US2484926A

US2484926A - Injector operating mechanism for internal-combustion engines

Info

Publication number: US2484926A
Application number: US783560A
Authority: US
Inventors: Donald R Bennett; Bennett Pat; Richard C Young
Original assignee: F A SHIMER
Current assignee: F A SHIMER
Priority date: 1947-11-01
Filing date: 1947-11-01
Publication date: 1949-10-18
Anticipated expiration: 1966-10-18

Description

YOU/VG IN VEN TORS @et is, 1949.

HT'ORNEV Patented Oct. 18, 1949 INJECTOR OPERATING MECHANISM FOR INTERNAL-COBIBUSTION ENGINES Donald R. Bennett and Pat Bennett, Monterey Park, and Richard C. Young, Downey, Calif., assignors of one-half to F. A. Shimer, Los Angeles, Calif.

Application November 1, 1947, Serial No. 783,560

4 Claims. (Cl. 123-90) The present invention relates generally to internal combustion engines, and more especially to improvements in the construction of fuel injector operating mechanisms such as are commonly found in Diesel engines.

In engines of this kind it is conventional construction to have a plurality of cam rocker levers which are oscillated by individua-l cams on a rotating cam shaft and which, by their oscillations, individually reciprocate push rods which are operatively connected to valves and fuel injectors. The lever and push rod assemblies nor mally occur in multiples of three since the intake and exhaust valves and fuel injector for each .cylinder are operated individually by a separate engine becomes impaired. It is common practice at this stage to recondition the cam shaft by regrinding badly worn cams to restore them to their original shape, but they are then somewhat smaller since a portion of the metal is ground or worn away. The wear on all cams is not equal, wear on the injector cam normally ibeing considerably greater than on the valve operating cams because of the much higher operating pressure involved. The valve cams may not require grinding at all, even though the injector cams are reshaped.

When the reconditioned cam shaft is placed inv the engine, difficulties are encountered in properly timing the engine. Although the cams are similar in outline to their original shape, they are ordinarily somewhat smaller and the change in size is not necessarily uniform between all of the cams on the shaft. As a result of this situation there has occurred a change in the time in which the cam shaft operates any given rocker lever with respect to the position of the crank shaft and to the time of operation of other rocker levers. Since reconditioning of this type Vhas not ordinarily been contemplated by the manufacturer, there is no provision built into the engine to compensate for or adjust the timing after the engine is reconditioned.

The usual method of improving the timing of a reconditioned cam shaft is by placing shims between the engine block or frame and the housing enclosing the stationary bearing for the rocker levers, thus causing the housing to be shifted bodily away from the block, taking with it the rocker levers mounted on a shaft Within the housing. This causes all of the rocker levers to be shifted longitudinally with respect to the cam shaft; and, by trial and error, it is possible to approximate the correct timing of at least one, and sometimes more, of the rocker levers. However, assuming that the proper timing of the valve injector rocker lever of a cylinder has been achieved, it usually occurs that the timing of the rocker levers for the intake and exhaust valves has been made incorrect. This occurs in any given cylinder because there is no provision for diiferential movement between the rocker levers for the injector and the levers for the valves. Likewise, since a shift in the housing moves all the rocker levers for two or more cylinders, inability to provide differential movement [between the group of rocker levers for each individual cylinder means that one cylinder may be properly timed but at the expense of the timing of an adjoining cylinder.

Timing an engine by this method of trial and error is very time-consuming because the results of adding or removing any given shim cannot be redicted accurately in advance and it is very laborious to change the shims since the iixed shaft housing must be removed each time a thicker or thinner shim is inserted. It will be seen that this method of timing can result only in an approximation to correct timing since a compromise must often be effected between the several cylinders of an engine, as well as between the elements of a single cylinder. The end result is that the engine cannot be timed correctly and in such a way as to produce maximum operating eiciency.

Thus it is a general object of our invention to provide a valve operating mechanism for an internal combustion engine which includes means permitting accurate timing of the valves and fuel injectors in order to obtain maximum eiciency and performance from the engine, especially after the cam shaft has been worn or reconditioned and no longer has exactly its original sizeand shape.

It is also a general object of our invention to provide means, in the valve operating mecha- It is a further object of our invention to provide means in the valve actuating mechanism of an engine which permits relative movement, of the rocker lever arm operating the fuel injector of a cylinder with respect to the lever arms operating the valves of that cylinder. y

These objects of our invention have been attained by providing in an engine having a plurality of rocker levers oscillated by a rotating cam shaft, one or more stationary shafts each of which is provided with three bearings upon which rocker levers are mounted to oscillate. The shaft is mounted on the engine frame by 'means which -permit the shaft to be turned to selected positions about its longitudinal axis. Two of the bearings on the shaft have their axes concentric with the main axis of the xed shaft, while one bearing axis is eccentric thereto. As a result of this construction, the shaft can be rotated about its axis to move the rocker lever mounted on the eccentric bearing with respect to the cam shaft.

The eccentric bearing is preferably the bearing upon which is mounted the rocker lever for the fuel injector. Since this bearing is eccentric with the shaft axis, the associated rocker lever shifts longitudinally as the shaft is rotated; but the levers on either side of it, which actuate the exhaust and intake valves of the cylinder, remain unchanged with respect to the cam shaft. When adjusted to the desired positions, the shaft is locked to hold it xed in position.

By providing separate fixed shafts mounted concentrically in end-to-end relation for each of two adjoining cylinders, each cylinder can be timed in this manner, independently of the other. Thus each cylinder can be timed properly to obtain maximum performance without in any way compromising with the timing of the adjoining cylinder.

How the above objects and advantages of our invention, as well as others not specifically referred to herein, are attained, will be more easily understood by reference to the following description and to the annexed drawings, in which:

Fig. 1 is a fragmentary vertical section through a typical internal combustion engine constructed according to our invention;

Fig. 2 is an enlarged fragmentary horizontal section on line 2-2 of Fig. l showing two fixed r shafts upon which rocker levers are mounted, the two shafts being mounted in a single housing upon the cylinder block;

Fig. 3 is a fragmentary vertical section on line 3,-3 of Fig. 2 showing the range of movement of a rocker lever with respect to the cam shaft as a result of rotation of the eccentric bearing; and

Fig. 4 is a fragmentary vertical section on line 4--4 of Fig. 2 showing a form of locking means employed at one end of the fixed shaft to hold it in a selected rotational position.

Fig. 1 is a vertical cross section through a typical Diesel engine, and shows a crank shaft l which is driven by a plurality of connecting rods Il attached to cranks I2 on the crank shaft. Each connecting rod Il is attached to a piston I4 which reciprocates within a cylinder I. The other cylinders and positions are similar to the one shown; For ease of construction, we prefer to make our invention in units for two cylinders, and we shall now describe an arrangement embodying this construction; but it will be realized that our invention is in no may limited thereto, nor is it limited to any particular number of cylinders.

At one side of and parallel tocrank shaft l is cam shaft 2|! which is driven from the crank shaft by the usual gear train. not shown. Cam shaft has a plurality of Iaxially spaced cams of suitable outline, there being shown in Fig. 1 a cam 2l for actuating the fuel injector. As cam shaft 20 rotates, it actuates a plurality of cam rocker levers 22 which are all generally similar to the one shown in Fig. 1 and are spaced lengthwise of cam shaft .20. Rocker levers 22 are mounted in groups of three at one end on bearings on a stationary shaft 24 and oscillate about the axis of the bearing; and at the other end of each rocker lever there is provided a roller follower 25 which engages a cam on shaft 20. As is conventional, certain of the cams, as cam 2|, operate the fuel injectors, while other cams 23 (Fig. 4) operate the valves. Though the two kinds of cams have different shapes, all cam rocker levers 22 are the same except that those for the injectors are made stronger.

As shown in Fig. 2, each rocker lever 22 has a socket 26 on its upper side near the inner or free end which receives the lower end of push rod 21 which is connectedat its upper end to top rocker arm 30 mounted on shaft 3l. Each rocker arm 30 is mounted to oscillate .about its bearing, on

lshaft 3l, which is intermediate the ends of the arm. One end of each rocker arm 30 is operatively connected to the stem of an exhaust or inlet valve (not shown) or to the stem of a fuel injector as shown in Fig. 1. Through this linkage just described, the upward motion of rocker levers 22 induced by cams 2l and 23 respectively raises push rods 27 to periodically cause the fuel injector 32 to introduce a quantity of fuel into the combustion chamber, or open a valve in the cylinder head above piston i6.

-Each bearing shaft 24 is made long enough to accommodate the three rocker levers for one cylinder; thus each shaft 26 is provided with two concentric bearings 3d and one intermediate eccentric bearing 33, as shown in Fig. 2.

The shafts 26 may be mounted upon the engine block in any convenient manner. In the drawings, two shafts Za are mounted in end-to-end relation within a single housing 3G which is bolted at 36a to the side of the engine block or frame slightly above and at one side of cam shaft 20. This construction is used because it is desired to have easy access to one end of each shaft 2t, and it is simple and economical to mount the shafts in units of two. As shown particularly in Fig. 2, each shaft 24 is rotatably mounted in housing 36 by means of simple journal bearings at each end of the shaft.

Housing 36 is open along one side, as shown in Fig. 1, except at its ends. For this reason, the inner adjacent ends of the two shafts 24 are held by split bearings, half of each of the two bearings being held in a single bearing block which can be tightened around the ends of shafts 24 by means of bolts 31. At their outer ends, housings 36 completely surrounds shafts 24, which. t inside a split bushing 33 which forms the bearing for the shaft. Each shaft 24 is provided with some means by which it can be engaged by a wrench or the like to rotatevthe shaft about its longitudinal axis. For this purpose, we have provided the outer. end of each shaft 24 with a hexagonal head 40 adapted to receive a standard socket wrench or the like. This hexagonal head is normally covered by cap 4| screwed into the open end of the housing, but which may be removed to provide access to the shaft.

turned to a selected position in order to obtain the proper adjustment of the injector rocker.

lever that it requires means to hold it in the adjusted position. For this purpose, any suitable locking means can be provided. At the inner end of the shaft, such locking action is supplied by tightening bolts 31 to clamp the end of the shaft in the bearings. At the other end of the shaft, frlctional locking means is provided by plug 42 which engages split sleeve 38 in order to compress the sleeve and clamp it around the end of the shaft. This locking action of plug l2 is controlled by set screw. 44 threaded into the housing. Set screw 44 may be turned by a socket wrench to advance or retract plug 42 and thus clamp or release the fixed shaft.

From the foregoing description of the construction of our invention, it will be evident that, by rotating a shaft 24 and its eccentric bearing 33, the fuel injector rocker arm 22 may be moved in a substantially longitudinal direction. The range of this movement is equal to twice the eccentricity of axis 33a of bearing 33, as shown in Fig. 3 in which the rocker arm is shown in the fully advanced position by full lines and in fully retracted position by dot-dash lines. 'Ihis longitudinal movement of the rocker arm changes the point in its revolution at which cam 2| commences to lift the free end of the rocker arm. In other words, this adjustment in position of the rocker arm makes it possible to regulate the angular position of the cam shaft at which the fuel injector is operated, thus timing the fuel in- `iection with respect to the revolution of the crank shaft of the engine.

This timing is accomplished in a very simple manner, after all of the parts of the engine have been assembled, merely by turning the shaft 24 for each cylinder until proper timing for each cylinder has been obtained. The proper adjusted position of shaft 24 is then maintained by tightening bolts 31 and set s crews 44 to clamp the ends of shafts 24, locking them in the adjusted positions. This timing operation can be carried out simply and in a relatively short time as it does not require any dismantling or reassembly of parts of the engine during the timing procedure. Each cylinder is timed independently of every other cylinder so that each cylinder operates under conditions of maximum performance.

Having described a preferred embodiment of our invention, it will be evident that various changes may be made in the arrangement and construction of the various parts without departing from the spirit and scope of our invention; and consequently we wish it to be understood that the foregoing description is considered illustrative of, rather than restrictive upon, the appended claims.

We claim:

1. In an internal combustion engine, the combination comprising: a rotatable cam shaft; a stationary shaft having two concentric bearings and a third bearing intermediate the first two, the third bearing having its axis eccentric with respect to the other bearings and the axis about which said shaft can be turned; a rocker lever mounted on each of the bearings and oscillated by the cam shaft; a push rod reciprocated by each of the rocker levers; and mounting means for said stationary shaft in which the shaft can be turned to selected positions about the*I axis of said concentric bearings, in order to shift said third rocker lever with respect to the cam shaft substantially longitudinal of said rocker lever, the other two rocker levers remaining unchanged in position when the third one is shifted.

2. In an internal combustion engine, the combination comprising: two cylinders each having a fuel injector; a pair of stationary shafts concentrically mounted in end-to-end relation, one at each cylinder; mounting means for the stationary shafts in which each shaft can be turned about the shaft axis to selected positions; a bearing on each stationary shaft having its axis eccentric to the shaft axis; a rotatable cam shaft; a plurality of rocker levers oscillated by the cam shaft and mounted one on each of the bearings on the stationary shaft; and a plurality of push rods, each reciprocated by one of the rocker shafts and operatively connected to one of the injectors; whereby the rocker lever associated with one cylinder can be shifted relative to the cam shaft in a direction substantially longitudinal of the rocker lever and independently of the rocker lever associated with the other cylinder to permit independent timing of the cylinders.

3. In an internal combustion engine as in claim 2, the combination that also includes locking means for each of the fixed shafts adapted to lock the shafts in selected rotational positions.

4. In an internal combustion engine as in claim 2, the combination that also includes: a second bearing on each stationary shaft concentric with the shaft axis; a second rocker lever for each cylinder mounted on each said second bearing and oscillated by the cam shaft; and a push rod reciprocated by each of said second rocker levers and operatively connected to a valve for a cylinder; said second rocker lever remaining unchanged in position when the first mentioned rocker lever on the same shaft is shifted longitudinally by rotation of the stationary shaft.

. DONALD R. BENNETT.

PAT BENNETT. RICHARD C. YOUNG.

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

UNITED STATES PATENTS Number Name Date 1,509,262 Royce Sept. 23, 1924 1,799,549 Evans Apr. 7, 1931 1,936,653 Almen Nov. 28, 1933 2,218,575 Griswold Oct. 22, 1940 FOREIGN PATENTS Number Country Date 486,191 Great Britain May 31, 1938