DE102009049755A1 - Lifting cylinder internal-combustion engine operating method, involves expanding partially combusted charge under volume increase of chamber and delivery of piston, and discharging combusted fresh charge from chamber - Google Patents

Abstract

The method involves filling an operating chamber (20) with fresh charge, and compressing the fresh charge provided in the operating chamber by a movable piston (12) under volume decrease of the operating chamber and overthrusting of the compressed fresh charge into inlet pressure chambers (28, 30). The partially combusted charge withdrawing from one of the inlet pressure chambers is expanded under volume increase of the operating chamber and operating delivery of the piston. The combusted fresh charge is discharged from the operating chamber. An independent claim is also included for a piston-type internal combustion engine.

Description

The invention relates to a method for operating a piston internal combustion engine and a piston internal combustion engine. A peculiarity of conventional reciprocating internal combustion engines, in particular reciprocating internal combustion engines, is that located in the working chamber or in the combustion chamber air-fuel mixture in the region of the top dead center of the piston, d. H. at approximately maximum compression, ignite and then burn as quickly and completely, so that as much of the heat of combustion as possible is converted by the piston in its movement to UT into mechanical work. In internal combustion engines with external mixture formation, in particular gasoline engines, care must be taken that in the area of the spark plug ignitable mixture is present. In internal combustion engines with internal mixture formation, d. H. Injection of the fuel directly into the combustion chamber is available only for a very limited time for mixture formation, which leads to incomplete combustion and increases the pollutant content in the exhaust gas.

The invention has for its object to provide a method and an internal combustion engine for its implementation, with the or the requirements for the fuel are reduced, the internal combustion engine is operated with different fuels, the efficiency of the engine is increased and the exhaust gas quality is improved ,

A first solution of the invention is achieved by a method according to claim 1.

The claim 2 is directed to an advantageous embodiment of the method according to the invention.

The claim 3 indicates a piston internal combustion engine to solve the relevant part of the invention task.

The dependent claims 4 to 11 indicate advantageous embodiments and further developments of the piston internal combustion engine according to the invention.

One aspect of the invention is that during the compression stroke in the working chamber compacted fresh charge in the area of the TDC of the piston does not ignite directly in the working chamber, but is stored in a separate from the working chamber admission pressure chamber, and there at least partially burns, while previously in another Pre-pressure chamber stored fresh charge exits during or after their combustion from the pre-pressure chamber into the working chamber and generates mechanical work under expansion and downward movement of the piston.

The term "fresh charge" is used in the context of this application both for fresh air and for fresh air, the fuel is added.

The invention is explained below with reference to schematic drawings, for example, and with further details.

In the figures represent:

1 3 is a schematic view of a section of a cylinder of a piston internal combustion engine according to the invention, perpendicular to the axis of a crankshaft,

2 the view of 1 in different positions of the piston to explain the function,

3 a basic construction of a pre-pressure valve,

4 Flow conditions on a pre-pressure valve according to 3 .

5 a schematic view of a modified embodiment of a pre-pressure valve,

6 a schematic view of another embodiment of a pre-pressure valve,

7 a schematic representation of the operation of a pre-pressure valve,

8th an alternative actuation of a pre-pressure valve,

9 a view similar to the one 6 with spark plug and injector,

10 a diagram of a mixture distribution in a pre-pressure chamber,

11 an internally cooled pre-pressure valve,

12 a two-stroke piston internal combustion engine according to the invention, and

13 a piston internal combustion engine according to the invention with three pre-pressure chambers.

1 shows a section through a cylinder 10 a reciprocating internal combustion engine according to the invention. In the cylinder 10 is a piston 12 movable back and forth over a connecting rod 14 with a total of 16 designated crankshaft is connected. An axis of rotation of the crankshaft is A designated. The cutting plane of the 1 is perpendicular to the axis of rotation A.

In the cylinder head of the cylinder 10 opens an inlet channel 18 , in its mouth in one above the piston 12 trained working chamber 20 at least one inlet valve 22 is arranged.

From the working chamber is an outlet channel 24 from. In the outlet of the working chamber 20 in the outlet channel 24 is at least one exhaust valve 26 arranged.

The arrangement described so far is known per se and is therefore not explained in detail.

According to the invention, two admission pressure chambers are provided on the cylinder head 26 and 28 formed, wherein a connection opening between the working chamber 20 and the admission pressure chamber 28 by means of a pre-pressure valve 32 can be shut off and a leading through the wall of the cylinder head connection opening of the working chamber 20 in the pre-pressure chamber 30 by means of a pre-pressure valve 34 can be locked.

In 1 not shown is a valve actuator for actuating the valves and a fuel supply device for supplying fuel. This fuel supply device may cause an external mixture formation by fuel above the intake valve 22 is supplied. Alternatively or additionally and advantageously, an internal mixture formation with fuel introduction takes place directly into the working chamber or preferably into the admission pressure chambers.

Based on the figure parts a) to j) of 2 The following is the function of the machine according to 1 explained, wherein for simplicity, the reference numerals of 1 only in 2i ) are inserted.

According to 2a ) the piston sucks 12 when cranked by a starter crankshaft 16 Fresh air through the open inlet valve 22 through. The admission valve 32 the admission pressure chamber 28 it is open. The other admission valve 34 is closed so that the associated admission pressure chamber 30 is tightly separated. The outlet valve 26 is also closed.

After the piston 12 has moved through the UT, begins according to 2 B ) the compression stroke during which the piston moves up into its TDC and compressed fresh air with the intake valve closed 22 , Exhaust valve 26 and pre-pressure valve 34 through the still open admission valve 32 in the pre-pressure chamber 28 About pushes.

When the piston 12 reached its OT ( 2c )) closes the admission valve 32 and opens the admission valve 34 , The inlet valve 22 and the exhaust valve 26 are still closed. After closing the admission valve 32 is in the compressed, in the pre-pressure chamber 28 Fresh air contained injected fuel and the now there located air-fuel mixture, if it has not reached its autoignition temperature, ignited by means of a spark plug, not shown. That in the admission pressure chamber 28 Caged air-fuel mixture can thus with complete gasification of the injected fuel and best possible mixture preparation with a strong increase in pressure in the admission pressure chamber 28 burn.

The crankshaft 16 is turned on by the starter, so that the piston 12 moved from his OT to the UT. Here are the inlet valve 22 and the exhaust valve 26 as well as the admission valve 32 still closed and is the admission valve 34 open.

Once the piston has reached its UT ( 2e )) opens the outlet valve 26 and stays open until the piston reaches its OT.

After reaching the TDC, the exhaust valve closes 26 and opens the inlet valve 22 , so according to 2f ) a new intake stroke begins. Once the piston has reached its UT, a new compression stroke begins, according to 2g ) in the working chamber 20 Fresh air through the now open form valve 34 in the pre-pressure chamber 30 About pushes.

Once the piston has reached its TDC ( 2h ) opens the admission pressure valve 32 and closes the admission valve 34 , The under high pressure and now at least largely, preferably completely, burned, in the admission pressure chamber 28 located charge flows through the open form valve 32 at high speed into the working chamber 20 and pushes the piston 12 under work to the crankshaft down. The starting process is completed; the internal combustion engine now gives off mechanical work.

As the piston moves down ( 2i )), is in the in the pre-pressure chamber 30 Compressed fresh air contained fuel injected and the resulting mixture, if it does not ignite itself, ignited by means of a spark plug, so that in the admission pressure chamber 30 during the combustion of the mixture and when the admission pressure valve is closed 34 a high pressure arises.

When the piston 20 has passed through its UT, opens the exhaust valve 26 and the burned charge is ejected ( 2y )).

Then begins a new intake, a compression with pushing the fresh air into the admission pressure chamber 28 and so on, so that the machine operates on a four-stroke cycle, but the fresh charge compressed by the piston is not ignited and burned directly in the working chamber in the area of the TDC of the piston, but stored during each of a power stroke, exhaust stroke and intake stroke in one of the admission pressure chambers is burned and there under high pressure development.

From the above, it can be seen that it is advantageous if the volume of the working chamber in the TDC of the piston is approximately zero, so that the entire compressed fresh air or fresh charge is pushed into one of the admission pressure chambers. For this to be possible, the admission pressure valves must open into the respective admission pressure chamber.

The method has been described above in such a way that fresh air is pushed into the respective admission pressure chamber and fuel is added to the compressed fresh air in the admission pressure chamber. The process can also be carried out with external mixture formation such that the fresh air sucked in during a suction stroke is already added to fuel. With external mixture formation, the fuel is advantageously slightly gasifying liquid fuel, such as gasoline, or is itself already gaseous.

The engine may be a multi-cylinder engine in which the crankshaft cooperates with a plurality of cylinders arranged in series, V-shaped or otherwise in a manner known per se.

The valve actuation can take place via a camshaft driven by the crankshaft at half crankshaft rotational speed, which actuates the valves via corresponding cams. It is understood that the control times are selected in a suitable manner and can be adapted, for example via phaser to respective operating conditions.

The volume of the admission pressure chambers 28 and 30 is considerably smaller than that of the working chamber in the UT of the piston and is advantageously between 1/10 and 1/20 of the volume of the working chamber 20 in the UT of the piston. The volume of the working chamber in the TDC of the piston is as small as possible and, for tolerance reasons, is for example less than 5% of the volume of the working chamber 20 in the UT of the piston of.

3 shows the example of the admission valve 32 and the admission pressure chamber 28 the structure and operation of a pre-pressure valve.

The valve valve designed as a pilot valve 32 has a valve member 35 as poppet valve with a valve plate 36 and a valve stem 32 on, which is sealed by a wall of the pre-pressure chamber 28 passed through. The valve plate 36 tapers in the direction of the admission pressure chamber 28 away cone-shaped and is made by a closing spring 40 in sealing contact with a corresponding mating surface or a valve seat 42 urged in the leading through the cylinder head wall connection opening 44 is formed by the admission pressure chamber in the working chamber. The valve stem 38 is outside the admission pressure chamber 28 with a lateral approach 46 formed by a cam 48 a camshaft 50 against the force of the closing spring 40 for opening the valve according to 4 can be pushed upwards. An unillustrated valve clearance compensation element is advantageously in the approach 46 arranged and serves as a contact surface of the cam 48 ,

• – Beim Ein- und Ausströmen von Ladung durch das geöffnete Vordruckventil hindurch entstehen starke Verwirbelungen 52 (4).
• – Die Montage des Vordruckventils ist aufwendig.
• – Am Ventilteller können sich Verbrennungsrückstände ablagern.
• – In der Vordruckkammer herrschender Druck drängt den Ventilteller in Anlage an den Ventilsitz, wodurch zum Öffnen des Vordruckventils bei hohem Druck in der Vordruckkammer hohe Kräfte erforderlich sind, was zu erhöhtem Verschleiß führt.
• – Eine gasdichte Abdichtung der Führung des Ventilschaftes in der Wand der Vordruckkammer ist nur mit hohem Aufwand möglich.

The construction of the admission pressure valve 32 according to 3 has the following characteristics:

• - When the charge flows in and out through the opened admission pressure valve, strong turbulences are created 52 ( 4 ).
• - The installation of the admission valve is expensive.
• - Combustion residues can be deposited on the valve disk.
• - Pressure prevailing in the admission pressure chamber forces the valve disk into contact with the valve seat, whereby high forces are required to open the admission pressure valve at high pressure in the admission pressure chamber, which leads to increased wear.
• - A gas-tight seal the leadership of the valve stem in the wall of the admission pressure chamber is possible only with great effort.

5 shows an embodiment of the pre-pressure valve, in which the problems described above are largely eliminated.

At the admission pressure valve 32 according to 5 is the valve plate 36 to avoid the in 4 shown turbulence aerodynamic or overall teardrop-shaped. The contour of the valve seat 42 is adapted to the drop shape.

The valve stem 38 has a thin area 54 on, in an enlarged diameter guide area 56 goes over, in turn, over a conically widening inclined surface 58 into an area from which the approach 46 protrudes.

The effective diameter of the valve seat, ie the diameter d (3) of the valve seat sealed in the closed position of the valve, is only slightly smaller than the diameter d (1) of the sealingly guided guide region 56 so that the pressure inside the admission pressure chamber 28 does not exert any significant force in the direction of movement of the admission valve. The force of the closing spring 40 is such that the closing spring 40 the admission pressure valve holds securely in the closed position against pressure prevailing in the working chamber. The inclined surface 58 lies in the closed state of the admission pressure valve on a corresponding inclined surface 60 the wall of the admission pressure chamber 28 on, so that through the two inclined surfaces 58 and 60 an additional valve 62 is formed, which is the admission pressure chamber 28 additionally seals to the outside. The maximum diameter d (2) of the valve disk 36 is advantageously not greater than the diameter d (1) of the guide region 56 so that the valve member 35 can be mounted from above.

6 shows a further development of the valve according to 5 , in which by repeatedly tapered design of the valve stem 35 in the transition area from the management area 56 to approach 46 and corresponding formation of the wall of the admission pressure chamber 28 a total of three additional valves 62 . 64 and 66 are formed, with the additional valves 62 and 64 close in the closed position of the admission valve and the additional valve 66 in the open position of the admission valve closes. With the training according to 6 in which the opening movement of the admission pressure valve through the additional valve 66 is limited, a secure seal of the admission pressure chamber 28 reached to the outside both closed and when open admission valve.

7 and 8th show two different embodiments of operations for the pre-pressure valve 32 or its valve member.

In the embodiment according to 7 has the shaft 35 of the admission valve 32 a guide opening 68 on, in which a sliding block 70 according to 7 is guided in a horizontal direction. The sliding block has a circular opening 72 on, in an eccentric disc 74 a shaft rotatably mounted about a fixed axis 76 , For example, camshaft, is added. Upon rotation of the shaft 76 the valve member moves 35 in a conventional manner up and down. The closing spring 40 can in the embodiment according to 7 absence.

In the embodiment according to 8th is the valve member 35 extended to the top, with the extension 78 has a ferromagnetic portion partially in an electromagnetic coil 80 protrudes. Upon energization of the coil, that of the valve spring 40 opened in closed position admission pressure valve opened. Instead of the closing spring 40 may be provided another solenoid, which is the admission valve 32 in the closed position urges. The entire construction may be in a manner known per se such that the valve member rotates by a predetermined angular amount about its longitudinal axis during each opening and / or closing stroke.

It is understood that other types of valve actuation are possible, such as pneumatic or hydraulic valve actuation.

9 shows the embodiment according to 6 an example in the pre-pressure chamber 28 protruding spark plug 82 and injector 84 are shown.

Concerning fuel supply and ignition, the following points should be noted:
Liquid or gaseous fuel can be injected directly into the pre-pressure chambers directly. It is also possible to add the fuel upstream of the intake valve to the fresh air, whereby, however, there is the risk that the fuel-air mixture ignites before the complete closing of the corresponding admission pressure valve. The engine can be operated as a naturally aspirated engine or as a supercharged engine.

To cool the pre-pressure valve, the fuel should be injected onto the valve member, most conveniently on the valve disk. This leads to a rapid evaporation of the fuel, which reduces the requirements for fine atomization during injection.

By evaporating the fuel from the surface of the valve member results in a soft layered combustion, which also makes it possible to use heavy-boiling fuels. If no autoignition takes place, it is advantageous to ignite a spark plug only after a delay after injection, so that sufficient fuel can evaporate and the admission pressure valve is effectively cooled. The spark plug can, depending on the operating condition, eg. B. at low speed, to be ignited during or after opening the admission valve. The ignition can be clocked, d. H. several times during the combustion process in the admission pressure chamber. This is particularly advantageous when working with excess air (without throttle) and is not always ignitable fuel-air mixture in front of the spark plug.

10 indicates the fuel-air mixture composition immediately after injection, with the in 10 not shown injection valve on the valve member 35 is directed. The reaching onto the valve member fuel evaporates and withdraws the valve member due to the heat of evaporation heat. Because of the evaporation of the fuel creates a stratification, as in 10 is shown, wherein the density of points represents the density of the fuel vapor, that of the surface the valve member in the pre-pressure chamber 28 decreases. For a reliable spark ignition of the initially inhomogeneous fuel-air mixture is advantageously a spark plug 82 used without ground electrode, at which the ignition current between the electrode of the spark plug 82 and the valve member 35 flows. On its way from the spark plug to the primary pressure valve, the spark penetrates layers of different mixture composition, so that mixture of optimum ignitability is safely ignited. It is understood that the valve member is constructed such that a secure electrical connection between it and ground, for example via the closing spring 40 , consists.

The admission pressure chamber and the admission pressure valve become very hot due to the combustion of the charge located in the admission pressure chamber, so that advantageously high-temperature resistant material is used. Nevertheless, a required cooling can be achieved by spraying lubricating oil on the outside of the admission pressure chamber located parts of the admission pressure valve, by cooling the admission pressure chamber with cooling water, passing through the pre-pressure chamber fresh air through the fuel evaporation, by heat conduction through the valve seat or seats and by sodium filling of the valve member Pre-pressure valve, whereby the described measures can be carried out separately or in combination. 11 shows a pressure chamber 28 with pre-pressure valve 32 , wherein the wall of the admission pressure chamber 28 with water-carrying cooling channels 86 is provided and the valve member 35 a sodium filling 88 having.

Depending on the fuel, the load control of the machine according to the invention can take place via the filling achieved per intake stroke and / or the added fuel quantity.

12 shows an embodiment of the engine according to the invention as a two-stroke engine, wherein in a conventional manner designed as a slot inlet valve 22 through one below the piston 12 trained crank chamber to a likewise formed as a slot overflow valve 90 leads and the exhaust valve 24 as according to 12 formed above the inlet slot outlet slot is formed. The admission pressure chambers with admission pressure valves correspond to the embodiment according to FIG 1 , The function of the admission pressure chambers corresponds to that of 1 , wherein a fresh charge in the respective admission pressure chamber is locked in each case only during a working and Verdichtungshubes.

13 shows an embodiment of the internal combustion engine similar to the 1 , but with three pre-pressure chambers 28 . 30 and 90 and correspondingly three admission pressure valves 32 . 34 and 92 ,

Due to the increased number of admission pressure chambers, the residence time of the fresh charge and the fuel added to it in the respective admission pressure chamber as well as the time available for the combustion can increase. When using heavy oil, for example, in this way an extended period of time for the complete gasification of the heavy oil and its combustion within the respective admission pressure chamber is available. The use of three pre-compression chambers allows a pre-pressure chamber to remain closed during two engine power strokes.

Depending on the engine design, the admission pressure chambers can be arranged in ring form or in series on a cylinder. In this case, different cylinders may be provided with a different number of form chambers to z. B. to reduce engine vibrations.

In case of failure of the operation of the pre-pressure valves, the engine can be operated with permanently open pre-pressure valves in a conventional manner.

The engine according to the invention, which can also be referred to as a pre-compression engine, naturally reacts to fast load changes more slowly than a conventional engine. In order to avoid this peculiarity, a post-injection into the just closed pressurized admission pressure chamber can take place during sudden acceleration, the total amount of fuel fed into the admission pressure chamber corresponding to the full load fuel quantity. The "accelerator fuel" can also be injected during the opening of the corresponding admission valve or shortly after its opening. In low-compression gasoline engines, it is possible to inject the fuel in sudden acceleration in the intake manifold, since in this case the fuel in the compression stroke does not ignite itself. Since the "accelerator fuel" usually can no longer ignite on the previously injected, already burned fuel, the spark plug at "accelerator fuel injection" must reignite accordingly (clocked ignition). In the diesel engine, the auto-ignition temperature in the admission-pressure chamber is usually exceeded by far, so that post-injection is easier here. Depending on the piston position and engine speed, it may be decided in an engine control unit (not shown) which option of "accelerator fuel injection" is most effective.

Even with overrun fuel cut the engine according to the invention reacts to the withdrawal of the accelerator pedal. In order to rapidly reduce pressure in the corresponding closed admission pressure chamber when the accelerator pedal is withdrawn, water can enter the Injected pressure chamber or the affected admission valve are opened briefly or little. This can be realized by means of an electromagnetic pre-pressure valve actuator.

An engine braking when Gaswegnehmen is possible by switching off the fuel injection and a suction throttle (throttle) in a conventional manner. In order to increase the engine braking effect, the braking effect can be enhanced with electromagnetic actuation of the pre-pressure valves and compressed air in each case in the pre-pressure chamber. This principle can also be used for anti-slip control.

To facilitate the cold start, a glow plug can be arranged in the admission pressure chamber in diesel engines. With the help of a glow plug in the intake manifold for heating the fresh air, the cold start behavior can also be improved.

In the pre-pressure chamber in addition to the fuel distilled water can be injected, the injection can be done with closed admission valve or at the beginning of a power stroke. The sudden evaporation of water creates additional working pressure, which increases engine performance and removes heat from the engine components. The removal of heat reduces the formation of nitrogen oxides. This may possibly be dispensed with exhaust gas recirculation.

In the following some advantages with the motor according to the invention are summarized:
The fuel has more time to evaporate and burn, which means it burns more completely, especially in excess air. This means reduced fuel consumption and improved efficiency.

The filling of the cylinder with fresh gas is improved because the temperature of the working chamber walls is reduced due to the combustion in the admission pressure chamber. When the throttle valve is omitted, the flow resistance is reduced. Furthermore, at least one of the admission pressure chambers is open in the intake stroke, so that the air volume which can be sucked in or pressed in during charging is increased. Overall, this results in less displacement more engine power.

Due to the combustion taking place exclusively in the admission pressure chamber, there is no danger of knocking and the compression can be maximized with regard to the mechanical load capacity of the components. Because of the high temperatures in the admission pressure chamber can be dispensed with an ignition system in many cases. Overall, the engine according to the invention can be run with cheaper fuel.

The engine according to the invention has fewer components, since in certain cases an ignition system, a catalytic converter, a lambda control and a throttle valve as well as a soot filter can be dispensed with.

Also, an external exhaust gas recirculation can be dispensed with appropriate control of the admission pressure valves, for example, at a power stroke the corresponding admission valve is only partially opened or clocked accordingly, so that at the time an intake stroke begins, the admission pressure chamber is not completely depressurized. Part of the exhaust gases thus flows into the cylinder during the intake stroke, as a result of which the temperature decreases in the event of subsequent combustion and less nitrogen oxides are formed. It has already been mentioned above that, instead of a complicated admission pressure valve control for the purpose of exhaust gas recirculation, additional water injection can be used.

In principle, internal exhaust gas recirculation in non-supercharged engines is also possible because the admission pressure valve, which is open during the power stroke, is also open in the intake stroke. Since a negative pressure in the cylinder occurs in the intake stroke, a portion of the remaining exhaust gases is sucked out of the open admission pressure chamber and fed to the fresh charge.

Since combustion takes place mainly in the cylinder head, there are fewer requirements with respect to piston cooling or turbocharger cooling.

Since the flame front does not lag the piston at high speeds, higher crankshaft speeds are possible.

The cooling system may focus on the cylinder head because of lower piston and exhaust temperatures. When opening the pre-pressure valve, the pressure in the cylinder increases softly, which leads to lower mechanical stress on the components and to a rounder engine run.

Since the fuel does not have to be atomized finely, there are lower requirements on the production accuracy of the injection system.

Due to the at least largely complete evaporation and combustion of the fuel in the respective admission pressure chamber of the combustion chamber or the working chamber is less contaminated by combustion residues, resulting in reduced engine friction and longer oil change intervals.

The embodiments listed above are merely illustrative of the invention and do not limit their embodiments. Within the scope of the teaching in particular of claims 1 and 3 numerous modifications and modifications are possible.

LIST OF REFERENCE NUMBERS

10

cylinder

12

piston

14

pleuel

16

crankshaft

18

inlet channel

20

working chamber

22

intake valve

24

exhaust port

26

outlet valve

28

form chamber

30

form chamber

32

form valve

34

form valve

35

valve member

36

valve disc

38

valve stem

40

closing spring

42

valve seat

44

connecting opening

46

approach

48

cam

50

camshaft

52

turbulence

54

Area

56

guide region

58

sloping surface

60

sloping surface

62

additional valve

64

additional valve

66

additional valve

68

guide opening

70

slide

72

opening

74

eccentric

76

wave

78

renewal

80

Kitchen sink

82

spark plug

84

injection

86

cooling channel

88

sodium filling

90

form chamber

92

form valve

Claims (11)

Method for operating a piston internal combustion engine with one of a movable piston ( 12 ) limited working chamber ( 20 ), to which at least two lockable admission pressure chambers ( 28 . 30 ), comprising the following steps: a) filling the working chamber ( 20 ) with fresh charge, b) compressing located in the working chamber fresh charge by means of the piston volume decrease of the working chamber and pushing the compacted fresh charge in one of the pre-pressure chambers, c) separating this one of the pre-pressure chambers of the working chamber and at least partially burning the fresh charge located in this pre-pressure chamber by increasing the pressure in this admission pressure chamber, d) connecting another one of the admission pressure chambers, in which step c) has taken place after a preceding compression stroke, with the working chamber, e) expanding the at least partially burned charge emerging from the other admission pressure chamber while increasing the volume Working chamber and working output of the piston and f) discharging the burnt fresh charge from the working chamber. The method of claim 1, wherein the internal combustion engine operates according to a four-stroke process and in one of the admission pressure chambers ( 28 . 30 ) superimposed, compressed fresh charge remains at least during a power stroke, exhaust stroke and intake stroke with at least partially combustion and pressure increase in this admission pressure chamber shut off from the working chamber pre-pressure chamber. Piston internal combustion engine comprising a piston reciprocable between a TDC and a TDC ( 12 ) limited working chamber ( 20 ), an inlet channel ( 18 ), whose inlet into the working chamber with an inlet valve ( 22 ) is closable, an outlet channel ( 24 ), whose outlet from the working chamber with an outlet valve ( 26 ) is closable, at least two pre-pressure chambers ( 28 . 30 ), whose connection to the working chamber in each case with a pre-pressure valve ( 32 . 34 ), wherein the volumes of the admission pressure chambers are smaller than the volume of the working chamber at UT located in the UT and the arrangement is such that during the movement of the piston from UT to TDC in the working chamber located fresh charge in one of the admission pressure chambers is überiebbar, a Fuel supply device ( 84 ) for supplying fuel such that the fresh charge located in the respective admission pressure chamber is combustible, and a valve actuating device ( 48 ; 50 ), which operates the valves such that the Piston engine according to a method according to claim 1 or 2 operates. Piston internal combustion engine according to claim 3, wherein the volume of the working chamber ( 20 ) with the piston located in the TDC ( 12 ) is approximately zero. Piston internal combustion engine according to claim 3 or 4, wherein the admission pressure chambers ( 28 . 30 ) at the piston ( 12 ) facing away from the working chamber ( 20 ) are arranged closing members ( 36 ) of the admission pressure valves ( 32 . 34 ) move into the respective pre-pressure chambers when opening the admission pressure valves. Piston internal combustion engine according to claim 5, wherein the admission pressure valves ( 32 . 34 ) as poppet valves with a from the inside of the respective admission pressure chamber ( 28 . 30 ) in sealing engagement with a valve seat ( 42 ) crowded valve disc ( 36 ) and a valve stem ( 38 ) are formed, which penetrates the admission pressure chamber and outside the admission pressure chamber with the valve actuator ( 48 ; 50 ) cooperates. Piston internal combustion engine according to claim 6, wherein the valve stem ( 38 ) in the region of its sealing guide through a wall of the admission pressure chamber ( 28 . 30 ) one the diameter of the valve seat ( 42 ) has similar diameter. Piston internal combustion engine according to claim 6 or 7, wherein the valve disc ( 36 ) is drop-shaped. Piston internal combustion engine according to one of claims 5 to 8, wherein the valve stem ( 38 ) outside the admission pressure chamber ( 20 ) with at least one additional inclined surface ( 58 ) is formed in the closed or open state of the pre-pressure valve ( 32 . 34 ) on an inclined surface formed on the wall of the admission pressure chamber ( 60 ) and with this an additional valve ( 62 . 64 . 66 ). Piston internal combustion engine according to one of claims 1 to 9, wherein the fuel supply device is an injection nozzle ( 84 ) contains the fuel in the admission pressure chamber ( 28 . 30 ) injects. Piston internal combustion engine according to one of claims 3 to 10, wherein in the admission pressure chambers ( 28 . 30 ) one spark plug each ( 82 ) is arranged without ground electrode and the ignition current between the spark plug and the pre-pressure valve ( 32 . 34 ) flows.

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