JP4597255B2 - Crosshead type large uniflow 2-cycle diesel engine - Google Patents

Abstract

A large uniflow two-stroke diesel engine (1) of the crosshead type with a plurality of cylinders with at least one exhaust valve (11) per cylinder and one or more fuel injectors per cylinder. The fuel injection is performed under the influence of a source of high pressure fluid. Potential energy is accumulated by compression in a volume (67) of the high pressure fluid. Electro-hydraulic valves (41) control the fuel injection that is primarily driven by energy accumulated in the volume of high pressure. The engine has a camshaft (28) for actuation of the exhaust valves (11). Hydraulic piston pumps (37) are driven by the cams (29) on the camshaft (28). Hydraulic actuators (21) move the exhaust valves in the opening direction with hydraulic fluid received via conduits (35) from the hydraulic piston pumps.

Description

  The present invention relates to a crosshead large low-speed uniflow two-cycle diesel engine, and more particularly to an engine component related to fuel injection and exhaust valve operation.

Typically, a crosshead type large two-cycle diesel engine is used as a marine propulsion or a power plant prime mover. Only the size is very large is not the cause but the structure of these heat engine also differs from any other heat engine. Due to the two-cycle principle and the use of heavy oil with a viscosity of up to 700 cSt at 50 ° C (heavy oil is non-flowable at room temperature), it belongs to a unique class in the engine industry.

  In many conventional engines of this type, the exhaust valve and fuel injection system are driven by a rotating cam that is directly connected to the crankshaft of the engine. Two-cycle engines use scavenging ports to control intake to the cylinders, and consequently intake timing is strongly related to crank angle.

  The fuel consumption, reliability and power requirements of this type of engine are extremely high. In recent years, there has been a strong demand for reducing exhaust gas emissions due to environmental requirements. In order to meet these contradictory requirements in some cases, flexible control over the fuel injection timing and fuel injection amount, and the opening of the exhaust valve, which is not possible with the conventional exhaust valve and fuel injection device driven by a rotating cam, It is believed that complete and flexible control over the degree and timing of opening and closing is necessary.

  A crosshead type large uniflow two-cycle diesel engine is known in the MC-C engine series format of MAN B & W Diesel (registered trademark). The engine is provided with a camshaft that extends to the camshaft housing along the length of the engine. The cam shaft is provided with a cam for fuel injection and a cam for exhaust valve operation.

One fuel cam per cylinder is provided on the camshaft. Each fuel cam acts on a piston-type fuel pump (one piston pump for each cylinder) which is a variable displacement type in order to adjust the amount of fuel injected for each engine cycle. The outlet of the piston pump is connected via a high pressure conduit to the injector inlet associated with the corresponding cylinder. Rate adjustments (eg, profile and timing with respect to the amount or pressure of fuel injected during the engine cycle time) are possible only by cam profile and injector characteristics, which cam profile and injector characteristics are: It cannot be easily changed after engine configuration.

  One exhaust cam is provided on the camshaft for each cylinder. The exhaust cam acts on a so-called “hydraulic push rod”. For example, exhaust valve opening profiles such as exhaust valve opening timing, exhaust valve closing timing, and exhaust valve opening extension are all determined during the construction of the engine and cannot be easily changed later.

  Emission requirements applicable to large two-cycle diesel engines operating on ocean-going vessels are determined by an international organization called IMO. In addition, local authorities can present local requirements. These emission requirements are steadily becoming more restrictive and are not always fully predictable. The allowable discharge level can be determined by the distance from the shore. Thus, the engine can be operated offshore with a higher emission level than coastline operation.

  Electronically controlled engines were developed in the 80s and 90s of the 20th century to make it possible to meet current and future emission levels.

  The MAN B & W Diesel A / S® ME engine series is a crosshead large two-cycle diesel engine with an electrohydraulic controlled exhaust valve and electrohydraulic operated fuel injection. The hydraulic system operates with oil from the engine lubrication system. The lubricating oil system operates with a 3 to 4 bar low pressure pump. Another high pressure pump supplies lubricating oil to the common rail at about 200 bar. Lubricating oil from the common rail is guided to the fuel intensifier through a hydraulic valve. This fuel booster raises the pressure of 200 bar in the common rail from the required maximum of 800 bar to 1000 bar in the fuel path. The fuel path is heated to ensure that the fuel has fluidity and proper viscosity. Lubricating oil from the common rail is guided to the hydraulic exhaust valve actuator via the timing valve to operate the exhaust valve.

  The fuel system uses hydraulic fluid (same as lubricating oil in this engine) from a hydraulic power system that drives a pressure booster that provides high pressure fuel (heavy oil) to the injector. One intensifier is provided per cylinder. The high pressure side of the intensifier pressurizes the fuel from the required level of about 800 bar to 1000 bar. An electronically controlled hydraulic proportional valve allows for rate shaping and timing of the injected fuel. Therefore, rate adjustment and timing changes are very easy even after engine configuration, and may be applied even during engine operation, depending directly on changing conditions such as load or operating speed. .

  The hydraulic cylinder actuator is mounted on each exhaust valve, and a high pressure hydraulic medium is provided from a high pressure hydraulic supply system via an electronic control valve. The exhaust valve is biased in the closing direction by a gas spring. The timing of the exhaust valve opening movement and the exhaust valve closing movement, and the opening extension of the exhaust valve can be controlled by an electronic control valve. Therefore, it is very easy to change the timing of the exhaust valve and the opening extension even after the engine is configured.

  Both fuel injection and exhaust valve actuation are controlled by a programmable controller with appropriate software.

  Thus, electronically controlled engines have additional degrees of freedom in their settings, making it easier to meet the requirements imposed on engines that are numerous and often contradictory. Operators of such engines require unique high power, high fuel efficiency, and high reliability at low construction costs. In many cases, emission requirements limit maximum combustion pressure and maximum combustion temperature, as well as other aspects that increase fuel efficiency and power. As a result, the problem of determining such an optimal operation setting of the engine is required for engineers who develop this type of engine. Increased degrees of freedom in engine settings and increased flexibility in changing the settings of such engines during engine operation or engine lifetime will provide significant advantages to electronically controlled engines over camshaft engines. It is.

  However, the installation cost of electronically controlled fuel injection and exhaust valve actuation is relatively high and is relatively independent of engine size. This means that it does not follow the normal pattern that generally applies to many of the other components of such engines, where the larger engine will increase the cost of these components. In fact, this is because a super-large engine with a piston diameter of more than about 90 cm can be built cheaply with an electronically controlled fuel injection and exhaust system, while a small piston diameter of less than about 60 cm. This means that, in contrast to the camshaft operating model, such an engine is very expensive when equipped with an electronic fuel injection and exhaust valve actuation system.

Low construction costs that are competitive with small caliber engines are paramount to market success. Thus, the output and fuel consumption, reliability, necessary to meet the requirements at the discharge limit, the contact Keru freedom and flexibility in operating condition setting, can be realized at a cost comparable to conventional camshaft engine levels, about There is a need for a large two-cycle diesel engine having a piston diameter of less than 60 cm.

In this context , there is also a need for reduced cost and complexity and improved reliability associated with hydraulic systems associated with electronic fuel control systems for large two-cycle diesel engines.

  From such a background, an object of the present invention is to provide a crosshead type large uniflow type two-cycle diesel engine capable of realizing the above-mentioned demand.

This object is achieved by a plurality of cylinders having at least one exhaust valve, respectively, a fuel injection device provided at least one for each cylinder, a high pressure fluid fluid source and capable of storing potential energy by compressing the bulk / or an accumulator capable of accumulating the potential energy by compression, a crosshead-type large uniflow two-stroke diesel engine equipped with at least one electronically controlled hydraulic valve, the fuel injection is primarily driven by stored potential energy The fuel injection is controlled by at least one hydraulic valve, and at least one camshaft provided with a cam for the operation of at least one exhaust valve associated with each of the cylinders, each with a corresponding cam on the camshaft Multiple hydraulic piston pumps driven A hydraulic actuator provided for each exhaust valve for moving the exhaust valve in the opening direction, a hydraulic conduit for connecting the hydraulic piston pump to the hydraulic actuator, provided for each exhaust valve, and provided for each exhaust valve This is achieved according to claim 1 by providing an engine further comprising an elastic member for biasing the exhaust valve in the closing direction.

The inventors of the present application have noticed that the advantages of an electronically controlled engine are biased towards the fuel injection aspect. Electronic fuel injection provides considerable flexibility in determining the optimal operating parameters of the engine, considers meeting current emission requirements, and the engine may need to comply later in its lifetime Considering the flexibility to the emission requirements, considerable flexibility is provided. By separating the hydraulic pressure from the exhaust valve actuation system, the fuel injection pressure can be selected more freely. This improves the possibilities for the ideal injection pressure in all situations. Currently available electronic control exhaust valve actuation system for use a substantial amount of hydraulic power, and reduces the overall fuel efficiency of the engine.

Since the exhaust valve is based on camshaft control , the need for overall oil pressure is reduced compared to an engine that performs electronic injection and fuel injection and valve actuation. This makes it possible to meet the need for hydraulic pressure with smaller pumps that are typically available in the industry as electric pumps. It is clear that such an electric pump is a significant cost reduction compared to the installation cost of a large hydraulic pump driven by power from the engine crankshaft.

Preferably, the high pressure fluid is a medium different from the fuel and is separated from the fuel. In this case, the high pressure fluid and the fuel are separated by at least one piston device provided for each cylinder, and the high pressure fluid moves the piston device during fuel injection, and then the piston device moves to the combustion chamber in the corresponding cylinder. Move the fuel to

The piston device may be a pressure intensifier, and the piston device preferably includes a piston having a large effective area facing the high pressure hydraulic fluid and a small effective area facing the fuel. This makes it possible to use a hydraulic medium that operates at a pressure significantly lower than the injection pressure.

Preferably, a predetermined amount of high-pressure fluid is contained in a supply conduit that extends along the length of the engine. The supply conduit comprises a plurality of compression chambers distributed along the length of the engine, so that the compression chamber is for high pressure hydraulic fluid so that a considerable amount of potential energy can be stored by compression of the hydraulic fluid itself. Of sufficient volume . This feature is advantageous because the use of membrane accumulators can be avoided, and membrane accumulators tend to suffer problems.

  Preferably, one compression chamber is provided for supplying high pressure hydraulic fluid to a pair of adjacent cylinders.

  The engine further includes a camshaft housing that houses a camshaft and a supply conduit. Thus, the supply conduit is housed in place shielded from damage, and the camshaft housing protects people near the supply conduit from the risk of rupturing the supply conduit filled with high pressure fluid.

  Preferably, the compression chamber is at least partially disposed within the camshaft housing. Therefore, the engine is organized by the compression chamber.

  The compression chamber may share at least a portion of one wall with the camshaft housing to reduce the amount of engine building material.

  Preferably, the compression chamber is formed by aligning the recess with a solid metal block so that the compression chamber is exposed during its lifetime and resists variable high pressure.

  The fluid source of high pressure fluid may be one or more electric high pressure pumps. The use of an electric high pressure pump makes it easier to start the engine since there is no need for a separate starter pump for the fuel system.

  Preferably, one hydraulic valve controls fuel injection for two or more engine cylinders. Thus, the number of electronically controlled hydraulic valves required for engine construction is reduced. The reduction in required control capacity is particularly relevant for smaller engines that are sensitive to size-independent costs.

  According to a preferred embodiment, the high pressure hydraulic fluid is a fuel. In this embodiment, it is preferable that a predetermined amount of high-pressure hydraulic fluid is accommodated in the common rail.

  The hydraulic valve used for injection control is preferably a proportional valve. The hydraulic valve is controlled by one or more computers. The one or more computers are configured to adapt fuel injection timing and / or rate adjustments to engine operating conditions. This feature easily optimizes engine performance with respect to power, reliability, reactivity, and emissions.

  One or more computers are configured to advance fuel injection timing when the engine load is decreasing. Thus, the maximum fuel pressure can be maintained at a high level during low load conditions.

  Preferably, the rate of fuel injection is adjustable during fuel injection to obtain the desired injection profile. This feature increases the freedom of engine settings and easily optimizes engine performance with respect to power, reliability, reactivity, and emissions.

  The engine may further comprise a cylinder lubrication system that is also controlled by one or more computers. In this case, the high pressure hydraulic fluid may also power the cylinder lubrication system. An electronically controlled cylinder lubrication system makes it possible to quickly adapt to changing fuel quality. Thereby, when the engine is operating with high quality fuel (eg, low sulfur content fuel), it is possible to save a substantial amount of cylinder oil that results in the next largest variable operating cost of fuel consumption. .

  Preferably, the high pressure conduit connecting the hydraulic piston pump to the valve actuator is such that the exhaust valve can initiate its return process prior to the return process timing defined by the corresponding cam on the camshaft. The pressure can be reduced by electronic control valve means. Therefore, some flexibility is obtained in the operation of the exhaust valve, and the degree of freedom in setting the engine operation is increased.

  Preferably, the high pressure conduit connecting the hydraulic piston pump to the valve actuator can be selectively interrupted by electronic valve means to delay the return process from the return process timing defined by the corresponding cam on the camshaft. is there. Therefore, some flexibility is obtained in the operation of the exhaust valve, and the degree of freedom in setting the engine operation is increased. The one or more computers may be configured to control the advance or delay of the timing of exhaust valve closure in relation to engine operating conditions.

  The camshaft may be provided with a mechanism for adjusting the angular position of the crankshaft with respect to the angular position of the crankshaft, and the mechanism is provided with an additional computer for changing the opening / closing timing of the exhaust valve. Is preferably controlled by one of these. Therefore, some flexibility is obtained in the operation of the exhaust valve, and the degree of freedom in setting the engine operation is increased.

A further object of the present invention is to provide a crosshead type large uniflow two-cycle diesel engine. Supply to a plurality of cylinders each having at least one exhaust valve, a camshaft housing having a camshaft for operating the exhaust valve therein, and fluid-driven engine components distributed along the length of the engine A crosshead large uniflow two-cycle diesel engine comprising a high pressure hydraulic system for supplying high pressure fluid through a conduit, wherein the supply conduit is disposed within a camshaft housing by providing an engine This is achieved according to claim 25.

  By placing the supply conduit inside the camshaft housing, the camshaft housing wall protects engine personnel from the risk of rupture of the high pressure supply conduit, thus eliminating the need for a double wall supply conduit.

  The supply conduit can be used to supply high pressure fluid to the electronic fuel injection system.

  The supply conduit may also be used to supply high pressure fluid to the electronic cylinder lubrication system.

Yet another object of the present invention is to provide a crosshead large uniflow two-cycle diesel engine having an electronic fuel injection system with improved reliability and robustness. The present invention includes a plurality of cylinders having at least one exhaust valve per cylinder, one or more fuel injectors per cylinder, a fluid source of high pressure fluid, and a predetermined amount of high pressure at which potential energy is accumulated by compression. A crosshead type large uniflow two-stroke diesel engine comprising a fluid and at least one electronically controlled hydraulic valve, wherein the predetermined amount is contained in a supply conduit extending along the engine adjacent to the cylinder. The supply conduit comprises a plurality of compression chambers having a sufficient volume to increase the amount of potential energy that can be stored in the predetermined amount, and the fuel injection is mainly driven by the energy stored in the predetermined amount. Claimed by providing an engine that is driven and the fuel injection is controlled by the at least one hydraulic valve It is achieved in accordance with 28.

The compression chamber has a sufficient volume to store potential energy in the hydraulic fluid so that the maximum required hydraulic fluid flow rate is available during the entire fuel injection process. The volume of fluid in the supply conduit itself is not sufficient for this purpose. By using a compression chamber with an enlarged volume, the use of a membrane accumulator with a gaseous medium that accumulates in potential energy can be avoided.

  Preferably, one compression chamber is provided for supplying high pressure hydraulic fluid to a pair of adjacent cylinders. Therefore, the number of compression chambers can be minimized, so that installation costs are reduced.

  The compression chamber can be formed by matching a recess, preferably a cylindrical recess, in a solid metal block.

  Further objects, features, advantages, and characteristics of the crosshead large uniflow two-cycle diesel engine according to the present invention will become apparent from the detailed description.

Detailed Description of the Preferred Embodiment

  In the following detailed description portion of the specification, the present invention will be described in more detail with reference to exemplary embodiments shown in the drawings.

1 and 2 show an engine 1 according to a preferred embodiment of the invention in a front cross-sectional view and one cylinder as viewed from the side of the engine. The engine 1 is a crosshead type uniflow low-speed two-cycle diesel engine, and can be a propulsion system of a ship or a prime mover of a power plant. Typically, such engines have from 3 to a maximum of 14 cylinders in a row. The engine 1 is assembled from a base plate 2 having a main bearing for the crankshaft 3.

  The crankshaft 3 is a semi-assembled type. The semi-assembled mold is manufactured from a cast steel throw or forged steel throw connected to the main journal shaft by shrink fitting.

  The base plate 2 can be manufactured as one part, or can be divided into parts of an appropriate size according to the manufacturing facility. The base plate is made from a highly welded longitudinal girder and a welded cross girder with cast steel bearing support. Alternatively, the base plate may be a cast design. An oil pan that is integral with the base plate in the casting design collects the return oil from the forced lubricant and cooling oil system.

The connecting rod 8 is made of cast steel or forged steel, and includes a bearing cap (for a crosshead bearing and a crankpin bearing). The cross head and the crank pin bearing cap are fixed to the connecting rod 8 by studs and nuts. The stud and nut are tightened by a hydraulic jack. The crosshead bearing 22 includes a set of thin iron shells lined with bearing metal . The crankpin bearing is provided with a thin-walled iron shell lined by a bearing metal . Lubricating oil is supplied through a duct (not visible in the drawing) in the crosshead 22 and the connecting rod 8.

The main bearing includes a set of thin iron shells lined with bearing metal . With a special tool and a hydraulic tool for raising the crankshaft, the bottom shell can be rotated in and out. The shell is maintained in place by a bearing cap (not shown).

A welded A-type frame box 4 is mounted on the base plate. The frame box can be a casting design or a welding design. The exhaust side frame box is provided with an open valve for each cylinder, while the camshaft side frame box is provided with a large hinged door for each cylinder. The crosshead guide is integrated with the frame box .

The cylinder frame 5 is mounted on the upper part of the frame box 4. Retaining bolts (not shown) connect the base plate 2 to the cylinder frame 5 and maintain the structure in an integrated manner. The reserve bolt is tightened with a hydraulic jack.

The cylinder frame 5 is cast with the camshaft housing 25 as one or more parts, or manufactured by welding . The camshaft housing 25 is welded / bolted there, or is integral with the cylinder frame as shown .

The cylinder frame 5 is provided with an access cover for cleaning the scavenging space and checking the scavenging port on the camshaft side and the piston ring. The cylinder frame forms a scavenging space together with the cylinder liner 6. The scavenging receiver 9 is bolted to the cylinder frame 5 on its open side. At the bottom of the cylinder frame is a piston rod stuffing box, which is provided with a scavenging sealing ring and an oil ring that prevents oil from entering the scavenging space.

  The piston 13 includes a piston crown and a piston skirt. The piston crown is made of heat-resistant steel, has four ring grooves, and hard chrome is plated on the upper and lower surfaces of the groove portions.

  The piston rod 14 is connected to the crosshead 22 by four screws. The piston rod 14 has a central hole (not visible in the drawing) and is connected to a cooling oil pipe to form an inlet and an outlet for the cooling oil of the piston 13.

  The crosshead 22 is made of forged steel, and has a cast steel sliding metal containing a white alloy on its operating surface. The oil inlet telescopic tube (not visible in the figure) and the oil outlet tube are mounted on a sliding metal.

The cylinder liner 6 is a uniflow type and is carried on the cylinder frame 5. The cylinder liner 6 is made of alloy cast iron and is suspended from the cylinder frame 5 by a flange at a low position. The top of the liner is surrounded by a cast iron cooling jacket. The cylinder liner 6 has an exhaust port 7 and a drill hole (not shown) for cylinder lubrication.

  The camshaft 28 is incorporated in a bearing shell lined with a white alloy in the camshaft housing 25. The cam shaft 28 is integrated with an exhaust cam, an instruction cam, a thrust disk, and a chain wheel that are shrink-fitted on the shaft. The exhaust cam is made from steel with a hardened roller race. They can be adjusted and disassembled hydraulically.

  The cylinder 6 is a uniflow type and has a scavenging port 7 positioned in the air box 5 ′. The exhaust port is supplied with scavenged air pressurized by the turbocharger 10 (FIG. 1) from the scavenging receiver 9 (FIG. 1).

  The intake air to the turbocharger 10 is generated directly from the engine compartment via an intake silencer (not shown) of the turbocharger. Air is guided from the turbocharger 10 to the scavenging port 7 of the cylinder liner 6 through an air supply pipe (not shown), an air cooler (not shown), and a scavenging receiver 9.

  The engine is equipped with one or more turbochargers. The turbocharger is arranged at the aft end in the case of an engine having 4 to 9 cylinders and on the exhaust side in the case of 10 or more cylinder type engines.

The engine is provided with an electric scavenging blower (not shown). The suction side of the blower is connected to the next scavenging space of the air cooler. A check valve (not shown) is mounted between the air cooler and the scavenge receiver, and the check valve automatically closes when the auxiliary blower supplies air. The auxiliary blower assists the turbocharger compressor in low and medium load conditions.

  The exhaust valve 11 shown in detail in FIG. 3 is mounted at the center of the cylinder upper portion of the cylinder cover 12. At the end of the expansion stroke, before the piston 13 of the engine descends over the scavenging port 7, the exhaust valve 11 opens, so that the combustion gas in the combustion chamber 15 on the piston 13 is released to the exhaust receiver 17. And the pressure in the combustion chamber 15 is released. The exhaust valve 11 closes again during the upward movement of the piston 13. The exhaust valve 11 is driven upward by a pneumatic spring 20.

The exhaust valve 11 is opened by the cam shaft 28. This camshaft is disposed in a camshaft housing 25 that extends along the length of the engine adjacent to the cylinder frame 5. Also disposed in the camshaft housing 25 is a high pressure supply conduit 30 of a hydraulic system associated with a fuel injection system (described in more detail below). The supply conduit 30 extends substantially over the entire length of the engine. Since the supply conduit 30 is located within the camshaft housing, it is not necessary to use a double wall for the supply conduit 30 , but if not placed within the camshaft housing, the highly pressurized supply conduit 30 will rupture A double wall is required to protect the engine operator when doing so.

  3 and 4 show the cylinder liner 6, the cylinder cover 12, and the upper part of the exhaust valve housing. The cylinder cover 12 is made of forged steel manufactured as an integral type, and has a hole for cooling water. The cylinder cover 12 includes a central hole for the exhaust valve 11, two or three fuel injectors 23, a safety valve (not shown), a start valve (not shown), and a shiatsu valve (not shown). And a hole for. Each cylinder cover 12 is equipped with two or three fuel injectors 23, one start valve, one safety valve, and one shiatsu valve. Opening of the fuel injector 23 is controlled by high pressure fuel oil generated by a fuel intensifier (described in more detail later), and the fuel injector 23 is closed by a spring. Automatic slide holes (not shown) allow fuel oil to circulate through the fuel injector and fuel oil to circulate through a high pressure pipe connecting the fuel injector 23 to the fuel intensifier. Further, the automatic slide hole prevents the fuel oil from overflowing into the combustion chamber 15 when the spindle of the injector 23 does not move when the engine 1 is stopped. Oil from slide holes and other tubes is directed into the closed system.

The exhaust valve housing is made of cast iron and is arranged to cool the water. The housing is provided with a steel bottom part, and overlay metal is welded to the seat. The bottom part is cooled by water. The valve spindle itself is made of heat-resistant steel, and overlay metal is welded to the seat. A spindle guide is provided in the exhaust valve housing. The exhaust valve housing is fastened to the cylinder cover 12 by retaining bolts and nuts. The hydraulic exhaust valve actuator 21 is mounted on the upper part of the exhaust valve housing. When pressurized, the exhaust valve is urged downward (opening direction) by the hydraulic actuator 21. The hydraulic actuator 21 includes a piston in a cylinder, and a pressure chamber on the piston in the cylinder. The exhaust valve housing also includes an air spring 20 that urges the exhaust valve spindle 11 upward (in the closing direction). The air spring 20 includes a spring piston, and the spring chamber is disposed below the spring piston in the cylinder of the exhaust valve housing.

The hydraulic exhaust valve actuator 21 of each exhaust valve is connected to a piston pump 37 (FIG. 6) via a pressure pipe 35. In this embodiment, there is one piston pump 37 and one exhaust valve 11 per cylinder, but there may be multiple piston pumps or multiple exhaust valves per cylinder (not shown).

  As shown in FIG. 7, a piston pump 37 is mounted on the roller guide housing 46. The roller 42 follows each cam 29 of the cam shaft 28. Accordingly, the piston pump 37 is actuated by the camshaft 28.

  FIG. 5 is a perspective view of the engine, with some components omitted for illustrative purposes. The camshaft 28 is driven by a chain drive 26 that connects the camshaft 28 to the crankshaft 3. The chain drive 26 is provided with a chain fastening (not shown) and a guide rod (not shown) to support a long chain length. According to a variant of this embodiment, the chain drive powers a hydraulic pump (not shown) for the high pressure oil pressure of the engine. The chain also serves to drive the secondary counterweight. As an alternative to chain drive, the camshaft can be driven by transmission with a gear (not shown).

FIG. 6 shows a portion of FIG. 5 and shows the camshaft housing 25 and cylinder 6 in more detail. In this figure it can be seen that the conduit 31 branches off from the supply conduit 30. Conduit 31, through a distributor block 40 having a hydraulic control valve 41 connects the feed conduit 30 to the pressure booster 39. The distributor block 40 is attached to the top plate portion of the camshaft housing 25.

A piston pump 37 that is actuated by the cam 29 of the cam shaft 28 is also disposed on the top plate portion 25 ′ of the cam shaft housing 25. The piston pump 37 is connected to the hydraulic exhaust valve actuator 21 via the pressure pipe 35.

  Each cylinder 6 is provided with two or three injectors 23, each connected to a conduit (not shown in FIG. 6 but indicated by reference numeral 51 in FIG. 8) to provide one of the pressure boosters 39. Or connect to multiple ports.

  Each distributor block 40 carries two proportional control valves 41. This proportional control valve 41 controls the connection between the upper port of the distributor block 40 and the return conduit (65 in FIG. 8) and the supply conduit 30 in the camshaft housing 25. The intensifier 39 is mounted on the upper part of each distributor block 40 and communicates with a port on the upper part of the distributor block 40. Thus, the distributor block 40 serves as a mechanical support for the hydraulically actuated fuel booster 39.

7A, 7C, and 7C show in detail a perspective view of the compression chamber housing 68 in different cross-sectional views. The compression chamber 67 has a sufficient capacity to store potential energy in the hydraulic fluid, and can receive the required maximum flow rate of the hydraulic fluid during the entire fuel injection process.

In this embodiment, one compression chamber housing 68 with two compression chambers 67 is provided for each adjacent pair of cylinders 6; however, the number of compression chambers per cylinder may be increased or decreased.

The compression chamber 67 is supplied with high-pressure hydraulic fluid from the supply conduit 30 via a locally branched conduit 31. The connection between the conduit 31 and the conduit 30 is realized by a connecting block 30 ′ attached to the bottom of the camshaft housing 25.

The compression chamber housing 68 is formed as a part integrated with the top plate portion of the camshaft housing 25. The top plate portion of the camshaft housing 25 is divided into a plurality of portions in the longitudinal direction. One such type of part is a metal slab with two cylindrical compression chambers 67 formed therein, which also forms a compression chamber housing 68. The top plate portion also carries a distributor block 40 in which the pressure intensifier 39 is disposed. The longitudinal axis of the cylindrical compression chamber 67 is disposed parallel to the longitudinal axis of the cam shaft 28. The compression chamber 67 is manufactured by matching two parallel holes in a metal solid slab. The compression chamber 67 is sealed by a circular fixing plate 69 that is fastened to the compression chamber housing 68. An upward hole (not shown) through the compression chamber housing 68 connects to the compression chamber of the distributor block 40. Because the distributor block is mounted directly on top of the compression chamber housing 68, the path through which high pressure hydraulic fluid must travel from the compression chamber 67 to the distributor block 40 is very short.

  The other type of camshaft housing 25 top plate (shown in the cross-sectional view of FIG. 7) carries a piston pump 37.

  The two types of camshaft housing top plate portions are alternately arranged along the length direction of the camshaft housing 25. There is a longitudinal overlap at the transition between the two types of top plate and the top plate is fastened at this overlap.

  FIG. 8 schematically shows a fuel injection system. The fuel is supplied from the fuel supply facility 73 to the pressure intensifier 39. The fuel supply facility 73 is not shown in detail in the drawing. The fuel supply facility 73 is configured such that both diesel oil and heavy oil can be used. The fuel is led from a fuel tank to an electric supply pump, which can maintain a pressure of about 4 bar in the low pressure part of the fuel circulation system. Accordingly, fuel gasification in the venting box is avoided in the applied temperature range. The fuel oil is led from the low pressure part of the fuel system to the electric circulation pump. This electric circulation pump pumps fuel oil through a heater and a full flow filter located just before the inlet of the engine 1, where the fuel is distributed to the respective pressure boosters 39.

  The fuel injection is executed by the electronically controlled pressure booster 39 for each cylinder. The pressure booster doubles the pressure at a constant ratio from the low pressure side (the side where the hydraulic fluid is applied) to the high pressure side (the fuel side).

Fuel boosters 39 are powered by pressurized hydraulic fluid. This hydraulic fluid may be engine lubricating oil. The pressure pump 60 typically supplies several hundred bar high pressure hydraulic fluid to the cylinder via the supply conduit 30. When the hydraulic fluid is an engine lubricant, the pressure pump 60 is not an engine lubrication pump that operates at a lower pressure. The return fluid is transferred from the cylinder to the tank 61 via the conduit 65, from which the fluid is drawn by the pump 60.

A compression chamber 67 is provided for each pair of cylinders (if there is an odd number of cylinders in the engine, there may be one compression chamber for one of the cylinders). Conduit 69, the compression chamber 67 and is connected to two proportional control valves 41 and two on / off valve 55. According to a modification (not shown) of this embodiment, a gas-filled membrane accumulator is used as an alternative to the compression chamber or in addition to the compressor.

  Each cylinder 6 of the engine 1 is associated with an electronic control unit 99. This electronic control unit 99 receives general synchronization signals and control signals, and in particular transmits the electronic control signals to the proportional control valve 41 via line 59. There may be one control unit 99 per cylinder, or several cylinders may be associated with the same control unit (not shown). Further, the control unit 99 may receive a signal from a comprehensive control unit common to all cylinders (not shown).

  The control unit 99 calculates the fuel injection timing, rate adjustment, and amount in accordance with the operating state of the engine. Here, the control unit receives information on the rotational position of the crankshaft, the rotational speed of the crankshaft (which can be derived from the rotational position signal by the control unit 99), the outside air temperature, the load, and the temperature of the various engine fluids. Further, the control unit appropriately adjusts the timing of fuel injection for rotating the engine in the reverse direction. The spool movement of the proportional control valve 41 is controlled by the control unit 99 in a feedback control loop. Alternatively, this feedback control loop can be included in the proportional control valve 41 itself. The opening profile of the proportional valve 41 is adapted to a desired opening profile that is predetermined and stored in the control unit 99 for optimum rate adjustment.

  Proportional control valve 41 connects the pressure chamber to the tank in its rest position. The low pressure side of the intensifier is connected to the pressure chamber and connected to the tank. When the control unit 99 sends a signal to start fuel injection for a given cylinder, one of the proportional control valves 41 is opened to some extent, so that the low pressure side of the intensifier 39 is connected to the compression chamber 67 via the conduit 69. Connecting.

  The pressure on the low pressure side of the intensifier is amplified and typically reaches an injection pressure between about 400 bar and about 1500 bar. The supply conduit 51 transfers the high-pressure fuel to the fuel injection device 23, and the fuel injection device 23 injects the fuel into the fuel chamber 15 through the nozzle, thereby atomizing the fuel.

The control unit 99 controls the on / off valve 55. This on / off valve 55 controls the supply of high-pressure fluid to the cylinder lubricator 57. Based on the operating state and the position of the crankshaft, the control unit 99 determines the timing and amount of lubricating oil that is pumped into the cylinder. On / off valve 55 is in its rest position, connects the cylinder lubricators 57 to tank 61. When a given on / off valve 55 receives a signal from the control unit 99 that pumps lubricating oil into a particular cylinder, the on / off valve 55 connects the cylinder lubricator 57 to the compression chamber 67 via a conduit 69. The cylinder lubricator starts pumping lubricating oil into the cylinder. The control unit 99 determines the amount of lubricating oil that is pumped into the cylinder via the length of operation of the on / off valve 55.

  FIG. 9 shows an exemplary rate adjustment profile for the fuel injection process. The pressure increase is intentionally gentle and slow so as to maintain a substantially uniform and high combustion pressure for a long time, which is close to the maximum allowable combustion pressure under full load.

Figures 10 and 11 illustrate another embodiment of the present invention. In this embodiment, the electronic fuel injection is a so-called common rail type. In this system, there is no separate hydraulic fluid, but instead the fuel is maintained at high pressure and the energy for injection is saved by compression of the fuel. Common rail is divided into a plurality of portions 95 which are respectively associated with two cylinders. The advantage of this configuration lies in the further improvement of the common rail that adapts to the torsional motion of the engine 1 during engine operation. Without this configuration, very long and seamless common rail tubes can deform and be subject to fatigue.

FIG. 12 schematically shows a common rail injection system. Typically, the engine operates on heavy fuel oil (HFO) (both water and non-water emulsification). Emulsification is carried out in a separate emulsification unit (not shown). Fuel for engine operation is stored in the heating tank 129. The viscosity of HFO is 500 cSt to 700 cSt at 50 ° C. and cannot flow at room temperature. The HFO in the tank is maintained at about 50 ° C at all times, that is, even when the engine is stopped. Typically, ships equipped with this type of engine are provided with a generator set (power generation set), i.e. a smaller diesel engine, which allows the ship and Power and heat are provided to the engine. From the heating tank 129, the HFO is directed to a filter or centrifuge 130 and a preheater 131. The temperature of the HFO exiting the preheater 131 is controlled depending on the operating conditions and the HFO grade. When the HFO is circulated at low pressure through the hydraulic system while the engine is stopped, the HFO temperature is maintained in the range of 45 ° C to 60 ° C. During engine operation, the temperature of the HFO exiting the preheater 131 is maintained between 90 ° C and 150 ° C depending on the viscosity of the HFO. A sensor (not shown) measures the viscosity of the HFO just downstream of the preheater 131 (or another suitable location). Typically, the temperature of the HFO exiting the preheater 131 is controlled to have a viscosity in the range of 10 cSt to 20 cSt at the measurement point .

Forked intermediate conduit 132, a preheater, connected to both the high-pressure fuel pump 133 and an auxiliary low pressure circulation pump 134. A check valve 135 is placed in the conduit downstream of each pump to prevent reverse suction.

  During engine operation, the high pressure fuel pump 133 is driven by a gear 136 on the crankshaft 3 via a gear 137. Here, the high pressure fuel pump 133 generates a nominal pressure of 1000 bar to 1500 bar, but the pressure may vary between 600 bar and 2000 bar depending on the operating conditions.

The auxiliary low pressure circulation pump 134 is driven by the electric motor 138 while the engine is stopped. Here, while the engine is stopped, through the hydraulic system to circulate the HFO, a pressure of about 3 bar to about 10 bar is supplied.

The common fuel rail 140 extends along all cylinders, and the connection with the cylinder 6 is not shown in FIG. 12, but is indicated by a short upward line extending from the common rail. The common rail need not be formed by a single long tube extending along the length of the engine. Alternatively, the common rail may be divided into mutually continuous portions , each including several cylinders, as shown in FIGS.

HFO is supplied to a pair of adjacent cylinders via a supply conduit 141 branched from the common rail 140 and connected to the inlet port of the proportional control valve 125. The supply conduit 141 is provided with a number of fluid accumulators 142 that supply the majority of the fluid volume when the proportional control valve 125 is open and then from the common rail 140 during the closing of the proportional control valve 125. Supplied.

Supply conduit 120, one of the two outlet ports of the proportional control valve 125 is connected to one of the injector 23 of the two adjacent cylinders. Another feed conduit 124, the other of the two outlet ports of the proportional control valve 125 is connected to the other of the injector 23 of the two adjacent cylinders. Proportional control valve 125 also has two tank ports connected to return conduit 143 for the return HFO.

The proportional control valve 125 is a solenoid driven spool valve having three main positions. Solenoid 144 receives a control signal from control unit 99 via line 128. According to another embodiment (not shown), the solenoid 44 is connected to the valve housing via an insulating spacer.

In the neutral position where the solenoid 144 is not activated, the inlet port of the proportional control valve 125 is closed and the two outlet ports of the proportional control valve 125 are connected to the return conduit 143.

When the solenoid is operated to bias the spool valve to the left (left in FIG. 12), the proportional control valve inlet port is connected to the supply conduit 120 and is one of the two cylinders associated with the control valve 125. The injector 23 injects fuel into the combustion chamber 15 in FIG. In this position, the pressure conduit 124 is connected to the return conduit 143.

When actuating solenoid 44 to bias the spool valve to the right (right in FIG. 12), the inlet port of proportional control valve 125 is connected to supply conduit 124 and is connected to two cylinders associated with proportional control valve 125. A high pressure HFO is passed so that the injector 23 injects fuel into the combustion chamber 15 on the other side. In this position, the pressure conduit 120 is connected to the return conduit 143.

  The fuel injection timing, the injected fuel volume, and the shape of the injection pattern are controlled by the proportional valve 125.

In a not shown variant of this embodiment, one proportional control valve with a small number of ports and only two positions is used to control fuel injection for one cylinder. In this variation, the proportional control valve connects the feed conduit to the low-pressure circuit in its rest position, and in one of its two positions, to connect the feed conduit to the common rail.

  In another variation, not shown, of this embodiment, the common rail at the interrupted portion does not include gas filled membrane accumulators 142 and 148.

According to a further preferred embodiment (not shown), the fuel flow from the common fuel rail to the injector is controlled by an on / off valve .

An existing fuel limiter 146 is provided in both supply conduits 120, 124 to avoid exceeding the amount of HFO entering the cylinder if the proportional control valve 125 is accidentally opened too long.

The pressure in the return line 143 is maintained at an overpressure of a few bars to prevent air from penetrating the hydraulic system and to prevent water contained in the water emulsified HFO from generating steam bubbles. A pressure control valve 147 at the downstream end to the return conduit 143 allows a predetermined minimum overpressure to be maintained in the return conduit 143. The overpressure in the return conduit 143 is preferably 3 to 10 bar. An accumulator or expansion vessel 148 is connected to the return conduit 143 to absorb pressure fluctuations that can occur as the proportional control valve 125 changes position.

The second return conduit 149 is connected to the outlet port of the injector 23 and leads to the return conduit 43. Downstream of the pressure control valve 147, the return conduit 143 supplies spent HFO to the preheater 131 to complete the cycle.

A heating means represented by a heating coil is provided in the HFO from the outlet of the preheater 131 to the common rail 140 and the conduit that transfers the HFO from the common rail 40 to the injector 23 via the proportional control valve 125. The conduit can be heated over its entire length, for example, by a steam trace or an electrical heating element. Heating these conduits serves to reduce heat loss as hot HFO moves downstream from the preheater. During engine operation, the temperature of the HFO in the conduit to the injector and hydraulic valve actuator is maintained near 150 ° C, but depends on the viscosity of the HFO used. Adjacent conduits parallel to a portion of their length, such as supply conduit 120 and supply conduit 124, may be provided with a common heating means (not shown).

  The return pipes 143 and 149 are provided with the same type of heating means as described above. The HFO temperature in the return line is not critical and the heating means is calibrated so that the HFO temperature does not fall below 50 ° C.

  While the engine is stopped, the HFO circulates through the hydraulic system with a circulation pump 134 (at a relatively low pressure of 3 bar to 10 bar), avoids air entrapment in the hydraulic system, and also provides local cooling of the HFO and Avoid curing.

According to a variant of the above embodiment (not shown), the high-pressure conduit 35 connecting the hydraulic piston pump 37 to the valve actuator 21 can be depressurized by electronic control valve means (controlled by the control unit 99) and exhausted. The valve allows the return process to be initiated prior to the return process timing defined by the respective cam of the camshaft.

According to a further variant of the above embodiment (not shown), the high-pressure conduit 35 connecting the hydraulic piston pump 37 to the valve actuator 21 can be selectively interrupted by electronic valve means (controlled by the control unit 99). ), The return process is delayed until after the return process timing defined by each cam of the camshaft.

One or more control units 99, in connection with the operation of the engine may be configured to control the advanced or delayed timing of the closing of the exhaust valve.

  According to yet another modification (not shown) of the above embodiment, the camshaft 28 is provided with an electrohydraulic mechanism for adjusting the angular position of the camshaft 28 with respect to the angular position of the crankshaft 3. This mechanism is controlled by one of the additional control units 99 to change the timing of opening and closing the exhaust valve.

  Although the preferred embodiment shows only an engine in which the cylinders are arranged in a row, the present invention can also be used with other cylinder arrangements such as a V or U configuration.

  The term “comprising”, used in the claims, does not exclude other elements or steps. The singular terms used in the claims do not exclude the plural.

  Any reference signs used in the claims shall not be construed as limiting the scope.

  Although the present invention has been described in detail for purposes of illustration, such details are not merely for purposes of this invention and can be modified by one skilled in the art without departing from the scope of the invention. Please understand that.

It is sectional drawing of the engine according to this invention seen from the front of the engine. FIG. 2 is a cross-sectional view of one cylinder portion of the engine shown in FIG. 1 as viewed from the side of the engine. FIG. 2 is a detailed view of FIG. 1. FIG. 3 is a detailed view of FIG. 2. FIG. 2 is an elevational perspective view of the engine of FIG. 1. FIG. 6 is a detailed view of FIG. 5. 2 shows a cross-sectional detail of the exhaust valve actuation system of the engine of FIG. 1 in a first position along the camshaft. FIG. 2 shows a cross-sectional detail of the valve actuation system of the engine of FIG. 1 in a second position along the camshaft. It is sectional drawing of the whole camshaft housing in the surface parallel to the longitudinal direction axis | shaft of a camshaft. It is a perspective view regarding the detail of a cam shaft housing. 2 is a schematic representation of the fuel injection system and valve actuation system of the engine of FIG. 2 is a graph showing a rate adjustment profile for fuel injection of the engine according to FIG. 1. FIG. 2 is an elevational perspective view of the engine of FIG. 1 in another embodiment. Details of FIG. 10 are shown. FIG. 11 is a schematic representation of a fuel injection system according to the embodiment of FIG.

Claims (24)

A base plate, a frame box placed on the base plate, a cylinder frame mounted on the frame box,
A camshaft housing that is integrated with, welded to, or bolted to the cylinder frame;
A plurality of cylinders each having at least one exhaust valve and a scavenging port ; one or more fuel injectors per cylinder; and a high-pressure fluid source for supplying a high-pressure fluid capable of storing potential energy by being compressed And at least one electronically controlled hydraulic valve;
A crosshead type large uniflow two-cycle diesel engine configured to be driven mainly by the stored potential energy and controlled by the electronically controlled hydraulic valve. And
At least one camshaft that is mounted in the camshaft housing and is mounted with a plurality of cams each operating the corresponding exhaust valve;
A plurality of hydraulic piston pumps each driven by a corresponding cam on the camshaft;
For each exhaust valve, a hydraulic actuator for moving the exhaust valve in the opening direction, a hydraulic conduit for connecting the hydraulic piston pump to the hydraulic actuator, and for biasing the exhaust valve in the closing direction An elastic member;
A supply conduit extending along the length of the engine and capable of containing a predetermined amount of the high pressure fluid;
Have a, the supply conduit is disposed in the camshaft housing together with the cam shaft, the engine.   The engine according to claim 1, wherein the high-pressure fluid is a medium different from fuel and is separated from the fuel.   The high pressure fluid and the fuel are separated by a piston device provided at least one for each cylinder, and the high pressure fluid moves the piston device during the fuel injection, and then the piston device The engine according to claim 2, wherein the fuel is moved to the combustion chamber in a cylinder.   The engine according to claim 3, wherein the piston device is a pressure intensifier, and the piston device includes a piston having an effective area for the high-pressure fluid that is hydraulic hydraulic fluid that is larger than an effective area for the fuel.   The supply conduit includes a plurality of compression chambers distributed along a longitudinal direction of the engine, and the compression chambers can contain an amount of the hydraulic fluid that can be compressed to accumulate desired potential energy. The engine of claim 4, having a volume of only.   The engine according to claim 5, wherein one compression chamber is provided to supply the hydraulic fluid to a pair of adjacent cylinders.   The engine of claim 6, wherein the compression chamber is at least partially disposed within the camshaft housing.   The engine according to claim 7, wherein the compression chamber shares at least a part of a wall with the camshaft housing.   The engine according to any one of claims 5 to 8, wherein the compression chamber is formed by processing a cavity in a solid metal block.   10. An engine according to any preceding claim, wherein the fluid source of high pressure fluid comprises one or more electric high pressure pumps.   The engine according to any one of claims 1 to 10, wherein one hydraulic valve controls fuel injection to two or more engine cylinders.   The engine according to claim 1, wherein the high-pressure fluid that is a hydraulic fluid is a fuel.   The engine according to claim 12, wherein the predetermined amount of high-pressure hydraulic fluid is accommodated in a common rail.   The engine according to claim 1, wherein the hydraulic valve is a proportional valve.   15. An engine according to any preceding claim, wherein the hydraulic valve is controlled by one or more computers. The engine of claim 15, wherein the one or more computers are configured to adapt at least one of timing and rate adjustment of the fuel injection to an operating state of the engine.   The engine of claim 16, wherein the one or more computers are configured to advance the timing of the fuel injection when the engine load is decreasing.   The engine according to claim 15 or 16, wherein the rate of fuel injection is adjustable during the fuel injection to obtain a desired injection profile.   The engine of any of claims 15 to 18, further comprising a cylinder lubrication system controlled by the one or more computers.   The engine of claim 19, wherein the high pressure fluid provides the cylinder lubrication system power.   The hydraulic pressure that connects the hydraulic piston pump to the hydraulic actuator so that the exhaust valve can start its return process before the return process timing defined by the corresponding cam on the camshaft. 21. An engine according to any preceding claim, wherein the conduit is configured to be depressurized by electronic control valve means.   The hydraulic conduit connecting the hydraulic piston pump to the hydraulic actuator is selectively selected by electronic valve means to delay the return process from the return process timing defined by the corresponding cam on the camshaft. The engine according to any one of claims 1 to 21, wherein the engine is configured to be shut off.   23. An engine according to claim 21 or 22, wherein the engine is configured to control one or more computers to advance or delay the timing of closing of the exhaust valve in relation to operating conditions of the engine.   The camshaft is provided with a mechanism for adjusting an angular position of the crankshaft with respect to an angular position of the crankshaft, and the mechanism is controlled by the computer to change timing of opening and closing of the exhaust valve. Item 24. The engine according to Item 23.

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