US 1265799 A
Description (OCR text may contain errors)
INSECTION 0F FUEL IN INTERNAL comausnow ENGINES.
APPLICATION FILED DEC. 2 1916. m fififiwa Patented May 14, 1918.
J MOKECHNIE, OF BABROW-IN-FURNESS, ENGLAND, ASSIGNOR TO VICKEBS LIMITED, OF WESTMINSTER, ENGLAND. 1
INJECTION 0F FUEL 1N INTERNAL-COMBUSTION ENGINES.
Application filed December 2, 1916.
To all whom it may concern:
Be it known that I, JAMES McKncnNm, a subject of the King of Great Britain, residing at Naval Construction Works, Barrow-in-Furness, in the county of Lancaster, England, have invented certain new and useful Improvements in or Relating to the Injection of Fuel in Internal-Combustion Engines, of which the following is a specivalve lever controlling the fuel injection is' operated by a cam the outline of which is so formed with relation to the path given by variation of the lever adjustment to the extremity of the lever that, for all clearances between the cam and lever and resulting variation in duration of fuel injection and engine power, the valve is timed to'open at the correct point at which injection should take place, without the introduction of special timing mechanism.- For this purpose the displacement of the lever for varying the fuel injection must be so chosen that a cam surface giving the correct timing for the variable speed and quantity of fuel is one of practicable form. r
A convenient method of adjusting the lever is to mount its fulcrum upon an eccentric partially rotatable so as to move the cam roller at the end of the lever toward or away from the cam and also usually to'displace it forwardly or rearwardly of the cam.
It has not hitherto been realized that a lever adjustment and the cam outline could be so related as togive the best timing of the .valve opening for all variations in engine power, but it is now found that by suitably choosing the size of the eccentric upon which the fuel lever fulcrum is mounted, the direction of partial rotation of the eccentric and the portion of the path of the eccentric during which regulation of the fuel valve is effected, the necessary movement of the fuel valve lever roller away from the cam cm be accomplished by any desired movement- Specification of Letters Patent.
Patented May 14:, 1918.
Serial No. 134,642. i
of the lever roller in or against the direction of rotation of the cam, and it is thus possible to obtain the required opening and closing of i the fuel valve at all adjustments without departing to any material extent from the cam profile most suitable for any particular duty of the engine.
The following edge of the cam is of course shaped in accordance with the form of the leading edge to give the proper duration of injection for all adjustments of the valve lever. This duration in an engine using mechanical injection and fuel supplied at constantpressure (for example by a battery of pumps passing any surplus fuel through a relief valve) will determine the charge of fuel at each firing stroke and will therefore depend upon the purpose of the engine. Thus in a marine engine of this type the angle of duration for a given reduced charge will, owing to the greater time of opening at lower speed, be less than in a constant speed dynamo engine. In an engine in which mechanical injection is used and a measured quantity of fuel is supplied at each firing stroke the angle of duration of opening will be so arranged that the spraying pressure is maintained at a high level even at low powers of the engine. In an engine using compressed air for the pulverization and spraying of the fuel the reduction of duration will be such as to prevent wastage of air owing to the valve remainin open longer ghap is necessary for the in ection of the The partial rotation of the eccentrically mounted fulcrum bearing of the fuel valve lever may be effected simultaneously with thecontrol of the fuel pump. Thus in a constant speed engine with a surplus fuel ing the two adjusting-gears, be made to give to'the injection valve the correct functionsfor the power as determined by the quantitydelivered by the fuel pump. For this purpose, we may mechanically operate the suction valve of'the pump by means of acam and adjustable lever with variable clearance on the lines described above for the injection valve lever. The displacement of the lever and the cam profile will in this case he so correlated that the suction valve may open early in the suction stroke or the pump at all adjustments and will close, according to the adjustment, at any point within the desired range of the delivery strolre of the pump a suiiicient lift of the valve being given at all adjustments.
in order that the said invention may he clearly understood and readily carried into efiect the same will he described more fully with reference to the accompanying drawings in which i urc 1 shows the application of the invention to the fuel injection valve operating devic of a constant speed internal combustion engine such as a dynamo engine,
Fl 2 shows the application of the i ention t 11 fuel injection valve operatin levice of a va iahle speed engine such as a marine engine 3 shows the application of the invention to the gear operating the suction i of the high pressure fuel pump an internal combustion engine; and
Fig. i is an enlarged view of shown in 3.
A is the earn shaft oi the engine upon which are mounted the injection valve cares U or C" and, 1 igs. 3 and 1-, the pump earn C is the valve spindle of the fuel injeca detail tion valves is the injection valve operating lever mounted on the eccentric or crank ll of the fulcrum pin l which can he partly rotated about its center and so move the center 72, of the eccentric The lever oscillates about this center it and, as the tulcruin pin is partly rotated, the eccentric cener it e ves in are about the pin ceni the cam roller on the end of the revolving about its center 6. g
lever shows the position at which the valve end of the lever touches the valve spindle when the valve is closed. it is the center of the eccentric H in maximum power position and c is the corresponding clearance hetween the oller and cam C l} or cani 2). q
Referring to Fig. 1., which shows the application of the invention to a constant speed engine in which it is desirable to adl u el at an early stage at all ranges of power the angle a. is the duration oi opening of the injection valve when the center of the eccentric H is in its maximum power position 7;. Upon partial rotation of the tulcruntF in a direction which causes the roller D to move opposite to the direction of motion of the earn C, the center it moves in an arc to, say, position it, causing both tangential and radial displacement of th roller in respe to the path of coin G position g of the valve end of the lever E remaining the same, that is, the valve is still closed), so that the center 2 of the roller D moves to the position 8, increasing the clearance loctween the cam C and the roller D to c. The duration of opening of the injection valve is now given by the angle a. @wing to the radial component 6 a of the displacement of the roller D which now works on the higher part of the cam C, the opening of the fuel valve is delayed by an amount represented h v the angle 7) between the points 6 and e 6 losing the center ot a circle of the same diameter as D and touch ing the circle of clearance c and the cam Q. But in moving from center a to center 6 the roller D has had imparted to it a tangential or angular displacement Z) partly conipensating for the delay in the opening of the fuel valve due to the roller working on the higher part of the cam. The net delay in the opening oi the valve is therefore the small angle represented by Z '-b, i. c. the angle subtended at the center of the cam shaft by the distance e"-e the extreme case in which the opening the fuel valve has to take place at the same point for all powers the path through which the center of the roller D is moved by the partial rotation of the pin F would be made to follow as closely as possible the contour of the leading face of the cam Q making the angle a' a zero. This may in certain cases entail inconvenient proportions of the eccentric H and in order to avoid this the leading edge of the cam may he made as steep as practicable so as to reduce the delay in opening of the fuel valve due to the roller worlringon the higher part of the cam. ln practice a slight retardation of the admission of fuel is desirable at reduced powers and this retardation is efiected by gradually sloping the leading edge of the cam C as shown in l.
The position a shows the center of the roller l) for the cut out position 72, of the eccentric H when the roller is quite clear of the cam Q Referring Fin. 2, which shows the application oi the invention to a variable speed engine in which as the power fails it is desirable to retard the fuel injection to considerably greater extent than in a conspeed engine, the angle a is the duraticn cl" opening-of the fuel injection valve when the center of the eccentric H is in its maximum power position 7L. Upon partial rotation of the fulcrum pin F, in a direction, such that the roller D moves in the same direction as the cam C, the center 72 moves to, say position if. This causes both a tangential and radial displacement of the roller l) relatively to the path of the cam C (the no sition g the valve end of the lever iei the saine that is the valve is still closed), the center of the roller D moving to the position 6 increasing the clearance 0 between the cam C and the roller D to 0 so that the duration of opening of the fuel injection valve becomes a owing to the radial displacement 6-6 of the roller D, which now works on the higher part of the cam C, and, due to this radial displacement only, the opening of the fuel valve is delayed by an amount represented by the angle 6 extending from e to e, a being the center of a circle of the same diameter as D and touching the circle of clearance c and the cam C. But in moving from the center 6 to center 6 the roller D has had imparted to it a tangential displacement b so that the timing of the opening of the fuel injection valve is delayed by this amount in addition to the delay due to the roller working on the higher part of the cam. The total delay in opening is therefore represented by a the angle b b It is evident that by suitably choosin the eccentricity of the eccentric or crank the direction of partial rotation of the fulcrum pin F during regulation and the mean position of the line f, h, it is possible to give, during the desired radial motion of the center 6, a tangential motion to the lever E of any desired amount in either direction, so that with a cam of practicable shape it is possible at all powers to obtain a close approximation to the desired point of opening of the fuel valve.
The path during regulation of the roller D and the leading edge of the cam C or C having been designed conjointly to obtain the required variation of timing of the first admission of fuel at various powers, the following edge of the cam is arranged relatively to the leading edge so that the angle of duration a (Fig, 1) or a (Fig. 2) will, in an engine arranged for mechanical injection of fuel at constant pressure, correctly determine the quantity of fuel admitted at each firing stroke, or, alternatively, will, in an engine arranged with fuel measuring pumps, maintain the injection pressure at a high level at all powers. In a constant speed engine the angle of duration of injection will obviously be greater for a given power than in, say, a marine engine.
In carrying the invention into effect it will be necessary to insure that the practical area for flow through the injection valve is normally considerably greater than the practical area through the pulverizing orifices, as is usual, otherwise at intermediate powers there will occur undue restriction before the fuel reaches the pulverizer, thus affecting the spraying of the fuel. At very low powers partial throttling by the injection valve may be adopted.
Fig. 3 shows the invention arranged for the control of a pump supplying high pres &
sure fuel oil, where separate fuel pumps are fitted to each cylinder, the control to be effected simultaneously with, and at all adjust-ments of, the fuel injection valve as already set forth.
P is the fuel oil pump, with suction port S, and suction valve V, which is controlled by the cam C on the cam shaft A through the cam roller R on the end of the lever L and the push rod 1). This push rod '2; keeps the lever L hard up to the cam C by means of the spring 12 through the guide '0'. Y is the fuel injection valve body in the cylinder cover Z, the fuel oil being delivered from the pump P to thefuel injection valve Y by means of the pipe 0, in which may be fitted a pressure accumulator T. M is the hand or governor controlled rock shaft carrying the eccentric N upon which the lover L is mounted. Upon this shaft is also mounted the lever Z controlling the adjustment of the fuel injection valve Y through the link Z and the lever Z on the eccentric fulcrum pin F. V
Fig. at is an enlarged'view of part of the cam C and the roller R on the end of the lever L. The cam C is shown just opening the suction valve V when the rock-shaft M is in its maximum power posit-ion, and the plunger p of the fuel pump P, which is driven from the cam shaft A by an eccentric X, is just commencing to ascend on its suction stroke, so that n is the position of the center of the eccentric N when it is the position of the center of the eccentric H, and r is the position of the center of the roller R. Upon the rock-shaft M being partly rotated so as to bring the center it of the eccentric H to say hfthe center n of the eccentric N moves in an are about the center of the rockshaft M to the position it, and in doing so moves the lever L so as to displace the roller R both tangentially and radially. relatively to the path of the cam C the point 9 of the lever L remaining in the same position throughout the movement, so that the center r of the roller R takes up the position 9" shown in Fig. 4. The angular displacement is shown at b and this is so proportioned in conjunction with the leading or opening edge of the cam C that the valve V opens at an early point in the suction stroke of the pump at all adjustments.
The radial displacement of the roller R causes the valve to open with more or less lift according to the direction of displace.
ment, and in the position 7 the valve obtains its minimum lift Whilein position r it remains completely open, corresponding to the cut-out position.
The cam C has its remaining contour so formed that the suction valve V is held open till the downward stroke of the plunger p begins and then is allowed to close, the point of closing, depending upon the position of the center of the eccentric ll, being represented by the angular positions (3;, Q the positions n, n at, of the said center The curve of the closing edge of the cam may he errange so that the efiective discharge of the pump bears any desired ratio to the duration of opening of the valve It is thus possible to maintain it high spraypressure at all powers.
l fiat I claim and desire to secure by Let-= ters Patent is 1. Fuel injecting mechanism for internal combustion engines, comprising an injection valve, a valve lever, a lever operating cam, and an adjustable eccentric fulcrum for the said lever, so positioned that its path of ad" justinent is approximately tangential to the cam and causes hot-h radial and tangential adjustment of the cam end of the lever, outline of the can being so formed with re lation to the path of adjustment of the lever end that correct timing of the point at which the valve opens is obtained for ell adjustments,
2, Fuel injecting mechanism for internal combustion engines, comprising an injection valve, avalve lever, a lever operating cani and an adjustable fulcrum for the lever so positioned that on adjusting the fulcrum for cover regulation the cam end 0" the lever following ed e of the cam,
moves along a pa suhstantie iv the contour the J 2-7 where the op diiierent positions of the engine strolls for lever.
53. Fuel injecting mechanism for internal combustion engines, comprising an injection valve, an adjustable valve lever, a lever operating cam having the outline of its leading surface so related the path or" adjustvalve, a valve lever, an adjustable eccentric v fulcrum on which the said lever is mounted, a lever operating esin having the outline of its leading surface so related to the path of adjustment of the lever as to time the valve opening for all adjustments of the lever, a fuel pump including a suction valve, a suction valve cain, cam lever operating the suction valve, adj ustahle eccentric fulcrum for the said cain lever, and an open etive connection between the two adjustable tulcrums by which simultaneous adjustment of the two lovers is effected.
In testimony whereof, l hereto ai'fin my signature,