DE19922217A1 - Internal combustion engine producing little exhaust gas, with pump device in form of piston pump with at least one driven piston in closed pump cavity - Google Patents

Abstract

The engine (1) has a combustion cavity (9) for the periodic combustion of a fuel-air mixture and a pump device (16) supplying the fuel-air mixture to it. The pump device is in the form of a piston pump with at least one driven piston (23) in an enclosed pump cavity (21, 22). The piston is connected to a drive (24) in the pump cavity.

Description

The invention relates to an internal combustion engine, in particular others with spark ignition.

Internal combustion engines are subject to strict exhaust gas legislation. Even small and simply constructed internal combustion engines, such as two-stroke engines for motor devices or the like, may only have a small proportion of hydrocarbons (HC), CO and NO _x in the exhaust gas. Therefore, simply constructed (inexpensive) powerful engines with good exhaust gas quality are sought.

DE 37 44 609 A1 describes a low-pressure fuel injection known for a two-stroke engine. This two-stroke motor uses the crankcase as an inlet duct and pump. He sucks in pure air and conveys it into the combustion chamber. A Injector is opposite the outlet slot in the top ren area of the overflow channel arranged. The injector is supplied with petrol by a fuel pump. The Fuel is injected with the outlet slot open. Rinsing losses can therefore hardly be avoided. The result is Koh Hydrogen oils in the exhaust gas (HC emission).

From DE 195 27 628 A1 a two-stroke engine is known is provided with a mixture blowing device. The one injection opening for blowing a gasoline-air mixture into the The combustion chamber is below the top edge of the outlet slot. Flushing losses are possible.

Internal combustion engines usually need to be in a wide range Speed and load range from training run to maximum speed and can be operated from zero load to full load. The exhaust gas quality should be good in all aspects of this operating area. This it is important to achieve it with simple means.

As far as two-stroke engines as in DE 37 44 609 A1 or DE 195 27 628 A1 can lead air through the crankcase additional problems with the lubrication of the Mo tors, which are also simple but reliable sieren is. If the air carries lubricating oil, HC emissions can occur be the result.

This results in the basis of the invention Task, a simple practical engine with good Ab to create gas quality.  

This object is achieved by three in the claims 1, 7 and 10 alternative measures resolved, each one individual measure essentially solves the task. The optimum is achieved by combining all three measures Claim 1, 7 and 10 reached.

According to claim 1, the motor with a pump device provided, which promotes the mixture in the combustion chamber. The Pumpein direction is designed as a piston pump and has at least a mixed-flow pump room, preferably two through an overflow channel connected pump spaces, the An driven the pump piston in the pump chamber (one of the pump chambers) is arranged. With mixed lubrication that lubricates through the Pumped fuel-air mixture also pumped the drive the pumping device, so that it is easily and cheaply opened can be built. For example, a trade will be used as a pumping device usual modified miniature two-stroke engine from a few Ku displacement used. Instead of an outlet This converted miniature two-stroke engine has a slot a check valve connected to its cylinder head on that the mixture is pumped to the internal combustion engine becomes.

Such a pump device is simple, kos affordable and robust. It also causes one good mixture formation. It is preferably from the cylinder, especially the cylinder head of the internal combustion engine thermally Cut. The mixture can thus be relatively cool in the combustion chamber be blown in.

The pump device preferably only conveys the mixture after closing the outlet slot in the combustion chamber. The one spray opening is arranged above the outlet slot. This prevents flushing losses.  

The pump device is preferably on the suction side adjustable mixture generating device, for example a Verga water, connected. This is preferably set in bold. Additional combustion air can be in the internal combustion engine are otherwise led into the combustion chamber, for example via a Intake stroke (four-stroke principle) or through the crankcase (Two-stroke principle). The Ge promoted by the pumping device mix and give the air that otherwise came into the combustion chamber overall the ignitable mixture of the desired composition tongue. The mixture pump can be very small with this division being held. E.g. can a Hubvo in the embodiment lumens are sufficient, less than 1/10 to 1/20 of the stroke volume of the operated cylinder.

Another contribution, the simply structured burning Low-emission engine to make, lies according to claim 7, that besides the pumping device to supply the motor with Fuel or air-fuel mixture is another mixture generating device is provided, which has a separate Lead the inlet channel of the through the crankcase, for example can be used to supply the motor. The Ge Mixing device can be a carburetor. This about preferably takes the idle and part-load operation, so that the pumping device only for higher loads and for full is responsible. The pumping device is therefore only subject to low tolerance requirements. The one taking over the idle Carburetor enables stable idling, due to the freshness introduced here only in the engine gas quantities the purge losses are naturally low. Also in This results in an exhaust gas with low HC values when idling.

Regardless of whether the internal combustion engine with a Ben fuel injection, a mixture feed pump and possibly one too additional idle carburetor is equipped or without it the crank mechanism and the piston must be lubricated  the. This can be done with very small amounts of oil low HC values can be achieved.

A piston divided according to claim 10 enables Lubrication with very small amounts of oil, which in turn is the Ab gas quality benefits. By between the piston crown and Piston shirt-trained slit can be lubricant-laden Get air from the crankcase onto the tread, whereby it leaves lubricant on the tread. Especially this principle is simple to apply when using the crank at least a small amount of fuel is supplied to the housing, which also contains lubricant. However, the principle is also applicable when the air is pumped through the crankcase or the fuel-air mixture via a fresh oil metering pump Lubricant has been supplied.

The separation of the piston crown and piston skirt causes also a reduction in heat transfer and Ent coupling with regard to thermal expansion. This allows the Lubricant requirements can be reduced. In addition, the heat transmission to the treads reduced. Conversely means this is a reduction in the cooling of the piston crown, which is what if an improvement in exhaust gas quality through lower CO-Ent winding enables.

The piston crown can be designed like a valve, so that the slot only allows gas quantities to flow through in pulses. The sink However, the combustion chamber is mainly developed via others wide channels, for example a conventional overflow channel leads from the crankcase into the combustion chamber. The maximal Width of the formed between the piston crown and piston skirt The gap limits the amount of gas flowing through it in comparison to the entire ge from the crankcase into the combustion chamber produced gas quantity to a fraction of a few, at most 5 to 10%.  

It is possible to use the piston crown as an automatic (self-controlled) or externally controlled flush valve to nut Zen. Especially at higher speeds, the An part of the not through the overflow channels but through the Increase the amount of gas fed into the combustion chamber. Rinse can lusts here by an appropriate design of the Piston overflow valve are counteracted preferably occupies almost the entire piston crown. E.g. can between the piston crown (= valve closure member) and piston shirt formed slot near the Outlet slot must be interrupted. With pure air purge however, this is superfluous. This also applies to an execution form, in which only with higher performance for air purge and for flushing with noticeable flushing through the piston part is passed over. The one flowing in through the piston Fresh gas or air flow can be used as a jacket on the tread flow along into the combustion chamber and this from the combustion chamber isolate. The result is a reduced thermal load tread, reduced heat loss from the engine and reduced fuel consumption. The combination of ge shared piston (claim 10) and mixture injection with air flushing (claim 1) and, if necessary, idle support Crankcase mixture flushing (claim 7) is advantageous.

Brackets can be used to fasten the piston crown Holders, springs, such as coil springs, disc springs, tension springs, Compression springs, spiral springs or the like are used. In particular it is appropriate to provide fasteners that are engage with the piston and / or the piston crown. This can be, for example, winding, snails or other springs where resilient latches are free. To assemble the Such elements only have to be prepared with the piston crown locked recordings.  

The advantages are as follows:

Improved lubrication through lower lubricant quantities with improved exhaust gas quality.

Thermal coupling between piston crown and piston skirt / ver reduced heat loss and lower fuel consumption.

Design of the piston crown as an automatic valve for a flow of cooling and lubricating air; if necessary for a purge air electricity.

Improved lubrication of the upper connecting rod eye Carrying out a lubricating air flow through a col ben / cooling of pistons and connecting rods.

Further details of advantageous embodiments of the Invention emerge from the drawing, the following Description or subclaims. In the drawing are off Illustrated leadership examples of the invention. Show it:

Fig. 1 shows a motor according to the invention in longitudinal geschnitte ner schematic diagram,

Fig. 2 piston and crank mechanism of the Mo tors according to the invention in exploded view;

Fig. 3 position of a modified embodiment of the piston and crank mechanism of the engine according to the invention, in Explosionsdar,

FIGS. 4 and Fig. 5 shows another embodiment of the piston and Col. bentriebs of the inventive engine, in a perspective schematic representation,

Fig. 6 shows another embodiment of the motor according to the invention in a partial schematic diagram,

Fig. 7 is a detailed view of the engine of Fig. 6 and

Fig. 8 serving as a connecting element winding spring, in perspective view.

An internal combustion engine 1 according to the invention is illustrated in FIG. 1. This is designed as an air-cooled single-cylinder two-stroke engine with cylinder 2 , cylinder head 3 , piston 4 , connecting rod 5 , crankshaft 6 and crankcase 7 . The gas exchange sel takes place via one or more overflow channels 8 , which lead from the crankcase 7 into the combustion chamber 9 defined above the piston 4 , and via at least one exhaust channel 11 , to which an exhaust with a silencer is connected. For this purpose, one or more inlet slots 12 and one or more outlet slots 14 are provided in the running surface of the piston 4 , which are controlled by the upper edge of the piston 4 who.

For fuel supply, a fuel system 15 is seen before, which includes a mixture feed pump 16 and a carburetor 17 . The mixture feed pump 16 is connected to the crank shaft 6 and is used to promote fuel-air mixture in the combustion chamber 9 , in which it burns ignited by a spark plug 18 via an ignition system 19 at a defined time. The mixture feed pump 16 is configured similarly to a two-stroke engine. In practice, a modified miniature two-stroke engine is used. It has a first pump chamber 21 and a second pump chamber 22 , which are separated from one another by a piston 23 . This is driven back and forth via a crank mechanism 24 which is connected to the crankshaft 6 . The first pump chamber 21 is connected to a carburetor 26 via an inlet slot 25 controlled by a piston edge, a rotary slide valve, a diaphragm valve or a similar device. This serves as a mixture generating device and can be regulated with regard to the quantity of mixture conveyed by the pump 16 .

From the first pump chamber 21, an overflow conduit 27 leads to the second pump chamber 22, wherein the overflow channel is released and closed controlled by the present in Fig. 1 below the upper edge of piston 27. A channel 29 leads from the pump chamber 22 , possibly via an automatic check valve 30, to an inlet opening 32 which is formed on the cylinder head 3 . The inlet opening 32 can be provided with a check valve 33 . With a correspondingly short design of all channels, the valves 30 and 33 can also be replaced by a single valve. Sliders or externally controlled valves can optionally be used. If necessary, the pump 16 can also make do with a single pump chamber 21 , in which, however, the crank mechanism 24 is arranged and is therefore lubricated by a fuel or fuel-oil mixture.

The second carburetor 17 is connected to the crankcase 7 via an inlet opening 34 . A diaphragm valve 35 , a rotary valve or the lower edge of the piston regulate the inlet. The carburetor 17 , which can be controllable via a throttle valve 36, supplies the engine 1 with a fuel-air mixture. He is there built in so that he flap at nearly closed throttle delivers 36 ignitable mixture while 36 ever leaner at increas mender opening of the throttle valve. E.g. the amount of fuel delivered is constant. The carburetor 17 therefore generates an ignitable mixture during low or partial load operation, while essentially releasing air at full load. If necessary, the fuel supply can also be completely cut off here.

To supply air to both carburetors 17 , 26 is a ge common air filter. Both carburetors 17 , 26 receive fuel from a common tank 42 , which contains a fuel-lubricant mixture.

The structure of the piston 4 essentially results from FIG. 2. The piston 4 has a piston head 45 , which is separated from the rest of the piston 4 . For this remaining part, an approximately bush-shaped piston skirt 46 is heard, which turns the piston piston 45 into a flat or frustoconical sealing surface 47 . To connect to a connecting rod 48 , a piston pin 49 is used for the corresponding receptacles 51 , 52 are provided, in which the piston pin 49 is axially secured via conventional springs 53 , 54 .

The piston crown 45 is formed as an approximately flat cylindrical disk and has two piston rings 55 on its outer circumference. To attach to the piston pin 49 short tabs 56 , 57 , which are riveted benboden 45 with an angled end to the Kol or are otherwise connected. In the assembled state, the piston crown 45 rests with its lower sealing surface 58 with little force on the corresponding sealing surface 59 of the piston skirt 46 . The inherent elasticity of the tabs 56 , 57 enables a gap of a few 10 millimeters to be formed between the two sealing surfaces 58 , 59 , corresponding to the pressure difference between the crankcase 6 and the combustion chamber 9 . The outer diameter of the piston crown 45 is dimensioned such that it does not jam even with the greatest tearing and expansion. In the cold state, the piston shirt 46 thus has a larger diameter.

In Fig. 8 a from a spring steel strip wound te coil spring 56 'is illustrated, which can be used instead of one of the tabs 56 , 57 for mounting and holding the piston crown 45 . If only one clock spring 56 'is used, this can serve as a hinge and at the same time pretension the piston crown against the piston skirt 46 . If two or more coil springs 56 'arranged around the circumference of the piston head 45 are provided, these can act as tension springs. They are the same spring and fastening element. The connection to the piston crown 45 and the piston skirt 46 is designed as a snap-in connection. While the leg gene in slot-like Ausnehmun, bags or guides are pushed, a can on the legs 56, 56 of the coil spring 56 b provided in the locking tongues 56 c engage undercuts, prevent retraction and so make the connection.

The motor 1 described so far works as follows:
When idling or at low load, the engine 1 is supplied mainly or exclusively with the fuel / air mixture via the carburetor 17 . In this respect it works like a conventional two-stroke engine with mixture flushing. However, the ignitable mixture quantities conveyed by the crankcase 6 are not too large and too rich, and thus the flushing losses are low, and the HC values are low.

The fuel is used for lubrication. Towards the end of a working stroke, the pressure in the crankcase 6 exceeds the pressure prevailing in the combustion chamber 9 at the latest after the outlet slot 14 has opened . The pressure present in the crankcase 7 allows the piston crown 45 to lift off somewhat from the other pistons 4 , as a result of which a part of the mixture can flow into the combustion chamber 9 through the gap 61 shown in FIG. 1. The narrow gap results in a high flow rate, which cools the piston crown and prevents the lubricant from striking the tread. In addition, excessive heat transfer to the remaining pistons 4 , in particular the piston skirt 46, is avoided. Therefore, the smallest amounts of lubricant are sufficient for effective lubrication. In addition, the gas flow indicated by an arrow 62 in FIG. 1 also leaves lubricant on the upper connecting rod bearing.

For increasing loads on the engine 1 , the throttle valve 36 is opened further. When the engine has reached about 5% to 10% of full load (it still works with at most 1/10 of its full power), the mixture supplied by the carburetor 17 begins to become leaner, so that the mixture purging gradually changes to air purging. The combustion chamber 9 is thus no longer supplied with a mixture via the overflow channel 8 at higher partial loads and full load, but rather with a very heavily emaciated mixture or with pure air. In the simplest embodiment, the then constant small amount of fuel supplied by the carburetor 17 is sufficient to lubricate the crank mechanism and the piston 4 even at full air throughput. However, flushing losses are reduced to an extremely low level.

At the transition to larger loads, the carburetor 26 that supplies the mixture pump 16 is opened more and more. The down-stroke of the piston 23, the first pump chamber 21 draws mixture from the carburetor 26, which is supported on the upstroke of the piston 23 through the overflow 27 into the pump chamber 22nd On the next downward stroke of the piston 23 , the latter conveys the mixture from the pump chamber 22 via the valve 30 and the channel 29 to the inlet opening 32 . The crankshaft 6 and the crank mechanism 24 are connected to one another in such a way that the piston 23 performs its pumping stroke after the piston 4 has closed the outlet slot 14 . It will thus blow 4 mixture into the combustion chamber 9 during the upward stroke of the piston. This mixture is over-greased and mixes with the air blown into the combustion chamber during the flushing process to form an ignitable mixture with the desired λ value. At full load, the engine 1 is supplied with fuel almost entirely via the carburetor 26 and the mixture pump 16 . The carburetor 17 allows at most about 5% of the fuel amount.

The exhaust gas quality is good due to extremely reduced purge losses. By thermal separation between the mixture pump 16 and the cylinder head 3 , the mixture is blown cold. The thermal separation of the piston crown 45 and piston shirt 46 allows the smallest amounts of lubricant to be used, which further burns the exhaust gas. The mixture pump 16 takes over the supply of the engine 1 only with increasing outputs, but not when idling. It is thus possible in a simple manner to meter the small amounts of fuel and mixture required for idling. The bundle of measures:

• - Double mixture generation with conventional supply at idle and fuel or mixture injection at full load, use of a conventional miniature two-stroke engine as a mixture pump and formation of a gap between piston crown 45 and piston skirt 46 for improved lubrication and mechanical separation of piston and piston crown with regard to radial forces enables a total the construction of a simple inexpensive two-stroke engine with clean exhaust gases. In each case, one of the measures mentioned in itself leads to a significant improvement in the exhaust gas quality of a corresponding two-stroke engine.

In Fig. 2 above is a somewhat simplified embodiment with a frustoconical sealing surface 58 of the piston crown 47 is illustrated. Further modified embodiments can be seen in FIG. 3. The difference is in the attachment of the piston rings 55 to the piston skirt 46 , the piston crown 45 having no piston rings. The tabs 56 , 57 for mounting the piston crown 45 are further modified. In place of the somewhat resilient web 65 formed in the lower region of the tab, a relatively hard compression spring 66 is preferably used here without or with little pretension. As illustrated above, the sealing surface can be conical or flat. In all cases, the piston crown 45 includes a relatively narrow gap of hardly more than 1 mm with the running surface.

FIGS. 4 and 5 illustrate other forms of execution of the fixing of the piston head 45 to the remainder of Kol ben 4. Starting from the piston crown 45 , two pins 68 , 69 extend through corresponding bores 70 to the front sides of the piston pin 49 , whereby they axially secure it. Then coil springs 71 , 72 , secured with spring washers 73 , 74 , sit on the free ends of the pins 68 , 69 . The piston crown 45 acts here as an automatic valve with a conical or planar sealing surface, which allows the mixture to pass from the crankcase 7 into the combustion chamber 9 . It is used to cool the piston crown 45 , to lubricate the tread and the upper connecting rod bearing and, by reducing thermal losses, also to reduce fuel consumption.

Instead of lubricating with a fuel-oil mixture, fresh oil can be metered in by adding oil to the intake air of the carburetor or by directly lubricating at least the lower connecting rod bearing. In this case, the carburetor 17 can be completely stopped at higher partial loads and only allow air to pass through, which further improves the exhaust gas quality. In addition, it is possible to let the air required for operation with large loads past the carburetor 17 through additional channels into the crankcase 7 . Such a channel can be controlled, for example, by throttle valves or sliders.

Fig. 6 illustrates a further embodiment with a slide 76 for controlling the lubricating slot in the piston 4. The piston crown 45 is largely rigidly held on the piston benhemd 46 , a gap 80 being defined between them, which continues as a gap 81 between the outer peripheral surface of the piston crown 45 and the tread. The control slide 76 , which is seated in a groove provided on the underside of the piston crown 45 , serves to control the gas transfer from the crankcase 7 into the combustion chamber 9 . Regarding the direction of movement of the piston 4 , the annular slide 76 is somewhat smaller than the groove, so that it can move against the piston 4 , as indicated by an arrow 77 . If it lies with its lower at its inwardly facing the annular shoulder 82 formed flat surface 83 on a corresponding sealing surface 84 of the piston crown 45 , any gas transfer from the crankcase 7 into the combustion chamber 9 is blocked. In contrast, the lower contact surface 85 of the Kolbenbo dens 45 is provided with radial grooves 86 , so that the gas transfer is possible when the slide 76 has lifted off from the piston skirt 46 and is supported on the surface 85 . In this way, the gap 80 , 81 controlled by the slide 76 automatically opens and closes according to the pressure difference between the crankcase and combustion chamber.

A spark-ignited two-stroke engine has a pump to improve its exhaust gas quality, which pumps the fuel or fuel-air mixture into the combustion chamber 9 after the exhaust port or valve has been closed. A converted miniature two-stroke engine is used as the mixture pump. Overall, the engine is simple and robust and has an improved exhaust gas quality. It is advisable to regulate the idle speed via a separate carburettor, which is connected to the crankcase of the two-stroke engine and only provides a basic load (idle speed).

A split piston with a slot between piston crown 45 and piston skirt 46 also benefits the exhaust gas quality. This enables the use of the smallest amounts of lubricant and increased piston crown temperatures with low heat loss from the engine.

Claims (25)

1. Internal combustion engine ( 1 ), in particular with spark ignition, with at least one combustion chamber ( 9 ) for the periodic combustion of a fuel-air mixture, and with a pump device ( 16 ) driven by the internal combustion engine ( 1 ) for introducing a fuel-air Mixture into the combustion chamber ( 9 ), characterized in
that the pump device ( 16 ) is a piston pump with at least one pump chamber ( 21 , 22 ) closed off by a driven pump piston ( 23 ), and
that the pump piston ( 23 ) is connected to a drive ( 24 ) arranged in the pump chamber ( 21 ). 2. Internal combustion engine according to claim 1, characterized in that the pump device ( 16 ) has two pump chambers ( 21 , 22 ) separated from one another by the piston ( 23 ), which are connected to one another by an overflow channel ( 27 ). 3. Internal combustion engine according to claim 1, characterized in that the mixture inlet in the first pump chamber ( 21 ) and the mixture transfer from the first pump chamber ( 21 ) through the overflow channel ( 27 ) into the second pump chamber ( 22 ) through the pump piston ( 23 ) is controlled by a control slide or by a valve and that the mixture transfer from the second pump chamber ( 22 ) into the combustion chamber ( 9 ) is preferably controlled by at least one valve ( 30 , 33 ), preferably a self-controlled valve ( 30 , 33 ), wherein the pump device ( 16 ) is preferably thermally separated from the cylinder ( 2 ). 4. Internal combustion engine according to claim 1, characterized in that the pumping device ( 16 ) has a preferably unchangeable delivery stroke, which is essentially fixed to a point in time after its outlet channel ( 11 , 14 ) is closed. 5. Internal combustion engine according to claim 1, characterized in that the pump device ( 16 ) is connected on the suction side to a mixture generating device ( 26 ) which generates a fuel-air mixture with a high fuel content. 6. Internal combustion engine according to claim 5, characterized in that the mixture generating device ( 26 ) with regard to the quantity of mixture dispensed and / or the quantity of fuel contained in the mixture is adjustable. 7. Internal combustion engine ( 1 ), in particular with spark ignition, with at least one combustion chamber ( 9 ), for the periodic combustion of a fuel-air mixture, with a controlled inlet channel ( 8 ) and with a pump device ( 16 ) driven by the internal combustion engine ( 1 ) ) for introducing fuel or fuel-air mixture into the combustion chamber ( 9 ) in a first way, characterized in that the inlet duct ( 8 ) is connected to a mixture generating device ( 17 ) via which, in addition to that of the pump device ( 16 ) delivered fuel or air-fuel mixture can be introduced into the combustion chamber ( 9 ) in a second way, at least temporarily. 8. Internal combustion engine according to claim 7, characterized in that the Ge connected to the inlet channel ( 8 ) generating device ( 26 ) is controllable with regard to the setting of the generated mixture amount or composition. 9. Internal combustion engine according to claim 8, characterized in that the mixture generating device ( 17 ) generates an ignitable mixture in unte ren partial load ranges, while it emits emaciated mixture or air in the upper part load ranges and at full load or the emitted mixture is emaciated by additional air admixture. 10. Internal combustion engine, in particular with spark ignition, with at least one cylinder ( 2 ) and a piston ( 4 ) mounted therein for defining a combustion chamber ( 9 ), with a crank mechanism ( 6 ) which is accommodated in a crankcase ( 7 ) un, and with an inlet or overflow channel ( 8 ) leading through the crankcase ( 7 ) into the cylinder ( 2 ), characterized in that the piston ( 4 ) is adjacent to its piston bottom ( 45 ) on its outer surface and / or the piston bottom opening slot ( 80 , 81 ) through which at least temporarily a connection between the crankcase ( 7 ) and the combustion chamber ( 9 ) is given. 11. Internal combustion engine according to claim 10, characterized in that the piston crown ( 45 ) is largely thermally insulated from the rest of the piston ( 4 ). 12. Internal combustion engine according to claim 10, characterized in that the piston crown ( 45 ) and the remaining piston ( 4 ) are structurally separate and define a circumferential slot ( 80 , 81 ) which is at most a few 10ths of a millimeter wide. 13. Internal combustion engine according to claim 10, characterized in that at least one from the crankcase ( 7 ) past the piston ( 4 ) in the combustion chamber ( 9 ) leading overflow channel ( 8 ) is seen before. 14. Internal combustion engine according to claim 10, characterized in that the piston crown ( 45 ) against the rest of the piston ( 4 ) is movably mounted. 15. Internal combustion engine according to claim 14, characterized in that the maximum stroke of the piston crown ( 45 ) against the remaining piston ( 4 ) is less than 1 mm and is preferably in the range of one or a few tenths of a millimeter. 16. Internal combustion engine according to claim 10, characterized in that the piston head ( 45 ) is resiliently held on the remaining piston ( 4 ). 17. Internal combustion engine according to claim 10, characterized in that the piston crown ( 45 ) rests on the rest of the piston ( 4 ) on an annular surface ( 58 ). 18. Internal combustion engine according to claim 10, characterized in that the piston crown ( 45 ) bears against the rest of the piston ( 4 ) without pretension and that the piston crown ( 45 ) is held on a plurality of holding elements ( 56 , 57 ), which preferably against each other opposite points of the piston crown ( 45 ) are arranged. 19. Internal combustion engine according to claim 10, characterized in that between the piston crown ( 45 ) and the piston benhemd ( 46 ) defined passage gap ( 80 , 81 ) is assigned a preferably annular slide element ( 76 ) which the gap ( 80 , 81 ) releases or closes, the slide element ( 76 ) preferably being controlled at least in part by the pressure difference between the crankcase ( 7 ) and the combustion chamber ( 9 ). 20. Internal combustion engine according to claim 19, characterized in that the slide element ( 76 ) is in contact with the tread and is controlled at least in part by the friction with the tread and / or is at least partly controlled by its inertia. 21. Internal combustion engine according to claim 10, characterized in that the piston head ( 45 ) extends to the tread and forms a gap with this, which corresponds to the gap that the remaining piston ( 4 ) delimits with the tread, or larger than This is. 22. Internal combustion engine according to claim 1, characterized in that the piston crown ( 45 ) with at least one Kol benring ( 55 ) is provided. 23. Internal combustion engine according to claim 1, 7 or 10, characterized characterized in that the lubrication consists of mixed lubrication is formed. 24. Internal combustion engine according to claim 1, 7 or 10, characterized characterized that a fresh oil metering pump for lubrication is provided. 25. Internal combustion engine according to claim 1 and 7 or Claims 7 and 10 or according to claims 1 and 10 or according to claims 1 and 7 and 10.