CN1333859A - Reciprocating piston engine - Google Patents

Abstract

The invention relates to a reciprocating piston engine comprising at least one cylinder whose cylinder liner (2) is provided with at least one groove (9) which forms an oil pocket (8) and which is situated in the area of the running surface (4) of said liner, whereby the running surface (4) faces the piston (6) assigned to the cylinder. The aim of the invention is to create a particularly protective operating mode and thus attain a particularly long service life of the cylinder liner (2). To this end, the groove (9) has a depth which corresponds to the maximum depth of the wear of the cylinder liner (2). A filling (10) is allocated to said groove. The material used for the filling (10) in the groove (9) has a lower capacity of resistance to wear than the basic material of the cylinder liner (2).

Description

piston mechanical

The invention relates to a piston machine, in particular a large two-stroke diesel engine, having at least one cylinder, the cylinder liner of which is provided in the region of its sliding surface facing the associated piston with at least one groove for forming an oil chamber .

Such a piston internal combustion engine is known from GB 1473058. The cross-section of the oil chamber or multiple oil chambers in this known device corresponds to the cross-section of the respective associated groove cut into the cylinder liner. The depth of the grooves decreases with increasing cylinder liner wear. In this known device, too, the depth of the oil chamber formed by the groove itself is reduced to the same extent. Therefore along with the prolongation of service time its working condition is deteriorating constantly. Yet another very particular disadvantage of the known device is that particles of material exfoliated from the cylinder liner due to possible thermal corrosion etc. cannot settle in the grooves of the known device. There is therefore the risk that the material particles fall between the cylinder liner and the piston and are crushed or ground up there, which can lead to damage and intense local heating and thus accelerate thermal corrosion and/or seizure. The operation of this known device thus proved to be less than reliable.

Proceeding from this, it is therefore the object of the invention to improve a device of the same type in a simple and cost-effective manner so that it achieves a high degree of operational reliability over the long term while avoiding the disadvantages mentioned.

This object is achieved according to the invention in that a filler is provided in the groove, the depth of the groove is at least equal to the maximum wear thickness of the cylinder liner, and the material of the filler forming the groove has a smaller hardness than the base material of the cylinder liner. abrasion resistance.

In the new case, the groove can be completely filled with the configured filler. This results in a smooth, non-profiled outer surface, which is easy to machine. However, during the running-in period, due to the wear of the filler material faster than that of the base material, the required oil chamber is already formed, the depth of which is undoubtedly smaller than the depth of the groove and the progressive wear of the cylinder liner develops to a degree dependent on this wear. Therefore, although the groove depth gradually decreases, over a long period of time, a relatively uniform state is formed with respect to the cross section of the oil chamber, which ensures reliable lubrication of the relevant area of the cylinder liner over a long period of time and Thermal corrosion and seizure are thus reliably avoided. The depth of the formed oil chamber or multiple oil chambers is related to the intensity of wear. The greater the wear, the deeper the individual oil chambers and thus the stronger the lubrication, and vice versa. So in fact form an automatic adjustment type. It is thus also possible to reduce specific fuel consumption. But another very special advantage of the measure according to the invention is that the material particles exfoliated by the inevitable wear of the cylinder liner can be pressed into the softer filling material and fixed in place. Free movement of particles of this material is thus prevented by the grooves provided with filler. The groove provided according to the invention therefore also acts as a highly effective stop groove. The measures according to the invention can therefore also be used to effectively prevent damage and malfunctions caused by exfoliated material particles of the cylinder liner, such as material welding or material bonding, which lead to accelerated thermal corrosion and seizure. A long service life is thus advantageously ensured by means of the measures according to the invention.

Advantageous refinements and expedient developments of the measures described above are specified in the subclaims. In this way, the material of the filler material forming the groove may suitably have a stronger thermal expansion than the base material of the cylinder liner. This allows the filler material to expand faster than the matrix material in the event of overheating, so that the piston can be stabilized and so-called seizure can thus be prevented. This advantage is all the more pronounced when the filling material advantageously also has dry lubricating properties.

In an advantageous further development of the above-mentioned measures, the filling of the grooves can at least partially consist of aluminum and/or aluminum bronze and/or graphite, wherein preferably 9-11% Al, 0.5-2% Fe and the rest are Cu aluminum bronze. This material has the superior properties required above. However, it is also possible to use, for example, graphite alloys which preferably contain 15-25% graphite and 75-85% aluminum bronze. This material also has a very high level of performance that is required.

At least one helical groove can advantageously be provided. This results in a particularly good distribution and a particularly good delivery of the oil along a large area of the cylinder liner and thus a particularly high degree of reliability.

According to a further advantageous development of the aforementioned measures, the filler material can be formed as a welded or sprayed layer, depending on the suitability of the materials used. This ensures a reliable adhesion of the void-free filler to the matrix material in a simple manner.

Further advantageous developments and expedient refinements of the measures described above are to be found in the remaining subclaims and can be seen in more detail from the following description of examples with reference to the drawings.

In the drawings described below:

Fig. 1 shows a partial section of a cylinder of a large two-stroke diesel engine;

2 shows an enlarged view of the region of the sliding surface of the cylinder liner provided with grooves according to the invention;

Figure 3 shows a scheme with respect to the groove cross-section, and

FIG. 4 shows another variant with regard to the groove cross-section.

The invention finds application in piston machines, in particular piston internal combustion engines, of large two-stroke diesel engines, preferably running slowly. The structure and mode of operation of such devices are known per se and therefore need not be explained in more detail here.

The cylinder of a large two-stroke diesel engine shown in FIG. 1 comprises a cylinder liner 2 provided with a plurality of intake ports 1, on which is mounted a cylinder head 3 including an exhaust device not shown in detail therein. The inner surface of the cylinder liner 2 is formed as a sliding surface 4 which cooperates with a reciprocating piston 6 which is provided with piston rings 5 around its circumference. The sliding surface 4 is supplied with lubricating oil via a lubricating oil supply line 7 .

In order to achieve a good lubricant distribution and in particular a good lubricant supply in areas where the empirically insufficient lubricant supply, such as the upper region of the sliding surface 4, is provided with suitable oils, which are only indicated in FIG. Room 8.

For this purpose, as can be best seen from FIG. 2 , at least one cut-in groove 9 is provided in the region of the sliding surface 4 , in which an associated oil chamber 8 is formed. The groove 9 contains a filler material 10 which consists of a material which is less wear-resistant than the base material of the cylinder liner. Cylinder liners are usually constructed of cast steel. Aluminum bronze may advantageously be used to form filler 10 . As demonstrated by experiments, the aluminum bronze should contain at least 2-20%, preferably 9-11% Al, 0.5-8%, preferably 0.5-2% Fe and the remainder Cu. Specific ingredients address the conditions present in each case. The higher the Fe content, the higher the hardness of the material. Good results have been obtained in cylinder liners of large two-stroke diesel engines with aluminum bronzes consisting of:

2-20%, preferably 9-11% Al,

0.5-8%, preferably 0.5-2% Fe,

0.1-8% Mn, 0.1-2% Si, 0.1-1% Ni,

0.1-2% C, at least one of Sb, Co, Be, Cr, Sn, Cd, Zn and Pb with a maximum content of 5-20%, and the rest is Cu.

However, it is also possible to use graphite alloys such as nickel graphite or silicon graphite or aluminum graphite or aluminum bronze graphite, which respectively contain 5 to 60%, preferably 15 to 25%, of graphite and respectively 40 to 95%, preferably 75 to 85%, of other components. %content. Particularly good corrosion and seizure resistance can be obtained with aluminum bronze graphite alloys. The composition of the aluminum bronze can be in accordance with the above-mentioned composition.

The filler material 10 can advantageously be introduced into the previously produced trench 9 by means of a spray layer applied by laser spraying or arc spraying, eg plasma spraying. Of course, the filling material 10 of the groove 9 can also be made into a welding layer. Aluminum bronzes containing 9-11% Al, 1-3% Fe, 4-6% Ni, 1-2% Mn and the remainder Cu are particularly suitable for this purpose.

For this purpose, the filling of the groove 9 is expediently up to the level of the sliding surface 4 . The sliding surface 4 can then be fully machined, for example honed. Since the material forming the filler 10 is less wear-resistant than the base material of the cylinder liner 2 , the wear of the filler 10 is already greater than the wear of the cylinder liner 2 during the running-in phase. The ground material is washed away by the lubricating oil. The required oil chamber 8 is thus formed, which is maintained throughout the life of the cylinder liner.

The depth of the groove 9 indicated by d in FIG. 2 therefore corresponds at least to the wear thickness of the cylinder liner 2 and is preferably slightly greater. However, because such a deep groove 9 is provided with a filler material 10, it also wears as the cylinder liner wears, but it wears a little faster and forms a rather uniform, differential pattern throughout the life of the cylinder liner 2. The cross-sectional shape of the oil chamber 8 in the cross-section of the groove 9 itself.

A material can advantageously be used for forming the filler material 10 , which has a greater expansion property when heated than the base material of the cylinder liner. The materials suggested above have such properties. In the event of local overheating, the filler material 10 thus expands more strongly than the base material of the cylinder liner 2 , so that the piston 6 can be stabilized, as shown in FIG. 2 by the expansion line 11 indicated by the dashed line. The material of the filler 10 suggested above also has good dry lubrication properties, which results in an advantageous support especially in the event of overheating. However, it is also possible to combine or insert additional materials with good dry lubricating properties in the filler material.

One or more grooves 9 may be provided. Based on previous experience, they are expediently arranged at locations where there is a risk of insufficient lubrication and thus hot corrosion etc. This is the case in particular in the upper region of the sliding surface 4 . In FIG. 1 , an annular groove with a corresponding oil chamber 8 is provided in the region of the sliding surface 4 bounded by the first and second piston ring 5 in the upper dead center position of the piston 6 . A further groove, which is assigned the oil chamber 8 , is arranged in the region below the lowermost piston ring 5 . In the example shown, other deeper configurations of the oil chamber 8 are also shown.

The groove 9 serving as the basis for the oil chamber 8 can be formed as an annular radial groove. In addition or as an alternative, however, one or more helically extending grooves 9 with oil chambers 8 can also be provided. They can extend along a region of the sliding surface 4 or along its entire length.

FIG. 2 is based on a helically extending groove 9 . The pitch of the groove 9 denoted by P may be 1.5% to 20% of the diameter D of the sliding surface 4 . The lead P may be constant along the entire length of the trench. However, it is also possible to vary the lead in order to obtain a greater oil chamber density in particularly vulnerable areas than in less vulnerable areas. The depth d of the groove 9 is suitably within a range of 0.1% to 0.4% of the diameter D. As shown in FIG. The outlet width W is suitably 1% to 2% of the diameter D

In the example shown, the groove 9 has a cross-section that narrows from the outlet width W inwardly. This is to take into account that the rate of wear increases with increasing usage time. The groove 9 in FIG. 2 has an approximately U-shaped cross-section with sides inclined relative to the groove bottom. The inclination angle of the side surface indicated by α may be in the range of 30° to 60°. The transition between the groove bottom and the groove sides is suitably rounded, as indicated by the radius arrows.

The above-mentioned dimensional data also apply to the other variants according to FIGS. 3 and 4 . FIG. 3 shows a V-shaped groove 9 with an associated packing 10 including an oil chamber 8 . The groove 9 in FIG. 4 has a circular arc cross section. Here too, an inwardly tapering cross section and thus an inwardly tapering width of the packing 10 and the oil chamber 8 formed therein are formed.

Claims (18)

1. reciprocating machine, particularly large two-stroke diesel engine, it has at least one cylinder.Its cylinder liner (2) is provided with at least one groove that is used to form grease chamber (8) (9) at it in the zone of the slip surface (4) of the piston (6) of configuration, it is characterized in that, groove (9) has disposed a filler (10), the degree of depth of groove is equivalent to the greatest wear thickness of cylinder liner (2) at least, and the material that forms the filler (10) of groove (9) has less wear resistance than the body material of cylinder liner (2).

2. according to the described reciprocating machine of claim 1, it is characterized in that the material of the filler (10) of formation groove (9) has stronger thermal expansion than the body material of cylinder liner (2).

3. according to one of an aforesaid right requirement described reciprocating machine, the material that it is characterized in that forming the filler (10) of groove (9) has dry lubricating performance.

4. one of require a described reciprocating machine according to aforesaid right, the material that it is characterized in that forming the filler (10) of groove (9) is made of aluminium and/or aluminum bronze and/or graphite at least in part.

5. according to the described reciprocating machine of claim 4, it is characterized in that comprising aluminium, iron and copper at least for the aluminum bronze that the filler (10) that forms groove (9) is adopted.

6. according to one of an aforesaid right requirement described reciprocating machine, it is characterized in that the aluminum bronze that is adopted for the filler (10) that forms groove (9) comprises following alloy part at least:

2～20%, preferred 9～11%Al,

0.5～8%, preferred 0.5～2%Fe,

All the other are Cu.

7. according to claim 5 or 6 described reciprocating machines, it is characterized in that the aluminum bronze that is adopted for the filler (10) that forms groove (9) comprises following alloy part:

2～20%, preferred 9～11%Al,

0.5～8%, preferred 0.5～2%Fe,

0.1～8%Mn, 0.1～2%Si, 0.1～1%Ni, 0.1～2%C has at least a composition among Sb, Co, Be, Cr, Sn, Cd, Zn and the Pb of the highest 5～20% content respectively, and all the other are Cu.

8. according to one of claim 4～7 described reciprocating machine, it is characterized in that, the material that forms the filler (10) of groove (9) comprises 5～60%, preferred 15～25% graphite and 40～95%, preferred 75～85% aluminium and/or aluminum bronze and/or nickel and/or silicon.

9. according to one of an aforesaid right requirement described reciprocating machine, it is characterized in that being provided with at least one spiral groove (9).

10. according to one of an aforesaid right requirement described reciprocating machine, it is characterized in that, at least one groove (9) is set in the upper area of cylinder liner (2) at least.

11. according to one of an aforesaid right requirement described reciprocating machine, it is characterized in that, in the zone of the slip surface (4) that limits in the top dead center position of piston (6) by first and second piston rings (5) at least one groove (9) be set at least.

12. according to one of an aforesaid right requirement described reciprocating machine, it is characterized in that, in the zone of the top dead center position of piston (6) at least one groove (9) be set in the below of nethermost piston ring (5) at least.

13., it is characterized in that at least one groove (9) extends continuously along the guiding length of slip surface (4) according to one of an aforesaid right requirement described reciprocating machine.

14. according to aforesaid right one of require a described reciprocating machine, the helical pitch that it is characterized in that spiral groove (9) be slip surface (4) diameter 1.5%～20%.

15. according to aforesaid right one of require a described reciprocating machine, the degree of depth that it is characterized in that groove (9) be slip surface (4) diameter 0.1%～0.4%.

16. according to aforesaid right one of require a described reciprocating machine, the exit width that it is characterized in that groove (9) be slip surface (4) diameter 1%～2%.

17., it is characterized in that groove (9) inwardly has narrowed cross-section gradually according to one of an aforesaid right requirement described reciprocating machine.

18., it is characterized in that the filler (10) of groove (9) constitutes weld layer or sprayfused coating according to one of an aforesaid right requirement described reciprocating machine.

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