EP0224142A2 - Free piston internal-combustion engine - Google Patents

Abstract

The working piston (4) of the cylinder (1) is firmly connected via a piston rod (7) to the piston (5) of a hydraulic pump (2). This piston (5) is in turn firmly connected via a piston rod (8) to the compressor piston (6) of the charge-air pump (3). A charge-air cell (12) is formed between the cylinder wall (23) and an outer shell (11) of the cylinder (1). The charge air delivered by the charge-air pump (3) enters the charge-air cell (12) in order to enter the respective combustion chambers (9, 10) from there via inlet valves (20, 21). The fluid delivered by the hydraulic pump (2) flows into an air receiver (60). From the latter, the fluid flows further into a hydraulic turbine (66), the useful energy being delivered via the turbine shaft (67). Since the fluid is incompressible, the transmission of force from the hydraulic piston pump (2) to the turbine (66) is effected with only very small losses. This ensures better thermal efficiency of the internal-combustion engine. The internal-combustion engine is of very simple and compact construction. Only one cylinder (1) is required to produce a virtually uniform output at the turbine shaft (67). <IMAGE>

Description

The present invention relates to a free-piston internal combustion engine, with at least one cylinder with a double-acting working piston guided longitudinally displaceably therein, and with a charge air pump.

Free-piston internal combustion engines are known and are preferably used for electrical energy generation.

It is an object of the invention to show a free-piston internal combustion engine which, compared to known machines, has an increased thermal efficiency, is of simpler and more compact design and is inexpensive to produce.

The invention, as characterized in the claims, solves the problem of creating a free-piston internal combustion engine in which the cylinder for forming a charge air reservoir has an outer jacket, the charge air pump has a double-acting compressor piston which is connected to the working piston via a piston rod arrangement is which charge air pump is connected to the charge air reservoir via a charge air line.

The advantages achieved by the invention are essentially that a very high thermal efficiency is achieved, whereby the construction is characterized by a great simplicity.

• Fig. 1 schematisch eine Ausführung der erfindungsgemässen Freikolben-Brennkraftmaschine;
• Fig. 2 eine Ausführungsvariante der.in der Fig. 1 gezeigten Freikolben-Brennkraftmaschine;
• Fig. 3 schematisch einen Schnitt durch den Arbeitszylinder der Freikolben-Brennkraftmaschine;
• Fig. 4 eine schematische Darstellung der Auslassschlitze, und
• Fig. 5 schaubildlich einen Abschnitt des Zylinders in ausgeschnittener Darstellung.

In the following, the invention will be explained in more detail with reference to the drawings illustrating the ways of implementation. It shows:

• 1 schematically shows an embodiment of the free-piston internal combustion engine according to the invention;
• FIG. 2 shows an embodiment variant of the free-piston internal combustion engine shown in FIG. 1;
• 3 schematically shows a section through the working cylinder of the free-piston internal combustion engine;
• Fig. 4 is a schematic representation of the outlet slots, and
• Fig. 5 shows a section of the cylinder in a cutaway view.

1 generally shows a cylinder 1, a liquid piston pump 2 and a charge air pump 3. The reference number 60 shows a wind boiler, and a turbine is indicated by the reference number 66. The preferred embodiment of the free-piston internal combustion engine contains only one cylinder 1, but several cylinders 1 operating in parallel are also conceivable for larger outputs, for example. The cylinder 1 has a cylinder wall 23 and an outer jacket 11. In between, a jacket space serving as charge air reservoir 12 is formed. In this charge air reservoir 12, the cylinder wall 23 with the outer casing 11 connecting cooling fins 53 are arranged. The preferred embodiment of these cooling fins 53 is shown in FIGS. 3 and 5. These cooling fins 53 are annular disks in which recesses 93 are present. The embodiment of these cooling fins 53 shown is the preferred embodiment, and other configurations are also conceivable. The essential thing is that these cooling fins 53 the cylinders Connect wall 23 to the outer jacket 11. The cylinder 1 is provided with outlet slots 57. The arrangement of the same is shown schematically in FIG. 4. The outlet slots 57 run parallel to one another and parallel to the cylinder axis. They are arranged in a pattern, as shown in FIG. 4. The outlet slots 57 have different longitudinal dimensions. The middle outlet slot 57 has the greatest longitudinal expansion. The delivery slots located on both sides of the middle outlet slot 57 are progressively shorter, so that the two outermost outlet slots of the pattern have the smallest longitudinal extent.

The cylinder 1 is guided in a longitudinally displaceable manner. double-acting piston 4 arranged. Numeral 9 denotes the first combustion chamber, and numeral 10 denotes the second combustion chamber. The first combustion chamber 9 is connected via an inlet valve 20 designed as a non-return valve and the second combustion chamber 10 via a further inlet valve 21 designed as a non-return valve to the jacket space serving as charge air reservoir 12.

The axial extent of the piston 4 arranged in the cylinder 1 is obviously longer than the longitudinal extent of the longest of the outlet slots 57. The axial length of the working piston 4 is, taking into account the axial length of the cylinder 1, the minimum and maximum piston stroke, the desired compression in the combustion chambers 9 and 10 and obviously the dimensions of these combustion chambers. The working piston 4 is sealed at both ends by piston rings 18, 19 against the cylinder wall 23. Although only one piston ring 18, 19 schematically is drawn, it is obvious that a set of piston rings of known arrangement may be present. In the combustion chamber 9 there is a catalytic converter, generally designated 15, and in the combustion chamber 10, a catalytic converter generally designated 17. These catalyst devices 15, 17 are lattice-shaped and consist of "cermet" or another, heat-resistant and chemically inert substance on which a substance acting as the actual catalyst, for example platinum, is applied. In the embodiment shown, the cylinder end sections and the end faces of the piston are curved, but can also have other shapes.

The working piston 4 is firmly connected to a piston rod 7. This runs in a sealed manner through the cylinder wall 23 and the jacket 11 and is firmly connected to the piston 5 and the liquid pump 2.

This liquid pump 2 has two inlet valves 24, 26 and two outlet valves 25, 27. The piston 5 of the liquid pump is thus also a double-acting piston. The piston 5 of the liquid pump 2 is fixedly connected to the compressor piston 6 of the charge air pump 3 via a further piston rod 8. Obviously, the passage points of the piston rod 8 are sealed here by the walls of the liquid piston stem 2 and the charge air pump 3. An air filter 32 is connected upstream of the charge air pump 3. The charge air pump 3 has two intake valves 29, 30 and two exhaust valves 28, 31.

The cross-sectional area, ie working surface of the compressor piston 6 of the charge air pump 3, is larger than that of the working piston 4 or, in other words, the compressor piston 6 has one larger diameter than, the working piston 4.

The stroke of the two pistons 4, 6 is obviously the same. In a preferred embodiment, in which a charge of approximately 5 × 10 ⁵ Pa is present in the charge air reservoir 12 of the cylinder 1 (which pressure is correspondingly higher in operation due to the correspondingly high temperature), the cylinder wall 23 has an inner diameter of 4 cm and the outer jacket 11 has an inner diameter of approximately 5.7 cm, and accordingly the diameter of the compressor piston 6 of the charge air pump 3 is approximately 8 cm. The compressor piston 6 thus has a larger diameter than the working piston 4.

The liquid piston pump 2 conveys a liquid in a closed circuit, for example water with possible additives for corrosion protection, anti-freeze protection, etc. The liquid conveyed by the piston 5 of the liquid pump 2 flows through the outlet valves 25, 27 into an outlet line 70. This outlet line 70 has three connected to small pumps. The reference number 39 designates the fuel injection pump and the reference numbers 44, 47 designate the lubricant pumps.

The fuel injection pump 39 has a piston 40 which is biased by a spring 41. The lubricant pump 44 has a piston 49 biased by a spring 50 and the lubricant pump 47 has a piston 51 biased by a spring 52. The end faces of the three pistons 40, 49, 51 are exposed against the outlet line 70. Your working surfaces are thus subjected to the pressure of the liquid delivered by the liquid piston pump 2. With each stroke of the piston 5 of the liquid piston pump 2, the three pistons 40, 49, 51 become counter to the force their respective springs 41,50,52 shifted. When the piston 5 reaches a dead center and the pressure of the liquid delivered by the liquid piston pump 2 drops, the springs 41, 50, 52 move their respective pistons 40, 49, 51 back to their starting position. As a result, the fuel injection pump 39 and the lubricant pumps 44, 47 are driven by the liquid piston pump 2. At a location in FIG. 1 after the fuel injection pump 39, a changeover valve 88 is arranged in the outlet line 70, the purpose of which is explained further below. The outlet line 70 runs after the lubricant pumps 44, 47 to a wind boiler 60. The air boiler 60 contains air under pressure or another gas under pressure. The line leading out of the wind chamber 60 is fed to a throttle valve 64, the position of which is controlled by a pressure sensor 63 arranged in the wind chamber 60. The liquid then flows from the throttle valve 64 into a liquid turbine 66. This turbine 66 can be a Pelton turbine, a vane wheel turbine or a Kaplan turbine. The turbine 66 is connected to the turbine shaft 67. Consequently, the linear stroke movement of the piston of the free-piston internal combustion engine is converted into a rotary movement of the turbine shaft during operation. A power generator can now be connected to this turbine shaft 67, for example. Finally, a return line 68 connects to the turbine 66, through which the liquid flows back through the changeover valve 88 to the liquid piston pump 2, in order to flow back into the respective working chambers through the inlet valves 24, 26. A closed liquid circuit is therefore present, on the basis of which the piston movement of the liquid piston pump 2 basically rotates the turbine 66 is implemented.

The charge air pump 3 draws in the air through the air filter 32, which air enters the working chambers through the inlet valves 29, 30. The air is then conveyed through the movement of the compressor piston 6 through the two outlet valves 28, 31 into the charge air line 16. This charge air line 16 is the main charge air inlet valve 22 designed as a check valve to the charge air reservoir 12, i. the jacket space of the cylinder 1, supplied. The air compressed and delivered by the compressor piston 6 thus enters the charge air reservoir 12. This is equipped with a safety valve 14, a pressure relief valve, which relieves the charge air accumulator if the charge air pressure is too high.

The exhaust gases flow through the outlet slots 57, through the oil pan 56 into the exhaust pipe 58, and through the exhaust pipe 62 into the open.

The lubricant pump 47 sucks the lubricant from the oil pan and conveys it through the lubricant filter 54, that is, the oil filter to the lubricant storage container 55. The lubricant pump 44 in turn sucks the lubricant from the lubricant storage container 55 and conveys it through line 71 to the various locations to be lubricated Free piston internal combustion engine.

The fuel injection pump 39 sucks the fuel through the fuel supply pipe 48 from the fuel storage container, not shown. The fuel injection pump 39 is equipped with a safety valve 74, through which fuel flows back to the fuel supply pipe 48 or to the fuel storage tank if the fuel injection pump 39 has an excessively high delivery pressure.

A throttle valve 73 is arranged at the outlet of the fuel injection pump 39. This throttle valve is controlled either by manual actuation or, for fully automatic operation, by a pressure sensor 72 which senses the pressure prevailing in the cylinder chamber of the fuel injection pump 39. The fuel supply line running from the fuel throttle valve 73 branches out and extends to the fuel injection valves 75, 76. These injection valves 75, 76 are controlled by the inlet valve 21, which connects the jacket space 12, i.e. the charge air reservoir, to the second combustion chamber 10. If the inlet valve 21 is open, the injection valve 76 is open and the fuel is injected into the first combustion chamber 9 through the check valve 77. When the valve 21 is closed, the injector 76 is also closed and the valve 75 is open, and the fuel is injected into the second combustion chamber 10 through the check valve. In this embodiment, the internal combustion engine has an electrical system for ignition, the ignition being effected via glow plugs 79, 80.

The starting cylinder 36 is arranged next to the fuel injection pump 39. The starting piston 37 arranged in the starting cylinder 36 is rigidly connected to the piston 40 of the fuel injection pump 39 via a piston rod 38. The end face of the starting piston 37 is larger than the end face of the piston 40 of the fuel injection pump 39. The starting cylinder 36 is connected to the charge air reservoir 12 of the cylinder 1 via a pipe 33 in which a shutoff valve 34 is arranged. The starting cylinder 36 also has a ventilation valve 35. The piston rod 38 is sealed against the bottom of the starting cylinder 36.

Two spring-loaded control arms 86, 87 protrude through the wall of the starting cylinder 36 at a point in the cylinder space which corresponds to approximately 60% of the stroke distance of the starting piston 37 when it moves from left to right according to FIG. These control arms 86, 87 are pivotally supported by springs 43, the pivot points 42 being located outside the starting cylinder 36. These control arms 86, 87 control the valves 34, 35, as will be described in more detail below. The control arms 86, 87 also protrude through slots 46 in the wall of the starting cylinder 36 in the interior thereof. It can thus be seen that when the starting piston 37 moves to the right in FIG. 1, it comes to bear against the control arms 86, 87 and thus causes the same to be deflected. If the starting piston 37 moves to the left again, the control arms 86, 87 are pivoted back into their rest position by the springs 43. The outlet line 70 is fed to a changeover valve 88 at a point downstream of the fuel injection pump 39. In the operating position shown, the liquid coming from the fuel injection pump 39 flows through the changeover valve 88 in order to continue to flow against the lubricant pumps 44, 47 and from there ultimately to the turbine 66. To start up, the changeover valve 88 is moved into a position in which the liquid after the fuel injection pump 39 can be returned to the liquid piston pump 2, that is to say the lubricant pumps 44, 47 and in particular the turbine 66 are not driven by the liquid.

It should be noted that the described embodiment of the free-piston internal combustion engine emits its usable energy via the turbine shaft 67.

In another embodiment, not shown, the wind boiler and turbine 66 are omitted. It is thus possible to use the internal combustion engine as a pump drive with the liquid pump 2, the piston 5 of which is firmly connected to the piston 4, so that liquid or even gas can be conveyed by the pump 2, for example.

The start-up and operation of the embodiment shown will now be explained below. To start up, it is necessary that compressed air is present in the jacket space, that is to say charge air reservoir 12. It was mentioned earlier that in the cold state, a pressure of approximately 4 × 10 ⁵ Pa must be present in the charge air reservoir 12. If the internal combustion engine is put into operation for the first time or work has been carried out on the cylinder 1 which requires it to be vented, so that ambient pressure prevails in the air charge accumulator 12, compressed air is initially introduced into the charge air accumulator 12, so that the air therein is under one Starting necessary pressure is available.

If the internal combustion engine has been brought to a standstill by cutting off the fuel supply, that is to say has only been out of operation for a relatively short time, pressurized charge air is stored in the charge air reservoir 12. Immediately after the internal combustion engine has been switched off after full operation, the charge air present in the charge air reservoir 12 is additionally heated and is therefore at a higher pressure. To start the internal combustion engine, however, the pressure mentioned above is sufficient when the charge air is cold. In the parked state, the working piston 4 is located approximately in the middle of the cylinder.

It is assumed that when the internal combustion engine was switched off beforehand, the last fuel injection into the first combustion chamber 9 took place. The combustion in the combustion chamber 9 caused the last working stroke of the working piston 4 caused the inlet valve 21 to close because the working piston 4 obviously moved in the direction of the second combustion chamber 10. The charge air present in the combustion chamber 10 has obviously been compressed. However, since no more fuel has been injected, no combustion has taken place in the combustion chamber 10.

The aforementioned last working movement of the working piston 4 in the drawing upwards released the outlet slots 57. The gases present in the combustion chamber 9 could thus flow out through the slots 57 and the exhaust pipe 58, with the result that a pressure drop in the combustion chamber 9 took place. Due to this pressure drop, the inlet valve 20 has opened briefly in order to allow fresh charge air to flow from the charge air reservoir 12 into the combustion chamber 9. However, the pressure of the charge air present in the combustion chamber 9 obviously cannot exceed that of the charge air present in the charge air accumulator 12.

However, since the pressure of the charge air present in the upper combustion chamber 10 is somewhat higher than the pressure existing in the combustion chamber 9 due to the previous upward movement of the piston 4, the working piston 4 is pressed down a small distance in the direction of the combustion chamber 9 and thus are the Outlet slots 57 have been closed again and the charge air pressure in the combustion chamber 9 has been increased somewhat. This also closes the inlet valve 21, so that the working piston 4, as mentioned previously, comes to a standstill approximately in the middle of the cylinder 1, at which position of the working piston 4 the charge air pressures in the first combustion chamber 9 and the second combustion chamber 10 are balanced. _However , since the compressor piston 6 of the charge air pump 3 and the piston 5 of the liquid pump 2 are rigidly connected to the working piston 4 via the piston rod arrangement 7, 8, these two pumps generate a resistance to the movement of the working piston 4, so that it is somewhat in the figure comes to stand higher, ie comes to rest a little more in the direction of the second combustion chamber 10.

To start up, the changeover valve 88 has therefore been switched to the position in which the circulating liquid is returned directly from the fuel injection pump 39 to the liquid pump 5. The fuel throttle valve 73, which is arranged at the outlet of the fuel injection pump 39, is then controlled into its open position. The piston 40 of the fuel injection pump 39 is under the action of the spring 41 biasing it in an upper dead center position, i.e. 1 in the left position, the spring 41 is now in the fully expanded state. The vent valve 35 of the starting cylinder 36, which was previously open and during continuous operation of the internal combustion engine, is now closed and at the same time the shut-off valve 34 connecting the interior of the starting cylinder 36 via the pipe 33 to the charge air reservoir 12 is opened. Thus, pressurized charge air flows from the charge air reservoir 12 to the starting piston 37 of the starting cylinder 36 and urges it to the right in the figure. After a stroke of 60%, the starting piston 37 comes into contact with the two control arms 86, 87. These control arms 86, 87 thus pivot out and cause the shut-off valve 34 to be closed and the vent valve 35 to be opened at the same time.

Since the starting piston 37 via the piston rod 38 is connected to the piston 40 of the fuel injection pump 39, the fuel is first delivered.

Returning now to the movement of the control arms 86, 87, the opening of the ventilation valve has the effect that the starting piston 37 is relieved and, due to the spring 41 of the fuel injection pump 39, is returned to its left position in the FIG. The springs 43 of the control arms 86, 87 lead them back to their starting point, so that the shut-off valve 34 is opened again and the vent valve 35 is closed and the next compressed air can flow from the charge air reservoir 12 to the starting piston 7. The starting cylinder 36 and the starting piston 37 are dimensioned such that the air pressure present in the charge air reservoir 12 is sufficient to actuate the fuel injection pump 39 several times in continuous operation up to a stroke of 60% of the stroke.

It should also be mentioned that the cylinder interior of the starting cylinder 36 below the starting piston 37, that is to say in FIG. 1 the cylinder interior lying to the right of the starting piston 37, is connected to the surroundings via the slots 46, through which the control arms 86, 87 protrude. This means that no air cushion can arise under the starting piston 37 during the working stroke of the starting piston 37.

If the shut-off valve 34 has been opened, the starting piston 37 and thus the piston 40 of the fuel injection pump 39 have been moved to the right, fuel is injected into the combustion chamber 10 by the fuel injection pump 39. Simultaneously with the opening of the shut-off valve 34, which causes the fuel to be injected, the circuit to the glow plugs 79 and 80 is closed. So it is inserted into the second combustion chamber 10 injection fuel ignited and thus the piston 4 moved against the first combustion chamber 9. The charge air present in this combustion chamber 9 is thus compressed.

The piston 5 of the liquid pump 2 is obviously also moved by the movement of the working piston 4 and the working liquid is returned directly to the liquid piston pump 2 through the changeover valve 88. Since the working liquid is fundamentally only conveyed from one side of the piston 5 to the opposite side and does not perform any useful work, this circulating movement of the liquid exerts very little resistance on the working piston 4.

Due to the first stroke of the working piston 4, the compressor piston 6 of the charge air pump 3 is also displaced and charge air is conveyed into the charge air reservoir 12. However, only a small amount, a small volume of charge air, is conveyed into the charge air reservoir 12 because the working piston 4 has only moved a small distance. When the working piston 4 has carried out the first lifting movement, the starting cylinder 36 is operated again in the manner mentioned above. However, since the working piston 4 has moved against the combustion chamber 9, the outlet slots 57 of the cylinder 1 are opened and thus the pressure in the combustion chamber 10 drops. The small volume of the charge air conveyed by the charge air pump 3 causes the pressure in the charge air reservoir 12 to increase increased again. The working piston 4 moves downward, the inlet valve 21 is opened and a further quantity of fuel is injected into the combustion chamber 9 and ignited there. The working piston 4 and thus also the compressor piston 6 move and thus a further volume flows Men charge air in the charge air reservoir 12, and because the pressure in the charge air reservoir 12 has already become higher than the outlet pressure, the starting cylinder 36 already works better, the starting piston 37 is moved more strongly against the force of the spring 41. This means that a larger amount of fuel is injected from work cycle to work cycle. The temperature in cylinder 1 increases, the engine becomes hot and the pressure of the charge air in charge air reservoir 12 will also grow faster and faster. The work cycles, ie ignitions of the amount of fuel injected, follow one another at increasingly shorter time intervals and the internal combustion engine has now started.

The changeover valve 88 can now be switched over to continuous operation so that the working fluid flows through the turbine 66, the shutoff valve 34 also being closed and the venting valve 35 being opened, which two valves remain in this state during the continuous operation. Now the internal combustion engine runs regularly and the supply of electrical current to the glow plugs 79, 80 is interrupted. By controlling the throttle valve 73, the fuel supply and thus the working speed of the internal combustion engine are controlled.

The flow of fresh air and combustion gas on the flow side during continuous operation of the internal combustion engine will now be described with reference to FIG. 1. The double-acting compressor piston 6 of the charge air pump 3 sucks fresh air through the air filter 32 and the inlet valves 29, 30 and conveys this through the outlet valves 28, 31 to the charge air line 16, which runs to the inlet valve 22, through which inlet valve 22 the charge air into the charge air reservoir 12 flows in. The delivery rate of the charge air pump 3, which in particular from the working surface of the compressor piston 6 depends, is dimensioned depending on the design of the internal combustion engine for diesel or gasoline operation, the most appropriate compression during continuous operation and the heat transfer in the charge air reservoir 12. In any case, it must be taken into account that the heat exchange depends, among other things, on the mass of the participating bodies. The higher this mass, the more effective the heat exchange is. Since the pistons 4, 5, 6 are firmly connected to one another, the delivery capacity of the charge air pump 3 can thus only be determined by changing the working surface of its compressor piston 6.

The charge air now entering the charge air reservoir 12, that is to say the jacket space which is formed by the cylinder wall 23 and the outer jacket 11 of the cylinder, is heated by the prevailing temperature of the cylinder wall 23 and the cooling fins 53. As a result, this charge air acts as a coolant for the cylinder wall 23, and thus a maximum temperature in the cylinder 1 is made possible, which lies far above the deformation limit of the cylinder wall. It is known that the higher the starting temperature for thermodynamic machines, the better their efficiency. It should also be noted that due to the preheating of the charge air in the jacket space 12, part of the heating of the charge air is anticipated, which heating is one of the effects desired by the compression of the charge air in the cylinder. On the other hand, this warming causes the molecules to move more naturally. As a result, the charge air that enters the cylinder at the start of the work cycle is preheated. The further heating by compression up to the ignition temperature therefore requires a shorter piston stroke and therefore less energy than if the charge air had a normal outside temperature would enter the cylinder. The pressure of the charge air pump 3 ensures that the amount of air flowing from the jacket space 12 into the cylinder 1 is adequately dimensioned despite heating.

The charge air density desired in conventional internal combustion engines (which is achieved in conventional engines, inter alia, by cooling the charge air) is achieved in the present internal combustion engine in part by an oversized charge air quantity. In the present internal combustion engine, the air-fuel mixture is lean. This means that a larger amount of charge air is fed into the cylinder 1 than is necessary for the complete oxidation of the fuel. Thus, the thermal energy released during the combustion is not only distributed to the combustion products including the nitrogen, which corresponds to the oxygen consumed, but also to the excess oxygen not participating in the combustion and the corresponding amount of nitrogen. In the case of a lean mixture, including the resulting residues, this means that the maximum permissible temperature in the cylinder is not exceeded. The catalysts in the combustion chambers ensure a more complete oxidation of the fuel, ie its chemical components. This means that there is no leakage of pollutants that result from incomplete oxidation, or the formation of the pollutants is at least reduced. In diesel engines, for example, platinum in the combustion chamber promotes the conversion of carbon in diesel oil to carbon dioxide (C0 ₂ ). Soot formation is also counteracted, since soot is free carbon. For petrol engines Nitrogen oxides form during combustion. A corresponding catalyst, which is currently used in the exhaust, promotes the dissolution of the stock oxide in its components. If such a catalyst were now arranged in the combustion chamber, it would hinder the formation of nitrogen oxides and help to dissolve nitrogen oxide that has already formed. The catalyst material is applied to ceramic grids and thus installed in the combustion chamber. The amount of heat that would then be lost in the combustion chamber if endothermic compounds, such as nitrogen oxides, arise, or if carbon only burns to carbon monoxide, is now retained or is released. It can now be converted into kinematic energy in the engine for conversion.

Non-knock-resistant gasoline with a low octane number is used when the internal combustion engine is operating. However, the ignition also takes place here according to the diesel principle, the charge air compressed in the cylinder has a temperature which is sufficiently high for the reasons mentioned above to enable the chemical reactions, i.e. the combustion, when the fuel is injected. There is obviously no further explanation for diesel operation. Knocking the internal combustion engine is impossible because the working piston 4 is not connected to a crankshaft.

The fuel is not injected as quickly as possible, but in a metered manner, so that the pressure in the respective combustion chamber drops as slowly as possible, in order then to drop sharply when the fuel supply is ended and the outlet slots 57 are subsequently released. The reason for this is that such a pressure curve is easier to compensate in a cyclical sequence.

After the combustion has taken place and the outlet slots 57 have been released, the combustion flows gases into the exhaust pipe 58, on which the lubricating oil pan 56 is arranged laterally, and then through the exhaust 62 into the open.

With each combustion in one of the combustion chambers 9, 10, the piston 4 is moved against the opposite combustion chamber. In this combustion chamber, the charge air is compressed by the piston. At the same time, due to the movement of the piston 4, the corresponding movements of the pistons 5, 6 connected to the latter take place. After the piston 4 has completed a certain stroke distance, it releases the outlet slots 57. Even before the outlet slots 57 were opened, the gas in the respective combustion chamber had cooled down due to work performed, namely the conversion of the thermal energy of the gas (pressure resulting from the inherent movement of the gas molecules) into kinetic energy (force of the piston movement), and thus has cooled down the gas pressure also decreased. When the outlet slots 57 are released, the pressure that prevails in the respective combustion chamber suddenly drops. The respective inlet valve 20 or 21, which connects the charge air reservoir 12 to the respective combustion chamber 9, 10, is thus opened and new fresh air can flow into the respective combustion chamber and flush the remaining amount of the combustion gases out of the cylinder 1 through the outlet slots 57.

The course of the liquid during continuous operation of the internal combustion engine is as follows. The piston 5 of the liquid piston pump 2 conveys the liquid into the outlet line 70 through the respective outlet valve 25, 27. The working surfaces of the pistons of the fuel injection pump 39 and of the two lubricant pumps 44, 47 are open towards the outlet line 70, that is, the liquid in the outlet power 70 can act on these three pistons. With each pump stroke of the piston 5 of the liquid piston pump 2, the three pistons 40, 49, 51 are moved against the force of their respective springs and thus pump the fuel or the lubricant. When the piston 5 of the liquid pump 2 reaches one of its dead centers and thus there is a pressure drop in the outlet line 70, the three pistons 40, 49, 51 are moved back into the starting position by their respective springs 41, 50, 52 and the liquid to be pumped is sucked in. The liquid in the outlet line 70 flows through the change-over valve 88 and then to the air tank 60. Air under pressure is present in the air tank 60. The liquid flowing out of the outlet line 70 is introduced into the lower region of the wind chamber 60. Since the supplied liquid is under pressure, the air pressure above it in the wind chamber 60 is increased. The liquid outlet of the boiler 60 is equipped with a throttle valve 64. This throttle valve 64 is controlled by a pressure sensor 63, which senses the pressure present in the air tank 60. The pressure sensor 63 controls the throttle valve 64 in such a way that the higher the pressure in the air tank 60, the smaller the valve opening. As a result, the cyclical changes in the fluid pressure originating from the pump 2; largely balanced.

The liquid flows from the air chamber 60 through the above-mentioned throttle valve 64 to the liquid turbine 66, in which the pressure, which results from the kinetic energy of the liquid, is converted into the force of the rotating turbine shaft in a known manner. After the liquid turbine, the liquid flows through the return line 68 to the inlet valve 24 or back to the inlet valve 26 of the liquid pump 2.

A variant of the embodiment is shown in FIG. 2. It is assumed that there are no catalysts in the combustion chambers 9, 10.

In this variant, a catalytic converter 90 is used in the exhaust pipe 58. However, the exhaust pipe 58 does not lead directly to the outside, but is fed to an exhaust gas turbine 91, from which the exhaust pipe 62 leads to the outside. The exhaust gas turbine 91 is connected to a pump wheel 92 via a shaft 94. The liquid flowing through the outlet line 70 flows, as in the variant according to FIG. 1, into the wind chamber 60 and from there through the throttle valve 64 into the turbine 66 with the output shaft 67.

According to the variant according to FIG. 2, the outlet of the turbine 66 is now fed to the pump wheel 92 via the return line 68.

The liquid flows back from this pump wheel 92 to the liquid piston pump 2 (see FIG. 1). By using the energy present in the exhaust gas, the efficiency of the internal combustion engine is improved.

If the load of the internal combustion engine is increased or the fuel supply is reduced, the stroke of the piston 4 is also reduced, and thus the output of the liquid piston pump 2 and the charge air pump 3 is also reduced. In order to ensure, however, that even with a shorter stroke of the working piston 4, a sufficient amount the charge air is promoted, the charge air pump 3 must be oversized. _D a, however, then in a continuous operation would set too high overpressure in the charge air storage 12, the safety valve 14, which works as a pressure relief valve, arranged, through which escapes such excess amount of air into the open air, the If there is excess air pressure due to malfunctions due to a lack of lubricating oil or excessive wind pressure on the intake manifold of the charge air pump 3.

At a reduced stroke length of the piston 5 of the liquid piston pump 2, but also a correspondingly reduced delivery rate of the fuel injection pump is obtained 39. For this reason, the _B racing fuel injection pump 39 oversized. The operation of the fuel injection pump 39 is controlled by means of the fuel throttle valve 73 and the safety valve 74. This makes it possible to control the amount of fuel supplied to the cylinder 1 independently of the stroke of the piston 40 of the fuel injection pump 39. If the stroke of the piston 40 of the fuel injection pump 39 is reduced, there is a pressure drop in the pump, which is sensed by the pressure sensor 72 and correspondingly opens the fuel throttle valve 73 more. If the stroke is greater, the pressure sensor 72, which senses the correspondingly higher pressure, causes the throttle valve 73 to close. If the pressure inside the fuel injection pump 39 rises above a predetermined value, the safety valve 74 opens, so that excess fuel quantity returns to the fuel supply pipe 48 or alternatively is returned to the fuel storage tank. If the fuel injection pump 39 were not equipped with the pressure sensor 72 and the throttle valve, the engine would switch off due to an insufficient amount of fuel in the case of arbitrary, for example, manual throttling of the fuel supply. When arbitrary example, manual increase of fuel supply would be the internal combustion engine to greatly Heat _n .The pressure sensor 72 to the throttle valve 73 prevents this overheating by the amount of fuel supplied bumper is matically reduced. This means that if the fuel throttle valve 73 was controlled by manual actuation into a position that would not supply the amount of fuel measured for continuous operation of the internal combustion engine to the cylinder 1, this incorrect position is immediately corrected by the control arrangement formed by the pressure sensor 72 and throttle valve 73.

The free-piston internal combustion engine is characterized by a number of advantages. First, it has high thermal efficiency. The stroke length of the piston 4 is variable, but the combustion force is inelastically related to the power output by the turbine shaft 67 by the combination of the liquid pump 2 and the turbine 66. The energy is transferred by a liquid and, as is well known, liquids are liquids incompressible in practice, while gas is compressible and therefore elastic. Since the energy is generated by a free-piston engine that operates the liquid pump 2, and since the piston stroke is not prescribed by the connecting rod and crankshaft, the piston stroke can adapt optimally to the load. With a constant piston stroke and variable load, force is lost if the load is less than the piston and stroke can cope with at maximum. If the load is too high, it is known that the engine stalls if, in the case of a transmission, the same is not shifted in time. The utilization between two gear stages is never optimal. The inelastic hydraulic coupling between the load and the free-piston engine with variable stroke, on the other hand, reduces energy losses, as well as losses caused by other undesirable side effects, such as pressure gradients in gases. Furthermore, no additional energy has to be compensated for in this internal combustion engine unwanted form of energy are used, which is the case for example in conventional internal combustion engines due to the cooling required there. Catalysts are either arranged in the combustion chambers so that the chemical energy of the fuel is fully utilized there, or a catalyst is then arranged in the exhaust pipe.

Furthermore, the internal combustion engine is characterized by a great simplicity of construction. It has only two large moving parts, namely the arrangement consisting of the three pistons and the turbine rotor. This allows the internal combustion engine to be produced inexpensively and is obviously not very susceptible to faults. The various valves are largely self-controlled, spring-loaded, commercially available units. Where an automatic valve control takes place, the corresponding device is constructed as simply as possible. Manual control is basically limited to one valve, namely the fuel throttle valve 73, ie when starting up to four valves (in addition to the fuel throttle valve 73, the changeover valve 88, the vent valve 35 and the shutoff valve 34). The fuel engine can basically be built with only a single cylinder. The wind boiler 60, together with the valve 64, ensures that the liquid flow entering the turbine 66 is not subject to major pressure and quantity changes. If a flywheel had to be used for the uniformity of the rotation 7, the turbine rotor could be constructed so heavily that it itself could serve as a flywheel. If the weight of the internal combustion engine and the fuel costs are not the first priority, the turbine can be designed as a Pelton-Turibne. For a long time Continuous operation is sufficient for an impeller turbine. A Kaplan turbine is used for variable loads. With the latter, the internal combustion engine then has an infinitely variable energy transmission device.

The internal combustion engine is inexpensive, since only a few parts of the same have to be made from substances to which special demands are made. The cylinder 1 is made of a heat-resistant, highly thermally conductive material that is resistant to elastic deformation, for example of an SiAl alloy. The working piston 4 of the cylinder, as well as the inlet valves to the cylinder and in particular their springs are made of a heat-resistant material. Finally, the wind boiler also consists of a good heat-conducting material. All other components of the internal combustion engine can be made of steel and / or duralumin and cast iron. Furthermore, with the exception of the valves arranged on cylinder 1, all valves are standardized products which are freely available commercially. Furthermore, the manufacture of the internal combustion engine only requires simple manufacturing processes, no expensive and difficult to machine materials and also no special tools.

In addition, the internal combustion engine can be built very compact. In order to deliver an acceptably balanced output, basically only one cylinder 1 is necessary. Each cycle of the free piston is a compression cycle and a work cycle at the same time. Although the machine works as a two-stroke engine, there is twice the power output per unit of time compared to a conventional single-cylinder time-cycle engine and four times that of a single-cylinder four-stroke engine. In the liquid piston pump 2 and in the charge air pump 3, too, each cycle is simultaneously an intake and a work (pump) cycle When the cylinder is flushed, the combustion gases are emitted more completely than with a four-stroke engine, because with the four-stroke engines there is always a gas residue in the cylinder section at the top dead center position of the piston.

Claims (9)

1. Free-piston internal combustion engine, with at least one cylinder (1), with a longitudinally displaceable, double-acting working piston (4) therein, and with a charge air pump (3), characterized in that the cylinder (1) to form a charge air reservoir (12 ) has an outer jacket (11) that the charge air pump (3) has a double-acting compressor piston (6) which is connected to the working piston (4) via a piston rod arrangement (7, 8), and which charge air pump (3) has a Charge air line (16) is connected to the charge air accumulator (12). 2. Free-piston internal combustion engine according to claim 1, characterized in that in the charge air reservoir (12) forming, between the outer jacket (11) and the wall (23) of the cylinder (1) located jacket space, the outer jacket (11) with the cylinder wall (23 ) connecting cooling fins (53) are arranged, that a main charge air inlet valve (22) is arranged in the outer casing (11), through which the charge air supplied through the charge air line (16) enters the charge air reservoir (12), that the cylinder (1) at one End has a first (9) and at the opposite end a second combustion chamber (10), in the cylinder wall (23) a first one (20), the charge air reservoir (12) with the first combustion chamber (9) and a second one, the charge air reservoir (12 ) with the second combustion chamber (10) connecting charge air inlet valve (21) is arranged, and that the combustion chambers (9, 10) are connected to an exhaust pipe (58) via exhaust slots (57). 3. Free-piston internal combustion engine according to claim 1, characterized in that the piston rod arrangement (7, 8) is connected to a double-acting piston (5) of a liquid piston pump (5), the outlet line (70) of which is fed to a wind boiler (60) which is connected to a liquid turbine device (66, 67), the outlet of which is connected to the liquid piston pump (2) via a return line (68). 4. Free-piston internal combustion engine according to claim 3, characterized by a fuel pump device (39) with a spring-loaded piston (40) and a lubricant pump device (44, 47) with spring-loaded pistons (49, 51), which pistons (40, 49, 51) have the outlet line (70) is acted upon by the liquid conveyed by the liquid piston pump (2) in such a way that each pump device (39, 44, 47) is driven by the liquid piston pump (2). 5. Free-piston internal combustion engine according to claim 4, characterized by a starting device with a starting cylinder (36) and arranged longitudinally displaceably therein, via a piston rod (38) with the piston (40) of the fuel pump device (39) connected starting piston (37), which starting cylinder ( 36) is connected via an air supply line (33) with a shutoff valve (34) to the charge air reservoir (12) and has a vent valve (35), which valves (34, 35) are actuated by a control device (43, 86) actuated by the starting piston (37) , 87) are controlled. 6. Free-piston internal combustion engine according to claim 5, characterized in that the control device (43, 86, 87) has spring-loaded swivel arms (86, 87) which are connected to the shut-off valve (34) or ventilation valve (35) and through longitudinal slots (46) of the starting cylinder (36) protrude into the interior thereof, which swivel arms (86, 87) can be deflected by the starting piston (37). 7. Free-piston internal combustion engine according to claim 3, characterized in that a changeover valve (88) is arranged in the outlet line (70) of the liquid piston pump (2), which is when the internal combustion engine starts up in a switch position in which the outlet line (70) Liquid piston pump (2) is directly connected to the return line (68) while bypassing the liquid turbine device (66, 67) on the liquid side. 8. Free-piston internal combustion engine according to claim 2, characterized in that a catalyst (15, 17) is arranged in each combustion chamber (9, 10). 9. Free-piston internal combustion engine according to claims 2 and 3, characterized in that in the exhaust pipe (58) a further catalyst (90) is arranged and the exhaust pipe (58) is fed to an exhaust gas turbine, the turbine wheel (91) with a liquid pump wheel (92) is connected to the drive, which requests the liquid flowing out of the liquid turbine (66) through the return line (68) to the liquid piston pump (2).

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