US2337245A - Internal combustion engine - Google Patents

Description

Dec. 21, 1943.

H. M. JACKLIN INTERNAL coMBUsTIoN ENGINE Filed Aug. 22, 1941 2 sheets-sheet 1 l/lllllll/ Dec. 21, 1943. H. M. JACKLIN INTERNAL COMBUSYTION ENGINE Filed Aug. 22, 1941 2 Sheets-Sheet 2 nlllllilllllmdl u ihnen/Enf.

Patented Dec. 21, 1.943

UNITED STATES PATENT OFF/ICE 2,331,245 INTERNAL coMBUs'rIoN ENGINE i Harold M. Jacklin, La Fayette, Ind. Application August 22, 1941, serial No. 408,006

(cries-65) 6 Claims.

This invention relates to two-stroke cycle engines of the uniow type. In such engines, ports located at opposite ends of the cylinder are uncovered at or near the end of the working stroke of the piston, the burnt gases are exhausted through the ports at one end of the cylinder,

l while air or a mixture of fuel and air is admitted through the ports at the opposite end of the cylinder. y I

Heretofore, engines of this genera-l kind have been of either of two types. Inv the rst type, called the opposed piston type, two reciprocating pistons move oppositely in a single cylinder and respectively uncover the inlet 'and exhaust ports as they near the ends of the Working strokes. In the other type, there is a .single working piston which uncovers cylinder ports at one end of the cylinder as it nears the end of its Workingstroke, while the ports at the opposite end of the cylinder are controlled by a poppet valve. The opposed piston-type of engine has certain disadvantages because of the problernsencountered in interconnecting the two working pistons. The poppet valve type of engine is open to the objection that relatively large forces must be used in order to obtain the necessary quick opening andv quick closing of the valves, and such largeforces entail high unit bearing-pressures and necessitate the use of heavy springs.

It is the object of my invention to produce a two-stroke cycle engine of the uniow type which will be free from the above noted disadvantages possessed by prior engines of this kind. More specically, it is my object to provide an enginey which may have a single Working piston controlling or aiding in the control of one set of ports and in which the other set of portsr will be controlled by valve-operating mechanism which will provide a quick opening and quick closingl of the ports and do so without the imposition of relaf tively large forces.

In carrying out my invention, I employ a cylinder having inlet ports at one end and outlet po'rts at the other. One set of these ports is controlled by a reciprocable valving element which may be either a piston or a sleeve, while the other set of ports may be controlled at leastin part by the working piston. The yalving element is reciprocated in the cylinder by an eccentric operating at the same speed as the crankshaft of the engine; but instead of connecting the `valving element directly to such eccentric, which would cause the valving `element to operate withl an approximately harmonic motion, I interpose be'- tween the valving element arid the eccentric various forms, as will be more fully broughtout 1 hereinafter.

The accompanying drawings illustrate my invention: cylinder of an engine embodying a piston valve which is under the joint control of two'eccentrics; Fig. 2 is a diagram showing movements of the working piston and piston valve during the twostroke "cycle of the engine; Fig. 3 is a fragmental -view similar to Fig. 1 illustrating the upper end vof a piston-valve engine with a movement-modifying means' embodying a single eccentric, the valve being shown as open; Fig. 4 is a view similar to Fig. 3 showing the valve closed; Fig. 5 is a sectional view similar to Fig. 1, but showing -a valving element in the form of a sleeve operated by two eccentrics; Fig. 6 is a diagram illustrating movements of the piston and sleeve in the construction of Fig. 5; Fig. 'l is a Iragmental view similar to Fig. 5 showing a modified form of double-eccentric sleeve-operating mechanism; and Fig. 8 is a view similar to Fig. 'l illustrating a sleeve-operating mechanism embodying a single eccentric.

The engine illustrated in Fig. 1 has a working cylinder Il! -provlded at one end with an annular series of ports II and at the I a second annular series of ports I2.l Either set of these ports may serve as inlet ports and the other as exhaust ports; butit is `preferable in most instances that the upper ports be used as For the purpose `of controlling the exhaust ports I2,` a piston valve 20 provided at its lower ,i end with a junk ring 2'I is mounted for reciprocation in the cylinder II'I in such a manner that the lower edge of the junk ring will pass Vacross the ports I2 and open and close them as the valve 20 reciprocates. Between the valve 20 and piston I5, the cylinder is provided with an opening 25 for the receptlonfof a spark plug. or other ignition device, if the engine isof a type requiring igni- Fig. 1 is an axial section through a opposite end with i being such l tion, or for the reception of a fuel-injection nozzle, if the engine is of the compression-ignition type.

For the purpose of controlling movements of the valve 20, there is mounted above the head end of the cylinder a rotatable main eccentric 30 adapted to be driven at crankshaft speed as by means of a train of gears y3l. Also mounted above the head end of the cylinder is a second or auxiliary eccentric 32 arranged to be driven at twice crank-shaft speed. Connecting rods 33 and 34 serve to connect the eccentrics 30 and 32 respectively with pins 33' and 34Vv in the opposite ends of a lever 35 pivotally connected at an intermediate point to the valve 20, as through a pivot pin 36. y f

The exact movement imparted to the valve by the two eccentrics and 32 will depend upon a number oi factors among which are the respectivethrows of the two eccentrics, their phase-relationship, and the relation between the distances of the pins 33' .and 34' from the pin 36'. Ordinarily, the eccentric 30, which rotates at the same speed as does the crank shaft, will lead the crank I'I by an angle between 8 and 15, while the eccentric 32 will lead the crank I'I by an angle between 16" and 30, sothat the valve 20 will reach its lower dead-center 8 to 15 before the working piston I5 reaches its outer (upper) dead-center position. The relative spacing of the pins 33 and 34 from thepin 36 may vary considerably, but I prefer to make the distance from the pin 33'- to the pin 36 between 15% and v50% of the distance between the pins 33' an'd34'.

The diagram shown in Fig. 2 represents the disposition of the Valving events within a complete cycle. In this diagram, the line 40 represents the upper edge and the line 4I the lower edge of the p'orts I2. while the line 42 represents the upper edge and the line 43 the lower edge of the ports I I. 'Ihe curved line 44 represents the displacement of the lower edge of the junk ring 2I during a complete cycle (360 of crankshaft rotation) beginning with Athe working piston I5 at headenddead center; while the curved line 45 represents displacement of the upper end of the working piston I5 during the same interval. Whenever the curved line 44 lies above the horizontal line 4I, the ports I2 will be open, as represented by the shaded area E6; and whenever the line 45 is located below the line 42. the ports II will be open,.as indicated by the shaded area 417. The dotted line 48 shown at the top of Fig. 2 represents approximately what displacement of the lower edge of the junk ring 2I would be if the valve 20 were directly connected to a single eccentric operating at crank-shaft speed.

From a comparison of the full-line 44 and-th dotted-line 48, it will be apparent that during the time in which the lower edgeof the junk ring 2I is moving across the port I2 its speed is relatively rapid. In order to obtain a port-opening of the same duration with the valve 20 directly connected to a single eccentric it would be necessary to reduce greatly the height, and therefore the are of the exhaust ports I2. It will be further app rent from Fig. 2 that when the main piston I5 is near the upper limit of itsv movement in the vcylinder the speed of the valve 20 is relatively slow. It is when the working piston is near the upper .end of its stroke that working pressures within the cylinder are at their highest; and it is advantageous i'or the piston valve 20 and its associated Junk ring 2| to undergo as little move-v for the exhaust ports to close while the inlet ports v are still open. It is for this reason that a lead is imparted to the eccentrics 30 and 32; and because of the existence of this lead the shaded area 06 in Fig. 2 is displaced to the left from the center of the diagram. From the diagram which constitutes Fig. 2, it will be apparent that the opening of the exhaust ports I2 would occur about 10 to 15 (of crankshaft rotation) earlier than does' opening of the inlet ports I I, while closing of the exhaust ports I2 would occur from 15 to 20 earlier than closing of the inlet ports.

The engine illustrated in Figs. 3 and 4 embodies the same ported cylinder I 0, piston I5, and pistonvalve 20 as does the engine shown in Fig. 1. In this instance, however, the piston-valve 20 is connected through a link 50 to one arm of a bellcrank lever 5I whose other arm is connected by a-connecting rod 52 to an eccentric 53 rotating at crank-shaft speed. As the eccentric 53 rotates, the bell crank 5I .oscillates about its axis and causes reciprocation of the valve 20 in the cylinder to open and close the exhaust ports I2.

The parts of the mechanism operating the piston-valve 20 of Figs. 3 and 4 are so arranged that when that valve is at lower dead center, or in the position illustrated in Fig. 4, the points of interconnection of the link 50 with the valve 20 and bell crank 5I will be in approximate alinement with the axis of the bell crank. This arrangement results in imparting to the valve 20 a movement having the same characteristics as is imparted to the valve by the mechanism illustrated in Fig. l-namely, the valve moves relatively rapidly Y While its lower yedge is crossing the exhaust ports I2 and relatively slowly afterithas covered the ports I2. Moreover, in the arrangement shown in Figs. 3 and 4, when the valve 20 is at lower dead center, the heavy cylinder-pressures existing at that time are transmitted substantially directly through the link50 and bell crank 5I to the bell-crank pivot and are not reected to any great extent as forces imposed on the connecting rod 52 and eccentric 53.

The engine illustrated in Fig. 5 is of the sleevevalve type. The cylinder I0 is provided at its opposite ends with two sets of'ports 60 and 6l the former of which, located at the lower end of the cylinder, are assumed as before to be intake ports, while the latter are exhaust ports. The upper end of the cylinder I0 is closed by a head 62 having a downwardlyextending, centrally located, cylindrical boss 62' somewhat smaller than the bore of the cylinder I0 in order to provide an annular space for the reception of the upper end of a sleeve valve 63 within which the working piston I5 reciprocates. The head 62 is provided withone or more sealing rings preferably including at its lower end a relatively wide junk ring 64. The sleeve 63 extends downwardly through `the cylinder I0 and is provided in the region of the cylinder ports 60 with a circumferential series of intake ports 65 and in the region of the cylinder ports 6I with a. circumferential series of exhaust ports 66. 'I'he opening 25, for

the reception of an 'ignition or fuel-injection device, is in this engine disposed in the head 62.

For the purpose of reciprocating the sleeve 63 to control the opening -and closing of the intake and lexhau/st ports I employ, as in the engine shown in/Fig. 1, amain eccentric 10 `operating at crank-shaft speed and an auxiliary eccentric 1l cperatingattwice crank-shaft speed. The

main eccentric may be carriedby the crank shaft of the engine, yand'is so illustrated; while Veilect of movement of the sleeve andpiston upon the opening and closing of the inlet and exhaust ports. In this diagram, the line 11 indicates the elevation of the lower edge'of the Junk ring 65, and the curved line 18/repre'sents vertical displacements of the piston I5. 'I'he twov equidistant curved lines 19 and 30 represent respectively the displacements of the upper and lower edges of the exhaust ports 66 in the sleeve; while the two equidi'stant lines 8l and 32 represent displacements of the upper and lower edges of the inlet ports 65 in the sleeve. As will be. readily apparent, wheneverthe vline 80 lies below the line 11 the exhaust ports '63 will be open, and when# ever the line 18 lies below the line 3| `the inlet ports will beopen.

It :will be noted in'Fig. 6 that the valveoperating mechanism imparts to the sleeve 63 a move.,

ment similar in character to that imparted to the piston-valve 20 by the double-eccentric valve- Flg. 'I I have shown a construction in which 'a lever 33. has oneend connectedl to the sleeve 63 and its other Aend pivotally connected to the connecting rod `13, while the connecting rod 12 is pivotally connected to an intermediate point ofthe lever.

In the arrangement illustrated in Fig. 8. the sleeve 63 is operated by a single eccentric 81 rotating at crank-shaft speed and convenientlymounted directly on the crankshaft. Here, the

lower end of the sleeve is connected through aV link 88`with one end of a lever 89, whose opposite end `is connected through a connecting rod 93 with the eccentric 81. The arrangement of the parts is such thatl as the sleeve approaches the upper end of its'mcvement. where the ports are al1 closed, the pcintsgyf pivotal connection of the link 88 with the sleeve 63 and lever 89 approach alinement with the axis*about which the lever swings. The position of the parts when. the sleeve is at the upper limit of its movement is indicated in dotted lines in Fig. 8. 'I'his Yarrangement impartsto thesleeve 63 a comparativelyrapid movement while the ports are being openedV and closed and a comparatively slow movement"` after the ports have been closed, and also reduces the forces to which the eccentric 81 and connecting rod 90 are subjected when the piston I5 is near thehead end of the cylinder and cylinder pressures are high.

4 In all the modifications illustrated in ithe drawing, the movement of the valving elem nt,

'whetherit b e a piston or a sleeve, has essenti lly the-same general character. That is, the move- .mentor the valvingI element is morerapid than operating mechanism shown in Fig. 1.' That is, 1

during the time lthe working. piston i3 is near the upper limit of its4 stroke with all'portsclosed movement of the sleeve 63 is relatively slow;

In' the case of the inlet ports '35 which are opened and closed by relative movement iof the sleeve and piston, the relative rapidity of sleeve movement tends to retard the speed o! port-opening and port-closing; for during' each of these events thesleeve and piston are moving -in the same direction with the latter moving the more rapidly. However, the speed of the piston-is so much greater than the speed of theA sleeve, that fthe. increase of ,sleeve-speed which resultsyi'ro'm the incorporation of my inventiondoes not obwhereas when the sleeve is moving te open or Qsubjectedto high pressures' close the ports its movement is relatively vrapid.

a'harmonic motion would be during valve-opening and' valve-closing, but 'is materially slower than a harmonic motion after the ports have once been closed., 4Since the highest cylinder pressures-exist when. the ports are closed, the valving .element will move only slightly while which feature resuits-in a -material reduction in, wear. This element results fromV modifying the action of an eccentric operating at crank-shaft speed.

In all embodiments shown, the action of the i eccentric is modied through the employment of a lever which forms part of the mechanism by whichthe valving element is connected to the eccentric operating at crank-shaft speed. l In. `the arrangement illustrated in. Fig. l? the element 35 maybe regarded as a lever of the second cl'ass fulcrumed ,at 34', receiving the'joperat-v lat'its point of connection .with'lthe connecting The eccentrics 10 and 1|,.like the eccentrics 33 and 32 in the' engine shown in Fig. 1, can be given'leads over. the crank shafty so as to throw the period in which the exhaust ports ,63 are open ahead of the midpoint of the cycle.

It is not essential in either of the valve-oper?,

ating mechanisms illustrated in Figs 1 and 5 .that the valve be connected to an intermediate,

point on the lever (35 or 1I) actuated by the two eccentrics; as movement of the same general character can be imparted to the valve by f connecting it to one end of the lever. Thus. inl

ing effort, at3'3', and having the load applied to itat 3 3. The element 1l in Fig. 5 may also be regarded as alever ofthe second class fulcrui'ned rod 13, receiving. the operating effort through the connecting rod-12, and having theload apcharacteristic of the movement of the valving plied to it at its point oi' pivotal connection with v the sleeve 63. On the-same basis, the element 35 in Fig. 7 would be a lever of the third class, fulcrumed at its point of interconnection with the connecting rod 13, receiving the'cperating eifort at an intermediate point through the connecting rod 12, and4 having the load applied at :its outer end where it is connected to Athe sleeve. In-all three of these arrangements, the' points at which the operatingeilort and the load are respectively applied to the-lever moveback and forth in lines which are generally parallel to the cylinder axis:l

'and the lever-fulcrum is reciprocated 'also along a line generally par liel to the cylinder axisand spee at twice crank-shaftYV rapid valve movement during port-opening and d to produce relatively port-closing and relatively slow valve movement when all ports are closed. s

In the modification of my inventionshown in Figs. 3`and 4 the lever which modifies the action ofthe eccentric is the bell-crank I. In' this case the fulcrum of the lever-i. e., the axis of the bell-crank--is xed, and modification of the action oi"` the eccentric is obtained by so arranging the parts that the path of the point at which the operating effort is applied to the lever is in general ralinement with such operating effort throughout the entire range of swinging movement of the lever 5l, while the path of the point at which the load is applied to the lever is generally perpendicular to the path' of valve movement after the ports have been closed. In the respect just noted, the construction shown in Fig. 8, which also-employs a fixed fulcrum or pivot, is the same as that shown in Figs. 3 and 4. The f ct that the loaded end of the lever (5| or 89) is oving in a direction lgenerally perpendicular to the path of valve movement during most of the interval in which the ports are closed makes it possible for movement of the valve to be relatively slight in comparison with movement of the lever.

As previously noted, the exact shape of the r curve 44 (Fig. 2) representing axial displacement of the valve 2U willdepend upon several factors. Because the eccentric 32 rotates at twice the speed of the eccentric 3U, the right-hand end of the Alever 35 will reciprocate vertically twice -whilel the left-hand end of such lever is reciprocating once. If, as the result of the relation between the throws ofthe eccentrics and of the spacing of the pins 33', 34', and 36, the effect of the eccentric 32 upon movement of the valve 20 is great enough, the valve may change its direction of movement four times instead of twice during each cycle. That is, after moving upwardly for a distance from its lowermost position, the valve may reverse itself and move downwardly for an interval and then resume an vupward movement which continues until the valve has reached the upper limit of movement 2| is well vbelow the ports l2 so that the desired valve timing will not be interfered with.

` The same possibilityof an intermediate and temporary reversal of valve movement in each half of the cycle exists in the ca'se of the sleevevalve engines illustrated in Figs. 5 and '7 and can in similar manner be prevented from aiecting the valve-events.

I claim asmy invention:

l. In a' two-stroke cycle internal combustion engine, aworking cylinderhaving inletports at one end and exhaust ports at the other end,a working pistonreciprocable in said cylinder and and a pair of lever-operating devices.' said devices and said valve being connected to said lever at three points spaced along the lever, said devices operating to reciprocate the lever-points to which they are respectively connected, one point at a rate corresponding l to the rate at which the piston reciprocates and the other point at twice such rate, said lever and operating devices being proportioned to cause said valve to produce a complete opening of its associated ports in less than 60 of crank-,shaft rotation.

2. In a two-stroke cycle internal combustion engine, a working cylinder having inlet ports at arranged to uncover one set of such ports when at the adjacent end of the cylinder, a crankshaft operatively connected to saidpiston, a

' said piston, said means including a lever extending generally perpendicularly to the cylinder axis one end and exhaust ports at the other end, a-

working vpiston reciprocable in, said cylinder and arranged to uncover one set .ciV such ports when at the adjacent end ofthe cylinder, a valve axially reciprocable in said cylinder for controlling the other set of ports, and means for reciprocating said valve intimed relation with said piston, said means including a lever extending generally perpendicularly to the cylinder axis and a pair of lever-operating devices, said devices and said valve being connected to said lever at three points spaced along the lever, one of said devices operating to reciprocate the lever-point to which it is connected at a rate equal to that at which the piston reciprocates and the other of Said devices operating to reciprocate the lever-point to which itis connected at twice such rate, the distance between the points of connection of said lever to said valve and the former of such devices being less than the distance between the peints of connection ofy the lever to the valve and the latter of such devices.

3. In a two-stroke cycle internal combustion engine, a working cylinder having inlet ports at one endand exhaust ports at the other end, a working piston reciprocable in said cylinder and arranged to uncover one set of such ports when at the adjacent end of the cylinder, a valve axially reciprocable in said cylinder for controlling 'the other set of ports, and means for re` ciprocating said valve in timed relation with said piston, said means including a leverI extending generally perpendicularly to the cylinder axis and a pair of eccentrics one of which rotates at a speed corresponding to that of reciprocation of said piston and the other of-which operates at twice suchvspeed, said eccentrics and said valve being operatively connected to said lever` at threepoints spaced along the lever, the distance between the points at which said lever is connected to the valve andthe slower eccentric being less than the distance ybetween the points at which the lever is connected to the valve and the faster eccentric.

,4. In a two-stroke cycle internal combustion engine, a working cylinder having inlet ports at one end and exhaust ports at the other end, a working piston reciprocable in said cylinder and arranged to uncover one set of such ports when at the adjacent end of the cylinder, a valve axially reciprocable in said cylinder for controlling the other set of ports, and means for reciprocating said valve in timed relation with said piston. said means including a lever extending generally perpendicularly tothe cylinder axis and a pair of eccentrics o ne of which` rotates at a speed corresponding to that of reciprocation of said piston and the other of which operates at twice such speed, said eccentrics and said valve being operatively connected to said lever at three points spaced along the lever, said eccentric and lever being so proportioned to cause said valve to produce a complete opening' of its associated ports in less than 60 of crank-shaft controlling the other set of ports, and means for reciprocating said valve in timed relation with said piston, said means comprising a valve-operating eccentric rotating at a speed equal to that at which the piston reciprocates and mechanism including a lever operatively interposed between said eccentric and valve for eecting a relative reduction in the eilect of eccentricmovement upon'valve-movement when the ports controlled by said valve are closed and for increasing the eiect of eccentric-movement uponv valve-movement when such ports are being opened and closed by. said valve to an extent sumcient to produce complete'opening of such ports in less than 60 of crank-shaft rotation.

v engine, a working cylinder having inlet ports at one end and exhaust ports at the other end, a Working piston reciprocable in said cylinder and 6. In a two-stroke cycle internal combustion arranged to uncover one set of such ports when at the adjacent end of the cylinder, a crankshaft operatively connected to said piston, a i

valve. axially reciprocable in said cylinder for controlling the other set of ports, and means for reciprocating said valve in timed relation with said piston, said means comprising a valve-operating eccentric rotating at a speed equal to that at which the piston reciprocates and mechanism operatively interconnecting said eccentric and valve for effecting a relative reduction in the eiect of eccentric-movement upon valve-movement when the ports controlled by said valve are closed and for increasing the effect of eccentricmovement upon valve-movement when such ports are being opened and closed by said valve to t an extent suillcient to produce complete opening of such ports in less than 60 of crank-shaft rotation.

HAROLD M. JACKLIN.

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