AU7351898A - Arrangement in a combustion engine with internal combustion - Google Patents

Abstract

A combustion engine (10) having internal combustion, comprises a number of engine cylinders (21), which are arranged in an annular series around a common middle drive shaft (11). Each cylinder includes a pair of pistons (44, 45) movable towards and away from each other and a common, intermediate working chamber (K) for each pair of pistons. Each piston (44, 45) is equipped with its piston rod (48, 49) with associated support roller (53) which forms a support against its respective "sine" - curve shaped cam guide device (12a, 12b), which controls movements of the piston relative to the associated cylinder. A least the one (44) of the two pistons (44, 45) in each cylinder (21) is regulatably adjustable axially in the cylinder especially for regulating the compression ratio in the common working chamber (K).

Description

1 ARRANGEMENT IN A COMBUSTION ENGINE WITH INTERNAL COMBUSTION The present invention relates to an arrangement in a combustion engine having internal combustion, comprising a plurality of engine cylinders, which are arranged in an annular series around a common central drive shaft and 5 which have cylinder axes running parallel to the drive shaft, each cylinder including a pair of pistons movable towards and away from each other and for each pair of pistons a common, intermediate work chamber, while each piston is equipped with its axially movable piston rod, 10 the free outer end of which forms via a support roller a support against its curve-shaped, that is to say 'sine' curve shaped, cam guide device, which is arranged at each of opposite ends of the cylinder and which guides movements of the piston relative to the associated 15 cylinder. In US 4 432 310 and 5 215 045 there is shown an engine arrangement with a number of pistons which are arranged individually each in its separate cylinder. The cylinders are arranged in pairs in axially mutually 20 parallel rows and are equipped with pistons synchronously movable in pairs, that is to say the pistons are physically connected to each other in their respective pair of cylinders. There is employed in this connection a middle cam guide device, which is common to each and all 25 of the cylinders of the engine and which jointly controls each pair of mutually connected pistons. In other words WU 98/49436 PC/INU95/UU1ZO 2 each cylinder has its respective separate cylinder volume with its respective separate piston, but with a common control of each and all pistons in respective strokes. From for instance US 5 031 581 (1989) a solution is 5 known correspondingly as indicated by way of introduction. More specifically a four stroke combustion engine is known having two separate cam guide devices. Each cam guide device cooperates with its respective set of pistons and with its respective associated set of support rollers. The 10 cylinders are arranged in an annular series around the drive shaft. The pistons, which are received in pairs in a respective one of the cylinders, are served by two separate cam guide devices, that is to say the one piston of each pair of pistons is controlled by a first cam guide 15 device, while the remaining piston is controlled by a second cam guide device. Each cylinder is consequently equipped with pairs of separate pistons movable towards and away from each other each with its separate piston rod, which cooperates individually via an associated 20 support roller with a respective one of two opposite sets of "sine' - planes, which form a part of their respective cam guide device and which control the pistons according to a "sine" - concept known per se. The cam guide devices of the two axially distinct groups of pistons are arranged 25 axially endwise outside respective end of the engines. The piston heads of said pairs of pistons face mutually towards each other in a common working chamber of the associated cylinder, that is to say towards a common working chamber, which is arranged midway between said 30 pair of pistons. In GB 2 019 487 a four cylinder two stroke engine is shown with a pair of pistons going towards and away from each other in each of said four cylinders. An arrangement is employed where the ignition occurs simultaneously in 35 two of the four cylinders, that is to say in pairs of alternate cylinders. In the patent specification it is indicated that the contour of the cam can be designed so WU 9i5494ib 'IU/NU8iU]0 3 that the pistons can be moved in a most favourable manner in connection with expansion of the combustion product. There is employed a desired level or steady contour for emptying or scavenging of exhaust before new fuel is 5 introduced into the cylinder. In the drawings there is shown, in each of two mutually opposite cam grooves, a more or less rectilinear, local cam contour in mutual turning points lying directly opposite each other forming "sine" - curve portions. More specifically the rectilinear 10 cam contour is illustrated in only the one of two succeeding, turning points of the "sine"-curve forming "sine"-curve portions, namely where the respective pistons occupy one after the other their most remote outer positions with exhaust and scavenging ports open to the 15 maximum. The present invention, which primarily relates to two cycle engines, but which can also be applied to four stroke engines, takes its starting point as to arrangement in the piston and cylinder arrangement according to the 20 afore-mentioned US 5 031 581. With the present invention the aim is to be able to regulate the compression ratio in cylinders of the engine in a simple and ready, but at the same time controlled, precise and reliable manner, that is to say the aim is to 25 regulate the compression ratio in the common working chamber which is defined between two piston heads of the cylinder facing towards each other. The arrangement according to the invention is characterised in that at least the one of the two pistons 30 in each cylinder is regulatably adjustable in the cylinder for regulating the relative spacing between the pistons, especially for regulating the compression ratio in the common working chamber between the pistons. According to the invention one is consequently in a 35 position to regulate the compression ratio in the working chamber between two pistons of the cylinder by quite WO 98/49436 PCT/NO98/UU12O 4 simply regulating the position of only the one piston in its associated cylinder. With the present invention a particular aim furthermore is to be able to regulate the compression 5 ratio of the cylinders of the engine as a whole and to effect the regulation with one and the same control means. The arrangement according to the invention is in this connection characterised in that the position of the piston in the cylinder is adapted to be fixed via the 10 associated cam guide device of the piston by means of a separately regulatable arrangement. By the fact that the cam guide device is common to the one piston of each and all the cylinders there can be achieved effectively and in an accurately controllable 15 manner corresponding regulation of the position for said one piston of each of the cylinders relative to its associated cylinder by means of one and the same cam guide device. In practice the afore-mentioned regulation is 20 effected by the said one cam guide device being axially displaceable along the drive shaft in a sliding abutment on this, and is adjustable within a limited length of the drive shaft, by means of said separately regulatable control arrangement. 25 Consequently by adjusting the cam guide arrangement for the one piston in each cylinder axially along the drive shaft the compression ratio adjusts at the same time in each cylinder with a regulation via one and the same common control arrangement. 30 More specifically one has according to the invention made it possible to regulate the compression ratio for the cylinders of the engine as a whole, by means of for instance only the one cam guide device, each of the cam guide devices being common to all cylinders of the engine. 35 Alternatively to regulating the position for only the one cam guide device, it is possible to regulate the WU 95/49436 PCT/INU95/UUIZb 5 position for each of the cam guide devices synchronously or individually. But by regulating the position only for the one cam guide device the regulation arrangement is rendered 5 especially simple. In addition with such an arrangement of the one cam guide device other significant advantages can be obtained in the general function of the engine, as will be described further below. According to the invention there are consequently 10 possibilities of regulating the working volume between pistons of the cylinders as required, that is to say during use, and particularly during cold start of the engine and back to normal operation after the engine is run sufficiently warm. According to the invention the 15 compression ratio can consequently be regulated by regulating the mutual spacing between the pistons in each cylinder, by quite simply regulating the relative spacing between the cam guide devices. It is possible hereby to regulate the compression ratio of the cylinders of the 20 engine directly as required, independently of the concrete design of the cam guide devices in the finally manufactured condition of the engine. A favourably practical solution according to the invention consists in that the control arrangement is 25 regulatable by means of pressure oil. Preferably the control arrangement comprises an annular pressure oil chamber, which is defined between the drive shaft and the cam guide device, while a piston forming compression simulator projects from the cam guide 30 device radially inwardly into the pressure oil chamber and divides this into two chamber portions, that is to say one on each side of the compression simulator, the chamber portions communicating with their respective mutually adapted pressure oil circuits. 35 It is preferred that the cam guide device is fast connected for rotation with the drive shaft and that the compression simulator is passed through, parallel to the WU Y9i/Y'I3D I'CI/NU9I1OULO 6 axis of the drive shaft, by a set of driving bolts, which allow a certain axial movement of the compression simulator relative to the drive shaft, while the driving bolts are connected at their respective opposite ends to 5 the piston rod. It is especially interesting according to the invention to change the compression ratio in connection with the starting up of the engine, that is to say on cold start. It is furthermore interesting in addition to be 10 able to change the compression ratio during operation in order thereby to obtain a most favourable compression ratio possible during normal operation. Consequently it can be of interest to change the compression ratio during operation of the engine for various reasons. 15 It is preferred according to the invention that the one piston of the cylinder, which is under discussion to regulate the position of in the associated cylinder, constitutes a piston which controls opening and closing of exhaust ports of the cylinder. 20 At the same time as the compression ratio is regulated between the pistons, there is hereby the possibility in addition to regulate the opening and closing sequence of the associated exhaust ports. Inter alia the flow-through passages of the exhaust 25 ports can hereby be defined as required. Further the moment of opening and closing of the exhaust ports can be displaced in relation to normal operation. When one starts with a cold motor, provision can be made for instance for the said one cam guide device to 30 occupy automatically, for example by temperature sensitisation, the outer position, where there is obtained the highest compression of the engine. This means for instance that the exhaust ports open somewhat delayed and are held open over a shorter period, than with normal 35 operation. On starting the engine there is consequently brought about automatically the achievement of the relatively highest compression at the moment there is the WU 9?5494i3 PCI/N U9?3/UI2b 7 greatest need for this and at the same time the exhaust ports are controlled in a favourable manner relative to the subsequent compression stroke, so that a high operative temperature is also obtained at a timely stage 5 during the operation. According to the invention the temperature in cylinders of the engine can be obtained by means of residual exhaust gases being held at a higher temperature level than otherwise possible. In other words there is obtained at the start of the engine a certain 10 checking of the emptying of the exhaust , that is to say less complete emptying of the hot exhaust gases from the working chamber of the cylinder. This means in turn that the working chamber is kept at a relatively high temperature in the starting up phase, at the same as one 15 gets in the following compression stroke the intended high compression and correspondingly rapidly obtains a high combustion temperature. Both effects are favourable on starting up the operation of the engine in cold conditions. 20 By means of thermosensors it can be automatically ensured if desired that the cam control be readjusted from a position having high compression to a position having equivalently lower compression, gradually as the engine is warmed up. If necessary extra regulating equipment can be 25 employed for manual adjustment of the compression level as required. The afore-mentioned situation is especially favourable in connection with the remaining regulation of the working conditions individually for the two pistons in 30 each cylinder. In this connection it is preferred that the respective cam guide devices of the two pistons, at least in certain portions of the "sine" - plane, are phase displaced relative to each other. Inter alia one can hereby achieve according to the 35 invention a favourable separate control of the exhaust ports via the one group of pistons and separate, favourable control of the scavenging air ports via the WU S/494J0 PCIT/INU98/UUlZO 8 other group of pistons via their respective separate cam guide devices. The positions which are determined for the cam guide devices axially along the drive shaft can be regulated 5 according to the invention as required singly, that is to say individually, or collectively, for instance during operation of the engine, while the phase displacement between the cam guide devices is determined during the manufacture of the engine by positioning the cam guide 10 devices relative to each other in the peripheral direction around the drive shaft. Consequently the opening and closing of the scavenging ports and the exhaust ports can for instance be achieved according to said phase displacement at different 15 moments and these moments can be determined by equivalent designing of the individual cam guide device. During operation according to the present invention the effect of the said phase displaced opening and closing of for instance the exhaust ports, which is controlled by 20 the one of the cam guide devices, can be oversteered to a certain degree, by changing the relative spacing between the cam guide devices, while during normal operation the conditions can be optimised with a sufficiently heated engine. 25 Further features of the present invention will be evident from the following description having regard to the accompanying drawings, which show some practical embodiments and in which: Fig. 1 shows a vertical section of an engine 30 according to the invention. Fig. la and lb show in a corresponding segment of Fig. 1 vital parts of the engine and illustrate in Fig. la pistons of the engine in a position with maximum mutual spacing and in Fig. lb pistons of the engine in a position 35 with minimal mutual spacing.

WO 98149436 PCTI/NU9/UUIZb 9 Fig. 2 shows schematically a first cross-section illustrated at one end of the cylinder of the engine in which there is shown a scavenging air intake. Fig. 3 shows schematically a second cross-section 5 illustrated at the other end of the cylinder of the engine, in which there is shown an exhaust outlet. Fig. 4a shows schematically in a third cross-section, the middle portion of the engine cylinder, where the fuel is supplied and the ignition of the fuel occurs, 10 illustrated in a first embodiment. Fig. 4b shows in a cross-section, which corresponds to Fig. 4a, the middle portion of the cylinder according to a second embodiment. Fig. 5a shows in longitudinal section a segment of 15 the engine according to Fig. lb. Fig. 5b shows a cam guide device with associated drive shaft, illustrated in longitudinal section with a segment of the engine according to Fig. lb. Fig. 5c shows a cross head in side view. 20 Fig. 5d and 5e show the cross head according to Fig. Sc seen respectively from above and below. Fig. 5f shows the piston rod seen in side view. Fig. 5g shows the piston rod according to Fig. 5f seen from above. 25 Fig. Sh shows a piston according to the invention in vertical section. Fig. 6 - 8 show schematically illustrated and spread in the plane of the drawing a general pattern of movement for a first of two pistons associated with each cylinder, 30 used in connection with a three cylinder engine, and illustrated in different angular positions relative to the rotary movement of the drive shaft. Fig. 6a shows schematically the principle for trans ferring motive forces between the roller of the piston rod 35 and an associated obliquely extending portion of a "sine" - plane.

WU 91/4940b CFT/NO98/UU126 10 Fig. 9 shows schematically illustrated and spread in the plane of the drawing a more detailed pattern of movement for two pistons of each cylinder, illustrated in different angular positions relative to the rotary 5 movement of the drive shaft, illustrated in connection with a five cylinder engine. Fig. 10 shows in a representation corresponding to Fig. 9, the pistons in respective positions relative to associated cylinders, in a subsequent working position. 10 Fig. 11 shows schematically a segment of a central portion of a "sine" - plan for two associated pistons of each cylinder. Fig. 12 shows a detailed curve contour for a "sine" plane for a first piston in each cylinder. 15 Fig. 13 shows a corresponding detailed curve contour for a "sine" - plan for a second piston in each cylinder. Fig. 14 shows a comparative compilation of the curve contours according to Fig. 12 and 13. 20 Fig. 15 shows in section and in longitudinal section an alternative construction of a cam guide device with associated pressure rollers arranged at the outer end of a piston rod. Fig. 16 shows the same alternative solution, as 25 illustrated in Fig. 15, shown in section in a direction radially outwards from the cam guide device. Fig. 17 and 18 show in elevation and in horizontal section respectively the guiding of the head portion of the piston rod along a pair of control bars extending 30 mutually in parallel. In connection with Fig. 1 a two cycle combustion engine 10 having internal combustion shall generally be referred to herein. Especially there shall be described such a motor 10 adapted according to a so-called "sine" 35 concept. In Fig. 1 there is illustrated in particular a combustion engine 10 according to the invention shown in cross-section and in a schematic manner.

WO98/49436 PCT/N098/00126 11 In Fig. 1 there is shown a combustion engine 10 having internal combustion, according to the invention, illustrated in cross-section and in a schematic manner. As an embodiment there is shown a two cycle combustion engine 5 10, but as mentioned the solution can also be applied to a four cycle engine, without the specific embodiment of this being described herein. According to the present invention there is specifically proposed a solution for changing the 0 compression ratio of the engine during use. The change of the compression ratio will however also be able to have an influence on remaining operating conditions of the engine as will be evident form the following description. The following description refers to different aspects 5 according to the invention which have direct or indirect significance for various functions of the engine and effects following from this. According to the invention an objective is inter alia a favourable control of the opening and closing of exhaust 0 ports 25 and scavenging ports 24 as will be described further below. Furthermore the aim is combustion in a specially defined combustion chamber K1, as will be described in more detail below. 5 In the illustrated embodiment a drive shaft is constructionally shown in the form of a drive stump shaft, which passes axially and centrally through the engine 10. The drive shaft 11 is provided with a first head portion 12a projecting radially outwards, which consti 0 tutes a first cam guide device, the drive shaft is further provided with a second head portion 12b projecting equivalently outwards, which constitutes a second cam guide device. The head portions/ the cam guide devices 12a,12b in 5 the illustrated embodiment are represented separately and are connected separately to the drive shaft 11 each with their fastening means.

WO98/49436 PCT/NO98/00126 12 The cam guide device 12a surrounds the drive shaft 11 at its one end lla and forms an end support against end surface llb of the drive shaft 11ii via a fastening flange 12a' and is stationarily secured to the drive shaft via 5 fastening screws 12a'' The cam guide device 12b surrounds a thickened portion lic of the drive shaft 11 at its opposite end portion lid. The cam guide device 12b is not, as is the cam guide device 12a directly secured to the drive shaft 0 11, but is on the other hand arranged axially displaceable a limited extent axially along the drive shaft 11, especially with the idea of being able to regulate the compression ratio in cylinders 21 of the engine 10 (only the one of a number of cylinders is shown in Fig. 1). 5 End portion lid (see Fig. 1 and 5a) of the drive shaft 11 forms a radially offset sleeve portion to which there is fastened cup-shaped carrying member 13. The carrying member 13 is provided with a fastening flange 13' which with fastening screws 13'' is secured to end portion 0 lid of the drive shaft 11. Between upper end surface 13a of the carrying member 13 and an opposite shoulder surface lie of the drive shaft 11 there is defined a pressure oil chamber 13b. In the pressure oil chamber 13b there is slidably received a compression simulator 12b' in the form 5 of a piston-forming guide flange, which projects from the inner side of the cam guide device radially inwards into the pressure oil chamber 13b for sliding abutment against the outer surface of the end portion lid. In order to prevent mutual turning between the cam 0 guide device 12b and the carrying member 13 and the drive shaft 11ii the guide flange 12b' is passed through by a series of guide pins 12' which are anchored in their respective bores in the end surface 13a of the carrying member 13 and in the shoulder surface lie of the drive 5 shaft 11i.

WO 9849430 PCI'/N095/UU0126 13 The pressure oil chamber 13b is supplied pressure oil and is drained of pressure oil via transverse ducts llf and llg through end portion lid of the drive shaft 11. An oil guide means 14, which is put axially inwards 5 into mutually aligned axial bores in the end portion lid of the drive shaft 11 and in fastening flange 13' of the carrying member 13, provides for pressure oil and return oil to be led to and from the ducts llf and llg via separate guide ducts 14a and 14b and adjacent annular [0 grooves 14a' and 14b' in the oil guide means 14. Control of pressure oil and return oil to an from the pressure oil chamber 13b on opposite sides of the compression simulator 12b' of the cam guide device 12b takes place from a remotely disposed commercially 15 conventional control arrangement, not shown further, in a manner not shown further. The drive shaft 11 is, as shown in Fig. 1, connected at opposite ends to equivalent drive shaft sleeves 15a and 15b. The sleeve 15a is fastened with fastening screws 15a' 20 to the cam guide device 12a, while the sleeve 15b is fastened with fastening screws 15b' to the carrying member 13. The sleeves 15a and 15b are rotatably mounted in a respective one of two opposite main support bearings 16a,16b, which are fastened at opposite ends of the engine 25 10 in a respective end cover 17a and 17b. As shown in Fig. 1, the end covers 17a and 17b are correspondingly fastened to an intermediate engine block 17 by means of fastening screws 17' Internally in the engine 10 a first lubricating oil 30 chamber 17c is defined between the end cover 17a and the engine block 17 and a second lubricating oil chamber 17d between the end cover 17b and the engine block 17. There is shown an extra cap 17e attached to the end cover 17b and an external oil conduit 17f between the lubricating 35 oil chamber 17c and the oil cap 17e. Further there is illustrated a suction strainer 17g connected to a lubricating oil conduit 17h which forms a communication WUY5/4Y4iO /I'INUY5/UUIO 14 between the lubricating oil chamber 17d and an external lubricating oil arrangement (not shown further). The oil guide means 14 is provided with a cover forming head portion 14c which is fastened to end cover 5 17b of the engine 10 with fastening screws 14c'. The cover-forming head portion 14c forms a sealing off relative to the lubricating oil chamber 17c endwise outside the support bearing 16b. Correspondingly there is fastened to the end cover 17a endwise outside the support 0 bearing 16a a sealing cover 14d with associated sealing ring 14e. The engine 10 is consequently generally constructed of a driven component, that is to say a rotatable component, and a driving component, that is to say a non .5 rotating component. The driven component comprises drive shaft 11 of the engine and carrying member 13 of the drive shaft and drive shaft sleeves 15a,15b plus the cam guide devices 12a and 12b, which are connected to the drive shaft 11. The driving, non-rotating component comprises .0 cylinders 21 of the engine with associated pistons 44,45. According to the present invention there is ensured a regulation of the compression ratio of the engine by effecting a regulation internally, that is to say mutually between the parts of the driven component. More .5 specifically the one cam guide device 12b is displaced axially backwards and forwards relative to the drive shaft 11, that is to say within the defined movement space in said pressure oil chamber 13a, which is determined by the guide flange 12b' and the part-chambers of the oil chamber 0 13a on opposite sides of the guide flange 12b'. In practice it is a question of a regulation length of some few millimetres for smaller motors and of some centimetres for larger engines. The respective volume differences of the associated working chambers have 35 however equivalent compression effects in the different engines.

WU Y/4430 F'I'C/INU98/UUIZO 15 For instance a stepwise or stepless regulation of the compression ratios can be considered according to need, for example adapted with graduated control of the cam guide device 12b to respective positions relative to the 5 drive shaft 11. The control can for example occur automatically by means of electronics known per se based on different temperature sensing equipment, and the like. Alternatively the control can occur by manual control via suitable regulation means, which are not shown further LO herein. By effecting the regulation of the cam guide device 12b in connection with the driven component of the engine, one avoids influence on the general control of the arrangement of associated piston 44, piston rod 48, main L5 support wheel 53 and auxiliary wheel 55, that is to say influence on the mechanical connection between the driving component and the driven component is avoided. On the other hand, with such a regulation of the cam guide device 12b, there is obtained an axial regulation 20 internally in the driving component, in such a way that the arrangement of piston 44, piston rod 48, main support wheel 53 and auxiliary wheel 55 can be displaced collectively via the cam guide device 12b relative to the associated cylinder 21, independently of the concrete 25 compression regulation in practice. In Fig. 1 and lb there is indicated by a broken line a centre space 44' between the piston heads of the pistons 44,45 at a normal compression ratio when the cam guide device 12b occupies the position illustrated in Fig. 1. By 30 the full line there is indicated a centre space 44'' between the piston heads of the pistons 44,45 when guide flange 12b' of the cam guide device 12b is pushed to the maximum upwardly against the shoulder surface lle of the piston rod 11. 35 The engine 10 is shown divided up into three stationary main components, that is to say a middle member, which constitutes the engine block 17 and two WO 98/49436 F /1NU9J/UU1Z6 16 cover-forming housing members 17a,17b which are arranged at a respective one of the ends of the engine 10. The housing members 17b, 17c are consequently adapted to cover their respective cam guide devices 12a,12b, support wheels 5 53 and 55 and their associated bearings in respective piston rods 48,49 at their respective end of the engine block 17. All the driving and driven components of the engine are consequently effectively enclosed in the engine 10 and received in an oil bath in the associated LO lubricating oil chambers 17c and 17d. In the engine block 17 in the illustrated embodiment, there is used in connection with a three cylinder engine, correspondingly designed with three peripherally separated engine cylinders 21. Only the one of the three cylinders L5 21 is shown in Fig. 1, la and lb. The three cylinders 21, which are placed around the drive shaft 11 with a mutual angular spacing of 1200, are designed according to the illustrated embodiment as separate cylinder-forming insert members, which are pushed 20 into an associated bore in the engine block 17. In each cylinder/ cylinder member 21 there is inserted a sleeve-shaped cylinder bushing 23. In the bushing 23 there is designed, as shown further in Fig. la and lb (see also Fig. 2 and 3), an annular series of 25 scavenging ports 24 at one end of the bushing 23 and an annular series of exhaust ports 25 at the other end of the bushing 23. Equivalently in wall 21a of the cylinder 21 there are arranged scavenging ports 26, which are radially aligned 30 with scavenging ports 24 of the bushing 23, as is shown in Fig. 2, while exhaust ports 27, which are radially aligned with exhaust ports 25 of the bushing 23, are equivalently designed in the cylinder wall 21a, as is shown in Fig. 3. In Fig. 1 there is shown an annular inlet duct 28 for 35 scavenging air, which surrounds the scavenging ports 26, and a scavenging air intake 29 lying radially outside.

WU Y5/494JO PCT/NO98/UU00126 17 As is shown in Fig. 2 the scavenging air ducts 28 extend at a significant oblique angle u relative to a radial plane A through the cylinder axis, specially adapted to put the scavenging air in a rotational path 38 5 internally in the cylinder 21, as is shown by an arrow B in Fig. 2. There is further shown in Fig. 1 an annular exhaust outlet duct 30, which surrounds the exhaust ports 27, plus an exhaust outlet 31 emptying radially outwards. L0 In Fig. 3 there is shown an equivalent oblique run of the exhaust ports 27 at an angle v relative to the radial plane A through the cylinder axis, specially adapted to lead the exhaust gases from the rotational path 38 internally in the cylinder in an equivalent rotational 15 path outwards from the cylinder 21, as is shown by an arrow C. The exhaust ports 27 are shown opening radially outwards to facilitate the outward flow of the exhaust gas from the cylinder 21 outwards towards the exhaust outlet duct 30. 20 In the conventionally known manner the scavenging air is used to push out exhaust gas from a preceding combustion phase in the cylinder, in addition to supplying fresh air for a subsequent combustion process in the cylinder. In this connection there is employed according 25 to the invention in a manner known per se a rotating air mass as shown by arrows 38 (see Fig. la and 4a) in working chamber K of the cylinder 21 in the compression stroke. In Fig. la,lb and 4a there is shown a fuel injector or nozzle 32 received in a cavity 33 in the cylinder wall 30 21a. The injector/nozzle 32 has a pointed end 32' (see Fig. 4a) projecting through a bore 34 in the cylinder wall 21a. The bore 34 passes through the cylinder wall 21a at an oblique angle, which is not marked further in Fig. 4a, but which corresponds to the angle u, as shown in Fig. 2. 35 The pointed end 32' projects further through a bore 35 in the bushing 23, in alignment with the bore 34. Mouth 36 (see Fig. 4a) of the nozzle/injector 32 is arranged so WU V5/4Y4.30 I'CI/NU5/UUIZO 18 that a jet 37 of fuel can be directed, as is shown in Fig. 4a, obliquely inwards in a rotating mass of air as shown by the arrows 38 in cylinder 21, just in front of a spark plug 39 (possibly ignition pin) arranged in a chamber zone 5 which forms a part of the combustion chamber K1 (see Fig. lb). In Fig. 4b there is shown an alternative construction of the solution as shown in Fig. 4a, there being employed in addition to a first fuel nozzle 32 and a first ignition 10 arrangement 39 a second fuel nozzle 32a and a second ignition arrangement 39a in one and the same disc-formed combustion chamber K1. Both the nozzles 32 and 32a are designed correspondingly as described with reference to Fig. 4a and both the ignition arrangements 39 and 39a are 15 corresponding as described with reference to Fig. 4a. In the nozzle 32a the associated components are designated with the reference designation "a" in addition. In the illustrated embodiment of Fig. 4b the nozzles 32,32a are shown mutually displaced an angular arc of 1800, 20 while the ignition arrangements 39,39a are correspondingly shown mutually displaced an angular arc of 1800. In practice the relative spacings can be altered as required, that is to say with different mutual spacings, for instance depending upon the point of time of the mutual 25 ignition, and the like. Further there is indicated in Fig. 1 a cooling water system for general cooling of the cylinder 21. The cooling water system comprises a cooling water intake not shown further having a first annular cooling water duct 41 and a 30 second annular cooling water duct 42. The ducts 41,42 are mutually connected via an annular series of axially extending connecting ducts 43 (see Fig. 3). The axially extending ducts 43 pass through the cylinder wall 21a in each intermediate zone 27a between the exhaust ports 27, 35 so that these zones 27a especially can be prevented from superheating by being subjected locally to a flowing through of cooling medium. The discharge of cooling water, WU V5/44.30 YL 171NU95/UUILO 19 which is not shown further in Fig. 1, is connected to the cooling water duct 42 remote from the cooling water intake, in a manner not shown further. Internally in the bushing 23 there are two axially 5 movable pistons 44,45 movable towards and away from each other. Just by the respective top 44a,45a of the piston and by the skirt edge 44b,45b of the piston there is arranged a set of piston fourths 46 in a manner known per se. The pistons 44,45 are movable synchronously towards 10 and away from each other in a two cycle engine system. Further details of the pistons are shown in Fig. 5h. The piston 44 is shown in the form of a relatively thin walled cap having top portion 44a and skirt portion 44b. Innermost in the internal hollow space of the piston there 15 is arranged a support disc 44c, thereafter follows a head member 48c for an associated piston rod 48, a support ring 44d and a clamping ring 44e. The head member 48c is provided with a convexly rounded top surface 48c' and concavely rounded off bottom 20 surface 48c'', while the support disc 44c is designed with an equivalent concavely rounded upper support surface 44c' and the support ring 44d is provided with a convexly rounded lower support surface 44d'. The head member 48c is consequently adapted to be tilted about a theoretical axis 25 relative to the piston controlled by the support surfaces 44c' and 44d'. By abutment against a shoulder portion 44f internally in the piston the ring 44e provides for the head member 48c - and thereby the piston rod 48 - having a certain degree of fit and thereby a certain possibility of 30 turning about said theoretical axis of the piston 44 during operation. The head member 48c is provided with a middle, sleeve-shaped carrying portion 48g having rib portions 48g' projecting laterally outwards which form a locking 35 engagement with equivalent cavities (not shown further) internally in the associated piston rod 48 (see Fig. la and lb).

WU 95/494 VLTNU9N/UU12O 20 In Fig. la the pistons 44,45 are shown in their equivalent, one outer position. This outer position, where there is a maximum spacing between the pistons 44,45, is designated herein generally as a dead point Oa for the 5 piston 44 and Ob for the piston 45. In the said dead point positions Oa and Ob the piston 44 uncovers the scavenging ports 24, while the piston 45 uncovers the exhaust ports 25, opening and closing of the scavenging ports 24 being controlled by positions of the LO piston 45 in the associated cylinder 21, while opening and closing of the exhaust ports 25 is controlled by positions of the piston 44 in the associated cylinder 21. This control will be described in more detail in what follows having regard to Fig. 12-14. L5 In addition this control will be described with additional effects having regard to the afore-mentioned regulation of the cam guide device 12b along the drive shaft 11. When the pistons 44,45 occupy their opposite outer 20 positions, where there is a minimal spacing between, as is shown in Fig. lb, these positions are usually designated as dead point positions. However according to the present invention the pistons 44,45 are stationary, that is to say without or broadly speaking without axial movement 25 relative to each other in and at these dead point positions. In that the pistons are held stationary not only in the dead point position, but also in adjacent portions of the respective "sine" - plane, as will be described further below, a volumetrically more or less 30 constant working chamber (combustion chamber) over a certain arcuate length can be ensured, that is to say over a considerably longer portion of the "sine" - plane than known hitherto. Consequently the pistons 44,45 are at rest or broadly 35 speaking at rest over a portion of the "sine" - plane, which is designated herein as a "dead portion" 4a for the piston 44 and as a "dead portion" 4b for the piston 45.

WO 98/49436 PCT/INU95/U12 21 Such dead portions 4a and 4b are further illustrated in Fig. 12 and 13. In said dead portions there is defined in the working chamber K a so-called "dead space", which herein (for 5 reasons which will be evident from what follows) is designated as the combustion chamber K1. The combustion chamber K1 is according to the invention mainly defined in and at a transition portion between the compression phase and expansion phase of the two cycle engine, as will be 10 described in more detail in what follows. During the expansion phase, that is to say from the position of the piston as shown in Fig. lb to the position of the piston as shown in Fig. la, the working chamber K is expanded from a minimum volume, shown by the combustion 15 chamber K1, gradually to a maximum volume, as shown in Fig. la and at said dead point 0a and Ob in Fig. 9 and 10, the combustion chamber K1 being gradually expanded with another chamber K2 in which the expansion and compression strokes of the pistons 44,45 take place. 20 According to the invention the combustion chamber K1 is defined to a considerable degree in said dead portion/dead space. In practice however the combustion can also continue a bit just outside said dead space, something which will be explained in more detail below. 25 In connection with the change of the compression ratio in the working chamber there can be a question in the position as shown in Fig. 10 about different volumes in the combustion chamber K1 all according to which regulation is effected during use of the engine. From the 30 above there should in that case also be a question about different volumes in the combustion chamber in the opposite position as shown in Fig. la. However one must be aware of the piston strokes for the individual piston 44,45 being precisely equally long 35 under all operative conditions, regardless of the compression ratio which must be employed.

WU 9V5494Jb PT'I/NU95/UUIZ6 22 According to the invention the combustion chamber K1 is defined to a considerable degree in said dead portion/ dead space. In practice however the combustion can also continue a bit just outside said dead space, something 5 which will be explained in more detail below. Each piston 44,45 is rigidly connected to its respective pipe-shaped piston rod 48 and 49, which is guided in a rectilinear movement via a so-called cross head control 50. The cross-head control 50 is arranged 10 partly in the engine block 17 and partly in the respective cover member 17a and 17b at the equivalent free outer end of the respective piston rod 48,49. The cross-head control 50, which is shown in detail in Fig. 5a, forms an axial guide for the piston rod 48 and 49 just within and just 15 outside the engine block 17. With reference to Fig. 5a there is a rotary pin 51 which is fastened at one end of the pipe-shaped piston rod 48 and which passes through the piston rod 48 crosswise, that is to say through its pipe hollow space 52. on a 20 middle portion 51a of the rotary pin 51, that is to say internally in said hollow space 52, there is rotatably mounted a main castor 53, while on one end portion 51b of the rotary pin 51 on the outwardly facing side 48a of the piston rod 48 there is rotatably mounted an auxiliary 25 castor 55. The main castor 53 comprises an inner hub portion 53a having a roller bearing 53b and an outer rim portion 53c. The rim portion 53c is provided with a double curved, that is to say ball sector-shaped roller surface 53c' 30 The auxiliary castor 55 has a construction corresponding to the main castor 53 and comprises an inner hub portion 55a, a middle roller bearing 55b and an outer rim portion 55c with ball sector-shaped roller surface 55c' 35 The main castor 53 is adapted to be rolled off along a roller surface 54 concavely curved in cross-section, which forms a part of a so-called "sine" - curve 54' as WU 95/4J43J PCT/NO98/0012Z 23 shown in Fig. 6 - 8. By employing a ball sector-shaped roller surface 53c', which rolls along an equivalently curved guide surface 54 of the cam guide device 12a and 12b, an effective support abutment can be ensured between 5 the castor 53 and the guide surface 54 under varying working conditions, and possibly with a somewhat obliquely disposed castor and/or obliquely disposed piston rod 48 (49), such as this being able to be permitted in the pivotable 10 mounting of the piston rod 48 in the piston 44, as shown in Fig. 5h. The "sine" - curve 54' is designed in the cam guide device 12a and 12b of the drive shaft on a side facing equivalently axially outwards from the intermediate 15 cylinder's 21. The auxiliary castor 55 is adapted to be rolled off against and along an equivalent, other "sine" curve (not shown further) concavely curved in cross section along a roller surface 56a in a roller path, which is designed in the cam guide device 12a (and 12b) radially 20 just within the roller surface 54. In the embodiment illustrated in Fig. 5a the "sine" curve 54a' is placed radially outermost, while the "sine" curve 56a' is placed in the cam guide device 12a a distance radially within the "sine" - curve 54a' 25 Alternatively the "sine" curve 54a' can be arranged radially within the "sine" - curve 56a' (in a manner not shown further). In each of the cam guide devices 12a and 12b there are designed a corresponding pair of "sine" - curves 54a', 30 56a' in a manner not shown further and each "sine" - curve can be provided with one or more "sine" - planes as required. In Fig. 1 schematic reference is made to a cam guide device 12a and 12b, while the details in the associated 35 "sine" - curves and "sine" planes are shown further in Fig. 9 - 14.

WO 9/4946 FI'CT/NU9/UUI2z3 24 The "sine" - concept Generally the "sine" - concept can be applied with an odd numbered number (1,3,5 etc.) of cylinders, while an even numbered (2,4,6 etc.) number of "sine" - planes is 5 employed and vice - versa. In a case where there is employed in each of the cam guide devices 12a and 12b a single "sine" - plane (having a "sine" - top and a "sine" - bottom), that is to say the "sine" - plane covers an angular arc of 3600, it is however 10 immaterial whether an odd numbered or even numbered number of cylinders is employed. Correspondingly with a number of two (or more) "sine" - planes there can for instance be employed a larger or smaller number of cylinders as required. 15 The said case with a single "sine" - plane can be especially of interest for use in engines running rapidly which are driven at speeds over 2000 rpm. According to the "sine' - concept the individual engine can be " internally " 20 geared with respect to speed, all according to which number of "sine" - tops and "sine" - bottoms is to be employed at each 3600 revolution of the drive shaft. In other words according to the "sine"- concept both engines can be built precisely in the revolutions per minute 25 region which is relevant for the individual application. Generally the series arranged cylinders of the engine, with associated pistons, of the illustrated embodiment are arranged in specific angular positions around the axis of the drive shaft, for instance with 30 mutually equal intermediate spaces along the "sine" plane or along the series of "sine" - planes ( the "sine" - curve). For example for a two cycle or four cycle engine numbering three cylinders (see Fig. 6), there can be 35 employed for each 3600 revolution two "sine" - tops and two "sine" - bottoms and four oblique surfaces lying between, that is to say two "sine" - planes are arranged after each WO 98/49456 PCT'I/ NU9/UU12O 25 other in each cam guide device 12a,12b. Consequently in a four cycle motor four cycles can be obtained for each of the two pistons of the three cylinders with each revolution of the drive shaft/cam guide devices and four 5 cycles for each of the two pistons of the three cylinders in a two cycle engine. Correspondingly for a two cycle engine numbering five cylinders, as is shown in Fig. 9 and 10, there can be employed, for each 3600 revolution, a "sine" - curve with 10 two "sine" - tops and two "sine" - bottoms and four oblique surfaces lying between, that is to say two "sine" planes arranged after each other in each cam guide device 12a,12b, so that in a two cycle engine four cycles are obtained for each of the two pistons of the five cylinders 15 with each revolution. The support rollers of the pistons are placed in the illustrated embodiment with equivalently equal angular intermediate spaces, that is to say in equivalent rotary angular positions along the "sine" - curve, so that they 20 are subjected one after the other to equivalent piston movements in equivalent positions along the respective "sine" - planes. The engine power is consequently transferred from the different pistons 44,45 one after the other via the 25 support rollers 53 in the axial direction for the drive shaft 11 via respective "sine" - curves each with their "sine" - plane, and the drive shaft 11 is thereby subjected to a compulsory rotation about its axis. This occurs by piston rods of the engine being moved parallel 30 to the longitudinal axis of the drive shaft and support rollers of the piston rods being forcibly rolled off along the "sine" - planes. The engine power is thereby transferred in an axial direction from support rollers of the piston rods to the "sine" - planes, which are forcibly 35 rotated together with the drive shaft 11 about its axis. In other words the transfer of motive power is obtained from an oscillating piston movement to a rotational WO 95/49430 PCT'/NO98/UUI126 26 movement of the drive shaft, the motive power being transferred directly from respective support rollers of the piston rods to "sine" - planes of the drive shaft. In Fig. 6a there-is schematically illustrated a 5 support roller 53 on an obliquely extending portion of a "sine" - curve 8a. Axial driving forces are shown from an associated piston 44 having piston rod 48 in the form of an arrow Fa and equivalently in a radial plane decomposed rotational forces transferred to the "sine" - plane 8a 10 shown by an arrow Fr. The rotational forces can be deduced from formula 2: Fr = Fa. tan 0. According to the invention one achieves inter alia by means of a particular design of the "sine" - plane 15 according to the invention, the expansion stroke of the pistons 44,45 - reckoned angularly relative to the rotational arc of the drive shaft - becoming larger than the compression stroke of the pistons 44,45. In spite of the different speeds of movement of the pistons in 20 opposite directions of movement, a relatively more uniform transfer of motive force to the drive shaft 11 can hereby be ensured and in addition a "more uniform", that is to say more vibration-free running of the engine. In Fig. 6 - 8 there is schematically shown the mode 25 of operation pf a three cylinder engine 10, in which only the one piston 44 is shown of the two cooperating pistons 44,45, illustrated in a planar spread condition along an associated "sine" - curve 54', which consists of two mutually succeeding "sine" - planes, plus the associated 30 main castor 53 of the associated one piston rod 48. In each of the Figures 6 - 8 there is schematically shown the associated one piston 44 in each of three cylinders 21 of the engine, an equivalent arrangement being employed for the piston 45 at the opposite end of the cylinders. For 35 the sake of clarity the cylinder 21 and the opposite piston 45 have been omitted from Fig. 6 - 8, only the piston 44, its piston rod 48 and its main castor 53 being WU 95/494br PIT/N U/UUIJ 27 shown. Axial movements of the piston 44 are illustrated by an arrow 57, which marks the compression stroke of the piston 44, and an arrow 58, which marks the expansion stroke of the piston 44. 5 The "sine" - curve 54' is shown with a lower roll path 54, which has a double "sine" - plane-shaped contour and which generally guides the movement of the main castor 53 in an axial direction, in that it more or less constantly effects a downwardly directed force from the 10 piston 44 via the main castor 53 towards the roll path 54 in the expansion stroke and an upwardly directed force from the roll path 54 via the main castor 53 towards the piston 44 in the compression stroke. The auxiliary castor 55 (not shown further in Fig. 6 - 8) is received with a 15 sure fit relative to an upper roll path 54b, as is shown in Fig. Sa. For illustrative reasons the said roll path 56b is shown vertically above the main castor 53 in Fig. 6 - 8, so as to indicate the maximum movement of the main castor in an axial direction relative to the roll path 54. 20 In practice it will be the auxiliary castor 55 which controls the possibility for movement of the main castor 53 axially relative to its roll path 54, as is shown in Fig. Sa. The auxiliary castor 55 is normally not active, but 25 will control movement of the piston 44 in an axial direction in the instances the main castor 53 has a tendency to raise itself from the cam-forming roll path 54. During operation lifting of the main castor 53 in an unintentional manner relative to the roll path 54 can 30 hereby be avoided. The roll path 56 for the auxiliary castor 55 is, as shown in Fig. 5, normally arranged in the fixed fit spacing from the associated roll path 56a. In Fig. 6 - 8 the sine curve 54' is shown with a first relatively steep and relatively rectilinear running 35 curve portion 60 and a subsequent, more or less arcuate, top-forming transition portion/dead portion 61 and a second relatively more gently extending, relatively WO 98/49430 PCT/NO9/UUI26 28 rectilinearly running curve portion 62 and a subsequent arcuate transition portion/dead portion 63. These curve contours are however not representative in detail of the curve contours which are employed according to the 5 invention, examples of the correct curve contours being shown in more detail in Fig. 12 and 13. The "sine" - curve 54' and the "sine" - plane 54 are shown in Fig. 6 - 8 with two tops 61 and two bottoms 63 and two pairs of curve portions 60,62. In Fig. 6 - 8 there 10 are illustrated three pistons 44 and their respective main castor 53 shown in equivalent positions along an associated "sine" - curve in mutually different, succeeding positions. It is evident from the drawing that the relatively short first curve portions 60 entail that 15 at all times only one main castor 53 will be found on the one short curve portion and two or roughly two main castors 53 on the two longer curve portions 62. In other words with the illustrated curve contour different forms of curve portions can be employed for the compression 20 stroke relative to the form of the curve portions for the expansion stroke. Inter alia one can hereby ensure that the two main castors 53 at all times overlap the expansion stroke, while the third main castor 53 forms a part of the compression stroke. In practice movement of the piston 44 25 is achieved with relatively greater speeds of movement in the axial direction in the compression stroke than in the expansion stroke. In themselves these different speeds of movement do not have a negative influence on the rotational movement of the drive shaft 11. On the contrary 30 it means one is able to observe that more uniform and less vibration-inducing movements in the engine can be obtained, with such an unsymmetrical design of the curve portions 60,62 relative to each other. Further there is obtained an increase of the time 35 which is relatively placed for disposition in the expansion stroke relative to the time which is reserved for the compression stroke.

WU 9?549460 PIT/NU98/UUI2Z 29 In a practical construction according to Fig. 6 - 8 there is chosen in a 1800 working sequence an arc length for the expansion stroke of about 1050 and an equivalent arc length for the compression stroke of about 750. But 5 actual arc lengths can for instance lie between 1100 and 950 when the expansion stroke is concerned and equivalently between 700 and 85' when the compression stroke is concerned. On using for instance a set of three cylinders 21 10 associated with three pairs of pistons 44,45, as is described above, two tops 61 and two bottoms 63 are employed for each 3600 revolution of the drive shaft 11, that is to say two expansion strokes per piston pair 44,45 per revolution. 15 On using for instance four pairs of pistons there can be correspondingly employed three tops and three bottoms, that is to say three expansion strokes per piston pair per revolution. In the embodiment according to Fig. 9 - 10 there is 20 discussed a five cylinder engine with five pairs of pistons, associated with two tops and two bottoms, that is to say with two expansion strokes per piston pair per revolution. Typical cam quide arrangement according to the invention 25 In what follows there will be described with reference to Fig. 9 and 10 in more detail a preferred embodiment of the "sine" - concept according to the invention in connection with a five cylinder, two cycle combustion engine with two associated, mutually differing 30 cam guide curves 8a and 8b, as shown in Fig. 9 and 10 and in Fig. 12 and 13. In Fig. 14 there is schematically shown a midmost, theoretical cam guide curve 8c, which shows the volume change of the working chamber K from a minimum, as shown 35 in the combustion chamber K1 in the dead zones 4a and 4b, to a maximum, as shown in the maximum working chamber K in the dead points Oa and Ob (see Fig. 9 - 10 and 12 - 14).

WU05/49430 FLT/1NUVf5/UUI2O 30 According to the invention the curve 8b, as is illustrated in Fig. 12 - 14, is shown at the dead point Ob phase-displaced an angle of rotation of 140 in front of the dead point Oa of the curve 8a. 5 The direction of rotation of the curves 8a and 8b, that is to say the direction of rotation of the drive shaft 11, is illustrated by the arrow E. In Fig. 9 and 10 there are schematically illustrated five cylinders 21-1, 21-2, 21-3, 21-4 and 21-5 and 0 belonging to two associated curves 8a and two curves 8b, shown spread in a schematically illustrating manner in one and the same plane. The five cylinders 21-1, 21-2, 21-3, 21-4 and 21-5 are shown in respective angular positions with a mutual angular space of 720, that is to say in 5 positions which are uniformly distributed around the axis of the rotary shaft 11. In Fig. 12 there is shown a first curve 8a, which covers an arc length of 1800 from a position 00/3600 to a position 1800. A corresponding curve 8a (see Fig. 9) passes 0 over a corresponding arc length of 180' from position 180' to position 3600. In other words two succeeding curves 8a for each 3600 revolution of the drive shaft. The curve 8a shows in position 00/3600 a first dead point Oa. From position 00 to a position 38.40 there is 5 shown a first transition portion la, which corresponds to a first part of a compression stroke and from position 38.40 to position 59.20 an obliquely (upwardly) extending rectilinear portion 2a, which corresponds to a main part of the compression stroke and from position 59.20 to a 0 position 750 a second transition portion 3a, which corresponds to a finishing part of the compression stroke. Thereafter from the position 750 to a position 850 there is shown in connection with a second dead point a rectilinear dead portion 4a, which is shown passing over 5 an arc length of 100. From the position 800 to a position 95.80 there is shown a transition portion 5a, from the position 95.80 to a WU Y5/4Y4JO i YLTINUY/UU1IZO 31 position 1600 an oblique downwardly extending, rectilinear portion 6a and from the position 1600 to a position 1800 a transition portion 7a. The three portions 5a,6a,7a together constitute an expansion portion. 5 In position 1800 is show anew the dead point Oa and thereafter the cam guide curve continues via a second corresponding curve 8a, from the position 1800 to the position 3600, that is to say with two curves 8a which together extend over an arc length of 3600. 10 In Fig. 13 there is shown an equivalent (mirror image) curve contour for the remaining curve 8b, shown with a dead point Ob and succeeding curve portion lb-7b. There is shown the dead point Ob in a position 3460, - the curve portion lb between the positions 3460 and 15 30, - the curve portion 2b between the positions 30 and 600, - the curve portion 3b between the positions 600 and 750, 20 - the curve portion 4b between the positions 750 and 800, - the curve portion 5b between the positions 80' and 101.50, - the curve portion 6b between the positions 101.50 25 and 1460 and - the curve portion 7b between the positions 146' and 1660, that is to say with the dead point Ob shown anew in the position 1660. The cam guide continues with a corresponding curve 8b 30 between the positions 1660 and 3460 (see Fig. 10). The first curve 8a (Fig. 12) controls opening (position 1600/340') and closing (position 2050/250) of exhaust ports 25. The second curve 8b (Fig. 13) control opening 35 (position 1460/3260) and closing (position 1850/50) of scavenging ports 24.

WU YI/47043O r./1U95/UU1LO 32 In Fig. 14 there is shown a phase-displacement of 140 between the dead points Oa and Ob, in the illustrated, schematic comparison of the curves 8a and 8b. Curve 8b, as 5 shown by broken lines in Fig. 14, is for comparative reasons shown in mirror image form relative to the curve 8a, which for its part is shown in full lines in Fig. 14. By chain lines there is shown the midmost, theoretical curve 8c, which illustrates a curve contour approximately 10 like or more like a mathematical "sine curve" - contour. In Fig. 9 and 10 there is shown the "sine" - plane 8b in a position 140 in front of the position for the "sine" plane 8a. The five said cylinders 21-1, 21-2, 21-3, 21-4 and 21-5 are shown in successive positions relative to the 15 associated "sine" plane and individually in successive working positions, as shown in the following diagram 1 and diagram 2. Diagram 1 with reference to Fig. 9 and Fiq. 12 - 13. 20 Cylinder No. Angle Working Exhaust Scavenging Curve Position Position Ports Ports Zone 8a/8b 25 21-1 3'/1830 compression closed open* la/lb 21-2 750/2550 compression closed closed 4a/4b 21-3 1470/3270 expansion closed closed 6a/7b 21-4 2190/390 compression closed closed 2a/2b 21-5 2910/1010 expansion closed closed 5b/6a 30 * The scavenging ports 24 open in position 1600/3400 and close in position 250/2050, that is to say the scaveng ing ports 24 are held open over an arc length of 450. 35 The exhaust ports 25 are held on the other hand open over an arc length of 390, that is to say over an arc length which is phase-displaced 140relative to the arc length in which the scavenging ports are open (see Fig. 14). 40 The scavenging ports 24 can consequently be open over an arc length of 200 (see the curve portions la - 3a in Fig. 12 and the single hatched section A' in Fig. 14) WU /494 4b F.T1NU9IUUIZOb 33 after the exhaust ports 25 are closed. This means that the compression chamber over the last-mentioned arc length of 20' can inter alia be supplied an excess of scavenging air, that is to say is overloaded with compressed air. 5 Diagram 2 with reference to Fiq. 10 and Fig. 12 - 13. Cylinder Angle Working Exhaust Scavenging Curve No. Position Position Ports Ports Zone 8a/8b LO 21-1 210/2010 compression closed closed la/2b 21-2 930/2730 expansion closed closed 5a/5b 21-3 1650/3450 expansion open** open* 7a/7b 15 21-4 2370/570 compression closed closed 2a/2b 21-5 3090/1290 expansion closed closed 6a/6b ** The exhaust ports open in position 1460/3260 and 20 close in position 1850/50, that is to say the exhaust ports 25 are open over an arc length of 390. From Fig. 14 it will be evident from the marked off, individual hatched sections B' that the exhaust ports 25 can be held open over an arc length of 140 before the 25 scavenging ports 24 open. The said sections A' and B' show the axial dimensions of the exhaust ports 25 and the axial dimensions of the scavenging ports 24 in a respective outer portion of the working chamber K. The ports 24 and 25 can thereby be 30 designed of equal height in each end of the working chamber K. The said height is shown in Fig. 12 -14 by X2. In an angle zone of 5' (from position 750 to position 80' - see especially Fig. 13) of the "sine" - plane 8b and in an angle zone of 100 (from position 750 to position 850 35 see especially Fig. 12) of curve Ba, the respective associated piston 44 and 45 is held pushed in to the maximum with a minimum spacing X of for instance 15 mm between the piston head 44a and the middle line of the working chamber. 40 With reference to Fig. 12 it must further be observed that over an arc length of 36.60, from position 59.20 to position 95.8 0 , the spacing between the piston heads is WU "/4Y4.50 PLT/1NUY5/UUI.ZO 34 changed relatively little. The spacing from the piston head 44a to the middle line 44' is changed from a minimum X = 15 mm (in the dead portion 750 - 800) to a 20 mm spacing (position 930 Fig. 13). 5 Correspondingly the spacing from the piston head to the middle line 44' is changed from a minimum X = 15 mm in the dead portion 750 - 800 to a 25 mm spacing in position 570 Fig. 13. Over said arc length of 36.60 the volume in the 10 combustion chamber K1 is kept approximately constant between the pistons 44,45. Combined effects of two phase-displaced "sine" - planes From Fig. 14 the contours of the respective two 15 curves 8a,8b, which are shown schematically in mirror image relative to each other will be evident. Curve 8b is shown real with a full line, while curve 8b is shown with a broken line, in mirror image about a middle axis between the pistons 44,45. The curve 8c shows a theoretical 20 midmost curve between the curves 8a,8b. It will be evident that the midmost curve 8c has a contour which lies more closely up to a sine curve contour than the contours of the curves 8a,8b individually. Consequently, even if one gets a relatively unsymmetrical contour in the curves 25 8a,8b mutually, a relatively symmetrical contour of the midmost curve 8c can be achieved. Fuel is injected: At the close of the compression phase in curve zone 3a and 3b the fuel is injected in a jet with a flow into 30 the rotating scavenging air current and is mixed/atomised effectively in the rotating scavenging air current. Ignition starter: Immediately after the injection of fuel that is to say at the close of the compression phase electronically 35 controlled ignition is initiated in curve zone 3a and 3b. Provision being made for effective rotation of the gas mixture of scavenging air and fuel in a fuel cloud past WU 95/494.50 PL1INUY/UUIZO 35 the ignition arrangement. According to the present invention one can aim with advantage at an ignition delay of 7 - 10% relative to the conventional ignition angle. Combustion phase 5 In the illustrated embodiment the combustion starts immediately after ignition and is accomplished mainly over a limited region in which the pistons roughly occupy a maximum pushed in position, that is to say at the close of the curve zone 3a,3b, that is to say in a region where the LO pistons are subjected to minimal axial movement. The combustion proceeds mainly or to a significant extent where the pistons 44,45 are held at rest in the inner dead portion 4a and 4b, that is to say over an arc length of 100 and 50respectively. However the combustion continues as L5 required to a greater or smaller degree in the following transition portion 5a,5b and in the main expansion portion 6a,6b, depending upon the speed of rotation of the rotary shaft. As a consequence of the rotating fuel cloud in the combustion chamber K1 in the dead portion 4a,4b and in 20 that one can keep the flame front relatively short in the disc-shaped combustion chamber K1, there can be ensured in all instances fuel ignition for a main bulk of the fuel cloud in the combustion chamber K1, that is to say within said dead portion 4a,4b. In practice the combustion 25 chamber can be allowed to be expanded to the portion 5a,5b just outside the dead portion 4a,4b with largely corresponding advantages in a defined volume of the working chamber K. Speed of combustion 30 The speed of combustion is as known of an order of magnitude of 20 - 25 meters per second. By the application of a double set of fuel nozzles and a corresponding double set of ignition arrangements distributed over each quarter of the peripheral angle of the working chamber (see Fig. 35 4b) the combustion area can be effectively covered over the whole of the disc-shaped combustion chamber K1. In WO98/49436 PCT/N098/00126 36 practice especially favourable combustion can thereby be achieved with relatively short flame lengths. Optimal combustion temperature: As a result of the concentrated ignition/combustion 5 zone 3a,3b which is defined in the chamber K just in front of the combustion chamber K1 and the region 5a,5b immediately after the combustion chamber K1, that is to say in a coherent region 3a - Sa and 3b - 5b, where the pistons 44,45 are at rest or largely at rest, it is 10 possible to increase the combustion temperature from usually about 1800'C to 3000 0 C. It is possible thereby to achieve an optimal (almost 100%) combustion of the fuel cloud even before the pistons 44,45 have commenced fully the expansion stroke, that is to say at the end of the 15 curve portions 5a,5b. Ceramic ring Provision is made for a ceramic ring, that is to say a ceramic coating applied in an annular zone of the working chamber K corresponding to a combustion region (3a 20 - 5a,3b,5b), so that high temperatures can be employed especially in the combustion chamber K1, but also in the following portion 5a,5b of the combustion region. The ceramic ring which is shown with a dimension as indicated by a broken line 70 in Fig. 12 - 14, comprises the whole 25 combustion chamber K1 and is in addition extended further outwards in the combustion chamber over a distance 13. Introductory Expansion Stroke After at least considerable portions of the fuel are consumed in the afore-mentioned combustion region (3a 30 5a, 3b,5b) and one has just started the expansion stroke there are generally optimal motive forces. More specifically this means that by way of the cam guide along the curves 8a and 8b there is obtained an optimal driving moment immediately the expansion stroke commences in the 35 transition region 5a,5b and increases towards a maximum in the transition region 5a,5b. The driving moment is maintained largely constant in the continuation of the WO 98/49436 PC'INO98/0012b 37 expansion stroke (in the region 6a,6b) and at least in the beginning of this region, as a consequence of possible after burn of fuel in this region in spite of the volumetric expansion which occurs gradually in the chamber 5 K as the expansion stroke proceeds forward through this. Expansion Phase According to the illustrated embodiment the compression phase takes place relative to the curves 8a,8b under angles of inclination of between about 250 and about 10 360 in the respective two curves 8a and 8b, that is to say with a mean angle (see Fig. 14) of about 300. If desired the angles of inclination (and the mean angle) can for instance be increased to about 450 or more as required. The expansion phase takes place correspondingly in the 15 illustrated embodiment at between about 220 and 270 in the two curves 8a and 8b, that is to say while at a mean angle (see Fig. 14) of about 240. As a result of the relatively steep (mean) curve contour of 30' in the compression phase and the relatively 20 gentler contour 24' in the expansion phase, there is achieved a particularly favourable increase of the durability in time of the expansion stroke relative to the durability of the compression stroke. According to the invention one can by means of said 25 unsymmetrical relationship between the speed of movement in the compression stroke and the speed of movement in the expansion stroke, displace the start of the combustion process in the compression phase closer up to the inner dead point and thereby time-displace a larger part of the 30 combustion process to the beginning of the expansion phase, without this having negative consequences for the combustion. Consequently there can be achieved a better control and a more effective utilisation of the motive force of the fuel combustion in the expansion phase than 35 hitherto. Inter alia there can be displaced an otherwise possibly occurring, uncontrolled combustion from the compression phase over the dead point to the expansion WU Y~I45Y4JO PC1T/NUY/UUIZO 38 phase and thereby convert such " pressure points", which involve uncontrolled combustion in the compression phase, to useful work in the expansion phase. 5 By extending the expansion phase at the expense of the compression phase a relatively higher piston movement is obtained in the compression phase than in the expansion phase. This has an influence on each set of pistons of the combustion engine in every single working cycle. 10 Rotation effect in the working chamber There is established rotation of the gases in the working chamber by ejecting exhaust gases via obliquely disposed exhaust ports 25 (see Fig. 2) followed by the injection of scavenging air via the obliquely disposed 15 scavenging air ports 24 (see Fig. 3). There is set up thereby a rotating, that is to say helical gas flow path (see arrow 38 in cylinder 21 -1 in Fig. 9) which is maintained over the whole working cycle. The rotational effect is reactivated in the course of the working cycle, 20 that is to say during the injection, ignition and combustion phases. There is consequently supplied a new rotational effect to the gas flow 38 during transit in the working cycle by fuel injection via the nozzle 36 and subsequent 25 fuel ignition via the ignition arrangement 39, the attendant combustion producing a direction fixed flame front with an associated pressure wave front roughly coinciding with the gas flow 38 already established. The rotational effect is consequently maintained during the 30 whole compression stroke and is reactivated during transit by injecting fuel via an obliquely disposed nozzle jet 37, as shown in Fig. 4a, via a corresponding obliquely disposed nozzle mouth 36. Additional rotational effects are obtained in the combustion phase. 35 A still additional increase of the rotational effect can be obtained according to the construction as shown in Fig. 4b by the application of an extra (second) fuel WU 9V5/4940 PC TI/NUY8/UUIZO 39 nozzle 37a, which is disposed angularly displaced relative to the first fuel nozzle 37, and by the application of an extra ignition arrangement 39a, which is disposed angularly displaced relative to the first ignition 5 arrangement 39. When the exhaust ports 25 open again, on the termination of the working cycle, the exhaust gas is exhausted with a high speed of movement, that is to say with a high rotational speed, during exhaustion of exhaust gas via the said obliquely disposed exhaust ports. Further 10 the rotational effect for the exhaust gases is maintained immediately the obliquely disposed scavenging ports 24 open, so that the residues of the exhaust gases are scavenged with a rotational effect outwardly from he working chamber K at the close of the expansion phase and 15 the beginning of the compression phase. Thereafter the rotational effect is maintained, after closing of the exhaust ports, the scavenging ports being continued to be held open over a significant arc length. Regulation of the compression ratio of the engine during 20 operation According to the invention it is possible to regulate the volume between pistons 44,45 of the cylinder 21 by regulating the mutual spacing between the pistons 44,45. It is hereby possible to directly regulate the compression 25 ratio in the cylinder 21 as required, for instance during operation of the engine by means of a simple regulation technique adapted according to the "sine" - concept. It is especially interesting according to the invention to change the compression ratio in connection 30 with starting up the engine, that is to say on cold start, relative to a most favourable compression ratio possible during usual operation. But it can also be of interest to change the compression ratio during operation for various other reasons. 35 A constructional solution for such a regulation according to the invention is based on pressure oil controlled regulating technique. Alternatively there can WU 95/4943O PCT/NO98/UU126 40 be employed for instance electron-controlled regulating technique, which is not shown further herein, for regulating the compression ratio. Alternatively there can be employed a corresponding 5 regulating possibility also for the piston 45 by replacing the cam guide device 12a with a cam guide device correspondingly as shown for the cam guide device 12b. It is apparent according to the invention that it is possible to regulate the position of both pistons 44,45 in 10 the associated cylinder via their respective cam guide arrangement with their respective separate possibility of regulation, in a mutually independent manner. It is also apparent that the regulation of the position of the pistons in the cylinder can be effected 15 synchronously for the two pistons 44,45 or individually as required. In Fig. 15 and 16 there is shown schematically an alternative solution of certain details in a cam guide device, as it is referred to herein by the reference 20 numeral 112a, and of an associated piston rod, as shown by the reference numeral 148 as well as a pair of pressure spheres, as shown by the reference numerals 153 and 155. The cam quide device 112a: In the construction according to Fig. 1 the cam guide 25 device 12a is shown having a relatively space-demanding design with associated casters 53 and 55 arranged at the side of each other in the radial direction of the cam guide device 12a, that is to say with the one caster 53 arranged radially outside the remaining caster 55 and with 30 the associated "sine" - grooves 54,55c illustrated correspondingly radially separated on each of their radial projections In the alternative construction according to Fig. 15 and 16 the cam guide device 112a is shown with associated 35 pressure spheres 153, 155 arranged in succession in the axial direction of the cam guide device 112a, that is to say with a sphere on each respective side of an indivi- WO98/49436 PCTINO98/00126 41 dual, common projection, illustrated in the form of an intermediate annular flange 112. The annular flange 112 is shown with an upper "sine" - curve forming "sine" - groove 154 for guiding an upper pressure sphere 153, which forms 5 the main support sphere of the piston rod 148, and a lower "sine" - curve forming "sine" - groove 155a for guiding a lower pressure sphere 155, which forms the auxiliary support sphere of the piston rod 148. The grooves 154 and 155a have, as shown in Fig. 15, a laterally concavely 10 rounded form corresponding to the spherical contour of the spheres 153,155. The annular flange 112 is shown having a relatively low thickness, but the low thickness can be compensated for as to strength in that the annular flange 112 has in the peripheral direction a self-reinforcing 15 "sine" - curve contour, such as indicated by the obliquely extending section of the annular flange illustrated in Fig. 16. In Fig. 15 the annular flange 112 is shown segmentally in section, while in Fig. 16 there is shown in cross-section a peripherally locally defined segment of 20 the annular flange 112, seen from the inner side of the annular flange 112. There can be employed a largely corresponding design of the afore-mentioned details in both cam guide devices, that is to say also in the cam guide device not shown 25 further corresponding to the lower cam guide device according to Fig. 1. The piston rod 148: According to Fig. 1 a pipe-shaped, relatively voluminous piston rod 48 is shown, while in the 30 alternative embodiment according to Fig. 15 and 16 there is illustrated a slimmer, compact, rod-shaped piston rod 148 having a C-shaped head portion 148a with two mutually opposite sphere holders 148b,148c for a respective pressure sphere 153,155. 35 The piston rod 148 can in a manner not shown further be provided with external screw threads which cooperate with internal screw threads in the head portion, so that WO98/49436 PCT/N0O98/00126 42 the piston rod and thereby the associated sphere holder 148b can be adjusted into desired axial positions relative to the head portion 148a. This can inter alia facilitate the mounting of the sphere holder 148b and its associated 5 sphere 153 relative to the annular flange 112. In Fig. 16 the annular flange 112 is shown with a minimum thickness at obliquely extending portions of the annular flange, while the annular flange 112 can have in a manner not shown further a greater thickness at the peaks 10 and valleys of the "sine" -curve, so that a uniform or largely uniform distance can be ensured between the spheres 153,154 along the whole periphery of the annular flange. By the reference numeral 100 there is referred to 15 herein a lubricating oil intake, which internally in the C-shaped head portion 148a branches off into a first duct 101 to a lubricating oil outlet 102 in the upper sphere holder 148b and into a second duct 103 to a lubricating oil outlet 104 in the lower sphere holder 148c. 20 The pressure spheres 153,155: Instead of the casters 53,55 shown according to Fig. 1, which are mounted in ball bearings, pressure spheres 153,155 are shown according to Fig. 15 and 16. The pressure spheres 153,155 are mainly adapted to be rolled 25 relatively rectilinearly along the associated "sine" grooves 154,155a, but can in addition be permitted to be rolled sideways to a certain degree in the respective groove as required. The spheres 153 and 155 are designed identically, so that the sphere holders 148a,148b and 30 their associated sphere beds can also be designed mutually identically and so that the "sine" - curves 154,155a can also be designed mutually identically. The pressure spheres 153,155 are shown hollow and shell-shaped with a relatively low wall thickness. There 35 are obtained hereby pressure spheres of low weight and small volume, and in addition there is achieved a certain WU 95/4940 PCr /1NU98/UU12O6 43 elasticity in the sphere for locally relieving extreme pressure forces which arise in the sphere per se. In Fig. 17 and 18 a pair of guide rods 105,106 are shown which pass through internal guide grooves 107,108 5 along opposite sides of the head portion 148a of the piston rod 148.

Claims (9)

1. Arrangement ih a combustion engine (10) having 5 internal combustion, comprising a number of engine cylinders (21), which are arranged in an annular series around a common middle drive shaft (11) and which have cylinder axes running parallel to the drive shaft, each cylinder including a pair of pistons (44,45) movable 10 towards and away from each other and a common, inter mediate working chamber (K) for each pair of pistons, while each piston (44,45) is equipped with its respective axially movable piston rod (48,49), the free outer end of which forms via a support roller (53) support against its 15 respective curve-shaped, that is to say "sine" - curve shaped, cam guide device (12a,12b), which is arranged at each of opposite ends of the cylinder (21) and which controls movements of the piston relative to the associated cylinder, 20 characterised in that at least the one (44) of the two pistons (44,45) in each cylinder is regulatably adjustable axially in the cylinder for regulating the relative spacing between the pistons, especially for regulating the compression ratio 25 i) in the common working chamber (K) between the pistons.

2. Arrangement in accordance with claim 1, characterised in that the position of the piston (44,45) in the cylinder (21) is adapted to be determined via the associated cam 30 guide device (12a,12b) of the piston by means of a separately regulatable control arrangement (13b).

3. Arrangement in accordance with claim 2, characterised in that the said one cam guide device (12b) is axially 35 displaceable along the drive shaft (11) in a sliding abutment on this, and is adjustable within a limited WU V5/4940 PCI/NU9 /UUIZb 45 length of the drive shaft (11) by means of said separately regulatable control arrangement (13b).

4. Arrangement in accordance with claim 3, characterised in that 5 the control arrangement (13b) is regulatable by means of pressure oil.

5. Arrangement in accordance with claim 4, characterised in that the control arrangement comprises an annular pressure 10 oil chamber (13b), which is defined between the drive shaft (11) and the cam guide device (12b), and a piston forming compression simulator (12b'), which projects from the cam guide device (12b) radially inwardly into the pressure oil chamber (13a) and partitions this into two 15 part-chambers, that is to say one on each side of the compression simulator, the part-chambers communicating with their respective, mutually adapted pressure oil circuits.

6. Arrangement in accordance with one of the claims 20 1 - 5, characterised in that the cam guide device (12b) is fast connected for rotation with the drive shaft (11), the compression simulator (12b') being passed through parallel to the axis of the drive shaft (11) by a set of 25 driving bolts (12'), which allow a certain axial movement of the compression simulator (12b') relative to the drive shaft (11), while the driving bolts (12') are connected at their respective opposite ends to the drive shaft (11) and 30 connected to a carrying member (13) fastened to the drive shaft (11).

7. Arrangement in accordance with claim 6, characterised in that 35 the drive shaft (11) is axially extended at its outer end with a radially graduated end portion, which is WU I/4Y430 I/INUV5/UUIZO 46 rigidly connected to the carrying member (13) in the form of a cup-shaped end part, the pressure oil chamber (13b) being localised between the drive shaft (11) and the cup-shaped carrying 5 member (13).

8. Arrangement in accordance with claim 6 or 7, characterised in that an oil guide means (14), which projects axially through an axial bore in the cup-shaped carrier member 10 (13) and further inwardly into an axial bore in the drive shaft (11) aligned with that is provided with a pair of internal, axially extending pressure oil ducts (14a,14b), which empty radially outwards into their respective associated pressure oil rings (14a',14b') which communi 15 cate with a pressure oil duct (llf,llg) to respective part-chambers of the pressure oil chamber (13b).

9. Arrangement in accordance with one of the claims 1 - 8, characterised in that one piston (44) of the cylinder (21), which is in 20 question to regulate the position of in the associated cylinder, constitutes a piston which controls opening and closing of exhaust ports (24) of the cylinder.