JP7611299B2 - Large turbocharged two-stroke internal combustion engine having improved piston cooling means - Google Patents

Description

The subject matter disclosed in this application relates to a large turbocharged two-stroke internal combustion engine having a crosshead, with at least one cylinder receiving a reciprocating piston, the reciprocating piston being cooled by a flow of cooling medium supplied through a telescopic tube connecting the cylinder frame to the crosshead.

background

Large turbocharged two-stroke internal combustion engines are often used in the propulsion systems of large ships and as prime movers in power plants. Their size, weight and power output set them apart from other combustion engines and place them in a unique category. These engines are constructed with a crosshead to eliminate side pressure on the pistons, as increased height is less of a problem. Such engines are usually run on natural gas, petroleum gas, methanol, ethane or fuel oil.

Large turbocharged two-stroke internal combustion engines may be operated as compression ignition, i.e. on the Diesel principle, or as premixed engines, i.e. on the Otto principle, in which scavenging gases are mixed with fuel during the piston stroke from bottom dead centre (BDC) to top dead centre (TDC).

The pistons are usually made of heat-resistant steel to withstand the high temperatures in the combustion chamber. They are also cooled by a cooling medium, such as lubricating oil, to prevent them from overheating while the engine is running.

The engine lubrication system supplies the various components of the engine with a lubricating medium. The lubricating medium is also used to cool the pistons. Typically, the medium used is lubricating oil.

One branch of the lubrication system is connected to the crosshead by a telescopic tube. From there, the lubricating and cooling medium travels up the piston rod to cool the pistons and then down to perform several functions, such as lubricating the crosshead bearings and lubricating the guide shoes that guide the crosshead between the vertical guide plates. One part of the telescopic tube is connected to the crosshead and another part of the telescopic tube traverses the cylinder frame and is connected to the cylinder frame or to the inlet manifold. The bore of the telescopic tube is then used to transport the cooling medium from the connection point of the cylinder frame through the crosshead and the conduits in the piston rod to the pistons. The telescopic tube has an outer tube and an inner tube that is at least partially received in the bore of the outer tube. The inner tube can translate to follow the reciprocating movement of the crosshead relative to the cylinder frame.

Japanese Utility Model Publication No. 57-176616 discloses a large crosshead type turbocharged two-stroke uniflow internal combustion engine with a telescopic pipe that fluidly connects a supply source of cooling/lubricating liquid to an inlet port of the crosshead, and a valve that allows the flow of cooling/lubricating liquid from the supply source to the telescopic pipe but prevents the flow of cooling/lubricating liquid from the telescopic pipe toward the cooling/lubricating liquid supply source. The valve has a spring that biases the valve member toward the valve seat.

Abstract

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

Testing and simulations performed by the inventors of the present application have determined that cooling of the piston varies significantly during the engine cycle, with the majority of the cooling occurring during a relatively small portion of the engine cycle. Through further testing and simulations, the inventors have arrived at the insight that this variation is caused by variations in the pressure and flow rate of the cooling medium to the piston. Further analysis and insight have determined that these pressure and flow rate variations are caused by the expansion and contraction of the telescopic tube during the engine cycle.

According to a first aspect, there is provided a crosshead type large turbocharged two-stroke uniflow internal combustion engine as follows. This engine comprises:
at least one cylinder liner having a scavenge port at a lower end and an exhaust valve at an upper end;
a reciprocating piston within the at least one cylinder liner, the reciprocating piston being connected to a reciprocating crosshead by a piston rod;
A source of pressurized cooling and lubricating medium;
a telescopic tube fluidly connecting the source to an inlet port of the crosshead;
a conduit extending from the inlet port to the piston, preferably through the crosshead and the piston rod;
a valve configured to permit flow of the cooling and lubricating medium from the source to the telescopic tube and to prevent or restrict flow of the cooling and lubricating medium from the telescopic tube to the source;
Equipped with
the valve has a movable valve member configured to be movable between a closed or restricted position on a first valve seat and an open position on a second valve seat;
The movable valve member is biased toward the open position by gravity alone.

By providing a check valve or a valve acting like a check valve upstream of the telescopic tube or at the inlet of the telescopic tube, the backflow of the cooling medium during the compression stroke of the piston (stroke from BDC to TDC), i.e. when the telescopic tube contracts, can be avoided or at least reduced, thereby making the flow of the cooling medium to the piston more constant throughout the engine cycle. The inventors have arrived at the insight that if the return flow from the telescopic tube to the source is prevented or restricted, the flow rate of the cooling medium increases when the telescopic tube contracts (i.e. during the compression stroke of the piston) because the telescopic tube acts as a positive displacement pump. As a result, the flow of the cooling medium is substantially increased throughout the engine cycle, and the cooling capacity is increased and the piston cooling is improved by extending the time for active cooling. The valve has a movable valve member arranged to be movable between a closed or restricted position on a first valve seat and an open position on a second valve seat, the movable valve member being biased towards the open position by gravity alone.

Improved piston cooling can reduce piston temperatures and can reduce costs by using less heat-resistant steels for the piston. Improved piston cooling can also help increase piston combustion margins. Furthermore, it can help increase the layout freedom of the fuel valve atomizer (especially the freedom of piston direction).

By using a valve having a first valve seat associated with the closed position of the valve member and a second valve seat associated with the open position of the valve member, with the valve member biased toward the second valve seat or open position solely by gravity, a significantly more reliable valve is provided compared to the failure-prone prior art spring biased valve members.

In one embodiment of the first aspect, the at least one cylinder liner is supported by a cylinder frame, and the telescopic tube includes a fixed tube physically coupled to the cylinder frame and a movable tube physically coupled to the crosshead. The movable tube is preferably physically coupled to a guide shoe of the crosshead.

In one example of an implementation form of the first aspect, the telescopic tube is configured to extend and retract in response to the movement of the reciprocating crosshead.

In one example of the implementation of the first aspect, the valve is disposed upstream of the fixed pipe or at the inlet of the fixed pipe.

In one implementation of the first aspect, the movable valve member is received in a cavity in the valve body, and the shape of the movable valve member in combination with the shape of the cavity provides damping for movement of the movable valve member to the first valve seat and/or the second valve seat.

In one example of an implementation of the first aspect, the valve is an electronically controlled valve that opens, closes, or restricts in response to a signal from a controller (electronic control device).

In one implementation of the first aspect, the controller is informed of the position of the movable tube and is configured to adjust the timing of opening, closing or restricting the electronically controlled valve as a function of the position of the movable tube. The controller is preferably configured to close or restrict the electronically controlled valve when the telescopic tube retracts (when the piston moves from BDC to TDC) and to open the electronically controlled valve when the telescopic tube extends.

Alternatively, the controller is informed of the pressure in the telescopic tube and is configured to close or limit the electronically controlled valve when the pressure is equal to or greater than a threshold value and to open the electronically controlled valve when the pressure is less than the threshold value.

Alternatively, the controller is informed of the pressure in the telescopic tube and the pressure supplied from the source, and is configured to close or limit the electronically controlled valve when the pressure in the telescopic tube is equal to or higher than the pressure supplied from the source, and to open the electronically controlled valve when the pressure in the telescopic tube is lower than the pressure supplied from the source.

The controller may know the position of the movable tube directly (e.g., using a position sensor), or the controller may know the position of the movable tube by knowing the angular position of the crankshaft (e.g., using an angular position sensor for the crankshaft).

In one embodiment of the first aspect, the valve is a check valve.

In one embodiment of the first aspect, the inlet port is disposed on a guide shoe of the crosshead, and at least a portion of the conduit extends from the inlet port through the guide shoe and from the guide shoe to the piston rod, preferably through a crosshead pin.

In one embodiment of the first aspect, the movable tube is at least partially sealed to the inner lumen of the fixed tube, or the fixed tube is at least partially sealed to the inner lumen of the movable tube.

In one example of the implementation of the first aspect, the movable tube is capable of translational movement relative to the fixed tube in response to the reciprocating motion of the crosshead.

In one embodiment of the first aspect, the piston is cooled by a flow of a cooling and lubricating medium that is supplied to the piston through an expandable tube.

In one implementation of the first aspect, the bore of the telescopic tube is used to transport the cooling/lubricating medium from the connection of the cylinder frame or the inlet manifold, through the crosshead, and through a conduit in the piston rod to the piston.

This and other objects are achieved by the features of the present disclosure. Various possible implementations will become apparent from the specification and drawings.

Various aspects, embodiments, and implementations will be described in detail below with reference to exemplary embodiments illustrated in the drawings.
FIG. 1 is a front overhead view of a large two-stroke internal combustion engine with multiple turbochargers according to an exemplary embodiment. FIG. 2 is a rear view of the large two-stroke internal combustion engine of FIG. 1 . 2 is a schematic representation of the large two-stroke internal combustion engine of FIG. FIG. 2 is a cross-sectional view through the engine frame, cylinder frame and upper part of the cylinder liner of the engine of FIG. 1, showing the supply of cooling and lubricating media to the crosshead and pistons. 1 is a cross-sectional view of an embodiment of a check valve in a cooling and lubricating medium supply with a movable valve member in a closed position; 6 is a cross-sectional view of the check valve of FIG. 5 when the movable valve member is in an open position. FIG. 6 is a cross-sectional view showing the inside of the housing of the check valve of FIG. 5 . FIG. 6 is a top view of the check valve of FIG. 13 is a cross-sectional view of another embodiment of a check valve located in a cooling and lubricating oil supply, the valve member shown 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. 1 is a schematic representation of another embodiment in which the check valve is an electronically controlled one-way valve.

Detailed explanation

Figures 1 to 3 depict a turbocharged large slow-speed two-stroke diesel engine 100. The engine has a crankshaft 8 and a crosshead 9. Figure 3 is a schematic representation of a turbocharged large slow-speed two-stroke diesel engine with its intake and exhaust systems. In this embodiment 100, the engine has six cylinders in series. Each cylinder is formed by a cylinder liner 1. A turbocharged large slow-speed two-stroke diesel engine typically has 4 to 14 cylinders arranged in series. The cylinders are supported on a cylinder frame 29. The cylinder frame 23 is supported on an engine frame 23. The engine 100 can be used, for example, as a main engine for a ship or as a stationary engine for driving a generator in a power plant. The total power output of the engine 100 can be, for example, 1000 kW to 110000 kW.

The engine 100 in this embodiment is a two-stroke uniflow compression ignition engine, with each cylinder liner 1 having a scavenging port 18 in its lower region and an exhaust valve at the top center. However, the engine 100 does not necessarily have to be compression ignition (Diesel principle) and may be a premixed engine (Otto principle) in some embodiments. In the embodiment presented here, the compression pressure of the engine 100 is high enough to provide compression ignition. However, the engine 100 may be a premixed engine operating at a lower compression pressure and ignited by a spark or similar means.

The scavenging air is introduced into the cylinder 1 through the intake system. The intake system includes a scavenging receiver 2 that is connected to the cylinder 1 via a scavenging port 18.

The exhaust gas generated in the cylinder is exhausted through the exhaust system. The exhaust system includes an exhaust receiver 3 connected to the cylinder 1 via an exhaust valve 4.

The intake system of the engine 1 includes a scavenging receiver 2. When exhaust gas recirculation (EGR) is used, the scavenging receiver receives a mixture of scavenging air and exhaust gas. The scavenging air is directed through the scavenging receiver 2 to the scavenging ports 18 of each cylinder 1. The piston 10 reciprocates between bottom dead center (BDC) and top dead center (TDC) in the cylinder liner 1, compressing the scavenging air. Fuel is injected through a fuel valve 55 located in the cylinder cover 28. Combustion ensues and exhaust gases are produced. Alternatively, the fuel valve 55 is located in the cylinder liner and fuel is introduced during the piston stroke from BDC to TDC. The scavenging air and fuel mixture is compressed by the piston 10, and ignition is induced when the piston 10 is at or near TDC, combustion ensues and exhaust gases are produced.

A central exhaust valve 4 is disposed in the central opening of the cylinder cover 28. A plurality of (preferably three or four) fuel valves 55 are also disposed in the cylinder cover 28 around the central opening or the central exhaust valve 4. The exhaust valves 4 are actuated by an electrohydraulic exhaust valve actuation system (not shown) and controlled by a controller (electronic control unit) 50. The fuel valves 55 are supplied with fuel by a fuel supply system (not shown).

When the exhaust valve 4 is opened, the exhaust gases pass through a central opening in the cylinder cover 28, through an exhaust system having exhaust ducts (provided for each cylinder 1), into the exhaust receiver 3, and through a first exhaust line 19 to the turbine 8 of the turbocharger 5. From there, the exhaust gases pass through a second exhaust line, via an economizer 20, to an outlet 21, and are discharged into the atmosphere. The engine 100 is equipped with one or more turbochargers 5.

The turbine 8 of the turbocharger 5 drives the compressor 7 via the turbocharger 5 shaft. The compressor 7 is supplied with outside air through an air intake 12. The compressor 7 sends compressed scavenging air to a scavenging pipe 13 that is connected to the scavenging receiver 2. The scavenging air in the scavenging pipe 13 passes through an intercooler 14 and a water mist catcher 63 to cool the scavenging air and remove water droplets.

The engine includes a lubrication system that supplies pressurized lubricating medium to various components of the engine. The lubricating medium is also used to cool engine components including the piston 10. The lubricating medium is therefore a cooling and lubricating medium (also referred to herein as cooling-lubricating medium), and the lubrication system forms a source 40 of pressurized cooling-lubricating medium.

4, the supply source 40 is connected to the fixed tube 31 of the telescopic tube 32 via a supply tube 41. The fixed tube 31 is physically connected to the cylinder frame 29, preferably with the upper end of the fixed tube 31 fixed to the top plate 28 of the cylinder frame 29 and the lower end fixed to the top plate 24 of the engine frame. The telescopic tube 32 includes a movable tube 32. In the illustrated embodiment, the movable tube 32 is at least partially sealed in the lumen of the fixed tube 31. (However, in some embodiments, the fixed tube 31 may be at least partially sealed in the lumen of the movable tube 32 as well.) The movable tube 32 can then translate relative to the fixed tube 31 in response to the reciprocating motion of the crosshead 9, and the movable tube 32 moves together with the crosshead 9. In this embodiment, the movable tube 32 is fixed at its lower end to the guide shoe 27 of the crosshead 9, where it is fluidly connected to the inlet port of the crosshead 9. The crankcase frame 23 is provided with a vertical guide surface 26 that receives the lateral force acting on the crosshead 9, and the guide shoe 27 is guided by the vertical guide plate 26. The crosshead 9 further includes a crosshead pin 16. The crosshead pin 16 connects the guide shoe 27 to the large end that is connected to the crankshaft 8.

The telescopic tube 30 originates from a cooling and lubricating medium source (which may be formed by a common rail 40), descends through the cylinder frame 29, and passes into the crankcase frame 23, with its lower end attached to the crosshead 9. The telescopic tube 30 consists of a fixed tube 31 connected to the common rail 40 and a movable tube 32 connected to the crosshead 9. The movable tube 32 is arranged concentrically with the fixed tube 31. A conduit 36 is provided in the crosshead 9. The conduit 36 passes through the piston rod 15 into the piston 10 and back to the piston rod 15. The telescopic tube 30 delivers the cooling and lubricating medium to the conduit 36 to cool the piston 10. In this embodiment of the engine 100, each cylinder is provided with one telescopic tube 30, but for redundancy reasons, there may be more than one telescopic tube 30 for each cylinder.

In this embodiment, the conduit 36 begins at an inlet port located on the upper side of the guide shoe 27, passes through the guide shoe 27, and enters the piston rod 15 through the crosshead pin 16.

A check valve 33 is provided in the flow path between the telescopic tube 30 and the source 40. In this embodiment, the check valve 33 is located at the upper end of the fixed tube 31, i.e., at the inlet of the fixed tube 31. However, it should be noted that the check valve 33 can be located anywhere in the crosshead 9 or between the crosshead 9 and the source 40. The check valve 30 can be supported by the top plate 28 of the cylinder frame 29 or by the intake manifold. The check valve 30 is configured to allow flow from the source 40 to the telescopic tube 30 and to block flow from the telescopic tube 30 to the source 40. Blocking the return flow ensures that the flow of cooling and lubricating medium to the piston 10 is substantially increased, thereby improving the cooling of the piston 10. In particular, the flow of cooling medium to the piston occurs during a much larger portion of the rotation of the crankshaft 8 compared to the prior art. That is, in the prior art engine, there is no or almost no flow of cooling medium to the piston 10 for a significant period during the rotation of the crankshaft. By blocking the return flow, the cooling medium flows past the piston 10 for almost the entire rotation of the crankshaft 8, thereby increasing the average flow rate of the cooling medium to the piston 10 and improving cooling of the piston 10.

5-8 are various schematic diagrams showing an embodiment of the check valve 33. FIGS. 5 and 6 are cross-sectional views of an embodiment of the check valve 33, showing the valve member 35 in the closed and open positions, respectively. In this embodiment, the check valve 33 has a movable valve member 35 in the form of a ball received in a cavity in the housing of the check valve 33. In this embodiment, the housing of the check valve 33 is formed by an outer housing portion 39 and an inner housing portion 37 inserted into the outer housing portion 39. As shown, the valve housing is attached to the top plate 28 of the cylinder frame 23, but 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 secured to the opposite side of the top plate 28, and the supply tube 41 is directly connected to the check valve 33, but it should be understood that the check valve 33 may be connected to the cooling/lubricating liquid source 40 and the telescopic tube 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 where the valve member 35 sits on a first valve seat, and an open position shown in FIG. 6 where the valve member 35 sits on a second valve seat. Thus, when installed in the engine or in use, gravity acts on the valve member 35 to bias it toward the second valve seat. In this embodiment, the first and second valve seats are located at opposite ends of the cavity, with the first valve seat being an upper valve seat with respect to the Earth's gravitational field, and the second valve seat being a lower valve seat with respect to the Earth's gravitational field. The first valve seat is associated with the inlet port of the check valve, and the second valve seat is associated with the outlet port of the check valve. The cavity also has one or more side passages 36 that establish a fluid connection around the movable valve member 35. The side passages 36 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 valve seat is configured to form an airtight seal with the movable valve member 35 when the movable valve member 35 is seated on the first valve seat to prevent the flow of the cooling/lubricating medium in the direction from the outlet to the inlet. The second valve seat has a shape such that one or more gaps are formed between the second valve seat and the movable valve member 35 so that the cooling/lubricating medium can pass between the movable valve member 35 and the second valve seat when the movable valve member 35 is seated on the second valve seat, as shown in FIG. 6. In this embodiment, these gaps are formed by a number of axially oriented and circumferentially distributed bores provided in the inner housing part 37 and a substantially conical second valve seat that meets the bores and is also formed by the inner housing part.

In this embodiment, there is no means for biasing the movable valve member 35 to the open or closed position other than the gravitational field of the earth pulling the movable valve member 35 toward the second valve seat/open position. During operation of the engine 100, the position of the movable valve member 35 is determined by the pressure difference applied to the inlet and outlet sides of the check valve 33. Therefore, the force acting on the movable valve member 35 is many times greater than the force acting on the movable valve member 35 due to the effect of gravity, and gravity has only a small effect on the movement of the movable valve member 35 during engine operation. When the pressure at the inlet of the check valve 33, i.e., the pressure in the supply pipe 41, is higher than the pressure at the outlet of the check valve 33 (i.e., the pressure in the fixed pipe 31), the movable valve member 35 is urged to move in the opening direction by the pressure difference acting on the movable valve member 35, as shown in FIG. 6, and the cooling/lubricating medium is allowed to flow from the inlet of the check valve 33 to the outlet of the check valve 33. In addition, when the pressure at the inlet of the check valve 33 is lower than the pressure at the outlet of the check valve, the pressure difference acting on the movable valve member 35 causes the movable valve member 35 to move to the closing side, preventing the cooling/lubricating medium from flowing from the outlet of the check valve 33 to the inlet of the check valve 33.

Figures 9 and 10 show another embodiment of the check valve 33. In this embodiment, features and functions similar to those already described or illustrated are numbered as previously used. In this embodiment, the movable valve member 35 is a cylinder with a stepped diameter and the cavity is shaped accordingly. The check valve 33 is depicted with the movable valve member 35 in an open position in Figure 9 and with the movable valve member 35 in a closed position in Figure 10. The gravitational field biases the movable valve member 35 to the open position of Figure 9.

The stepwise change in diameter creates an interaction between the movable valve member 35 and the cavity, forming a damping means for the movement of the movable valve member 35 to the first valve seat and the second valve seat. This allows the movable valve member 35 to be seated gently on each valve seat. The first damping chamber 38 captures the cooling/lubricating medium as the movable valve member 35 moves toward the first valve seat and squeezes the captured cooling/lubricating medium out of the first damping chamber 38 through the clearance between the movable valve member 35 and the valve housing surface (the surface forming the cavity). The second damping chamber 39 captures the cooling/lubricating medium as the movable valve member 35 moves toward the second valve seat and squeezes the captured cooling/lubricating medium out of the second damping chamber 39 through the clearance between the movable valve member 35 and the valve housing surface (the surface forming the cavity). In this embodiment, the tip of the side passage 36 forms the outlet port of the check valve 33. Other than the damping function, the operation of the check valve 33 in this embodiment is the same as that in the embodiment of Figures 5 to 8. This damping function reduces mechanical stress on the elements of the check valve 33, further improving its reliability.

In the above and following embodiment variations, the closed position is not completely closed, but is mostly closed, which restricts the flow of the cooling and lubricating medium.

11 shows another embodiment of the check valve 33. In this embodiment, features and functions similar to those already described or illustrated are given 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 is mechanically biased to an open position and can be moved to a closed or restricted position by an electric actuator. It should be understood 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 some embodiments, the controller 50 is informed of the position of the movable tube 32 and is configured to adjust the timing of opening, closing, or restricting the electronically controlled valve 33 as a function of the position of the movable tube 32. That is, the controller 50 is configured to close or restrict the electronically controlled valve 33 when the telescopic tube 30 retracts and to open the electronically controlled valve 33 when the telescopic tube 30 extends. In some embodiments, the position of the movable tube 32 is determined by a position sensor (not shown) associated with the movable tube 32 and transmitted to the controller 50. Alternatively, the position of the movable tube is indirectly determined from the rotational position of the crankshaft 8 via a position sensor 77, which transmits a signal to the controller 50. In another embodiment, the controller 50 is informed of the pressure in the telescopic tube, e.g., from a pressure sensor, and the controller 50 is configured to close or limit the electronically controlled valve 33 when the pressure is equal to or greater than a threshold value, and to open the electronically controlled check valve 33 when the pressure is less than the threshold value. In another embodiment, the controller 50 is informed of the pressure in the telescopic tube, e.g., from a pressure sensor, and is informed of the pressure provided by the source 40, e.g., from another pressure sensor measuring the pressure in the supply tube 41. The controller 50 is then configured to close or limit the electronically controlled valve 33 when the pressure in the telescopic tube is equal to or greater than the pressure provided by the source, and to open the electronically controlled check valve 33 when the pressure in the telescopic tube is less than the pressure in the supply tube 41. Thus, during operation, return flow of cooling/lubricating liquid from the expansion tube 30 to the source 40 is prevented or reduced.

In all embodiments, the telescopic tube 30 functions as a positive displacement pump when contracted while simultaneously preventing or restricting return flow from the telescopic tube 30 to the source. This reduces fluctuations in the flow of cooling/lubricating medium to the piston 10, thereby improving the cooling capacity of the piston 10.

The engine has been described using various embodiments. However, upon review of the specification, drawings, and claims of this application, those skilled in the art will understand and be able to embody many variations in addition to the described embodiments in implementing the claimed invention. The words "comprise", "have", and "include" in the claims do not exclude the presence of elements or steps not recited. The absence of a claim expressly stating a plurality of elements does not exclude the presence of a plurality of the elements. The functions of several elements recited in the claims may be performed by a single controller or other unit. The fact that several items are recited in separate dependent claims does not exclude them from being implemented in combination, and may be implemented to advantage in combination.

Any reference signs used in the claims should not be construed as limiting the scope of the invention. Unless otherwise noted, the drawings are intended to be read together with the specification and are an integral part of this disclosure.

Claims (7)

A large crosshead type turbocharged two-stroke uniflow internal combustion engine,
at least one cylinder liner having a scavenge port at a lower end and an exhaust valve at an upper end;
a reciprocating piston within the at least one cylinder liner, the reciprocating piston being connected to a reciprocating crosshead by a piston rod;
A source of pressurized cooling and lubricating medium;
a telescopic tube fluidly connecting the source to an inlet port of the reciprocating crosshead ;
a conduit extending from said inlet port to said reciprocating piston ;
a valve configured to permit flow of the cooling and lubricating medium from the source to the telescopic tube and to prevent or restrict flow of the cooling and lubricating medium from the telescopic tube to the source;
Equipped with
the valve having a movable valve member arranged for movement between a closed or restricting position on a first valve seat and an open position on a second valve seat;
the movable valve member is biased toward the open position by gravity alone;
institution. the at least one cylinder liner is supported by a cylinder frame;
the telescopic tube comprises a fixed tube physically coupled to the cylinder frame and a movable tube physically coupled to the reciprocating crosshead ;
The engine of claim 1. The engine of claim 2, wherein the valve is disposed upstream of the fixed pipe or at the inlet of the fixed pipe. 4. An engine according to claim 1, wherein the movable valve member is received in a cavity within the valve body. The engine according to any one of claims 1 to 3, wherein the valve is a check valve. 4. An engine according to claim 1, wherein the conduit passes through the reciprocating crosshead and the piston rod. the at least one cylinder liner is supported by a cylinder frame;
the telescopic tube comprises a fixed tube physically coupled to the cylinder frame and a movable tube physically coupled to the reciprocating crosshead;
the movable tube is physically coupled to a guide shoe of the reciprocating crosshead ;
The engine of claim 1.

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