EP2499337A2

EP2499337A2 - Free piston internal combustion engine

Info

Publication number: EP2499337A2
Application number: EP10773292A
Authority: EP
Inventors: Frank Heinrich
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-11-12
Filing date: 2010-10-25
Publication date: 2012-09-19
Also published as: DE102009052960A1; DE102009052960B4; WO2011057891A2; WO2011057891A3

Abstract

The invention relates to a piston (12, 22, 102, 212, 222) for a free piston internal combustion engine (1, 100, 200) having a first end face (122a) on the combustion chamber side and a cylinder axis (X) substantially perpendicular to the first combustion chamber side, wherein the first end face on the combustion chamber side is formed such that the piston can be set into rotation in a first direction of rotation about the cylinder axis by a gas impinging on the first end face on the combustion chamber side. The invention further relates to a piston arrangement having at least one first piston according to the invention and a first piston rod (30, 106, 216), wherein the at least one first piston (12, 212) is attached to the first piston rod, wherein in particular the first piston rod extends in the axial direction to the cylinder axis of the first piston. The invention finally relates to an internal combustion engine (1, 100, 200) having a piston arrangement according to the invention, displaceable back and forth in an engine housing in the axial direction, wherein each end face of the at least one first piston on the combustion chamber side and/or at least one second piston faces a combustion chamber (14a, 14b, 24a, 24b, 214a, 214b, 224a, 224b) and bounds same in an axial direction.

Description

Free-piston internal combustion engine

The invention relates to a piston for a free-piston internal combustion engine. Furthermore, the disclosure relates to a piston assembly. Finally, the disclosure relates to an internal combustion engine with such a reciprocating piston assembly. Usually, such internal combustion engines are known as free-piston engines.

For example, such an internal combustion engine from DE 80 20 723 Ul is known, which discloses a two-stroke internal combustion engine with a symmetrical, exposed stepped piston having at least two piston stages, which are each movably arranged in a combustion chamber provided with exhaust ports, each with a channel a pre-compressor room is connected. The piston stages between the combustion chambers are arranged axially inside.

From DE 35 18 982 Al a two-stroke internal combustion engine with exposed stepped piston is known, which has at least two arranged on a common piston rod piston stage and forms together with a multi-chamber cylinder two superchargers and at least two combustion chambers.

Furthermore, from DE 26 52 228 AI an engine with two spaced working chambers known, which are bounded by a cylinder wall, with a piston controlled by the pressure prevailing in the working chambers gas pressure and gas-tight against the cylinder wall in the working chamber is linearly movable, wherein Guide elements on the piston and the cylinder wall are arranged to control the piston in its axial movement in a rotational movement.

Although two-stroke free-piston engines have the advantages of compact lightweight construction, very high vibration and compression ratios, virtually no friction losses and operation with various fuels, these two-stroke free-piston engines have the disadvantage of being difficult to control due to a lack of fixed dead centers are. Furthermore, such an engine will stop at a misfire. In addition, the force is developed purely linear and systemic have two-stroke engines increased exhaust emissions. Free piston engines, in particular two-stroke free-piston engines, are typically more economical than gasoline or diesel engines.

The object of the invention is therefore to develop the generic piston and internal combustion engine such that they overcome the disadvantages of the prior art, In particular, the disadvantages are avoided without significantly increasing the design effort.

This object is achieved by a piston for a free piston internal combustion engine having a first combustion chamber side end face and a cylinder axis substantially perpendicular to the first combustion chamber end face, wherein the first combustion chamber end face is shaped such that the piston by a gas impinging on the first combustion chamber end face gas in a rotation in a first direction of rotation about the cylinder axis is displaceable.

The above subject is thus based on the surprising finding that a control can be substantially simplified by applying a controlled rotation of the piston and an internal combustion engine can be provided with a particularly high efficiency. So that the purely linear movement can be converted into a rotational movement in a simple and low-loss manner, the piston rod is offset with the piston by a rotation about its longitudinal axis. For this purpose, for example, the combustion chamber-side end face of a piston is not smooth, but similar to a turbine wheel provided with furrows and elevations extending from the center to the edge. In addition, in one embodiment, the piston rod can be axially extended and guided mechanically or electromagnetically. By the rotation of the piston is always known its exact position, for example, whether the piston is at a first axial extreme position or a second axial extreme position.

In particular, the above object is achieved in that the piston rod is rotated by a guide and the design of the piston end faces based on a turbine in rotation. In a typical embodiment, a defined career follows a recumbent eight.

In one embodiment, the piston may have a second combustion chamber-side end face which is substantially perpendicular to the cylinder axis and which is arranged axially opposite the first combustion chamber-side end face and is shaped such that the piston engages in a rotation about the cylinder axis through a gas impinging on the combustion chamber-side end face is displaceable, in particular in the first direction of rotation. Furthermore, an embodiment is characterized in that the first and the second combustion chamber-side end face are mirror-symmetrical to a radial plane perpendicular to the cylinder axis in the piston.

In a further embodiment, the at least one combustion chamber-side end face may have a radial reference plane, which is arranged in the combustion chamber direction at a maximum elevation, wherein the end face has at least one recess with respect to the end face, wherein the depressions are shaped in particular like a sawtooth.

Furthermore, it can be provided in one embodiment that the depressions extend in the radial direction, in particular in a star shape.

Further, the disclosure relates to a piston assembly having at least a first piston according to an embodiment of this disclosure and a first piston rod, wherein the at least one first piston is attached to the first piston rod, wherein in particular the first piston rod extends in the axial direction on the cylinder axis of the first piston.

It can be provided that the piston assembly comprises a second piston rod to which at least a second piston is attached, wherein in particular the second piston rod extends in the axial direction on the cylinder axis of the at least second piston, wherein preferably the first and second piston rod arranged parallel side by side are.

It may be provided in one embodiment that at least one second piston according to an embodiment of this disclosure is attached to the first piston rod and / or on the second piston rod, wherein in particular the first and second piston rod extends in the axial direction on the cylinder axis of the second piston , Preferably, the at least one first and the at least one second piston are spaced from each other to the first and second piston rod attached.

In an embodiment, the first piston rod and the second piston rod may be coupled such that the first piston rod is movable together with the second piston rod in the axial direction thereof.

Further, in one embodiment, the piston assembly may include a rotary coupling device for transmitting rotation of the first piston rod about its own axis to rotation of the second piston rod about its own axis, wherein in particular the rotary coupling device is a gear, a belt and / or a chain.

In a further embodiment, the first and / or second piston rod may have at least one fluid channel for a fuel-air mixture and / or exhaust gas, wherein in particular the first and / or second piston rod for each combustion chamber-side end face of a fixed to the respective piston rod at least a first and / or at least one second piston has at least one fluid channel for a fuel-air mixture and / or exhaust gas.

It can be provided in one embodiment, that the at least one fluid channel is arranged such that it at least temporarily fluid communication between a fuel-air mixture supply channel and adjacent to the combustion chamber side combustion chamber of the at least one first and / or second piston and / or between an exhaust duct and an adjacent to the combustion chamber side surface combustion chamber of the at least one first and / or second piston produces.

It can be provided that the at least one fluid channel extends in the axial direction, in particular in a straight line.

In a further embodiment, the at least one fluid channel may be a groove. In another embodiment, the fluid channel may be a bore.

Furthermore, this disclosure relates to an internal combustion engine having a piston assembly which can be moved back and forth in an axial direction in a motor housing according to an embodiment of this disclosure, wherein each combustion chamber end face of the at least one first piston and / or at least one second piston faces a combustion chamber and limits it in the axial direction ,

In one embodiment, the at least one first and / or at least one second piston can each be arranged in a working space, and the internal combustion engine have at least one guide sleeve, wherein at least one working space is limited in the radial direction by the at least one guide sleeve, on which the respective piston along, wherein the at least one guide sleeve at least one exhaust and / or fuel-air mixture supply port for at least one combustion chamber, in particular for each combustion chamber has. In one embodiment, at least one control sleeve is arranged in the radial direction about the at least one guide sleeve, wherein the at least one control sleeve has at least one exhaust gas and / or fuel-air mixture supply opening for at least one combustion chamber, in particular for each combustion chamber the internal combustion engine is set up such that the at least one exhaust gas and / or fuel-air mixture supply port of the control sleeve and the at least one exhaust gas and / or fuel-air mixture supply port of the guide sleeve can be arranged for at least one combustion chamber.

In one embodiment, the at least one guide sleeve and / or the at least one control sleeve are rotatable about the longitudinal axis. In this case, the rotational movement (s) can be synchronized and / or coupled, in particular with the rotation of the first and / or second piston rod.

In this case, in one embodiment, the at least one exhaust gas and / or fuel-air mixture supply opening of the at least one guide sleeve and the at least one control sleeve can be arranged such that at least two combustion chambers are in different cycles at the same time during operation.

In one embodiment, the at least one guide sleeve and / or the at least one control sleeve is coupled to the first and / or the second piston rod (30, 216, 226) in such a way to prevent rotation of the first piston rod and / or the second piston rod to transmit its own axis to a rotation at least one guide sleeve and / or the at least one control sleeve about its own axis.

For example, in one embodiment, the at least one guide sleeve and / or the at least one control sleeve can be movable in the axial direction.

In one embodiment, the internal combustion engine comprises at least one exhaust gas channel and at least one fuel-air mixture supply channel for each combustion chamber, wherein in particular the at least one exhaust gas channel and / or the at least one fuel mixture supply channel is or are limited by the piston rod.

It may be provided that the at least one fluid channel, the motor housing, the at least one exhaust passage of the at least one fuel-air mixture supply channel, the at least one guide sleeve and / or at least one control sleeve are formed such that the at least one fluid channel and / or the at least one exhaust and / or Fuel-air mixture supply port temporarily during operation of the internal combustion engine, a first fluid connection between the exhaust passage and the combustion chamber and temporarily establishes a second fluid connection between the fuel-air mixture supply passage and the combustion chamber.

It can be provided that the internal combustion engine is set up such that the first and second fluid connection can be produced simultaneously or in succession. For example, the fluid channel may be shaped to be in fluid communication with the exhaust passage and the fuel-air mixture supply passage simultaneously.

Furthermore, in one embodiment, it can be provided that the same fluid channel and / or the same exhaust gas and / or fuel-air mixture supply port produce the first fluid connection and the second fluid connection.

In one embodiment, the first fluid connection may be made at at least a first rotation angle range of rotation of the piston assembly and the second fluid connection at at least a second rotation angle range of rotation of the piston assembly, wherein the at least one first rotation angle range and the at least one second rotation angle range do not intersect.

Furthermore, it can be provided in one embodiment that the internal combustion engine is a four-stroke internal combustion engine.

In one embodiment, the internal combustion engine may include at least four combustion chambers and at least two pistons, wherein the fluid channels, the at least one guide sleeve and / or the at least one control sleeve, are formed such that in operation at the same time each clock occurs at least once.

Furthermore, in one embodiment it can be provided that at least one first guide element is arranged on the first and / or second piston rod and / or the piston skirt surface and at least one second guide element on the motor housing, wherein the first guide element interacts with the second guide element such that the Piston assembly is displaceable in an axial movement in a rotary motion. It may be provided that the cooperating guide elements are a groove and at least one projection, wherein in particular the at least one projection on the piston rod and / or piston skirt surface is arranged.

In one embodiment, the at least one groove may have two side walls whose spacing from one another defines a width of the groove, the groove being wider than the projection, in particular at least twice as wide as the projection, such that the projection does not contact the sidewalls through the groove is feasible.

It may be provided that the cooperating guide elements are a coil and / or magnets of an electric motor. In this case, in particular, the at least one magnet can be fastened to the piston arrangement.

Furthermore, it may be provided in one embodiment that, wherein the cooperating guide elements are formed such that in operation a complete rotation of the piston assembly is achieved after four cycles or a multiple of four cycles.

In one embodiment, the at least one combustion chamber-side end face of the at least one piston can be designed and cooperated in such a way that a complete rotation of the piston assembly is achieved after four cycles or a multiple of four cycles during proper operation.

Typically, a proper operation is an operation in which no misfire occurs or the engine is started so that the engine runs smoothly.

Further features and advantages of the invention will become apparent from the following description in which an embodiment of the invention with reference to schematic drawings will be explained in detail. Showing:

Fig. 1 is a schematic side view of an embodiment of a free-piston internal combustion engine;

Figures 2a to 2d show a schematic cross section at different times of an embodiment of a free piston engine;

Fig. 3 shows a guide for controlling a free-piston internal combustion engine; Fig. 4 is an enlarged view of a piston of an embodiment of a free piston internal combustion engine;

Fig. 5 shows a schematic cross section of another embodiment of a free-piston internal combustion engine;

Fig. 6a shows an embodiment of a developed guide sleeve for the free-piston internal combustion engine;

Fig. 6b shows an embodiment of a developed control sleeve for the free-piston internal combustion engine;

Fig. 7 is a schematic side cross-sectional view of one embodiment of a free piston internal combustion engine; and

FIG. 8 shows a schematic control gear of the free-piston internal combustion engine from FIG. 7.

1 shows a side view of a free-piston internal combustion engine 1, which comprises a first working chamber 10 in a first cylinder 11 and a second working chamber 20 in a second cylinder 21. In the first working chamber 10, a first piston 12 is arranged, which divides the first working chamber 10 into a first combustion chamber 14 a and a second combustion chamber 14 b on both sides of the piston 12. Also, in the second working chamber 20, a second piston 22 is arranged, which divides the second working chamber into a first combustion chamber 24a and a second combustion chamber 24b, which are arranged on both sides of the second piston 22.

The first piston 12 and the second piston 22 are connected to each other via a piston rod 30 in the axial direction of the pistons 12, 22. Thus, the piston rod 30 and the pistons 12, 22 have a common longitudinal axis X. The pistons are able to reciprocate in the axial direction in the respective working chamber 10, 20. As will be explained below, the piston rod with the pistons 12, 22 are moved by the combustion of fuel in the respective combustion chambers 14a, 14b, 24a, 24b. In addition, the first piston 12 and the second piston 22 and the working chambers 10, 20 and the cylinders 11, 21 are circular-cylindrical. The first piston 12 is also radially sealed against the wall of the first working chamber 10 so that highly expanding gases from the first combustion chamber substantially does not enter the second combustion chamber can and vice versa, the second piston 22 and the second working chamber 20 are carried out accordingly.

1 for the respective combustion chambers 14a, 14b, 24a, 24b, a fuel mixture supply channel 16a for the first combustion chamber 14a, a second fuel mixture supply channel 16b for the second combustion chamber 14b of the first cylinder 11, a third fuel mixture supply channel 26a for the first combustion chamber 24a of second cylinder 21 and a fourth fuel mixture supply passage 26b for the second combustion chamber 24b of the second cylinder 21. In another embodiment, for example, the second fuel mixture supply passage 16b and the third fuel mixture supply passage 26a may form a common passage. Radially opposite from the respective fuel mixture supply passages, exhaust discharge passages 18a, 18b, 28a, 28b are arranged, each of which the exhaust gas from the first combustion chamber 14a of the first cylinder 11, the second combustion chamber 14b of the first cylinder 11, the first combustion chamber 24a of the second cylinder 21, and of the second combustion chamber 24b of the second cylinder 21. In this case, the second Abgasabführkanal 18 b and the Abgasabführkanal 28 a can be configured as a common Abgasabführkanal. In Fig. 1, only a portion of the Abgasabführkanäle 18a, 18b, 28a, 28b can be seen in each case.

In one embodiment, the fuel mixture supply channels 16a, 16b, 26a, 26b are separated from the exhaust discharge channels 18a, 18b, 28a, 28b by the piston rod 30, as will be seen in detail in FIGS. 2a to 2d.

The piston rod 30 has axially adjacent to the piston 12, 22 recesses or fluid communication channels 32a, 32b, 32c, 32d, which extend in the longitudinal direction, in particular parallel to the longitudinal axis X, to a fluid connection between the respective fuel mixture supply channel and the respective combustion chamber 14a , 14b, 24a, 24b or between the respective combustion chamber 14a, 14b, 24a, 24b and the Abgasabführkanal 18a, 18b, 28a, 28b manufacture. In this case, the fluid connection is made only in each case in a certain rotation angle range of the piston rod. Further, there are rotation angle ranges in which the fluid communication passages 32a, 32b, 32c, 32d are sealed to both the respective fuel mixture supply passage 16a, 16b, 26a, 26b and the respective exhaust gas discharge passage 18a, 18b, 28a, 28b. This is the case for example for the connection channels 32a and 32d shown in the drawing, which is separated by a partition from the respective fuel mixture supply channels 16a, 16b, 26a, 26b and the Abgasabführkanälen 18a, 18b, 28a, 28b. In the embodiment shown in Fig. 1 is a Four-stroke internal combustion engine, in which the piston rod is set in a rotational movement, to ensure a fuel mixture supply and an exhaust gas removal. In this case, the piston rod 30 rotates once in four cycles once completely about its longitudinal axis X. Each combustion chamber of the internal combustion engine of Fig. 1 is in each case in a different clock.

This is explained in connection with FIGS. 2a to 2d, which show all four cycles from the third combustion chamber with the respective fluid connection channel 32c. In a first cycle, which is shown for example with respect to the first combustion chamber 24a of the second cylinder 21, the connecting channel 32c connects the third fuel mixture supply channel 26a with the first combustion chamber 24a of the second cylinder. During suction, the piston 22 of the second working chamber 20 is brought from a first axial extreme position or first dead center to a second axial extreme position or second dead center, simultaneously rotating the piston 22 and the piston rod by approximately 90 degrees (Figure 2a). Subsequently, the piston rod and the piston are moved from the second axial extreme position back to the first axial extreme position, wherein the fluid connection channel 32c is sealed both to the third fuel mixture supply channel 26a and to the Abgasabführkanal 28a (Figure 2b). In this case, the piston and the piston rod 30 rotates approximately by a further 90 ° degrees in the same direction (to the left in Fig. 2a to 2b). In this step, the fuel mixture located in the first combustion chamber 24 a of the second cylinder 21 is compressed. Subsequently, the fuel mixture is ignited, so that the piston 22 is again moved from its first axial extreme position to its second axial extreme position, so that the combustion chamber increases, with both the piston rod and the piston in turn perform a quarter turn (Fig. 2c). Once the engine has returned to its second axial extreme position, it moves back to the first axial extreme position by igniting a fuel-air mixture in another combustion chamber, the connecting passage 32c now communicating with the exhaust-gas discharge passage during this movement so that the combusted fuel mixture is pressed from the first combustion chamber 24a of the second cylinder in the third Abgasabführkanal (Fig. 2d). Then the process starts from the beginning.

The internal combustion engine in Fig. 1 has four combustion chambers, each located in a different clock of the four-stroke. Thus, the fuel mixture in the second combustion chamber 24 b of the second cylinder 21 is compressed, the compressed fuel mixture in first combustion chamber 14a of the first cylinder 11 just ignited and the burned fuel mixture in the second combustion chamber 14b of the first cylinder 11 just ejected.

The rotation allows in one embodiment of the free-piston engine as a four-stroke internal combustion engine. For this purpose, the piston rod 30, as already described above, at some points radially milled or tapered on one side to close the fresh air supply in one of the two dead centers corresponding to the first and second axial extreme positions. This milling meets in the housing on corresponding bore, which constitute an inlet, or a fuel mixture supply channel, and an outlet or Abgasabführkanal. The following conditions therefore result from the rotation:

1. Bottom dead center or first axial extreme position of the reciprocating movement of the piston rod: In this case, the milling or one of the fluid connection channels 32a, 32b, 32c, 32d overlaps on one side with the fresh gas opening in the housing and ends on the other side the combustion chamber.

2. Compaction and power stroke: The milling or the connecting channel is closed by the housing towards the end of the power stroke, the milling connects the combustion chamber with the outlet.

In a further embodiment, the milling or the connecting channel can be replaced by a bore extending diagonally through the piston rod, but then no fluids can be carried out through the piston rod or the piston in the longitudinal direction.

In one embodiment, the piston may be pierced or milled on one side to allow gas exchange in the case of a four stroke. In a further embodiment, the gas exchange can take place by means of slits through the cylinder wall, in particular in a four-stroke engine.

In order to set the pistons 12, 22 and the piston rod 30 at start and / or during a misfire in a rotational movement, a groove 40 with a bottom 42 and opposite walls 44a and 44b are arranged in the motor housing. In the groove 40 engage one or more radial projections 46 on the piston rod 30 a. In Fig. 3 is a developed view of the groove 40 is shown. The circumferential direction is shown horizontally and the axial direction is vertical. The developed in the circumferential direction Groove 40 roughly shows the various positions of the piston rod 30 and the pistons 12, 22 at one full revolution about their longitudinal axis X. Thus, the piston rod moves from a first axial extreme position (top dead center, TDC) to a second axial extreme position (lower Dead center, UT), and then back to the first axial extreme position.

In Fig. 3, two radial projections 46 are further shown, which serve to set in the event of a misfire or at start the piston rod 30 and the pistons 12, 22 in rotation. For this purpose, the radial projections 46 abut against one of the opposing walls 44a, 44b during an axial reciprocating movement, that is to say in FIG. 3 a vertical reciprocating movement. In normal operation, that is, unless there is no misfire or start of the free piston engine, the piston rod 30 is otherwise rotated with the pistons 12, 22, as will be explained below with reference to FIG. 4. However, the distance between the opposite walls 44a and 44b of the groove 40 is chosen so large that in normal operation, not at startup and not misfiring, the radial projection on the piston rod substantially does not contact the opposed walls 44a, 44b and Moving approximately on an idealized track approximately midway between the walls 44a, 44b. For example, the groove 40 may be milled into a sleeve 48 surrounding the piston rod, wherein the radial projection 46 is disposed laterally on the piston rod 30. In this case, a guide is mechanically performed at the start of the free-piston internal combustion engine.

In another embodiment, the guidance of the piston rod and the displacement of the same in a rotational movement about its longitudinal axis X can be electromagnetically. In this case, for example, permanent magnets are arranged in the piston rod and in the space surrounding the piston rod 30 corresponding windings for electrical control can be arranged. In a further embodiment, the leadership of the piston rod can be made inductively.

Due to the guide, the piston rod is rotated at each stroke. At the same time, the piston rod thus moves through firmly defined upper and lower dead centers, which can simplify the control considerably. Due to the kinetic moment of the rotation, the piston rod follows the lead even in the event of a misfire and the engine does not stop immediately. In principle, the internal combustion engine can be realized as a two-stroke engine or four-stroke engine, wherein, like each variant, it has its respective advantages and disadvantages. In a two-stroke engine, the construction can be made compact and the engine has a low specific power to weight ratio. On the other hand, the four-stroke internal combustion engine has the advantage that it causes a better gas exchange and thus a lower exhaust gas load and has a lower consumption. In the simplest case, the four bars are distributed over a 360 ° rotation of the piston rod. However, 8, 12, 16 bars, etc. per 360 degree rotation are conceivable.

4 shows an enlarged view of a piston according to the embodiment from FIG. 1. The piston 12 has a first combustion-chamber-side end face 122a facing the first combustion chamber 14a and a second combustion-chamber-side radial end face 122b facing the second combustion chamber 14b is facing. Furthermore, the piston 12 has a lateral surface 124 which is adapted to cooperate with the working space wall of a cylinder 11, so that gases from the first combustion chamber 14a can not enter the second combustion chamber 14b. The first and the second combustion chamber-side axial end faces 122a, 122b each have a first and a second radial reference plane 126a and 126b which is arranged orthogonal to the longitudinal axis X of the piston 12 or the piston rod 30. The radial reference planes 126a, 126b are respectively arranged to include the maximum elevation in the axial direction, respectively. The elevations are each viewed in the combustion chamber direction of the respective combustion chamber-side end face 122a, 122b. The combustion-chamber-side end faces each have sawtooth-like depressions 128a, 128b from the radial reference planes 126a, 126b, which extend radially rectilinearly or in a star shape from the longitudinal axis to the peripheral edges of the piston 12. In this case, the sawtooth depressions 128a, 128b are shaped such that the piston and the piston rod 30 are set in the event of a gas impingement, for example during the working stroke, during the ejection stroke, and / or during the compression stroke. As a result, the rotation is generated in accordance with an impinged turbine wheel. The recesses 128a, 128b are matched in one embodiment such that the piston 12 and the piston rod 30 are set in a uniform rotation about their longitudinal axis X. In particular, in the case of a free-piston four-stroke internal combustion engine with four combustion chambers, a uniform rotation about the longitudinal axis of the piston rod and the pistons 12, 22 can be generated. 5 shows a schematic axial cross section of a further embodiment of a free-piston internal combustion engine 100. FIG. 5 shows a combustion chamber. In this combustion chamber, a piston 102 moves, which has a plurality of recesses 104, which are shaped so as to enable the piston 102 upon impact of a gas in rotation about a piston rod 106. The combustion chamber is delimited by a guide sleeve or cylinder wall 108. In one embodiment, the guide sleeve 108 is stationary. The guide sleeve 108 and the outer circumference of the cylindrical piston 102 are adapted to one another in such a way that the combustion chamber shown in FIG. 5 is sealed against a further combustion chamber, which is also delimited by the piston 102. In a further embodiment, the guide sleeve can also be rotatably mounted. Then, the guide sleeve can be sealed against the motor housing in the axial direction. The guide sleeve has at least one inlet or outlet 110 for a fluid, for example exhaust gas or a fuel-air mixture. A control sleeve or mask 112 is arranged around the first guide sleeve 108, in particular concentrically, wherein the control sleeve and the guide sleeve are shaped such that substantially no fluid can flow between the two sleeve walls, in particular in the axial direction. The control sleeve 112 has at least one control opening 114 for the fluid, for example exhaust gas or a fuel-air mixture. The control sleeve can be stationary in one embodiment, when the guide sleeve is rotatably mounted, or in another embodiment, the control sleeve can be rotatably mounted about its own axis and the guide sleeve 108 stationary. In a further embodiment, both the guide sleeve and the control sleeve can be rotatable.

In this case, the guide sleeve and / or the control sleeve is rotated about its longitudinal axes, that at the first and at the fourth stroke of a four-stroke engine, the two openings 110, 114 at least partially overlap, so that a suction of a fuel-air mixture or an ejection of exhaust gas can be carried out. In further embodiments, the guide sleeve and / or the control sleeve more than each have only one opening per combustion chamber, for example, have two or more openings per combustion chamber, in particular the speed with which rotates the respective rotatable sleeve, the clock numbers and the speed adapted to the free-piston engine. In a further embodiment, both the guide sleeve 108 and the control sleeve 112 can be rotatably mounted about its longitudinal axis. In one embodiment, the guide sleeve and / or the control sleeve can be driven by the piston or all pistons of the free-piston internal combustion engine. This can be done via a transmission in one embodiment. In another embodiment, for example, the piston 102 may have a driving groove or a projection which engages in a corresponding projection or groove of the guide sleeve 108. For example, the same openings in the exhaust gas rinsing and / or control sleeve and a fuel-air mixture may be used.

FIGS. 6a and 6b each show, in a developed view, a guide sleeve 108 (FIG. 6a) and a control sleeve 112 (FIG. 6b). In each case, an opening 110a, 110b, 110c, 11 Od for each one of the four combustion chambers of the free-piston engine in the respective firing order on the guide sleeve 108 are arranged. In Fig. 6b, the control sleeve 112 is shown with the respective control ports 114a, 114b, 114c, 114d, wherein in each case a control port 114a, 114b, 114c, 114d, each with an opening 110a, 110b, 110c, HOd in the guide sleeve 108 cooperates. For example, in one embodiment, the openings of the guide sleeve may all be arranged at the same angle with respect to the axis X and the openings of the control sleeve for each combustion chamber have a different angle and vice versa. For example, the openings of the guide sleeve may have a regular angular distance. About the angular distance of the time and / or the size and / or shape of the openings and the amount of exhaust gas or the fuel-air mixture can be controlled, which flow in or out of a combustion chamber.

In the case of a stationary control sleeve, for example, the exhaust gas or supply channels can be directly fixedly connected to the guide openings 114a, 114b, 114c, 114d. In one embodiment, the guide sleeve and / or the control sleeve can be axially displaceable, so that above the passage cross-section for the exhaust gas and / or the fuel-air mixture can be varied. In a further embodiment, the openings may not have rectangular but curved edges, so that, for example in combination with an axial displacement of the control sleeve and / or the guide sleeve, the passage cross section can be controlled.

7 shows a side cross sectional cross-sectional view of another embodiment of a free piston internal combustion engine 200. The free piston internal combustion engine has a first portion 202 and a second portion 204. The first section 202 comprises a first working chamber 210 and the second section 204 comprises a second working chamber 220, wherein the working chambers are each divided by a piston 212, 222 into a first combustion chamber 214a, 224a and a second combustion chamber 214b, 224b. The first section 202 has a first piston rod 216 to which the first piston 212 is rotationally fixed is fixed and the second portion 204 has a second piston rod 226, on which the second piston 222 is rotatably mounted. During operation, the pistons move synchronously back and forth. For example, the first piston rod may be connected to the second piston rod to transmit movement of the first piston rod in the axial direction to the second piston rod and vice versa.

In one embodiment, the rotational movement is transmitted via a transmission 230, which transmits a rotational movement of the first piston rod 216 to a rotational movement of the second piston rod 226 or a rotational movement from the second piston rod to a rotational movement of the first piston rod 216. Consequently, the free-piston engine 200 can be compactly arranged. For example, the transmission 230 has three gears 232, 234 and 236, with the first gear 232 attached to the first piston rod and the third gear 236 attached to the second piston rod and the second gear 234 transmitting the power from the first gear 232 to the third Gear 236 accomplished. In other embodiments, others may be used

Torque transmission mechanisms are used, for example, a belt, a chain, or the like.

In Fig. 8 is a side view of the transmission to see, with the first gear 232, the second gear 234 and the third gear 236. In another embodiment, the free-piston internal combustion engine on only two gears, each on the first piston rod 216 and the second piston rod 226 are attached. Then the first piston rod and the second piston rod run in opposite directions.

In the embodiments presented above, all the generic advantages of a free-piston engine are retained. Existing and established technologies, such as direct injection or turbocharger can be used in other embodiments without special design effort. The drive of ancillaries, such as an alternator, is also easily possible.

The engine may preferably be used in a (full) hybrid system. For this purpose, a linear generator can be fastened to the piston rod or arranged, for example, between the pistons 12, 22 according to the embodiment from FIG. The power thus generated can then drive electric motors of a motor vehicle. In another embodiment, the rotation can also be used by means of a simple coupling to a drive.

In these cases, the following combinations are conceivable: in the automotive sector, the drive of the wheels in the case of a hybrid can be accomplished by electric motors. The same applies to locomotives. Likewise, in ships, the propeller can be propelled by electric motors, as is already customary in so-called "pods." Such a hybrid drive can also be used in the field of aircraft, with electric motors driving a propeller.

In the case of a mechanical drive, where the rotation of the piston rod 30 is used directly, for example, in a motor vehicle, the piston rod is coupled directly to a transmission. In ships, for example, the piston rod could be coupled to a shaft of the screw. In the example of aircraft, the piston rod could be coupled to a propeller.

The features of the invention disclosed in the foregoing description, in the claims and in the drawings may be essential both individually and in any combination for the realization of the invention in its various embodiments.

Claims

claims

A piston (12, 22, 102, 212, 222) for a free piston internal combustion engine (1, 100, 200) having a first combustion chamber side end face (122a) and a cylinder axis (X) substantially perpendicular to the first combustion chamber end face the first combustion-chamber-side end face is shaped in such a way that the piston can be set into rotation in a first direction of rotation about the cylinder axis by a gas impinging on the first combustion chamber-side end face.

2. Piston according to claim 1, wherein

the piston has a second combustion chamber-side end face (122b), which is disposed axially opposite the first combustion chamber-side end face and is shaped such that the piston can be displaced into a rotation about the cylinder axis by a gas impinging on the combustion chamber-side end face is, in particular in the first direction of rotation.

3. Piston according to claim 1 or 2, wherein

the first and the second combustion chamber-side end surface are mirror-symmetrical to a radial plane perpendicular to the cylinder axis in the piston.

4. Piston according to one of the preceding claims, wherein

the at least one combustion chamber-side end face has a radial reference plane (126a, 126b) which is arranged in the direction of the combustion chamber at a maximum elevation, the end face having at least one recess (128a, 128b) with respect to the end face, the depressions being shaped in particular like a sawtooth are.

5. Piston according to claim 4, wherein

the recesses extend in the radial direction, in particular in a star shape.

6. Piston arrangement with at least one first piston according to one of claims 1 to 5 and a first piston rod (30, 106, 216), wherein the at least one first piston (12, 212) is attached to the first piston rod, wherein in particular the first

Piston rod extends in the axial direction on the cylinder axis of the first piston.

7. Piston assembly according to claim 6, wherein

the piston assembly comprises a second piston rod (226) to which at least a second piston (222) is attached, wherein in particular the second piston rod extends in the axial direction on the cylinder axis of the at least second piston, Preferably, the first and second piston rod are arranged parallel side by side.

8. Piston assembly according to claim 6 or 7, wherein

at least a second piston (22) according to any one of claims 1 to 5 is attached to the first piston rod (30) and / or on the second piston rod (226), wherein in particular the first and second piston rod in the axial direction on the cylinder axis of the second Piston extends, wherein preferably at least a first and the at least one second piston are spaced from each other to the first and second piston rod attached.

9. Piston assembly according to claim 7 or 8, wherein

the first piston rod and the second piston rod are coupled such that the first piston rod is movable together with the second piston rod in the axial direction thereof.

10. Piston arrangement according to one of claims 7 to 9, with a

A rotary coupling device for transmitting a rotation of the first piston rod about its own axis to a rotation of the second piston rod about its own axis, wherein in particular the rotary coupling device is a gear, a belt and / or a chain.

11. Piston arrangement according to one of claims 6 to 10, wherein

the first and / or second piston rod having at least one fluid channel (32a, 32b, 32c, 32d) for a fuel-air mixture and / or exhaust, wherein in particular the first and / or second piston rod (30, 216, 216) for each The combustion chamber-side end face of a at least one first and / or at least one second piston fastened to the respective piston rod has at least one fluid channel for a fuel-air mixture and / or exhaust gas.

12. Piston assembly according to claim 11, wherein

wherein the at least one fluid channel is arranged such that it at least temporarily a fluid connection between a fuel-air mixture supply channel and adjacent to the combustion chamber surface combustion chamber of the at least one first and / or second piston and / or between an exhaust passage and an the combustion-chamber-side surface produces adjacent combustion chamber of the at least one first and / or second piston.

13. Piston assembly according to claim 11, wherein

the at least one fluid channel extends in the axial direction, in particular in a straight line.

14. Piston assembly according to one of claims 11 to 13, wherein

the at least one fluid channel is a groove.

15. Internal combustion engine (1, 100, 200) with a motor housing in the axial direction back and forth movable piston assembly according to one of claims 6 to 12, wherein each combustion chamber-side end face of the at least one first piston and / or at least one second piston a combustion chamber ( 14a, 14b, 24a, 24b, 214a, 214b, 224a, 224b) and limits it in an axial direction.

16. Internal combustion engine according to claim 15, wherein

the at least one first and / or at least one second piston is or are respectively arranged in a working space (10, 20, 210, 220), and wherein the

Internal combustion engine having at least one Führnngshülse, wherein at least one working space in the radial direction by the at least one Führnngshülse (108) is limited, at which the respective piston moves along, wherein the at least one

Guide sleeve at least one exhaust and / or fuel-air mixture supply port (110) for at least one combustion chamber, in particular for each

Combustion chamber, has.

17. Internal combustion engine according to claim 16, wherein

at least one control sleeve (112) is arranged in the radial direction about the at least one guide sleeve (108), the at least one control sleeve having at least one exhaust gas and / or fuel / air mixture feed opening (114) for at least one combustion chamber, in particular for each combustion chamber , wherein the

Internal combustion engine is set up such that for at least one combustion chamber, the at least one exhaust and / or fuel-air mixture supply port of the control sleeve and the at least one exhaust and / or fuel-air mixture supply port of the guide sleeve can be different.

18. Internal combustion engine according to claim 16 or 17, wherein

the at least one guide sleeve and / or the at least one control sleeve are rotatable about the longitudinal axis.

19. Internal combustion engine according to any one of claims 16 to 18, wherein

the at least one exhaust gas and / or fuel-air mixture feed opening of the at least one guide sleeve and the at least one control sleeve are arranged such that at least two combustion chambers are in different cycles at the same time during operation.

20. Internal combustion engine according to claim 18 or 19, wherein

the at least one guide sleeve and / or the at least one control sleeve is / are coupled to the first and / or the second piston rod (30, 216, 226) in such a way as to rotate the first piston rod and / or the second piston rod about their own axis to transfer to a rotation at least one guide sleeve and / or the at least one control sleeve about its own axis.

21. Internal combustion engine according to any one of claims 16 to 20, wherein

the at least one guide sleeve and / or the at least one control sleeve in

Axial direction are movable.

22. Internal combustion engine according to one of claims 16 to 21, comprising

at least one exhaust duct (18a, 18b, 28a, 28b) and at least one fuel-air mixture supply channel (16a, 16b, 26a, 26b) for each combustion chamber, wherein in particular the at least one exhaust duct and / or the at least one fuel mixture Supply channel is limited by the piston rod or are.

23. Internal combustion engine according to claim 22, wherein

the at least one fluid channel, the motor housing, the at least one exhaust gas channel, the at least one fuel-air mixture supply channel, at least one guide sleeve and / or the at least one control sleeve are designed such that the at least one fluid channel and / or the at least one exhaust gas - And / or fuel-air mixture supply port during operation of the internal combustion engine temporarily establishes a first fluid connection between the exhaust passage and the combustion chamber and temporarily a second fluid connection between the fuel-air mixture supply passage and the combustion chamber.

24. Internal combustion engine according to claim 23, wherein

the internal combustion engine is set up such that the first and second

Fluid connection can be produced simultaneously or in time.

25. Internal combustion engine according to claim 23 or 24, wherein

the same fluid passage and / or the same exhaust and / or fuel-air mixture supply port produces the first fluid connection and the second fluid connection.

26. An internal combustion engine according to any one of claims 23 to 25, wherein

the first fluid connection is made at at least a first rotation angle range of rotation of the piston assembly and the second fluid connection at at least a second rotation angle range of rotation of the piston assembly, wherein the at least one first rotation angle range and the at least one second rotation angle range

Rotation angle range do not overlap.

27. Internal combustion engine according to any one of claims 15 to 26, wherein

the internal combustion engine is a four-stroke internal combustion engine.

28. Internal combustion engine according to claim 27, wherein

the internal combustion engine comprises at least four combustion chambers and at least two pistons, wherein the fluid channels, the at least one guide sleeve and / or the at least one control sleeve, are designed such that at the same time each pulse occurs at least once during operation.

29. Internal combustion engine according to any one of claims 15 to 28, wherein

at least one first guide element on the first and / or second piston rod and / or the piston skirt surface and at least one second guide element is arranged on the motor housing, wherein the first guide element cooperates with the second guide element such that the piston assembly in an axial movement in a rotational movement displaceable is.

30. Internal combustion engine according to claim 29, wherein

the cooperating guide elements are a groove and at least one projection, wherein in particular the at least one projection on the piston rod and / or piston skirt surface is arranged.

31. Internal combustion engine according to claim 30, wherein

the at least one groove has two side walls whose spacing from one another defines a width of the groove, the groove being wider than the projection, in particular at least twice as wide as the projection, so that the projection can be guided through the groove without contacting the side walls.

32. Internal combustion engine according to any one of claims 29 to 31, wherein

the cooperating guide elements are coils and / or magnets of an electric motor.

33. Internal combustion engine according to any one of claims 29 to 32, wherein

the cooperating guide elements are designed such that in operation a complete rotation of the piston assembly is achieved after four cycles or a multiple of four cycles.

34. Internal combustion engine according to any one of claims 15 to 33, wherein

the at least one combustion chamber-side end face of the at least one piston is designed and cooperates in such a way that, in proper operation, a complete rotation of the piston assembly is achieved after four cycles or a multiple of four cycles.