fuel in the cylinder in open communication with the injection passage, said piston being adapted to force the trapped fuel through the injection passage, a by-pass passageway separate from the intake passageway and having means connected therewith for directing fuel away from the pump body, and means for by-passing a portion of trapped fuel to said by-pass passageway.

2. In a fuel injection pump, the combination of a body having a cylinder with an intake passageway connected therewith and having an injection passage leading therefrom, a piston in the cylinder in position to trap a quantity of fuel therein from the intake passageway and to discharge the same through the injection passage, said injection passage being arranged in constant communication with the trapped quantity of fuel in the cylinder, a by-pass passageway having means connected therewith for directing fuel away from the pump body separate from the intake passageway, and means for by-passing trapped fuel to said by-pass passageway.

3. In a fuel injection pump, the combination of a body having a cylinder, a piston operatively mounted in the cylinder, said cylinder having a fuel intake passageway extending thereto for communication therewith, means for trapping a measured quantity of fuel in said cylinder, said cylinder having an injection passage leading therefrom at a point having constant open communication with the trapped quantity of fuel for discharge therethrough of the measured quantity of fuel, and means including a part connected with the piston for controlling the end of injection of said fuel and a by-pass con- I nected with the injection passage and extending to a point outside the pump body independently of the intake passageway.

4. In a fuel injection pump, the combination of a body having a cylinder, 2. piston operatively mounted in the cylinder, said cylinder having a fuel intake passageway extending thereto for communication therewith, means for trapping a measured quantity of fuel in said cylinder, said cylinder having an injection passage leading therefrom at a point having constant open communication with the trapped quantity of fuel for discharge therethrough of the measured quantity of fuel, and means including a part connected with the piston for controlling the end of injection of said fuel and a by-pass connected with the injection passage and extending to a point outside the pump body independently of the in-. take pasageway, and check-valves in said intake passageway and by-pass for controlling the flow of fuel therethrough.

5. In a fuel injection pump, the combination of a cylinder having a fuel intake port in a side thereof, said cylinder having a fuel injection passage leading therefrom and a separate fuel bypass passageway, a piston mounted in the cylinder having means for by-passing fuel from the cylinder to the by-pass passageway, and means forming a separate by-pass for fuel from a point between the piston and a portion of the injection passage and for directing said by-passed fuel to the by-pass passageway.

6. In a fuel injection pump, the combination of a cylinder having a pump chamber therein with an intake port in a side thereof and having an injection passage leading therefrom, a bypass pasageway separate from the intake port and adapted to direct fuel away from the cylinder, a piston mounted in the cylinder at one end of the pump chamber, means for by-passing fuel from the pump chamber to the by-pass passageway, and means forming a separate fuel by-pass extending from a point between the piston and a portion of the injection passage and leading to the by-pass passageway. Y

7. In a fuel injection pump, the combination of a cylinder having a pump chamber therein with a fuel inlet port in a side thereof and having a fuel injection passage in communication therewith, a fuel by-pass passage separate from the inlet port and adapted to direct fuel away from the cy inder. a b -pass chamber in communicati n with the bv-nass passage. a piston moun ed in the cvhnde nd having a by-pass therein in position for communication between the p mp c m d t e by-pass chamber, means connected with the piston for controlling said by-pass communication, and means forming a separate by-pass to Said by-pass chamber from a point between the piston and a portion of the injection passage.

v8. In .a fuel injection pump, the combination of a cylinder having a pump chamber therein with a fuel inlet port in a side thereof and 'having a fuel injection passage in communication therewith, a fuel by-pass passage separate from the inlet port and adapted to direct fuel away from the cylinder, a icy-pass chamber in c mmunication with the by-pass passage, said cylinder having separate ports therein to the by-pass chamber, a piston mounted in the cylinder and having an opening therein extending from the pump chamber to :a point in position for communication with one of said ports, and a separate bypass in position ,for communication with the other of ,said ports and extending from a point between the piston and a portion of the injection passage.

9. In a fuel injection pump, the combination of a cylinder having a pump chamber therein with an inlet port, and with an injection passage leading therefrom, said cylinder having separate byrpass ports in side portions thereof, ,a piston mounted in-the cylinder and having edge portions in position to control each of said ports, said piston having a by-pass extending therethrough from the pump chamber to a space adjacent the edge portion controlling one of the by-pass ports, and means forming a separate by-pass from a point in communication with the injection passage :to the other of said by-pass ports.

'10.. .In a fuel injection pump, the combination of a cylinder having a pump chamber therein with an inlet port in a side thereof, and with an injection'passage leading therefrom, said cylinder having separate by-pass ports in side portions thereof, a piston mounted in the cylinder and having edge portions in position to control each of said ports, said piston having a by-pass extending .therethrough from the pump chamber to a space adjacent the edge portion controlling one of the 'by-pass ports, and means forming a separate by-pass from a point in communication with the injection passage to the other of said by-pass ports, a discharge passageway having means of communication with the by-pass ports, and a by-pass passageway communicating with the cylinder and extending to a point in position for communication with the other by-pass port.

11. In a fuel injection pump, the combination of a cylinder having a pump chamber therein with an inlet port in a side thereof, and with an injection passage leading therefrom, said cylinder having separate by-pass ports in side portions thereof, ,a .piston mounted in the cylinder and having edge portions in position to control each of said ports, said piston having a by-pass extending therethrough from the pump chamber to a space adjacent the edge portion controlling one of the by-pass ports, and means forming a separate bypass from a point in communication with the injection passage to the other of said bypass ports, a discharge passageway having means of communication with the by-pass ports, and a -by-pass passageway communicating with the cylinder and extending to a point in position for communication with the other by-pass port, the piston edges for controlling the by-pass ports being arranged at acute angles to the axis of the piston, and means for rotating the piston relative to the cylinder to vary the position of the angular edges relative to the by-pass ports.

12. In a fuel injection pump, the combination of a casing having a by-pass chamber therein with a by-pass passage leading therefrom, said casing having an inlet passage, a cylinder mounted in the casing and having a pump chamber therein with an inlet port in a side thereof communicating with the inlet passage and having an injection passage leading therefrom, said cylinder having separate by-pass ports in a side thereof open to the by-pass chamber, a piston mounted in the cylinder and having an edge in position to control the inlet port, said piston having peripheral grooves therein in position for communication respectively with the by-pass ports, said piston having a bore extending from an end thereof in communication with the pump chamber to one of said grooves, said cylinder having a bypass passageway for communication from the cylinder through the other groove to th other by-pass port.

13. In a fuel injection pump, the combination of a casing having a bypass chamber therein with a by-pass passage leading therefrom, said casing having an inlet passage, a cylinder mount ed in the casing and having a pump chamber therein with an inlet port in a side thereof communicating with the inlet passage and having an injection passage leading therefrom, said cylinder having separate by-pass ports in a side thereof open to the by-pass chamber, a piston mounted in the cylinder and having an edge in position to control the inlet port, said piston having peripheral grooves therein in position for communication respectively with the by-pass ports, said piston having a bore extending from an end thereof in communication with the pump chamber to one of said grooves, said cylinder having a by-pass passageway for communication from the cylinder through the other groove to the other by-pass port, each of said grooves having control edges for the by-pass ports arranged at acute angles to the axis of the piston, and means for rotating said edges relative to the ports to present different peripheral portions thereof to the ports to control the time of by-pass therethrough.

14. In a fuel injection pump, the combination of a body having a bore therein, a casing mounted on the body over the bore and having laterally extending ears thereon, bolts extending through the ears into the body and securing the casing in place thereon, said casing having a pump chamber therein, a piston in said chamber, means in the body and extending through the bore for operating the piston, and intake and discharge passages extending through the bolts for communicating with the pump chamber.

15. In a fuel injection pump, the combination of a body having a bore therein, a casing mount- J ed on the body over the bore and having laterally extending ears thereon, bolts extending through the ears into the body and securing the casing in place thereon, said casing having a pump chamber therein, a piston in said chamber, means in the body and extending through the bore for operating the piston, each of said bolts having axial bores therein with means of communication between said axial bores and the pump chamber for intake and discharge of fuel relative thereto,

and check-valves mounted on the bolts for controlling the direction of flow through said bores.

16. In a fuel injection pump, the combination of a body, a casing mounted on the body, bolts extending through portions of the body and casing and securing the same together, a cylinder connected with the casing and having intake and discharge ports, and a piston in said cylinder, one of said bolts having a passageway therethrough connected with the intake port.

17. In a fuel injection pump, the combination of a body, a casing mounted on the body, bolts extending through portions of the body and casing and securing the same together, a cylinder connected with the casing and having intake and discharge ports, and a piston in said cylinder, one of said bolts having an axial bore therethrough forming a passageway and communicating with the intake port.

18. A pump comprising a cylinder having an injection passage leading therefrom for discharge of fluid from the cylinder therethrough, a cooperating piston in said cylinder, said cylinder having a plurality of overflow ports, piston-controlled means of communication from within the cylinder in advance of the piston to one of said ports, and separate piston-controlled means of communication between the injection passage and another of said ports.

19. A pump comprising a cylinder having an injection passage leading therefrom for discharge of fluid from the cylinder therethrough, a cooperating piston in said cylinder, said cylinder having a plurality of overflow ports, piston-controlled means of communication from within the cylinder in advance of the piston to one of said ports, and separate piston-controlled means of communication between the injection passage and another of said ports and wholly independent of the first-mentioned means of communication out of direct connection therewith.

20. A pump comprising a cylinder having a pump chamber therein with an injection passage leading therefrom for discharge of fluid from the pump chamber therethrough, a cooperating piston in the cylinder, said cylinder having a plurality of overflow ports, said piston having a plurality of overflow ports arranged to discharge respectively to the cylinder overflow ports, means of communication from the pump chamber to one of said piston overflow ports, and separate means of communication outside the cylinder from the injection passage to another of said piston overflow ports.

21. A pump comprising a cylinder having a pump chamber therein with an injection passage leading therefrom for discharge of fluid from the pump chamber therethrough, a cooperating piston in the cylinder, said cylinder having a pluraltiy of overflow ports, said piston having a plurality of overflow ports arranged to discharge respectively to the cylinder overflow ports, means of communication from the pump chamber extending through the piston to one of said piston overflow ports, and separate means of communication outside the cylinder in constant open communication with the injection passage and extending to a point of communication with another of said piston overflow ports.

22. A pump comprising a cylinder having a pump chamber therein with an injection passage leading therefrom for discharge of fluid from the pump chamber therethrough, a cooperating piston in the cylinder, said cylinder having a plurality of overflow ports, said piston having a plurality of overflow ports arranged to discharge respectively to the cylinder overflow ports, said cylinder and piston overflow ports being arranged for overflow therethrough alternately with delivery through the injection passage, and means for adjusting the time of communication between each of the respective piston overflow ports and the corresponding cylinder overflow ports.

23. A pump comprising a cylinder having a pump chamber therein with an injection passage leading therefrom for discharge of fluid from the pump chamber therethrough, a cooperating piston in the cylinder, said cylinder having a plurality of overflow ports, said piston having a plurality of overflow ports arranged to discharge respectively to the cylinder overflow ports, means of communication from the pump chamber to one of said piston overflow ports, and separate means of communication outside the cylinder from the injection passage to another of said piston overflow ports, said piston being constructed for adjustment of the overflow ports thereof relative to each other to vary the time of communication therethrough with the cylinder overflow ports.

24. A pump comprising a cylinder having a pump chamber therein with an injection passage leading therefrom for discharge of fluid from the pump chamber therethrough, a cooperating piston in the cylinder, said cylinder having a plurality of overflow ports, said piston having a plurality of overflow ports arranged to discharge respectively to the cylinder overflow ports, means of communication from the pump chamber to one of said piston overflow ports, separate means of communication outside the cylinder from the injection passage to another of said piston overflow ports, said piston being constructed in sections with the respective overflow ports thereof in different sections, and means mounting said sections for adjustment relative to each other to vary the time of communication through the ports thereof with the cylinder overflow ports.

ERNEST C. GAMBRELL.