EP2270318A1 - Cylinder assembly for a longitudinally scavenged piston combustion engine - Google Patents

Abstract

The invention relates to a cylinder arrangement (1) for a longitudinally flushed reciprocating piston internal combustion engine, in particular for a slow-running, longitudinally flushed, two-stroke large diesel engine, comprising a cylinder (2) with a combustion chamber region (21) and an inlet region (22). A piston (3) can be installed to move back and forth along a cylinder axis (Z) between an upper dead center (TDC) and a lower dead center (UT) in the cylinder (2), a purge air inlet (4) for introducing the cylinder (2) of purge air (41) is provided in the combustion chamber area (21). According to the invention, a hollow closure element (5) suitable for receiving the piston (3) is provided in the inlet region (22) of the cylinder (2), which between an inlet position (E) and a closed position (S) along the cylinder axis (Z) - And is arranged to be movable such that the purge air inlet (4) is open in the inlet position (E) of the closure element (5) and is closed in the closed position (S) of the closure element (5).

Description

The invention relates to a cylinder arrangement for a longitudinally purged reciprocating internal combustion engine, in particular for a slow-running longitudinally purged two-stroke large diesel engine according to the preamble of independent claim 1.

Large diesel engines are often used as drive units for ships or in stationary operation, eg for driving large generators for generating electrical energy. The engines usually run for long periods in continuous operation, which places high demands on the reliability and availability. Therefore, for the operator in particular long maintenance intervals, low wear and an economical handling of fuels and supplies are central criteria for the operation of the machines. Among other things, the piston running behavior of such large-bore slow-running diesel engines is a determining factor for the length of the maintenance intervals, the Availability and lubricant consumption also directly for the operating costs and thus for the economy. Thus, the complex problem of piston running behavior in large diesel engines is becoming increasingly important.

In large diesel engines, but not only these, the piston lubrication is performed by lubricating means in the reciprocating piston or in the cylinder wall, is applied by the lubricating oil on the tread of the cylinder wall, the friction between the piston and the tread and thus the wear of the tread and to minimize the piston rings. So today with modern engines, such as the Wärtsilä two-stroke engines, the wear of the tread at less than 0.05 mm with a service life of 1000 hours. The lubricant delivery rate is about 1.3 g / kWh and less in such engines and should not least be further reduced for cost reasons as possible, while the wear is to be minimized.

In this case, very different solutions are known as lubrication systems for lubricating the running surfaces of the cylinder, both as far as the actual execution of the lubrication devices themselves, as well as the procedures for lubrication. The corresponding solutions are well known to the skilled person in their different variants.

A central point is always the difficulty of optimizing the lubricant film on the cylinder surface as locally as possible

For example, in the CH 613 495 discloses a cylinder apparatus for a reciprocating internal combustion engine, which detects abnormal friction conditions of the piston rings by means of a temperature or vibration sensor to prevent the seizure of piston rings during operation and when such disturbances occur, the amount of lubricating oil discharged from a particular lubrication point is increased. The EP 0 652 426 shows a method in which by cyclically measuring the temperature in the cylinder wall, the occurrence of scuffing or Verschleissfressen is detected on the basis of a characteristic temperature profile and a corresponding damage by an automatic power reduction and / or by increasing the supply of lubricant is counteracted. Another known method for early detection of critical operating conditions of an internal combustion engine is in the EP 1 006 271 shown ultrasonic method in which by means of arranged in a cylinder ultrasonic transducer of the mating partner is subjected to ultrasonic signals and the reflected echo signals is used to determine the state of the mating partner.

If, for example, the occurrence of piston seizure or scuffing is detected in a device known from the prior art, then the lubricant quantity is increased for this cylinder until the detected abnormal operating state disappears again and the quantity of lubricant supplied to this cylinder per unit time again can be reduced.

In order to solve the above-described complex problems associated with cylinder lubrication, numerous approaches have been proposed in the prior art, some of which relate to each other and relate to the manner of applying the lubricant, to control and regulate the amount of lubricant, optimized piston designs, in particular The optimization of individual piston rings or entire piston ring packages concern or for example try on the chemical composition of the lubricating oil or the fuel to optimize the lubrication system and thus the piston behavior.

However, all these measures run more or less futile when the tread on the cylinder wall of the cylinder liner, with which the piston is in frictional contact with the piston ring packings in its reciprocating motion in the operating state, is not or only insufficiently suitable, a reliable lubricant film to train on the tread.

Therefore, the production of the tread on a cylinder wall of a cylinder liner is a critical point, the attention of which has rightly become increasingly important.

The usually used cylinder liners are generally produced by a well-known casting method, whereby initially a cylinder liner blank is provided. The casting material is suitably enriched with hard materials or the casting and cooling process is influenced in a conventional manner such that during casting and / or cooling of the cylinder liner blank in the cast base material more or less extensive areas of hard phases, the Example may include per se known carbides or other known hard phases, educate or excreted. These hard phases form a more or less irregular distribution or matrix in the cast base material, resulting in an advantageous combination of relatively soft cast base material and hard phases. The relatively soft cast base material ensures, for example, among other things, a certain mechanical elasticity and fatigue strength of the cylinder liner, so that it can withstand the enormous temperature and pressure fluctuation loads in the operating state of the internal combustion engine. The hard phases, however, give the cylinder wall or the running surface of the cylinder a sufficiently high hardness, but not only, against excessive wear due to friction between the piston and the cylinder surface. The different manufacturing processes of this type of cylinder liners and their properties are well known to those skilled in the art and therefore need not be further explained here.

An inner wall of the cylinder liner blank, which will later form the running surface for the piston on the cylinder wall, is then usually processed in several complex steps. First, in a rotary machining step in the cylinder wall in the circumferential direction, a channel-like coarse structure is created with circumferential channels, which coarse structure extending helically along the cylinder axis in the cylinder wall of the cylinder liner. Subsequently, the cylinder surface can be pre-honed and finish-honed and possibly subjected to a suitable finishing process, so that the tread receives a finer structure.

To optimize the cylinder surfaces of cylinder liners, the applicant has recently in the EP 09 161 118 a completely proposed method for producing a running surface on a cylinder wall of a cylinder liner of a reciprocating internal combustion engine, in which a capillary-like fine structure is machined helically along the cylinder axis in the cylinder wall of the cylinder liner. Cross-connections between the circumferential capillaries of the capillary-like fine structure are thus created in a transverse processing method such that the capillary-like fine structure is substantially retained.

The fact that the circulating capillaries gemäs in the application of the transverse processing method EP 09 161 118 on the one hand a breaking of the hard phases, both during the execution of the machining process itself, as well as during the subsequent operation of the cylinder liner is largely prevented, and at the same time the oil retention volume of the tread is optimized, the distribution of Lubricating oil film on the cylinder surface massively improved, and it is a sufficient momentum in terms of direction and flow rate of movement of the lubricating oil when flowing on the tread in the operating condition of the cylinder liner guaranteed.

However, all these measures to improve the lubrication and the piston running leave a problem unaffected, the design and thus inevitably occurs in the previously known longitudinally flushed internal combustion engines. As is well known to those skilled in the known longitudinally-flushed two-stroke engines, the fresh air, often referred to as scavenging air introduced at the bottom of the cylinder via scavenging air usually in the form of scavenging slots in the combustion chamber of the cylinder, while the piston is in the vicinity of his is bottom dead center and clears the path for the fresh air into the combustion chamber of the cylinder.

The scavenging ports, through which the fresh air is blown, for example, from a turbocharger into the cylinder under a predetermined pressure, per se do not allow uniform formation of the lubricating oil film on the inner surface of the cylinder in the region of the scavenging slots, since the scavenging ports have openings in the cylinder wall of the cylinder and therefore interrupt the lubricating oil film. The negative influence of the scavenging slots on the formation of the lubricating oil film on the running surface of the cylinder is even below and far above, so even outside the cylinder portion in which the scavenging slots are formed, clearly pronounced. That is, due to the purging slits disturbance of the lubricating oil film on the cylinder surface continues in areas far away from the scavenging and thus far away from the scavenging the piston running behavior and the lubrication between piston or piston rings and cylinder wall significantly negative.

Another negative side effect of the scavenging slots results from their interaction with the piston rings as they pass through the scavenging slots as they move near bottom dead center. Since the piston rings must have a certain mechanical radial prestress so that they can cooperate more or less sealingly with the cylinder wall, these are not formed as completely closed rings, but the piston rings are rather formed as open rings with a gap, so that a radially to externally directed clamping force is created, which presses the piston ring sealingly against the cylinder wall. Under unfavorable conditions, the margins at the gap of the piston ring can be partially pressed into the flushing slots due to the radially outward acting tension of the piston ring, whereby they can get caught on the boundaries of the scavenging slots, resulting in dangerous scratches or grooves on the cylinder or on the cylinder wall near the scavenging slots. In the worst case, this can lead to a seizure and destruction of the cylinder and / or the piston, which can lead to dangerous situations especially in a ship on the high seas.

In addition, a considerable amount of lubricating oil is lost through the scavenging slots when passing the piston ring package. Namely, a certain amount of lubricating oil is always stored in the piston ring package which accumulates in the piston ring package during the movement of the piston in the cylinder and is also under an increased gas pressure, which is essentially built up during the combustion process in the piston ring package and stored therein. If the piston ring package then passes through the scavenging slots, the overpressure stored in the piston ring pack discharges abruptly via the scavenging slots into the receiver chamber and at the same time conveys most of the lubricating oil also stored in the piston ring package through the scavenging slots into the receiver chamber. On the one hand leads to the loss of relatively expensive lubricating oil and on the other hand leads to unnecessary pollution of the Receiver space. In addition, the lubricating oil is no longer available for lubrication during further movement of the piston.

The object of the invention is therefore to provide a novel cylinder arrangement for a longitudinally-flushed reciprocating internal combustion engine, in particular for a slow-running two-stroke large diesel engine, which are known from the prior art problems, which are substantially determined in particular by the scavenging slots in the lower region of the known cylinder assembly , avoids.

The objects of the invention solving these objects are characterized by the features of independent claim 1.

The dependent claims relate to particularly advantageous embodiments of the invention.

The invention thus relates to a cylinder arrangement for a longitudinally-flushed reciprocating internal combustion engine, in particular for a slow-running longitudinally-flushed two-stroke large diesel engine, comprising a cylinder with a combustion chamber region and an inlet region. In the cylinder, a piston along a cylinder axis between a top dead center and a bottom dead center reciprocally installable, wherein on the cylinder a scavenging air inlet for introducing scavenging air is provided in the combustion chamber region. According to the invention, a hollow closure element suitable for receiving the piston is provided in the inlet region of the cylinder so that it can be moved back and forth between the inlet position and a closing position such that the scavenging air inlet is open in the inlet position of the closure element and in the closing position of the closure element Closing element is closed.

Characterized in that in the inlet region of the cylinder, a suitable for receiving the piston, hollow closure element is provided between an inlet position and a closing position such along the cylinder axis reciprocally disposed and movable that the scavenging air inlet in the inlet position of the closure element is open and in the Closing position of the closure element is closed, the piston is no longer in its movement in the vicinity of the bottom dead center with the scavenging air, in particular so with the scavenging slots in direct contact.

That is, the piston always "sees" even during its movement near the bottom dead center a smooth cylinder wall or tread, since the piston is introduced in the vicinity of the bottom dead center in the hollow configured closure element, which in the circumferential direction an inner, closed and forms smooth surface without any radial openings.

Characterized in that in the inventive cylinder arrangement of the piston skirt and thus the piston ring package does not interact directly with an air inlet opening in the lower region of the cylinder through which air inlet opening fresh air is blown, for example, from a turbocharger in the cylinder under a predetermined pressure, there are various advantages.

During the rinsing-closing process known from the prior art, that is to say when the piston upper part closes the rinsing slots, the piston upper part is exposed to an oil mist. This oil mist results from cylinder oil which is blown in advance, for example, during the downward movement of the piston in the direction of bottom dead center by the pressure discharge from the ring pack of the piston rings in the piston bottom. The aforementioned oil mist is then in the form of deposits (Ölkoks) on the piston upper part which can lead to the well-known harmful "liner polishing" and in the worst case even to feeding. In a two-part liner according to the present invention, the upper piston part is also protected during the closing process and thus the harmful Ölkoksablagerungen be avoided on the piston upper part.

A further advantage arises from the fact that, in the cylinder arrangement according to the invention, the piston skirt and thus the piston ring assembly do not interact directly with an air inlet opening in the lower region of the cylinder, through which air inlet opening fresh air is blown, for example, from a turbocharger into the cylinder under a predetermined pressure a completely uniform formation of the lubricating oil film on the inner surface of the cylinder also in the region of the air inlet, if available also in the scavenging slots possible, since the lubricating oil film is formed on the inner smooth peripheral surface of the closure element, with which cooperates the piston skirt. The lubricating oil film can form completely uniformly from the upper part of the cylinder into the closure element. The lubricating oil film on the cylinder wall is thus no longer interrupted by the air inlet openings, since the lubricating oil film in the region of the air inlet openings is no longer formed on the cylinder wall itself, but on the smooth inner peripheral surface of the closure element. A negative influence of the air inlet openings, e.g. a negative influence by the scavenging slots on the formation of the lubricating oil film is therefore excluded below and above the air inlet.

Thus, a harmful interaction of the air inlet openings is excluded with the piston rings, as they no longer interact with their movement in the vicinity of the bottom dead center with the cylinder wall and the air inlet openings as such, but with the smooth inner peripheral surface of the closure element. Thus, the Edges on the gap of the piston ring due to the radially outwardly acting tension of the piston ring also no longer pressed into the air inlet openings, so that they can not get caught at the boundaries of the scavenging slots, so that the inventive cylinder arrangement, the dangerous scratches or grooves on the cylinder or can no longer occur on the cylinder wall.

Also, no lubricating oil is lost over the scavenging slots, since the piston ring package with the air inlet openings no longer comes into direct contact, so that the lubricating oil remains in the piston ring package and is available for further lubrication. As a result, a considerable amount of lubricating oil can ultimately be saved, the lubrication between the piston and cylinder is massively improved, in particular in the lower region of the cylinder in the vicinity of the bottom dead center and the receiver chamber is no longer contaminated by lubricating oil from the piston ring package.

A further advantage of the cylinder arrangement according to the invention in a special exemplary embodiment is additionally that the purging air does not constantly bear against the underside of the piston, as is the case with the cylinder arrangements known from the prior art, provided a stuffing box is provided at the bottom of the closure element. through which the piston rod is sealingly passed through the bottom of the closure element. In this particular exemplary embodiment of a cylinder arrangement according to the invention, the stuffing box on the closing element closes the underside of the cylinder outwards after introduction of the scavenging air into the combustion chamber, for example against the receiver space, which is supplied with purging air by a turbocharger. As a result, firstly, a pressure loss in the cylinder space below the piston is avoided, so that correspondingly more power is available for the charging of the remaining cylinders with purging air. On the other hand, in the expansion stroke, the piston does not have to be against the one supplied by the turbocharger Purge air pressure work because the closure element, the scavenging air openings are only released when the piston has reached bottom dead center. Through these effects can be additionally saved fuel, which plays an increasingly important role, especially for economic reasons, but also for reasons of environmental protection.

In a preferred embodiment of a cylinder arrangement according to the invention, a closing element is provided in such a way that the closing element can be displaced from the inlet position into the closing position by the closing element. The closing element may be a compression spring element, preferably a mechanical compression spring element, e.g. be in the form of a compression spring, which may be formed in particular as a spiral spring.

In another variant, however, compression spring element can also be a pneumatic or hydraulic pressure spring element, in particular an air pressure spring.

When using a compression spring element, the closure element is pushed by the piston in its movement in the direction of bottom dead center against a mechanical pressure of the compression spring element from the closed position to the inlet position, so that a scavenging air is released and scavenging air via a scavenging air into the combustion chamber of the Cylinder can get. When the piston continues its movement after passing through the bottom dead center in the direction of top dead center, the closure element is pushed back into the closed position by the compression spring element and the purging air opening is closed again by the closure element.

In another embodiment variant, the closing element may also be a tension spring element, wherein the tension spring element may be, for example, a mechanical tension spring element, in particular a tension spring, or else a pneumatic or hydraulic tension spring element, in particular an air tension spring.

When using a tension spring element, the closure element is pushed by the piston in its movement in the direction of bottom dead center against a mechanical train of Zugfederelements from the closed position to the inlet position, so that the scavenging air is released and scavenging air through the scavenging air in the combustion chamber of the Cylinder can get. If the piston continues its movement after passing through the bottom dead center in the direction of top dead center, the closure element is pulled back by the tension spring element in the closed position and the scavenging air opening closed by the closure element again. In the case of a pneumatic or hydraulic Zugfederelements, for example, during the movement of the closure element from the closed position into the inlet position in a pneumatic or hydraulic piston, a negative pressure can be generated, with the aid of the closure element is pulled back into the closed position.

In particular, the closing element can be an actively controlled closing element, in particular when the closing element is a pneumatic or hydraulic compression spring element or tension spring element. By way of example, a hydraulic or pneumatic piston, that is to say a closing piston which can be acted upon by a fluid, is suitably in operative connection with the closing element and actively moves the closing element out of the closed position into the inlet position and / or actively out of the inlet position into the closing position. For this purpose, the hydraulic or For example, pneumatic pistons may be connected to a hydraulic or pneumatic control device that appropriately applies a pneumatic or hydraulic fluid, such as air or oil, to the piston so that the pneumatic or hydraulic piston actively brings the closing element into a predeterminable position. Advantageously, different sensors can be provided, for example position sensors for determining the position of the piston, so that the control device can optimally control the closing element in dependence on suitably selected operating parameters.

In a specific exemplary embodiment, the cylinder with combustion chamber region and inlet region is designed in one piece, wherein the closure element is preferably provided in a cylindrical recess in the inlet region of the cylinder. It can optionally be formed by scavenging slots at the inlet area, which are covered in the closed position by the closure element, so that the piston or the piston ring package does not come into frictional contact with the scavenging slots in its movement towards bottom dead center, because the piston from the closing element taken up and enclosed in the circumferential direction ..

Additionally or alternatively, a guide device for influencing a purge air flow of the purge air (41) may be provided at the inlet region of the cylinder, wherein the guide device may in particular be a controllable guide device, so that the purge air flow can be influenced as a function of a purge air parameter. By providing a guide device, the scavenging air inlet into the cylinder can be optimized, wherein when using a controllable guide, for example by a suitable rotation of the baffles, preferably depending on certain operating parameters of the internal combustion engine, the scavenging air in the cylinder can be optimally controlled and / or regulated ,

Fig. 1

eine bekannte Zylinderanordnung mit Spülschlitzen im Längsschnitt;

Fig. 2a

schematische Darstellung einer ersten erfindungsgemässen Zylinderanordnung mit Druckfederelement und Verschlusselement in der Schliessposition;

Fig. 2b

die Zylinderanordnung der Fig. 2a mit Verschlusselement in der Einlassposition;

Fig. 3

ein zweites Ausführungsbeispiel einer erfindungsgemässen Zylinderanordnung mit einem Zugfederelement;

Fig. 4

ein drittes Ausführungsbeispiel mit einer einteiligen Zylinderanordnung und Spühlschlitzen;

Fig. 5

ein Ausführungsbeispiel mit Leiteinrichtung zur Beeinflussung des Spülluftstroms .

The invention will be explained in more detail below with reference to the schematic drawing. Show it:

Fig. 1

a known cylinder arrangement with scavenging slots in longitudinal section;

Fig. 2a

schematic representation of a first inventive cylinder arrangement with compression spring element and closure element in the closed position;

Fig. 2b

the cylinder arrangement of Fig. 2a with closure element in the inlet position;

Fig. 3

A second embodiment of an inventive cylinder assembly with a tension spring element;

Fig. 4

a third embodiment with a one-piece cylinder assembly and scavenging slots;

Fig. 5

an embodiment with guide for influencing the purge air flow.

Fig. 1 shows in a schematic representation partially in section a cylinder assembly 1 'with cylinder liner 2', piston 3 'and fresh air supply system 400'.

The cylinder assembly 1 'of Fig. 1 is a typical arrangement well known for prior art longitudinally scavenged two-stroke large diesel engines. For a better distinction of the known cylinder arrangement, the corresponding reference numerals are provided with an apostrophe, while the reference numerals to features according to the invention cylinder arrangements wear no apostrophe.

The arrangement comprises a cylinder 2 ', which is also referred to as a cylinder liner 2', in which a piston 3 'along a cylinder wall of the cylinder 2' is arranged back and forth movable. The piston 3 'comprises a piston ring packing 31', which is shown here schematically with only two piston rings.

The combustion chamber 200 ', which is located in the combustion chamber region 21' of the cylinder 2 ', is delimited at the top by a cylinder cover with an injection nozzle and exhaust valve.

The piston 3 ', which reciprocates in the operating state of the large diesel engine between the top dead center OT' and the bottom dead center UT ', via the piston rod 8' with a in Fig. 1 not shown crosshead, from which the reciprocating movement of the piston 3 'is transmitted to the crankshaft, also not shown, of the machine. The piston rod 8 'is guided through the receiver space 401', which adjoins the inlet area 22 'of the cylinder liner 2' below, and the stuffing box 402 ', which seals the receiver space 401' against the crankshaft space below, so that no fresh air 41 ', symbolized by the arrow 41', which supplies a likewise not shown turbocharger under a high pressure, for example, under a pressure of four bar in the receiver chamber 401 ', from the receiver room 401' in the underlying crankshaft space 9 'can pass.

Again Fig. 1 can be seen and is generally known, is in the receiver chamber 401 'always generated by the turbocharger gas pressure of the fresh air 41', which thus always by design rests on the piston bottom of the piston 3 '.

After a combustion process initiated in the combustion chamber 200 'when the piston 3' is very close to the top dead center OT ', the piston 3' moves toward the bottom dead center UT 'due to the combustion pressure built up in the combustion chamber 200'. wherein, when the piston surface is below the scavenging air opening 4 'with scavenging slots 221', scavenging air 41 'can reach the combustion space 200' via the scavenging slots 4 'from the receiver space 401', so that they can be burned in the combustion space 200 'for the next combustion process. is available.

On its way from top dead center OT 'to bottom dead center UT' and back, the piston must inevitably pass through the scavenging ports 4 'in the inlet region 22', which has the negative consequences already described in detail, which need not be repeated here in detail.

In Fig. 2a is a first inventive cylinder arrangement, which is hereinafter referred to in its entirety by the reference numeral 1, schematically shown with compression spring element 6, 61 and closure element 5 in the closed position S.

The arrangement comprises in a conventional manner a cylinder 2, which is also referred to as a cylinder liner 2, in particular in the case of two-stroke large diesel engines, in which a piston 3 along a cylinder wall of the cylinder 2 is arranged back and forth movable. The piston 3 usually comprises a piston ring packing with a plurality of piston rings, which is not explicitly shown here for reasons of clarity.

The combustion chamber 200, which is located in the combustion chamber region 21 of the cylinder 2, is delimited at the top by a cylinder cover with an injection nozzle and an outlet valve.

The piston 3, which reciprocates in the operating state of the large diesel engine between the top dead center OT and the bottom dead center UT, is via a piston rod 8 with a in Fig. 1 not shown crosshead, from which the reciprocating movement of the piston 3 is transmitted to the crankshaft, also not shown, of the machine. The piston rod 8 is in ans known manner through the receiver chamber 401, which adjoins the bottom as shown in the inlet portion 22 of the cylinder liner 2, and the stuffing box 402 which seals the receiver chamber 401 against the underlying crankshaft space, so that no fresh air 41, symbolized by the arrow 41, which supplies a turbocharger also not shown under a high pressure, for example, under a pressure of four bar in the receiver chamber 401, from the receiver room 401 can get into the underlying crankshaft space 9.

Again Fig. 1 can also be found in the inventive cylinder assembly 1 in the receiver chamber 401 always the gas pressure of the fresh air 41 generated by the turbocharger, which thus in the example of Fig. 2a always applied to the piston bottom of the piston 3.

Provided at an inlet region 22 of the cylinder 2 is a hollow closure element 5 suitable for receiving the piston 3, which is arranged so as to be reciprocatable along an axis position Z between an inlet position E and a closing position S such that the scavenging air inlet 4 is in the inlet position E of the closure element 5 is open and is closed in the closed position S of the closure element 5. In Fig. 2a the piston 3 is still in the combustion chamber region 21 of the cylinder 2 and has not yet reached the closure element 5 in the inlet region 22. Therefore, the closure element 5 is according to Fig. 2a even in the closed position S, in which it is held stable by the compression spring element 6, 61. The scavenging air inlet 4 is therefore still closed.

After a combustion process which is initiated in the combustion chamber 200 when the piston 3 is very close to the top dead center OT, the piston 3 moves in the direction of the bottom dead center UT due to the combustion pressure built up in the combustion chamber 200. When the piston 3 reaches the inlet portion 22 as it moves toward the bottom dead center UT, the piston 3 is gradually received by the hollow shutter member 5 and circumferentially enclosed by the shutter member 5. On its further movement in the direction of bottom dead center UT, the piston 3 then takes the closure element 5 with it and is moved by the piston 3 as in FIG Fig. 2b shown moved to the inlet position E.

Fig. 2b shows the closure element in its inlet position E, which corresponds to the bottom dead center position UT of the piston. In the inlet position E, the scavenging air inlet 4 is released so that scavenging air 41 can flow out of the receiver chamber 401 into the combustion chamber 200. When the piston 3 then moves back toward the top dead center OT, the closure element 5 by the closing element 6, 61, in the example of Fig. 2a and 2 B a compression spring is gradually returned to the closed position Fig. 2b pushed back.

The Fig. 3 schematically shows a second embodiment of an inventive cylinder assembly with a tension spring element 62. The example of Fig. 3 differs from the one according to Fig. 2a respectively. Fig. 2b merely in that the closure element 5 is returned by means of a closing element 6 in its closed position S back, which is designed as a mechanical tension spring element 62 in the form of a tension spring 62. That is, the tension spring element 62 pulls the closure element 5 from the inlet position E, in which the scavenging air inlet for introducing scavenging air 41 is opened into the combustion chamber 200, back to the closed position S, when the piston 3 from the bottom dead center UT again in the direction of top dead center OT moves. at Fig. 3 is the scavenging air 4 only partially opened, because the piston 3 has already passed through the bottom dead center position UT and is already in the direction of OT in the compression stroke.

In Fig. 4 is a third embodiment with a one-piece cylinder assembly and scavenging slots 221 shown schematically. In contrast to the embodiments of the Fig. 2a and Fig. 2b respectively. Fig. 3 the closure element 5 is not formed by the lower part of the cylinder 2. Rather, the cylinder 2 is designed in one piece, wherein in the inlet region 22 of the cylinder 2 a cylindrical recess 220 formed in the circumferential direction of the cylinder 2 is provided, into which the closure element 5 is fitted such that an inner diameter of the closure element 5 is substantially identical to an inner diameter of the cylinder 2, so that the piston 3 coming from top dead center OT forth can slide smoothly and without impact into the closure element 5 and this can carry on its further path to bottom dead center UT from the closed position S in the inlet position E.

In this embodiment, but need not, as in Fig. 4 can be seen at the scavenging air inlet 4 also known per se scavenging slots 221 may be provided. In the closing position S, the scavenging slots 221 are covered by the closure element 5. Since the piston 3 is enclosed by the closure element 5 in the circumferential direction before it passes through the inlet region 22 with the scavenging slots 221, the piston 3 does not come into contact with the cylinder wall interrupted by the scavenging slots 221 in this exemplary embodiment, so that this embodiment too is all above having described advantages of the invention.

The scavenging slots 221 can serve to give the scavenging air 41 a suitable flow form in a manner known per se so that the combustion chamber 200 is rinsed better and more effectively by the scavenging air 41.

In Fig. 4 are provided as closing elements 6 actively controllable, acted upon by a fluid closing piston 63. The closing piston 63 are, for example pneumatically operated with air or hydraulically with oil and are connected in a conventional manner with an external fluid circuit, not shown, with pressure system, which can set the closing piston 63 in response to the position of the closing element 5 below a predetermined pressure, thereby the movement of the closing element 5 between inlet position E and closing position S can be supported, or controlled and / or regulated. It is understood that in the embodiment of the Fig. 4 Additionally or alternatively, mechanical closing elements 6, 61, 62 could be provided, as for example with reference to FIG Fig. 2a and Fig. 2b respectively. Fig. 3 described.

In Fig. 5 Finally, in a highly schematic representation and in a section perpendicular to the cylinder axis Z in the region of the receiver chamber 401, an exemplary embodiment according to the invention with a guide device 7 for influencing a purging air flow 42 into the combustion chamber 200 is shown.

The guide devices 7, which may be adjustable or non-adjustable baffles 7, for example, serve additionally or alternatively to the scavenging slots 221 to give the scavenging air flow 42 of the scavenging air 41 an even more effective flow shape, so that the combustion chamber 200 is even better and more effective Purge air 41 is rinsed.

It is understood that the embodiments described in the context of this application are to be understood as exemplary only and the invention is not limited to these examples. In particular, the described embodiments can also be advantageously combined. For example, at the same time a compression spring element and a tension spring element can be provided on one and the same cylinder arrangement, whereby movement of the closing element between the inlet position and the closing position can be controlled or regulated more precisely, for example.

Claims (15)

Cylinder arrangement for a longitudinally purged reciprocating internal combustion engine, in particular for a slow-running longitudinally purged two-stroke large diesel engine comprising a cylinder (2) with a combustion chamber region (21) and an inlet region (22), in which cylinder (2) a piston (3) along a cylinder axis ( Z) between a top dead center (TDC) and a bottom dead center (UT) reciprocally installable, and on the cylinder (2) a scavenging air inlet (4) for introducing purging air (41) is provided in the combustion chamber region (21), characterized in that in the inlet region (22) of the cylinder (2) for receiving the piston (3) suitable, hollow closure element (5) is provided which between an inlet position (E) and a closing position (S) along the cylinder axis ( Z) is arranged reciprocable that the scavenging air inlet (4) in the inlet position (E) of the closure element (5) is open and in the closed position (S) of the closure sements (5) is closed. Cylinder assembly according to claim 1, wherein a closing element (6, 61, 62, 63) is provided such that the closure element (5) through the closing element (6, 61, 62, 63) from the inlet position (E) in the closed position (S ) is displaceable. Cylinder assembly according to claim 2, wherein the closing element (6, 61, 62, 63) is a compression spring element (61). Cylinder arrangement according to claim 3, wherein the compression spring element (61) is a mechanical pressure spring element (61), in particular a compression spring (61). Cylinder arrangement according to claim 3 or 4, wherein the compression spring element (61) is a pneumatic or hydraulic pressure spring element (61), in particular an air pressure spring (61). Cylinder arrangement according to one of claims 2 to 5, wherein the closing element (6, 61, 62, 63) is a tension spring element (62). Cylinder arrangement according to claim 6, wherein the tension spring element (62) is a mechanical tension spring element (62), in particular a tension spring (62). Cylinder arrangement according to claim 6 or 7, wherein the tension spring element (62) is a pneumatic or hydraulic tension spring element (62), in particular an air-tension spring (62). Cylinder arrangement according to one of claims 2 to 8, wherein the closing element (6, 61, 62, 63) is an actively controlled closing element (6, 61, 62, 63). A cylinder arrangement according to claim 9, wherein the active controlled closing element (6, 61, 62, 63) is a closing piston (63) which can be acted upon by a fluid. Cylinder arrangement according to one of the preceding claims, wherein the cylinder (2) with combustion chamber region (21) and inlet region (22) is made in one piece. Cylinder arrangement according to claim 11, wherein the closure element (5) in a cylindrical recess (220) in the inlet region (22) of the cylinder (2) is provided. The cylinder assembly of claim 12, wherein the inlet portion (22) is formed by scavenge slots (221). Cylinder arrangement according to one of the preceding claims, wherein at the inlet region (22) of the cylinder (2) a guide means (7) for influencing a purging air flow (42) of the purging air (41) is provided. Cylinder arrangement according to claim 14, wherein the guide device (7) is a controllable guide device (7), so that the purging air flow (42) can be influenced as a function of a purging air parameter.

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