Патент USA US2121409код для вставки
June 21, 1938. H. R. RICARDO 2,121,409 TWO-STROKE INTERNAL COMBUSTION ENGINE Filed Oct. 15. 1935 2 Sheets-Sheet 1 Fig. 1. D2 D1 “4103 INVENTOR June 21, 1938.‘ H. R. RICARDO 2,121,409 TWO-STROKE INTERNAL COMBUSTION ENGINE Filed Oct. 15, 1935 2 Sheets-Sheet 2 m a c'/ \C’ -—c' D Fig. 3. D H1 H‘ c ‘\H 1 H C, . c , E I ’ C IIVVFAITOR 59/ ‘ . , . mms. Patented June. 21, 1938 2,121,409 ‘ UNlT-EDMSTATES PATENT OFFICE 2,121,409 'rwo-s'raoxr. INTERNAL-COMBUSTION ' ENGINE a Harry Ralph Ricardo, London, England Application October 15, 1935, Serial No. 45.158 In Great Britain October 19, 1934 ‘6 Claims. (Cl. 123-65) This invention relates to two-stroke internal combustion engines of the kind wherein a single sleeve valve which may have a combined oscil lating and reciprocating motion controls the dis charge of exhaust gases through one or more exhaust ports or ‘openings in the cylinder wall adjacent to the cylinder head while the admis- ‘ sion of scavenging air takes place through one or more ports or openings in the wall of the sleeve 10 valve towards the‘ end 01' the working chamber remote from the head. , For the sake of convenience the end oi! the cylinder, ‘sleeve and other parts adjacent to the cylinder head will be referred to as the upper end. 15 In a two-stroke internal combustion engine or ‘ the kind referred to-according to the present in-‘ vention the exhaust ports .in the cylinder wall adjacent to the head‘ are controlled by the edge of the end 01' the sleeve valve‘ so that no ports are formed in this end portion of the sleeve. No gas-tight vpart carried ‘by the cylinder head ex tends into and engages the adjacent end of the the exhaust ports during the high pressure part of the cycle than the remaining part of the sleeve, the thinned part may either be of substantially constant thickness or tapered, while the remain ing part of the sleeve may either be of uniform 5 thickness throughout its length or may be thick ened over that part in which the inlet or, scaveng ihg ports are formed. This latter arrangement is convenient, for example, where the thickening constitutes a strengthening band at the part to 10 which the mechanism for imparting movement to the sleeve is attached. ‘In any case, the scav enging ports may be so formed that the charge entering through them has imparted to it a sub stantial component in a tangential direction with- 15 in the cylinder. ‘ The obliquity of the inlet ports for this purpose is determined in accordance with the degree of “swirl” which it is ‘desired to impart to the incoming charge as may be requisite ac cording to whether the invention is applied to an 20 engine‘of the compression ignition type in which , bore of the sleeve and the sleeve reciprocates only this swirl is utilized to assist the distribution of , between the piston and the cylinder wall. The ‘fuel throughout the air or to ‘an engine operating 25 end part or the sleeve which controls or deter with spark ignition in which less swirl is usually mines the uncovering of the exhaust ports is preferable or, again, to engines of the compresconveniently made thinner than the remaining sion ignition type wherein little or no swirl about the cylinder axis is required, any organized tur or main portion of the sleeve or is otherwise. weak bulence or the air charge which may be required 30 ened so that this part of the sleeve can expand being e?'ected in some other way, for example by under the internal gas pressures during operation forcing the ‘air'charge ‘during the compression of the engine to assist in maintaining a substan tially ?uid-tight joint between this part of the stroke from the cylinder bore into a combustion sleeve which lies above the exhaust ports during chamber through one or more restricted passages. the compression and ?ring periods‘ and the cylin ' The arrangement is preferably such that at maxi~ 35 der wall. ‘Further, the arrangement is conven mum opening of the exhaust ports the upper edge iently, such that the part of the sleeve which - of the sleeve does not lie above and is preferably covers the exhaust ports during the later part of substantially coincident with the lower edge of ‘ the compression stroke and the earlier part of the exhaust ports. ‘ 25 30 35 ' the ?ring stroke of the piston is then shielded by The invention may be carried into practice in various ways, but one construction according to rangement preferably being such that at the end‘ of the piston stroke the uppermost piston ring lies with its upper edge in or beyond the plane of the upper edge of the exhaust ports; In this way, this invention as applied to an engine operating 40 40 the piston from internal gas pressure, the ar while expansion of the wall of the upper end por-‘ tion of the sleeve under internal gas pressure can take place to assist in maintaining a substantially gas-tight joint‘ between this part of the sleeve and the cylinder wall, the risk of distortion of the 50 wall of the sleeve due to the internal gas pres ‘ sure tending to cause this wall to be forced into the exhaust ports around it is reduced or elimi , nated. Where, as described above, the sleeve is made thinner over that end portion which lies above on the liquid fuel injection compression ignition system and two modi?cations thereof are illus trated somewhat diagrammatically by way of ex ample in the accompanying drawings, in which Figure 1 is a sectional elevation, . 45 ‘Figure 2 is a section in the plane 2—-2 of Fig ure 1, . ‘ Figure 3 ‘is _ a sectional elevation of part ‘of the upper end ‘of the cylinder and of the cylinder head showing one modi?cation, and 5 Figure 4 is a sectional elevation showing a mod cation which may be made to the upper end of the sleeve valve. ‘ i In the construction illustrated in Figures 1 and 2 the engine, comprises a crank case A having 55 9,121,400 2 mounted therein a crankshaft B and connected to a water-cooled cylinder C which may be formed of an aluminium alloy. To the upper end of the cylinder C is secured a cylinder head D contain-l ing a water-cooled combustion chamber Dl of smaller diameter than the‘ cylinder bore provided ' with a fuel sprayer D‘, the axis of which lies substantially parallel to the axis-of the cylinder and combustion chamber and is displaced from 10 the combustion chamber axis. Formed in the wail of the cylinder C adjacent to its upper end are a series of exhaust ports C1, communicating with exhaust galleries C' provided with outlets at C8 adapted to be attached to an exhaust pipe. less'than the bore of the cylinder below the ex haust ports. The provision of this taper, while being in some cases desirable’ where an aluminum alloy or like high expansion‘ cylinder is em ployed, would in general be unnecessary where a cast iron cylinder were used. The thickness of the main part of the wall of the sleeve- valve E and of the upper part of reduced diameter may vary, but. in an engine of 15 Also formed in the cylinder at a point adjacent to the upper end of the crank case is a circum ierentially arranged inlet or scavenging gallery 0‘ to which scavenging air under pressure is sup plied, for example in known manner from a blower. Mounted within the cylinder is a sleeve valve E formed, for example, of steel in the wall of which is formed a series of inlet or scavenging the compression ignition type such as that shown, having a sleeve the internal diameter of which is of the order of ?ve and a half inches, the thickness of the part of the sleeve which at the end of its upstroke lies above the exhaust ports, or at least the upper edge portion of such part, 16 is preferably of the order of one per cent or less of the sleeve diameter where the sleeve is formed of steel, this thickness being such that this upper end part of the sleeve will expand under the internal pressure towards the end of the 20 ports 1:‘ communicating with‘the inlet gallery and arranged tangentially with respect to a circle having for centre the axis of the cylinder so that the scavenging air passing therethrough from the inlet gallery C‘ will tend to _ rotate about the cylinder axis. 80 ~ _ The sleeve E is provided at its lower end with a thickened part E3 rigidly connected to or formed integral with which is a pin E‘ freely engaging a bore in a member F the outer surface of which is part-spherical and is freely mounted in a corre spondingly internally part-spherical member F1 mounted on the upper end of a coupling rod F2 an intermediate point in which is pivoted to one end of a link I", the other end of which is piv oted to the crank case A, while the lower end of 44Tthe rod 1“01 is provided with a strap F‘ engaging an eccentric F‘ secured tow the crankshaft B. This mechanism will impart a combined oscillating and reciprocating motion to the sleeve in known manner. ‘ ' A piston G reciprocates within the sleeve valve E and is connected by a connecting rod G1 to a crank B1 on the crankshaft B in known manner. The crank B1 and the eccentric F‘ are ap proximately in phase so that while a combined 50 oscillating and reciprocating motion will be im- ‘ parted to the sleeve E in known manner, the end of the upward movement of the sleeve will nearly coincide with the end of the upward or compres sion stroke of the piston, while the end of the 55 downward movement of the sleeve will coincide with the end of the downward or firing stroke of the piston, the upper edge of the sleeve at the end of its downward movement preferably sub stantially coinciding with the lower edge of the exhaustports. . The bore of the upper end portion of the sleeve E, which at the end of the upward movement of the sleeve lies above the exhaust ports, is tapered or reduced in thickness as shown at 65 E5, while the upper end of the cylinder bore may be tapered to a small degree which cannot be readily illustrated, the smaller diameter of the taper in the cylinder bore being adjacentto the upper end of the cylinder, and the taper extend 70 ing downwards to a point adjacent to the upper edge of the exhaust ports 01. This taper is such that the bore of the uppervend of the cylinder has a diameter which, in a cylinder having a bore of the order of ?ve and a half inches diameter, is of the order of two thousandths of an inch compression stroke and during the firing period to assist in maintaining a ?uid-tight joint be tween it and the cylinder wall. A circumferential oil groove 0‘ is formed in the cylinder wall at a point between the scavenging 25 gallery C4. and the exhaust ports C1, oil being fed under pressure to this groove through a The operation of the engine is as follows: As the piston G moves downwards from its 30 upper dead centre on the firing stroke, the sleeve E also moves downwards but more slowly, and the upper edge of the sleeve begins to uncover the exhaust ports C1, just before the piston G begins to uncover the scavenging ports E2 in the 35 sleeve ‘valve.’ The exhaust period thus begins shortly ‘before the admission of scavenging air through the scavenging ports, so that the waste gases are driven out and the working chamber is charged with air in readiness for the next com 40 pression stroke, this air being in a state of rota tion about the cylinder axis due to the tangential arrangement of the scavenging ports E’. During the later part of the compression stroke of the piston and the early part of the ?ring stroke it 45 will be seen that the part of the wall of the sleeve E then covering the exhaust ports C1 is shielded by the piston G from internal gas pressure. Thus, though the pressure within the working chamber can then act upon the wall of the sleeve valve 50 lying above the exhaust ports, thereby expanding this part of the sleeve to assist in maintaining gas-tight engagement thereof with the adjacent part of the cylinder wall, the internal pressure, when at or near its maximum value, cannot act 55 on that part of the sleeve lying immediately over the exhaust ports C1. The tendency for the wall of the sleeve valve E to be expanded into the ex haust ports C1 by the internal gas pressure is thereby reduced. ‘ 60 It will be seen that the exhaust ports are controlled not by ports in the sleeve valve but by the adjacent edge of the sleeve valve and that the tendency for the thin portion of the sleeve to expand under the internal gas pressure during 65 the compression and firing strokes tends to main tain a gas-tight ?t between the upper end por tion of the sleeve and the cylinder, this gas-tight fit between the upper end of the sleeve valve and the adjacent part of the cylinder being greatest 70 when the pressure is highest. The necessity for providing a plug-like cylinder head which projects into the cylinder, as has hitherto been common practice, with head rings between the sleeve and the plug-like head, is thus obviated and the cool 75 9,121,409 ing of the combustion chamber is also facilitated since this chamber does not have to be formed ' within the plug-like cylinder head and can there fore be directly accessible. Furthermore, the ab sence of head rings as are used on plug-like cyl inder heads ensures that 'di?lculties due to car boning-up of the head rings, which di?iculty is more liable to occur in engines of. the two-stroke 10 than in these of the four-stroke type, cannot arise. It will be appreciated that since there are no ports in the part of the sleeve valve E adjacent to the exhaust ports, this part can be made suf ?ciently thin to permit the desired expansion under the‘action of internal gas pressure, while 15 any possibility of warping occurring due to the bars or bridges which would be necessary between adjacent ports if such were provided in the thin part of the sleeve valve. due to heat flow, is avoided. 20 , The lubrication of the lower part of the sleeve may be effected in some known manner by splash from the crank case, while the upper part of the sleeve is lubricated'by oil from the oil groove C5, 1 this 011 being carried to the extreme upper part 25 of the sleeve across the bars 0'' which divide the exhaust ports (22 in the cylinder, the combined oscillating and reciprocating movement of the sleeve tending generally to distribute oil and maintain adequate lubrication over the whole of 30 the outer surface of the sleeve. 3 part-E6 may be of a high-expansion material such as an austenitic steel or cast-iron. It is to be understood that the construction more particularly described above is given by way-of example and that details may be modi?ed without departing from this invention. For ex ample, the invention may be applied to an engine in which the cylinder and cylinder head are air cooled and to engines of the vaporized charge spark ignition type, while the mechanism for op 10 erating the sleeve and other details‘ of construc tion may be modi?ed considerably. Further, the invention may be applied to double-acting two-stroke engines, in which case the sleeve would be operated from a point inter 15 mediate in its length and each end thereof would be formed and arranged to cooperate with ex haust ports in the manner according to this in— vention, scavenging ports, of which a single set may be common to both working chambers, being 20 provided at a point intermediate in the length of the sleeve. It is also to be understood that, although in the present speci?cation and the followi/ng claims exhaust ports are referred to, this expression is to 25 be interpreted as including a single continuous exhaust slot undivided by bars engaging the outer surface of the sleeve. I claim:~ 1. An internal-combustion engine, comprising 30 The bars 07 are conveniently of somewhat streamline form on their sides remote from the a cylinder with a cylinder head and provided cylinder bore for ~the purpose of reducing the’ in its wall with exhaust ports adjacent to said head, the part of the cylinder bore on the side tendency for carbon to form thereon. of the exhaust ports nearest to the cylinder head 35 Figure 3 shows a modi?ed arrangement which being provided with a slight taper, the smallest 35 in some cases may be desirable, and may be ap plied to an engine otherwise similar to that shown diameter of which is adjacent to the cylinder in Figures 1 and 2, wherein the upper end portion head; a piston operable in said cylinder; and a sleeve valve movable between the piston and the of the cylinder barrel is constituted by ‘a sepa 10 rate member or liner H having a ?ange H1 cylinder and controlling the exhaust ports with the edge at one end of the sleeve. lying between the upper end of the cylinder prop 40 2. A two-stroke internal combustion engine ac er and the cylinder head D. This liner may be cording to claim 1, in which the taper of the particularly convenient where an aluminium cyl inder is employed, ‘the sleeve being of normal cylinder bore is such that the end of the cylinder ‘ steel, and not only provides the working surface bore adjacent to the cylinder head has a diameter for the upper end portion of the sleeve which which is of the order of l/émo of the diameter of 45 the cylinder bore less than the diameter of the serves to seal the exhaust ports, but also pro vides a member which can readily be replaced part of this bore at that side of the exhaust ports in the case of wear taking place. In such a case which is remote from the cylinder head. 3. A two-stroke internal combustion engine the liner H is preferably of cast-iron or other comprising a cylinder with a cylinder head and material having about the same expansion co provided in its wall with exhaust ports adja 50 e?icient as the sleeve. . cent to the said head, a piston operable in said Fig. 4 shows a modi?cation of the upper end of'the sleeve which may also be applied to an cylinder and a sleeve valve movable between the engine similar in other respects to that shown piston and the cylinder wall and controlling the exhaust ports of the cylinder wall by its edge, 55 in Figures 1 and 2, wherein the upper end por tion of the sleeve is formed separately from the the end portion of the sleeve which at the end main part of the sleeve and is constituted by an of its stroke towards the cylinder head lies be annular part E6 connected to the main part E of yond the exhaust ports being weakened as com 60 the sleeve by a circlip E7 engaging a shoulder on pared with the remaining portion ‘of the sleeve, the part E5 and a groove in the part E as shown, the thickness of said part of the sleeve being at 60 its edge of the order of not more than one per the engaging surfaces of the parts E and E6 be-i cent of the diameter of the cylinder bore. ing somewhat cut away, as shown at E8, to en 4. A two-stroke internal combustion engine, sure that there shall be a gas seal between the comprising a cylinder with a cylinder head and 65 inner edges of these parts and that ‘pressure provided in its wall with exhaust ports adjacent 65 within the cylinder will thus tend always to main ‘ tain the part E6 in close contact with the part E. to said head and a scavenging air belt remote The parts E and E6 in this construction may be from the exhaust ports, the. part of the cylinder formed of different metals or may be formed of ~ boreon the side of the exhaust ports nearest to the cylinder head being provided with a slight the same metal, the arrangement in either case taper, the smallest diameter of which is adja 70 permitting the part E6 to be renewed in the case cent to the cylinder head; a piston operable in of wear thereof taking place. In particular, said cylinder; and a sleeve valve movable be where the cylinder is of aluminium alloy or other tween the piston and the cylinder and control high-expansion material, and the sleeve of car ling the exhaust ports. 75 hon-steel or other low-expansion‘ material, the '5. A two-stroke internal combustion engine, 75 4 8,121,409 > ' comprising a cylinder with a cylinder head and sleeve to such extent that it can expand'under to said head and scavenging air belt remote from ?uid-tight Joint between it and the cylinder wall. 6. A two-stroke internal combustion engine ac cording to claim-4. in which the taper oi the cylinder bore is such that the end 0! the cyl gas pressure during operation of the en— provided in its wall with exhaustports adjacent internal glue ‘and thus tend to maintain a substantially the exhaust ports, the part oi the cylinder bore on the side of the exhaust portsnearest to the cylinder head being provided with a-slight taper, the smallest diameter of which ‘is adjacent to the cylinder head; a piston operable in said cyl inder; and a sleeve valve movable between the inder bore adjacent to the cylinder head has a diameter which is of the order of $500 0! the at the end of its stroke towards the cylinder head lies beyond the exhaust ports being weakened as compared with .the remaining portion or the the exhaust ports which is remote from the cyl inder head. diameter of the cylinder bore less than the'di 10 10 piston and the cylinder and controlling the ex meter of the part of this here at that side or the end portion oi’ the sleeve which haust ports, > HARRY RALPH RICARDO.