DE102019127495A1 - Reciprocating internal combustion engine with variable two-stroke / multi-stroke switching - Google Patents

Abstract

An electronically controlled reciprocating internal combustion engine is specified, which can work in the two-stroke process or multi-stroke process. The reciprocating internal combustion engine is implemented without a mechanical valve drive and is therefore particularly compact and simple in construction, inexpensive to manufacture and light. In addition, it runs with particularly low friction, particularly with regard to the lack of a valve train. At the same time, the variable switchover between two-stroke and multi-stroke operation, which is, for example, dependent on a performance requirement, minimizes consumption and emissions while at the same time achieving the highest maximum performance compared to conventional reciprocating internal combustion engines of similar size.

Description

The present disclosure relates to a reciprocating internal combustion engine which is designed in such a way that a switchover between a two-stroke operation and a multi-stroke operation can take place electronically in a demand-controlled manner.

In conventional two-stroke reciprocating internal combustion engines, one work cycle takes place for every 360 degrees of crank rotation through the ignition and combustion of an air-fuel mixture. A gas exchange normally takes place with the piston at bottom dead center. In the case of four-stroke reciprocating internal combustion engines, on the other hand, a working stroke with combustion only takes place every 720 degrees of crank rotation. After the work cycle, the exhaust cycle follows, followed by the intake cycle and the compression cycle.

DE 299 182 A1 discloses a four-stroke reciprocating internal combustion engine which is designed such that it can also be operated in the two-stroke process. In order to achieve switchability, the reciprocating internal combustion engine has two controlled exhaust ports in the cylinder wall in addition to an exhaust port in the cylinder wall that is customary for two-stroke engines and which connects the combustion chamber to the exhaust gas tract when the piston is at bottom dead center and thus enables exhaust gas to flow out of the combustion chamber Valves open. These are used as additional flushing valves in two-stroke operation. In four-stroke operation, as usual, one is used as an inlet valve and the other as an exhaust valve. Both valves are operated by a camshaft. Switching takes place by activating the camshaft at different speeds.

The object of the present disclosure is to specify an improved reciprocating internal combustion engine.

This object is achieved with a reciprocating internal combustion engine according to claim 1. Further developments are given in the dependent claims.

A great advantage of the reciprocating internal combustion engine according to the present disclosure is, for example, that on the one hand, with high power demand and possibly low speed, in contrast to a four-stroke reciprocating internal combustion engine, power is generated with combustion of fuel (gaseous or liquid) with each revolution of the crankshaft can. In this state, the low speed also results in only minor frictional losses. Conversely, if the engine speed is high or the power requirement is low, single or multiple revolutions can take place without combustion in order to increase the charge and reduce consumption. As a result of the combustion at each revolution, the speed can be significantly reduced, preferably halved, with the same power compared to conventional four-stroke reciprocating internal combustion engines, which means that there are lower friction losses. Because of the lower speeds, smaller gears, if necessary with fewer gear steps, etc., can preferably be used.

The switchover can, if required, preferably take place in real time, ie immediately. The reciprocating internal combustion engine according to the present disclosure preferably has the structure of a slot-controlled conventional two-stroke reciprocating internal combustion engine. It preferably has no cam and / or valve drive or works without cam and / or valve drive. It therefore works with little friction and is inexpensive to manufacture and easy to maintain. In addition, the size is particularly compact and the machine is light.

The choice of the respective cycle method enables a variable adaptation of the operation of the internal combustion engine to the respective requirement with the simplest construction of the machine at the same time. The power output can be adapted quickly, preferably in real time, to the requirements and finely controlled. The control of the cycle method (the selection of which cycle method is the most suitable) is preferably carried out via the power and torque requirements or, for example, emission requirements. The selection can be made to implement an engine stop or sailing function. For example, when accelerating, preference is given to switching to the two-stroke process and, after reaching the desired speed, switching to four or six-stroke.

Depending on the design, idle operation at a very low speed (for example in 6 or 8-stroke operation) can be provided in addition to or as an alternative to an automatic start-stop system. As a result, the requirements for the starter and battery can be reduced and heating or air conditioning can be maintained. In addition, the increased emissions with the automatic start-stop system can be prevented by cooling down during the stop phase.

Switching between operating methods (two-stroke cycle) can take place separately for each individual cylinder or for groups or all together and can be combined with conventional techniques (timing adjustment, variable compression, etc.).

Two or more single and / or multi-cylinder engines, which can be coupled, for example, via a clutch, can preferably be provided. To Acceleration, for example, all or groups of them work in two-stroke operation. At cruising speed, both or one of the motors switch to multi-stroke operation or even one motor is switched off completely and the other motor works in two-stroke or multi-stroke operation. As a further alternative, individual cylinders of each engine can be switched off.

The reciprocating piston internal combustion engine according to the present disclosure is therefore preferably smaller, lighter, safer (no oil in the double crank drive), and more economical and preferably has a lower complexity compared to known four-stroke reciprocating internal combustion engines with the same power. The switchability of the cycle processes enables a quick adaptation to the respective requirement. The lack of cylinder head control and lowering the engine speed can significantly reduce engine friction.

The reciprocating internal combustion engine is a single or multi-cylinder reciprocating internal combustion engine. An engine block, preferably with a cylinder head, forms one or more cylinders (cylindrical hollow bodies) within its walls, in which a piston can be moved back and forth. For each cylinder, a combustion chamber is preferably formed between the piston, cylinder wall and cylinder head (cover of the cylinder). The piston is preferably connected to a crankshaft directly via a piston rod or via connecting rods, etc. in such a way that a longitudinal movement of the piston leads to a rotation of the crankshaft. As a result, the piston is forcibly guided in such a way that it moves back and forth between an upper dead center and a lower dead center as the crankshaft rotates. Starting from its top dead center (here defined as 0 degrees of crank rotation) it moves from its top dead center to its bottom dead center and back again with a 360 degree crank rotation.

In the side cylinder walls (preferably formed mainly by the engine block), as is usual with conventional simple two-stroke reciprocating piston internal combustion engines, one or more outlet openings for gas in the combustion chamber and, preferably below the outlet opening, one or more inlet openings for preferably charged (with excess pressure ) Fresh charge (fresh air or fresh air-fuel mixture) provided. In the movement of the piston from the top dead center to the bottom dead center, the outlet opening is therefore preferably passed over by the piston before the inlet opening. If the piston (or its area serving to seal against the lateral cylinder wall) is below the upper edge of the respective opening, the opening is released into the combustion chamber. Since the inlet opening is arranged below the outlet opening, gas can first flow out of the combustion chamber and then fresh gas (air or air-fuel mixture) can flow into it. This process is also known as gas exchange. In the movement of the piston from its bottom dead center to its top dead center, the inlet opening is then closed first and then the outlet opening. In the further movement, after the openings have been closed, the fresh charge located in the combustion chamber is compressed. In the subsequent downward movement from top dead center to bottom dead center, the gas expands (possibly with combustion) and the process begins again.

The openings are preferably arranged in such a way that the incoming fresh gas can flush a large proportion of the gas located in the combustion chamber therefrom. For example, the openings are arranged opposite one another for this purpose. There can be several inlet openings and an independent number (even only one) of outlet openings. In particular, the inlet openings can be designed to be directed, so that the fresh charge flowing in flows in in a desired flow direction. In this way, for example, a vortex can be formed in the combustion chamber. The outlet openings can also be designed to be fluidically optimized.

An electronically controlled injection system is also provided, which is controlled by means of a control device (e.g. one or more control units). The injection system can be designed as a direct injection system or as an indirect injection system with internal or external mixture formation. The injection or the introduction of fuel itself is preferably regulated electronically via the control device; electronically regulated injection nozzles are preferably used.

In contrast to conventional two-stroke reciprocating internal combustion engines, the electronically controlled injection system is controlled as required in such a way that various cycle methods can be set.

When the two-stroke process is set, the reciprocating internal combustion engine according to the present disclosure operates like a conventional two-stroke reciprocating internal combustion engine. That is, for every 360 degrees of crank rotation (here, for example, starting from the piston located in bottom dead center), an injection process controlled by the control device takes place. As is customary today, an injection process can consist of a plurality of individual injections or a continuous injection; a change in the type of injection during operation is also conceivable. When training as a direct injection system, the injection begins, for example at the time when the piston reaches top dead center. In this context, every 360 degrees of crank rotation does not mean that this is calculated based on the piston located in top dead center, but that, starting from the start of an injection process to the start of the next injection process, with an intervening gas exchange, there are essentially 360 degrees of crank rotation, with the following Injection can also be earlier or later than exactly 360 degrees of crank rotation. An injection process is therefore preferably provided between two successive charge changes (preferably pistons in the area of bottom dead center) in the two-stroke process.

For example, ignition takes place more or less simultaneously with or shortly after the injection. As a result of the combustion, the air-fuel mixture in the combustion chamber expands, which leads to a downward movement of the piston (also known as the work cycle). In the downward movement of the piston, after the combustion, the exhaust gas can first at least partially flow out of the outlet opening and then fresh air can flow in from the inlet opening. A large part of the exhaust gas is preferably flushed out of the combustion chamber. Depending on the speed and construction, however, in many cases part of the exhaust gas remains in the combustion chamber due to the principle involved. In this case, a mixture of exhaust gas and fresh cargo is burned in the next job market.

When the multi-stroke process is set, the reciprocating internal combustion engine according to the present disclosure works as follows: on a first 360 degrees crank rotation (here, as an example, based on the piston located in bottom dead center), in which the reciprocating internal combustion engine operates in the two-stroke process described above, ie with each 360 degree crank rotation Injection process takes place, follows one or more 360 degree crank turns, during which no injection takes place. This means that there is no injection between two successive gas changes (piston at bottom dead center). In the case of direct injection or indirect injection with internal mixture formation, this means that no air-fuel mixture is formed in the combustion chamber and only the fresh air that is injected, possibly with exhaust gas, is compressed in the movement of the piston from its bottom dead center to the top dead center. In the absence of fuel, there is then preferably no ignition in the area of top dead center. The ignition control can accordingly preferably be coupled to the injection control. In the further movement of the piston from its top dead center to the bottom dead center, the compressed gas is released again. The work done in compression is recovered here minus any possible friction losses. The next charge change then takes place after the outlet and inlet openings have been opened, in particular when compressed fresh gas is supplied. In this, the proportion of exhaust gases in the fresh charge can be further significantly reduced and / or the cylinder can be cooled.

In the following compression stroke, depending on requirements, it can be injected again (with a higher proportion of fresh air) or another compression and expansion stroke can take place without injection and combustion, which may further increase the fresh air proportion. If, between two gas changes, injection and not injection are alternately injected, this is referred to as four-stroke operation. The proportion of fresh air in the cylinder charge corresponds essentially to that of a conventional four-stroke engine. If a gas exchange is followed by an injection process and the next two gas changes are not followed by an injection process and only the next one is followed by an injection process, this is referred to as the six-stroke process, etc. (eight-stroke process ...).

In the case of indirect injection with external mixture formation (for example intake manifold injection), depending on the design, there may be a delay of one or more 360 degree crank turns. The fuel introduced into the intake manifold then leads to an air-fuel mixture which is only passed into the combustion chamber with a delay, for example only in the or a gas exchange following the injection into the intake manifold. If the injection is now stopped, it can take one or more charge changes until the fresh charge no longer has an ignitable mixture or is fuel-free and only consists of fresh air, possibly with an exhaust gas component.

The fresh air (fresh charge) is preferably compressed by means of the pump chamber. The reciprocating internal combustion engine is preferably designed in such a way that the fresh air in the pump chamber is compressed in the piston position in which the inlet opening is opened in such a way that it has a higher pressure than the air (or exhaust gas) still in the combustion chamber. This ensures that the compressed fresh air flows over into the combustion chamber and flushes it and that no exhaust gas flows into the pump chamber. Its compression ratio and thus also the pressure can be adjusted via the size of the pump chamber and / or the stroke.

In order to prevent fresh charge from flowing out of the pump chamber through the outlet opening (s) during the piston movement to its top dead center, the piston preferably has a piston skirt on the side facing away from the combustion chamber, which also opens the outlet opening (s) in the upper Piston located dead center closes. Alternatively, for example, a controlled valve is present in the outlet opening.

As an alternative to a pump chamber, the fresh charge can be compressed, for example, by a compressor or turbocharger.

The inlet opening and / or the outlet opening are preferably designed as slots which also extend at least in the direction of movement of the piston. In particular, the inlet opening is designed as a slot which extends from the pump chamber into the combustion chamber. The point in time (that is to say the piston or crankshaft position) from which a flow from the pump chamber into the combustion chamber is possible can be determined via the length of the slot.

Alternatively and / or additionally, slots can be formed in the piston which, in cooperation with the slots, allow a flow into and out of the combustion chamber.

In addition, one or more valves can optionally be formed in the cylinder wall or the head wall of the cylinder formed by the cylinder head, which can preferably connect the combustion chamber to the environment even when the piston is in top dead center.

The valves can be opened electronically, for example, if there is no injection after the gas exchange or if there is only fresh air, possibly with exhaust gas, in the combustion chamber, so that the fresh air present in the combustion chamber in the movement of the piston from its bottom dead center to the top dead center is unimportant Compression is expelled into the environment and then fresh air is sucked in again. In this way, the compression work can be avoided.

A double crank drive is preferably used which, thanks to the linear piston guide, enables an oil-free combustion chamber and, if necessary, also a pump chamber. This can significantly improve the quality of the exhaust gas. In particular in combination with the adjustment of the cycle process, a low-emission and powerful engine can be implemented. In addition, there is no possible lack of lubrication in the case of the construction with double crank drive due to the cylinder-axial piston guide when operating in the multi-stroke process.

The control of whether or not injection is carried out is carried out by the control device in response to a power requirement and possible other parameters such as speed, temperature, gradient, speed, speed, desired fuel consumption, etc.

A preferred embodiment of the invention is explained below with reference to the figures.

• 1 eine Hubkolbenbrennkraftmaschine nach einer ersten Ausführungsform mit im unteren Totpunkt befindlichem Kolben, und
• 2 ein Diagramm, dass einem Brennraumdruckverlauf in Bezug auf Kurbelwellendrehstellung angibt.

The figures show in

• 1 a reciprocating internal combustion engine according to a first embodiment with the piston located at bottom dead center, and
• 2 a diagram that indicates a combustion chamber pressure curve in relation to the crankshaft rotational position.

1 shows a reciprocating internal combustion engine 2 with an engine block 3 in which a cylinder 4th holding a cylinder wall 6th has, is formed. In the cylinder 4th is a piston 8th arranged movably in a movement direction Y along a movement axis.

Above the piston 8th becomes a combustion chamber 10 formed by the cylinder wall 6th , the piston 8th and one on the engine block 3 attached cylinder head 12th is limited. The cylinder head 12th is with the engine block 3 for example screwed. In the cylinder head 12th is, in a known way, a spark plug 14th used, which protrudes into the combustion chamber that with her one in the combustion chamber 10 existing air-fuel mixture can be ignited. There is also an electronically controllable injection system 15th intended. The injection system 15th has a control unit (control device) 15a on, about the one in the cylinder head 12th arranged electronically controllable injection nozzle 15b via a control line 15c is controllable. The injector 15b is further via a high pressure line 15d with a high pressure pump 15e connected. Several injection nozzles can optionally be provided.

On the cylinder head 12th opposite end of the engine block 4th is a pump chamber housing 16 provided which with the cylinder head 12th for example is screwed. Below the piston 8th thus becomes a pump room 18th formed, the (depending on the position of the piston 8th ) from the cylinder wall 6th , the piston 8th and the pump chamber housing 16 is limited. The volume of the pumping chamber 28 changes in the movement of the piston 8th opposite to that of the combustion chamber 10 .

The piston 8th points to the the combustion chamber 10 remote side an in 1 not shown receptacle for a piston rod 20th on. The piston rod 20th is about an in 1 Fastening means, not shown, preferably rotationally and longitudinally fixed, preferably rigid, on the piston 8th attached. The piston rod 20th extends along the axis of movement of the piston 8th through the pump room 18th and a wall 22nd who have favourited the pumping room 18th from a double crank operation 24 separates. The piston rod 20th is by means of a sealant 26th , for example an O-ring seal, against the wall 22nd sealed.

Below the pump room 18th is a crankcase 28 for the double crank drive 24 intended. The double crank drive 24 know two cranks 30th each with a crank disc 32 and a crankshaft 34 have on which the crank disk 32 is rotatably mounted. The crank disks 32 lie in a plane which is parallel to the plane in which the axis of movement of the piston 8th lies. The crankshafts 34 are than from the crank discs 32 in a direction opposite to the piston rod 20th protruding bearing journals are formed and are in the crankcase 28 stored. The shaft axes of the crankshafts 34 are perpendicular to the direction of movement of the piston 8th and arranged symmetrically with respect to a plane of symmetry in which the axis of movement of the piston 8th lies. The essentially identical crank disks 32 each have an external toothing and are arranged in such a way that they are interlocked with one another in the area of the above-mentioned plane of symmetry and mesh with one another. Each of the crank disks 32 has a connecting rod pin (symmetrically to each other) 36 on, that of the crank disk parallel to the shaft axes on the opposite side of the crankshaft 34 protrudes.

The piston rod 20th has at its lower end a fastening area not shown in detail 38 on. At the attachment area 38 is a connecting rod connection component 40 (for example via nut) attached. The connecting rod connection component is required for assembly 40 for example in two parts, for example from two half-shells.

The connecting rod connecting component 40 furthermore has two radially with respect to the piston rod 40 opposing approaches 41 each with a through hole perpendicular to the direction of movement of the piston 8th on.

There are also two connecting rods 42 intended. Each of the connecting rods 42 has a through hole at a first end for receiving the connecting rod pin provided on the respective crank disk 36 and at a second end a through hole for receiving a connecting bolt 44 on. The connecting bolt 44 is in the through hole at the second end of the connecting rod 42 and the through hole in the above approach 42 of the connecting rod connecting component 40 used and thus connects the connecting rods 42 with the connecting rod connecting component 40 .

The piston 8th , the piston rod 20th , the connecting rod connecting component 40 who have favourited Connecting Rods 42 and the cranks 30th are designed and arranged in such a way that when one or both of the cranks are rotated 360 degrees 30th or crank disks 32 the piston undergoes a longitudinal movement between a top dead center OT and a bottom dead center BDC. For the further description it is assumed that the crank angle is at top dead center TDC of the piston 8th is defined as zero degrees. In 1 is the piston 8th shown in its bottom dead center UT.

The direction of movement of the crank discs 32 during operation of the reciprocating internal combustion engine is such that the areas of the crank disks facing the piston 32 to rotate / move towards each other. In the 1 The left crank disk rotates clockwise and the in 1 right crank disc rotates counterclockwise. By design, the crank angle required to move from the top dead center of the piston to the bottom dead center of the piston (in the range from 190 degrees to 225 degrees) is greater than the crank angle required to move from the bottom dead center of the piston to the top Dead center of the piston is needed (in the range of 135 degrees to 170 degrees). This enables a long expansion phase, which leads to improved efficiency.

Furthermore are in the cylinder wall 6th four cylinder wall flow channels are provided. In particular, the cylinder wall 6th here three cylinder wall overflow channels as cylinder wall flow channels 70a and a cylinder wall outflow channel 70b on. Each of the cylinder wall overflow channels 70a is designed as an open, trough-shaped channel that extends between an inlet opening 72a , which opens into the cylinder interior, and an overflow inlet 74a that is in the pumping room 18th opens, extends. The inlet opening 72a is with respect to the overflow inlet 74a on the double crank operation 24 remote side of the inlet opening 72a , so above, provided.

The cylinder wall outflow channel 70b extends in the cylinder wall between an outlet opening 72b , which is open into the cylinder interior, and an outlet 74b that is in an exhaust system 75 is open.

The cylinder wall overflow channels used for overflow 70a can also be referred to as overflow channels or slots, the cylinder wall outflow channel used for outflow 70b can also be referred to as an outflow channel.

The reciprocating internal combustion engine also has 2 an inlet valve 83 (in 1 not representative of the piston position shown in the open position), through which a gas (fresh air) from the environment or upstream intake tract sections (eg air filter) into the pump chamber 18th can flow in. In the present embodiment, the intake valve is 83 as a check valve or flutter valve formed in a side wall of the pump chamber housing 16 is arranged. It is designed in such a way that fresh air is directed towards the pump chamber 18th can flow in but not flow out.

In the present embodiment, the internal combustion engine is designed, for example, with a cylinder volume of 85ccm, a bore diameter of 60mm, a stroke s of 30mm, an s / D ratio (= stroke-bore ratio) of 0.5. Furthermore, the BDC is reached at a crank angle of 215 degrees.

The individual components are made of conventional materials, such as metal alloys, carbon, plastics, etc.

Certain movement positions of the piston are exemplified below 8th in its movement between its top dead center and its bottom dead center, and back, explained.

As stated above, shows 1 the reciprocating internal combustion engine with the piston at bottom dead center 8th . The piston crown is in this position (the upper part of the piston 8th or the upper edge of the sealing side wall area) below the upper edges of the cylinder wall overflow channels 70a and the cylinder wall outflow channel 70b . This creates the cylinder wall flow channels 70a , 70b released by the piston and opened into the combustion chamber. A charge exchange can thus take place.

In the movement of the piston 8th upwards towards the top dead center are the inlet openings first 72a and then the outlet opening 72b overrun by the piston and thus separated from the combustion chamber. With the piston in top dead center 8th is the outlet opening 72b from the piston skirt 76 locked. This ensures that the pump chamber 18th is not connected to the environment. The cylinder wall overflow channels 70a , especially the inlet ports 72a , are to the pumping room 18th open due to the lack of a piston skirt in this area. But this does not matter, since the cylinder wall overflow channels 70a from the pump room anyway 18th go out.

An outflow of gas from the combustion chamber 10 in the exhaust system 75 (Outlet opens) is made possible when the piston moves down the outlet opening 72b to the combustion chamber 10 releases, so it is below it. The inlet openings 72a are not yet released at this moment. The leakage of gas from the combustion chamber 10 is thus made possible before gas flows in via the overflow channels 70a is made possible.

Then also the inlet openings 72a released and begins the phase in which both the inlet ports 72a as well as the outlet opening 72b to the combustion chamber 10 to be exposed. In this phase, a charge exchange can take place, ie the gas compressed in the pump chamber can flow from this into the combustion chamber 10 stream. This is what happens in the combustion chamber 10 located exhaust gas to the outlet opening 72b pushed out. The openings remain in the further movement of the piston 8th to its bottom dead center and back again to the same position. Then first the inlet openings 72a through the piston 8th run over and thereby opposite the combustion chamber 10 closed or separated from this and then the outlet opening 72b locked.

The operation of the reciprocating internal combustion engine 2 in the two-stroke process is as follows: in one movement of the piston 8th from the bottom dead center to the top dead center, the intake ports become first 72a the cylinder wall overflow channels 70a overrun by the piston and thereby closed and separated from the combustion chamber. This creates the pumping chamber 18th from the combustion chamber 10 Fluidically separated. For example, the cylinder wall overflow channels close 70a at a crank angle of 270 degrees, the crank angle being defined here and below as 0 degrees when the piston is at top dead center.

In the further movement of the piston 8th from bottom to top, on the one hand, there is the volume of the pump chamber 18th enlarged. Because the only opening of the pumping chamber 18th in this state the inlet valve 83 is, a negative pressure is generated, which is created by sucking in fresh air from the intake tract into the pump chamber 18th is balanced.

As the movement continues, the piston passes over it 8th also the outlet opening 72b of the cylinder wall outflow channel 70b so that this is also locked. The combustion chamber 10 is no longer connected to the exhaust system. For example, the cylinder wall outflow channel closes 70b at a crank angle of 275 degrees.

In the further movement of the piston 8th the gas in the combustion chamber is compressed and further gas is sucked into the pump chamber. The outlet opening 70b however, remains closed by the elongated piston skirt, which is an extension of the side wall downwards.

In the further movement of the piston 8th upwards, the air-fuel mixture is injected and now in the combustion clamp, just before the piston 8th reaches its top dead center, ignited (for example crank angle 355 degrees). Injection and / or ignition only after or when reaching top dead center is possible. After reaching top dead center, the piston moves 8th with expansion of the ignited gas back down in the direction of its bottom dead center. From top dead center, no more gas enters the pump chamber 18th sucked in and closes the inlet valve 83 .

In the further movement this is now the case in the pumping chamber 18th Existing gas (fresh air) compressed (charged). Conversely, the movement between the bottom dead center and the top dead center will be from the point in time at which the upper sealing edge of the piston 8th through the outlet opening 72b moved, this released again towards the combustion chamber. The outlet into the exhaust system is therefore opened and the burned gas (exhaust gas) flows out of the outlet opening 72b in the exhaust system. The outlet opening 72b opens at a crank angle that results from the geometry used at the closing angle above.

In the further movement between the bottom dead center and the top dead center are when the upper sealing edge of the piston 8th on the upper edges of the inlet openings 72a moved past, this released again towards the combustion chamber. The compressed (charged) gas in the pump room 18th then flows into the combustion chamber 10 with displacement of the exhaust gas. For example, the cylinder wall overflow channels open 70a at a crank angle that results from the geometry used at the above dwell angle. In this phase the gas exchange with purging takes place.

The piston then reaches its bottom dead center again and, as described above, moves back towards the top dead center.

When operating in the multi-stroke process, the injection of fuel described above is omitted one or more times when the piston is in the region of top dead center. Applied to the above example, this means that when the piston moves in the direction of top dead center, the fresh air that has flowed in is compressed with the residual exhaust gas that has not been flushed out by purging, and no injection and preferably no ignition takes place in the area of top dead center.

There is therefore no expansion of the gas in the combustion chamber associated with the combustion of the fuel. Instead, the compressed gas moves the piston back towards bottom dead center. The power delivered to the piston during expansion corresponds (without taking into account friction losses) essentially the compression work that was previously performed during compression by the crankshaft to move the piston in the direction of top dead center, so that the compression with subsequent expansion without Combustion is essentially lossless.

Then, just as with the above-described 360 degree rotation with injection, a charge change takes place through the inflow of fresh charge from the pump chamber 18th via the inlet port 72a into the combustion chamber 10 and corresponding flushing of the combustion chamber 10 . Because the combustion chamber 10 in this case only contains fresh air with a low proportion of exhaust gas, the exhaust gas proportion is preferably further reduced in the purging that is now present.

In the following 360 degree rotation of the crank, either another injection can take place (four-stroke operation) or no injection can occur again (six-stroke operation).

The control unit controls whether or not injection takes place 15a in response to a power requirement (accelerator pedal position) and possible other parameters such as temperature, incline, speed, speed, desired fuel consumption, desired operating mode, etc.

2 shows a diagram showing the internal pressure curves (bar, Y-axis) in the combustion chamber over the crank rotation (crank angle, X-axis) and thus piston movement. In particular, the solid line shows the pressure curve in four-stroke operation and the dashed line shows the pressure curve in two-stroke operation. As can be seen, in four-stroke operation the 360 degree crank rotation without injection in TDC 2 shows no further pressure increase due to the combustion of the fuel. In the combustion stroke, however, the pressure in four-stroke operation increases to higher values than in two-stroke operation due to the better purging.

It is explicitly emphasized that all features disclosed in the description and / or the claims are viewed as separate and independent of one another for the purpose of the original disclosure as well as for the purpose of restricting the claimed invention, regardless of the combinations of features in the embodiments and / or the claims should. It is explicitly stated that all range specifications or specifications of groups of units disclose every possible intermediate value or subgroup of units for the purpose of the original disclosure as well as for the purpose of restricting the claimed invention, in particular also as a limit of a range specification.

List of reference symbols

2

Reciprocating internal combustion engine

3

Engine block

4th

cylinder

6th

Cylinder wall

8th

piston

10

Combustion chamber

12th

Cylinder head

14th

spark plug

15th

Injection system

15a

Control device

15b

Injectors

15c

Control line

15d

High pressure line

15e

high pressure pump

16

Pump chamber housing

18th

Pumping room

20th

Piston rod

22nd

wall

24

Double crank drive

26th

sealant

28

Crankcase

30th

crank

32

Crank disc

34

crankshaft

36

Connecting rod pin

38

Attachment area

40

Connecting rod connecting component

41

approach

42

Connecting rod

44

Connecting bolt

70a

Cylinder wall transfer channel

70b

Cylinder wall outflow channel

72a

Inlet opening

72b

Outlet opening

74a

Overflow inlet

74b

Outlet

75

Exhaust system

76

Piston skirt

83

Inlet valve

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 299182 A1 [0003]

Claims (10)

Reciprocating internal combustion engine (2) with at least one cylinder (4) with a cylinder wall (6), a piston (8) which is movable in the cylinder (6) along a movement axis between a top dead center and a bottom dead center, at least a part of the cylinder wall (6) and the piston (8) above the piston (8) Combustion chamber (10) is limited, in which a mixture of air and fuel is combustible with the generation of an expansion of a fuel gas, a piston rod (20) attached to or formed on the piston (8) on the side of the piston (8) facing away from the combustion chamber (10), a crankshaft drive (24) with a crankshaft (34) to which the piston (8) is coupled in such a way that the piston (8) moves from top dead center (TDC) to bottom dead center (BDC) when the crankshaft rotates through 360 degrees crank angle ) and is moved back to top dead center (TDC), and an injection system (15) electronically controlled by means of a control device (15a) for introducing fuel into the combustion chamber (10) or an inlet duct, in the In the cylinder wall (6) at least one inlet opening (72a) into the combustion chamber (10) and at least one outlet opening (72b) from the combustion chamber (10) are provided, which in the movement of the piston (8) from the top dead center to the lower Dead center are released by the piston (8) for gas exchange, the control device (15a) is designed in such a way that the reciprocating internal combustion engine (2) is optionally in a two-stroke process, in which at least once a 360 degree crank rotation is injected, or in a multi-stroke process, in which between two 360 degree crank rotations, each of which at least once is injected, with a 360 degree crank rotation or several 360 degree crank rotations in succession, no injection takes place, can be operated. Reciprocating internal combustion engine (2) according to Claim 1 , in which when operating in the multi-stroke process and when injecting directly or indirectly into the combustion chamber with each of the 360 degree crank rotations during which no injection takes place, a compression in the movement of the piston (8) from bottom dead center to top dead center and in the opposite movement of the Piston (8) from top dead center to bottom dead center an expansion corresponding to the compression takes place without combustion. Reciprocating internal combustion engine (2) according to Claim 1 or 2 , in which, regardless of whether it is operated in two-stroke or multi-stroke mode, a charge change takes place every 360 degrees of crank rotation. Reciprocating internal combustion engine (2) according to one of the Claims 1 to 3 , in which a pump chamber (18) is formed on the side of the piston (8) facing away from the combustion chamber (10), the volume of which changes with the movement of the piston (8) in the opposite direction to that of the combustion chamber (10) and which changes via a Valve (83) is connected to an environment, with the movement of the piston (8) from the bottom dead center to the top dead center at least partially filling the pump chamber (18) with gas and the movement of the piston from the top dead center The gas in the pump chamber (18) is at least partially compressed at the bottom dead center, the piston rod (20) extends through the pump chamber (18) along the axis of movement of the piston (8) and is sealed by a wall (22) of the pump chamber (18) ), the inlet opening (72a) is connected to the pump chamber (8) via a channel (70a). Reciprocating internal combustion engine (2) according to Claim 4 , in which the inlet opening (72a) and the outlet opening (72b) are designed such that the outlet opening (72b) is opened in the movement of the piston (8) from the top dead center to the bottom dead center in front of the inlet opening (72a) and preferably at the time of the opening of the inlet opening (72a), the pressure in the pump chamber is higher than the pressure in the combustion chamber. Reciprocating internal combustion engine according to Claim 4 or 5 , in which the inlet opening (72a) is designed as a section of an overflow control slot which is formed in the cylinder wall (6) and connects the pump chamber (18) and the combustion chamber (10) at least when the piston is in bottom dead center. Reciprocating internal combustion engine according to Claim 1 , in which a vent valve is provided in the cylinder wall and / or a head wall that closes the combustion chamber from above, which can be opened electronically controlled in a movement from the bottom dead center to the top dead center and back again when the piston moves back no combustion takes place from the top dead center to the bottom dead center. Reciprocating internal combustion engine according to one of the Claims 1 to 7th , in which the crank drive is designed as a double crank drive, which has two cranks rotating in opposite directions at the same speed, which are each connected to the piston rod via a connecting rod, so that the piston is coupled to the double crank drive in such a way that the piston is reversed when the double crank drive rotates 360 degrees crank angle from a top dead center to a lower one Dead center and back again to the top dead center. Reciprocating internal combustion engine according to one of the Claims 1 to 8th , which is designed without a valve drive. Method for operating a reciprocating internal combustion engine, the gas exchange of which takes place in the combustion chamber via openings in the cylinder wall which can be closed by the piston, with the following steps in a two-stroke operating mode, starting and stopping an injection process of fuel into the combustion chamber every 360 degrees of crank rotation, in a multi-stroke operating mode, starting and ending an injection process every second, third or fourth 360 degree crank rotation, and Switching between the two-stroke mode and the multi-stroke mode.

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