US3101057A

US3101057A - Injection pump

Info

Publication number: US3101057A
Application number: US157081A
Authority: US
Inventors: Heiser Joachim
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1960-12-10
Filing date: 1961-12-05
Publication date: 1963-08-20
Anticipated expiration: 1980-08-20
Also published as: GB1001977A; DE1129770B

Description

Aug. 20, 1963 J. HElsER 3,101,057

INJECTION PUMP Filed Deo. 5, 1961 United States Patent Oiiice` 3,101,057 Patented Aug. 20, 1963 arenas? LUECTIGN PUMP Joachim Heiser, Bernhausen, Kreis Esslingen, Wurttemberg, Germany, assigner to Robert Bosch @.mbl., Stuttgart, Germany Filed Dee. 5, 196i, Ser. No. 157,631 Claims priority, application Germany Dec. l0, 1%@

' v `7 Claims. (Cl. T33-37) The present invention relates to pumps.

M-ore particularly, the present invention relates to injection pumps adapted to be used with internal combustion engines for supplying fuel to the cylinders thereof.

Although injection pumps are at the present time highly developed, nevertheless it is still necessary to provide two basic types of injection pumps. One type is" designed for operation `at relatively low speeds and the other type is designed for operation at relatively high speeds. Injection pumps are required to operate at very high pressures in order -to be able to 4transmit the fuel to the cylinders of the engine. Because of these high pressures there is always the problem of preventing fuel from leaking back to the inlet of the pump during the pressure strokes thereof. In pumps which are designed for slow speed operation, this problem is taken care `of by providing in the pump a valve means which will reliab-ly -prevent yfuel from flowing back to the inlet of the pump during the pressure strokes thereof, but such pumps cannot be used `for high speed operation because the'inertia of the valve means prevents the valve means from main-taining the inlet of the pump elo-sed olf from its pumping chamber during the entire part `of each pressure stroke. lt is therefore necessary at the present time to provide -for high speed operation a pump which does not have such la valve means and which is capable during 4high speed operation of preventing ilow of fuel back to the inlet of the pump. However, these pumps which are designed yfor high speed operation cannot prevent iiow of fuel back to the inlet of the pump if these pumps operate at `a relatively low speed. The only wlay to prevent fuel from owing back tothe inlet of the pump with a pump which does not include a valve means and which is designed for high speed operation is Ito provide the pump with cylinders and pistons of extremely large diameters to greatly increase the length of the path along which the fuel would have to iiow back to the inlet of the pump, and since it is essential that modern injection pumps be quite small and compact, it is not feasible to provide pumps of relatively large diameters fat their cylinders and pistons. f

It is, therefore, a primlary object of thepresent inven-` tion to provide lan injection pump which is capable of operating both at Alow and at high speeds without any danger of leakage of fuel back to the inlet of Ithe pump during the pressure strokes thereof while at the same time maintaining the dimensions of the pump relatively small and compact so that the pump of the invention while having a perfectly satisfactory size enabling it to be used without diiliculty with modern engines at the `same time can be used either for operations at relatively low speeds or for operations at relatively high speedsso that it becomes unnecessary to provide -two basically different pump designs depending upon whether the pump is to operate -at low speeds or high speeds. l

Another object of the present invention is to provide an injection pump which includes all of the best features of both the slow speed and the high speed designs while at the same rtime eliminating all of the disadvantages thereof'.

Still another object of the present invention is to provide an injection pump which is of an extremely simple design and which includes no more parts than conventional pumps while at the `same tirne being capable of operation at -both low ,and high speeds without any danger of leakage of fuel back to the inlet of the pump.

It is furthermore an object of the present invention to provide an injection pump which is rugged and reliable in operation and which will be capable of operating perfectly not only at relatively low and high speeds but also with rall types of `fuels and under all operating conditions.

With these objects in view, the invention includes, in an injection pump which is adapted to operate at relatively low and at relatively lhigh speeds, a cylinder having in its interior a pumping chamber; an inlet passage means provides for flow of `fuel into the pumping chamber and a discharge passage means provides for flow of -fuel out of the pumping chamber, and a piston means is located in lthe cylinder for reciprocation therein along pressure and 4suction strokes. A control means cooperates with the cylinder for opening the inlet passage Vmeans during each suction stroke of the piston means and for closing the inlet passage means during each pressure stroke of the piston means, and this control means opens the discharge passage means during each pressure stroke of lthe piston means a-nd closes the discharge passage means during each suction stroke of the piston moans. Under certain operating conditions, as when thepump operates with a relatively light fuel or as when the parts become relatively worn, this control means is incapable of preventing leakage of fuel back to the inlet passage means when the pump operates at relatively low speeds. A valve means is located in the path of fuel ilow through the inlet pas- -sage means to the pumping chamber for closing olf the pumping chamber from the inlet passage means during the pressure strokes of the piston means when the pump opcrates at relatively low speeds, and thus, in accordance with the present invention, the control means and the valve means cooperate -to prevent leakage of fuel back to the in- `let passage means during the pressure `strokes of the piston means when the pump operates at relatively low speeds and when the pump operates` at relatively high speeds.

The novel features which are considered as characteristic for the invention yare set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will -be best understood from the following description of a specific embodiment when read in connection with the accompanying drawing, in which one possible injection pump according to the present invention is illustrated in an axial sectional elevation with the discharge passages of the pump shown in an axial sectional plane which is angularly displaced from the axial sectional plane in which the remainder of the structure of the drawing is illustrated.

In the particular example which is illustrated in the drawing,` the pump of the invention has one cylinder Land piston and it is designed to supply fuel rto an engine of four cylinders, but it is to be understood that the invention is `applicable to pumps of any desired-number of cylinders fand can supply fuel to engines having any desired number of cylinders.

The pump illustrated in the drawing includes'a housing having a lower part 1 and an upper part 2 iixed to v the lower part I1. This lower housing part 1 rotatably supports the `drive shaft 3 of the pump, this drive shaft 3 being connected in a known way to the crankshaft of the engine so as to operate the pump in proper synchronism' with the engine. The drive shaft 3 iixedly carries at its upper end, Ias viewed in the drawing, a cam 4 having rat its outer periphery four downwardly directed camming portions 5 which are uniformly :distributed about the Aaxis of the coaxial `elements 3 and `4. A spring 6, in a manner described below, urges the camming portions 5 against rollers 7 which tare supported for free rotation respectively about taxes which are perpendicular to and 1- d Y located in a plane normal to the axis of the shlalft 3,

'these rollers 7 being located at equal radial distances from the axis of the shatt 3 and being. displaced with respect to each other by' 90 about the axis of the shaft 3. Thu-s, during each revolution of the shaft 3 this Vshaft together with the 'cam 4wi1l be reciprocat'ed back 'and forth -along the axis of the shaft 3 fo-ur t-imes. The rollers 7 are supported for rotation by the shafts which are in turn carried by the lower housing part 1 in the manner shown in the drawing. v

.Within the upper housing part 2 is xedly located a cylinder 8 which forms "the icylinder of the pump, and the spring 6 bears at its upper end, as viewed in the drawing, against a downwardly directed should-'er adjacent the lower end I.of .the cylinder `8, as viewed in the drawing. The other end of the spring 6 bear-s against a washer 9 which is carried by an upwardly directed shoulder ot an elongated member 10 so that this member 10 is pressed Y which is convex and which is urged by the spring 22 by the spring 6 against the cam 4 and through the member 1'0 the spring 6 maintains the cam 4 yagainst the rollers 7. The cam 4 fixedly carries an axially extending pin 11 which extends in'to a radial notch formed in the lower end of the member 10, as viewed in lthe :drawing, this radial notch having a width corresponding to the diameter of 'the pin 11, so that as a result with this construction the member 10 is constrained to rotate and reciprocate with the cam 4. It be noted that the member 10 has at its lower-end, as viewed in the drawing,

Va convex end face extending into a recess formed in the upper face of the member 4 andengagingthis member 4 in its recess. As will be apparent from the description below, the lower solid portion of the member 10 shown in the drawing forms a piston means while the upper tubular portion of the member 10 forms a -control means, and of course the control means and the piston means formed by the tubular and solid portions of the member 10 `both reciprocate and rotate as la unit in response to the action of the drive means formed by the parts 3 7.

The part of the cylinder 8 in which the tubular portions or control means of the member 10 is located forms the pumping chamber of the cylinder 8, and during reciprocation of the member 10 the piston means formed bly-the solid portion thereof will reciprocate along pressure `and suction strokes,- asv will be apparent from the description which follows. A valve means l12 is located within the tubular portion of the member 10. This tubular portion has a stepped bore. These stepped por- `tions l13, 14, 15 of the tubular part of member 10 have progressively increasing diameters, as shown in the draw-v ing, and the shoulder formed between the portions 14 and 15`of the bore of the tubular portion :of member I10 forms -a Valve seat for the valve means. The valve member isnprovided beneath the portion thereof which engages the valve lseat with elongated :guide ns slidably engaging the inner surface of the tubular portion of member 10 in the hone portions 13 and 14 thereof, as shown in the drawing.

A spring 16 for-ms part of the valve means and coopenatesjwith the valve `12, to urge it towand its closed position.` The upper end portion of the spring l16, as viewed in the drawing, engages :ajtransverse wall -17 'of an elongated-sleeve' member axially slidable within the upper bore portion .15 Vof the member 10, and the sleeve which has the wall '17 has la very close sliding lit in the lbore portion 15 so as to be fluid-tight at its slidable engagement with the member 10. I he sleeve has rat its upper end, as viewed in the drawing, an outwardly directed annular flange 18V which, in the illustrated position of the parts shown in the drawing, engages an inwardly directed y.annular yflange 19 of a sleeve 20 which is I.axially slide-ble within the upper housing part 2. A spring 22 which bears at one end against a cover member 23 which closes the upper housing part 2 bears at its opposite end against the upper end `of acylind-rical cap member 24 having -a lower lend face,- as viewed in the drawing,

against the transverse wall portion 17, so that the spring 22 maintains the cap 2-4 inthe position shown where this cap acts on the wall I17 to maintain the ange 18 in engagement with the flange 19. Of course, the spring 22 is stronger than the sprin-g 16. Y

The sleeve 20 is formed with a cutout which receives a pin 27 which is eccentrically fixed to an adjusting `member 28. The turnable adjusting member 28 is supported for turning .movementin a sleeve 29 which -is threaded into a suitable bore of the upper housing par-t2, and this member 28 has an outwardly directed flange engaging a shoulder in the interior of the member 29, as shown in the drawing. To the left of this ange the member 28 has an elongated shaft portion adapted to be turned in any suitable way 4by ythe operator, zand the sleeve 30 is threaded into themember 29 and engages the member 28 so as to restrain the member 2S againstV axial movement while permitting angular movement thereof. Thus, the operator by adjusting the .angular position :of the member 28 will adjust the elevation of the sleeve 2) in the housing 2.

The housing 2 is tormed intermediate its ends with 'an opening 32 through which itu-e1 reaches the pump. This opening 32 may be suitably threaded lso as `to be connected to a suitable conduit leading from any gear pump or the like which pumps iiuel from the tank rto the opening 32 so that in this way the duel is delivered to the pump. The cylinder 8 is -formed with aninlet passage means through which iuel lowsto the pumping chamber in the interior orf the cylinder 8, and this inlet passage means includes the annular groove 33 `formed in the exterior of the cylinder y8 and the series of openings 34 providing communication between the annular groove 33 and the interior of the cylinder 8. In the illustrated example there are tour sets of openings 34 displaced by with respect to each other about fthe axis of the cylinder `8, and in each set of openings 3,4 there are three openings located one above the other as illustrated. The control means which is formedby the tubular por; tion of the member 10 is formed with one set of three openings 35 located one above the other, and' during reciprocation and rotation of the member Al() the openings 35 will successively come into communication with the successive sets of openings 34 which are 'distributed about the axis of fthe cylinder 8. The angular position of the set ott openings 35 of the control means lformed by the tubular portion of the member lwith respect to the 'four sets of openings 34 which form the inlet passage means is such that during each suction stroke of the piston means lformed by ythe lower part of the member 10, when this member 10 moves downwardly, as viewed in the drawing, the set :of openin-gs 35 communicates with one of the sets of openings 34 while during each pressure stroke, when the member 10 moves upwardly, as viewed in the drawing, the set of openings 35 is situated between a pair of sets of openings 34 out of communication therewith so thatV in this way the control means opens the inlet passage means during each suction stroke Vand closes the inlet passage means, during each pressure stroke of the piston means.

'IheY upper housing part 2 is termed with (four openings 38 which are intennally threaded so as to be connected with conduits Eleading to the several cylinders of the internal combustion engine, and the cylinder 8 is formedwith 'a discharge passage means in the form of tour openings 37 which respectively communicate with the openings 38 and which are respectively coaxial there-A with, as indicated in the drawing. |I'he four openings 37 are also displaced by 90 with respect to each other about Y by the tubular portion of the member is additionally formed with en opening 36 which during reciprocation and rotation of the member .10 successively comes into and out `of communication with the several idischange passages 37. The angular position of the opening 36 with respect to the openings 37 is'such that during each pressure stroke of the piston means formed by the lower part of the member 1G the opening 36 will communicate with one of the openings 37 while during each suction stroke the opening 36 will be situated between and spaced from a pair of the openings 37 so that in this way the control means provides communication between the pumping chamber of the cylinder 8 and the discharge passage means 37 during each pressure stroke and cuts on communication between the pumpingchamber of the cylinder 8 and the discharge passage means 37 during each suction stroke of the piston means lformed by the lower, solid part of the piston 10.

The parts are shown in the drawing in thev position they take at the end of one of the suction strokes at the point when a succeeding pressure stroke is about to begin. rfhus, at this time the valve means 12 is closed. During the continued tur-ning of the shaft 3 the member 10 will of course move upwardly so that [the piston means formed by the lower portion of the member 10 will move along a pressure stroke. As a result the valve 12 remains closed and the fuel in the space between the valve 12 and the wall 1'7 is compressed. The pressure required to force fuel through the injection nozzle of a cylinder :of the internal combustion engine is lgreater .than that required to compress the spring 22 so that during the initial part of the pressure stroke the wall 17 together with `a cap 24 rnove upwardly lalong the axis of the cylinder 8. The cap 24 is guided for movement by the pin 25 which is carried by the cover 23 and which extends through the spring 22, and the cap 24 is capable of easily :sliding yaxially along the pin 25. Thus, during the initial part orf the pressure stroke the spring 22 will be compressed, the cap 24 and the wall 17 will move upwardly, and the volume of the space between fthe wall 17 and the valve 12 will remain unchanged so that no fuel will be ydisplaced at this time through the discharge passage means. However, before the end of the pressure stroke the cap 24 will engage the bottom end of the pin 25, as viewed in the drawing, so that continued axial displacement of elements 17 and 24 will be prevented, and thus at this time during the continued movement of the piston means along its pressure stroke Kthe valve 12 will approach the wall 17, compressing the spring 16 and forcing fuel out through the discharge passage means.

During the next following suction stroke the opening 36 of the control means Idoes not communicate with any of the openings 37 which form the `discharge passage means, but at this time the set of openings 35 of the control means communicate with fone of the` sets of openings 34` so that fuel flows into the pumping chamber of the cylinder 8 through the openings 35 and of course at this time, the valve 12 automatically opens so that the fuel ows into the space between the valve `i2 and the wall 17. It will be noted that because :the flange 18 engages the liange 19 the wall 17 cannot follow the rnernber 10 during the entire suction stroke of the piston means formed by the lower portion of the member 10, `so that as a result a suction is created between the lwall 17 and the valve 12 automatically yopening the valve 12 to admit fuel into the space between the wall- 17 and the valve 12. At the beginning of the next following pressure stroke the valve 12 closes automatically, as indicatedjin the drawing. 4 i

It is possible to regulate the amount of fuel displaced -from the cylinder 8 during each pressure stroke by adjusting the angular position of the adjusting member 28. rfhe maximum amount of fuel will be delivered by the pump of the invention when the member 2S is turned to i raise the sleeve 20 in opposition to the spring 22 so as to locate the lower end portion of the cap 24 permanently in engagement with the bottom end of the pin 25. As a result duringeach pressure stroke the wall 17 remains stationary and during the entire pressure stroke fuel is disp-laced out of the injection pump, so that in this Way a maximum amount of fuel may ybe delivered. On the other hand, it is possible to adjust the sleeve 20 so that no fuel will be delivered during each pressure stroke, `and this can be brought about by displacing the sleeve 20 downwardly, as viewed in the drawing, to a position where during the entire pressure stroke the wall 17 will move with the member 1i? without remaining stationary while the member 10 continues to move, and thus there will heno delivery under these conditions.

In order to fully appreciate the invention, the operation of the structure described above and shown in the drawing without the valve means l2 should be considered. If the valve means 12 were omitted then there would be no difficulties Vduring operation of the pump at high speeds. Under these conditions, even if the parts are relatively worn and even ifthe pump operates with a relatively light fuel, the length of time` that the set of openings 35 remains out of communication with the openings 34- during each pressure stroke is so short that there is no danger of leakage of -fuel from the pumping chamber back to the inlet passage means 34. In other words', during high speed operation there simply is insuflicient'time for the fuel to have an opportunity to leak back to the inlet passage means 34 during each pressure stroke, even if the valve means 12 were not present. However, during operation of the pump at a relatively slow speed the fuel could leak back to the inlet passage means 34 during each pressure stroke. The distance between the set of openings 35 and any one of the sets of inlet openings 34 at any given moment is at a maximum extremely small. Therefore, during relatively slow speed operation under certain conditions as when the pump operates with a relatively light fuel or when the parts become relatively worn, the fuel which is under relatively high -pressure in the pumping chamber could indeed leak back between the surfaces of the cylinder 8 and the member 1d to the inlet passage means 34. If the distance between the set of openings 35 and the sets of openings 34 were made great enough to prevent this result from happening, the `diameter of the cylinder 8 and the member 19 would be so large that the injection pump would have no practical utility. Therefore, under these conditions the valve means 12 functions to prevent leakage back to the inlet passagemeans 34. `Because ofthe presence of the valve means 12 it is not possible for fuel between the valve l2 and the wall 17 to leak back to the inlet passages 34 during each pressure stroke. On the other hand, during high speed operation the inertia of the valve 12 is such that it cannot become seated and unseated withthe precision and with the synchronism which is required. In other words, because of the inertia effects resulting from the high speed reciprocation and rotation of the member lil the member 12 during high speed operation cannot reliably remain on its seat in a closed position during the entire part of each pressure stroke. However, this is immaterial since the openings 35` at this time cooperatewith the discharge passages 34 to prevent the fuel from reaching the inlet passages 34. Therefore, while retaining all of the advantages of an injection pump designed for high speed operation, the addition of the valve 12 enables the structure also to operate in a perfectly satisfactory vmanner even under low speed operating conditions `and even with relatively light fuels and even after within the cylinder 8.

the parts have been relatively worn so that the seal between the exterior surface of the member 10 and the inner surface of the cylinder S is not absolutely fluid-tight at the high pressure prevailing during a pressure stroke lt will be noted also that with the structure of the invention the disadvantage of not being able to use a pump designed for low speed operation also at high speed operation is avoided, so that in this way with the structure of the invention the same pump can be used for operation both at low speeds and high speeds and with all type of fuel as Well'as under all operating conditions.

The injection pump of the invention is particularly suitable for use with light fuels and high speed Otto engines. Such fuels because of their low viscosity require an effective structure for preventing leakage back vto the inlet of the pump from the pumping chamber. However, the injection Vpump of the invention is also equally well vsuited for operation with other fuels.

It will be understood that each of the elements described above, or two or more together, may also find a useful applicationin other types of pumps differing from the types described above.

While the invention has been illustrated and described as embodied in injection pumps, it is not intended to be limited to the details shown, since various modiiications `and structural changes may be made' Without ydeparting in any way from the spirit of the present invention.

Without further analysis, the 'foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various Y applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics Vof 'the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In an injection pump, in combination, a cylinder having a pumping chamber therein; piston means in said cylinder Vadapted to reciprocate therein along pressure and suction strokes; inlet passage means Vleading to said pump- :ing chamber; discharge passage means leading from said vpumping chamber; control means connected to said piston means for movement therewith and cooperating with said inlet and discharge passage means for opening said inlet passage means during each suction stroke of said piston means and for closing said inlet passage means during each pressure stroke of said piston means, said control means opening said discharge passage means during each pressure stroke of said piston means and closing said discharge passage means 'during each suction stroke of said piston means, said control means .being capable of preventing leakage of fuel back to said inlet passage means duringth'e pressure strokes of said piston means when the pump operates at relatively high speeds but under certain operating conditions, as when the pump is used Awith a relatively light fuel or when the parts become Worn, being incapable of preventing leakage of fuel back to said inlet passage means during pressure strokes Vof said piston means when the pump `operates at relatively slow speeds; and valve means carried by said control means for movement therewith and located in the path of flow of fuel .from said inlet passage means to VVsaid pumping chamber for preventing fuel yfrom leaking bac-kto said inlet passage means during pressure strokes of 'said vpistorrmeans at relatively slow speeds of operation of the pump, said valve means, because of its inertia, being incapable of maintaining the pumping chamber closed off from said inlet passage means during the entire pressure strokes of said piston means when the pump operates at relatively high speeds, whereby said con- Y trol means and said 'valve means cooperate to prevent vleakage back to said inletpassage means yduring all speeds jof operation of the pump.

2. In an injection pump which is adapted to operate vat relatively Ilow as well as at relatively high speeds, in combination, acylinder having a pumping chamber; piston means located in sai-d cylinder and adapted to reciprocate therein along pressure and suction strokes; inlet passage means providing a path of fuel ilow into said 'F62 w pumping chamber; 4discharge passage means providing -a path of fuel flow out of said pumping chamber; control means connected to sai-d piston means for movement therewith and cooperating with said cylinder for opening said inlet passage means during each suction stroke of said piston means and -for closing said inlet passage means during each pressure stroke of said piston means, said control means opening said discharge passage means during each pressure stroke of said piston ymeans and closing said discharge passage means during each suction stroke of said piston means and said control means, under certain operating conditions as when the Ypump operates with -a relatively light fuel or when theparts become relatively worn, being incapable of preventing leakage of -fuel during pressure strokes of said piston means back to'said inlet passage means at relatively low speeds of operation of the pump; :and valve means carried 'by 4said control means for lmovement therewith and located between said inlet passage means and said pumping lchamber for preventing flow of fuel back to sai-d inlet passage means during pressure strokes of said piston means at relatively low speeds of operation of the pump, said valve means, because of its inertia, being incapable of maintaining said inlet passage means closed off from said pumping chamber during the entire pressure strokes of said piston means when said pump operates at relatively high speeds, whereby said control means land said valve means cooperate to prevent leakage of fuel back to said inlet ,passage means during pressure strokes of said piston `means at relatively low as well as at relatively high speeds of openation of the pump.

3. In an injection pump adapted to operate at relatively low as well as at relatively high speeds, in combination, a cylinder having a pumping chamber and formed with a pair of passages extending through the wall of said cylinder and axially displaced with respect to each other,one of said passages forming an inlet passage providing for a path of fuel `flow into the pumping chamber and the other of said passages forming a discharge passage providing for a path of fuel flow out .of said pumping chamber; an elongated member slidably located in said cylinder and having one portion which forms a piston means and another portion formed with a pair vof passages cooperating respectively with said pair of passages of said cylinder and forming a control means for controlling the opening and closing of said cylinder passages; means cooperating with said elongated member for axially reciprocating the same and for rotating the same in said cylinder so that the portion of said member which forms said piston means will reciprocate in said cylinder along pressure and suction strokes and the portion of said member which forms a control means will cooperate with said cylinder passages to close said inlet passage during each pressure stroke of said piston means and to open said inlet passage during each suction stroke of said piston means, said control means cooperating with said discharge passage for closing the'A latter during each suction stroke of said piston means and for opening said discharge passage during each pressure stroke of said piston means, and said member, under certain operating conditions as when the pump works with a relatively light fuel or when the parts become relatively worn, being incapable of preventing the leakage of fuel from said pumping chamber back to said inlet passage during each pressure stroke of said piston means of its inertia being incapable of reliably closing offV the pumping chamber from said inlet passage during the entire part of each pressure stroke of saidpiston means when Ithe pump operates at relatively high speeds, whereby the valve means and the control means cooperate to prevent the llow of fuel back to said inlet passage means during each pressure stroke of said piston means when the pump operates at relatively low -speeds as well as when fthe pump operates at relatively high speeds.

4. In an injection pump capable of operating at relatively -low as 'well las at relatively high speeds, in combination, a cylinder having a pumping chamber in its interior and formed in its wall with an inlet passage means providing for iuel flow into said pumping chamber and, axially spaced from said inlet passage means, with a discharge passage means providing for fuel ow out of said `pumping chamber; an elongated member slidable in said cylinder, having a tubular portion in said pumping chamber and overlapping both of said passage means and having a solid portion next to said tubular portion, lsaid solid portion yforming 'a piston means and said tubular por-tion of said elongated member being formed with passages cooperating with said inlet .and dischange passage means and forming a control means; drive means cooperating with said member -for reciprocating and rotating the same i in said cylinder, said piston means reciprocating along pressure and suction strokes when said member is reciprocated by said drive means and said control means cooperating during driving 4of said member with said inlet and discharge passage means for lclos-ing said inlet passage means duning each suction stroke of said piston means and for opening said inlet passage means during each suction stroke of said piston means, said control means cooperating with said discharge passage means kfor closing said discharge passage means during each suction stroke of said piston means and for opening said discharge passage means during each pressure stroke of said piston means, Yand said member, under ce1-tain operating conditions as when the pump 4operates with a relatively light fuel or when the parts become relatively worn, being incapable of preventing leakage of fuel back to said inlet passage mean-s during pressure strokes of said pistonV l means when the pump operates at a relatively low speed;

and valve means located in said tubular portion of said member between the passage thereof which cooperates with said ydischarge passage means and the passage there or" which cooeprates with said inlet passage means `for closing off the pumping chamber ,from said inlet passage means yduring pressure strokes of said piston means when the pump operates at relatively low speeds, said valve means, because of its inertia during reciprocation land rotation lof said member when the pump operates at relatively high speeds, being ineapable of maintaining said pumping chamber closed olf from said inlet passage means during the entire part of each pressure stroke of piston means when the pump operates at relatively high speeds, whereby said control means and valve means cooperate to prevent leakage of fuel back to inlet passage means during both relatively high and relatively low speeds of operation of the pump.

5. In an injection pump as recited in claim 4, said tubular portion of said member being formed in its interior with a shoulder providing a valve seat for the valve means.

5 inlet passage means, with a dischange passage means providing for tlow of fuel `out vof said pumping chamber; an elongated member slidably located in said cylinder and means cooperating with said member for reciprocating yand rotating the same in said cylinder, said elongated member having one portion which extends transversely across said cylinder 'and forms a piston means which reciprocates therein along pressure land suction strokes and having another portion which is tubular and which is formed Iwith passages which during rotation of said elongated member open said inlet passage means during each suction stroke :of said piston means and closes said inlet passage means during each pressure stroke of said piston means and which during each pressure stroke of said piston means opens said discharge passage means of said cylinder and closes said dischange passage means during each suction stroke of said piston means, said elongated member, under certain operating conditions as when the pump operates with a relatively light fuel or when the part-s become relatively worn, being incapable of preventing leakage of `fuel back to said inlet passage means dur-ing pressure strokes of said piston means when the pump operates at relatively low speeds, said ltubular portion of said member being formed in its interior with an axial, stepped bore having intermediate its ends a shoulder located between the part of said tubul-ar portion which cooperates with said discharge passage means and the part thereof which cooperates with said inlet passage means and said shoulder forming a valve seat; a valve member guided in said Itubular portion for axial movement between open and closed positions and engaging said valve seat in its closed position, said valve member engaging said valve seat during each pressure stroke of said piston means when the pump operates at relatively low speeds so as to cut olf the pumping chamber from said inlet passage means at low speeds of operation of the pump, and said valve member due to its inertia, when rotating and reciprocating with said elongated member during oper-ation of .the pump at relatively high speeds, being incapable of remaining on said valve seat during the entire part of each pressure stroke of said piston means when the pump operates at high speeds, whereby said tubular portion of said elongated member and said valve member cooperate to prevent flow of fuel ,back to said inlet passage means during both low and high speeds of operation of the pump.

7. In a pump as recited in claim 6, means cooperating with said cylinder for controlling the volume of said pumping chamber so as to regulate the `amount of fuel 5' discharged therefrom during each pressure stroke of said piston means.

References Cited in the iile of this patent UNITED STATES PATENTS Aldinger Mar. 15, 1960

Claims

1. IN AN INJECTION PUMP, IN COMBINATION, A CYLINDER HAVING A PUMPING CHAMBER THEREIN; PISTON MEANS IN SAID CYLINDER ADAPTED TO RECIPROCATE THEREIN ALONG PRESSURE AND SUCTION STROKES; INLET PASSAGE MEANS LEADING TO SAID PUMPING CHAMBER; DISCHARGE PASSAGE MEANS LEADING FROM SAID PUMPING CHAMBER; CONTROL MEANS CONNECTED TO SAID PISTON MEANS FOR MOVEMENT THEREWITH AND COOPERATING WITH SAID INLET AND DISCHARGE PASSAGE MEANS FOR OPENING SAID INLET PASSAGE MEANS DURING EACH SUCTION STROKE OF SAID PISTON MEANS AND FOR CLOSING SAID INLET PASSAGE MEANS DURING EACH PRESSURE STROKE OF SAID PISTON MEANS, SAID CONTROL MEANS OPENING SAID DISCHARGE PASSAGE MEANS DURING EACH PRESSURE STROKE OF SAID PISTON MEANS AND CLOSING SAID DISCHARGE PASSAGE MEANS DURING EACH SUCTION STROKE OF SAID PISTON MEANS, SAID CONTROL MEANS BEING CAPABLE OF PREVENTING LEAKAGE OF FUEL BACK TO SAID INLET PASSAGE MEANS DURING THE PRESSURE STROKES OF SAID PISTON MEANS WHEN THE PUMP OPERATES AT RELATIVELY HIGH SPEEDS BUT UNDER CERTAIN OPERATING CONDITIONS, AS WHEN THE PUMP IS USED WITH A RELATIVELY LIGHT FUEL OR WHEN THE PARTS BECOME WORN, BEING INCAPABLE OF PREVENTING LEAKAGE OF FUEL BACK TO SAID INLET PASSAGE MEANS DURING PRESSURE STROKES OF SAID PISTON MEANS WHEN THE PUMP OPERATES AT RELATIVELY SLOW SPEEDS; AND VALVE MEANS CARRIED BY SAID CONTROL MEANS FOR MOVEMENT THEREWITH AND LOCATED IN THE PATH OF FLOW OF FUEL FROM SAID INLET PASSAGE MEANS TO SAID PUMPING CHAMBER FOR PREVENTING FUEL FROM LEAKING BACK TO SAID INLET PASSAGE MEANS DURING PRESSURE STROKES