EP2682572B1 - Lubricant system - Google Patents

Description

The invention relates to a lubrication system for a piston-cylinder unit according to the preamble of claim 1. The invention further relates to an internal combustion engine, in particular a large engine with a piston-cylinder unit with a lubrication system.

Large engines, especially in the design as large diesel engines, which may be configured as two-stroke or four-stroke internal combustion engines, are often used as drive units for ships or in stationary operation, e.g. used to drive large generators for generating electrical energy. The large engines usually run for long periods in continuous operation, which places high demands on the reliability and availability. Therefore, for the operator in particular long maintenance intervals, low wear and an economical handling of the operating materials are central criteria.

In the operating state, the piston slides along the surface of the wall of the cylinder serving as a running surface, which is usually designed in the form of a cylinder liner, which is also referred to as a cylinder liner. In this case, a cylinder or piston lubrication is provided. On the one hand, the piston must slide as smoothly as possible, that is unhindered, in the cylinder, on the other hand, the piston must seal the combustion chamber in the cylinder as well as possible in order to ensure efficient conversion of energy released during the combustion process into mechanical work.

Therefore, during operation of the large diesel engine, usually a lubricant, usually in the form of a lubricating oil, is introduced into the cylinder in order to achieve good running characteristics of the piston and to minimize the wear of the running surface, the piston and the piston rings. Furthermore, the lubricating oil is used to neutralize aggressive combustion products and to prevent corrosion. Because of these many requirements, very high quality and expensive substances are often used as lubricants.

There is therefore a need for a particularly efficient and economical operation of the engine to work with the lowest possible lubricant consumption. Lubricant consumption is the amount of lubricant understood that is no longer available for the actual lubrication task, ie by the lubrication process is consumed, so lost. This loss may be due to the fact that the lubricant is taken up as droplets in the fuel gas or distributed as a lubricant film along the cylinder inner wall. This lubricant can therefore enter the combustion chamber in gaseous form or liquid form, ignite there and be burned, an effect which is undesirable in itself, because it can lead to misfires or deposits in the cylinder interior.

A proven lubrication method is the so-called internal lubrication, in which the lubricant is conveyed through the interior of the piston and then applied via one or more lubrication points, which are provided on the surface of the piston from the piston inner to the piston or on the cylinder surface. Such a method is used, for example, in EP-A-0 903 473 disclosed.

There are a variety of ways known to supply lubricant to a cylinder inner wall of a reciprocating internal combustion engine. For example, the documents show EP2133520 A1 such as EP2253810 A1 Lubricating devices with lubricant reservoirs, which are arranged in the piston itself. These solutions therefore concern the supply of lubricant to the lubrication point via the piston.

In order to reduce the lubricant requirement, various approaches have been taken. On the one hand, an oil collection ring may be provided, as he, for example, from the EP2133520 A1 or from the EP 1 936 245 A1 is known. That is, by means of an oil collection ring can be avoided that lubricant enters the combustion chamber.

Alternatively or in addition to this, the sliding surface of the piston in the cylinder interior and lubricant can also be supplied via the cylinder liner itself and are also recorded in the cylinder liner itself in recesses, as for example in the EP 20 50 946 A1 are disclosed.

The cylinder lubrication of two-stroke marine diesel engines is carried out by the metered injection of lubricant, the current standard lubrication systems inject only about every tenth revolution due to the constant-volume pump, which is unfavorable for the distribution of the lubricant. Also, the relatively long lines between the pump and injector reduce the dynamics of the system, that is, the amount of time that a metering pulse takes to cover the distance from the pump to the lubricant injector is too long to provide precise control over the injection timing Allow pump. In addition, with the increasing length of the connecting lines losses due to pipe friction increase, so that by the elasticity of the lubricant by its compressibility in the connecting lines no pulse more detectable at the entrance of the lubricant injection valve.

The WO0235068 A1 shows a fluid agent actuated lubricant injection element. For the control of the lubricant injection in this case, a sufficiently high fluid pressure must be available. Furthermore, provision must be made for the pressurized fluid and the lubricant to flow in separate channels. This fluid fluid pressure is generated according to this embodiment with a mounted on the lubricant injection pump, which is driven by a separate motor. According to this solution, therefore, one pump and one motor are required for each lubricant injection element. Therefore, if a plurality of lubricant injection elements are provided, this solution results in increased maintenance and increased investment costs. Therefore, this solution may be unsuitable for use in multi-cylinder engines, especially in large marine engines. On the one hand, the maintenance effort must be as low as possible, since the engines must run in continuous operation over the entire journey time of the ship. That is, for redundancy reasons, a plurality of such fluid agent actuated lubricant insert elements would have to be kept redundant in stock. On the other hand, the investment costs should be kept as low as possible.

One way to dispense with a variety of pumps and motors, provides the use of a so-called common rail system for providing the lubricant to the lubricant injection elements. The WO2011116768 A1 shows such a common rail system for the injection of lubricant in a plurality of cylinders of an internal combustion engine. In this system, the problem of connecting lines described earlier is solved such that the metering of the lubricant takes place directly in the lubricant element via solenoid-controlled valves. By means of these solenoid-controlled valves, the supply of lubricant can be controlled very accurately, both the time of supply of lubricant to the cylinder, and thus the duration of the supply of lubricant, that is, the amount of lubricant to be supplied to the lubrication point. However, must be ensured by the magnet-controlled valves to be used for this purpose that the supply of lubricant can be initiated by opening the connection to the lubricant nozzle, but also that the supply of lubricant can be interrupted again. Depending on the lubricant pressure, the interruption of the lubricant supply may take a different amount of time until the closing pressure is reached, that is to say the lubricant volume which reaches the lubricating point is greater than that provided by the regulation. It is of course possible to set a pressure-dependent switching behavior of the solenoid-controlled valve, but this means an increased control effort. Of course, possible to set a pressure-dependent switching behavior of the solenoid-controlled valve, but this means an increased control effort.

Also shows the US 3,958,725 a fluid agent actuated lubricant injection element. The lubricant injection element has an inlet opening, via which the lubricant is supplied and an outlet opening, via which the lubricant is discharged. The outlet opening can be closed by a ball check valve, whereby the ball check valve can be moved by means of the pressure of the lubricant in such a way that the outlet opening can be released for the delivery of lubricant.

It is therefore an object of the invention to reduce the regulatory effort for the dosage of lubricant.

A further object of the invention is to ensure a precise metering of the lubricant for the lubrication of a sliding surface for a piston along a cylinder inner wall.

Another object of the invention is to reduce lubricant consumption.

Another object of the invention is to adapt the lubricant requirement to the operating state of the internal combustion engine.

These objects of the invention are achieved by means of a lubricant injection element according to claim 1. The subclaims contain further advantageous embodiments of the invention.

The lubricant injection element has a housing element, an inlet opening for a lubricant which is arranged in the housing element and a storage element which is in fluid-conducting connection with the inlet opening and is arranged in the interior of the housing element. The storage element has a chamber, which is designed to receive lubricant, and an outlet opening, which can be closed by means of a shut-off element. The shut-off element is movable by means of an actuating element such that the outlet opening is releasable for dispensing lubricant.

This allows a very compact design of the lubrication system. Furthermore, it can be ensured by this arrangement that the dosage is triggered immediately when a lubricant requirement is signaled.

A throttle element may be disposed between the inlet port and the storage element, whereby one in the short period of time between completion of the Emptying the memory and closing the solenoid valve escaping lubricant amount is reduced to a non-relevant amount. Alternatively, instead of the throttle element, at least one further solenoid valve can be used, to which no special requirements are made with regard to dynamics, since the lubricant supply can be interrupted long before the start of the injection process and reopened long after its completion. As a further alternative, the solenoid valve may be extended for injection to a multiway valve or replaced with a multiway valve. According to one embodiment, the chamber may have a displacement element, so that the volume of the chamber is variable. In particular, the lubricant injection element may include a needle valve.

A lubricating system for a piston-cylinder unit for an internal combustion engine, in particular a large engine or compressor comprises a pump, a lubricant injection element, a connecting line between the pump and the lubricant injection element for supplying lubricant to the lubricant injection element. Between the pump and the lubricant injection element, a storage element is provided in the connection line.

The storage element is advantageously located at a short distance from the lubricant injection element, may even be integrated into the lubricant injection element. The storage element contains a defined volume of lubricant. The end of the injection process is thus predetermined by the emptying of the storage element. Thus, according to the inventive solution, only the beginning of the injection of lubricant must be regulated, but not its end. Therefore, it is not necessary for the lubricant injection element to have a device that interrupts the flow of lubricant. Even a leakage of lubricant can not occur with the inventive solution.

Therefore, the solution according to the invention results in a simplification of the metering of lubricant, in particular for a piston-cylinder unit of an internal combustion engine, in particular for a large engine.

In particular, the volume to be metered per stroke when the storage element is completely filled can be in the range from 0.03 to 0.5 cm ³ , depending on the type of internal combustion engine.

The lubrication rate can be in the range of 0.2 to 2.5 g / kWh. The number of injection elements per cylinder can be between 1 and 24, in particular from 4 to 24. There can be between 0.3 and 3 injections of lubricant per stroke.

Memory elements may be connected in series with each other or may be connected in parallel with each other.

Furthermore, a common storage element may be provided for a plurality of lubricant injection elements. Alternatively or in addition thereto, a single or a plurality of lubricant injection elements may be connected to a plurality of storage elements. The storage elements may have chambers that have a different volume and / or the volume of each storage element may be variable. The connecting line may contain at least one throttle element between the pump and the storage element. The throttle element may have at least one adjusting element for changing the flow cross-section. By means of the adjustable throttle element can thus be adjusted, the filling speed of the memory element.

According to one embodiment, the pump may have an adjusting means to change the flow rate per unit time. In particular, the pump may be designed as a variable-speed gear pump or a piston pump with controllable stroke.

In one embodiment, the lubricant injector may include the storage element. This embodiment allows a very compact design of the lubrication system. Furthermore, it can be ensured by this arrangement that the dosage is triggered immediately when a lubricant requirement is signaled. In particular, the lubricant injection element has a housing element, an inlet opening for a lubricant which is arranged in the housing element and the storage element which is in fluid-conducting connection with the inlet opening and is arranged in the interior of the housing element. The storage element has a chamber, which is designed to receive lubricant, and an outlet opening, which can be closed by means of a shut-off element. The shut-off element is movable by means of an actuating element such that the outlet opening is releasable for dispensing lubricant.

A throttle element may be disposed between the inlet port and the storage element, thereby reducing an amount of lubricant exiting in the short time period between completion of emptying of the accumulator and closure of the solenoid valve to a non-relevant amount. Alternatively, instead of the throttle element, at least one further solenoid valve can be used, to which no special requirements are made with respect to dynamics, since the lubricant supply interrupted long before the start of the injection process and long Furthermore, a common storage element may be provided for a plurality of lubricant injection elements. Alternatively or in addition thereto, a single or a plurality of lubricant injection elements may be connected to a plurality of storage elements. The storage elements may have chambers that have a different volume and / or the volume of each storage element may be variable. The connecting line may contain at least one throttle element between the pump and the storage element. The throttle element may have at least one adjusting element for changing the flow cross-section. By means of the adjustable throttle element can thus be adjusted, the filling speed of the memory element.

According to one embodiment, the pump may have an adjusting means to change the flow rate per unit time. In particular, the pump may be designed as a variable-speed gear pump or a piston pump with controllable stroke.

An internal combustion engine may include a lubrication system according to any one of the preceding embodiments. The internal combustion engine comprises a piston-cylinder unit, the piston-cylinder unit comprises a cylinder and a piston, wherein the cylinder has a cylinder jacket which delimits a cylinder interior. The cylinder jacket contains at least one lubricant injection element according to one of the preceding embodiments.

The method for lubricating a piston-cylinder unit of an internal combustion engine comprises a piston-cylinder unit. A lubrication point of the piston-cylinder unit, a lubricant is supplied by means of a lubrication system. The lubrication system includes a pump, a lubricant injector, a connection line between the pump and the lubricant injector for supplying lubricant to the lubricant injector. Between the pump and the lubricant injection element, a storage element is provided in the connection line. The lubricant is conveyed by the pump into the connecting line and into the storage element, from the storage element, the lubricant is conveyed via the lubricant injection element to the lubrication point until the storage element is at least partially emptied.

In particular, the lubricant injection element has an actuating element, which releases an outlet opening in the housing element of the lubricant injection element, so that lubricant reaches the lubricating point.

The lubricant injection element contains a throttle element, which is arranged between the inlet opening and the storage element, so that the storage element is filled up again after at least partial emptying. Advantageously, the time duration of the filling over the delivery rate of the pump can be regulated.

The above description as well as the embodiments serve only as an example for explaining the operation of the invention. Further advantageous embodiments will become apparent from the dependent claims and the drawings. In addition, in the context of the present invention, individual features from the embodiments described or shown can be combined with one another as desired.

The invention will be explained in more detail with reference to the accompanying drawings.

• Fig. 1 einen Schnitt durch eine Kolben-Zylindereinheit sowie das Schmiersystem nach einem ersten erfindungsgemässen Ausführungsbeispiel,
• Fig. 2 eine Grafik des Drucks in Abhängigkeit vom Volumen (p-V Diagramm),
• Fig. 3 einen Schnitt durch ein Ausführungsbeispiel eines Schmiermitteleinspritzelements,
• Fig. 4 ein Schmiersystem nach einem zweiten Ausführungsbeispiel.

Show it

• Fig. 1 a section through a piston-cylinder unit and the lubrication system according to a first inventive embodiment,
• Fig. 2 a graph of the pressure as a function of the volume (pV diagram),
• Fig. 3 a section through an embodiment of a lubricant injection element,
• Fig. 4 a lubrication system according to a second embodiment.

In Fig. 1 the structure of the proposed lubrication system is shown schematically. A controllable pump 1, for example a variable-speed gear pump or piston pump with controllable stroke, conveys the lubricant into a connecting line 2, to which all lubricant injection elements 6 are connected. Of course, only a single lubricant injection element 6 may be provided, but it may also be present a variety of lubricant injection elements. The lubricant injection element or elements 6 are arranged on the cylinder wall or the cylinder liner. The delivery pressure is selected as a function of the desired injection quantity of lubricant. The lubricant is conveyed through a throttle element 3 into one or more storage elements 4. The storage element 4 may be designed, for example, as a piston accumulator element or as a pneumatic storage element. The injection process is triggered by a shut-off, such as a solenoid valve 5. When the solenoid valve is open, the needle valve of the lubricant injection element 6 is opened, so that the lubricant at the lubrication point in the space between the cylinder 20 and piston 11 can flow and from there to the lubrication point on the cylinder inner wall or on the piston ring. The injection process ends, limited. The piston 11 has a piston skirt surface 35, a piston top side 36 and a piston bottom 37. The piston skirt surface 35, the piston top side 36 and the piston bottom 37 define a piston body 25. The piston body 25 may consist of several parts, for example comprising a piston head 38 and a piston skirt 39. The piston body 25 may be at least partially provided with a cavity 40, through which a coolant can be introduced into the piston body 25. A groove 12 is formed in the piston skirt surface 35, via which a lubricant can be added to the sliding pair of cylinder inner wall and piston ring or can be withdrawn from the surface of the cylinder inner wall. Through the groove 12, a gap 16 between the piston skirt surface 35 and cylinder shell 17 is formed. The groove 12 may extend over part of the circumference of the skirt surface 35. In particular, a plurality of such grooves may be provided on the circumference of the piston skirt surface, which is not shown in the drawing.

The cylinder 20 has a cylinder jacket 17, which contains a plurality of flushing openings 19. The cylinder 20 has a cylinder head 21 with an inner side 22, to which the cylinder jacket 17 adjoins, wherein from the piston top, the cylinder jacket 17 and the inner side 22 of the cylinder head 21, a combustion chamber 23 is limited. A flushing chamber 24 adjoins the piston bottom 6, wherein the fluid pressure in the interior of the recess 11 is smaller than the pressure in the combustion chamber and smaller than the pressure in the washing chamber 24.

A first piston ring 14 and a second piston ring 15 are each arranged on the piston skirt surface 35, so that a piston chamber 14, the piston skirt surface 35 and the cylinder jacket 17 limited space 16 is formed, which includes a groove 12. In particular, a plurality of such grooves may be provided parallel to each other on the circumference of the piston skirt surface, which is not shown in the drawing. The piston ring 14 forms a substantially gas-tight connection to the combustion chamber 23. The piston ring 15 has no gas-tight design. It can also be designed as a lubricant wiper ring.

Fig. 2 shows a possible characteristic of the lubrication system. The volume is entered on the x-axis and the injection pressure on the y-axis. This characteristic relates to a storage element with two spring elements. Depending on the spring stiffness, the bias voltage and / or the direction of action of a stop, the relationship between the injection pressure and the stored volume can be influenced. In the pressure range, which is between P ₀ 8 and P _n 9, only one spring element is stretched. At the point corresponding to P _n 9, the piston moves to a stop which is a second, For example, coaxially arranged, that is parallel connected spring element entrains. This creates a so-called progressive characteristic, which means that as the volume increases, the pressure increases disproportionately. In principle, it is also possible to produce a degressive characteristic with two spring elements, for example by connecting the spring elements in series and using a stop between the spring elements. A degressive characteristic may be advantageous to keep the pressure change during the injection small.

Fig. 3 shows a section through an embodiment of a lubricant injection element 6. The lubricant injection element 6 has a housing member 26 in which an inlet opening 27 is arranged for the lubricant, which passes from the pump via a connecting line to the lubricant injection element 6. The inlet opening 27 is arranged in the housing element 26, which is optionally formed in several parts. Furthermore, a storage element 4, which is in fluid-conducting connection with the inlet opening 27 and is arranged in the interior of the housing element 26, is located in the housing element 26. The storage element 4 has a chamber 28, which is designed to receive lubricant, and an outlet opening 30, which can be closed by means of a shut-off element 31. The shut-off element 31 is movable by means of an actuating element 32 such that the outlet opening 30 can be released for dispensing lubricant. Of course, a plurality of outlet openings 30 may be provided.

A throttle element 3 is arranged between the inlet opening 27 and the storage element 4. The throttle element 3 is formed as a channel in the housing element, which extends partially annular. Of course, the throttle element could also have a different shape than those in Fig. 3 have shown shape. The storage element 4 has a sliding element 29 protruding into the chamber 28, which can be moved back and forth in the chamber 28, so that the volume of the chamber 28 can be changed. The displacement element 29 is by a spring element 33 in his in the Fig. 3 shifted lowest position. In this position, the volume of the chamber 28 is the smallest. If the internal pressure of the lubricant in the chamber 28 is greater than the pressure exerted by the spring element 33 on the displacement element 29, the displacement element 29 moves against the spring force of the spring element 33 upwards. When the pressure becomes too high, an outlet opening 42 is released by the displacement element 29, so that the lubricant injection element also has a safeguard against overpressure.

If the displacement element 29 is at the upper stop, excess lubricant is drawn off via the leakage opening 41 in order to allow rapid movement of the displacement element 29. In this case, the lubricant that passes through the leakage opening can be detected by a detection mechanism, so that a leakage of the system can be detected and, if necessary, an alarm can be triggered.

As an alternative to a leakage opening 41, the displacement element in the region of the receptacle of the spring element can not be designed as a piston, but a gap between the displacement element and the housing remain, which is not shown in the drawings. During normal operation, the displacement element 29 should not reach the stop, i. do not completely compress the spring 33. The filling process is limited by the equilibrium of forces between the spring element 33 and the displacement element 29 designed as an annular piston.

Fig. 4 shows a lubrication system according to a second embodiment, which differs from the embodiment according to Fig. 1 differs in that a second memory element 44 is provided in addition to the memory element 4. The first memory element 4 is arranged in a parallel arrangement to the second memory element 44. According to this embodiment, both memory elements are filled at the same time. Of course, the filling or emptying of one of the storage elements with respect to the other can be accelerated or delayed by the use of different spring stiffnesses. Alternatively, the storage element 4 may be arranged downstream of the storage element 44 in the flow direction. In this case, first the storage element 44 is filled before the filling of the storage element 4 takes place. For each of the two storage elements, a separate shut-off, such as a solenoid valve should be provided. The arrangement may be advantageous if very different operating conditions must be covered.

Claims (15)

1. A lubricant injection element (6) including a housing element (26), an inlet opening (27) for a lubricant which is arranged in the housing element (26) and a storage element (4) which is in fluid-conductive communication with the inlet opening (27) and is arranged in the interior of the housing element (26), wherein the storage element (4) has a chamber (28) which is configured for receiving lubricant and has an outlet opening (30) which can be closed by means of a shut-off element (31), with the shut-off element (31) being movable by means of an actuation element (32) such that the outlet opening (30) can be released for dispensing lubricant.
2. A lubricant injection element (6) in accordance with claim 1,
   wherein a restrictor element (3) is arranged between the inlet opening (27) and the storage element (4).
3. A lubricant injection element (6) in accordance with one of the preceding claims 1 or 2, wherein the chamber (28) has a displacement element (29) so that the volume of the chamber (28) is variable.
4. A lubrication system for a piston-in-cylinder arrangement (10) for an internal combustion engine, in particular for a large engine or for a compressor, including a pump (1), a lubricant injection element (6) in accordance with anyone of claims 1 to 3 and a connection line (2) between the pump and the lubricant injection element (6) for supplying the lubricant injection element (6) with lubricant, characterized in that a storage element (4, 44) is provided in the connection line (2) between the pump (1) and the lubricant injection element (6).
5. A lubrication system in accordance with claim 4, wherein a restrictor element (3) is arranged between the pump (1) and the lubricant injection element (6).
6. A lubrication system in accordance with any one of the preceding claims 4 or 5, wherein the storage element (4, 44) contains a chamber for receiving a quantity of lubricant which corresponds to the maximum requirement at the lubrication site.
7. A lubrication system in accordance with any one of the preceding claims 4 to 6, wherein a plurality of storage elements (4, 44) are arranged behind one another or next to one another.
8. A lubrication system in accordance with any one of the preceding claims 5 to 7, wherein the restrictor element (3) has an adjustment element for varying the throughflow cross-section.
9. A lubrication system in accordance with any one of the preceding claims 4 to 8, wherein the pump (1) has a setting means to vary the conveying quantity per unit of time.
10. A lubrication system in accordance with any one of the preceding claims 4 to 9, wherein the lubricant injection element (6) contains the storage element (4).
11. An internal combustion engine including a lubrication system in accordance with anyone of claims 4 to 10, wherein the internal combustion engine includes a piston-in-cylinder arrangement (10), wherein the piston-in-cylinder arrangement (10) includes a cylinder (20) and a piston (11), wherein the cylinder (20) has a cylinder jacket (17) which bounds an inner cylinder space (18) and wherein the cylinder jacket contains at least one lubricant injection element (6) in accordance with any one of the claims 8 to 10.
12. A method of lubricating a piston-in-cylinder arrangement (10) of an internal combustion engine, wherein a lubricant is supplied to a lubrication site of the piston-in-cylinder arrangement (10) by means of a lubrication system in accordance with anyone of claims 4 to 10, wherein the lubrication system includes a pump (1), a lubricant injection element (6), and a connection line (2) between the pump (1) and the lubricant injection element (6) for supplying the lubricant injection element (6) with lubricant, wherein a storage element (4, 44) is provided in the connection line (2) between the pump (1) and the lubricant injection element (6), wherein the lubricant is conveyed by the pump (1) into the connection line (2) and into the storage element (4) and wherein the lubricant is conveyed to the lubricant site via the lubricant injection element (6) for so long until the storage element (4) is at least partly emptied.
13. A method in accordance with claim 12, wherein the lubricant injection element (6) has an actuation element (32) which releases an outlet opening (30) in the housing element (26) of the lubricant injection element (6) so that lubricant reaches the lubrication site.
14. A method in accordance with one of the claims 12 or 13, wherein the lubricant injection element (6) contains a restrictor element (3) which is arranged between the inlet opening (27) and the storage element (4) so that the storage element (4) is topped up again after at least part emptying.
15. A method in accordance with any one of the claims 12 to 14, wherein the duration of the topping up is regulated via the conveying rate of the pump (1).

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