US2030844A - Valve operating mechanism for internal combustion engines - Google Patents

Description

1936- s. H. ATTWOOD 2,030,844

VALVE OPERATING MECHANISM FOR INTERNAL COMBUSTION ENGINES Filed Jan. 13, 1953 5 Sheets-Sheet l S. H. ATTWOOD VALVE OPERATING MECHANISM FOR INTERNAL COMBUSTION ENGINES Feb. 18 1936.

F led Jan 13 1933 5 Sheets-Sheet 2 Fig.&

Feb. 18, 1936. s. H. ATTWOOD 2,030,844

VALVE OPERATING MECHANISM FOR INTERNAL COMBUSTION ENGINES Filed Jan. 13, 1933 5 Sheets-Sheet 3 Feb. 18, 1936. s, H ATTWOOD VALVE QPERATING MECHANISM FOR INTERNAL COMBUSTION ENGINES 5 Shets-Sheet 4 Filed Jan. 13, 1935 Feb. 18, 1936. s, H, ATTWOOD VALVE OPERATING MECHANISM FOR INTERNAL COMBUSTION ENGINES SSheets-Sheet 5 Filed Jan. 13, 1933 Patented Feb. 18, 1936 Nl'iE STATES VALVE OPERATING MECHANISM FOR INTERNAL COMBUSTION ENGINES Stanley Herbert Attwood, Wolverhampton, England, assignor to Simms Motor Units Limited,

London, England Application January 13, 1933, Serial No. 651,612 In Great Britain January 18, 1932 17 Claims.

This invention is for improvements relating to valve operating mechanism for internal combustion engines, and more particularly to valve operating mechanism for the fuel injection valve and inlet and exhaust valves of live rail Diesel or compression ignition engines. The expression live rail is employed to define that type of compression ignition engine in which fuel is maintained at relatively high pressure, (for example 3 to 5 tons per square inch), and admission of fuel to the engine cylinders is effected through an injection nozzle controlled by a fuel valve.

The invention has for some of its objects to provide valve operating mechanism in which the period of opening of a valve, especially a fuel injection valve, may be effected during a much smaller angle of rotation of the crank shaft of the engine than has heretofore been found possible; to provide a mechanism for fuel injection valves which enables the period of opening of i the valve to be varied without effecting any alteration in the timing of the valve and vice versa; and to provide an automatic control which prevents the fuel injection valve from being maintained open during each cycle of operation of the engine for a period which would cause too great a quantity of fuel to be injected into the engine cylinder.

According to this invention there is provided a valve operating mechanism which comprises a pair of oscillatory cams, the actuation of both of which is necessary to operate the valve and therein one cam initiates and the other terminates the said operation.

Further, according to this invention there is provided an operating mechanism for a fuel injection valve of a live rail compression ignition engine which comprises a cam mechanism operable to actuate the valve and means operable to vary the timing of the instant of opening of the valve effected by said cam mechanism in a cycle of operation of the engine whilst the period of opening of the valve is maintained unaffected by said variations.

Again. according to this invention there is provided an operating mechanism for a fuel injec-.

tion valve of a live rail compression ignition engine, which comprises means arranged to be operatively controlled by an accelerator pedal, or like member, for varying the period of opening of the valve and means operable automatically to vary the maximum period of opening which may be effected by the pedal or the like in accordance with the engine speed, for the purpose described. The invention also consists in a valve operating mechanism which comprises an oscillatory cam arranged to open a valve in such a manner that J the fully open position of the valve coincides with the termination ofa movement of the cam in one direction during an oscillation thereof.

In order that the invention may be fully understood, reference is directed to the accompanying drawings, in which:--- 5 Figure 1 illustrates in vertical section the cylinder head of an internal combustion engine provided with a valve mechanism constructed in accordance with this invention;

Figure 2 is a plan of Figure 1 cover removed;

Figure 3 is a section of a detail on the line 3-3 of Figure 1;

Figure 4 is a vertical section of a portion of the engine illustrated in Figures 1 and 2 corresponding to a section on the line 44 of Fig-' ure 2;

Figure 5 is an end elevation of an engine embodying the valve mechanism illustrated in Figures 1 to 4 illustrating certain controls hereinafter described;

Figure 6 is a View at right angles to Figure 5;

Figure '7 is a plan of Figure 6;

Figure 8 illustrates a detail of a slow running control for the engine illustrated in Figures 1 to '7;

Figure 9 is a view similar to Figure 5, but illus trating a modification of the invention;

Figure 10 is a section on the line Ill-40 of Figure 9; Figure 11 illustrates a detail of Figure 10, but

with parts shown in different positions;

Figure 12 is a diagram illustrating the relationship of certain parts illustrated in Figures 9 to 11 hereinafter described;

Figures 13 to 16 are diagrams illustrating respectively different positons of the cams for the fuel valve of the engine illustrated in Figures 1 to 4 during a cycle of operation of the engine as hereinafter described, and

Figure 17 is a diagram showing the range of adjustment which may be obtained for the fuel valve both in respect of timing and period of opening as hereinafter described.

Referring to the drawings, the head I of one cylinder of a Diesel or compression ignition engine is illustrated which is provided with air inlet valves 2 and exhaust valves 3. Centrally at the cylinder head a fuel valve 4 is provided which in the example shown is constructed in accordance 5 with British Patent application No. 1429 of 1932. At the upper end of the fuel valve stem a doublearmed rocker 5 is pivotally mounted about a horiozntal axis disposed transverse to the rocker and with an upper is provided at each of its ends with a downwardly v directed curved shoe 6, which is concentrically arranged with respect to the axis of one of a pair of oscillatory shafts 1, 8. The shafts I, 8 extend along the top of the engine over all the cylinders thereof arranged in line and are rotatably mounted in a series of bearings, two of which are indicated at 9 in Figure 2. Hereinafter the shaft I will be referred to as the period shaft and the shaft 8 as the time shaft. The

shafts I, 8 are coupled together at one end by a f pair of helical gears II], I I and the gear III on.

the period shaft is slidable axially thereof ina manner hereinafter described to effect relative rotation between the two shafts; the gear I9 is shown in its normal position in Figure 7 and is slidable in the direction of the arrow a to effect rotation of the shaft 1 in a clockwise direction, Figure 1, by virtue of the helical form of' the gear teeth and the relative fixity of the gear I I in the axial and rotational directions; this direction of rotation of the shaft 1 has been generally in'-- dicated in the drawings by arrows b.

. Each fuel valve is arranged to be operated by a pair of oscillatory cams I2, I3 mounted respectively upon the shafts I, 8 and the active surface of each cam is constituted by a curved surface arranged concentrically with respect to the axis of the respective shaft I or 8 which forms the axis of oscillation of the cam. Each cam is arranged to act upon the respective shoe 6 to lift the adjacent end of the rocker 5: through the medium of a relatively small roller I4 which is carried in a slot, formed in an' annular lateral extension I5 of a collar I6 keyed to the respective shaft 1 or 8. It will be seen more particularly from Figure 3 that the extension I5 surrounds the respective cam I2 or I3. The point during the oscillation of either of the cams I2 or I3, at which the cam is effective to actuate the rocker 5, depends upon the position of the respective roller I4 longitudinally of the curved surface of the shoe 6 associated therewith, and this position of the roller may be varied by a partial rotation of the respective shaft I or 8 which carries the collar I6 and the roller I4 therewith. Whatever the operative position of the rollers I4 may be relatively to the respective shoes 6,. the thrust of the cams on the shoes will always be radial and clearances between the said cams, rollers and shoes will remain unaltered.

Each of the cams I2, I3 is formed integrally with one of a pair of eccentrics I1, t8, eachcoupled by a strap I9 and a connecting rod 25 to the strap 2I of one of a pair of eccentrics 22, 23

provided respectively upon rotatable shafts 24,

The shafts 24, 25 are arranged to be rotated at half the crank shaft speed of the engine by gearing generally indicated at 25a, Figure 5, in opposite directions as indicated by the arrows in Figure 4. The eccentric 22 is 52 out of effective phase with the eccentric 23, whilst the eccentric I1 is 42 out of. effective phase with the eccentric I8. The relative angular disposition of the eccentrics 22, 23, IT and I8 will be more clearly appreciated from the following particulars given ;at right angles to a line through the said axis and the axis of the shaft Twhil'e the eccentric 23 is retarded by an angle of 26 from a similar radial line drawn at right angles to a linethrough the axes of the shafts 25 and 8. The peak radial line of the eccentric I1 is advanced by an angle of 21 with reference to a radial line through the axis of the shaft I disposed at right angles to the line extending through the axes of the said shaft 1 and the shaft 24, while the radial peak line of the eccentric I8 is retarded by an angle of 21 from a similar radial line from the axis of the shaft 8 which is disposed at right angles to the line through the axes of the shafts 8 and 25. These particular angular displacements between the four eccentrics ensure the phase displacement between the cams I2 and I3 which causes the cam I2 to lead the cam I3 to a sufficient extent that during the inward movements of the cams towards one another the cam I2 will reach its inner reversing point and again return to itsroller I4 at a moment when a sufficient distance is still present between the cam I3 and its roller I4 to ensure that the cam I2 will completely pass its roller I 4 before the cam I3 reaches its roller. From this explanation it will be clear that the oscillatory motions of the cams I2 and I3 can be. readily produced by any convenient pair of mechanisms for converting rotary motion of the engine crank shaft into reciprocatory motion, such mechanisms being known in many forms and the eccentric mechanisms disclosed in the accompanying drawings being preferred as giving a very smooth and silent action. Whatever form of mechanism be used for oscillating the cams I2 and I3 the essential point is that one of' the cams, in the example the cam I2, shall lead the other cam, in the example the cam f3, by a sufficient amount to ensure that when the cams have passed their rollers in periods which overlap-as the cams move in one direction, one of the cams will reverse and reach its roller in the return motion while a sufiicient distance still remains between the second cam and its roller, due to the lag of the second cam which ensures that by the time the second cam reaches its roller the first cam will have passed its roller.

Thus the eccentrics 22, 23- as they rotate with the shafts 24, 25 eifect oscillatory motion of thecams I2 and I3, and the phasing of the cams above referred to ensures that the movement of the active surfaces of the cams towards one another in Figure 1 as indicated by the arrows c, d, ensures that the periods during which they pass their respective rollers I4 overlap one another in such a manner that they both act upon the rocker together although the timing when each cam begins and ceases to act and the period during which they are both active, determined by the amount of overlap above referred to, may be varied as hereinafter described. During the return movement of the cams away from one another in Figure 1 the cams pass their respective rollers I4 out of phase with one another in the manner above described, so that only one cam operates upon the rocker at a time, and the arrangement is such thatv the valve 4 is only open when both the cams I2, I3 raise the rocker 5. In one practical example, the cams I 2, I3 are arranged jointly to effect a raising of the valve 4 from its seat by .015 inches.

It will thus be appreciated that with the arrangement described the valve 4 is not raised from its seat during the return movement of the cams I2, I3 in the opposite directions to the arrows c, (1, Figure I, the rocker 5 being merely rocked idly about its pivot as each of the cams I2, I3 acts separately thereon.

The cams I2, I3 are also formed integrally with cams 26, 21, Figures 2 and 4, of which the cam 26 associated with the cam I2 is arranged to operate the inlet valve 2 through the medium of a rocker 28, whilst the cam 21 associated with the cam I3 is arranged to operate the exhaust valve 3 through the medium of a rocker 29. With the arrangement illustrated the end of an oscil latory movement of both the cams 26, 21 is arranged to coincide with the mid-point of opening of the respective inlet or exhaust valves and each of the cams 26 or 2! is arranged to produce the maximum lift of the respective valve at this point. In the drawings each cylinder is shown as being provided with duplicate inlet and exhaust valves, each pair being operated together through the medium of the rockers 28, 29. The cams 26, 21 need not be formed integrally with the respective cams I2, I3 but may be formed separately and operatively connected'in driving relationship with the latter cams. If desired, thecams 26, 21 may be driven by mechanism other than that which drives the cams I2, I3. Also the oscillatory motion of the cams I2, I3 and 26, 21 may be derived from cams in lieu of eccentrics such as 22, 23.

In the operation of the fuel valve by the cams I2, I3 the cam I2 first comes into operative association with its roller I4 and shoe 6 so that as soon as the cam I3 moves into the operative position to lift its roller I4 and shoe 6 the valve 4 is opened, and the point at which the cam I3 operates upon its roller I 4 controls the timing of the valve 4, and, therefore, the timing of the ignition for the engine cylinder of the said valve. Thus, movement of the roller I4 in one direction or the other about the axis of the timing shaft 8 controls the said timing for the respective engine cylinder.

After the cam I3 has moved into the operative position to raise the valve 4 the period during which the valve remains open depends upon overlap of the cams I2 and I3 as they pass their rollers I4 together and this is determined in the example illustrated by the length of the active surface of the cam I2 which is still required to travel past its roller I4 before the adjacent end of the rocker is allowed to fall and effect the closing of the valve 4 by the return spring 4o.

Thus, the longest period of opening of the valve 4 is obtained when the cam I2 has only just moved into the operative position as the cam I3 also moves into the operative position whilst the shortest period is produced when the cam I2 moves out of the operative position almost immediately after the cam I3 has moved into the operative position to open the valve. The period during which the valve 4 remains open is, therefore, arranged to be controlled by moving the roller I4 associated with the cam I2 about the axis of the period shaft I in one direction or the other in a manner hereinafter described.

It will also be appreciated from the above description that when an alteration in the timing of the valve 4 by means of a movement of the roller I4 associated with the cam I3 is effected,

it will also be necessary to effect a similar movement of the roller I4 associated with the cam I2 in order that the period of opening of the valve 4 may not be altered by an adjustment in the timing, and this is ensured by the coupling of the shafts I and 8 together by the helical gears I0, I I.

similar to those illustrated in Figure 1, in which both cams are acting upon the rocker 5 and the fuel valve 4 is raised from its seat so that injection of fuel into the engine cylinder is being effected; the cams I 2, I3 are shown at a point during their movement in the direction of the arrows c, d. In Figure 14 the cam I2 is in its innermost or extreme'clockwise position, so that the fuel valve 4 is closed whilst the cam I3 has not yet reached its innermost or extreme anticlockwise position. In Figure 15 the cam I2 is in a position during its return or anti-clockwise movement, in which it is about to lift the adjacent end of the rocker 5, but the cam I3 has only reached its innermost or extreme anti-clockwise position and is clear of its roller I4 so that the valve 4 remains closed whilst the cam I2 passes its roller I4; during this portion of the movement the cam 21 (not shown in Figure 15) is operating to open the exhaust valve which in the position of the parts illustrated is in the midpoint of its opening period. In Figure 16 the cam I2 is in its outermost or extreme anti-clockwise position whilst the cam I3 is in a position during its outward or clockwise movement in which it has just passed its roller I4 out of phase with the cam I2, so that the fuel valve 4 remains closed; this position of the cam I2 corresponds to the mid-point of the opening period of the inlet valve which is effected by the cam 26 (not shown in Figure 16). It is to be noted that the cams I2, I3 are arranged to act upon the rocker 5 during the more rapid portion of their oscillatory movements and thus enable the accurate control of the fuel valve to be most readily obtained. The cams 2B, 21 on the other hand, are brought into efiective operation to control the inlet and exhaust valves at the end of an oscillatory movement of the said cams which are then moving relatively slowly thus ensuring a minimum wear on the cams and rollers.

Before proceeding to describe the various mechanisms which are employed to move the roller I4 about the axes of the shafts I and 8 for the purpose of altering the timing and period of opening of the fuel valve 4 reference is directed to Figure 17, and the following table which shows the different positions which the rollers I4 occupy relatively to one another for various periods of opening of the valve 4 with different timings.

In Figure 17 the cams I2, I3 are shown in positions corresponding to those in which the fuel valve is about to be opened at top dead centre of the compression stroke and for a maximum possible period when the respective rollers I4 are in the positions A and A. Each of the successive alternative positions for different time and period represent a movement of the crank shaft of the engine through an angle of 20.

With the construction of cam mechanism for the fuel valve as above described the period of opening of the valve maybe effected efficiently within an angular range of the engine crank shaft from a maximum of 80 to a minimum of 3, giving a minimum period which is much smaller than anything previously attained which has usually been from 15 to 20 of the engine crank shaft. The maximum period may obviously be increased by suitable increase in the length of the active surface of the period cam l2 and time cam |3 to provide the necessary period of overlap of the cams.

In Figures 5, 6 and 7 an arrangement is illustrated in which the control of the time of opening of the valve 4 is effected by a governor of known construction generally indicated at 38, and

which is operatively connected to the timing shaft 8 by a link 3|, double- armed lever 32, 33, link 34 and an arm 35 carried by the end of the shaft 8. As the speed of the engine rises the governor operates automatically to rotate the shaft 8 in the direction of the arrow e, Figure 5, and thus the roller M of the timing cam |3 is moved in a clockwise direction in Figure 1, so that it is met by the leading edge of the cam [3 during its operative movement earlier in the cycle of operation of the engine and thus advances the time of opening of the fuel valve 4. This adjustment also effects the necessary counter clockwise adjustment of the roller I4 for the cam I2 through the medium of the gears I6, I l as hereinbefore described so that the period of opening of the valve remains unaltered. Alternatively, the advance in timing of the opening of the valve 4 may be effected by a manual control operatively connected to the time shaft 8 to enable the said shaft to be rotated in either direction.

The period during which the valve 4 is maintained open is controlled through the medium of a lever 36 which is carried by a pivotally mounted spindle 31 and is arranged to be operatively connected to an accelerator pedal, or other similar control for the internal combustion engine. The spindle 37 has a toothed sector 38 keyed thereto which is arranged in mesh with a series of annular rack teeth 39 formed upon an extension of the helical gear l6. ()scillatory movements of the lever 36 thus effect reciprocatory movements of the gear I8, whilst the annular form of the teeth 39 permits rotation of the gear l and rack 39 relatively to the sector 38, both during individual adjustment of the gear II] as it moves axially to control the period of opening of the fuel valve by a clockwise rotational movement of the said gear I8, Figure 5, relatively to the gear H, and as it is rotated with the shaft 8 and gear during an adjustment of the timing of the fuel valve.

To enable the slow running position of the period shaft 8 to be varied, the lever 36, Figure 8,,

is arranged to be limited in its extreme slowrunning position by a cam 36a provided upon a pivoted arm 3% which, in the case of the engine of a road vehicle, may be adjustable from a control situated on the dash board of the vehicle.

The amount of fuel injected into an engine cylinder operating upon the live rail principle depends solely upon the pressure of the fuel in the supply conduit and the period during which the injection valve is open, which latter is dependent not only upon the setting of the roller H! for the period cam |2 but upon the speed at which the engine is running, and therefore the operation of the accelerator pedal or other control for the period of opening of the fuel valve to give the normal maximum period of fuel injection whilst the engine is running at slow speeds is undesirable, because this clearly results in an injection of too great a quantity of fuel. To avoid this undesirable feature a construction of control mechanism is illustrated in Figures 9 to 12 in which a governor is employed to control the extent to which the period of opening of the fuel injection valves may be increased by the accelerator pedal or other control for any particular engine speed. The principle of this arrangement is such that during slow running of the engine the governor operates to reduce the amount of axial movement of the helical gear III for any given movement of the accelerator pedal or similar control. With the exception of this interconnection between the governor and the period control which is hereinafter described, the construction shown in Figures 9 to 11 is similar to that shown in Figures to '7, time shaft 8 being arranged under the control of the governor 30 and the accelerator control operatively connected to the gear ID of the period shaft 1. The various parts of the mechanism illustrated in Figures 9 to 12 have been indicated by the same reference numbers as the corresponding parts in Figures 5 to 7 where this is possible.

Referring to Figures 9 to 12 the spindle 3'! of the accelerator lever 36 has an arm 40 keyed thereto which is connected by a link 4| to one end of a rack 42 which is slidably mounted in a hollow arm 43 which forms an extension of the toothed sector 38 which is operatively connected to the annular rack teeth 39 hereinbefore described. When the rack 42 is in a position in which the link 4| is located in the position illustrated in Figure 10, oscillatory movements of the spindle 31 by means of the lever 36 produce minimum angular movements of the arm 43 and sector 38, whilst when the rack 42 and link 4| are in the positions indicated in Figure 11 such oscillatory movements of the spindle 31 produce maximum angular movements of the sector 38.

The arbour 44 of the sector 38 is provided With a hollow bore 45 into which the end of a rack 46 is arranged to extend. The rack 46 is slidably mounted in a guide 41 mounted upon the engine frame, and the teeth of the rack are arranged to mesh with the teeth of the rack 42, the teeth of both racks being disposed at an angle of 45 to the axes of the respective racks in the manner illustrated diagrammatically in Figure 12, so that movement of the rack 46 in the direction of the arrow 1 produces a movement of the rack 42 in an outward direction indicated by the arrow g in Figure 10. Normally, the racks 42 and 46 are in the positions illustrated in Figures 9, and 12.

The rack 46 is provided at its outer end with a series of annular rack teeth 48 arranged in mesh with a toothed sector 49 keyed to the time shaft 8. Thus, with the construction described, as the engine gains speed and the governor 30 operates to advance the timing of the point of opening of the fuel valve by clockwise rotation of the time shaft 8 the toothed sector 49 moves the rack 46 in the direction of the arrow f, whereby the rack 42 is moved in the direction of the arrow g and the link 4| therewith resulting in a progressively increased angular movement of the sector 38 relatively to the angular movements of the lever 36 with increase of engine speed as above described.

The invention thus provides a valve operating mechanism for an internal combustion engine in which the opening period of a valve may be effected during an angle of rotation of the crank shaft of the engine which is much smaller than has acsdskr heretofore been possible, and the mechanism is particularly free from variations in the clearances between the different operative members due either to strain or wear in the members themselves, variations in relative setting, or adjustment of the different members, or due to expansion or contraction of the parts of the mechanism with fluctuations in temperature owing to the relatively close assembly and concentric arrangement of the operative elements. Moreover, any slight errors in manufacture of the valve operating mechanism may readily be compensated when assembling the various parts; the collars It may, for example, be relatively adjusted around the shafts I and 8 before finally being keyed there to, so as to compensate any slight discrepancies between the various cams l2 and I3 and their settings as determined by their operative connections to the eccentrics 22, 23. Also, when the invention is applied to the operation of a fuel injection valve for a Diesel engine the timing of the opening of the valve may be varied without causing any alteration in the period of opening of the valve, alterations in timing being automatically compensated in the period control so that the period is maintained constant for any particular setting of the timing control. In addition, the invention provides an automatic control which prevents the injection of too great a quantity of fuel when the engine is running at relatively slow speeds.

It is to be understood that the invention may also be applied to the valve mechanism of twostroke cycle compression-ignition engines as well as to four-stroke cycle engines as above described, suitable alterations being made in the speed of operation of the cams in order to synchronize their action with the cycle of operation of the engine.

What I claim and desire to secure by Letters Patent of the United States is:

1. In a valve actuating mechanism, a pair of oscillatory cams, a follower for each of said cams, a valve actuating member operable to be effectively actuated by said cams and followers only when both said followers are actuated together by said earns, a driving element adapted to be continuously rotated, and a pair of mechanisms each adapted to convert rotary motion into reciprocatory motion and connected on the one hand in driven relationship to said driving element with a phase displacement with respect to one another and on the other hand to one of said cams to oscillate the same through predetermined phase displaced angles determined by the phase displacement of said mechanisms, said followers being so positioned in the paths of oscillatory movement of the respective cams that the periods of actuation of the followers by the cams overlap during movement of the cams in one direction of their respective oscillations and follow in succession without overlap during movement of the cams in the other respective directions due to the phase displacement between the cams.

2. In a valve actuating mechanism, a pair of oscillatory cams, a follower for each of said cams, a valve actuating member operable to be effectively actuated by said cams and followers only when both said followers are actuated together by said cams, a pair of crank devices coupled together with a predetermined phase displacement relatively to one another and adapted to be uniformly rotated, mechanisms operable to convert the rotary motion of each of said crank devices separately into oscillatory motion and each connecting one of said crank devices to one of said cams to oscillate the same through predetermined phase displaced angles, said followers being so positioned within the angles of movement of respective cams that the periods of actuation thereof by the cams overlap during movement of the cams in one direction of their respective oscillations and follow in succession without overlap during movement of the cams in the other respective directions. v

3. In a valve actuating mechanism, a pair of oscillatory cams, a follower for each of said cams, a valve actuating member operable to be efiectively actuated by said cams and followers only when both said followers are actuated together by said earns, a driving element adapted to be continuously rotated, a pair of driving eccentrics coupled to said driving element so as to be rotated thereby and displaced in phase with respect to one another, a pair of driven eccentrics each coupled by a link to one of said driving eccentrics so that said driven eccentrics are adapted to be oscillated by said driving eccentrics through angles of movement displaced out of phase with one another, each driven eccentric being coupled to one of said cams to oscillate the same and said followers being so positioned within the paths of movement of the respective cams that the periods of actuation thereof by the cams overlap during movement of the cams in one direction of their respective oscillations and follow in succession without overlap during movement of the cams in the other respective directions.

4.- In a valve actuating mechanism as claimed in claiml, the provision of means operable to displace the followers of the cams in unison around the paths of the respective cams in directions such that theextent of overlap in the actuation of the followers by the cams is not altered.

- 5. In' a valve'actuating mechanism as claimed in claim 1, the provision of means operable to displace one of the followers along the path of its camindependently of the other follower to vary the extent of overlap in the actuation of the two followers.

' 6. In a valve actuating mechanism as claimed in claim 1, the provision of means operable to displace the followers of the cams in unison around the axes of the respective cams in directions such that the extent of overlap in the actuation of the followers by the cams is not altered and means operable to displace one of said followers along the path of its cam independently of the other follower to vary the extent of overlap in the actuation of the two followers.

7. In a compression ignition internal combustion engine comprising at least one cylinder provided with a yieldingly controlled fuel injection valve and at least one air inlet valve and at least one exhaust'valve, the combination of an actuating mechanism as claimed in claim 1 adapted to actuate said fuel valve, with a pair of additional cams one being'adapted to be oscillated in unison with one of the oscillatory cams to actuate-said air inlet valve and-the other with the other oscillatory cam to actuate said exhaust valve, the fully-open position' of each of the said inlet andexhaust valves'coinciding with a terminal position in the oscillation of the respective additional cam, and means operable to displace at least one of the followers of the oscillatory cams along the path of movement of its cam.

8. In a valve actuating mechanism, a pair of oscillatory cams, a valve actuating member provided with a pair of surfaces, one associated with each cam and each of which is disposed parallel to the path of the peak of its associated cam, a roller disposed between each cam and surface to transfer the thrust of the cam to the valve actuating member, said member being operable to be effectively actuated only when both said rollers are actuated together by said cams, a driving element adapted to be continuously rotated, a pair of mechanisms each adapted to convert rotary motion into reciprocatory motion and connected on the one hand in driven relationship to said driving element with a phase displacement with respect to one another and on the other hand each to onerof said cams to oscillate the same through predetermined phase displaced angles determined by the phase displacement of said mechanisms, said rollers being so positioned in the paths of oscillatory movement of the respective cams that the periods of actuation of the rollers by the cams overlap during movement of the cams in one direction of their respective oscillations and follow in succession without overlap during movement of the cams in the other respective directions due to the phase displacement between the cams and a carrier member for at least one of said rollers, said carrier being movable to displace its roller about the axis of oscillation of the :cam. associated therewith and alter the position of the roller along the path of the said cam.

9. In a valve actuating mechanism, a pair of oscillatory cams, a valve actuating member provided with a pair of surfaces, one associated with each cam and each of which is disposed parallel to the path of the peak of its associated cam, a roller disposed between each cam and surface to transfer the thrust of the cam to the valve actuating member, said member being operable to be effectively actuated only when both said rollers are actuated together .by said cams, a driving element adapted to be continuously rotated. a pair of mechanisms each adapted to convert rotary motion into reciprocatory motion and con-v nected on the one hand in driven relationship to said driving element with a phase displacement with respect to one another and on the other hand each to one of said cams to oscillate the same through predetermined phase displaced angles determined by the phase displacement of said mechanisms, said rollers being so positioned in the paths of oscillatory movement of the respective cams that the periods of actuation of the rollers by the cams overlap during movement of the cams in one direction of their respective oscillations and follow in succession without overlap during movement of the cams in the other respective directions due to the phase dis placement between the cams, a carrier member for each of said rollers, said carriers being movable to displace their rollers about the axes of oscillation of the respective camsand alter the position of the rollers along-the paths of the cams, and a coupling device between said carriers to maintain the effective overlap of the cams on said rollers unaltered when one of the carriers is moved.

.0. In a valve actuating mechanism, a pair of oscillatory earns, a valve actuating member provided with a pair of surfaces, one associated with each cam and each of which is disposed parallel to the path of the peak of its associated cam, a roller disposed between each cam and surface to transfer the thrust of the cam to the valve actuating member, said member being operable to be effectively actuated only when both said rollers are actuated together by said cams, a

driving element adapted to be continuously rotated, a pair of mechanisms each adapted to convert rotary motion into reciprocatory motion and connected on the one hand in driven relationship to said driving element with a phase displacement with respect to one another and on the other hand each to one of said cams to oscillate the same through predetermined phase displaced angles determined by the phase displacement of said mechanisms, said rollers being so positioned in the paths of oscillatory movement of the respective cams that the periods of actuation of the rollers by the cams overlap during movement of the cams in one direction of their respective oscillations and follow in succession without overlap during movement of the cams in the other respective directions due to the phase displacement between the cams, a carrier for each of said rollers, said carriers being movable to displace said rollers about the axes of oscillation of the respective cams and alter the position of the rollers along the paths of the cams, and a coupling device between said carriers selectively operable to afford relative movement between said carriers to enable one carrier to displace its roller independently of the other and to afford simultaneous movement of both said carriers and rollers to maintain the effective overlap of the cams on the rollers unaltered.

11. In a valve actuating mechanism, a pair :of oscillatory cams, a valve actuating member provided with a pair of surfaces, one associated with each cam and each of which is disposed parallel to the path of the peak of its associated cam, a roller disposed between each cam and surface to transfer the thrust of the cam to the valve actuating member, said member being operable to be effectively actuated only when both said rollers are actuated together by said cams, a driving element adapted to be continuously rotated, a pair of mechanisms each adapted to convert rotary motion into reciproc'atory motion and connected on the one hand in driven relationship to said driving element with a phase displacement with respect to one another and on the other hand to one of said cams to oscillate the same through predetermined phase displaced angles determined by the phase displacement of said mechanisms, said rollers being so positioned in the paths of oscillatory movement of the respective cams that the periods of actuation of the rollers by the cams overlap during movement of the cams in one direction of their respective oscillations and follow in succession without overlap during movement of the cams in the other respective directions due to the phase displacement between the cams, a cage rotatably mounted about the axis of oscillation of each of said cams, each cage embracing the roller of the cam co-axial with said cage and adapted to move said roller round the axis of said cam, means rotatively coupling said cages together including a pair of gears and means for rotatably moving said gears.

12. In a valve actuating mechanism, a pair of oscillatory cams, a valve actuating member provided with a pair of surfaces, one associated with each cam and each of which is disposed parallel to the path of the peak of its associated cam, a roller disposed between each cam and surface to transfer the thrust of the cam to the valve actuating member, said memberv being operable to be effectively actuated only when both said rollers are actuated together by said cams, a driving element adapted to be continuously rotated, a pair of mechanisms each adapted to convert rotary motion into reciprocatory motion and connected on the one hand in driven relationship to said driving element with a phase displacement with respect to one another and on the other hand to one of -said cams to oscillate the same through predetermined phase displaced angles determined by the phase displacement of said mechanisms, said rollers being so positioned in the paths of oscillatory movement of the respective cams that the periods of actuation of the rollers by the cams overlap during movement of the cams in one direction of their respective oscillations and follow in succession without overlap during movement of the cams in the other respective directions due to the phase displacement between the cams, a cage rotatively mounted about the axis of oscillation of each of said cams, each cage embracing the roller of the cam coaxial with said cage and adapted to move said roller about the axis of said cam, means including a pair of helical gears rotatively coupling said cages together, means for rotatively moving said gears and means for move ing one helical gear axially with respect to the other.

13. In an internal combustion engine a crank shaft, a fuel injection valve, a pair of oscillatory cams, one associated with each cam and each of which is disposed parallel to the path of the peak of its associated cam, a roller disposed between each cam and surface to transfer the thrust of the cam to the valve actuating member, said member being operable to be effectively actuated only when both said rollers are actuated together by said cams, a driving element adapted to be continuously rotated, a pair of mechanisms each adapted to convert rotary motion into reciprocatory motion and connected on the one hand in driven relationship to said driving element with V a phase displacement with respect to one another and on the other hand to one of said cams to oscillate the same through predetermined phase displaced angles determined by the phase displacement of said mechanisms, said rollers being so positioned in the paths of oscillatory movement of the respective cams that the periods of actuation of the rollers by the cams overlap during movement of the cams in one direction of their respective oscillations and follow in succession without overlap during movement of the cams in the other respective directions due to the phase displacement between the cams, a cage rotatively mounted about the axis of oscillation of each of said cams, each cage embracing the roller of the cam coax al therewith and adapted to move said roller about the axis of said cam, means including a pair of helical gears rotatively coupling said cages, one of said gears being axially displaceable, a lever mechanism operatively connected to said axially displaceable helical gear to effect axial displacement thereof, a displaceable fulcrum device operable to vary the effectiveleverage of said mechanism and a governor responsive to the speed of said crank shaft of the engine and operatively connected to the displaceable fulcrum device to reduce the said leverage during a predetermined lower speed range of the crank shaft.

14. In an internal combustion engine a crank shaft, a fuel injection valve, a pair of oscillatory cams, a follower for each of said cams, a valve actuating member operable to be eifectively actuated by said cams and followers only when both said followers are actuated together by said cams, a driving element adapted to be continuously rotated, a pair of mechanisms each adapted to convert rotary motion into reciprocatory motion and connected on the one hand in driven relationship to said driving element with a phase displacement with respect to one another and on the other hand to one of said cams to oscillate the same through predetermined phase displaced angles determined by the phase displacement of said mechanisms said followers being so positioned in the paths of oscillatory movement of the respective cams that the periods of actuation of the followers by the cams overlap during movement of the cams in one direction of their respective oscillations and follow in succession without overlap during movement of the cams in the other respective directions due to the phase displacement between the cams, a movable carrier operable to displace at least one of said followers along the path of its cam to vary the extent of the effective overlap of the cams, a lever mechanism operable by an operator to actuate said carrier, a. device operable to vary the effective leverage of said mechanism anda governor responsive to the speed of said crank shaft and operatively connected to the leverage varying device to reduce the said lever-age during a predetermined lower speed range of the crank shaft.

15. In a valve actuating mechanism, the provision of a driving member adapted to be continuously rotated, a pair of mechanisms operable to convert rotary motion into oscillatory motion and operatively connected to said driving member with a phase displacement with respect to one another, a pair of oscillatory cams each operatively connected to one of said pair of mechanisms to be operated thereby through phase displaced angles determined by the phase displacement of said mechanisms, a Valve actuating member provided with a pair of surfaces one associated with each cam and each of which is disposed parallel to the path followed by the peak of its associated cam, a follower disposed between each cam and associated surface to transmit the thrust of the cam to the valve actuating member, said actuating member being adapted to be effectively actuate-d solely when both cams overlap in their action upon said followers, said followers being so located on the paths of movement of the respective cams that the actuation of the followers by said cams at least partly overlap during movement of the cams in one direction of the respective oscillations and follow separately in succession during movement of the cams in the other respective directions, and means operable to adjust at least one of said followers in its position about the axis of oscillation of the cam associated therewith.

16. In a valve actuating mechanism, the provision of a driving member adapted to be continuously rotated, a pair of mechanisms operable to convert rotary' motion into oscillatory motion and operatively connected to said driving member with a phase displacement with respect to one another, a pair of oscillatory cams each operatively connected to one of said pair of mechanisms to be operated thereby through phase displaced angles determined by the phase displacement of said mechanisms, a valve actuating member provided with a pair of surfaces one associated with each cam and each of which is disposed parallel to the path followed by the peak of its associated cam, a follower disposed between each cam and associated surface to transmit the thrust of the cam to the valve actuating member, said actuating member being adapted to be effectively actuated solely when both cams overlap in their action upon said followers, said followers being so located on the paths of movement of the respective cams that the actuation of the followers by said cams at least partly overlap during movement of the cams in one direction of the respective oscillations and follow separately in succession during movement of the cams in the other respective directions and means operable to adjust both said followers in their positions simultaneously about the axes of oscillation of their respective cams in directions such as to maintain the efiective overlap of the cams unaltered.

17. In a valve actuating mechanism, the provision of a driving member adapted to be continuously rotated, a pair of mechanisms operable to convert rotary motion into oscillatory motion and operatively connected to said driving member with a phase displacement with respect to one another, a pair of oscillatory cams each operatively connected to one of said pair of mechanisms to be operated thereby through phase displaced angles determined by the phase displacement of said mechanisms, a valve actuating member provided with a pair of surfaces one assooiated with each cam and each of which is disposed parallel tothe path followed by the peak of its associated cam, a follower disposed between each cam and associated surface to transmit the thrust of the cam to the valve actuating member, said actuating member being adapted to be effectively actuated solely when both cams overlap in their action upon said followers, said followers being so located on the paths of movement of the respective cams that the actuation of the followers by said cams at least partly overlap during movement of the cams in one direction of the respective oscillations and follow separately in succession during movement of the cams in the other respective directions, means operable to adjust at least one of said followers in its position about the axis of oscillation of the cam associated therewith independently of the other follower and means operable to adjust both said followers in their positions simultaneously about the axes of oscillation of their respective cams in directions such as to maintain the effective overlap of the cams unaltered.

STANLEY HERBERT ATIWOOD.

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