JP2013119852A - Piston and cylinder configuration for reciprocating piston combustion engine, and method of removing deposit from piston - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piston in which deposits can be removed.SOLUTION: In the piston 1 for a large two-stroke diesel engine with one cylinder liner 3, the piston is arranged in the cylinder liner to be movable back and forth in an axial direction along a piston axis (A), between a top dead center OPT and a bottom dead center of the cylinder liner. Here, a piston ring package 4 including at least one piston ring configured as an upper ring 41 closest to an upside 1011 of the piston is formed on a jacket surface of the piston, between a piston crown 101 adjacent to a combustion space VB and a piston skirt 102 away from the combustion space. A notch part 5 is provided on the jacket surface of the piston in a piston crown area, between the upper ring and the upside of the piston. A deposit on the surface of the piston is carried to the notch part by an abrasion-proof ring APR. The temporarily stored deposit is removed with lubricating oil or by scavenging.

Description

  The present application relates to the piston and cylinder arrangement of a reciprocating piston combustion engine, such as a large two-stroke diesel engine, as indicated in the preambles of the independent claims 1, 9 and 14, and further deposits from the jacket surface of the piston. It relates to a method of removing.

  In general, conventionally known pistons for reciprocating piston combustion engines, such as large two-stroke diesel engines, especially two-stroke diesel engines, which are scavenged in the longitudinal direction, are arranged in each other in their respective piston ring grooves. A plurality of piston ring packages are provided. Conventional piston ring packages typically have at least two piston rings, but depending on the size, power, or configuration of the reciprocating piston combustion engine, or depending on the demands and special operating conditions related to engine operation, May have 4 or 5 piston rings.

  In this regard, piston rings can be used to distribute and / or wipe lubricant on the working surface of the cylinder, seal the combustion space to the crankcase, or seal the receiving space in the case of a longitudinally scavenged large two-stroke diesel engine, etc. Satisfy very different functions such as

  In the case of a longitudinally scavenged large two-stroke diesel engine, a piston ring package consisting of 4 or 5 piston rings is usually used to seal the combustion space against the underside of the piston, which is directed towards the receiving space At the beginning of the scavenging phase, fresh air flows from here through the scavenging slits into the combustion space of the cylinder. The lower piston ring is loaded approximately according to the ring gap. In this regard, different types of instabilities occur between the lower piston rings, resulting in, for example, pressure fluctuations, which result in unstable piston operation. There are many piston rings because they have similar or identical functions.

  Large diesel engines are often used as ship drive units or in static operation, for example for driving large generators for generating electrical energy. In this regard, the engine usually runs in permanent operation for a considerable amount of time, which is a great demand for operational safety and availability. Thus, especially at long service intervals, low wear and economical handling of fuel and working material is a central measure when an operator operates the machine. The piston operating behavior of such large bore low operating diesel engines, in particular, is a determinant of service interval length and availability, and directly affects operating costs and efficiency through lubricant and fuel consumption. To do. The complex problem of cylinder lubricity and combustion space seals due to the piston ring package of the engine has therefore become increasingly important, especially provided by a lubrication device moving back and forth in the piston or on the cylinder wall The lubricating oil nozzle provides cylinder lubricity in large diesel engines.

  A recurring problem in combustion engine operation is the combustion residue that accumulates at most fluctuating points within the engine. In particular, in large two-stroke diesel engines that are often operated with heavy oil fuel, combustion residue is a major problem. The fuel used, i.e., heavy oil fuel, changes into many substances, resulting in all kinds of combustion residues in solid, liquid and gaseous form, and this is especially deposited in the ring groove position of the piston It is to be done. It is also deposited near the piston crown or top dead center of the cylinder.

の2ストロークエンジンでは、シリンダライナの上部に、いわゆる抗摩
耗リングが提供され、燃焼残渣の堆積物がピストンクラウンから除去されることが知られ
ている。このリングは、例えば、矩形断面を有する薄壁ソケットとして形成され、これは、通常、シリンダ自身よりも小さな内部断面を有する。除去効果は、直径収縮によって生じ、ピストンクラウンで堆積物が剥ぎ取られる。これに関して、抗摩耗リングの内径は、ピストンクラウンの直径に基づいており、具体的には、エンジン動作におけるその最大直径に基づく。従って、従来の抗摩耗リングは、内径が狭くなるように構成され、ピストンクラウンと抗摩耗リングの間のギャップは、可能な限り小さくされる。しかしながら、ピストンクラウンは、直接接する抗摩耗リングを機械的に研磨しない。 In particular, for example,

In the two-stroke engine of this type, it is known that a so-called anti-wear ring is provided at the top of the cylinder liner to remove combustion residue deposits from the piston crown. This ring is formed, for example, as a thin-walled socket with a rectangular cross section, which usually has an internal cross section that is smaller than the cylinder itself. The removal effect is caused by diameter shrinkage, and the deposit is stripped off by the piston crown. In this regard, the inner diameter of the anti-wear ring is based on the diameter of the piston crown and in particular based on its maximum diameter in engine operation. Therefore, the conventional anti-wear ring is configured to have a narrow inner diameter, and the gap between the piston crown and the anti-wear ring is made as small as possible. However, the piston crown does not mechanically polish the anti-wear ring that is in direct contact.

  Obviously, the construction of the anti-wear ring involves numerous compromises. In a cold piston crown with a low load, the clearance, which is the space between the piston crown and the anti-wear ring, is larger than the value at high load, simply due to the effect of thermal expansion. In this regard, different cylinder components such as cylinder working surfaces, pistons, in particular piston rings, piston ring grooves, and piston crowns, typically have different circumferential and longitudinal wear depending on the operating time. An additional consideration is that there is no constant diameter.

  Thus, it is clear that the anti-wear ring and the piston crown do not interact ideally under all operating conditions and do not exceed the full service life of previously known engine components.

  In this regard, the unresolved issue is that the anti-wear ring, often abbreviated as APR, does not reach the top margin of the piston ring package enough, but reaches the top ring of the piston ring package at the top dead center of the piston. Is not to. This is because otherwise, the anti-wear ring will come into contact with the upper ring, resulting in significant damage, which in the worst case will lead to damage of the upper ring or severe damage to the piston itself. . This results in cylinder failure and, in the worst case, leads to engine failure.

  Therefore, since the anti-wear ring does not reach the upper ring of the piston ring package sufficiently at the upper dead center position, there is always a somewhat wide area in the piston crown of the piston on the upper ring. Here, the anti-wear ring does not come into contact, and deposits formed there are not removed by the anti-wear ring.

  With reference to FIG. 1, these problems of the conventional piston will be described in more detail. It should be noted that in the present application, reference signs in the drawings relating to conventional features or examples are indicated with dashes, and features of embodiments according to the present invention are indicated with reference signs without dashes.

  FIG. 1 shows a conventional piston 1 'of a large two-stroke diesel engine used for a large container ship or the like. Although not shown in FIG. 1 for clarity, large two-stroke diesel engines typically have multiple cylinder liners. In this cylinder liner, the piston upper side 1011 'of the piston 1' defines the combustion space VB 'in the inserted state. In the cylinder liner, the piston 1 'is movably disposed back and forth in the axial direction along the piston axis A' of the cylinder liner between the top dead center and the bottom dead center. In this regard, as described above, the piston ring package 4 ′ has at least one piston ring configured as an upper ring 41 ′ closest to the piston upper side 1011 ′, and the piston ring package 4 ′ has the combustion space VB. It is formed on the jacket surface of the piston 1 ′ between the piston crown 101 ′ adjacent to the piston skirt 102 ′ away from the combustion space VB ′.

  During movement in the direction toward the top dead center, the piston 1 'eventually comes into contact with the anti-wear ring, i.e. the piston crown 101' is pressed against the anti-wear ring, resulting in the piston 1 'being a cylinder liner. The deposit D ′ is rubbed and polished on the outer jacket surface of the piston crown 101 ′ until the maximum point of the upper dead point, that is, the top dead center is reached. The anti-wear ring releases the majority of the outer jacket surface of the piston crown 101 'from the deposit D' at the top dead center, but the anti-wear ring itself is at the top dead center position of the piston 1 'at the piston ring package. The 4 'upper ring 41' is not fully reached. Since the anti-wear ring does not reach the upper ring 41 'enough at the top dead center, the deposit D' strip remains on the outer jacket surface of the piston crown 101 'on the upper ring 41' Not peeled off.

  As a result, a substantially annular strip of deposit D 'is formed on the jacket surface of piston 1' in the region of piston crown 101 'during further downward movement of piston 1' in the direction toward bottom dead center. Between the upper ring 41 'and the piston lower side 1011', which results in a well-known damage effect on the working surface of the cylinder liner. That is, the deposit D ′ remaining on the piston crown 101 ′ causes scratch-like damage on the surface of the working surface of the cylinder liner, or the remaining deposit D ′, for example, becomes less adherent with time. The ring groove adheres to the piston ring package 4 ′. This eventually damages the piston 1 ', in particular the piston ring groove or the piston ring. This damage at least shortens the service interval, shortens the service life of the cylinder liner members, and in the worst case leads to a malfunction of the cylinder liner and even the engine.

  Accordingly, it is an object of the present invention to provide a method for removing deposits from a piston, cylinder arrangement, and piston jacket surface. This avoids problems with deposits on conventional piston crowns.

  The subject-matter of the invention that fulfills these objectives is characterized by the features of the independent claims.

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

  Accordingly, the present invention relates to a reciprocating piston combustion engine having at least one cylinder liner, particularly a piston for a large two-stroke diesel engine. The piston is movably disposed back and forth between the top dead center and the bottom dead center of the cylinder liner in the axial direction along the piston axis. Wherein a piston ring package having at least one piston ring configured as a closest upper ring on the upper side of the piston is between the piston crown adjacent to the combustion space and the piston skirt remote from the combustion space. Formed on the jacket surface of the piston. In the present invention, a notch is provided on the jacket surface of the piston in the region of the piston crown between the upper ring and the upper side of the piston.

  A notch is provided in the piston crown above the upper ring so that deposits do not peel away and remain close to the upper ring as in the prior art, and the anti-wear ring is the rest of the piston crown. The entire jacket surface is released from the deposit. In the present invention, the notch is conventionally located in the region above the upper ring that is not reached by the anti-wear ring, and in which some annular region of deposit remains on the jacket surface. The notch according to the invention is formed in the circumferential direction around the piston crown and the anti-wear ring reaches at least this upper margin, preferably partially covering the notch when the piston is at top dead center .

  In the present invention, the entire outer jacket surface of the piston crown above the notch is significantly freed from deposit damage by the anti-wear ring. In addition, the notch temporarily stores deposits peeled off by the anti-wear ring, and the deposits do not contact the working surface of the cylinder liner, for example, deposits may enter the piston ring groove. It won't happen. Deposits temporarily stored in the notches are then moved gradually, for example by cylinder lubricant, or blown through a scavenging slit close to the bottom dead center, these are no longer It will not affect the cylinder liner malfunction.

  In a preferred embodiment of the invention, the predetermined radial ring section of the upper ring bounds the notch in the direction towards the piston skirt. That is, the notch is directly bounded by the upper ring without any space, the width of the radial ring section is up to 30% of the total radial ring width of the upper ring, and the radius of the upper ring It is preferably between 0.5% and 15% of the ring width in the direction, more preferably between 1% and 5%. As a result, a part of the gas pressure stored in the piston ring package can be easily retracted to the notch, and for example, the remainder of the deposit stored in the notch can be easily blown off. become.

  On the other hand, in another embodiment, a space area with a diameter corresponding to the diameter of the piston crown is provided between the upper ring and the notch. In the present invention, it is significant to place the upper ring some distance away from the notch. The space region preferably has a diameter smaller than the diameter of the piston crown in the upper region above the notch. The envisaged deposits in the space area thereby do not contact the cylinder working surface. The lower end portion of the anti-wear ring needs to protrude toward the notch when the piston is disposed at the position of the upper dead center.

  In this regard, the contour of the notch is particularly preferably formed asymmetrically with respect to the piston axis. The contour of the notch may have a smaller gradient in the direction toward the upper ring along the piston axis than in the direction toward the upper side of the piston. Thereby, for example, the peeled-off deposit in the notch portion cannot easily dissipate upward when the piston moves downward. Alternatively, they are “captured” in the stepper top region of the notch, where they are gradually mixed with lubricant and / or blown through a scavenging slit near the bottom dead center.

  Peeled deposits preferably remain in the notches until they are removed from the notches, or are removed directly in a predetermined direction and / or moved out of the notches, for example. The surface of the notch may have a suitable structure, for example. This structure may be formed, for example, by one or more grooves along the circumference of the piston axis, for example a spiral groove.

  Furthermore, the present invention relates to a piston liner arrangement for a reciprocating piston combustion engine having a piston arranged in a cylinder liner, in particular a large two-stroke diesel engine, wherein the piston upper side of the piston defines a combustion space, the piston being In the axial direction along the piston axis, the cylinder liner is disposed movably back and forth between the top dead center and the bottom dead center of the cylinder liner. Wherein a piston ring package having at least one piston ring configured as a closest upper ring on the upper side of the piston, between the piston crown adjacent to the combustion space and the piston skirt remote from the combustion space, Formed on the jacket surface of the piston. In the present invention, a notch is provided in the jacket surface of the piston in the region of the piston crown between the upper ring and the upper side of the piston.

  In practice, it is preferred that an anti-wear ring be formed in a conventional manner in the area of the top dead center of the cylinder liner. In the operating state, the anti-wear ring cooperates with the notch of the piston and transports deposits to the notch by the anti-wear ring on the jacket surface of the piston in the region of the piston crown. To do.

  In particular, the end of the anti-wear ring on the piston side may fully or completely cover the notch in the region of the top dead center of the piston.

  In this regard, for example, the crosshead may be provided with a well-known compression shim for setting the position of the top dead center. It is particularly preferred that the notch is configured such that it is at least partially covered by an anti-wear ring at the location of the top dead center that can be set by a compression shim.

  Furthermore, the present invention is a method for removing deposits from the piston jacket surface of a reciprocating piston combustion engine having at least one cylinder liner, particularly a large two-stroke diesel engine, wherein the piston upper side of the piston in the cylinder liner is The combustion space is defined in the inserted state, and the piston is moved back and forth between the top dead center and the bottom dead center of the cylinder liner in the axial direction along the piston axis. Wherein a piston ring package having at least one piston ring configured as a closest upper ring on the upper side of the piston, between the piston crown adjacent to the combustion space and the piston skirt remote from the combustion space, Formed on the jacket surface of the piston. In the present invention, a notch is provided on the jacket surface of the piston in the region of the piston crown between the upper ring and the upper side of the piston, and the anti-wear ring provided to the cylinder liner in the notch. The at least part of the deposit on the jacket surface is scraped off in cooperation with

  In this regard, it is preferable that the position of the top dead center is set by a well-known compression shim, and the notch is covered by the anti-wear ring in the area of the top dead center.

It is a conventional piston. 2 is an embodiment of a cylinder arrangement with a piston according to the invention. 4 is another embodiment of a piston according to the present invention.

  Hereinafter, the present invention will be described in more detail with reference to the drawings. The drawings are shown schematically.

  FIG. 1 shows the problem of a conventional piston. This problem is solved for the first time by the present invention. Since FIG. 1 has already been described in detail, it is possible to move directly to the description of FIG. FIG. 2 shows a practically particularly important embodiment of the cylinder arrangement according to the invention.

  In this case, a cylinder liner 3 with a cylinder liner arrangement of a reciprocating piston combustion engine 2, which is a large two-stroke diesel engine, is schematically shown with reference to FIG. The cylinder arrangement has the piston 1 arranged in the cylinder liner 3, and the piston upper side 1011 of the piston 1 defines the combustion space VB in the same manner as in the prior art. The piston 1 is disposed in the cylinder liner 3 so as to be movable back and forth between the top dead center OT and the bottom dead center in the axial direction along the piston axis A. The piston ring package 4 is formed on the jacket surface of the piston 1 between the piston crown 101 adjacent to the combustion space VB and the piston skirt 102 away from the combustion space VB. In addition to the piston ring, it has a piston ring configured as an upper ring 41 closest to the piston upper side 1011. In the present invention, in the region of the piston crown 101, a notch 5 is provided on the jacket surface of the piston 1 between the upper ring 41 and the piston upper side 1101.

  As in the prior art, an anti-wear ring APR is formed in the area of the top dead center OT of the cylinder liner 3. In the cylinder arrangement according to the invention, the anti-wear ring APR cooperates with the notch 5 of the piston 1 in the operating state, and the deposit D on the jacket surface of the piston 1 in the region of the piston crown 101 is the anti-wear ring APR. Is transferred to the notch 5. As shown in the figure, the end portion of the anti-wear ring APR covers the notch 5 in the region of the upper dead center OT of the piston 1 on the piston side.

  In this regard, the predetermined radial ring section 410 of the upper ring 41 bounds the notch 5 in the direction towards the piston skirt 102. That is, in the particular embodiment of FIG. 2, the upper ring 41 is directly adjacent to the notch 5. The width of the radial ring section 410 immediately adjacent to the notch is between about 0.5% and 15% of the radial ring width 411 of the upper ring 41.

  As will be readily understood, the contour K of the notch 5 is formed asymmetrically with respect to the piston axis A, here in particular in the direction towards the upper ring 41 along the piston axis A, the piston upper side 1011. Has a smaller slope than the direction towards

  Depending on the embodiments already described, the surface 51 of the notch 5 may have a suitable structure. In particular, this structure may be formed, for example, by one or more grooves along the periphery of the piston axis A.

  Another embodiment of the piston 1 according to the invention is schematically shown in FIG. FIG. 3 differs from the piston 1 according to FIG. 2 only in that a space region 6 is provided between the upper ring 41 and the notch 5. This diameter corresponds to the diameter of the piston crown 101. This means that in the example of FIG. 3, the upper ring 41 is not directly adjacent to the notch 5 but rather is separated by the space region 6. The space region 6 forms a kind of bridge between the notch 5 and the upper ring 41. Thereby, in particular, the deposit D accumulated in the notch 5 is significantly suppressed from moving to the ring groove of the upper ring 41.

  The space region 6 preferably has a diameter smaller than the diameter of the piston crown 101 in the upper region above the notch 5. Thereby, the assumed deposit in the space region 6 does not come into contact with the cylinder operating surface. When the piston 1 is disposed at the top dead center position, the lower end of the anti-wear ring APR needs to protrude into the notch 5.

  It will be apparent to those skilled in the art that the above illustrations according to the embodiments of the present invention are only examples, and that all suitable combinations of the embodiments are included in the present invention.

Claims (15)

A reciprocating piston combustion engine having at least one cylinder liner, in particular a piston for a large two-stroke diesel engine,
In the cylinder liner, the piston upper side of the piston defines a combustion space in the inserted state,
The piston is arranged to move back and forth between the top dead center and the bottom dead center of the cylinder liner in the axial direction along the piston axis,
A piston ring package having at least one piston ring configured as a closest upper ring on the upper side of the piston, the piston jacket between a piston crown adjacent to the combustion space and a piston skirt remote from the combustion space Formed on the surface,
A piston, characterized in that a notch is provided on the jacket surface of the piston in the region of the piston crown between the upper ring and the piston upper side.   2. The piston according to claim 1, wherein a predetermined radial ring section of the upper ring borders the notch in a direction toward the piston skirt.   The radial ring section width is at most 30% of the radial ring width of the upper ring, preferably between 0.5% and 15% of the radial ring width of the upper ring, more preferably Piston according to claim 1 or 2, characterized in that is between 1% and 5%. A space region is provided between the upper ring and the notch, and the diameter of the space region corresponds to the diameter of the piston crown;
4. The piston according to claim 1, wherein a diameter of the space region is smaller than a diameter of the piston crown in an upper region above the notch.   5. The piston according to claim 1, wherein the contour of the notch is formed asymmetrically with respect to the piston shaft.   6. The piston according to claim 5, wherein the contour of the notch has a smaller gradient along the piston axis in a direction toward the upper ring than in a direction toward the upper side of the piston.   7. The piston according to claim 1, wherein the surface of the notch has a structure.   8. The piston according to claim 7, wherein the structure is formed by a groove along the circumference of the piston shaft. A reciprocating piston combustion engine having a piston disposed in a cylinder liner, particularly a cylinder liner arrangement for a large two-stroke diesel engine,
The piston upper side of the piston defines a combustion space, and the piston is arranged movably back and forth between the top dead center and the bottom dead center of the cylinder liner in the axial direction along the piston axis.
A piston ring package having a piston ring package having at least one piston ring configured as a closest upper ring on the upper side of the piston, between a piston crown adjacent to the combustion space and a piston skirt remote from the combustion space. Formed on the surface,
Cylinder liner arrangement, characterized in that a notch is provided on the jacket surface of the piston in the region of the piston crown between the upper ring and the upper side of the piston. An anti-wear ring is formed in the upper dead center region of the cylinder liner;
In the operating state, the anti-wear ring cooperates with the notch of the piston, and in the region of the piston crown, on the jacket surface of the piston, the anti-wear ring causes the deposit to be brought into the notch. 10. The cylinder arrangement according to claim 9, wherein the cylinder arrangement is conveyed.   11. The cylinder arrangement according to claim 9, wherein an end of the anti-wear ring on the piston side covers the notch in the region of the upper dead center of the piston.   12. A cylinder arrangement according to any one of claims 9 to 11, characterized in that a compression shim is provided for setting the position of the upper dead center.   13. The cylinder arrangement according to claim 12, wherein the notch is configured such that the notch is covered with the anti-wear ring at a set position of the upper dead center. A method for removing deposits from a jacket surface of a piston of a reciprocating piston combustion engine, particularly a large two-stroke diesel engine having at least one cylinder liner, comprising:
The piston upper side of the piston in the cylinder liner defines a combustion space in the inserted state,
The piston is moved back and forth between the top dead center and the bottom dead center of the cylinder liner in an axial direction along the piston axis;
A piston ring package having a piston ring package having at least one piston ring configured as a closest upper ring on the upper side of the piston, between a piston crown adjacent to the combustion space and a piston skirt remote from the combustion space. Formed on the surface,
A notch is provided in the jacket surface of the piston in the region of the piston crown between the upper ring and the upper side of the piston, in which the notch cooperates with an anti-wear ring provided on the cylinder liner. By which at least a portion of the deposit is scraped off on the jacket surface. The position of the top dead center is set by a compression shim,
15. The method of claim 14, wherein the notch is covered by the anti-wear ring in the area of the top dead center.

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