EP1350929B2 - Lubrication system for the cylinder of an internal combustion engine and method of lubricating the same - Google Patents

Description

The invention relates to a method for lubricating a reciprocating internal combustion engine, in particular a two-stroke large diesel engine with longitudinal rinse, according to the preamble of the independent claim.

Long-stroke two-stroke large diesel engines are often used as propulsion units for ships or even in stationary operation, e.g. for driving large generators for generating electrical energy used. The engines usually run for long periods in continuous operation, which places high demands on the reliability and availability. Therefore, for the operators in particular long maintenance intervals, low wear and an economical handling of fuels and supplies are central criteria in the selection of 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 the lubricating oil consumption also directly for the operating costs. Thus, the complex problem of lubrication of two-stroke large diesel engines is becoming increasingly important.

In two-stroke large bore diesel engines, piston lubrication is provided by lubrication means in the cylinder wall, which applies lubricating oil to the cylinder surface tread to minimize friction between the piston and the tread and thereby wear out the tread. So today with modern engines, such as the Sulzer RTA engines, the tread wear at less than 0.05 mm with a service life of 1000 hours. The lubricating oil flow is in such engines at about 1.3 g / kWh and less and should not least be further reduced for cost reasons as possible.

As lubrication systems for lubricating the treads quite different solutions are known, both in terms of the actual execution of the lubrication devices themselves, as well as the procedures for lubrication. Thus, lubricating devices are known in which the lubricating oil is applied through a plurality of lubricating oil openings, which are accommodated in the circumferential direction in the cylinder wall, in the radial direction on the piston passing to the lubricating oil piston, wherein the lubricating oil distributed by the piston rings in both the circumferential direction and in the axial direction becomes. Due to the fact that the lubricating oil is not applied over a large area to the running surface of the cylinder wall in this method, but more or less selectively between the piston rings on the side surfaces of the piston, the distribution of the lubricating oil on the tread is often insufficiently ensured, resulting in excessive heat development excessive friction and in the last consequence locally to a welding of the contact surfaces of piston and tread with subsequent material outbreak, so can lead to a piston seizure.

In order to ensure a better distribution of the lubricating oil, ie to ensure a more uniform lubricating oil film on the tread, is in the WO 00/28194 proposed a lubricating system in which the lubricating oil is sprayed under high pressure by means of atomizing nozzles, which are housed in the cylinder walls, substantially tangential to the cylinder wall in the scavenging air located in the combustion chamber, wherein the lubricating oil is atomized into small particles. As a result, the atomized lubricating oil is finely distributed in the scavenging air and thrown against the running surface of the cylinder wall by the centrifugal force of the swirl, which carry the scavenging air and thus also finely dispersed therein lubricating oil particles. In this method, although a significantly smoother Schmierölfim generated on the tread as in radial lubricating oil injection; A serious disadvantage of this method, however, is that a significant part of the lubricating oil used carried away with the scavenging air or is burned in the following combustion cycle with. This results in an unnecessarily high consumption of lubricating oil, which has a significantly negative effect on the operating costs. In addition, there are special requirements for the quality of the lubricating oil used, since not all lubricating oils can be atomized suitable finely, whereby the selection of lubricating oils available for lubrication is limited. In particular, cheaper lubricating oils, that is, lubricating oils of inferior quality, can be less readily atomized than high quality lubricating oils, which further reduces the effectiveness of the process when such lubricating oils are used.

The object of the invention is therefore to propose an improved method for lubricating a running surface of a cylinder wall of a cylinder of a reciprocating internal combustion engine, in particular a two-stroke large diesel engine with longitudinal rinse, by which method a better distribution of a lubricant on the tread of the cylinder wall is ensured and at the same time the amount To lubricant can be significantly reduced compared to known methods and thus a more economical operation of such reciprocating internal combustion engines is made possible.

The method solving these objects is characterized by the features of the independent claim.

Thus, according to the invention, a method is described below with reference to a lubrication system not belonging to the invention for lubricating a running surface of a cylinder wall of a cylinder of a reciprocating internal combustion engine, in particular a two-stroke large diesel engine with longitudinal scavenging, in which cylinder a piston is arranged back and forth along the tread proposed. The cylinder has at least one lubricant nozzle arranged in a recess of the cylinder wall for applying lubricant to the running surface. In this case, the lubricant nozzle is arranged and configured such that the lubricant in a plurality of lubricant jets can be applied to the running surface of the cylinder and a sputtering of the lubricant jet through the lubricant nozzle is largely avoidable.

The arrangement and design of the lubricant nozzles of the lubrication system ensures that the lubricant can be applied directly to the running surface of the cylinder wall of the cylinder of the reciprocating internal combustion engine. It has been shown that at the same time a uniform lubricant application and economical use is guaranteed.

In a preferred embodiment, the lubrication system comprises a plurality of lubricant nozzles, which are arranged along a circumferential line of the cylinder of Hubkolbenbrennkraftmaschien, for symmetry reasons, preferably at equidistant intervals. The area enclosed by the circumferential line is preferably perpendicular to a cylinder axis extending along the cylinder. Of course, it may also be possible in certain cases that the lubricant nozzles are not arranged on such a circumferential line, but in a different manner in the cylinder wall, for example on a spiral path extending in the direction of the cylinder axis. In addition, it is conceivable that the lubrication system comprises a plurality of lubricant nozzles, which are arranged along a plurality of parallel circumferential lines. For example, lubricant nozzles may be arranged on one or more such circumferential lines at different heights in the cylinder, for example in the vicinity of the lower reversal point of the piston movement in the cylinder and / or in the vicinity of the upper reversal point and / or between the upper and lower reversal point. This ensures that the tread is optimally supplied with lubricating oil everywhere.

The lubricant is applied directly to the tread in a substantially compact jet of lubricant. That is, a sputtering of the jet into fine particles is largely avoidable. For uniform contact with the running surface, the lubricant nozzles are arranged in the cylinder wall in such a way that the lubricant exits substantially tangentially with respect to the cylinder wall in a lubricant jet. The indication of direction tangentially always refers in the context of this application to the area of the cylinder wall in which the lubricant nozzle in question is accommodated.

The lubricant jet may in a preferred embodiment with respect to a cylinder axis, the direction in this application as usual parallel to the direction of movement of the piston of the reciprocating internal combustion engine, ie perpendicular to the radial direction of the cylinder to assume, exit at a predetermined angle in the tangential direction of the lubricant nozzle , By such a spiral application of the lubricant, it is possible to optimally apply a uniform lubricant film to the running surface both in the circumferential direction and in the axial direction. In this case, the lubricant nozzles may well be aligned in different directions with respect to the cylinder axis, whereby a larger area of the running surface with lubricant can be acted upon directly by the lubricant nozzles. Thus, e.g. As viewed in the circumferential direction, the lubricant nozzles may each be aligned alternately in different directions with respect to the cylinder axis at the same or different angular amounts. Also, a single lubricant nozzle may have a plurality of lubricant delivery orifices which equalize or different exit orifices, e.g. in that the outlet openings have the same or different opening cross-sections and are designed and arranged so that the lubricant can emerge in the same or in different directions. Of course, the lubricant nozzles can also be arranged such that the lubricant jet can emerge perpendicular to the cylinder axis from the lubricant nozzle. In addition, of course, any suitable combination of the aforementioned embodiments is conceivable.

In a further embodiment, the cylinder wall can additionally have a circumferential groove, for example in the form of a closed circular line, for storing the lubricating oil applied to the running surface. The surface that encloses the groove can be perpendicular or oblique on the cylinder axis. The groove can also form a non-closed curve in the form of a spiral in the cylinder wall. It is also conceivable that the groove has one or more separate sections which do not extend in the form of a closed curve over certain areas of the cylinder wall. Of course, any suitable combination of the various possible shapes of grooves is possible. In operation, excess lubricant can be scraped off into the grooves, for example, by the piston rings, so that the lubricant is available again for the lubrication of the piston at a later time.

Preferably, each lubricant nozzle is connected via a separate supply line with a metering unit, which the lubricant nozzle the necessary amount Lubricating oil at a predetermined time provides. It is also conceivable, however, that either a part of the lubricant nozzles or even all the lubricant nozzles are supplied with lubricant by means of a common feed line, for example in the form of a common rail system, from the metering unit. The dosing unit is preferably controlled or regulated by a freely programmable drive unit. This makes it possible, the amount and / or time of the supplied lubricant depending on various operating parameters, such as the speed, the load, the cylinder temperature or other operating parameters, or even, for example, depending on the fuel quality, the lubricant quality or the quality of others Operating materials to be determined during operation. Thus, it may be possible, for example, that lubricant does not have to be applied to the running surface of each lubricant nozzle at each working cycle, or the amount of lubricant to be applied can be adjusted individually, depending on the operating state and / or location in the cylinder. Of course, both the time of lubricant supply, as well as the amount of lubricant supplied, for example, additionally be carried out in dependence on the piston position.

In the inventive method for lubricating a running surface of a cylinder wall of a cylinder of a reciprocating internal combustion engine, in particular a two-stroke large diesel engine with longitudinal flush, in which cylinder a piston along the tread is arranged back and forth, is lubricated by at least one arranged in a recess of the cylinder wall lubricant nozzle applied to the tread. In this case, the lubricant is applied in a compact lubricant jet on the running surface of the cylinder wall and atomization of the lubricant jet through the lubricant nozzle is largely avoided.

Each lubricant nozzle is the lubricant from a metering unit, preferably fed to each lubricant nozzle via a separate supply line, wherein the metering unit can be controlled or regulated by means of a freely programmable drive unit so that the amount and / or the time of each lubricant nozzle supplied lubricant in Depending on different operating parameters can be specified.

Fig. 1

ein Ausführungsbeispiel eines Schmiersystems in einem Zylinder eines Grossdieselmotors;

Fig. 2

ein Zylinder mit Schmiersystem, Schmiermitteldüse, Dosiereinheit und Ansteuereinrichtung im Schnitt, gemäss Fig. 1 entlang der Schnittlinie A - A;

Fig. 3

Schmiersystem gemäss Fig. 2 mit Schmiermitteldüse und Schmiermittelstrahl

In the following the invention will be explained in more detail with reference to the drawing. In a schematic not to scale representation:

Fig. 1

an embodiment of a lubrication system in a cylinder of a large diesel engine;

Fig. 2

a cylinder with lubrication system, lubricant nozzle, dosing unit and control unit in section, according to Fig. 1 along the section line A - A;

Fig. 3

Lubricating system according to Fig. 2 with lubricant nozzle and lubricant jet

The lubrication system for a reciprocating internal combustion engine, which is hereinafter referred to in its entirety by the reference numeral 1, is particularly suitable for two-stroke large diesel engines with longitudinal scavenging, as they are widely used for example in shipbuilding. Fig. 1 shows, partially in longitudinal section, a portion of a cylinder 4 of a two-stroke large diesel engine with longitudinal rinse with the essential parts for understanding the invention, and an embodiment of the lubrication system 1. The presentation of other, known per se components of such cylinder 4, for reasons the clarity omitted.

Fig. 1 shows a portion of a cylinder 4 of a two-stroke large diesel engine in the area in which the lubrication system 1 is housed. The cylinder 4 essentially comprises a cylinder wall 3 which is delimited in the interior of the cylinder 4 by a running surface 2 and a piston 5 which is arranged in the direction of a cylinder axis 10 along the running surface 2 in the interior of the cylinder 4 back and forth. The piston has in known manner a piston rod 51, which is for driving the piston 5 with a crankshaft, not shown, and a combustion chamber 15 facing Kolbenoberlfäche 52. In the tread 2 facing side surface 53 of the piston 5 are in in itself known manner and function housed one or more piston rings 54. The combustion chamber 15 is limited in a known manner by the piston surface 52, the cylinder wall 3 and a piston cover 52 opposite, not shown cylinder cover.

The cylinder wall 3 comprises one or more recesses 6, in which recesses 6 preferably each a lubricant nozzle 7 for applying lubricant 8 is accommodated on the running surface 2. In a preferred embodiment, the lubricant nozzles 7 are arranged along a circumferential line of the cylinder 4, preferably (but not necessarily) at equidistant intervals, wherein the area enclosed by the peripheral line is perpendicular to the cylinder axis 10 extending along the cylinder 4. In this case, the lubricating system 1 may comprise a plurality of lubricant nozzles 7, which are arranged along one or more parallel circumferential lines. The lubricant nozzle 7 is housed sunk in the cylinder wall 3 in the recess 6, that the piston can pass through the recess 6 during its movement without obstruction. In the in Fig. 1 In the exemplary embodiment shown, the cylinder wall 3 has at least one groove 11 running in the circumferential direction for storing the lubricant 8 applied to the running surface 2, whereby a plurality of grooves 11 may be advantageous. In this case, the groove 11 in a closed line, for example in the form of a circular line around the entire circumference of the cylinder wall 3 extend. It is also conceivable that the groove 11 has one or more separate sections which do not extend in the form of a closed curve over the entire circumference of the cylinder wall 3.

The lubricant 8, which can be applied to the running surface 2 by the lubricant nozzles 7, can be fed to each lubricant nozzle 7 through a separate feed line 12.

In operation of the reciprocating internal combustion engine, the piston 5 moves in a known manner between a moderately upper reversal point OT and a lower illustration point reversal point UT that the surface 52 of the piston 5 in its movement between the lower and upper reversal point in each case at least one recess 6 of the cylinder wall. 3 and / or at least one groove 11 so happens that at least one recess 6 of the cylinder wall 4 and / or at least one groove 11 is temporarily completely covered by the side surface 53 of the piston 5. Preferably, the position of all the recesses 6 in the cylinder wall 3 and / or all grooves 11 can be selected so that when the piston is at the lower reversal point UT, all the recesses 6 in the cylinder wall 3 and / or all grooves 11 in connection to the combustion chamber 15 stand, and when the piston is in the position of the upper reversal point OT, all the recesses 6 in the cylinder wall 3 and / or all grooves 11 with the interior of the cylinder 4 below the piston 5 are in communication.

Fig. 2 shows in a section along the line A - A according to Fig. 1 a cylinder 4, comprising an embodiment of a lubrication system with lubricant nozzle 7, metering unit 13 and control device 14. The lubricant 8 can be supplied to the lubricant nozzle 7 by means of a feed line 12 from a metering unit 13, which in turn is supplied via a supply line 131 centrally with lubricant 8. Preferably leads from the metering unit 13 to each lubricant nozzle 7 a separate line, so that the supply of lubricant 8 to each lubricant nozzle 7 depending on various operating parameters of the reciprocating internal combustion engine, such as the speed, the load, the cylinder temperature or other operating parameters is individually adjustable. Of course, the supply of lubricant 8 to the lubricant nozzles 7 can also take place independently of the operating parameters of the reciprocating internal combustion engine according to a predeterminable scheme. In particular, it is also conceivable that one or more of the lubricant nozzles 7 are connected via a common feed line 12, for example in the form of a common rail system, for supplying the lubricant 8 with the metering unit 13. The lubricant 8 is supplied to the lubricant nozzle 7 via the supply line 12 at a prescribable working pressure. The lubricant nozzle 7 preferably has a valve 72, for example a valve 72 spring-loaded in a known manner. In this case, the valve 72 is adjustable so that it spontaneously opens under the action of the working pressure of the pending in the supply line 12 lubricant 8, so that the lubricant 8 from the supply line 12 flow into the lubricant nozzle 7 and the impulse-like running surface can be fed through the outlet opening. The supply line 12 can also be protected against or in the lubricant nozzle 7 by a check valve 73 against cylinder-side overpressure. Preferably, the valve 72 is designed so that it simultaneously fulfills its function as a check valve 73.

Preferably, the metering unit 13, which may also be equipped with a check valve, not shown, with respect to the supply line 12, so controlled or regulated by means of a programmable control device 14 that the amount and / or the time of each lubricant nozzle 7 supplied lubricant 8 in Dependence on different operating parameters, such as from the speed, the load, the cylinder temperature or other operating parameters is adjustable. Also, for example, the quality of lubricant 8 and / or the quality of the fuel or other fuels can determine both the time, as well as the amount of the supplied lubricant 8 with. The operating parameters can be read in by sensors, which are not shown here, and fed via data lines 141 to the freely programmable drive device 14, which controls or regulates the metering device correspondingly via a communication line 142.

In Fig. 3 is shown in a schematic manner, as the lubricant jet 9 is applied to the tread 2. The lubricant nozzle 7 has an outlet opening 71 which is designed so that the lubricant 8 emerges in a compact lubricant jet 9, ie that atomization of the lubricant jet 9 through the lubricant nozzle 7 is largely avoidable. A sputtering in the scavenging air and / or in a gas which is located in the cylinder is largely avoided. Instead, the lubricant 8 is applied directly to the running surface in pulsed fashion in a compact jet. The recess 6 is designed as an oblique groove so that the emerging from the outlet opening 71 lubricant jet 9 with respect to the tread 2, in a substantially tangential direction, so in the combustion chamber 15 exits that on the lying in the direction of the lubricant jet 9 portion 91st the tread 2 lubricant 8 is applied directly. The partial region 91 extends, for example, from the outlet opening 71 to or approximately up to a further circumferential recess 6 in the circumferential direction, so that the running surface 2 can be acted upon with lubricant 8 in the circumferential direction, in a region determinable by the geometry of the lubricant jet 9. Each lubricant nozzle 7 can be in the recess 6 of the cylinder wall 3 may be arranged such that the lubricant jet 9 emerges from the lubricant nozzle 7 substantially tangentially but at an angle which can be predetermined in each case to the cylinder axis 10. This makes it possible to apply the Schiermittelstrahl 9 in the circumferential direction of the cylinder 4 spirally in one of the two directions of the cylinder axis 10 on the tread 2. Of course, the lubricant jet 9 also emerge perpendicular to the cylinder axis 10 and substantially in tangentilaer direction, so that the lubricant 8 can be applied to the running surface 2 largely in a plane in the circumferential direction, that is not spirally.

The lubricant jet 9 is either before and / or during and / or after the piston passes the recess 6, impulsively applied to the tread 2 through the lubricant nozzle 7 and by the movement of the piston 5 and the piston rings 54 both in the circumferential direction and in axial direction on the tread 2 of the cylinder wall 3 additionally evenly distributed. By means of a corresponding control or regulation by the drive unit 14, both the quantity and the time of the lubricant delivered to each lubricant nozzle 7 can be optimized by means of the metering unit 13. To minimize the amount of lubricant 8 used, the supply of lubricant 8 to the tread 2, e.g. also be omitted for one or more cycles of the reciprocating internal combustion engine, whereby the consumption of the lubricant used 8 can be further reduced. The cylinder wall 3 may have one or more circumferentially extending grooves 11 in which a portion of the applied lubricant 8 can be stored. For example, by the piston rings 54, a portion of the lubricant 8, which is located on the tread 2, stripped into the groove 11 and stored, from which groove 11, the lubricant 8 at a later time back to the tread 2 and so again for Can contribute lubrication, a process that also contributes significantly to the saving of lubricant 8.

The arrangement and configuration, in particular the lubricant nozzles of the inventive lubricating system ensures that the lubricant is applied directly to the running surface of the cylinder wall of the cylinder of the reciprocating internal combustion engine. In this case, the inventive lubricating system is characterized by its particularly simple structure, in particular the lubricant nozzles, which can be dispensed with costly additional equipment parts, such as on leak oil lines or the like, due to their simple Konstruktuion. It has been found that this results in a significantly more uniform lubricant application compared to the prior art, ie. means that the lubricant is optimally distributed both in the axial direction and in the circumferential direction on the running surface of the cylinder, whereby the wear of the running surface of the cylinder or the piston is significantly reduced. The fact that the lubricant is applied directly to the tread and not via an intermediate step, such as by atomization of the lubricant jet in the scavenging air, a particularly economical and efficient use of the lubricant used is guaranteed.

Claims (1)

1. A method of lubricating a running surface of a cylinder wall (3) of a cylinder (4) of a reciprocating internal combustion engine, in particular of a two stroke large diesel engine with longitudinal scavenging, in which cylinder (4) a piston (5) is moved to and fro along the running surface (2), with lubricant (8) being applied to the running surface (2) through at least one lubricant nozzle (7) arranged in a recess (6) of the cylinder wall (3),
   characterised in that
   the lubricant (8) is applied direclty to the running surface (2) of the cylinder wall (3) in a substantially tangetial direction with respect to the running surface (2 through a plurality of discharge openings (71) of the lubricant nozzle (7) and through an oblique groove of the recess (6) in a plurality of compact lubricant jets (9) and an atomisation of the lubricant jets (3) by the lubricant nozzle (7) is very largely avoided.

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