US2881705A - Fuel injection pump - Google Patents

Description

April 14, 1959 w. STAEGE ETAL 2,881,705

FUEL INJECTION PUMP Filed July 18, 1955 INVENTORS Werner 6rae BY Rude F Schen mudkm'ssw-mjm United Statesv Pate t FUEL INJECTION PUMP Werner Staege, Freudeustadt, and Rudolf Schenk, Munich, Germany, assignors to Firma Kugelfischer Georg Schafer & Co., Schweinfurt, Germany Application July 18, 1955, SerialNo. 522,570

Claims priority, application Germany August 4, 1954 6 Claims. (Cl. 103-38) The present invention relates to fuel injection pumps, and more particularly to a control mechanism for regulating the amount of fuel supplied by such a pump by adjusting the extent of the piston stroke thereof. Although control devices of this kind permit a very accurate adjustment of the fuel supply, those known prior to this invention required rather complicated means for adjusting the piston stroke of the injection pump, which usually consisted of adjustable cams provided with inclined surfaces. Such devices had the further disadvantage that they were not suitable for any automatic adjustment, and were particularly not adapted for use with small engines due to the fact that they involved rather large forces for carrying out the respective adjustments.

It is therefore an important object of the present invention to provide a fuel injection pump which is especially adapted for use with small engines, and which includes a control mechanism for adjusting the extent of the stroke of the pump piston, the operation of which requires only minute forces.

Another object of the present invention is to provide a fuel injection pump which particularly lends itself to an automatic adjustment of the piston stroke in accordance with various conditions of operation of the engine.

A further object of the present invention is to provide a control mechanism for adjusting the piston stroke of a fuel injection pump which is of very simple design and construction and permits a highly ellicient pumping operation, as well as a very accurate adjustment of the pump either manually or automatically.

Still another object of the present invention is to provide a fuel injection pump whichis designed so that the control mechanism for adjusting the piston stroke and for thus regulating the amount of fuel supplied by the pump may be easily detached from the other part of the pump which may thus remain connected to the engine, thus rendering a readjustment of such part and of the engine unnecessary when the control mechanism should require any service which might involve its removal from the engine.

A feature of the invention for carrying out these objects resides in a piston pump, the piston plunger of which is divided into two separate coaxial parts, one of which is reciprocated by the engine and held in constant resilient engagement with a cam driven thereby. An adjustable control lever is further provided which engages with the main piston of the pump which is urged by a spring in a direction toward the first plunger so that it will carry out its return stroke automatically. Any pivotal movement of the control lever, either manually or automatically by a member of the engine in accordance with the operation thereof or by a separate control element which may be affected, for example, by a variation of the barometric pressure, will either raise or lower the main piston relative to the driving plunger and thus vary the distance between the two plungers. Thus,

2,881,705 Patented Apr. 14, 1959 the driving plunger may either be at all times in direct engagement with the main piston to pump the maximum amount of fuel, or the main piston may be raised by pivoting of the control lever so that the driving plunger in its upward stroke has to travel a certain distance before engaging the main piston. When so adjusted to various levels relative to the driving plunger, the main piston can only carry out a stroke smaller than the maximum stroke so that the amount of fuel pumped thereby will be reduced accordingly.

Although it may on first glance be assumed that the hammering action which is produced between the driving plunger andthe main piston might produce an undue acceleration of the main piston, as well as an undue pressure thereon and wear thereof, particularly if the pump is operated at a high speed, it has surprisingly been found that with a piston of a diameter as low as 1 inch and less such as is used in fuel injection pumps for small engines, a pump as designed according to the invention will operate safely, accurately, and efiiciently even at speeds as high as 6000 r.p.m. and more.

The use of a lever as a control member for varying the extent of the piston stroke of the pump has the advantage that the frictional forces involved in its operation are very small, and further that either or both ends of such lever may be acted upon independently of each other by manual control devices or automatically as a result of the functions and operation of the engine. For this purpose, the control lever may be pivotally mounted at one end on an eccentric which, in turn, may be adjusted by a suitable control device. Thus, the free end of the control lever may be pivoted by one control member about its pivotal axis, while when the other control member, for example, a bellows, acts upon the eccentric, the latter will pivot the control lever about its pivotal connection with the first control member.

According to a very simple embodiment of the invention, the control lever is interposed between the two coaxial plungers and has an aperture therein through which the driving plunger may pass so as to engage the main piston, at least during a part of its stroke. Since the surface of the control lever which engages the end of the main piston when the driving plunger is in its lower position would assume a slightly angular position relative to the lower end face of the main piston when the control lever is raised or pivoted from its neutral position to one where the two plungers are at any time spaced from each other, the adjustment would not be as accurate as desired, apart from the fact that the main piston would rest on the control lever only on a point of its edge which would thus easily become worn.

In order to assure a perfect surface contact between the main piston and the upper surface of the control arm, the present invention further provides a socket with cylindrical wall surfaces in the control arm which is disposed substantially coaxially with both plungers. This socket supports a partly cylindrical valvelike member which has a flat upper surface which is adapted to engage the end face of the main piston, and a central bore therein through which the pinshaped upper end of the driving plunger may pass so as to engage the central part of the end face of the main piston. The valvelike member is mounted in the side walls of the control lever adjacent the socket so as to be freely rotatable therein, so that at any angular adjustment of the control lever from its neutral position relative to the main piston, the valvelike member will turn at the slightest contact with the main piston and align itself automatically so that its annular upper surface will be exactly parallel to the end face of the main piston.

Further objects, features, and advantages of the present invention will appear from the following detailed deseription thereof, as well as from the accompanying drawing which illustrates diagrammatically and on anv therein partly in a cross section taken. through, the axis.

of the pump.

The pump. piston 1 which has a diameter of approximately 4 or less is slidably mounted in a pump housing 2, and the front end thereof extends into the cylinder chamber 3 provided within the housing 2. For properly guiding and sealing the piston 1, a packing 4 is provided which encloses piston 1 by means of a flange 5 which projects into the cylinder 3 and is securely mounted therein by means of a bushing 6 which is fitted into cylinder 3, a. packing ring 7 being interposed between the packing 4 and bushing 6' consisting of a material which is softer than that of which packing-4 is made.

Chamber 3 is connected by an intake suction valve 8 with an inlet 32 in which a coil spring 33 tends to main; tain valve 8 in a closed position. Inletchamber 32 in turn communicates with a fitting 34 through which the fuel may pass into the pump. Chamber 3 is further connected to a compression valve 9 which is mounted in a chamber 35 and acted upon by a compression spring 36. A suitable fitting 37 which is secured to housing 2 maintains spring 36 under pressure. An outlet pipe not shown in the drawing may be connected to fitting 37 to connect the pump to the engine. Rather than forming an integral part of housing 2, chamber 35 may also form a separate element fitted into housing 2 similar to chamber 32. Thus, all parts within housing 2 which are in contact with the fuel and have to sustain a high pressure and temperature are elements separate from housing 2 which can thus be made of a softer material, such as light metal.

The surface of the pump housing 2 where the piston 1 projects outwardly is removably secured to a second housing 10. In the particular embodiment of the invention as shown in the drawing, pump housing 2 is provided with a cylindrical sleeve 11 surrounding piston 1 which fits into a corresponding aperture 12 in housing and centers the two housings 2 and 10 accurately relative to each other. Mounted within sleeve 11 is a compression spring 16, the lower end of which acts upon a collar 17 on piston 1 to urge the piston downwardly along its path of movement. Under the action of spring 16 the lower flat end face 38 of piston or reciprocatable element 1 acts upon a control or abutment lever 15.

Housing 10 is provided with a larger chamber 13 into which the free end of piston 1 projects. A control lever is mounted within chamber 13 so as to be pivotable in the longitudinal direction of piston 1 about a pivot pin 14 which is disposed laterally'of the axis of piston 1. The pivot pin 14 cooperates with the right mounting end portion of abutment lever 15, as viewed in the drawings, to form a mounting means which mounts the abutment lever 15 for turning movement about a pivot axis located on one side of the piston axis in a plane substantially normal to the path of movement of the piston and spaced frlom the point of intersection between this path and this p ane.

As illustrated in the drawing, control lever 15 is disposed within chamber 13 so that its longitudinal axis intersects with that of piston 1. Since, due to its pivoting movement, control lever 15 will assume difierent angular positions relative to piston 1, lever 15 is preferably provided with a self-aligning device, which assures that the surface of lever 15 which engages the end face 38 of piston 1 will automatically align itself thereto so that any variation in the vertical position of lever 15 will be accurately transmitted to piston 1. For this purpose, lever 15 may be provided with a substantially cylindrical seat '18wforming a socket in which a cylindrical valvelike member 19 is seated so as to be easily rotatable therein. The member 19 forms an engaging element located at a portion of abutment member 15 which is in alignment with the path of movement of the piston 1. This member 19 has a central flat upper engaging surface 19' which the end face 38 of piston 1 is adapted to engage under the action of spring 16. Member 19 preferably forms a cylindricalv pin, the central part of which is ground-off to form the surface 19' while the cylindrical ends 39 thereof are rotatably mounted in the side walls of lever 15 which are disposed forwardly and rearwardly of the plane of the drawing and parallel thereto, Thus, member 19 is easily rotatable about an axis extending vertically to the plane of the drawing.

The valve-like, angle-compensating member 19. has a central o e 1 t er in nd n entr l f urfac and at right angles thereto. This bore 20 has a diameter smaller than that of end face 38 of piston 1, while the outer diameter of the annular surface 19' is larger than that of end face 38 so that despite any slight movement oflever 15 in a longitudinal direction thereof, end face 38 will always be in full annular engagement with surface 19".

On the lower end of housing 10 and coaxially with the centering projection 11, housing 10 is provided with a tubular extension 40 which serves as a bushing for guiding a driving plunger 21 which extends at its upper end into a pin 41 of a diameter sufiiciently smaller than that of bore 20 so as to permit the pivotal movement of lever 15, as well as a slight longitudinal movement thereof without coming in contact with the walls of bore 20. A coil spring 22 mounted on the tubular extension 40 acts upon a collar 42 on the lower end of plunger 21 so as to maintain the same in constant engagement with a cam 23 which is rotated by the engine.

The free end of lever 15 is connected by a rod 24 with a device, the operation or position of which is dependent upon the speed of the engine, for example, a centrifugal governor or other suitable means. Pin 41 is preferably made of a length so as to be in engagement with the end face 38 of piston 1 when cam 23 is in its lowest position and the engine is stopped. When the engine is then started, cam 23 depresses plunger 21 into housing 10, whereby pin 41 pushes piston 1 upwardly to compressthe fuel in chamber 3 and against valve 9 to open the same and to pump the fuel to the engine. In its downward stroke, piston 1 produces a suction in chamber 3, allowing valve 8 to open and to draw fuel into chamber 3. If the speed of the engine increases beyond a certain limit, connecting rod 24 will be raised, thereby pivoting lever 15 about itsaxis 14. Since. lever 15 is in engagement with piston 1, itwill raise the same against the action of spring 16 and thereby withdraw the end face 38 of piston 1 from engagement with pin 41 when cam 23. is in its lowest position, as shown in the drawing. Thus, in its upward movement, pin 41 must then pass through a certain distance before engaging piston 1 which is thus raised and lowered to a smaller extent in chamber 3, thereby pumping a smaller quantity of fuel to the engine.

In addition to its right mounting end portion shown in the drawing cooperating with the pivot pin 14, the abutment lever 15 has an opposite left mounting portion with" which a pivot pin 24' cooperates to form a mounting means which mounts the lever 15 adjacent its leftend, as viewed in the drawings, for turning movement about a pivot axis parallel to the axis of the pivot pin 14, and the connecting rod 24 of the centrifugal governor or the like forms a regulating means which cooperates with the mounting means at the left end of lever 15 to shift the pivot. axis provided by the pivot pin 24 in a direction substantially parallel to the path of movement of the piston 1. Thus, during upward or downward movement of the regulating rod 24 the abut ment lever 15 will turn about the axis of the pin 14.

A second control or regulating means for the injection pump may be provided to operate independently of the first mechanism indicated by the connecting rod 24. This mechanism consists of an eccentric regulating lever 25 on which lever 15 is eccentrically mounted by the pivot pin 14, and which is rotatably mounted about a pivot 43. Eccentric 25 has an arm 26 extending laterally from housing through an opening 44. The free end of arm 26 is pivotally mounted at one end of a bellows 27 of suitable construction, the other end of which may be acted upon by a stop member 29, the position of which may be manually adjusted in the direction 30 by a suitable operating member not shown in the drawing. The lower end of bellows 27 is acted upon by a compression spring 28 so as to maintain the same in engagement with the stop 29. A variation in barometric pressure or temperature acting upon bellows 27 expands or contracts the same whereby arm 26 pivots eccentric 25 about its center 43 and turns pivot pin 14 either upwardly or downwardly, thereby pivoting lever about pivot pin 24' at the other end thereof. Thus, surface 19 of the self-adjusting member 19 will act upon the end face 38 of piston 1 in the same manner as previously described to adjust the distance thereof relative to pin 41 of plunger 40, thus controlling the length of the stroke of piston 1 and the amount of fuel pumped thereby through the rotation of cam 23. Especially for starting the engine, stop member 29 may be raised, whereby eccentric will be turned in a counterclockwise direction as shown by the arrow 31, and piston 1 will be lowered relative to plunger 40, 41 so as to increase the length of the stroke of piston 1, as well as the amount of fuel pumped thereby.

By mounting those elements of the pump which are primarily subject to wear within a housing 10 separate from those elements which are less affected and connected to the engine through the inlet and outlet 34 and 37, respectively, the advantage is also obtained that this part 10 of the pump may be easily exchanged or removed for repair without requiring the other part, i.e. housing 2 to be also removed. Such a removal of housing 10 also permits an easy withdrawal of pump piston 1 from housing 2 if this should require replacement. Thus, such exchange or repair of the pump may be carried out without requiring any readjustment of the engine or a removal of the fuel lines from the pump.

Although our invention has been illustrated and described with reference to the preferred embodiments iereof we wish to have it understood that it is in no way limited to the details of such embodiments or to the specific examples described, but is capable of numerous modifications within the scope of the appended claims. Having thus fully disclosed our invention, what we claim is:

1. A fuel injection pump comprising, in combination, pumping means including a pump housing, a piston slidably arranged within said pump housing, and biasing means continuously urging said piston in one direction along its axis; adjustable abutment means limiting the travel of said piston in said one direction and including an abutment lever extending across the path of travel of said piston so as to be engaged thereby, first mounting means mounting said abutment lever adjacent one end thereof for first pivotal movement about a pivot axis on one side of said piston axis lying in a plane substantially normal to said path and spaced from the point of intersection between said path and said plane, first regulating means engaging and cooperating with said first mounting means for moving said first pivot axis in a direction substantially parallel to said path, second mounting means mounting said abutment lever adjacent an opposite end thereof for pivotal movement about a second pivot axis on the opposite side of said piston axis and parallel to said first axis, and second regulating means engaging and cooperating with said second mounting means for moving said second pivot axis in a direction substantially parallel to said path, so that said first regulating means cooperates with said first mounting means to turn said abutment lever about said second pivot axis and said second regulating means cooperates with said second mounting means to turn said abutment lever about said first pivot axis, whereby said first and second regulating means operate entirely independently of each other on said abutment lever; and driving means reciprocatable in the direction of said path between two predetermined limits for engaging said piston while the same abuts against said abutment lever for moving said piston against the force of said biasing means.

2. A fuel injection pump comprising, in combination, pumping means including a pump housing, a piston slidably arranged within said pump housing, and biasing means continuously urging said piston in one direction along its axis; abutment means limiting the travel of said piston in said one direction and including an abutment lever extending across the path of travel of said piston and having an intermediate engaging portion lying in said path to be engaged by said piston and a pair of mounting portions respectively located on opposite sides of and spaced from said engaging portion, a regulating lever mounted for pivotal movement about a first pivot axis which lies in a plane substantially normal to said path and which is spaced from the point of intersection between said path and said plane, and being pivotally connected to one of said mounting portions of said abutment lever to support the latter for pivotal movement about a second pivot axis which is substantially parallel to said first pivot axis and which is spaced therefrom in a direction substantially normal to said path so that limited pivotal movement of said regulating lever about said first pivot axis will cause approximately linear displacement of said second pivot axis in a direction substantially parallel to said path, and regulating means pivotally connected with the other of said mounting portions of said abutment lever to support the latter for turning movement about a third pivot axis parallel to said second pivot axis and for moving said other mounting portion together with said third pivot axis in a direction substantially parallel to said path, so that said regulating means turns said abutment lever about said second axis while turning of said regulating lever results in turning of said abutment lever about said third axis; and driving means reciprocatable in the direction of said path between two predetermined limits and adapted to engage said piston while the same abuts against said abutment lever for moving said piston against the force of said biasing means.

3. The combination defined in claim 2, including adjusting means connected to said regulating lever for pivoting the same about said first pivot axis.

4. The combination defined in claim 2 wherein said second pivot axis is located between said path and said first pivot axis.

5. The combination defined in claim 2 wherein said piston is substantially cylindrical, wherein said engaging portion of said abutment lever is formed with a bore which is in alignment with said piston and has a diameter smaller than that of said piston so that engaging between said piston and said engaging portion occurs along an annular surface, and wherein said driving means include a plunger which is in alignment with said piston and said bore, has a diameter smaller than that of the latter and extends through the same with clearance so as to engage the end face of said piston, whereby slight displacement of said abutment lever in a direction normal to said path does not interfere with linear displacement of said engaging portion in the direction of said path.

6. In an adjustable abutment arrangement for locating one limit of travel of a reciprocatable element having a flat end face, in combination, an elongated abutment member extending across the path of travel of the reciprocatable element and having a pair of mounting portions located on opposite sides of and spaced from said Pa h; a pa QfimQumn meansmeum ng, said butment memh ffqr a P v al m m nt qu 5 pair Q p t axesh szh pa s' e p e ve y o gh said m t n port ens and ach 0i. hi h e n, a i ane that is substan: a y n ma to sa d. pa hati en gn f. said. abutm membe w ich s n, lignment i h: a d. p w du im ted, p o l m v me t Qf a d abu mentme rh about on Or he other o aid P v t ax s, mo s bs an ia y leng: id: p th; nd, an n a n em nt, arri d y said abu men m ber. at s id: P0115911 hereof. which is in alignment with, said path, said engaging e1e menthav ng a at engag g urface. and; be ng o l relat ve tQ sai abu mentmembel; asue a ma n r hat, rre pe e of he im ed piv almaveme t Q1: said. ab t; meat m mbe r a ive of s id. pa said. fl..t mem m fr m n, pe pendieu at to,s;ais ip.at. he e y r espe tive Q j he. acatl q of, a d. enga ihglem nt alang, sjaisi. path, he flat e d. ace. th reeigmeatahleelement may, e in aqe-tq-faee on act with. sa d. fl t; surface. f; sa d, n a ing elemen sa d. nga in elemen e ng. formed w h. a b e. pass g here h rquh. a m extend ng: along a Pa h. o ha par o a: p un e may: xtend, hrough said bore intq engagement with the reciproeatable e1e-.

8 merit to move said reeipro catabl e element. a ay from said engaging element, whereby said engaging element has at its; flat engaging surface an annular area of con.- tact with they fiatend face of said, reeiproeatable, e1e.-- ment.

Ref-entices Cit d: in the file. of. this: patent- UN'ITED STATES PATENTS 1,099,449 Kimball V...., v June 9, 1914 1,640,509 Lowe Aug. 30, 1927 1,718,586 Schmidt June 25, 1929 1,968,831 Hessehnan Aug 7, 1934 2,029,941 Pokorney Feb. 4, 19.36. 2,148,112. Dillstrom Feb 2 193.9 .2. 5562. ec er lane 17,, 194.1, 2 264,898 Boa an i, Den 2, 1. 1 ,4 0, 7 Ch ndle v 3..., N0):- 5, 194.6v

FOREIGN PATENTS 160,536 Switzerland M31j'. 15, 1933 911,452 Germany ,.May'13 1954 985,469 France Mar; 14, 1951

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