Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02N—STARTING OF COMBUSTION ENGINES; STARTING AIDS FOR SUCH ENGINES, NOT OTHERWISE PROVIDED FOR
  • F02N9/00—Starting of engines by supplying auxiliary pressure fluid to their working chambers
  • F02N9/04—Starting of engines by supplying auxiliary pressure fluid to their working chambers the pressure fluid being generated otherwise, e.g. by compressing air
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D35/00—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D35/00—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
  • F02D35/02—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions
  • F02D35/023—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions by determining the cylinder pressure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02N—STARTING OF COMBUSTION ENGINES; STARTING AIDS FOR SUCH ENGINES, NOT OTHERWISE PROVIDED FOR
  • F02N2200/00—Parameters used for control of starting apparatus
  • F02N2200/02—Parameters used for control of starting apparatus said parameters being related to the engine
  • F02N2200/021—Engine crank angle

Definitions

• the present invention relates to a method for determining the crank angle of a multicyl- inder internal combustion engine, as defined in the preamble of claim 1.
• the invention also concerns an arrangement for determining the crank angle of a multicylinder internal combustion engine in accordance with the preamble of the other independent claim.
• crank angle of the engine must be determined.
• Engines are often equipped with crank angle sensors that can be used for instance for determining correct fuel injection timing. These sensors are usually incremental encoders, which determine the crank angle on the basis of detection of a reference mark and angular changes of the crankshaft. This means that the crank angle cannot be determined when the engine is at rest.
• One method for determining the crank angle is to rotate the engine before start so that a reference mark passes the crank angle sensor and the absolute crank angle is thus known. Then the engine has to be rotated further into a starting position.
• a drawback of this method is that the method is time consuming and a lot of energy is needed.
• Patent application US 2007005222 Al discloses an air start-up system for an internal combustion engine.
• the system comprises solenoid-controlled starting valves in connection with each cylinder of the engine for introducing starting air into the cylinders.
• An absolute rotary encoder is used to detect the angular position and rotational speed of the engine for determining the correct timing and duration of starting air injection.
• a problem with absolute rotary encoders is that they are fragile and not intended for extended periods of rotation at high speed. Therefore, the lifetime of an absolute rotary encoder is often very limited.
• the object of the present invention is to provide an improved method for determining the absolute crank angle of a multicylinder internal combustion engine. Another object of the invention is to provide an improved arrangement for determining the absolute crank angle of a multicylinder internal combustion engine.
• the method for determining the crank angle of a multicylinder internal combustion engine when the engine is at rest comprises the steps of introducing a predetermined amount of pressure medium into at least two of the cyl- inders of the engine, measuring pressure in the cylinders into which the pressure medium has been introduced, and calculating the crank angle of the engine on the basis of the pressure measurements.
• the present invention enables determination of the crank angle of an internal combus- tion engine when the engine is at rest without the use of absolute rotary encoders that fail easily. Neither is it necessary to rotate the crankshaft for determining the crank an- gle.
• the method can be used to reliably determine the crank angle before starting the engine and the consumption of the starting air is thus minimized.
• the pressure medium is introduced into the cylinders from a starting air receiver.
• starting air is used to determine the crank angle, no separate pressure medium source is needed.
• the amount of the pressure medium introduced into the cylinders is controlled by starting valves.
• starting valves are used to control the amount of pressure medium that is introduced into the cylinders, no additional flow regulation devices are needed.
• the crank angle is calculated in a control unit.
• the arrangement for determining the crank angle of a multicylinder internal combustion engine when the engine is at rest comprises a pressure medium source, means for connecting the pressure medium source to at least two of the cylinders of the engine for introducing a predetermined amount of pressure medium into the cylinders, means for controlling the admission of the pressure medium into the cylinders, means for measuring pressure in the cylinders into which the pressure medium is introduced, and means for calculating the crank angle of the engine on the basis of the pressure measurements.
• Fig. 1 shows schematically a simplified illustration of an internal combustion with a starting system and an arrangement for determining the crank angle. Detailed description of the invention
• Fig. 1 is shown an internal combustion engine 1.
• the engine 1 is a large four-stroke internal combustion engine that could be used for instance in a power plant or as the main or auxiliary engine of a ship.
• the engine 1 comprises four cylinders 4 that are arranged inline.
• the engine 1 could comprise any reasonable number of cylinders 4.
• the cylinders 4 can be arranged inline, in a V-configuration or some other configuration.
• the engine 1 can be either a spark- ignition engine or a compression ignition engine.
• the engine 1 is provided with an air receiver 2 for storing pressurized starting air.
• the air receiver 2 is connected with a starting air duct 3 to the cylinders 4 of the engine 1.
• Each branch of the starting air duct 3 is provided with a starting valve 5 for controlling the admission of the starting air into the cylinders 4.
• the operation of the starting valves 5 is controlled by a control unit 7.
• the starting valves 5 can be actuated by any conventional means well-known in the art. For instance electrical, hydraulic or pneumatic actuators can be used. It is also possible to utilize control valves that control the starting valves 5. For instance solenoids can be used to actuate the control valves. In the embodiment of Fig. 1 , all the cylinders 4 of the engine 1 are connected to the air receiver 2 and equipped with a starting valve 5. However, it is possible that only some of the cylinders 4 are connected to the air receiver 2.
• the engine 1 is started by opening the starting valves 5 in a suitable order and introducing thus pressurized starting air into the cylinders 4.
• the starting air moves the pistons inside the cylinders 4 and rotates the crankshaft 8.
• Air injection is continued for reaching an adequate starting speed and fuel is injected into the cylinders 4 with appropriate timing so that the engine 1 eventually starts.
• the rotational position and speed of the engine 1 can be determined from the flywheel 9 that is attached to the end of the crankshaft 8.
• the engine 1 is provided with a crank angle sensor 10 for that purpose.
• each cylinder 4 of the engine is equipped with a pressure sensor 6.
• the engine 1 comprises a large number of cylinders 4, it is not necessary to provide all the cylinders 4 with pressure sensors 6.
• At least two starting valves 5 are opened for a predetermined period of time for introducing pressurized starting air into the respective cylinders 4.
• the duration of the period of time is chosen so that the pressure inside the cylinders 4 increases, but remains low enough for not moving the piston.
• the pressure of the air receiver 2 is kept constant, and the amount of air that flows into the cylinders 4 can thus be determined.
• the pressure in the cylinders 4 is simultaneously monitored by means of the pressure sensor 6. Based on the measured pressure, the control unit 7 calculates the position of the piston in the cylinder 4. The position of the piston can be used to calculate the crank angle of the engine 1.
• the gas exchange valves of that cylinder 4 must be closed. If the exhaust valves or intake valves of the cylinder 4 are open, the starting air introduced into the cylinder 4 can escape through the valve openings and the pressure inside the cylinder 4 does not increase. If the starting air is introduced into several cylinders 4 either simultaneously or consecutively, a pressure increase can be measured at least in some of the cylinders 4 and the crank angle can thus be determined.
• Another option would be closing the gas exchange valves in those cylinders 4 into which the starting air is introduced. This is possible if the valves can be actuated without a camshaft and can be controlled independently. This could be the case for instance with hydraulically actuated gas exchange valves. Still another option would be checking in which cylinders 4 the gas exchange valves are closed and to introduce the pressure medium into those cylinders 4.
• the pressure medium used for determining the crank angle does not need to be starting air, but a separate source of pressurized gas may be provided. It is also possible to equip the pressure medium ducts with flow meters so that the amount of the pressure medium introduced into the cylinders can be determined directly.
• the invention can also be applied to a two-stroke engine.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Combined Controls Of Internal Combustion Engines (AREA)
• Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

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Citations (5)

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• 2010
  • 2010-09-08 FI FI20105933A patent/FI20105933A/fi not_active Application Discontinuation
• 2011
  • 2011-07-22 EP EP11770833.9A patent/EP2614248B1/en active Active
  • 2011-07-22 WO PCT/FI2011/050670 patent/WO2012032216A1/en active Application Filing
  • 2011-07-22 CN CN201180043581.1A patent/CN103109074B/zh active Active
  • 2011-07-22 KR KR1020137008860A patent/KR101668149B1/ko active IP Right Grant

Patent Citations (5)

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