Classifications

• • 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
  • F02D41/009—Electrical control of supply of combustible mixture or its constituents using means for generating position or synchronisation signals
• • 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
  • 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
  • F02D41/2451—Methods of calibrating or learning characterised by what is learned or calibrated
  • F02D41/2474—Characteristics of sensors
• • 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
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/04—Introducing corrections for particular operating conditions
  • F02D41/042—Introducing corrections for particular operating conditions for stopping the engine
• • 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
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/14—Introducing closed-loop corrections
  • F02D41/1497—With detection of the mechanical response of the engine

Definitions

• the present invention relates to method of determining an offset relating to crank angle measurement in connection with a cylinder of an internal combustion piston engine.
• Invention relates also to control system for determining an offset relating to crank angle measurement in connection with a cylinder of an internal combustion piston engine.
• IMEP mean effective pressure
• a controller for controlling the combustion of an internal combustion engine.
• the controller controls the combustion on the basis of certain drive control parameters, such as the ignition timing and the air-fuel ratio, so as to optimize in terms of the driving performance the values and ranges of fluctuation of certain combustion parameters.
• Combustion parameters which are used to control the combustion process in an internal combustion engine include e.g. maximum combustion pres- sure, crank angle at the time of achieving the maximum combustion pressure, maximum rise rate of the combustion pressure, and indicated mean effective pressure. These combustion parameters are determined by the controller on the basis of the pressure profile in the cylinders of the engine which is detected by a pressure sensor.
• the pressure sensor Since the pressure sensor is directly attached to the engine, it is sub- jected to significant changes in temperature, resulting in a tendency to deteriorate with age. In view of this, as well as its initial instability, the accurate detection of the pressure achieved by the sensor is in practice cumbersome.
• US 4944271 discloses a manner of correcting the pressure measurement by an offset of the pressure sensing means, which is determined by com- paring the pressure in the cylinder, as detected by the pressure sensing means at the time when the crank is at the top dead center position as detected by the crank angle sensor, with the product of the compression ratio of the engine and the manifold pressure as detected by the manifold pressure sensor.
• An additional procedure for compensating the effects of temperature is also disclosed.
• An object of the invention is to provide a method of determining an offset relating to crank angle measurement in connection with a cylinder of an internal combustion piston engine according to the engine in which the performance is considerably improved compared to the prior art solutions.
• an integral value of indicated mean effective pressure in the cylinder is determined over a range of crank angle during the combustion chamber of the cylinder is closed, and wherein a dead center position of the piston is located symmetrically within the range, and
• crank angle position offset value is determined based on the deter- mined integral value of indicated mean effective pressure and the reference value for the indicated mean effective pressure.
• crank angle position offset value makes it possible increase the accuracy of defining the actual IMEP value by means of which it is possible to fur- ther improve the control of combustion process in the internal combustion engine. Particularly it is possible tackle with the differences between the dynamics of the cylinder pressure sensors.
• the step of is refraining from fuel combustion in the cylinder may comprise actively controlling the cease of fuel combustion, or making use of a stage of the engine cycle where no combustion takes place, as will become apparent later in the disclosure,
• the method is used for calibrating the crank angle position measurement such that the crank angle position offset value is used for correction of the crank angle position measurement value.
• the method is used as diagnosing the position offset in the cylinder pressure measurement.
• the dead center position is a top dead center position and during the method it is refrained from bringing fuel into the cylinder and/or initiating the combustion.
• the method may be practised during stopping procedure of the engine while the engine is still rotating due to its inertia. This way no special arrangements are needed.
• the top dead center is advantageously the one during/between the compres- sion and power stokes.
• the combustion chamber of the cylinder is closed in a four stoke engine when all of the gas exchange valves of the cylinder are maintained closed.
• the combustion chamber is the space limited by the side walls of the cylinder, top wall of the cylinder or a cylinder head and the top of the piston.
• the dead center position is a bottom dead center position and all of the intake valves of the cylinder are closed so that during the method all of the gas exchange valves are maintained closed.
• V R volume of the cylinder swept by the piston when the engine is rotated the range of crank angle ⁇ 1 to ⁇ 2
• crank angle range between the start angle and the end angle is symmetrical over the dead center position. This way the offset value is easily determined because the reference value for the indicated mean effective pressure is zero.
• the start angle of the range is less than or equal to 180 degrees before the top dead center and the end angle of the range is less than or equal to 180 degrees after the top dead center.
• the start angle of the range is less than or equal to 100 degrees before the top dead center and the end angle of the range is less than or equal to 100 degrees after the top dead center.
• start angle of the range is less than or equal to 100 degrees before the bottom dead center and the end angle of the range is less than or equal to 100 degrees after the bottom dead center.
• the bottom dead center is advantageously the one during/between the intake and compression stokes.
• Figure 1 illustrates a control system in an internal combustion piston engine according to an embodiment of the invention
• FIG. 2 illustrates a control system in an internal combustion piston engine according to another embodiment of the invention
• FIG. 3 illustrates an example of operation of the invention
• Figure 4 illustrates another example of operation of the invention.
• Figures 1 and 2 depict schematically a control system according to an embodiment of the invention adapted in connection with an internal combustion piston engine 10.
• the engine 10 is depicted in extremely simplified manner referring to only one of the cylinders of the engine.
• the present invention provides a method of and a control system for determining a offset relating to crank an- gle measurement in connection with a combustion control system of the engine, which can be used for providing more accurate control of the engine.
• the main components of the engine are one or more cylinders 12 and a piston 14 arranged to reciprocate in the cylinder 12.
• the gas exchange in the cylinder 12 is controlled by gas exchange valves 22, 24, comprising at least one intake valve 24 and at least one exhaust valve 22.
• Each of the pistons 14 is connected to a crank shaft 16 by a connecting rod 18.
• the mechanical dimensioning of parts defines geometry of the combustion chamber 20 and also the volume swept by the piston when moving be- tween its top dead center and bottom dead center.
• the control system 1 1 for determining an offset relating to crank angle measurement in connection with a combustion control system of the engine 10 comprises a cylinder pressure sensor 26 adapted to measure the pressure in the combustion chamber 20 of the cylinder 12 and to provide a pressure signal. There is also a crank shaft position sensor i.e. crank angle sensor 28 provided in the control system to provide a signal indicative to the position of the crank shaft 16.
• the control system is further provided with a cylinder volume determination unit 30, which is adapted to receive the signal indicative to the position of the crank shaft 16 from the crank angle sensor 28.
• the cylinder volume determination unit 30 comprises executable instructions to convert the position signal into respective cylinder volume. That may be based on a predetermined lookup table or a function for numerical calculation belonging to the instructions.
• the cylinder volume determination unit 30 is adapted to provide a signal indicative to the volume of the cylinder at respective crank angle.
• the control system 1 1 comprises also an indicated mean effective pres- sure (IMEP) determination unit 32, which is in the following called as IMEP-unit 32.
• the IMEP-unit 32 is connected to the cylinder pressure sensor 26 and adapted to receive the pressure signal from the cylinder pressure sensor 26.
• the IMEP-unit 32 is also connected to the cylinder volume determination unit 30 and adapted to receive the signal indicative to the volume of the cylinder.
• the IMEP-unit 32 is further connected to the crank angle sensor 28 and adapted to receive the signal indicative to the position of the crank shaft 16 from the crank angle sensor 28.
• the IMEP-unit 32 is provided with executable instructions to determine an integral value of indicated mean effective pressure in the cylinder 12. Particularly the instructions comprises instructions to deter- mine the integral value of indicated mean effective pressure by using a formula wherein
• V R volume of the cylinder swept by the piston when the engine is rotated over the range of crank angle ⁇ 1 to ⁇ 2, obtainable from the cylinder volume determination unit 30
• the control system is further provided with a controller unit 36 and a set point unit 34.
• the set point unit 34 is adapted to provide a reference value for the controller unit 36.
• the controller unit 36 connected to the set point unit 34 and to the IMEP-unit 32.
• the controller unit 36 is adapted to receive the integral value of indicated mean effective pressure from the IMEP-unit 32 and a reference value provided by the set point unit 34.
• the controller unit 36 is provided with executable instructions to provide a crank angle position offset value as its output 38.
• the reference value provided by set point unit represents the target integral value of indicated mean effective pressure for a given crank angle range and the integral value of indicated mean effective pressure from the IMEP-unit 32 represents a feedback value from the engine.
• Figure 1 refers to a control system 1 1 for determining an offset relating to crank angle range within which the piston is passing by the top dead center position.
• the control system is provided instructions to disable the fuel admission to the cylinder 12 during the determination of the offset.
• the IMEP-unit 32 is adapted to provide an output signal, which is depicted by line 33 extending from the IMEP-unit to a fuel injector 23, based on which the combustion control system (not shown) of the engine misses out the fuel admission into and/or ignition in the combustion chamber. This may be accomplished by controlling the fuel injector 23 not to inject any fuel during the cycle in question.
• the method is refrained from bringing fuel into the cylinder and/or initiating the combustion.
• Figure 2 refers to a control system 1 1 for determining an offset relating to crank angle range where the piston is passing by the bottom dead center.
• the control system in order to make use of the control system when the piston is passing the bottom dead center, the control system is provided with instructions to close the intake valve 24 and maintain the valve 24 closed during the determination of the offset. Now the cylinder 12 is in the stage of intake - compression stroke and therefore the exhaust valve(s) 22 are closed in any case based on the normal control of the gas exchange valves.
• the IMEP-unit 32 is adapted to provide an output signal, which is depicted by line 33' extending between the IMEP-unit 32 and the intake valve 24 control system, based on which the combustion control system (not shown) of the engine controls the intake valve 24 to close while the method is practised.
• the determination of the offset is performed during the intake valve 24 and the exhaust valve 22 i.e. all the gas exchange valve are simultaneously closed and no combustion takes place and/or combustion of fuel is disabled during the method.
• the control system in order to make use of the control system when the piston is passing the bottom dead center, the control system is provided with instructions to perform the determination of the offset during the intake valve 24 and the exhaust valve 22 are simultane- ously closed. Since the cylinder 12 is in the stage of intake - compression stroke, the exhaust valve(s) 22 are closed in any case based on the normal control of the gas exchange valves. In this embodiment the intake valve 24 is closed early before the bottom dead center for other reasons, and the information that the valve(s) is closed is transmitted to the IMEP-unit 32 via a com- munication line 33' and is used as signal allowing the initiation of determination of the offset value.
• the control system operates as is disclosed in the following explaining the method of determining an offset relating to crank angle measurement in connection with a cylinder of an internal combustion piston engine.
• the following steps are involved. Firstly, it is essential that the engine rotates or is made to rotate at least over a predetermined crank angle range and at least the cylinder in connection with which the method is practised such that is refrained from fuel combustion during the practising of the method.
• a reference value for the indicated mean effective pressure is determined by the set point unit 34.
• An integral value of indicated mean effective pressure in the cylinder is determined over a range of crank angle, during which the combustion chamber is closed i.e. all of the gas exchange valves of the cylinder are maintained closed, wherein a dead center position of the piston is located with the range, and the crank angle position offset value is determined based on the determined integral value of indicated mean effective pressure and the reference value for the indicated mean effective pressure.
• FIG. 3 shows a chart where the horizontal axis depict the crank angle (CA) in degrees and the vertical axis represents normalized value of the variables, which are the derivative of the cylinder volume 42 and three different situations of measured pressure in 40.1 ,40.2,40.3 the cylinder while it is refrained from fuel combustion during the practising of the method.
• the engine is so called motored.
• the start angle ⁇ 1 of the range is 180 degrees before the top dead center and the end angle ⁇ 2 of the range is 180 degrees after the top dead center.
• the used range may be varied as long as the combustion chamber is closed by the gas exchange valves. However, if the range is too narrow the sensitivity of the calculations to disturbances is increased.
• the integral value of indicated mean effective pressure is determined by the formula above. [0037] The method is practised when the crank angle range is symmetrical over the dead center position. In this case the start crank angle is as much before the dead center position as the end crank angle is after the dead center position, and the reference value is zero. Thus, the deviation of the integral value of indicated mean effective pressure from zero reveals the offset status.
• the formula can be interpreted as a sum of products of cylinder pressure and deriv- ative of the cylinder volume, and it can be seen that zero IMEP may only be achieved when the pressure 40.1 and volume are in the same phase. A phase shift making the pressure shift to the left 40.2 will imply a negative IMEP and vice versa 40.3.
• the range may also be selected differently. For example when the range is around the top dead center the range may be substantially wide due to the valve timings of a four stroke engine during compression and power stroke phases, while motoring the engine. It has been found that for adequately accu- rate calculation the start angle ⁇ 1 is at least 100 degrees before the top dead center and the end angle ⁇ 2 of the range is at least 100 degrees after the top dead center.
• FIG. 4 shows a chart similar to that in Figure 3 but here the angle range is around the the bottom dead center of a cylinder during intake- compression stages in four stroke engine.
• the horizontal axis depict the crank angle (CA) in degrees and the vertical axis represents normalized value of the variables, which are the derivative of the cylinder volume 42 and three different situations of measured pressure in the cylinder 40.1 ,40.2,40.3.
• the method is practised when the crank angle range is symmetrical over the dead center position.
• the start crank angle is as much before the dead center position as the end crank angle is after the dead center position, and the reference value is zero.
• the deviation of the integral value of indicated mean effective pressure from zero reveals the offset status.
• the formula can be interpreted as a sum of products of cylinder pressure and derivative of the cylinder volume, and it can be seen that zero IMEP may only be achieved when the pressure 40.1 and volume are in the same phase. A phase shift making the pressure shift to the left 40.2 will imply a negative IMEP and vice versa 40.3.
• the range may also be selected differently. For example when the range is around the bottom dead center the usable range is mostly restricted by the required time the intake valve needs to open during the intake stroke. It is however possible to close the intake valve well before the bottom dead center, particularly when the engine is supercharged, in which case the elevated charge pressure compensates the shorter intake valve opening time i.e. the earlier closing timing. It has been found that for adequately accurate calculation the start angle ⁇ 1 is at least 100 degrees before the bottom dead center and the end angle ⁇ 2 of the range is at least 100 degrees after the top dead center. It should be noted that the used range in this embodiment may be varied as long as the combustion chamber is closed by the gas exchange valves. However, the intake valve should be opened as early as practically possible since if the range is too narrow to avoid extensively increase sensitivity of the calculations to disturbances.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Analytical Chemistry (AREA)
• Combined Controls Of Internal Combustion Engines (AREA)

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Citations (7)

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• 2015
  • 2015-09-11 KR KR1020187005300A patent/KR102021249B1/ko active IP Right Grant
  • 2015-09-11 CN CN201580082898.4A patent/CN107949692B/zh active Active
  • 2015-09-11 WO PCT/FI2015/050597 patent/WO2017042423A1/en unknown
  • 2015-09-11 EP EP15788450.3A patent/EP3320200B1/en active Active

Patent Citations (7)

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