Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63H—MARINE PROPULSION OR STEERING
  • B63H21/00—Use of propulsion power plant or units on vessels
  • B63H21/12—Use of propulsion power plant or units on vessels the vessels being motor-driven
  • B63H21/14—Use of propulsion power plant or units on vessels the vessels being motor-driven relating to internal-combustion engines
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B71/00—Designing vessels; Predicting their performance
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D29/00—Controlling engines, such controlling being peculiar to the devices driven thereby, the devices being other than parts or accessories essential to engine operation, e.g. controlling of engines by signals external thereto
  • F02D29/02—Controlling engines, such controlling being peculiar to the devices driven thereby, the devices being other than parts or accessories essential to engine operation, e.g. controlling of engines by signals external thereto peculiar to engines driving vehicles; peculiar to engines driving variable pitch propellers
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/24—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means
  • F02D41/2406—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using essentially read only memories
  • F02D41/2425—Particular ways of programming the data
  • F02D41/2429—Methods of calibrating or learning
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
  • F02B2700/00—Measures relating to the combustion process without indication of the kind of fuel or with more than one fuel
  • F02B2700/03—Two stroke engines
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
  • F02B61/00—Adaptations of engines for driving vehicles or for driving propellers; Combinations of engines with gearing
  • F02B61/04—Adaptations of engines for driving vehicles or for driving propellers; Combinations of engines with gearing for driving propellers

Definitions

• the present invention relates to a method for determining operational parameters of an internal - combustion engine by use of an engine power versus engine speed layout diagram providing an engine design layout area bordered by maximum and minimum engine speed lines and maximum and minimum engine power lines extending between said maximum an minimum engine speed lines.
• an engine layout diagram as defined above providing a layout area, within which there is full freedom for selection of an engine design point offering optimum conditions for the performance and operating profile of the ship.
• a typical prior art example of such a layout diagram is shown in Fig. 1.
• One type of layout diagram conventionally applied has the shape of a parallelogram bordered by maximum and minimum power lines Li - L 3 and L 2 - L 4 corresponding to two constant mean effective pressure (MEP) values and by maximum and minimum speed lines Li - L 2 and L 3 - L 4 .
• the point i refers to the engines nominal maximum continuous rating and within the layout area provided by the diagram there is full freedom to select a so-called specified MCR point for propulsion, shown in the diagram as point M.
• the MCR point must be inside the diagram, as otherwise the propeller speed will have to be changed or a different main engine type chosen. In special cases, however point M may be located to the right of the maximum speed line Li - L 2 . Deviations from this specific type of diagram may be applied, however, e.g. by extension of the low power - high speed region of the diagram to allow decreasing MEP for increasing speed, whereby the minimum power line will show a smaller inclination or even extend in parallel to the speed axis, as has become known in the art.
• Another important engine design point is the so-called optimising point O representing the rating, at which the engine's turbocharger is matched and the engine timing and compression ratio are adjusted.
• the optimising point O is placed on the engine's propeller curve 1 and typically the optimised power at this point will be from 85 to 100 % of the power at point M, when turbocharger and engine timing is taken into consideration. Whereas the specified MCR point M may in special cases be placed outside the diagram by exceeding the line Li - L 2 , the optimising point O must always be placed inside the diagram. For some engine types, which cannot be optimised at part-load the optimising point O will coincide with the MCR point M.
• the power and speed limits for continuous and overload operation of an installed engine having an optimising point O and a specified MCR point M conforming to the ship's specification can be defined by means of a load diagram as shown in Fig. 2.
• the point A which is the maximum 100 % speed and power reference point, is defined as the point on the propeller line 1 through the optimising point O having the specified power of the MCR point M, Normally the point A will coincide with point M, but as mentioned the point M may in special cases, e.g. by installation of a main engine shaft generator, be displaced to the right of the point A along a power line 7 representing the maximum power for continuous operation.
• the continuous engine service range is limited by the line 3 representing the maximum speed acceptable for continuous operation. Provided torsional vibration conditions permit, this limit may be extended to 105 % or even 107 % of the nominal maximum engine speed represented by line L x - L 2 in the layout diagram.
• operational parameters of the main en- gine are determined to allow continuous operation without time limitation within the area limited by the lines 4, 5, 7 and 3 of the load diagram, whereas the area between the lines 1 and 4 is available for operation in shallow water, heavy weather and during acceleration, i.e. for non-steady operation without any actual time limitation.
• the ship's hull and propeller will become fouled, resulting in heavier running of the propeller, i.e. the propeller curve 6 will move to the left from the line 6 towards the line 2 and extra power will be required for propulsion to maintain the ship speed.
• the layout diagram in Fig. 1 is a typical exam- pie of the use of the conventional parallelogram layout for an engine operating a fixed pitch propeller and without a shaft generator driven by the main engine.
• the optimising point O the choice of which has a significant influence, will normally be selected on the engine curve 2 for fouled hull as shown in Fig. 1.
• Point A is then found at the intersection between the propeller curve 1, 2 and the constant power line 7 through the point M. In the illustrated specific case the point A will coincide with the point M.
• the corresponding load diagram can be drawn as shown in Fig.
• the method according to the invention is characterized by the use of an engine layout diagram providing a modified maximum engine power line allowing increasing mean effective combustion pressure and increasing maximum combustion pressure for increasing engine speed, while maintaining maximum resulting force acting on dynamically loaded engine components at a constant level for varying engine speed between said maximum and minimum speed lines.
• the invention is based on the recognition that compared to the conventional use of layout and load diagrams as explained above an unexploited potential is available for increase of the mean effective combustion pressure and the maximum combustion pressure with increasing engine speed, as the increased gas force acting on the piston as a result of pressure increase in the combustion chamber will be counteracted by an increase of inertia force from the reciprocating masses of the dynamically loaded engine parts at increasing engine speed, thus allowing a pressure increase while keeping the maximum resulting force acting on the dynamically loaded engine components at a constant level.
• Figs. 1 to 3 show examples of conventional layout and load diagrams as us for parameter determination and design of marine diesel engines as explained above ; Fig.
• FIG. 4 is a cylinder cross-sectional view of an example of a marine diesel engine illustrating forces acting on dynamically loaded engine components
• Figs. 5 and 6 are graphic representations of the variation of gas force, inertia force and result- ing force on moving engine components as a function of crank angle during a combustion cycle for a cylinder in an engine as shown in Fig. 4, at the low and high speed regions of a layout diagram as shown in Fig. 1
• Fig. 7 shows an example of a modified layout diagram as used in the method according to the invention
• Fig. 8 is a graphic representation corresponding to the representation in Fig. 6 of the variation of gas, inertia and resulting forces at the higher speed end of the layout diagram shown in Fig. 7 ;
• Figs. 5 and 6 are graphic representations of the variation of gas force, inertia force and result- ing force on moving engine components as a function of crank angle during a combustion cycle for a cylinder in an engine as shown in Fig. 4,
• An internal combustion engine designed in accordance with the method of the present invention would preferably be a two-stroke or four-stroke crosshead multi-cylinder marine diesel engine used as a main engine for propulsion of a ship.
• the engine is connected with a propeller via a propeller shafting system, which can include at least a propeller shaft and possibly one or more intermediate shafts and pos- sibly a gearing.
• the engine can typically have a cylinder bore in the range from 25 cm to 130 cm and a maximum engine speed in the range from 50 rpm to 300 rpm.
• the power developed by engines of this type can range from 1500 kW for small bore engines with four cylinders to above 120.000 kW for large bore engines with 12 or more cylinders.
• the engine can e.g. have mean effective combustion pressures in the range from 14 bar to 20 bar, typically from 14.5 bar to 19 bar and can e.g. have maximum combustion pressures in the range from 120 bar to 190 bar.
• each cylinder of the engine as illustrated by the cylinder cross-sectional view in Fig.
• ignition of the fuel-air mixture supplied to the combustion chamber 8 is typically timed to be effected slightly before or shortly after the passage of the piston 9 through its top dead center, normally referred to as TDC, and produces on the piston a combustion gas pressure force Fg as illustrated by a downwards directed arrow.
• TDC top dead center
• Fg combustion gas pressure force
• the reciprocating and rotating engine parts produces an inertia force Fi, as illustrated by an upwards directed arrow, for the return stroke of the reciprocating and rotating engine components 9 to 13 after passage of the piston through its bottom dead center, normally referred to as BDC, the inertia force Fi increasing with increasing rotational engine speed n measured in rpm.
• BDC bottom dead center
• FIGS. 5 and 6 are graphic representations of the variation of the forces Fg, Fi and Fr through a complete cylinder cycle as measured by variation of the crank angle position V from 0° corresponding to the TDC position through the BDC position and back to the TDC position at 360° for engine speeds correspond- ing to the minimum speed at L 3 and the maximum speed at Li, respectively, in the layout and load diagrams in Figs . 1 and 3.
• combustion gas pressure Fg decreases during the combustion stroke from its maximum at the ignition point towards its minimum at the BDC position of the piston 9 corresponding to the maximum volume of the combustion chamber 8, whereas the variation of the inertia force Fi is inverted with respect to that of the gas force Fg, such that minimum and maximum of the inertia force Fi will occur in crankshaft angle positions corresponding sub- stantially to the maximum and minimum values of the combustion gas pressure Fg.
• the inertia force Fi will act in opposite direction with respect to the combustion gas force Fg during a part of the cylinder cycle substantially between the 270° and 90° crankshaft angle positions on either side of the TDC position, whereas in the remaining part of the cycle between the 90° and 270° positions on either side of the BDC position it will act in the same direction as the gas force Fg.
• the resulting force Fr acting on dynamically loaded engine components will show a variation similar to the variation of combustion gas pressure, but with a lower maximum value and a higher minimum value due to contribution from the inertia force Fi .
• Fig. 5 the representation in Fig. 5
• the maximum of the Fi curve for the inertia force, for minimum speed and maximum power operation will represent the maximum force Fmax, to which the dynamically loaded engine compo- nents are exposed and this force is for that reason a decisive critical parameter used in the design and dimensioning of these engine parts, such as the crosshead, the connecting rod and the crankshaft with its bearings.
• Fmax the maximum force used in the design and dimensioning of these engine parts, such as the crosshead, the connecting rod and the crankshaft with its bearings.
• the inertia force Fi will as mentioned above increase with increasing speed.
• the Fg curve shown in Fig, 6 for maximum speed and maximum power operation in point Li of the layout diagram is identical with the Fg curve in Fig. 5 for minimum speed and maximum power operation, the maximum on the Fr curve in Fig.
• the increase of the maximum power at the Li point should preferably and ultimately be chosen such as to lift the maximum on the Fr curve for maximum speed and maximum power operation to the level of the Fmax value applying to minimum speed and maximum power operation in the 3 point of the layout diagram or as close as possible below that level .
• the general configuration of the layout diagram will change from the parallelogram shape as shown in Fig. 1 and indicated by a dashed line in Fig. 7 into a trapez shape.
• FIG. 9 the effect of the modification of the layout dia- gram on the mean effective pressure MEP, the maximum pressure P max , the maximum resulting force Fr max on dynamically loaded engine components and the specific fuel oil consumption SFOC are illustrated at b) , c) , d) and e) , respectively.
• the representations in Fig. 9 apply to the use of the conventional parallelogram shaped layout diagram in Fig. 1, by which MEP and P max are kept constant between the minimum and maximum speed points L 3 and L 1# whereas Fr max decreases, as also illustrated by the representations in Figs. 5 and 6, and SFOC is kept constant.
• Fig. 9 the effect of the modification of the layout dia- gram on the mean effective pressure MEP, the maximum pressure P max , the maximum resulting force Fr max on dynamically loaded engine components and the specific fuel oil consumption SFOC are illustrated at b) , c) , d) and e) , respectively.
• the representations in Fig. 9 apply to the use of the
• the modification of the layout diagram provided by the method according to the invention will increase MEP and P max from the L 3 to the Li point, whereas Fr as well as SFOC will re- main constant.
• the increase of MEP and P max from the minimum speed at L 3 to the maximum speed at Li will depend on the actual engine type, e.g. with respect to number of cylinders, engine design for fixed pitch or controllable pitch operation, operation of s shaft generator by the main drive shaft etc.
• the increase of MEP and P max may typically be such that MEP at point Li will be 103 to 107 % of MEP at point L 3 , whereas P max at point I» ⁇ will be 107 to 109 % of P raax at point L 3 .
• Fig. 11 a further modification of a layout diagram is shown, by which the modified maximum power line L ⁇ -L 3 shows a stepwise variation to allow in- crease of mean effective combustion pressure MEP and increasing maximum combustion pressure P max in a number of steps between minimum and maximum engine speed, while keeping MEP and P max at a substantially constant level in each step.
• a modified maximum power line L ⁇ -L 3 may show a curved variation.
• amore versatile and flexible use of the modified layout diagram may be pro- vided for practical applications.
• the method of the invention will permit design and dimensioning of dynamically loaded engine parts by use of conventional design parameters and criteria, including a F max value obtained from a rep- resentation as shown in Fig. 5, there may be a need to compensate for the increase of MEP and P max at maximum speed operation by modifying the cylinder design to take account of the increased pressure load in the combustion chamber, e.g. by appropriate rein- forcement of the cylinder top cap and the connecting members, usually stay bolts, by which it is connected with the main engine block.
• the meritorious effects of the method of the invention are that while maintaining conventional critical design and dimensioning criteria for dynamically loaded engine components like crossheads, connecting rod and crank shaft, operational parameters may be determined and selected to allow increased mean effective pressure MEP and maxi- mum pressure P max and thereby obtain an increased power output for continuous high speed operation without significantly affecting specific fuel oil consumption.
• the additional power potential offered by the invention may be implemented by appropriate control of operational parameters of the combustion process, such as ignition point and operation points for suc- tion and exhaust valves during each cylinder cycle by means known in the art .
• the method according to the invention is not limited to the specific forms of a layout diagram shown in figs. 7 and 11.
• the maximum and minimum power lines L x -L 3 and L 2 - 4 need not be linear in a mathematical sense, but may as illustrated and mentioned above show a discontinuous such as a stepwise or a curved variation.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• Ocean & Marine Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Control Of Vehicle Engines Or Engines For Specific Uses (AREA)
• Supercharger (AREA)
• Combined Controls Of Internal Combustion Engines (AREA)
• Output Control And Ontrol Of Special Type Engine (AREA)

Priority Applications (4)

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• 2004
  • 2004-04-23 WO PCT/DK2004/000281 patent/WO2005103463A1/en active Application Filing
  • 2004-04-23 JP JP2006515702A patent/JP4195060B2/ja not_active Expired - Fee Related
  • 2004-04-23 CN CNB2004800011072A patent/CN100378309C/zh not_active Expired - Fee Related
  • 2004-04-23 CH CH00656/05A patent/CH698949B1/de not_active IP Right Cessation

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