CN117211951A

CN117211951A - Crosshead type large-sized turbocharged two-stroke single-flow internal combustion engine

Info

Publication number: CN117211951A
Application number: CN202310656050.4A
Authority: CN
Inventors: 雅维耶·布拉斯克斯·莫雷诺
Original assignee: Mannone Solutions Mannone Solutions Germany Branch
Current assignee: Mannone Solutions Mannone Solutions Germany Branch
Priority date: 2022-06-10
Filing date: 2023-06-05
Publication date: 2023-12-12
Also published as: DK181438B1; DK202270305A1; KR20230171389A; JP2023181120A

Abstract

A large turbocharged two-stroke, single flow internal combustion engine (100) of the crosshead type has a telescopic tube (30) mechanically connected to the cylinder frame (23) and the crosshead (9) and connecting a source of pressurized lubrication and cooling medium to the crosshead (9), the piston rod (15) and a conduit (36) in the piston (10) for cooling the piston (10).

Description

Crosshead type large-sized turbocharged two-stroke single-flow internal combustion engine

Technical Field

The present disclosure relates to a large turbocharged two-stroke internal combustion engine of the crosshead type, comprising at least one cylinder in which a reciprocating piston is received, which piston is cooled by a flow of cooling medium supplied to the piston via a telescopic tube connecting the cylinder frame with the crosshead.

Background

Large turbocharged two-stroke internal combustion engines are commonly used in propulsion systems for large vessels or as prime movers in power plants. The vast size, weight and power output of large turbocharged two-stroke internal combustion engines makes them quite different from conventional combustion engines and makes large two-stroke turbocharged compression-ignition internal combustion engines self-contained. The height of these engines is generally not critical and therefore these engines are built with crossheads to avoid lateral loads on the pistons. Typically, these engines operate using natural gas, petroleum gas, methanol, ethane, or fuel oil.

Large turbocharged two-stroke internal combustion engines may operate with compression ignition, i.e. on the Diesel principle, or may operate as premixed engines, i.e. on the Otto (Otto) principle, wherein the scavenging gas is mixed with fuel during the piston stroke from Bottom Dead Center (BDC) to Top Dead Center (TDC).

The piston is typically made of heat resistant steel to ensure that the piston can withstand the high temperatures in the combustion chamber. Furthermore, the piston is cooled by a cooling medium, such as lubricating oil, to prevent overheating of the piston during engine operation.

An engine lubrication system provides lubrication medium to various components of an engine. The lubricating medium also serves to cool the piston. Typically, the medium used is lubricating oil.

The branching of the lubrication system is connected to the crosshead by means of a telescopic tube, the lubrication and cooling medium thus having a number of functions, including: travels up the piston rod to cool the piston and then travels down and lubricates the crosshead bearings and guide shoes that guide the crosshead between the vertical guide plates. A part of the telescopic tube is connected to the crosshead and another part of the telescopic tube is connected to the cylinder frame or through the cylinder frame to the inlet manifold, whereby the inner cavity of the telescopic tube is used for transporting cooling medium from the connection point at the cylinder frame to the piston via the crosshead and the tubing in the piston rod. The telescoping tube includes an outer tube, wherein the inner tube is at least partially received in the lumen of the outer tube. The inner tube may be moved in a translational manner to follow the reciprocating movement of the crosshead relative to the cylinder frame.

JPS57176616U discloses a large turbocharged two-stroke uniflow internal combustion engine of the crosshead type having: a bellows fluidly connecting a source of cooling and lubricating liquid to an inlet port on the crosshead; and a valve that allows cooling and lubricating medium to flow from the cooling and lubricating liquid source to the bellows and prevents cooling and lubricating medium from flowing from the bellows to the cooling and lubricating liquid source. The valve includes a resilient member biasing the valve member toward the seat.

Disclosure of Invention

It is an object of the present invention to provide a large turbocharged two-stroke uniflow internal combustion engine of the crosshead type with improved piston cooling.

Experiments and simulations performed by the inventors show that the cooling of the piston fluctuates greatly during the engine cycle, and that a major part of the cooling occurs during a relatively small part of the engine cycle. Through further testing and simulation, the inventors have found that: such fluctuations are caused by pressure and flow fluctuations of the cooling medium to the piston. Further analysis and insight indicate that these pressure and flow fluctuations are caused by extension and retraction of the bellows during the engine cycle.

According to a first aspect, there is provided a large turbocharged two-stroke uniflow internal combustion engine of the crosshead type, comprising:

at least one cylinder liner having a scavenge port at a lower end of the cylinder liner and a drain valve at an upper end of the cylinder liner,

a reciprocating piston in at least one cylinder liner, the reciprocating piston being connected to the reciprocating crosshead by a piston rod,

with a source of pressurized cooling and lubricating medium,

a bellows fluidly connecting the source to an inlet port on the crosshead,

a conduit extending from the inlet port to the piston, preferably through the cross-head and the piston rod, and

a valve configured to: allowing cooling and lubricating medium to flow from the source to the bellows and preventing or limiting cooling and lubricating medium flow from the bellows to the source,

the valve comprises a movable valve member arranged to be movable between a closed or restricting position on the first seat and an open position on the second seat, and the movable valve member is biased to the open position by gravity only.

By providing a check valve or a valve like a check valve upstream of the bellows or at the inlet of the bellows, a reverse flow of the cooling medium during the compression stroke of the piston (from BDC to TDC), i.e. when the bellows is contracted, can be avoided or at least reduced, thereby ensuring a more stable flow of the cooling medium to the piston throughout the engine cycle. The inventors have found that: closing or restricting the check valve ensures that the flow of cooling medium is increased, because the bellows acts as a positive displacement pump if backflow from the bellows to the source is prevented or restricted when the bellows is contracted (compression stroke of the piston). Increasing the cooling capacity by extending the duration of active cooling, and the resulting substantial increase in the flow of cooling medium throughout the engine cycle, improves cooling of the piston, the valve comprising a movable valve member arranged to be movable between a closed or restricting position on the first seat and an open position on the second seat, and the movable valve member being biased to the open position by gravity only.

Improved piston cooling may be used to achieve reduced piston temperatures, which may provide lower cost by using a lower temperature resistant steel type for the piston, thereby providing increased piston ablation margin and allowing more freedom in the layout of the fuel valve atomizer, particularly towards the piston.

By using a valve having a first seat associated with the closed position of the valve member and a second seat associated with the open position of the valve member, and by the valve member being biased towards the second seat, i.e. the closed position, by gravity alone, a significantly more reliable valve can be obtained compared to prior art resilient member biased valve members which are prone to failure.

According to a possible implementation manner of the first aspect, the at least one cylinder liner is supported by the cylinder frame, and the telescopic tube comprises: a stationary tube physically connected to the cylinder frame; and a movable tube physically connected to the crosshead, preferably to the guide shoe of the crosshead.

According to a possible implementation of the first aspect, the telescopic tube is configured to extend and retract to follow the movement of the reciprocating crosshead.

According to a possible implementation of the first aspect, the valve is arranged upstream of the stationary pipe or in the inlet of the stationary pipe.

According to a possible implementation of the first aspect, the movable valve member is received in a cavity of the valve body, and wherein the shape of the movable valve member in cooperation with the shape of the cavity provides damping against movement of the movable valve member towards the first and/or second seats.

According to a possible implementation of the first aspect, the valve is an electronically controlled valve that opens and closes or restricts in response to a signal from a controller (electronic control unit).

According to a possible implementation of the first aspect, the controller is aware of the position of the movable tube and is configured to time the opening and closing or limiting of the electronic control valve in dependence of the position of the movable tube, preferably the controller is configured to close or limit the electronic control valve when the bellows is contracted (when the piston is moved from BDC to TDC) and to open the electronic control valve when the bellows is extended, or the controller is aware of the pressure in the bellows, and wherein the controller is configured to close or limit the electronic control valve when the pressure is above a threshold and to open the electronic control valve when the pressure is below a threshold, or wherein the controller is aware of the pressure in the bellows and is aware of the pressure supplied by the source, and wherein the controller is configured to close or limit the electronic control valve when the pressure in the bellows is equal to or higher than the pressure supplied by the Yu You source, and wherein the controller is configured to open the electronic control valve when the pressure in the bellows is lower than the pressure supplied by the source. The controller may learn the position of the movable tube directly (e.g., using a position sensor) or by knowing the angular position of the crankshaft (e.g., using an angular position sensor on the crankshaft).

According to a possible implementation of the first aspect, the valve is a check valve.

According to a possible implementation of the first aspect, the inlet port is arranged on a guide shoe of the crosshead, and wherein at least a portion of the tubing extends from the inlet port through the guide shoe and from the guide shoe to the piston rod, preferably via a crosshead pin.

According to a possible implementation of the first aspect, the movable tube is received in an at least partially sealed manner in the lumen of the stationary tube or the stationary tube is received in an at least partially sealed manner in the lumen of the movable tube.

According to a possible implementation of the first aspect, the movable tube is translatable relative to the stationary tube to follow the reciprocating motion of the crosshead.

According to a possible implementation of the first aspect, the piston is cooled by a flow of cooling and lubricating medium supplied to the piston via the bellows.

According to a possible implementation of the first aspect, the inner cavity of the telescopic tube is used for conveying cooling and lubrication medium from the connection point at the cylinder frame or at the intake manifold to the piston via the pipe in the crosshead and the piston rod.

The above and other objects are achieved by various aspects of the present disclosure. Further possible implementations will become apparent from the description and drawings, for example.

Drawings

In the following detailed portion of the disclosure, various aspects, embodiments, and implementations will be described in more detail with reference to exemplary embodiments shown in the drawings in which:

figure 1 is an elevation view of a large two-stroke internal combustion engine equipped with multiple turbochargers according to an exemplary embodiment,

figure 2 is a side elevation view of the large two-stroke internal combustion engine of figure 1,

figure 3 is a schematic view of a large two-stroke internal combustion engine according to figure 1,

fig. 4 is a cross-sectional view through the top of the engine frame, cylinder frame and cylinder liner of the engine of fig. 1, showing the cooling and lubrication medium supply to the crossheads and pistons,

fig. 5 is a cross-sectional view of an embodiment of a check valve in a cooling and lubrication medium supply, wherein the movable valve member is in a closed position,

fig. 6 is a cross-sectional view of the check valve of fig. 5, with the movable valve member in an open position,

figure 7 is a cross-sectional view of an interior portion of the housing of the check valve of figure 5,

figure 8 is a top view of the check valve of figure 5,

fig. 9 is a cross-sectional view of another embodiment of a check valve disposed in a cooling and lubrication oil supply, wherein the valve member is in an open position,

FIG. 10 is a cross-sectional view of the check valve of FIG. 9, with the movable valve member in a closed position, and

FIG. 11 is a schematic view of another embodiment in which the check valve is an electronically controlled one-way valve.

Detailed Description

Fig. 1, 2 and 3 show a large low-speed turbocharged two-stroke diesel engine 100 with a crankshaft 8 and a crosshead 9. FIG. 3 is a schematic illustration of a large low speed turbocharged two-stroke diesel engine and its intake and exhaust systems. In this example embodiment, the engine 100 has six cylinders (each cylinder is formed of the cylinder liner 1) in-line. Large low-speed turbocharged two-stroke diesel engines typically have four to fourteen cylinders 1 in-line, which cylinders 1 are carried by a cylinder frame 29, which cylinder frame 29 is carried by the engine frame 23. The engine 100 may be used, for example, as a main engine in a marine vessel, or as a stationary engine for operating a generator in a power plant. For example, the total output of engine 100 may be in the range of 1,000kw to 110,000 kw.

In this exemplary embodiment, the engine 100 is a two-stroke uniflow compression ignition engine 100 having a scavenging port 18 at the lower region of the cylinder liners 1 and a central exhaust valve 4 at the top of each cylinder liner 1. However, it will be appreciated that the engine 100 need not be compression-ignited (diesel principle), but may instead be a premixed engine (otto principle). Thus, in the present embodiment, the compression pressure of engine 100 will be high enough for compression ignition, but it will be appreciated that engine 100 may operate at a lower compression pressure and may be a premixed engine that is ignited by spark or similar means.

The scavenging air is introduced into the cylinder 1 through the intake system. The intake system comprises a scavenging gas receiver 2, which scavenging gas receiver 2 is connected to the cylinder 1 via a scavenging port 18.

The exhaust gas generated in the cylinder is discharged through an exhaust system comprising an exhaust gas receiver 3, which exhaust gas receiver 3 is connected to the cylinder 1 via an exhaust valve 4.

The intake system of the engine 100 comprises a scavenging air receiver 2 (in case Exhaust Gas Recirculation (EGR) is used, the scavenging air receiver will receive a mixture of exhaust gas and scavenging air). The scavenging air is transferred from the scavenging air receiver 2 to the scavenging ports 18 of the respective cylinders 1. The piston 10 reciprocating in the cylinder liner 1 between Bottom Dead Center (BDC) and Top Dead Center (TDC) compresses the scavenging air. Fuel is injected through a fuel valve 55 disposed in the cylinder head 28, followed by combustion and generation of exhaust gas. Alternatively, a fuel valve 55 is disposed in the cylinder liner and fuel is admitted during the piston's stroke from BDC to TDC, the mixture of scavenging air and fuel is compressed by the piston 10 and triggers ignition when the piston 10 is at or near TDC, followed by combustion and the production of exhaust gases.

The central discharge valve 4 is arranged in a central opening in the cylinder head 28. A plurality of, preferably three or four, fuel valves 55 are distributed in the cylinder head 28 around the central opening/discharge valve 4. The drain valve 4 is actuated by an electro-hydraulic drain valve actuation system (not shown) and controlled by a controller 50 (electronic control unit). The fuel valve 55 is supplied with fuel by a fuel supply system (not shown).

When the exhaust valve 4 is open, exhaust gas flows from the central opening in the cylinder head 28 through an exhaust system comprising an exhaust conduit associated with each cylinder 1 into the exhaust gas receiver 3 and on through the first exhaust line 19 to the turbine 8 of the turbocharger 5 (the engine 100 is provided with one or more turbochargers 5), from the turbine 8 through the second exhaust conduit to the outlet 21 via the electricity saver 20 and then into the atmosphere.

The turbine 8 of the turbocharger 5 drives a compressor 7 via the shaft of the turbocharger 5, which compressor 7 is supplied with fresh air via an air inlet 12. The compressor 7 delivers pressurized scavenging air to a scavenging air line 13 leading to the scavenging air receiver 2. The scavenging air in the scavenging air line 13 passes through an intercooler 14 for cooling the scavenging air and a mist trap 63 for removing water droplets.

The engine is provided with a lubrication system that provides pressurized lubrication medium to various components of the engine. The lubricating medium is also used to cool engine components, including the piston 10. Thus, the lubrication medium is a cooling and lubrication medium, and the lubrication system is formed with a source 40 having pressurized cooling and lubrication medium.

Turning now to fig. 4, source 40 is connected to fixed tube 31 of telescoping tube 32 via feed tube 41. The fixed tube 31 is physically connected to the cylinder frame 29. Preferably, the fixing tube 31 is fixed to the top plate 28 of the cylinder frame 29 at an upper end portion thereof, and the fixing tube 31 is fixed to the top plate 24 of the engine frame at a lower end portion thereof. The extension tube 32 includes a movable tube 32. In the illustrated embodiment, the movable tube 32 is received in an at least partially sealed manner within the interior cavity of the stationary tube 31, but it is understood that the stationary tube 31 may also be received in an at least partially sealed manner within the interior cavity of the movable tube 32. Thus, the movable tube 32 is movable in a translational manner with respect to the stationary tube 31 to follow the reciprocating movement of the crosshead, and the movable tube 32 moves in unison with the crosshead 9. In this embodiment, the movable tube 32 is fixed to the guide shoe 27 of the crosshead 9 at the lower end of the movable tube 32, the movable tube 32 being fluidly connected to an inlet port in the crosshead 9 at the guide shoe 27. The crankcase frame 23 is provided with a vertical guide plane 26 that receives a lateral force acting on the crosshead 9, and the guide shoe 27 is guided by the vertical guide plate 26. The crosshead 9 also comprises a crosshead pin 16, which crosshead pin 16 connects the guide shoe 27 to the larger end connected to the crankshaft 8.

The bellows 30 extends from a source of cooling and lubricating medium formed by a common rail 40, down into the cylinder frame 29 and into the crankcase frame 23 for attachment to the crosshead 9 by the lower end of the bellows 30. The telescopic tube 30 comprises a stationary tube 31 connected to the common rail 40 and a concentrically arranged movable tube 32 connected to the crosshead 9. The bellows 30 delivers cooling and lubricating medium to a conduit 36 in the cross-head 9, which conduit 36 extends through the piston rod 15 into the piston 10 and back to the piston rod 15 for cooling the cooled piston 10. In this embodiment of engine 100, one extension tube 30 is provided for each cylinder, but it will be appreciated that more than one extension tube 30 may be provided for each cylinder for redundancy reasons.

In this embodiment, the line 36 starts at an inlet port, which in this embodiment is arranged in the upper side of the guide shoe 27, passes through the guide shoe 27 and then through the cross pin 16 into the piston rod 15.

A check valve 33 is fluidly arranged between the bellows 30 and the source 40. In the present embodiment, the check valve 33 is disposed at the upper end of the stationary pipe 31, i.e., at the inlet of the stationary pipe 31. However, it should be noted that the check valve 33 may be arranged in the crosshead 9 or may be arranged anywhere between the crosshead 9 and the source 40. The check valve 30 may be supported by the top plate 28 of the cylinder frame 29 or the intake manifold. The check valve 30 is configured to allow flow from the source 40 to the bellows 30 and to prevent flow from the bellows 30 to the source 40. By preventing backflow, a substantial increase in the flow of cooling and lubricating medium to the piston 10 can be ensured, thereby improving cooling of the piston 10. In particular, the flow of cooling medium to the piston occurs during a greater part of the rotation of the crankshaft 8, i.e. in prior art engines, no or little cooling medium flows to the piston 10 during most of the rotation of the crankshaft, and by preventing back flow, the cooling medium flows to the piston 10 substantially throughout the rotation of the crankshaft 8, thereby increasing the average flow rate of cooling medium to the piston 10 and improving the cooling of the piston 10.

Fig. 5 to 8 are various views of an embodiment of the check valve 33. Fig. 5 and 6 are cross-sectional views of an embodiment of the check valve 33, showing the valve member 35 in a closed position and an open position, respectively. In this embodiment, the check valve 33 comprises a movable valve member 35 in the form of a ball (sphere), which movable valve member 35 is received in a cavity in the housing of the check valve 33. In the present embodiment, the housing of the check valve 33 is formed of an outer housing portion 39 and an inner housing portion 37, the inner housing portion 37 being inserted into the outer housing portion 39. As shown, the valve housing is mounted on the top plate 28 of the cylinder frame 23, but it is understood that the check valve 33 may be secured to the engine 100 in other ways. In this embodiment, the upper end of the fixed tube 31 is fixed to the opposite side of the top plate 28 and the feed tube 41 is directly connected to the check valve 33, but it will be appreciated that the check valve 33 may be connected to the source 40 of cooling and lubricating liquid and the bellows 30 in other ways.

The cavity in the body of the check valve 33 allows the movable valve member 35 to move between a closed position shown in fig. 5, in which the valve member rests on the first seat, and an open position shown in fig. 6, in which the valve member 35 rests on the second seat. Thus, when installed in an engine or in use, gravity may affect the valve member 35 and urge the valve member 35 toward the second seat. In this embodiment, the first and second seats are arranged at opposite ends of the cavity, wherein the first seat is an upper seat with respect to the gravitational field of the earth and the second seat is a lower seat with respect to the gravitational field of the earth. The first seat is associated with an inlet port of the check valve and the second seat is associated with an outlet port of the check valve. The cavity further comprises one or more side channels 36, which side channels 36 establish a fluid connection around the movable valve member 35 to allow cooling and lubricating liquid to pass around the movable valve member 35 to flow from the inlet port to the outlet port. The first seat is shaped to form an airtight seal with the movable valve member 35 when the movable valve member is resting on the first seat to prevent the flow of cooling and lubrication medium in a direction from the outlet to the inlet. The second seat is shaped to establish one or more openings between the second seat and the movable valve member 35 when the movable valve member 35 is resting on the second seat to enable the cooling and lubrication medium to pass between the movable valve member 35 and the second seat, as shown in fig. 6. These openings are in this embodiment established by a plurality of axially directed and circumferentially distributed bores in the inner housing part 37 which meet a second seat which is also formed by the inner housing part and is substantially conical.

In this embodiment, there is no biasing means to urge the movable valve member towards the open or closed position other than the gravitational field of the earth urging the movable valve member 35 towards the open seat/position. During operation of engine 100, the position of movable valve member 35 is determined by the pressure differential across check valve 33, which creates a force on movable valve member 35 that is many times greater than the force caused by the action of gravity on movable valve member 35, which will have only a small effect on the movement of the movable valve member during engine operation. When the pressure at the inlet of the check valve 33, i.e. the pressure in the feed line 41, is higher than the pressure at the outlet of the check valve 33, i.e. the pressure in the stationary pipe 31, the movable valve member 35 is pushed by the pressure difference acting on the movable valve member 35 towards the open seat as shown in fig. 6 and enables the cooling and lubrication medium to flow from the inlet of the check valve 33 to the outlet of the check valve 33. When the pressure at the inlet of the check valve 33 is lower than the pressure at the outlet of the check valve, the movable valve member 35 is pushed towards the closed seat by the pressure difference acting on the movable valve member 35 and prevents the flow of cooling and lubrication medium from the outlet of the check valve 33 towards the inlet of the check valve 33.

Fig. 9 and 10 illustrate another embodiment of the check valve 33. In this embodiment, the same or similar structures and features as those previously described or illustrated herein are denoted by the same reference numerals as previously used for simplicity. In this embodiment, the movable valve member 35 is a cylindrical body having a stepwise change in diameter, and the cavity is shaped accordingly. In fig. 9, the check valve 33 is shown with the movable valve member 35 in an open position, and in fig. 10, the check valve 33 is shown with the movable valve member 35 in a closed position, wherein the gravitational field of the earth pushes the movable valve member to the open position shown in fig. 9.

The stepped change in diameter causes interaction between the moveable valve member 35 and the cavity to form a damper for movement of the moveable valve member 35 towards the first seat and towards the second seat, thereby ensuring a soft landing of the moveable valve member 35 on the respective seats. The first damping chamber 38 captures the cooling and lubrication medium as the movable valve member 35 moves toward the first seat, and the captured cooling and lubrication medium needs to be forced out of the first damping chamber 38 through the gap between the movable valve member 35 and the surface of the valve housing forming the cavity. The second damping chamber 39 captures the cooling and lubrication medium as the movable valve member 35 moves towards the second seat and the captured cooling and lubrication medium needs to be forced out of the second damping chamber 39 through the gap between the movable valve member 35 and the surface of the valve housing forming the cavity. In this embodiment, the ends of the side channels 36 form the outlet ports of the check valve 33. The operation of the check valve 33 according to this embodiment is the same as that in the embodiment of fig. 5 to 8 except for the damping function. The damping function reduces mechanical stress on the elements of the check valve 33, further improving reliability.

In the variant of the embodiment above and below, the closed position is not completely closed, but almost completely closed, so that a restriction is placed on the flow of cooling and lubricating medium.

Fig. 11 shows another embodiment of the check valve 33. In this embodiment, for simplicity, the same or similar structures and features as those previously described or illustrated herein are denoted by the same reference numerals as previously used. In this embodiment, the check valve 33 is an electronically controlled 2/2 valve. In this embodiment, the electronically controlled 2/2 valve is mechanically biased to an open position and is movable to a closed or restricting position by an electric actuator, but it will be appreciated that other types of electronically controlled 2/2 valves are equally suitable as the check valve 33. The electronically controlled check valve 33 is controlled by a signal from a controller 50 (electronic control unit). In an embodiment, the controller 50 is aware of the position of the movable tube 32 and is configured to time the opening and closing/limiting of the electronically controlled valve 33 depending on the position of the movable tube 32, i.e. the controller 50 is configured to close or limit the electronically controlled check valve 33 when the bellows 30 is contracted and the controller 50 is configured to open the electronically controlled check valve 33 when the bellows 30 is extended. In an embodiment, the position of the movable tube 32 is determined by a position sensor (not shown) associated with the movable tube 32 and communicated to the controller 50. Alternatively, the position of the movable tube is indirectly determined from the rotational position of the crankshaft 8 by the position sensor 77, and the controller 50 knows the signal from the position sensor 77. In another embodiment, the controller 50 knows the pressure in the bellows 30, for example by a pressure sensor, and the controller 50 is configured to close or restrict the electronically controlled check valve 33 when the pressure is above a threshold and to open the electronically controlled check valve 33 when the pressure is below a threshold. In another embodiment, the controller 50 knows the pressure in the bellows 30, for example by a pressure sensor, and the controller 50 knows the pressure supplied by the source 40, for example by another pressure sensor measuring the pressure in the feed line 41, and the controller 50 is configured to close or restrict the electronically controlled check valve 33 when the pressure in the bellows is equal to or higher than the pressure supplied by the Yu You source, and wherein the controller 50 is configured to open the electronically controlled check valve 33 when the pressure in the bellows is lower than the pressure in the feed line 41. Thus, in operation, back flow of cooling lubricating liquid from the bellows 30 toward the source 40 is prevented or reduced.

For all embodiments, bellows 30 acts as a positive displacement pump when contracted and, at the same time, prevents or limits backflow from bellows 30 toward the source. Thus, a more stable flow of cooling and lubricating medium to the piston 10 is ensured, and thus an improved cooling of the piston 10 is ensured.

The engine has been described in connection with various embodiments herein. However, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed subject matter, from a study of the drawings, the disclosure, and the appended claims. In the claims, the term "comprising" does not exclude other elements or steps and the indefinite article "a" or "an" does not exclude a plurality. A single controller or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

The reference signs used in the claims shall not be construed as limiting the scope. The drawings are intended to be read (e.g., cross-hatching, arrangement of parts, proportion, degree, etc.) together with the specification, unless otherwise indicated, and are to be considered a portion of the entire written description of this disclosure.

Claims

1. A large turbocharged two-stroke uniflow internal combustion engine (100) of the crosshead type, the engine (100) comprising:

at least one cylinder liner (1), the at least one cylinder liner (1) having a scavenge port (18) at a lower end of the at least one cylinder liner (1) and a drain valve (4) at an upper end of the at least one cylinder liner (1),

a reciprocating piston (10) located in the at least one cylinder liner (1), the reciprocating piston (10) being connected to a reciprocating crosshead (9) by a piston rod (15),

a source (40) of pressurized cooling and lubricating medium,

a bellows (30), said bellows (30) fluidly connecting said source to an inlet port on said crosshead (9),

-a conduit (36), which conduit (36) extends from the inlet port to the piston (10), preferably the conduit (36) extends through the cross head (9) and through the piston rod (15), and

a valve (33), the valve (33) being configured to: allowing a flow of cooling and lubricating medium from the source (40) to the telescopic tube (30) and preventing or at least limiting the flow of cooling and lubricating medium from the telescopic tube (30) to the source (40), characterized in that the valve (33) comprises a movable valve member (35), the movable valve member (35) being arranged movable between a closed or limiting position on the first seat and an open position on the second seat,

wherein the movable valve member (35) is biased to the open position by gravity only.

2. The engine (100) according to claim 1, wherein the at least one cylinder liner (1) is supported by a cylinder frame (29), the telescopic tube (30) comprising a stationary tube (31) and a movable tube (32), the stationary tube (31) being physically connected to the cylinder frame (29), the movable tube (32) being physically connected to the crosshead (9), preferably the movable tube (32) being physically connected to a guide shoe (29) of the crosshead (9).

3. The engine (100) according to claim 2, wherein the valve (33) is arranged upstream of the stationary pipe (31) or the valve (33) is arranged in an inlet of the stationary pipe (31).

4. An engine (100) according to any one of claims 1 to 3, wherein the movable valve member (35) is received in a cavity of a body (37, 39) of the valve (33), and wherein the shape of the movable valve member (35) in cooperation with the shape of the cavity provides damping of movement of the movable valve member (35) towards the first and/or second seats.

5. The engine (100) according to any one of claims 1 to 4,

wherein the valve (33) is a check valve.

6. The engine (100) according to any one of claims 1 to 5,

wherein the valve (33) is an electronically controlled valve that opens and closes or restricts in response to a signal from a controller (50).

7. The engine (100) of claim 6, wherein the controller (50) knows the position of the movable tube (32) and the controller (50) is configured to time the opening and closing or limiting of the electronic control valve depending on the position of the movable tube (32), preferably the controller (50) is configured to close or limit the electronic control valve when the telescopic tube (30) is contracted and the controller (50) is configured to open the electronic control valve when the telescopic tube is extended.

8. The engine (100) of claim 7, wherein the controller (50) is aware of the pressure in the bellows (30), and wherein the controller (50) is configured to close or restrict the electronically controlled valve when the pressure is above a threshold,

or wherein the controller (50) knows the pressure in the bellows (30) and knows the pressure supplied by the source (40), and wherein the controller (50) is configured to close or restrict the electronic control valve when the pressure in the bellows (30) is equal to or higher than the pressure supplied by the source (40) or a target pressure, and wherein the controller is configured to open the electronic control valve when the pressure in the bellows (30) is lower than the pressure supplied by the source (40) or the target pressure.