US1334268A - Valve-gear for internal-combustion engines - Google Patents

Description

R. P. DOXFORD AND K. 0. KELLER VALVE GEAR FOR INTERNAL COMBUSTION ENGINES.

Patented Mar. 16, 1920.

APPLICATION FILED DECJZO, 191?.

R. PLDOXFORD'AND K. O. KELLER.

VALVE GEAR FOR INTERNAL COMBUSTION ENGINES. AEPLICATION FILED DEC. 20, 1917.

Patented Mar.16,1920.

3 SHEETS-SHEET 2.

R. P. DOXFORD AND K. OQKELLER. VALVE GEAR FOR INTERNAL COMBUSTION ENGINES.

APPLICATION FILED DEC. 20, I917. I

' Patented Mar. 16, 1920.

3 SHEEIS-SHEET 3.

Wlbzesses 3 (1 f wv'fiuwm I UNITED STATES PATENT OFFICE.

ROBERT P. DOXFORD AND KARL OTTO KELLER, OF SUNDEBLAND, ENGLAND.

VALVE-GEAR FOB. INTERNAL-COMBUSTION ENGINES.

Specification of Letters Patent.

Patented Mar. 16, 1920.

T 0 all whom it may concern:

Be it known that we, ROBERT PILE Dox- FORD, a subject of the King of England, and KARL OTTO KELLER, a citizen of Switzerland, both residing at Sunderland, in the county of Durham, England, have invented certain new and useful Improvements in Valve-Gears for Internal-Combustion Engines, of which the following is a specification.

This invention relates to valve-operating gears that are employed for the fuel-injection valves of internal-combustion engines employing mechanical injection, when the action of the fuel-delivering device controlling the amount of fuel-oil to be sprayed into the cylinder is to be altered whenever a change in the speed of the engine, or a change in its power, or in both, is desired.

In some such engines it has been proposed to control, by varying the discharge from the fuel-pump, the amount of fuel-oil injected into the cylinder, the requisite oilprcssure necessary for the mechanical atomization having been obtained by a springloadcd automatic valve. In such cases difficulties arose at light loads owing to the smallness of the amount of fuel-oil to be pumped for each explosion stroke of the euine. g To overcome this difficulty it was proposed to control, by mechanically varying the action of a fuel-injection valve, the amount of fuel oil to be injected. This was done by inter-posing between the valve and its opcratingcam, a single lever pivoted on an adjustable eccentric employed as a pivotpin. The cam actuated one end of the lever and the injection needlevalve was actuated by the other end of the same lever. The ac tion of the injection needle-valve was varied in this device by shifting the eccentric pin through a small angle, to shift the leverfulcrum and with itthe lever in relation to the cam. Difficulties arose with this construction in arranging for the desired lifts and timings of the needle-valve; because al though a cam and single lever, relatively adjustable as described, could be made to ive a lift and timing suitable for what might be termed a normal operation of the valve (say for full load), yet that cam being necessarily shaped to suit such normal operation imposed limitations when attempts were made to obtain the desired other lifts and timings by relative adjustment'between the same cam and the single lever.

The present invention concerns an improvement whereby, with the aid of a combination of two levers each receiving, so long as the distribution is not to be altered, a simple oscillatory motion on its fulcrum, one fulcrum and lever receiving a motion of translation at only such times as the distribution is to be changed, and a modifying-- cam between the levers, the lift and timings of the injection needle-valve can be made such as to give the best results at all loads, either in an engine with constant speed or in one with variable speed.

In the accompanying drawings- Figure 1 is a side elevation showing two injection-valves of one cylinderlof an engine and devices whereby they are operated according to the present invention;

Fig. 2 is a view generally similar to Fig. 1 of an alternative construction hereinafter particularly described.

Fig. 3 is a part side elevation of the apparatus according to Fig. 1 with the front valve-operating lever broken away, and

Fig. 4 is a corresponding View of the apparatus according to Fig. 2.

Like reference-letters indicate like parts throughout the drawings.

With reference first to Fig. 1, the construction comprises the combination with the rotatable cam RC and a rocking-lever 1 pivoted on an adjustable fulcrum F and simply rocked by the rotatable cam lever receiving any translatory motion therefrom, of a second lever 2 placed between the rocking lever and the fuel-valve FV together with a cam MG carried on the second lever. The cam MC may be termed a complementaryor modifying-cam, and it is so shapeo that in all the positions into which the rocking-lever is adjustable in relation to the second lever (and a series of such positions into which the roller R and, correspondingly, the left-hand end of the lever I carry- I mg it, can be shifted by such adjustment of the rocking-lever, when the distribution is to be altered, is shown by the chain-lined circles R R R B), it causes the motion imparted by the rotatable cam RC through the rocking-lever 1 to the "second lever 2 to be corrected or modified; thus the motions imparted by the second lever 2 to the valve FV are not limited as they would be in a combination of the rotatable cam RC With a solitary rocking-lever such as 1, and consequently can be those which are appropriate for the various lifts and timings desired. At the same time greater freedom can be exercised in the design of the rotat able cam RC than when a single adjustable lever was, as hereinbefore described, the only operative intermediary between the rotary cam and the needle-valve FV A convenient arrangement of the complementaryor modifying-cam MC is one in which it lies, as shown, along the righthand end of the second lever 2 and determines the form of the path in which the contiguous (left-hand) end of the rockinglever l is moved alongit in the adjustment of the adjustable fulcrum F, i. c. the path in which. the circles R R R R R appear, for the spring S keeps the roller against the underface of the cam MC during this adjustment.

This arrangement is particularly adapted for use in reversing engines. The modifying-cam MC shown in Fig. l is virtually a pair of cams, for the left-hand end of the cam in the drawing is the ahead cam inasmuch as it is so shaped that it will be given maximum movement, effecting a maximum opening of the valve FV for running in one direction, 1?. e. ahead when the roller R is under its left-hand end, the amount of this opening gradually diminishing to m'l as the roller R is moved from the position in which it is shown in full lines into the position indicated by the chainline circle R Theright-hand end of the cam MC in the drawing is the astern cam inasmuch as it is so shaped that it will be given maximum movement, effecting a maximum open ing of the valve FV for running in the other direction, 2'. e. astern when the roller R is under its right-hand end, the amount of this asternopening gradually diminishing to m'l as the roller moves from the position shown by the circle R into the position shown by the circle R".

The rightand left-hand lower faces of the cam MC are joined by a neutral or straight portion as shown, and in that portion of the adjustment of the rocking-lever 1 which carries the roller R from the position B through the position R into the position R and vice versa the lever will be in a neutral position in which it will not be actuated by the rotatable cam RC. Thus, by this employment of the modifying-cam in virtual pairs, a continuous adjustment, when the distribution is to be altered, of the rockinglever l by the shift of its adjustable fulcrum F can cause it to pass from operative relationship with the ahead cam through a neutral position into operative relation ship with the astern cam. lVhen reversal of the engine is to take place and this change of operative relationship is to be effected, the fulcrum pin F carried by the crank F will be shifted in the arc of a circle by rock- 'ing the am F it will be connected with the manually operating gear in the case of a marine engine.

The second lever 2, which operates the injection needle-valve F V has for its own fulcrum a pin EP which has a small eccentricity in relation to the bearing B in which it is held, and it is used for the purpose of accurately making (in a manner well understood) what may be termed a fine adjustment of the lift imparted to the needlevalve FV by the second lever; this fine adjustment may be made while the engine is running. This pin is stationary except when it is being used to make on occasion this fine adjustment.

In Fig. 1 there is a second fuel-valve FV worked by a lever 2 similar to the lever 2 and having, like the latter, a modifyingcam upon it. This valve F V opens into the same cylinder as the valve Fl, an arrangement which is particularly convenient in an engine, such as a marine engine, required to run at a variable speed. In such an engine the power to be developed varies very greatly, and it is convenient to bring the fuel valves successively into, as well as out of, operation according to the increase and decrease, respectively, of speed and power. The modifying-cam for the lever 2 is concealed behind the cam MC of the lever 2 in Fig. 1, but is clearly shown in Fig. 3 in which the lever 2 is broken away. It is shaped like the cam MC except that its lower face is recessed, as shown at line HS. in order that the action of the lever 2 and of the corresponding fuel-valve FV may be out out in the movement of the roller R, consequent upon the adjustment of the fulcrum F in a change of distribution, at times different from those at which the action of the lever 2 is cut out. For example, in the movement of the roller R into the position R it will be clear of the recessed modifying-cam on the lever 52 before it is clear of the cam MC on the lever 2; similarly, in moving from the position through the position R and onward to the right, it will be operative upon the cam MC as soon as it arrives in the position R but it will not be operative upon the modifyingcani of the lever 2 until it has moved beyond the position R past the recess, toward the position R Thus, the cutting out of action of one fuel-injection valve FV is not effected until after the valve FV has been cut out, in moving from ahead to-' ward astern, and in continuing that movement past the neutral position the fuelvalve FV will be cut in again before the valve FV is cut in. And of course the two ends of the virtual duplex cams MC need not be identical in shape, for it may not be necessary to have so much fuel coming into the cylinder in astern running as is wanted for ahead running.

In the example illustrated in the drawing, both the levers 2 and 2 are operated by the same roller R carried on a single rockinglever; but each valve could be given its own rocking-lever 1.if desired.

In the construction illustrated in Fig. 2, the second levers 2 and 2 operate separate fuel-injection valves by means of the rods VH and VR respectively. The two second levers are both operated by a rocking-lever 1 and rotatable cam RC as in the former case, but the modifying-cam MC is singleended as the arrangement is intended for ahead running only, and in the successive positions R R into which the roller R passes in moving to the right from the position in which it is shown in the drawing, in a change of distribution, it will pass less and less lift to the fuel-valve until it arrives in such positions as R and R in which the fuel-valves will be out of action altogether. The modifying-cam on the second lever 2 in this figure is concealed behind the modifying-cam MC of the lever 2 but is clearly shown in Fig. 4 in which the lever 2 is broken away, and is slightly different in shape as is shown by the dotted line at I) (Fig. 2) so that the roller R in moving from the position in which it is shown in full lines toward the right with the lever 1 will begin to lessen the opening of the valve that is effected by the second lever 2 before it lessens the opening of the companion valve controlled by the lever 2.

It is to be understood that the adjustable pivots or fulcra F of the several rockinglevers such as 1 in Figs. 1 and 2 can all be actuated simultaneously by automatic or manual means when the distribution is to be changed; they may be constituted by small cranks, as shown at F on a shaft. lie the case of a stationary engine these cranks can be under the influence of the governor. The proportions of the respective rocking-levers 1 and intermediate levers 2 and the amounts of movement given to the respective pivots of the former may be arranged as desired, for the proportions of the levers l and 2 the cams MC and the adj ustments allotted to different valves need not be identical.

The complementaryor modifying-cams are applicable in the manner above described to engines running at constant speeds as Well as to engines in which the speeds are variable; but of course the lifts and timings for the valves in the former case and therefore the shapes of the cams, would be different from those which would be employed in the latter case.

hat we claim as our invention and desire to secure by Letters Patent is 1. In an internal combustion engine, the combination with a fuel-injection valve and a main cam for controlling the same, of an adjustable fulcrum piece, an operating lever mounted to rock about said fulcrum .piece and having one end which receives from the cam a motion which is only a simple rocking motion, and a valve lever mounted to rock about another fulcrum piece and operatively connected with said valve, one of said levers having a cam face coacting directly with and bearing immediately on the other lever and adapted to impart the rocking movement of the operating lever in modified form to the valve lever, substantially as described.

2. In an internal combustion engine, the combination with a fuel-injection valve and a main cam for controlling the same, of an adjustable fulcrum piece, an operating lever mounted to rock about said fulcrum piece and having one end which receives from the cam a motion which is only a simple rocking motion, and a valve lever mounted to rock about another fulcrum piece and operatively connected with said valve, one of said levers having a cam face co-acting directly with and bearing immediately on the other lever and adapted to impart the rocking movement of the operating lever in modified form to the valve lever, the said cam-face comprising an ahead portion at one end, and an astern portion at the other end, and an intermediate neutral portion between the two ends which are disposed one behind the other in the path in which the adjustable fulcrum piece adjusts the said operating lever, substantially as described.

3. In an internal combustion engine the combination with a plurality of fuel-injection valves and a main cam for controlling the same, of an adjustable fulcrum piece, an operating lever mounted to rock about the said fulcrum piece and normally adapted to be actuated by said main cam, and a plurality of valve levers. one of said valve levers being opcratively connected to each valve and each of said valve levers being mounted to rock about a fulcrum piece difplurality of cams being situated between the ferent from that of the operating lever, and names to this specification in the presence 10 a plurality of differently shaped cams, one of two subscribing Witnesses.

of said cams being appropriated to the opr eration of each of the valve levers, the said i E 7 ends of the valve levers and the eoacting \Vitnesses to the signature of Karl Otto part of the said operating lever, substan- Keller: tially as described. H. NIXON,

In testimony whereof We have signed our A. MrroHnNsEN.

Images