US2519893A - Fuel injection pump - Google Patents

Description

Aug. 22, 1950 D. J. DESCHAMPS ET AL 2,519,893

FUEL INJECTION PUMP Filed Sept. 23, 1943 5 Sheets-Sheet 1 INVENTORS: DES/RE J flL-JCHAMRS and flOZ/GL/LS (ZAR/ff THEIR A TTORNE Y5 g- 1950 n. J. DESCHAMPS El AL 2,519,893

FUEL INJECTION PUMP Filed Sept. 23, 1943 5 Sheets-Sheet 2 I INVENTORfi: flEJl/PE fflarc/MMP; and 000 445 C CLARKE 3) 3w wow; fiat YHEJR ATTORNEYS g- 1950 I D. J. DESCHAMPS ETI'AL 2,519,893

FUEL INJECTION PUMP 5 Sheets-Sheet 3 Filed Sept. 25, 1943 L INVENTORj: flEJ/Af J DEJCHAMPS and fiouaz/zs (I CZAR/IE THEIR ATTORNEYS INVENTORS.

FUEL INJECTION PUMP D. J. DESCHAMPS ET AL Q Q Q Q Q Q Q lmm x Aug. 22, 1950 Filed Sept. 23, 1943 fiEJ/RE I 055 CH/IMPJ and OOUGLAJ C CLARKE THE/EATTORNEYS D. J. DESCHAMPS ET AL,

Aug. 22, 1950 FUEL INJECTION PUMP 5 Sheets-Sheet 5 Filed Sept. 23. 1943 INVENTORS. flfJ/REI dam/1M5 and 000 445 (624mm THEIR ATTORNEYS mama Aug. 22, 1950 FUEL INJECTION PUMP Desire J. Deschamps, Rutherford, and Douglas 0. chrkallountammltl assignorsto Corporation Dcschamps Fuel Injection York, N. Y., a corporation of New York Application September 23, 1943, Serial No. 503,470

' 16am. (or. 103-113) This invention relates to fuel injection pumps for internal combustion engines and has for its object the provision of an improved high pressure pump for injecting liquid fuel into the engine cylinders.

The operating speeds of such engines are con stantly being increased and the invention aims to provide a fuel injection pump which is capable of satisfactory operation at the highest engine operating speeds without lmdue wear, without mechanical failure and which requires a small amount of power for its operation.

The pump of the present invention can be applied to Diesel (compression ignition) engines, and to Otto-cycle (sparkignition) engines using volatile fuel such as gasoline. When used in connection with the latter, the attaining of the correct air-fuel ratio is of great importance and it is an object of the invention to provide a pump capable of adjusting th quantity of fuel injected with unusual accuracy.

In applications to Otto-cycle engines operating with a volatile fuel and having the fuel-air ratio adjusted by means of an automatic mixture control mechanism it is desirable for the fuel pump to have as nearly as possible a straight line delivery curve, and it is an object of the invention to provide an injection pump having this characteristic, that is to say, wherein the output of the pump varies substantially directly with the engine speed for a given throttle setting.

With Diesel engines it is customary to employ a type of fuel injection pump which provides fixed timing of the beginning of the injection, the end of the injmtion period being varied in accordance with the power demands of the engine. Although this type of pump has many advantages when applied to aircraft Otto-cycle, engines using volatile fuel, the general practice in this country still is to employ in connection with such engines a type of fuel injection pump which I provides fixed timing of the ending of the intion which is of such a nature that pmnps can be readily changed over from one type to the other with the substitution of a minimum number of parts.

The invention will be understood from a consideration of the accompanying drawings which,

2 by way of example, illustrate one specific embodiment thereof together wi a modification of one of its parts. In these dra s:

Fig. 1 is a vertical longitudinal section taken on the planes indicated by the broken line 'l--l 01' Fig. 2;

Fig. 2 is a vertical transverse section taken on brokenline22 ofFig. 1;

. Fig. 3 is a vertical longitudinal sectional view 01' a single pumping unit drawn to an enlarged scale;

Fig. 4 is a fragmentary vertical section taken on the broken line H of Fig. 1 and drawn to the same scale as that figure;

Fig. 5 is-a detail top view of the tappet construction shown at the left of Fig. 3 for actuating one of the plump plungers Fig. 6 is a view looking at the right hand end of Fig. 5;

Fig. 7 is a detail vertical section taken on line of Fig. 3;

Fig. 8 is a detail vertical section taken on line 8-8 of Fig. 1;

Figs. 9-12 are vertical sectional views of the pump cylinder, plunger and output control sleeve illustrated at the right of Fig. 3 showing the plunger in various positions under the conditions of maximum pump output;

Figs. 13-16 are similar views under the condition of no pump output;

Fig. 17 is a diagram showing the movement of the plunger in relation to the angular movement of the pump shaft;

Fig. 18 is a. view similar to the right hand portion of Fig. 3 illustrating a modified form of pump cylinder and plunger;

Fig. 19 is a fragmentary vertical section of certain parts shown in Fig. 1 shifted in their position for operation with the modified plunger and cylinder of Fig. 18;

Figs. 20-23, inclusive, are vertical sectional views of the pump cylinder, plunger and output control sleeve illustrated in Fig. 18, showing the plunger in various positions under the condition of maximum pump output and Figs. 24-27, inclusive, are similar views showing various positions of the plunger for the condition of no pump output.

Referring now to these drawings. and discussing first the general arrangement of the pump, it comprises three principal parts, namely, a drive housing I, a central dividing wall or tappet housing 2, and a head 3 containing the pump cylinders, plungers, the control assembly and the outlet valves. The three sections are held together by means of a series of screws i. The tappet housing 2 divides the pump as a whole into two main compartments, a front compartment within the head I and a rear compartment within drive housing I.

Drive housing I is provided with a mounting flange I by means of which the pump is attached to the usual mounting pad on the engine by a series of bolts or screws passing through holes provided in fiange I. In the rear compartment within drive housing I is mounted the pump shaft I which is splined at I at its outer end to provide a driving connection with the engine. Shaft I is mounted for rotation in its ball bearings I and I, the former being mounted in the end wall of the driving housing I and the latter in a part fixed at the center of the tappet housing 2.

Within the pump there are provided a plurality of pumping units as illustrated in Fig. 3, each comprising a pump cylinder I I (sometimes referred to as the cylinder barrel or bushing), a pump plunger ii, an output control member II and a plunger driving mechanism including a tappet structure indicated generally by numeral II and a slipper it. These pumping units are aranged in a circular row at equal distances from the axis of pump shaft I. In the embodiment illustrated in the drawings, twelve of these pumping units are shown, although any suitable number may be employed. and if the pump has more than about twelve cylinders it is desirable to arrange them in two concentric rows.

The pumping units are driven by means of a wobble plate II, the operating face ofiwhlch ens lcs the slippers ll of the several plunger driving mechanisms. Wobble plate II is angularly fixed with respect to pump shaft I and imparts a harmonic reciprocating motion to the respective plungers, the len th of the plunger strokes being fixed or invariable. Wobble plate II is preferably arranged not to rotate with shaft I. but merely to have its characteristic wobble motion imparted to it by the rotation of shaft I through the instrumentality of a thrust type ball bearing II angularly mounted on shaft I. The wobble plate is restrained from rotation by its frictional engagement with slippers II and may consequently "creep" or rotate slowly.

The tappet structura II are slidably supported in tappet hous ng I in such a manner as substantially to prevent the passage of fiuid ineither direction through this housing or dividing wall I. The details of this construction will be referred to later on. This enables the front compartment within head I to be utilised as an inlet reservoir for the fuel to be pumped and the rear compartment within drive housing I to be utilized as a collecting chamber for the lubricant for the tappets iI which are supplied with pressure lubrica-' tion also to be described below.

The fuel is supplied to the interior of head I preferably by means of the usual transfer pump which delivers the fuel under a pressure usually of about pounds. The fuel is delivered through an inlet connection I! (Fig. 2), preferably through a filter element II, and thence upwardly through a passageway II cored in the lower part of head portion I to the interior of the compartment within this head. This compartment is therefore filled with fuel at all times.

At the top of the head I there is preferably arranged a housing It having a vapor eliminator connection 2|. Suitable es I2 and II convey the vapor from the interior of head I to the hand end of plunger il. Plunger II is provided with an axial passageway II leading from the face of the plunger, that is, from chamber II inwardly beyond the end of cylinder ll. Communicating with axial passage II are an inlet passage II and a pressure relief passage 21. Each of these two passages includes a circular groove II in the surface of the plunger and cross passages II communicating with axial passage II as shown in Fig. 3.

Cylinder II and plunger ll of Fig. 3 provide for fixed beginning of the iniection period, the ending of the injection period being variable to regulate the amount of fuel injected.

The ending of the injection is controlled by the position of control sleeve II, it being understood that this sleeve is shiftable along the surface of plun'rer ll. Inlet passage II coacts with the inner or left hand end of cylinder II to establish the beginning of the compression stroke or injection period and control member II is provided with a circular control edge at the right which cooperates with pressure relief passage I1 to terminate the compression or injection period as will be described in more detail presently.

The fuel in the compression chamber II is, during the compression stroke, forced out through the outlet valve Ill and flows through a longitudinal passage II to one of the outlet connections II. These outlet connections, one for each pumping mechanism, are arranged around the Periphery of tappet housing I as shown in Fig. I. It will be understood that suitable tubing leads from these connections II to the injection nozzles of he respective engine cylinders in proper sequence corresponding with the firing order of the engine.

Valve II is held against its seat at the center of valve seat member II by means of a helical spring It, the outer end of which engages a valve seat lock nut II which holds seat member II in position.

Pump cylinder II is made to have a close slip fit in its supporting aperture in the casting which forms the.pump head I. and is provided with a positioning flange II which engages a shoulder in head I. The cylinder is held in place by the engagement of valve seat member II which is forced against the end of the cylinder by the valve sea lock nut II.

This construction has the advantage that cylinders II can be readily removed and replaced with a modified form of cylinder such as shown in Fig. 18, should it be desired to convert or change over the pump to provide fixed timing of the ending of the injection period, with the output controlled by varying the beginning of the injection period. The construction also is advantageous from the standpoint of production in that the cylinder barrels or bushings II can be finish lapped before they are inserted in pump head I, thus avoiding any lapping or touching up after assembly.

In Figs. 9-12, inclusive, various positions of pump plunger ii in the cylinder II are shown with the control member I! moved from the no output position of Fig. 3 to the right nearer the end of cylinder II in the position of maximum output. In Fig. 9 it is assumed that plunger Ii is at the extreme left hand end of its movement and is commencing a forward stroke toward the right. Fuel has fiowcd into the compression or workin space 24 through inlet passage or port It and axial passageway II during the previous return stroke and will continue to do so as the plunger moves forward, until the left hand 8 edge of port 28 passes the left hand end of cylinder II as is shown in Fig. 10. This cuts oh the inlet of the fuel to compression space 24, inasmuch as pressure relief port 21 is covered by output control sleeve I2, and causes the beginning of the injection period, that is, the beginning of the delivery of fuel through outlet valve 3'.

The delivery of the compressed fuel continues until the right hand edge of pressure relief port 21 passes the right hand or control edge of output control member I2 as shown in Fig. 12. This compression space 24 in communication with the fuel inlet reservoir in pump head 3 relieving the pressure on the fuel in the compression space, terminating the effective or delivery stroke and permitting outlet valve 30 to reseat itself. As the pum plunger II continues to the end of its forward movement, as shown in Fig. 12, the fuel continues to be forced back into the fuel inlet reservoir through relief port 21, as shown in Fig. 12.

During the return stroke of the plunger, fuel flows into the compression space 24 through inlet and relief ports 26 and 21 and passageway 28 under the transfer pump pressure. This is assisted also by the partial vacuum which is formed in the compression space during the period of closure of both the inlet and relief ports 26 and 21 as the plunger moves between the positions of Figs. 11 and 10, such vacuum exerting its iniiuence after inlet port 26 opens and until it is reclosed on the next forward stroke of the plunger.

Referring now to Figs. 13-16, inclusive, output control member I2 has been assumed to be moved back to the no pump output position of Fig. 3. When the plunger has traveled forward or to the right and closed the inlet port 26, as shown in Fig. 14, pressure relief port 21 opens simultaneously, the right hand edge of this port passing the right hand edge of control member I2 at this instant. Consequently the pressure in compression space 24 is relieved at the same instant that the inlet port 25 is closed, and throughout the entire movement of plunger II, as shown in Figs. and 16, the fuel within compression space 24 continues to flow back through passage and relief port 21 into the fuel inlet reservoir. Hence no fuel is delivered through outlet valve 30.

In Fig. 17, the motion of the plunger during a forward stroke is shown diagrammatically in relation to the angular movement of the pump shaft 6. At the 0 position of the pump shaft the forward motion of the plunger is assumed to commence, and corresponds to Fig. 9. From this point to the point A the motion of the plunger closes the inlet port 25, at which instant the injection period begins. This corresponds to Fig. 10. The injection period continues as the plunger advances from the point A to the point B which corresponds with Fig. 11 where the injection period ends for the maximum pump output. From the point B to the'top of the diagram represents the period during which the relief port 21 is open. I I

It will be understood that as the output control sleeve I2 is shifted to the left from the position shown in Figs. 9-12, inclusive, the injection period will be correspondingly shortened, the point B on the diagram of Fig. 17 moving to the left approaching point A as the injection period becomes shorter and shorter.

In diagram l1 it will be seen that during the effective stroke of the pump, that is to say, during the time of injection, or, in other words, as the plunger is moving between the points A and 6 B, the motion of the plunger is near its maximum velocity and this velocity is also substantially constant since this portion of the sine curve, which represents the motion of the plunger under the action of the wobble plate, has a substantially constant slope.

Referring now to Figs. 1 and 2, the output control members I! are shifted simultaneously to control the outputs of all of the pumping elements. This is accomplished by means of a disk 31 which is provided around its periphery with semicircular notches 38, the edges of which engage circular grooves 39 in the outer surfaces of output control members I2. Disk 31 is mounted for movement in the direction of its own axis to bring about this simultaneous adjustment.

For this purpose. disk 31 is fixed to or made integral with a cylindrical slide or plunger member 40 which is supported for longitudinal sliding movement in a circular aperture supported by the central dividing wall 2 opposite the end of pump shaft I. Slide member 40 is biased to the right, as shown in Fig. 'l, by means of a helical spring 4| and is moved to the left by means of a cam member 42 pinned to a cross shaft 43 and engaging a button 44 attached to the outer center of disk 31. Slide member 40, if desired. may be positively operated in both directions, avoiding the use of return spring 4|.

In order to rigidly support shaft 43 in the interest of obtaining extreme accuracy of the movement of control disk 21, the shaft is provided with bearings 45 adiacent cam 42. Shaft 43 extends through the outside wall of the pump head I, and preferably through both walls so as to permit a choice in the location of the pump control actuating lever 48 which is fixed to one of the projecting ends of the shaft. Packing glands 41 are provided to prevent the escape of fuel.

It will be understood that the pump capacity control lever 46 is actuated by the engine governor, or in case the pump is used on anengine having a fuel mixture control apparatus, then lever 46 is actuated by such apparatus.

It is of importance to accomplish the longitudinal shifting of the individual pump control members I2 on their respective plungers with the least possible friction and without the possibility of imparting a side pressure to the pump pistons II forcing or biasing them against the side walls of their respective cylinders III. This is important not only in the interest of obtaining accurate output control but also in preventing wear of the plungers and pistons under the high speed at which the pump operates.

For this reason the notches 38 in the edge of the common control disk 31 are cut somewhat larger than the diameter of the bottoms of the grooves 39 in the control members I2 and the edges of these notches are maintained out of contact with the bottoms of these grooves, as shown in dotted lines in Fig. 2. This is done by means of a stationary pin 48 (Fig. 1) which is fixed in the central dividing wall 2 and extends parallel to the axis of disk 31. Pin 40 has a cylindrical portion which passes through an aperture in disk 31, with the walls of which it makes a close sliding fit. Furthermore at the periphery of disk 31 (Fig. 2) is provided a rim 31a raised above the surface of the web through which are cut the semicircular notches 3!. This raised rim provides two narrow central surfaces at opposite sides of sleeves I2, avoiding binding between disk 31 and grooves 39 as might be the 7 case if there were a complete bearing all around the semicircular notches.

Referring now to the modification illustrated in Figs. 18-27, inclusive, there is here shown a construction of plunger and cylinder and output control mechanism which provides fixed ending of the period of fuel injection, the quantity of fuel injected being regulated by varying the beginning of the injection period. In this modification all the parts of the pumping unit are identical with that shown in Fig. 3 except the cylinder barrel or bushing I la and the plunger Ila. That is to say, the tappet II and slipper Il operate plunger I I a in the same manner in which they operate plunger II; also the various members of the pump housing such as the drive hous ing I, the tappet housing or dividing wall I and the head casting 3 and other parts of the pump are identical with those shown in Figs. l-l'l, inclusive, although a change in the position of the control cam II is necessary as will be referred to below.

Referring particularly to Fig. 18, cylinder Ila is provided with a relief opening ll which is spaced from its inner end. Plunger Ila is similar to plunger II in that it has a central axial passageway 25a but this passageway extends to a somewhat greater distance. inwardly of the plunger than the passage I! of plunger I l. Plunger IIa is also provided with inlet and relief passages but these are reversed in position with respect to inlet passages I6 and I1 of plunger II and are spaced a greater distance apart.

The inlet passage for plunger IIa is indicated by numeral 50 and cooperates with the left hand control edge of output control member II, instead of the right hand control edge, and controls the beginning of the injection period instead of its ending. The relief passage of plunger Ila is indicated by numeral II and cooperates with relief outlet 49 in the walls of bushing Ila to fix the termination of the iniection period. It will be understood that as in the case of plunger I I, the inlet and relief passages ll and II are constructed to produce the quickest possible cut oil and opening and for this reason embody the sharp edged circular grooves into which the cross passages from central passage Ila open. as illustrated in Fig. 1a and as previously described in connection with Fig. 3. It will also be understood that, like the construction of Fig. 3, the passages 25 and the cross passages are of large cross sectional area in relation to the volume of the compression space Ila in order to insure that this space is completely filled with liquid for each operating stroke and to aid in the ejection of vapor from this space so that the compression space at each stroke will be filled with "solid liquid.

For similar reasons relief opening ll in cylinder Ila comprises a continuous circular groove II cut in the interior surface of cylinder Ila and from this groove one or more small holes "open into the fuel inlet reservoir space within pump head I and surrounding the inner portions of cylinders Ila and plungers Ila. The inner control edge of groove II is a sharp circular edge to coact with a similar edge of the relief opening II.

Referring now to Figs. 20-23, inclusive, the output control sleeve I I is here shown in the position for maximum pump output and in Fig. 20 plunger Ila is beginning a forward or working stroke. The compression space Ila is in communication with the fuel inlet reservoir (the interior of pump head I) through axial opening Ila and inlet passage II and relief port II. This communication continues until the left hand edge of passage ll passes the left hand control edge of output control sleeve II and during this time a portion of the liquid which has filled compression space Ila on the previous back, or return stroke of the Plunger IIa is forced out into the fuel reservoir together with any vapor bubbles which may be included with it. The liquid left in the compression space Ila is therefore solid" liquid.

In Fig. 21 the plunger has advanced to the position just described and inlet opening ll has been closed by control sleeve II, and relief opening II remains closed by the walls of cylinder Ila. The injection period therefore begins at this point, the compressed fuel being forced out through the pressure operated outlet valve ll.

The injection period continues until the plunger has reached the position shown in Fig. 22 where the right hand or control edge of relief outlet II is just passing the left hand or control edge of the groove BI of relief opening II which again p aces compre sion space 24a In communication with the inlet fuel reservoir, thereby relieving the pressure in the compression space .and ending the injection period. Liquid from the compression space continues to be forced out through passages II and ll until the plunger reaches the end of its movement which is shown in Fig. 23.

On the return or back stroke of the plunger this communication still persists until the right hand edge of relief opening II again reachu the position shown in Fig. 22 during which time fuel from the inlet supply reservoir again flows into the compression space Ila through the central passageway IIa. After the position of Fig. 22 is reached where this communication is cut oil, a partial vacuum is formed in the compression chamber Ila as the plunger continues its back stroke to the position of Fig. 21 where this vacuum is broken by the passing of the left hand edge of inlet passage ll beyond the left hand edge of control sleeve II. At this point, the partial vacuum within the compression space is added to the pressure of the fuel within the head I produced by the transfer pump to cause the fuel to flow into the compression space Ila completely filling it. Then the plunger moves back to the position shown in Fig. 20 ready for a successive working stroke.

Now referring to Figs. 24-27, inclusive, the output control sleeve II has been moved to the right its maximum distance to the position of no pump output. Hence as the plunger commences its working stroke at the position shown in Fig. 24, as in the case of Fig. 20, the compression space Ila is in communication with the inlet fuel reservoir through the passage Ila and both the inlet passage ll and the relief passage II. Fuel (together with vapor, if any) is thereby forced out of the compression space through both passages until relief passage II is closed, and thereafter continues to flow out through the inlet passage II, as shown in Fig. 25.

The plunger advances to the end of its working stroke without compressing the liquid in compression space Ila and hence without producing any outflow of fuel through the outlet valve II for the reason that, as shown in Fig. 26, control sleeve II is in such a position that the inlet opening II is maintained open right up to the instant where the relief passage II meets relief opening in the cylinder. Afterwards, as shown in Fig. 27, the inlet opening is closed, but

asmses in Fig. 24. This again fills the compression space a with liquid ready for another forward stroke of the plunger so that, should the sleeve I! be shifted to the left from the no output podtion, the pump would be ready to deliver the amount of fuel corresponding to the position of sleeve 12.

In the comparison of Figs. 3 and 18, it will be been that when the pump is arranged to provide fixed beginning and variable ending of the micetion period, the no output position of output control sleeve I2 is at the left, whereas when the pump is arranged to provide a fixed ending and variable beginning of the injection period, the no output position of control sleeve I! is at the right. Consequently in order that the rotation of output control shaft 43 may be in the same direction to produce the same efi'ect, for example, to increase the output of the pinup, it is necemary to change the angular position of cam 42 from the position shown in Fig. 1 to the position shown in Fig. 19, wherein the opposite operating edge or back of the cam eoacts with button 44 to actuate the common control disk 31. This permits spring It to move disk 31 to the right so as to move control sleeve i2, adjacent the ends of cylinders Ila. to the proper position 35 to produce zero output of the pump. Hence the rotation of the shaft 43 and cam 42 to increase the output of the pump is in the same direction asitisinFig.1,asshownbythearrowsinthese two figures.

In order to adjust the control edges of output control members I! with respect to one another so as to obtain uniform delivery of fuel from each of the twelve pumping units, the constructionshowninFigs.3and7isemploycd. Each 45 a of the output control members it comprises an inner member or sleeve proper 54 which is threaded into an outer or body member 55, in the surface of which groove 39 is cut for the engagement of the control disk 31. By turning sleeve 54 with respect to body member 55 the control edges of the sleeve are shifted lon itudinally with respect to the body member.

The two parts are locked in adjusted position by means of a snap ring 58 having an inwardly projecting to ue 51. The left hand end of sleeve member 54 has a head in which a series of longitudinal equally spaced slots 58, for example, six

in number, as shown in Fig. '7, are cut. The left 60 hand portion of body member 55 is recessed to receive the slotted head of sleeve 54 and in the overlying wall of body 55 is a series of small holes I to receive the tongue 51 of snap ring 56 and allow it to project into one of the slots 58, thereby 5 locking the two sleeve members against relative rotation. The number of holes is is preferably one more, or less, than the number of slots it in the embodiment illustrated, there being seven of these holes making it possible to adjust one 70 facilitate accurate metering of the pump output, an important consideration is the avoiding of side loads on the pump .plungers II. This is obtained in the present pump construction, first, by utilizing the arrangement of inlet and relief ports for the pump cylinders ll previously described which provides balanced hydraulic loads on the pump piungers, and, second, by removing mechanical side thrust from the individual pump plungers by providing an improved plunger driving mechanism. This mechanimn includes an improved tappet construction and an improved slipper construction.

The avoidance of side thrust on the plungers, particularly when the pump is ham'lling volatile fuel such as gasoline, is of particular importance inasmuch as the lubrication qualities of such liquidaresubstantiallynilanditisimpracticable to make provision for the supply of lubricant to the walls of the cylinder and plunger. Yet these surfaces must slide upon one another with an extremely close fit in order to prevent leakage at the high operating pressures of such pumps.

The tappet structure indicated generally by numeral l3 (Figs. 3, 5 and 6) comprises two telescoping members, a push rod which is preferably made hollow, to reduce inertia forces and also to facilitate lubrication, as will appear later, and a thimble member 6| which affords a support for push rod member I and assists in coupling the tappet structm'e to the rear end of plunger II. To prevent leakage of fuel to the left of division wall 2 or lubricant to the right,

a packing ring ila is provided near the end of push rod member il between its outer surface andtheinnersurfaceofthimbleil.

Thimble ii slidably supports the tappet structure in an elongated guide bushing 62 which is fixed in the tappet housing 2, the two telescoping members BI and 6| reciprocating together without relative movement under the action of wobble plate 15, which, as previously mentioned, engages slipper ll.

Slipper II is mounted on the left hand end of push rod member I which is provided with an enlarged head 83 in the outer surface of which is a socket il in which is seated the semispherical surface 65 of slipper ll. Slipper l4 comprises a segment of a sphere, that is to say, a section of a sphere whose height is less than the radius of the sphere. In other words, the distance from the center of socket $4 to the wobble plate is less than the radius of the sphere from which the interacting socket surfaces 65 and I are formed. 7

Hence the frictional contact of the face of slipper M with the face of wobble plate l5 which tends to prevent the wobble plate from turning, has a negligible tilting effect upon the slipper about its pivoting point with respect to tappet member 6!, this pivot point being the center of the spherejust referred to. Avoidance of such tilting effect insures that the face of the slipper throughout its periphery is at all times in contact with the wobble plate. This is important in preventing non-uniform wear on the slipper which would eventually effect the length of the plunger stroke and interfere with accurate meter- Slipper H is held on tappet member Si by -a retaining member 68 which is fitted into a bore in the left hand end of member ii and fixed there by a pin. As indicated 3, member i6 isv provided with a retaining head 61 connected therewith by a reduced neck portion 68, by means 11 of which the slipper is permitted freedom of oscillatory movement in its socket.

Guide bushing 62 is tightly fitted into its aperture in tappet housing 2 and the outer surface of tappet member ii is also closely fitted to the interior of guide bushing II, the clearance being only sufficient to permit lubrication and the reciprocating motion of the tappet in the guide and the fit being close enough to prevent leakage of fuel from the fuel reservoir within the pump head 3 past tappet housing 2 or the leaka e of lubricant from the lubricant collecting reservoir at the left of tappet housing 2 into the fuel reservoir. Not only the close sliding fit of the tappet in the guide bushing prevents leakage of fuel past the tappet, but also the fact that the lubrication is done by a high viscosity oil (the engine oil) and at a pressure superior to that of the fuel pressure in the inlet reservoir.

Although guide bushings I are mounted in substantial alinement with the centers of cylinders Ill, it is impracticable in production to obtain sufficient accuracy to eliminate the impartation of side thrust or binding action to the plungers I I if the plungers and tappets are constructed as a single rigid member. Consequently in the present invention a self-alining coupling between the tappet It and pl-ungers ID has been provided.

In order to provide such a coupling arrangement plunger III is provided at its inner end with a coupling knob 69 connected to the plungers by a neck portion ill considerably smaller in diameter than the plunger. The end of push rod member it bears against the head of knob is and thimble member 6| extends beyond the end of push rod member ill and is provided with a bayonet joint which engages the underside of knob is.

This bayonet Joint is formed by means of a T-shaped slot 1| (Fig. in the side of thimble II which is adapted to receive the knob 68 and neck Hi. The body portion I2 of this slot is slightly larger than neck 10 and the top part of the T-shaped slot II is slightly larger both in width and in height than the knob II. The underside of knob .89 seats on the inner surface II of the end of thimble 6| which is displaced from the edges of T-shaped slot H. ables the tappet and plunger to be locked together during assembly which facilitates this work.

A plunger return spring 14 engages at its right end a shoulder on tappet guide bushing 62 and at its left hand end a flange 15 formed on the left end of thimble Ii. Return spring 14, acting through thimble ii and the inner surface of knob 68, forces the outer end of knob is against the'end of push rod member on which in turn forces the socket surfaces SI and it against one another and the face of slipper I4 against the face of wobble plate ll. Hence all reciprocating parts of the pumping umt are maintained in contact with one another, avoiding lost motion at any point under all conditions of operation of the pump.

However, a particularly important advantage of this arrangement is that damage to the pump is prevented in the event of the sticking" of a plunger in its cylinder. In such an event due to the fact that push rod 80 and thimble II are in push-pull connection with the plunger. these two members and the slipper H are held out of the path of the wobble plate, thus preventing the ipp Push rod and thimble constituting the plunger driving mechanism, from being thrown 12 violently back and forth each time the wobble plate rotates. This could result in serious damage, rapidly putting the whole pump out of operation.

The tappet mechanisms and slippers II are provided with pressure lubrication, the oil being received from the lubrication system of the engine and entering the pump from the mounting pad through a drilled passage It '(Fig. l) in drive housing I. From the right hand end of this pas. sage the oil enters a groove ll (Figs. 4 and l) in the face of tappet housing or dividing wall 2. Thence a sloping inwardly directed passage ll communicates with a circumferential groove is in the outer surface of guide bushing 02 for one of the lowermost pumping units (Fig. 4).

This groove not only serves to lubricate this particular pumping unit (as will be presently unmen-- derstood) but also serves to conduct oil to supply lubrication t all of the remaining pumping units, the oil flowing from the inner side of groove ll through a drilled passage III to a central circular groove 8i. Circular groove II is formed in the surface of a central bore extending through dividing wall 2 in which the support 40 for output control disk 31 and for shaft ball bearing I is fixed. From this circular groove 8|, other passages 82 similar to passage Ill radiate and carry the lubricating oil to the remaining eleven pumping units, each of the guide bushings I! having a circular groove 19 to receive the oil.

Referring now to Fig. 3, the oil from groove II in bushing 82 flows through a slopin hole ll in bushing which communicates with a groove 84 on the inner surface of bushing 62. During the reciprocation of the tappet l3 and at the inner end of each stroke a hole 85 in thimble ll momentarily registers with groove 84 and permits a small amount of oil to be discharged through it into a groove and a hole I! through the wall of push rod 60. Groove 84 also serves to supply oil to lubricate the sliding of thimble CI in bushing 62.

Oil from the interior of push rod 80 passes through a small groove II in retaining member 68 to lubricate the socket surfaces N and II of the slipper l4 and also to lubricate the coacting surfaces of the slipper and wobble plate. Preferably one or more small passageways it are provided to allow the oil to escape from the interior ofthe slipper so as to prevent the building up of oil pressure within the slipper which would tend to separate the slipper from the surface of the wobble plate and interfere with accurate metering,

The pump is provided with a device for determining when some particular pumping unit (which may be designated as pumping unit No. 1) has its plunger il in position corresponding to the beginning or the ending of the injection period depending upon whether the pump is provided with the cylinders or plungers shown in Pig. 3 or those shown in Fig. 18. This device comprises a timing pin N which is arranged to slide in a vertical aperture at the top of drive housing I. The pin is normally held in withdrawn position by means of a helical spring II but may be pushed down with the finger to bring its inner end into engagement with a groove '2 (Fig. 8) formed in the peripheral surface of atimingdisklt whichisflxedtopumpshaftl Just inside of ball bearing 0. Both the end of pin II and the surface of groove I: are so formed that the rotation of the shaft will force the pin out of the groove if the spring should fail to retract it. It will be .understood that the position of groove 92 in timing disk 93 corresponds to the beginning (or the ending) of the injection period.

The foregoing is an exemplifying disclosure of the improved fuel injection pump of the present invention, it being understood that the invention, in either its spirit or scope, is not limited to the particular construction and arrangement of the various parts of the pump illustrated in this disclosure, but that various changes in the mechanical expression of the inventive ideas set forth in this disclosure can be made without departing from the spirit and scope of the invention, which are intended to be set forth in the appended claims.

We claim:

1. In a fuel injection pump, a cylinder, a plunger therein, rotary cam means to drive the plunger, and driving mechanism between the plunger and cam means including a tappet memher, a, guideway therefor substantially in axial alignment with said cylinder, said tappet member having a push-pull connection to the plunger, said tappet having a spring biasing it into engagement with the cam means, whereby, in the event of the sticking of the plunger in the cylinder said driving mechanism is held out of the 4 path of the cam means.

2. In a fuel injection pump, a cylinder, a plunger therein, a wobble plate to drive the plunger, a support disposed between the cylinder and the wobble plate having an opening therein substantially in alignment with said cylinder, and driving mechanism between the plunger and wobble plate including a, push rod coacting with the end of the plunger, 9. suporting member for the push rod slidable in said opening, said supporting member having a laterally yielding connection with said plunger, and a spring biasing said supporting member in a direction to maintain the end of the plunger in contact with the push rod and said driving mechanism in engagement with the wobble plate.

3. In a fuel injection pump, a cylinder, a plunger therein a wobble plate to drive the plunger, driving mechanism between the plunger and wobble plate including a, push rod coacting with the end of the plunger, a supporting member for the push-rod having a push-pull self aligning connection with said plunger, 8. guideway for said supporting member substantially in axial alignment with said cylinder, and a spring biasing said supporting member in a direction to maintain the end of the plunger in contact with the push rod and said driving mechanism in engagement with the wobble plate, whereby, in the event of the sticking of the plunger in the cylinder, said driving mechanism is held out of the path of the wobble plate.

4. In a fuel injection pump, a cylinder, a plunger therein, a wobble plate to drive the plunger, a support disposed between the cylinder and'the wobble plate having an opening therein substantially in alignment with the cylinder, and driving mechanism between the plunger and wobble plate including a push rod coacting with the end of the plunger, a supporting member for the push rod slidable in said opening, said supporting member having a, self aligning connection with said plunger, and a spring biasing said supporting member in a direction to maintain the end of the plunger in contact with the push rod and said driving mechanism in engagement with the wobble plate.

5. In a fuel injection pump, a. cylinder, a plunger therein having a knob at its driving end, a wobble plate to drive the plunger, and driving mechanism between the plunger and wobble plate including cooperating pushing and pulling members, said pushing member coacting with the outer surface of said knob and said pulling member with the inner surface thereof and a, spring to actuate the plunger on its return stroke, said spring being arranged to act upon said pulling member to maintain the end of the knob in engagement with said pushing member and said pushing member in engagement with the wobble plate, whereby, in the event of the sticking of the plunger in the cylinder, said driving mechanism is held out of the path of the wobble plate.

6. In a fuel injection pump, a cylinder, a plunger therein having a knob at its driving end, a wobble plate to drive the plunger, and driving mechanism between the plunger and wobble plate including pair of telescoping members, one engaging the outer surface and one engaging the inner surface of said knob and a spring to actuate the plunger on its return stroke, said spring being arranged to act upon the telescoping member which engages the inner surface of the knob, whereby, in the event of the sticking of the plunger in the cylinder, said driving mechanism is held out of the path of the wobble plate.

7. In a fuel injection pump, a cylinder, a plunger therein having a knob at its driving end, a wobble plate to drive the plunger, a support disposed between the cylinder and the wobble plate, said support having an opening therein substantially in alignment with said cylinder, and driving mechanism between the plunger and wobble plate including inner and outer telescoping members, said inner telescoping member serving as a push rod to engage the outer surface of said knob, said outer member sliding in said opening and making laterally movable engagement with the inner surface of said knob, and a spring to actuate the plunger on its return stroke, said spring being arranged to act upon the outer telescoping member.

DESIRE J. 'DESCHAIVEPS. DOUGLAS C. CLARKE.

REFERENCES CITED The following references are of record in the file of this patent: 1

UNITED STATES PATENTS Number Name Date 1,570,023 Wilcox Jan. 19, 1926 1,916,948 Hartog July 4, 1933 1,933,081 Stephan 'Oct. 31, 1933 2,010,377 Sassen Aug. 6, 1935 2,081,390 Trapp May 25, 1937 2,091,037 Goode et a1 Aug. 24, 1937 2,093,477 Parsons Sept. 21, 1937 2,142,086 Alden Jan. 3, 1939 2,160,735 Hotter May 30, 1939 2,251,783 Davis Aug. 5, 1941 2,293,731 Frederickson Aug. 25, 1942 2,299,235 Snader et a1 Oct. 20, 1942 2,337,821 Huber Dec. 28, 1943 2,370,506 Tabb Feb. 27, 1945 2,413,115 Sheehan Dec. 24, 1946 2,445,266 High- July 13, 1948 I FOREIGN PATENTS Number Country Date 720,591 France Dec. 4, 1931 844,436 France Apr. 24, 1939

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