WO2000040849A1 - Reciprocating piston engine - Google Patents

Abstract

The invention relates to a reciprocating piston engine with at least one cylinder whose cylinder liner (2) is provided with at least one groove-shaped oil pocket (8) in the area of the running surface (4) of said liner (2), whereby the running surface (4) is assigned to the piston (6). The oil pocket (8) is laterally defined by material areas which are provided with an enhanced resistance to wear capacity when compared with the base material of the cylinder liner (2) outside thereof. In order to obtain higher operational reliability, the material areas which respectively and laterally define one oil pocket (8) are configured as a filling (11) for a groove (10) whose depth (d) corresponds at least to the maximum wear and tear thickness of the cylinder liner (2).

Description

 Reciprocating machine

The invention relates to a reciprocating piston engine, in particular a large two-stroke diesel engine, with at least one cylinder, the cylinder liner of which, in the area of its tread facing the piston, has greater wear resistance than the material areas having the base material of the cylinder liner for lateral limitation of at least one groove-shaped oil pocket.

A reciprocating piston internal combustion engine of this type is known from JP 6-105102 B2. In this known arrangement, the cylinder liner is provided with a corrugated contour on the tread side to form groove-shaped oil pockets, the raised areas of this corrugated contour being hardened by a hardening process. To improve the running-in properties, the hardened areas can be provided with a MoS ₂ coating, but this quickly disappears. The production of a shaft contour and the implementation of a hardening process that is limited to the raised areas are comparatively complex. In addition, experience has shown that the hardening depth that can be achieved by the hardening process is comparatively small. In addition, the degrees of hardness that can only be achieved by a hardening process are also limited. In the known arrangement, therefore, only a comparatively short service life of the shaft contour is achieved. Another disadvantage is that the hardening, which is limited locally to the raised areas, can also lead to undesired warping and to undesirable structural changes in the adjacent material areas. The known arrangement therefore proves to be not simple and durable enough. Proceeding from this, it is therefore the object of the present invention to improve a reciprocating piston machine of the type mentioned at the outset using simple and inexpensive means in such a way that a long service life of the cylinder liner can be achieved.

This object is achieved according to the invention in that the material regions provided for the lateral delimitation of an oil pocket are designed as a groove, the depth of which corresponds at least to the maximum wear thickness of the cylinder liner.

These measures advantageously allow a free choice of material with regard to the groove fillings and thus the oil pocket limits. It is therefore possible to use a material that is different from the base material and that is better suited to the needs that arise than the hardened base material. The depth of the grooves can go far beyond the hardening depth that can be achieved in a hardening process. During production, a smooth surface initially results, which can be processed comparatively easily, for example honed. Due to the lower wear resistance of the base material, it wears faster in the area between the groove fillings made of foreign material, which automatically results in the desired oil pockets. These remain until the cylinder liner is completely worn out. The measures according to the invention therefore completely avoid the disadvantages of the known arrangement described at the outset.

Advantageous refinements and appropriate further training of the higher-level measures are specified in the subclaims. The filling can expediently consist of an at least partially ceramic material, preferably a ceramic-metal mixture (cermet). This results in a particularly high level of stability. In addition, materials of the type mentioned can be obtained in a very simple manner, for example in plasma

High-speed spraying or laser coating can be applied. Another advantageous measure can be that the depth of the grooves that laterally delimit an oil pocket is greater than the maximum wear thickness of the cylinder liner. This ensures that the slot fillings are well anchored in the base material until the cylinder liner is completely worn. This can also be beneficial if the groove cross section increases inwards.

Further advantageous refinements and expedient further developments of the superordinate measures are specified in the remaining subclaims and can be found in more detail in the following description of the examples with reference to the drawing.

In the drawing described below:

FIG. 1 shows a cylinder of a large two-stroke diesel engine, partly in section,

2 shows an enlarged section of the region of the arrangement according to FIG. 1 provided with oil pockets and FIG. 3 shows an enlarged section through a groove provided with a filling of the arrangement according to FIG. 1.

The present invention is used in reciprocating piston engines, in particular reciprocating piston internal combustion engines, preferably in the form of slow-running two-stroke large diesel engines. The structure and mode of operation of such arrangements are known per se and therefore require no further explanation in the present context.

The cylinder of a large two-stroke diesel engine shown in FIG. 1 contains a cylinder liner 2 provided with inlet slots 1, onto which a cylinder head 3 containing an outlet arrangement, not shown, is placed. The inside of the cylinder liner 2 is designed as a running surface 4, with which a piston 6, provided with circumferential piston rings 5, interacts and disengages. The tread 4 is supplied with lubricating oil via lubricating oil supply lines 7. To achieve a good distribution of the lubricating oil and in particular a good supply of lubricating oil to areas in which experience has shown that the supply of lubricating oil is inadequate, for example the upper area of the running surface 4, suitable oil pockets 8, which are only indicated in FIG. 1, are provided in this area. The depressions forming the oil pockets 8 are not present from the start. However, measures are provided from the start which cause the depressions on which the oil pockets 8 are based to develop automatically during operation due to wear on the base material on which the cylinder liner 2 is based.

The oil pockets 8 are laterally delimited by material areas 9 flanking them. An oil pocket 8 can form between each two such material areas 9. The material regions 9 which laterally delimit an oil pocket 8 are, as can be seen from FIGS. 2 and 3, designed as a filling 11 of a respectively assigned groove 10. The material forming the filling 11 has greater wear resistance than the base material of the cylinder liner 2, which generally consists of cast steel. In the new state, the grooves 10, as indicated in FIG. 3, are filled to the level of the tread 4, so that a smooth surface results which can be easily machined, for example honed. First, the grooves 10 are cut. The filling 11 is then introduced. Then the tread 4 is finished.

Due to the higher wear resistance of the material forming the filling 11 compared to the base material on which the cylinder liner 2 is based, the wear of the base material is greater during the running-in phase than the wear of the fillings 11, as indicated by broken lines in FIG. This therefore results in the respectively desired, groove-shaped oil pocket 8 between two mutually adjacent fillings 11.

To form the filling 11, a material can be expediently used which consists entirely or at least partially of ceramic material, for example a ceramic-metal mixture (cermet). This material can expediently contain carbides and / or oxides and / or nitrides and / or borides and / or silicates with Cu and / or Al bronze and / or Ni and / or NiCr and / or Mo and / or Al graphite and / or Ni graphite and / or Al-Br graphite and an organic binder, the carbides, oxides, nitrides, borides, silicates advantageously being present with 10-60% in the hard phase and 5-80% in the soft phase. It has proven to be particularly advantageous if the carbides, oxides, nitrides, borides and silicates are present as Cr compounds. CrO is a particularly useful material because it not only has high stability and a high working temperature, but is also non-corrosive and non-oxidizing.

In an advantageous embodiment of the above-mentioned specifications, the filling (11) can contain 20-50%, preferably 20-40% carbides and / or oxides and / or nitrides and / or borides and / or silicates as well as at least 20% Al bronze -40%, preferably 60-80%. Preferred configurations can be 20-40% oxides mixed with 60-80% Al bronze or 30-50% oxides, nitrides or carbides mixed with at least Al bronze, or preferably with 10-20% Mo and 20-30% Ni or NiC or contain 20-40% AI bronze. Materials of this type can be applied in an arc, flame, plasma or high-speed spraying process or can be introduced into the associated groove 10.

Another group of materials containing silicone and boron, each with a share of 0.1-10%, can also be applied in the above-mentioned manner. Preferred material compositions in this connection are 10-18% Cr, 2-3% Fe, 2-4% Si, 2-4% B, 0.1-0.5% C and Ni as the balance or 10-18% Cr, 2- 3% Fe, 2-4% Si, 2-4% B, 0.1-0.5% C, 6-12% Mo, 0.1-0.5% C, 30-40% Co and Ni as Balance or 10-18% Cr, 2-3% I, 2-4% Si, 2-4% B, 0.1 -0.5% C, 6-12% Mo, 1-6% Cu, 0, 1-0.5% C and Ni as balance or 10-18% Cr, 2-3% I, 2-4% Si, 2-4% B, 0.1-0.5% C, 6- 12% Mo, 10-20% Ni, 65-88% WC and 12% Co. Flame, induction or laser sintering can also be considered here.

When the filling 11 is formed as a sintered filling, a material can also be used which contains carbides and / or oxides and / or nitrides and / or borides and / or silicates with 10-60% in the hard phase and 5-80% in the soft phase Phase as well as 2-10% Cu, 20-30% Al-bronze, 10-85% Ni or NiCr, 10-30% Cr, 0.1-5% carbon, 1-8% Fe, 2-15% Mo or Mo sulfide or Mo disulfide or Mo oxide or Mo Contains dioxide or Mo peroxide, 2-7% Cu, 10-40% Co, 30-80% WC or 88% WC and 12% Co.

Powder materials are also suitable. For example, a powder with 0.2-5% C, 20-50% Cr, 1-20% Mo, 1 -20% V, 0.1-4% Si or B, 0.1-5% Mn, 0.1 -5% Fe, 0.5-50% carbides, oxides, nitrides, borides or silicates, Mo sulfides / dioxides / oxides / disulfides or Mo peroxides are used, silicone and / or boron each having 0, 1 -5% and the rest Ni can be provided. A particularly preferred material in this connection consists of 20-30% Cr, 1-10% Mo, 2-3% C, 2-5% V, 0.2-1% Mn, 0.2-4% Si or B and Ni as the rest.

Alternatively, the filling 11 can also be designed as a welding job. A material can be used that 2-20% Al, 0.5-10% Fe, 0.1-8% Mn, 0.1 -2% Si, 0.1 -10% o Ni, 0.1 Contains -2% C and at least one of the components Sb, Co, Be, Cr, Sn, Cd, Zn, Pb with at most 5-20% and the rest Cu. A particularly preferred composition can contain 14-17% Al, 3-5% Fe, 1-3% Mn, 0.1-2% Si, a maximum of 0.3% C and the rest Cu.

The depth of the groove 10 indicated in FIG. 3 at d corresponds at least to the maximum wear thickness of the cylinder liner 4. The depth d is expediently greater than the maximum wear thickness, so that even with a completely worn cylinder liner 2, the filling 11 is still well anchored in the base material is. In this context it can also be advantageous if the cross section of the groove 10 is widened inwards, as indicated in FIG. 2 by the cross-sectional shape 12 drawn with broken lines. A preferred groove depth can be in the range between 0.1 to 0.4% of the diameter D of the tread 4. The clear width of the oil pockets 8 formed corresponds to the distance between the associated grooves 10, each provided with a filling 11. This distance, indicated at w in FIG. 2, is preferably in the range between 1 to 2% of the diameter D of the tread 4. The clear width Width of the grooves 10 and thus the width b of the fillings 11 assigned to them suitably corresponds to the groove depth d. This ensures good stability against shear stress. One or more oil pockets 8 can be provided. The grooves 10 assigned to them, each provided with a filling 11, are expediently arranged where, according to previous experience, the risk of insufficient lubrication and, accordingly, the risk of heat corrosion etc. is particularly great. This is especially the case in the upper area of the tread. In FIG. 1, the means provided to form an oil pocket 8 are arranged in the region of the running surface delimited by the first and second piston rings 5 in the top dead center position of the piston 6. A further oil pocket 8 or the means necessary for this can be provided in the area below the lowest piston ring 5. In the example shown, further oil pockets 8, which are arranged even deeper, are also provided.

The oil pockets 8 and, accordingly, the material areas delimiting them can be formed all around. In addition or as an alternative to this, one or more screw-shaped oil pockets 8 and, accordingly, the screw-shaped material regions 9 that delimit them can also be provided. These can extend over an area or over the entire guide length of the tread 4.

In the case of a screw-shaped oil pocket 8, the slope indicated at p in FIG. 1 can amount to approximately 1.5% to 20% of the diameter D of the tread 4. This slope can be constant over the entire length. However, a variable slope would also be conceivable in order to obtain a greater oil pocket density in particularly endangered areas than in less endangered areas.

In the example shown, the groove 10 and, accordingly, the filling 11 assigned to it have a rectangular or trapezoidal cross section. The inner edges can be rounded to avoid notch stresses.

Claims

Expectations 1. reciprocating machine, in particular two-stroke large diesel engine, with at least one cylinder, the cylinder liner (2) in the area of the piston (6) facing the tread (4) greater wear resistance than the base material of the cylinder liner (2) material areas (9) for lateral Contains at least one groove-shaped oil pocket (8), characterized in that the material areas (9) provided for the lateral limitation of each oil pocket (8) are designed as a filling (11) of a groove (10), the depth (d) of which is at least the maximum Wear thickness of the cylinder liner (2) corresponds. 2. Reciprocating machine according to claim 1, characterized in that the Filling (11) consists of an aluminum bronze, the 2-20% Al, 0.5-10% Fe, 0.1-8% Mn, 0.1-2% Si, 0.1-10% Ni, 0, 1-2% C and at least one of the components Sb, Co, Be, Cr, Sn, Cd, Zn, Pb, each with at most 5-20% and the rest Cu, preferably 14-17% Al, 3-5% Fe, 1 Contains -3% Mn, 0.1 -2% Si, maximum 0.3% C and balance Cu. 3. reciprocating piston machine according to claim 2, characterized in that the Filling (11) is at least partially designed as a welding job. 4. reciprocating piston machine according to claim 1, characterized in that the filling (11) consists at least partially of ceramic material. 5. Reciprocating machine according to claim 4, characterized in that the filling (11) consists of a ceramic-metal mixture (cermet). 6. Reciprocating piston machine according to claim 4 or 5, characterized in that the filling (11) carbides and / or oxides and / or nitrides and / or borides and / or silicates with Cu and / or Al bronze and / or Ni and / or NiCr and / or Mo and / or Al graphite and / or Ni graphite and / or Al-Br graphite and an organic binder. 7. reciprocating piston machine according to claim 6, characterized in that the Carbides, oxides, nitrides, borides, silicates with 10-60% in the hard phase and 5-80% in the soft phase. 8. Reciprocating piston machine according to claim 6 or 7, characterized in that the carbides, oxides, nitrides, borides, silicates are present as Cr compounds. 9. Reciprocating piston machine according to one of the preceding claims 4 to 7, characterized in that the filling (11) 20-50%, preferably 20-40%, carbides and / or oxides and / or nitrides and / or borides and / or silicates and at least still contains Al bronze with at least 20-40%, preferably 60-80%. 10. Reciprocating piston machine according to one of the preceding claims, characterized in that the filling (11) is at least partially designed as a spray application. 11. Reciprocating piston machine according to one of the preceding claims, characterized in that the filling (11) is at least partially designed as a sintered material. 12. Reciprocating piston machine according to one of the preceding claims, characterized in that the depth d of the grooves (10) is greater than the maximum wear thickness of the cylinder liner (2). 13. Reciprocating piston machine according to one of the preceding claims, characterized in that the cross section of the grooves (10) increases inwards. 14. Hubkoibenmaschine according to any one of the preceding claims, characterized in that the depth (d) of the grooves (10) is in the range between 0.1% to 0.4% of the diameter (D) of the tread 4. 15. Reciprocating piston machine according to one of the preceding claims, characterized in that the distance between two grooves (10) associated with the fillings (11) which each delimit an oil pocket (8) in the range between 1% to 2% of the diameter (D) of the tread ( 4) lies. 16. Reciprocating piston machine according to one of the preceding claims, characterized in that the width (b) of the grooves (10) corresponds approximately to the groove depth (d). 17. Reciprocating piston machine according to one of the preceding claims, characterized in that at least one helical oil pocket (8) is provided, each with a filling (11) provided with grooves (10), the pitch preferably being 1.5% to 20% of the diameter D of the tread (4). 18. Reciprocating piston machine according to one of the preceding claims, characterized in that at least in the upper region of the cylinder liner (1) the at least one oil pocket (8) associated, each with a filling (11) provided with grooves (10) are provided. 19. Reciprocating piston machine according to one of the preceding claims, characterized in that at least one oil pocket (8) is provided which is continuous over the guide length of the tread (4) and is provided with grooves (10) each provided with a filling (11).