WO2011042301A1

WO2011042301A1 - Thermal engine such as e.g. an internal combustion engine and/or steam engine

Info

Publication number: WO2011042301A1
Application number: PCT/EP2010/063956
Authority: WO
Inventors: Gert Joachim Reinhardt
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-10-08
Filing date: 2010-09-22
Publication date: 2011-04-14
Anticipated expiration: 2012-04-08
Also published as: DE102009048754A1

Abstract

A thermal engine comprises at least one drive means (10). The drive means (10) includes at least two pistons (16,18) arranged in respective cylinders (38,40), The thermal engine further comprises at least two rotary members (14,15) connected to a respective shaft (24,26). The rotary members (14,15) each comprise a sinusoidal force transmission surface (32,34). These force transmission surfaces (32,34) are formed with different sinusoidal structures.

Description

Thermal engine

such as e.g. an internal combustion engine and/or steam engine

The present invention relates to a thermal engine such as, e.g., an internal combustion engine and/or steam engine. Particularly, the thermal engine is provided as a generator.

Conventional internal combustion engines comprise a rotary member such as, e.g., a crankshaft. The rotary member is connected to usually several piston/cyiinder units for rotary driving. Said piston/cylinder units are arranged in series or in an anguiar configuration for forming an in-line engine or V-type engine. In such engines, the piston rods of the piston/cyiinder units extend in a plane oriented substantially vertically to the longitudinal axis of the crankshaft. The rotary member is further connected to a flywheel so as to guarantee a uniform rotary movement and to push back the piston in the cylinders for compression of the fuel in the combustion chamber.

In thermal engines designed as steam engines and steam turbines, water is heated in order to generate steam. Within expansion chambers, said steam will expand. This will cause a movement of the piston or the turbine wheel.

Turbines which are connected to a generator for generation of electric current may have an efficiency of about 40%. Further known are gas turbines which, when coupled to generator, will also reach an efficiency of about 40%, An increase of efficiency can be obtained by coupling a gas turbine and a steam turbine with each other. However, such combinations of gas and steam turbines are technically complex and tend to have a large constructional size.

Further, from WO 2007/014245, an interna! combustion engine is known wherein the crankshaft has been replaced by a sinusoidal disk. Force transmission onto said sinusoidal disk is performed via slide members. Said slide members are connected to two pistons so that a piston/cylinder unit is provided on each of the sinusoidal disk. The two mutually opposite piston/cylinder units are operative to effect a reciprocating movement of the two pistons, with corresponding force transmission to the sinusoidal disk. In spite of the minimized friction and the optimized design, the efficiency of this thermal engine wit!, for physical reasons, not surpass a maximum of 50-60% at best.

It is an object of the invention to provide a thermal engine which has a high efficiency and also a small constructional size.

The thermal engine according to the invention, which particularly is an internal combustion engine and/or a steam engine, comprises at ieast one drive means. Said drive means comprises at Ieast two pistons arranged in a cylinder. It is further possible to arrange only one respective piston in a cylinder. Also, however, a piston designed as a doub!e piston can be arranged in one common cylinder. In this case, an alternate expansion wit! occur on both sides of the double piston, being effective to move the piston. Preferably, a plurality of such drive means are provided. According to the invention, at Ieast two rotary members are provided, each of them particularly connected to a shaft of its own. Alternatively, two or more rotary members can be arranged on a common shaft. The rotary members comprise respectively one sinusoidal force transmission surface, wherein these force transmission surfaces have different sinusoidai structures. By the provision of at least two rotary members which have different sinusoidai structures, i.e. particularly aiso different amplitudes and/or frequencies, it is rendered possible to provide drive means operating with extreme effectiveness. According to the invention, a combustion can occur in one of the cylinders of the drive means, and a steam expansion in the other cylinder. In the process, according to the invention, the heat generated by the combustion occurring in one cylinder wiil be fed into the further cylinder chamber and will heat the steam in this chamber. The internal combustion engine can also be used in a different manner, e.g. for steam generation via heat exchangers and/or by burning the exhaust gases, the thus generated steam being then introduced into a steam expansion chamber. Also in this case, an additional combustion with extremely small residues can be performed in a post-combustion burner, wherein, according to a preferred embodiment, the resultant heat will be used for steam generation or for heating the steam.

With particular preference, the steam is provided in a closed circuit. It is especially preferred to always maintain the steam temperature at more than 100°C so as to avoid condensation. In this preferred embodiment, no condenser is required.

Preferably, the sinusoidal structure of the rotary members is configured to comprise a flattened portion at a dead center of the piston movement. Preferably, said flattened portion is fomed at an upper dead center of the piston movement. This has the consequence that, for a brief time, the piston will not move, with the particular effect that no compression will occur in the respective cylinder. In this manner, the outflow of the gas will be enhanced. Such a flattened portion is provided particularly in drive means of the type driven by combustion. The provision of said flattened portion allows for a reduction of exhaust residues. For further improvement of the efficiency of the thermal engine of the invention, it is provided, according to a first preferred further embodiment of the invention, that said at least one drive means comprises an inner piston/cylinder unit as well as an outer piston/cylinder unit. According to this embodiment, the inner cylinder in which the inner piston is arranged, is at least partially surrounded by the outer cylinder in which the outer piston is arranged. Thus, the outer piston has an annular cross section. Especially if one of the two piston/cylinder units, particularly the outer piston/cylinder unit, is formed as a steam expansion chamber, the heat which during combustion is generated within the inner cylinder will be advantageously introduced directly into the steam expansion chamber formed by the outer cylinder. By this multistage configuration according to the invention, a considerable increase of efficiency can be achieved. Efficiencies as high as 70-85% are attainable.

According to a further preferred embodiment which, with regard to the configuration of the piston/cylinder unit, represents an independent invention, there are provided an inner piston/cylinder unit as well as an outer piston/cylinder unit which is designed in the manner described above. In this special embodiment, the inner cylinder is formed as a steam expansion chamber. The outer cylinder serves as a steam compressor. Within the outer cylinder, the outer piston will thus increase the pressure of the steam, whereupon the steam will be supplied, via a connection opening, from the outer cylinder to the inner cylinder. The inner cylinder will thus receive steam at a high pressure which will then be further increased by the inner piston. In this manner, a considerable increase of efficiency is accomplished.

Optionally, the efficiency can be still further increased by providing a further cylinder surrounding said outer cylinder, said further cylinder again preferably including an annular piston. Also said further cylinder can be formed as a steam expansion chamber or also as a combustion chamber. With particular preference, the inner cylinder is formed as a combustion chamber. Said at least one drive means is preferably arranged between the rotor members. Particularly, a plurality of such drive means are provided which are arranged on a circular line. The drive means comprise at least two piston/cylinder units, with the pistons respectively moving in opposite directions. The pistons are connected, preferably via piston rods, to the mutually opposite rotary members or are arranged in abutment thereon. In this arrangement, the movements are independent from each other because neither the two pistons nor the two rotary members are connected to each other. According to a preferred embodiment, an inner piston will move at a relatively high frequency within the inner cylinder formed as a combustion chamber. An outer piston, which preferably is arranged within an outer cylinder formed as a steam chamber, will move at a lower frequency. Thereby, the relatively slow expansion of the steam is taken into consideration. Not only the frequency of the different sinusoidal structures but also the stroke can be adapted to the requirements of the individual piston/cyiinder units. Thus, for instance, pistons which are arranged in combustion chambers can be formed to have a shorter stroke. This is advantageous e.g. when a two-stroke combustion is provided in the combustion chambers. The outer cylinders surrounding the inner cylinders, which outer cylinders preferably are steam expansion chambers, preferably have a larger effective piston surface and/or a larger stroke while at the same time having a lower frequency.

Said plurality of drive means which preferably are arranged on a circular ring, can also be surrounded by further drive means which again are preferably arranged on a circular ring. It is preferred that two rotary members are provided on each side of the drive means. Said respective two rotary members are preferably arranged concentrically with each other, the outer rotary member surrounding the inner rotary member. The respective two or more rotary members can be fixedly attached to a common shaft or be each attached to separate shafts. According to a further preferred embodiment, the pistons can also be arranged as annular pistons which are concentric with the one shaft or both shafts. Particularly, in such an arrangement, a plurality of mutually concentric annular pistons are provided.

Herein, the individual annular pistons can be formed as double pistons. Such double pistons are arranged in a common cylinder, wherein a combustion or steam expansion chamber is arranged on both sides of the double piston. The expansion within the two mutually opposite chambers will occur alternately, thus causing the double piston to be reciprocated in the common cylinder. It can also be provided that two annular pistons are arranged opposite to each other. In this case, the two annular pistons have substantially the same diameter. The two pistons are arranged e.g. in separate, also annular cylinders, thus allowing for independent movement of these mutually opposite annular pistons. Further, a common expansion chamber can be provided between said mutually opposite pistons. By the expansion of combustion gas or steam in this common annular expansion chamber, the two mutually opposite annular pistons will be moved away from each other.

According to a preferred embodiment, these - particularly plural - annular piston/cylinder arrangements are arranged between two rotary members.

In all of the above-described embodiments, the piston/cylinder units can be designed according to the basic principles explained hereunder. Said pistons can be - according to one option - pistons which are arranged in an appertaining cylinder. Such pistons which are arranged in a corresponding cylinder, can be located opposite to each other. Between such mutually opposite pistons, a common combustion chamber can be arranged. Second, the pistons can be configured as double pistons so that an expansion chamber is arranged on each side of the piston, wherein the double piston will be reciprocated by alternate expansion of the combustion gas or the steam. Herein, the individual pistons and the appertaining cylinders can be annular. Such annular piston/cyiinder units can be arranged coaxiaily with the one or two shafts. Further, individual piston/cylinder units can be provided on a circle arranged concentrically with said one or two shafts. Of course, the different embodiments of the piston/cylinder units can be combined with each other. Particularly, annular piston/cylinder units arranged concentrically with said at least one shaft, can be surrounded by individual - optionally even differently designed - piston/cylinder units which are again arranged on a concentric circular line.

According to a particularly preferred embodiment, the pistons at least partially have a different stroke. In this regard, it is preferred that, with substantially identical cross-sectional area, the stroke of a steam piston is larger than the stroke of a combustion piston. Further, it is possible to operate the steam pistons at least partially with different steam temperatures.

In the above described preferred embodiments of the invention, the rotary members are preferably substantially cylindrical, wherein the edge of the circular annular cylinder that faces inwardly in the direction of the drive means, will form the force transmission surface. The transmission surface herein is arranged substantially vertically to the shaft to which the corresponding rotary member is connected. If two mutually opposite rotary members are provided, the two shafts are preferably in alignment with each other. In case that a plurality of rotary members are provided on one or both sides of the drive means and these rotary members are each connected to a separate shaft, it is preferred that the shafts are arranged concentrically with each other.

According to a particularly preferred embodiment, at least two of the force transmission surfaces have different sinusoidal structures. This, however, is a preferred optional embodiment of the invention. Irrespective of the design of the sinusoidal structures, preferred embodiments of the invention are to be seen particularly also in the arrangement and/or the design of the piston/cylinder units.

In order to obtain the highest possible efficiency, particularly above 60% and preferably above 70%, an essential aspect of the invention resides in that the thermal engine can be given an extremely compact design. In a particularly preferred embodiment in which energy conversion by combustion is combined with energy conversion by steam, this will aliow for high degrees of efficiency. This is primarily the case because the combustion heat can be used for steam generation in different manners. Due to the compact design, an immediate heating of the steam cylinders and the steam pistons will occur already by the heat generated in the combustion chambers. Further, the exhaust gases generated during combustion can be used for steam generation. This is possible, on the one hand, by heat exchangers and, on the other hand, by burning the exhaust gases and using the resultant heat for steam generation. Burning the exhaust gases has the advantage that the exhaust gases will be purified.

The thermal engine of the invention preferably comprises closed expansion chambers. This, for instance, has the considerable advantage that the exhaust gases can be used in a simple manner for steam generation, in contrast to a conventional turbine with an open combustion chamber. For the steam expansion chambers, a circuit can be provided so that the steam which has cooled down after expansion will be heated again by the next expansion phase. In this manner, use is made of the residual heat stored in the steam.

Preferably, the thermal engine is coupled to a voltage generating device, thus forming a generator.

Preferred embodiments of the invention will be explained in greater detail hereunder with reference to the accompanying drawings. In the drawings, the following is shown :

Figure 1 is a schematic perspective view of the basic configuration of the thermal engine of the invention, partially shown in section,

Figure 2 is a schematic perspective view of different rotary members arranged concentrically with each other,

Figure 3 is a schematic perspective exploded view of the drive means used in the arrangement according to Figure 1,

Figure 4 is a schematic perspective exploded view of a further embodiment of the drive means,

Figure 5 is a schematic perspective exploded view of a further embodiment comprising a plurality of drive means arranged coaxially to a common shaft, and

Figure 6 is a schematic view of a further embodiment of the invention.

The thermal engine of the invention, which in the illustrated embodiment is a combination of a combustion engine and a steam engine, comprises a plurality of drive means 10. Said drive means 10, which are fixed to housing members 12, are arranged between two rotary members 14,15. In the illustrated embodiment, each drive means 10 comprises an inner piston 16 and an outer piston 18. Said inner piston 16 is connected to a piston rod 20 cooperating with the rotary member 14 on the right-hand side in Fig. 1. Said outer piston 18 is connected to a piston rod 22 cooperating with the rotary member 15 on the left side in Fig. 1.

The two rotary members 14, 15 are each tightly connected to a respective separate shaft 24,26, Via respective bearings 28, each of said two shafts 24,26 is rotatably supported, on the one hand, in said housing 12 and, on the other hand, in a housing which is not shown. The two shafts 24,26 rotate with different speeds and, via gears 30 and a transmission, not shown, are adapted to act e.g. on a common output shaft.

The two rotary members 14, 15 each have a circular cylindrical base shape, wherein that edge which is facing in the direction of the drive means 10 is effective as a force transmission surface 32,34. The piston rods 20,22 are arranged in abutment on the force transmission surfaces 32,34 via slide rings 36.

Rotary member 14 comprises a sinusoidal force transmission surface with two maxima and two minima, or two peaks and two troughs. Thereby, the movement of the pistons 16 and respectively of the piston rods 20 connected to the pistons 16 will be converted into a rotary movement of shaft 24,

Also the rotary member 15 on the left side in Fig. 1 has a substantially sinusoidal force transmission surface 34, the latter comprising only one maximum and one minimum. By the radial movement of the pistons 16 and respectively of the piston rods 22 connected to the pistons 16, also shaft 26 is caused to rotate, with the rotational speed of shaft 26 being different from that of shaft 24,

According to a particularly preferred embodiment of the invention, a plurality of drive means 10 are arranged not only on one ring as shown in Fig. 1, but on a plurality of mutually concentric rings. In such an embodiment, there are also provided a plurality of rotary members which again are concentric with each other. These rotary members can be arranged and designed in the manner schematically shown in Fig. 2. The three rotary members 15a, 15b and 15c illustrated in Fig. 2 are arranged concentrically with each other, wherein a shaft 24 (Fig, 1) is fixedly connected to all of said three rotary members. Said three rotary members 15a, 15b and 15c comprise different sinusoidal structures. These have different amplitudes and different frequencies. As a consequence, the individual rotary members 15a, 15b and 15c can be driven by drive means operated by gas expansion or by drive means operated by steam expansion. Further, the cup-shaped rotary members 15a, 15b and 15c can each comprise a flattened portion in the region of a minimum. Effected thereby is a brief standstill of the piston and thus a better combustion. An example of such an arrangement is illustrated at 17 in Fig. 2, wherein the flattened portion itself is not shown.

An essential element of the invention consists in the drive means designed according to the invention. As best seen in Fig. 3, the inner piston 16 is arranged within an inner cylinder 38. This cylinder 38 is arranged within a cylinder 40, or the outer cylinder 40 at least partially surrounds the inner cylinder 38, Within outer cylinder 40, also the outer piston 18 is arranged. The piston is formed with a bore 42 so that, depending on the position of piston 18, the latter will surround the inner cylinder 38. Thus, piston 18 comprises an annular region.

It is preferred that the inner cylinder 38 forms a combustion chamber 44 and the outer cylinder 40 forms a steam expansion chamber 46.

Since the inner cylinder 38 forms a combustion chamber 44, the heat generated during combustion will be supplied via the wall of cylinder 38 to said steam expansion chamber 46, thus serving for heating the steam. Since the expansion of steam will occur considerabiy more slowly than the expansion of a gas-air mixture, piston 16 will move with a distinctly higher frequency than piston 18. In correspondence thereto, also the rotary speeds of the rotary members 14,15 are different. Since the inner cylinder 16 will thus move more frequently than cylinder 18, the heat generated in combustion chamber 44 in each combustion cycle will be dissipated into the wall 38 or into a space provided within wall 38. Thus, wall 38 has a buffering function and will release the stored energy to the steam in expansion chamber 46. According to a further embodiment of the drive means 10 (Fig. 4), a total of three piston/cylinder units are provided. In addition to the piston/cylinder units described in connection with Fig. 3, there is provided a further piston 48 which surrounds the cylinder 40. Said piston 48 has a circular annu!ar cross section, with piston 18 being arranged in an opening 50 of piston 48. The pistons 18,48 are arranged coaxtally with each other. Piston 48 is arranged in a cylinder 52. Preferably, a steam expansion chamber 54 is provided between the two walls of cylinders 40 and 52. Thus, the movement of piston 48 will occur corresponding to the movement of piston 18 as a result of the expansion of steam. In the illustrated embodiment, the linear movement of piston 48 is transmitted, via two piston rods 22 and slide rings 36 connected to said piston rods 22, onto a further force transmission surface, not shown, and thus will be converted into a rotary movement. Said second force transmission surface itself is provided on a corresponding rotary member, wherein this rotary member is arranged in such a manner that two force transmission surfaces are provided. A first force transmission surface is arranged outside rotary member 15, and a second force transmission surface is arranged within rotary member 15. Thereby, uniform transmission of forces can be realized. The rotary member correspondingly driven by piston 48 can be fixedly connected to shaft 26 or to another shaft.

In the context of a further embodiment of the invention shown in Fig. 5, components similar or identical to those described above are identified by the same reference numerals.

An essential difference from the embodiment depicted in Fig. 1 resides in that a common shaft 56 is provided. Corresponding to the embodiment shown in Fig. 1, the two ends of shaft 56 are connected to a rotary member 14,15. Also in this embodiment, however, said common shaft 56 can be replaced by two separate shafts 24,26 as in the embodiment shown in Fig. 1. In each case, however, force transmission is performed to rotary members of a basic design corresponding to that of rotary members 14, 15 (Fig. 1), wherein the sinusoidal structure is adapted to the piston/cylinder units, particularly to their stroke and cycle. As described hereunder, a special embodiment comprises a plurality of mutually concentric drive means 10. For each concentric drive means, a rotary member is provided on both sides of shaft 56 so that, on each side of shaft 56, a plurality of rotary members are provided which also here are arranged concentrically with each other and which are connected to shaft 56. in the embodiment shown in Fig. 5, a first, inner drive means 10 comprises an annuiar piston 58. Piston 58 is formed as a double piston and thus is arranged in a common cylinder 60. Thus, said double piston 58 will be reciprocated parallel to shaft 56 as a result of expansions taking place in cylinder 60 alternately on both sides of double piston 58. Piston 58 is connected to at least two piston rods 20,22 per side. Said piston rods 20,22 are arranged regularly. The piston rods 20,22 transmit the linear movement via slide rings 36 onto a first inner rotary member fixedly connected to shaft 56.

A further double piston 62 of a larger diameter is arranged concentrically to double piston 58. Within a common cylinder 64, this double piston 62 will be reciprocated by corresponding alternate expansion on both sides of double piston 62. Corresponding to said inner double piston 58, also double piston 62 comprises a plurality of piston rods 20,22 on each side.

In the illustrated embodiment, the outer drive means 10 is a likewise annular piston/cylinder unit, wherein mutually opposite pistons 70 are arranged in mutually opposite cylinders 66. In accordance thereto, the annular pistons 70 arranged in their respective cylinders 66 will be moved independently of each other, wherein the individual pistons 70 are arranged opposite to each other. Optionally, the partition wall 68 between the cylinders 66 can be omitted so that the mutually opposite annuiar pistons 70 have a common expansion chamber and thus, under the effect to an expansion, will be moved away from each other within this chamber. The mutually opposite pistons 70, of which only one is shown in Fig. 5, are again provided with piston rods. In the illustrated embodiment, a double piston rod 71 is shown. In connection with the rotary members, said double piston rod wii! force a movement of the pistons 70 in both moving directions. Of course, instead of said double piston rod 71, also a conventional piston rod 22 can be connected to piston 70.

Particularly said inner drive means are combustion chambers in which e.g. a gas expansion will take place. According to a preferred embodiment, farther outward drive means, particularly said outer drive means, will be operated by steam. For enhanced efficiency, the steam generation takes place within an internal cylindrical steam generation chamber 72, the latter preferably directly surrounding the shaft 56. Thus, the massive heat which herein is generated upon expansion in the adjacent drive means will be directly used for steam generation. Via conduits 74, the steam will be supplied into the cylinders 66. Via further conduits 76, the steam which after expansion has cooled within cylinder 66 wii! be returned into said steam generation chamber 72.

Of course, the above described embodiments can also be combined with each other. Thus, for instance, a plurality of further drive means 10 of the type shown e.g. in Figs. 1 to 3 could be arranged on a coaxial ring.

According to a further preferred embodiment (Fig. 6), said drive means 10 are arranged in a star-shaped configuration and surrounded by a rotation member 82. Thus, said rotation member 82 is not cup-shaped but surrounds the drive means 10. Within rotation member 82, three or more drive means, arranged in a star-shaped configuration relative to each other, can be provided. In principle, it is possible to provide the drive means in the form of conventional piston/cylinder units operated by gas and/or steam. Particularly, there can be provided piston/cylinder units of the type described with reference to Figs. 3 and 4. According to the particularly preferred embodiment shown in Fig. 6, however, a further inventive design of the drive means 10 is provided. The drive means 10 shown in Fig. 6 comprise an inner piston 16 within a cylinder 38. Particularly, the three cylinders 38 arranged in a star-shaped configuration together form a common steam expansion chamber 44, Supply of steam to said steam expansion chamber 44 takes place via connection openings 80. These connection openings 80 are connected to an outer cylinder 40 surrounding the inner cylinder 38, and respectively to the compression chamber 46 of the outer cylinder. With the aid of compression pistons 84 arranged in cylinder chamber 46, the steam will be compressed, whereupon the steam wii! be conveyed into steam expansion chamber 44 via said connection openings 80.

Said compression pistons 84 are connected, via piston rods, not shown, to the rear rotary member 82 in Fig. 6 and to a third rotary member arranged before the cross-sectionaily shown rotary member 82. Thus, the piston rods of the pistons 16 are connected to an intermediate rotary member 82, and the piston rods of the annular pistons 84 are connected to a rotary member 82 which, relative to the plane of the drawing in Fig. 6, is arranged before and behind said intermediate rotary member.

In the illustrated embodiment, the rotary members 82 comprise a sinusoidal structure with a flattened portion 78. Thereby, a brief standstill of the pistons 16 in the upper dead center can be effected. Instead of or in addition to said flattened portion 78, it can also be provided that, in the direction of rotation of the rotary members, a flank before the upper dead center is flatter than the flank of the rotary member behind the dead center. This wii! have the same effect.

Further, via said connection openings 80, pressurized air can be supplied into the expansion chamber 44. The supply of steam or gas into expansion chamber 44 wili then be performed via a further opening, not shown. Operation of the compression pistons 84 is effected preferably by supply of steam into the expansion chambers provided externally of the pistons 84.

Irrespective of the type of the drive means 10 provided in the embodiment shown in Fig . 6, a plurality of rotary members 82 can be provided behind each other which will cooperate respectively with drive means arranged in a star- shaped configuration. Said rotary members 82 are connected to a drive shaft, not shown.

The embodiment of the drive means described with reference to Fig. 6 can also be used in the other described embodiments of the invention (particularly Fig. 1).

Claims

A thermal engine, comprising

- at least one drive means (10) including at least two pistons ( 16,18) arranged in cylinders (38,40), and

- at least two rotary members ( 14,15) connected to a shaft (24,26) and having sinusoidal force transmission surfaces (32,34), preferably at least two of said force transmission surfaces (32,34) having different sinusoidal structures.

The thermal engine according to claim 1, characterized in that said sinusoida! structures are different in amplitude and/or frequency.

The thermal engine according to claim 1 or 2, characterized in that a plurality of drive means (10) are provided which are partially formed as combustion drive means and partially as steam drive means.

The thermal engine according to any one of claims 1 to 3, characterized in that said sinusoidal structure comprises a flattened portion (78) at a dead center of the piston movement.

The thermal engine according to any one of claims 1 to 4, characterized in that said drive means (10) comprises an inner cylinder (38) having an inner piston (16) arranged therein, and that said inner cylinder (38) is at least partially surrounded by an outer cylinder (40) having an outer piston ( 18) arranged therein.

6. The thermal engine according to claim 5, characterized in that said outer cylinder (40) is at least partially surrounded by at least one further cylinder, each of said further cylinders having a respective further piston arranged therein.

7. The thermal engine according to claim 5 or 6, characterized in that said inner cylinder (38) is formed as a combustion chamber (44).

8. The thermal engine according to any one of claims 5 to 7, characterized in that said outer cylinder (40) and optionally further cylinders are formed as a steam expansion chamber (46).

9. The thermal engine according to claim 5, 6 or 8, characterized in that said inner cylinder (38) is formed as a steam expansion chamber (44) and that the outer piston/cylinder unit ( 18,46) is formed as a steam compressor, said outer cylinder (46) being connected, for steam supply, to the inner cylinder (38) via a connection opening (80).

10. The thermal engine according to any one of claims 1 to 9, characterized in that the pistons are at least partially arranged as piston pairs comprising mutually opposite pistons.

11. The thermal engine according to claim 10, characterized in that said mutually opposite pistons are each arranged in a separate cylinder (64,66).

12. The thermal engine according to any one of claims 1 to 9, characterized in that the pistons (58,62) are at least partially formed as double pistons arranged for reciprocating movement in a common cylinder (60,64), a combustion chamber or a steam expansion chamber being arranged on both sides of said double piston (58,62).

13. The thermal engine according to any one of claims 1 to 12, characterized in that the pistons (16,18,58,62) partially have different strokes, wherein, with substantially identical cross-sectional area, the stroke of the steam piston is preferably larger than the stroke of a combustion piston,

14. The thermal engine according to any one of claims 1 to 13, characterized in that the steam pistons are at ieast partially operated at different steam temperatures,

15. The thermal engine according to any one of claims 1 to 14, characterized in that the generation of steam is at ieast partially performed by use of the combustion exhaust gases, particularly by heat exchangers and/or by burning the exhaust gases.

16. The thermal engine according to any one of claims 1 to 12, characterized in that said at Ieast one drive means (10) is arranged between said rotary members (14, 15),

17. The thermal engine according to any one of claims 1 to 16, characterized in that said rotary members (14,15) are connected to said pistons (16, 18) via piston rods (20,22),

18. The thermal engine according to any one of claims 1 to 17, characterized in that a plurality of drive means (10) are arranged on a circular ring .