US2166876A - Fuel injection pump - Google Patents

Description

July 18, 1939. E. M. PURDY FUEL INJECTION PUMP Filed Nov. 7, 1935 4 Sheets-Sheet 1 INVENTOR EVERETT M. PURDY 5 7.- 3 wwww m w T w. muunn m EX 5 4 z I W W.6

BY HIS ATTORNEYS July 18, 1939. E. M. PURDY FUEL niJEcnoN PUMP Filed Nov. 7, 1955 4 Sheets-Sheet 4 Patented July 18, 1939 ii "UNITED sr'rrras rum. mmcnon rm Everett M. Purdy, New Canaan, Coma,- assignor toEiaemann Magneto Corporation, New York, N. Y., a corporation of New York Application November '3, 1935, Serial No. 48,744

2 Claims. (Cl. 103-41) This invention relates to fuel injection pumps for internal combustion engines and more particularly internal combustion engines firing partially or wholly by the heat of compression and it is an object of this invention to provide an improved device of the type described of simple mechanical construction and small size which shall provide for the control of the fuel to all cylinders of the engine by a single adjustable '10 control valve equi-distant from all the pump cylinders of the device whereby improved metering and equal distribution of fuel to the various cylinders of the engine are obtained without the necessity for separate adjustments of fuel delivery to the individual engine cylinders. It is also an object of this invention to provide a fuel injection pump of such construction that the time of injection of the fuel inrelation to the position of the pistons of the respective cylinders may be advanced or retarded for all-cylinders simultaneously by rotating the pump casing on its mounting and in which the time at which the injection of fuel starts in each engine stroke is,

automatically advanced or retarded as the amount of fuel injected is increased or decreased respectively, and it is. also an object of this invention to provide a fuel injection pump which may be controlled by a governor of light and sensitive construction and which is flexible in its adapta- 39 tion to various conditions of installation.

In the drawings- Fig. 1 is a top plan view of a fuel injection pump constructed in accordance with this invention;

35, Fig. 2 is a view in side elevation of the fuel injection pump 'shown in Fig. 1, parts being broken away to show other parts more clearly;

Fig. 3 is a view in vertical section taken as on line 3-4 of Fig. 1;

Fig. 4 is a partial view in horizontal section taken as on line 4-4 of Fig. 3;

Fig. 5 is a fragmentary view in vertical section taken as on line 5-5 of Fig. 4 and showing one form of fuel control valve and its seat;

Fig. 6 is a fragmentary view in vertical section takenas on line 0-6 of Fig. 4 and showing a fuel injection plunger and the bushing or casing in which it operates: a

.Fig. 'i is a partial view in vertical section taken similarly to Fig. 3 of a fuel injection pump of modified construction;

Fig. 8 is a fragmentary view in horizontal section taken as on line H of Fig. '1; Fig.9isafragmentaryviewinvertical of the fuel control valve shown in. Fig. 7, the valve being raised from its position in Fig. I;

Fig. 10 is a fragmentary view in vertical section taken as on line lI-l0 of Fig. 11 and showing an injection plunger and. its casing of modi- 5 fled construction;

Fig. 11 is a fragmentary view in horizontal sectiontaken as on line ll-ll of Fig. 10;

.Fig. 12 is a fragmentary view in'vertical section of the structure shown in Fig. 10, taken as 10 on line I2-l2 of Fig. 13 so as to show other portions of the structure and with the injection plunger raised to its uppermost position;

Fig. 13 is a fragmentary view in horizontal section taken as on line l3-|3 of Fig. 12; 15

Figs. 14 and 15 are partial views in vertical sec tion of further modifications;

Fig. 16 is a fragmentary view in vertical section of the control valve shown in Fig. 5;

Fig. 17 is a fragmentary view in horizontal sec- 20 tion taken as on line l|-l'| of Fig. 16;

Fig. 18 is a fragmentary view in vertical section showing the upper portion of a fuel injection plunger of Fig. 15;

Fig. 19 is a partial view in vertical section of a a further modification;

Fig. 20 is a-fragmentary view in vertical section showing the fuel control valve of Fig. 19;

Fig. 21 is a fragmentary view in vertical section showing the upper portion of a fuel injection 30 plunger of Fig. 19;

Figs. 22 and 23 are'partial vertical sectional views showing further modifications; and

Fig. 24 is a fragmentary view, partly in vertical section showing, detached from the casing, an operating cam and cam follower for the fuel injection plunger of modified construction.

As shown in the drawings, referring particularly to Figures 1- to 6 inclusive, a fuel injection pump constructed in accordance with this inin vention comprises a casing consisting of a sub-' stantially cylindrical portion I having arectangular flange 2 at one end thereof by which it is secured to a correspondingly shaped flange 3 of a secondcasingportionl. The casingportion l is 6 also provided with an annular flange 5 which'flts within an opening i of the casing portion 4. Screws I threaded into openings in the flange 3 secure the casing sections together. The casing section I is provided with a plurality of bores or cylindrical chambers 8, one for each of the cylinders of the engine withwhichthepumpistobeused. Each of the constructions shown in the drawings are arrangedfor four of such chambers I placedwith their axes spaced uniformly in a circle about the central axis of the cylindrical portion I of the casing. The bores 8 vary in diameter at different portions of their length and in each bore 8 there is a tubular plunger follower I0 having one end thereof closed and which is slidably mounted in that portion of the bore 8 adjacent the casing portion 4 and held against turning by a. pin I2 which engages in a slot I4 formed in the side wall of the plunger follower. In each bore 8 there is also fitted a fuel plunger bushing or cylinder l6 which extends into the follower I8 and is of greater diameter at one end so as to engage with a shoulder I8 formed in the bore 8. The bushing I6 has a cylindrical opening or bore ofuniform diameter throughout its length in which is slidably mounted the fuel plunger or piston 28. The plunger 28 at one end extends beyond the bushing I6 to engage the closed end of the follower I8 and its projecting end is provided with a spring seat 22 held in position by a spring wire 24 which engages in a groove 26 in the plunger. The spring'seat 22 serves as a seat for a spring 28 which is confined between the spring seat and a shoulder formed in the bore 8 and which holds the end of the plunger 28 in engagement with the follower I8.

To operate the follower I8 and fuel plunger 28 the lower end of the follower I8 is recessed to receive a roller 38 mounted on a pin 32 which extends through a transverse opening in the follower I8 and is held in position by a spring wire 34 engaged in notches in the pin 32 and a groove in the follower I8. The roller 38 is positioned to be engaged by a cam 36 formed integral with a gear 38 on the end of a shaft 48 which is mounted in the casing portion 4 and arranged to be driven in suitable manner from the engine with which the pump is associated. The shaft 48 extends through a cylindrical boss 4 formed integral with the casing portion 4 and which is rotatably mounted in a bracket 4| suitably supported from the engine. A set screw 4|, threaded into the bracket 4! and engaging in a groove 4 formed in the boss 4 secures the pump casing to the bracket and permits of rotative adjustment of the casing with respect to the bracket. To provide for the free operation of the gear 38 and cam 36 the gear wheel is supported by a thrust bearing 42 and the shaft 48 is guided by a ball bearing 44, an oil seal 46 being provided between the bearings 44 and the face of the casing portion 4 in order to prevent leakage of the lubricant along the shaft 48.

Threaded into the bore 8 at the free end of the casing section I is a plug 48 which retains the plunger bushing IS in its position in the bore 8 and which is provided with a central opening having a portion thereof shaped to provide a seat for the check valve 58. The plug 48 above the valve 58 is bored to receive a coupling member 52 having a central opening which communicates with a chamber above the valve 58 and is enlarged immediately above the valve 58 to receive a spring 54 which returns the check valve 58 to its seat. A second coupling member 56 cooperates with the coupling member 52 in securing the end of a pipe 58 which connects the individual plunger bore to a cylinder of the motor with which the pump is associated.

At the axis of the casing portion I and equidistant from all of the plunger bores is a bore having an inner portion forming a chamber 68 which is'in communication through an opening 62 with a source of fuel supply. Above the chamber 68 the bore is of larger diameter and has seated therein a plug 64 which is held in position by a screw threaded plug 66. The plug 84 is provided with a plurality of passages 68 arranged on the circumference of a circle and communicating at one end with the chamber 68 and at the other end with a chamber I8 formed between the plug 64 and the plug 66. Centrally located in the plug 64 is a tapered bore which communicates at its upper end with the chamber I8 and at its lower end with the ports or passages I2 extending radially through the plug 64 and the body portion of the casing I to communicate with the bores of the plunger bushings I6 through grooves 14 formed in the bushing I6. In the tapered opening in the plug 64 is a tapered valve 15 having a cylindrical stem which is slidably mounted in an opening in the plug 66. The valve 15 is provided at its outer end with a head I6 which forms a seat for a spring I8 confined between the head I8 and a shoulder on the plug 66. The spring I8 tends to raise the valve 15 in the tapered opening in the plug 64. Ports or passages 88 extending radially from the chamber 68 communicate with grooves 82 in the bushings I6 and an axial port or passage 84 in each plunger 28 extends from the end of the plunger 28 to a transverse port or passage 86.

To control the fuel supplied to the engine cylinders by the pump the valve 15jis controlled by a governor 88 which may be of the usual ball type and which operates through lever 90 and links 92 to operate a lever 94 pivotally mounted as at 96 in a bracket 88 secured in the free end of the casing portion I. The'lever 94 has a bearing portion 99 which bears on the head I8 of the valve I5 so that operation of the governor will cause movement of the valve to restrict or enlarge the passage between the tapered valve I5 and the walI of the tapered port in which it is mounted so as to vary the supply of fuel therethrough. The governor 88 is arranged so that as the speed of the engine increases the lever 94 is operated to bear down upon the head I6 of the valve forcing the valve I5 closer to its seat against the action of spring I8 so as to restrict the flow of fuel to the bores in which the pump plungers 28 operate. The governor 88is driven through a shaft I88 on which is fixed a gear I82 which meshes with the gear 38, the shaft I88 and gear I82 being mounted in a casing I84 having a seat which fits one of a plurality of pads I86 formed on the casing portion 4, which pads surround openings through which the gear 38 is accessible. The pads I86 permit of the attachment to the casing portion 4 of various accessories used in connection with the injection pump such as the fuel transfer pump and the fuel filter.

In'the construction just described rotation of the cam 36 by the shaft 48 causes the cam 36 to engage the rollers 38 in succession and operate the followers I8and the plungers 28, shifting each follower I8 and plunger 28 between the position shown at the left-hand side of Figure 3 and the position shown at the right-hand side of Figure 3. The rate at which the plungers are operated and the time during which they remain in the different positions will be determined by the contour of the cam 36. As shown, the cam 86 retains each plunger 28 in position to maintain the ports I2 closed as shown at the right-hand side of Figure 3 throughout the time in which all the other plungers 28 arev bein p d. lowering each plunger to theposition shown at the left hand side of Figure 3 only when it is desired to flllthe chamber above the plunger 28 with fuel for the engine cylinder. With a plunger 26 raised, as shown at the right-hand side of Figure 3, movement of the cam 36 past its roller permits the plunger 28 to be moved to its lower or retracted position by the spring 28 and a partial vacuum to be established above the plunger 20 so that upon the opening of the port "I2 by movement of the plunger past the groove the plunger 28 causing the plunger 28 to seal the 14 fuel is drawn from the fuel chamber 60 through the. ports 68 in the plug 64, chamber I0, past valve I5 and through the passages 12 into the chamber formed by the bore in bushing I6 above the plunger 28. Further movement of the cam 86 causes the cam to raise the follower I and passage I2 and to place the fuel in the chamber above the plunger under pressure, forcing fuel past the check valve 50 and through the passage in the plug 52 and the pipe 58 to an engine cylinder.

In order that the fuel may be delivered to the engine cylinders in a finely atomized condition it is customary to place in the delivery nozzles spring-biased valves which open only at a high pressure so that as the plunger 20 forces the fuel f i with the groove 82 whereupon fuel under pressure from above the plunger 28 is vented through the passages 84 and 86, groove 62 and passage 80 to the fuel chamber 68 thus releasing suddenly the pressure above the plunger 20 and causing the valve in the delivery nozzle to cut off the supply to the engine cylinder sharply. Valve 58 seats immediately upon the fall of the pressure above the plunger 28 and prevents back flow of fuel from the pipe 58.

As the relative positions of the ports 86 and grooves 82 are determined and fixed the point at which the fuel injection to the cylinder is cut off remains fixed. The point at which the fuel injection starts will vary to some extent with the -amount of fuel supplied to the engine cylinders at each operation of the pump, thus, when the valve I is opened to a greater extent the chambers above the plungers 28 will receive larger quantities of fuel than when the valve I5 is more nearly closed and with larger quantities of fuel in the chambers above the plungers the pressure on the fuel is raised to the point at which discharge to the engine cylinder starts upon a shorter movement of the plunger, thus the dis charge starts earlier with a larger than with a smaller quantity of fuel. Both the time of beginning and the time of ending the injection of the fuel may be advanced or retarded simultaneously by rotating the casing with respect to a the bracket 4I. As the casing is rotated the cam 86, because of the connection by which it is driven from the engine, remains relatively fixed so that rotation of the casing varies the time relation of the operation of the pump plungers with respect to the operationof the engine pistons and makes the same adjustment simultaneously with respect 'to the pump plungers for all the engine cylinders.

In the modification shown in Figures 7, 8 and 9 the fuel plungers 28 are mounted and operated in the same manner as the plungers 20 of the previous modification but the operating cam need not have the same contour as cam 36 of Fig. 3. Each plunger 20, however, is provided with a groove III] which communicates through radially extending ports or passages 86 with a longitudinally extending port '84. The casin portion I is provided-with an axially positioned bore having therein a plug formed of a lower or. inner portion H2 and a. separate upper or outer portion H2 both portions being held in position by a plug 66 The lower portion I I2 of theplug has a central bore I [4 which communicates with the chamber 68 formed by the lower portion of the bore of the casing I and with angularly shaped grooves I I6 formed in the upper face of the portion II2 of the plug, the upper portion II2 of the plug closing the upper edges of the grooves so as to make closed triangularlyshaped passages II6 which communicate with the ports or pasages 12 leading to the bores for the plungers 20 The plug portion II2 has a bore which forms acontinuation of the bore H4 and mounted therein is a cylindrical valve I5 which may be operated in the same manner as the valve I5 of the previous modification. The lower or inner end of the valve I5 is flat so as to form a sharp cut-oif for the triangular passages II6, It will be noted that thepassages II6 have the narrowest portion thereof at the bottom and that the operation of thevalve 15 is the same as the operation of the valve I5 of the previous modification, that is, movement of the valve I5 in a downward direction cuts off the. supply of fuel to the chambers above the pump plungers 20 the tapering of the passages II6 serving to give a very fine graduation as the valve Guts off but the valve I5 controls the ports H6 individually instead of controlling acommon port as does valve I5 of the previous modification. In this modification ports or passages 88? establish communication from ports in the plunger bushings I6 to a fuel chamber II8 which, "as shown, is in communication through a port I28 with the fuel supply, but the chamber II8 may, if desired, be extended downwardly so as to connect with the chamber 68 which is in communication through the port 62 with the fuel supply as in the previous modification. In this modification as a plunger 20! is forced downwardly,

by its spring 28 fuel isdrawn from the chamber 60 through the passage H4, past the valve 15 and through a port II6 to the chamber above the plunger 20 Movement of the plunger upwardly by the cam forces the fuel past the check valve to the engine cylinder, ports M and 86 being closed by the bushing wall, until the groove III] in the plunger 2Il is connected to the passage 80 whereupon pressure above the plunger 20 is vented through the ports 84, 86, groove IIII and passage 80 to the chamber II8 whence it will pass through the passage I20 to the fuel supply or, if the connection be so made, to the chamber 60.

In the modification shown in Figures 10, 11, 12 and'13, the supply of fuel to the chamber above a pump plunger may be controlled by a valve, such as either of the valves I5, 15, and the discharge from the chamber above that plunger may be either to a fuel supply chamber or to a fuel chamber II8 as shown in the respective modifications. In this modification the upper portion of the plunger bushing I6 is spaced from the plug 48 and a washer I22 is placed between the plug 48 and the bushing It closing the direct passage from the chamber above the pump plunger 28 to the check valve 50. The pump plunger 20 is grooved as at I23 and I24 and from the groove I24 there extends a transverse port I26 which establishes communication from the groove I24 to the axial port or passage 84*. The bushing I6 is provided with a port or passage I28 which connects a chamber I30 below the valve 50 with the central bore of the bushing at a distance from the valve 50. The bushing I6 is also provided with a passage I32 which communicates with a port I34 formed in the washer I22 so as to establish communication from the chamber above the plunger 20 to the central bore of. the bushing I6 at a distance from the washer I22. The plunger 20 when released by the cam and forced down by its spring 28 creates a partial vacuum above the plunger 28? and upon the opening of the port 12 by the plunger fuel is supplied to the chamber above the plunger. Upon operation of the plunger by the cam to force the fuel to the engine cylinder movement of the plunger first closes the passage I2 and continued movement thereafter forces the fuel above the plunger 20 through the passage 84 to the port I26 and groove I24. Groove I24 establishes corrmiunication with the passage I28 as the passage 12 is closed so that the fuel is forced from the chamber above the plunger 20 through the ports 84', I26 and I28, chamber I30 and past check valve 50 to the engine cylinder. As the plunger 20 is raised the groove I23 of the plunger eventually establishes communication from the port I32 to the port 80 whereby fuel under pressure above the plunger 20 is vented through the ports I34 and I32 and the groove I23 of the plunger to port 80 and thence either to the supply chamber 60 or to the fuel chamber II8 according as port 80 is connected. In thismodification vapor which passes to the chamber above the plunger 20 will rise above the fuel causing fuel only to be forced through ports 84 and I 28 to the engine cylinder. The vapor is vented through ports I34 and I32 to the supply.

In the modification shown in Figure 14 the plungers 20 are formed as plain cylindrical plungers without ports or passages and the fuel control valve 15 is formed with an end of frustro-conical shape and controls a plurality of passages II6 leading to the bores of the pump plungers. The passages II6 are of triangular shape as in Figure 7 and the fuel is supplied thereto from the fuel supply chamber 60 through the passage H4 in the lower portion II2 of the plug. The operation of the control valve 15 is the same as that of valve 15 of Fig. 7, the ports H6 being fully closed when the portion of the valve of full diameter is placed in position over the ports. The tapered portion of the valve 15 provides a gradual closing of the valve. Retracting the plungers 20 causes fuel to be supplied from the fuel supply chamber 60 to the chambers above the plungers and operation of the plungers to force the fuel to the engine cylinders cuts off the passages H6 and forces the fuel past the check valves 50 to the engine cylinders iir the usual manner. In this construction it will be noted there are no ports provided for venting the pressure above the plungers 20 in order to give a sharp cut off of, the supply of fuel to the engine cylinders. The cam for operating the plungers 20 may have any suitable contour.

In the modification shown in Figures 15, 16, 17 and 18 the fuel supply valve li is shown Drovided with a threaded stem engaging the plug 66' for manual adjustment of the valve although, of course, this valve may be arranged for adjustment-by a governor as in Figure 2, if desired. The valve 15 is grooved as at I40 and its inner end portion I4I of, full diameter is shaped to provide a flat inclined surface I42 on one side of the valve which cooperates with a shoulder in the valve chamber in controlling the passage of fuel through the port H4 in the plug I43. Controlling a port common to all the pump sections of the device prevents slight irregularities in the port sizes from affecting the amount of fuel supplied to the 'engine cylinders. The pump plungers 20 of this modification are grooved as at I42, I44, and have an axial port 84' and transverse ports I46 and I48 communicating with the grooves I44 and I42, respectively. In this construction the chamber II8 surrounding the plug I43 may be connected to the source of fuel supply through the port I20 and through ports 80 to the bores for the pump plungers 20. The ports I I6 connect the bores for the pump plungers to the bore or chamber in which the valve 15* is mounted. In the operation of this device when a. plunger 20 is retracted fuel is supplied through port I20 chamber I I8 and port 80 to the pump plunger bore at the groove I44, thence through the transverse port I 46 and the axial port 84 to the chamber above the pump plunger. The port I48 and the groove I42 of the pump plunger are at this time closed by the bushing I6 and the upper end portion of the plunger, which is of full diameter, seals the port I I6. As the plunger is raised the port 80 is cut off and communication between the groove I 44 of the plunger and the bore for the valve 15 is established through the port II6 so that as fuel is forced from the chamber above the plunger 2|] past the check valve 50 to an engine cylinder, fuel is also permitted to pass through the port 84 and port I46 to the port IIS past the inclined surface I42 of the valve 'IS and through port II4 to the fuel chamber I50 which is'in communication through the port 62 with the fuel supply.

As a pump plunger is raised to its uppermost position communication is established between the groove I42 on the pump plunger and port 80 leading to the chamber H8 so that as the plunger attains its uppermost position the pressure above the plunger is vented through the port 84, port I48 and port 80 to chamber 8' releasing the pressure above the pump plunger and cutting off the supply of fuel to the engine cylinder.. During the first portion of the movement of the plunger from its uppermost position some fuel may be supplied to the chamber above the plunger from the fuel supply chamber II8 through the port 80 port I48 and port 84 and also from the fuel chamber 60 past the valve 15 and through ports IIG I46 and 84 Port 80*, however, is cut off very shortly after movement of the plunger 2i! starts and the port IIG is subsequently cut off and thereafter remains cut off, port 80 being reopened again upon movement of the plunger 28 to its lowermost position for the passage of fuel from the chamber 8 In this construction it will be noted that the fuel control valve 15 does not control the supply of fuel to the bore for the pump plunger but controls a by-pass or waste passage which vents aportion of the fuel from the bore for the pump plunger as the pump plunger is operated to force the fuel to the enginecylinder, the valve 16 supplied from the chamber 60 past and through the port 6 to the chamber above serving to control this discharge from the bore for each pump plunger. In this modification,

also, instead of having the pump plunger main-- tained' at its uppermost position while each of the other pump plungers is operated the operating cam is so shaped that the pump plunger is returned to its lowermost position after each operation and remains in the lowermost position while each of the other pump plungers is operated. Thus, as each plunger 20 is on its delivery or outward stroke, the remaining plungers arepositioned so that the ports II6 leading thereto are closed by the upper end portions of these plungers and the discharge of fuel except to the engine cylinder corresponding to the operating plunger or past valve 15 is prevented.

In the construction shown in Figures 19, 20 and 21 the fuel control valve 15 controls the passage of fuel through a waste passage from the bore of each of the pump plungers as in the modification shown in Fig. 15. The valve 15, however, differs from the valve 15 inhaving a groove, as at I40 which is in communication through transverse ports I50, an axial port I52 and bore I I4 of the plug I I2 with the chamber 60= so that the valve controls individual ports leading to the pump bores and not a port or passage common to all the pump sections as in the previous modification. In this modification, as in the previous modification, fuel is supplied through the port I20 to the chamber H8 and ports 80* to the bores above the pump plungers 20 and the waste from the pump plunger bores passes through passages II6 to the bore for the valve 15. The pump plungers 20 in this construction are each provided with a groove, as at I54 and an axial port I56 communicating through a transverse port I58 with the groove I54. The pump plunger 20 is made of such a length that at its uppermost position the upper end of the plunger does not cut oil communication between the chamber above the pump plunger and the port 6". In the operation of this device retracting a pump plunger 20 creates a partial vacuum above the pump plunger which may cause some fuel to be the valve 15 the pump plunger but when the pump plunger is returned to its lowermost or retracted position fuel is supplied from the chamber II 8 through the port 80 to the chamber above the pump plunger. As the pump plunger is moved upwardly the upper portion of the pump plunger cuts off communication through the port 80 and forces the fuel past the check valve 50 to the engine.

cylinder. The groove I54 of the pump plunger is sealed by the wall of the plunger bushing I6 until the plunger approaches its uppermost position when communication is established between the groove I54 andthe port 8Il thereby establishing communication from the chamber above the pump plunger through the ports I56, I56 and 60 to the chamber H8, venting the pressure above the pump plunger and cutting off the supply of fuel to the engine cylinder. As the pump plunger is moved upwardly, however, part of the fuel above the pump plunger passes through the port II6 to the groove I40of the valve 15 and through the ports I50 and 152, to the fuel chamber 60, the extent of this waste or bleed from the pump plunger bore being determined by the position of the valve 15'. The valve 15 may be adjusted either manually as in the modification shown in Figure 15 or by a suitable governor as shown in Figure 2 and the plunger 20 may be operated by a cam of any suitable contour.

In the modification shown in Fig. 22 a single port II6 connects the bore of the plunger bushing I6 with the fuel supply and a washer I22 having a port I60 is placed between the bushing I6 and the plug 48 which holds both washer and bushing in position. The plunger 20 is grooved as at I62 and a transverse port I64 establishes communication between the groove and an axial port I66 which extends to the upper face of the plunger 20. With the plunger 20 positioned as shown in Fig. 22 and fuel in the chamber above the plunger, operation of the plunger by the cam 36 raises the plunger to close the port H6 and force the fuel above'the plunger to the engine cylinder. The discharge of fuel continues until the plunger approaches its extreme outer position where communication is established from the chamber at the outer end of the plunger through ports I66 and I64, groove I62 and port IIIi whereby fuel under pressure is vented from the chamber to the fuel supply and the discharge to the engine cylinder is stopped. As the cam passes and the spring 28 returns the plunger to the position shown in Fig. 22, some fuel may pass from the fuel supply through port II6 groove I62 and ports I64 and I66 to the chamber above the plunger but the port I I6 is almost immediately closed by the plunger and a partial vacuum is formed in the chamber above the plunger until the port II6 is again opened by the plunger 20 whereupon fuel flows through the port I IIi from the fuel supply.

In the modification shown in Fig. 23, a port I I6 connects the fuel supply to the bore of the plunger bushing I6 while a port 80 establishes communication from a fuel chamber with a groove I10 in the outer face of the bushing I6 which is connected by a port I12 with the bore in which the plunger is reciprocated. A washer I22 placed between the bushing I6 and the plug 46 and held in position by the plug is provided with a tapered recess I14 which is open towards the bore of the bushing I6 and with a plurality of ports I16 arranged in a circle about the recess I14. The plunger 20 has its upper or outer end tapered to enter the tapered recess I14 and is grooved as at I18. A transverse port I80 connects the groove I18 with an axial port I82 which extends to the outer end of the plunger. With the plunger 20 in its retracted position as shown 'in Fig. 23 and fuel in the chamber above the plunger operation of the plunger by a cam 36 shifts the plunger to close the port 6 and to force the fuel through the ports I16 in the plug I22 and past the check valve 50 to the engine cylinder until the movement of the plunger causes the groove I16 to register with the port I12 and open a passage for venting fuel under pressure from the chamber above the plunger through ports I62 and. I60, groove I16, port I12, groove I10 and port 60' to the fuel chamber whereby the discharge of fuel is forced through the ports I16. When the groove I18 is connected to the port I12 the'gas held in the recess is thereupon vented to the fuel chamber so that little or no gas or vapor is su plied to the discharge nozzles by the plungers 20 As the operation of the cam permits the spring 28 to retract the cam some fuel may be supplied from the fuel chamber to the chamber above the plunger through ports 80 and I12 but the movement of the plunger soon closes the port I12 whereupon a partial vacuum is formed in the chamber above the plunger until the movement of the plunger uncovers the port lli and fuel is supplied through this port from the fuel supply.

In this modification the ports I l6 and 80 correspond to the ports H6 and 80, respectively, of

I the structure shown in Fig. 7. Port H6 may be controlled as is port 8 and port 80' may be connected to the fuel supply as is port 80. The cams 36 operating the plungers of Figs. 22 and 23 may be of any desired contour.

While in the construction shown in Figure 3 the cam 35 has been shown as formed integral with the gear wheel 38 it need not be so as the cam may be formed as a separate member, as the cam 36 of Figure 24, which is secured to the gear wheel 38 by a bolt I60, the cam being positioned with respect to the gear wheel by a dowel pin I62.

cal valve chamber disposed on said axis of said casing and triangular ports at the meeting surfaces of said bushing sections connecting said valve chamber to said bores, pump plungers in said bores for forcing fuel from said bores to the cylinders of an engine, means for operating said plungers, means for venting fuel from the plunger bores to said ports for cutting off the flow of fuel from said plunger bores to the engine cylinders at a fixed point in the movement of said plungers and a cylindrical control valve in said valve chamber having a fiat end controlling said ports to govern the amount of fuel supplied to the pump plunger bores.

2. In a fuel injection pump for internal combustion engines, a casing having a plurality of plunger bores uniformly spaced in a circle about an axis of said casing, a sectional bushing in said casing forming a cylindrical valve chamber disposed on said axis of said casing and having triangularly-shaped connections individual to said bores at the meeting surfaces of the bushing sections, pump plungers in said bores for forcing fuel from said bores to the cylinders of an engine, means for operating said plungers, said plungers having ports for venting fuel from the plunger bores to said valve chamber connections at fixed points in the movement of said plungers and an adjustable cylindrical valve plunger in said valve chamber for controlling the supply of fuel to the plunger bores individually, said valve plunger having a flat end arranged to simultaneously control all fuel passages.

EVERETT M. PURDY.

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