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
  • F02D41/30—Controlling fuel injection
  • F02D41/38—Controlling fuel injection of the high pressure type
• • 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
  • F02D41/008—Controlling each cylinder individually
  • F02D41/0085—Balancing of cylinder outputs, e.g. speed, torque or air-fuel ratio
• • 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
  • F02D41/22—Safety or indicating devices for abnormal conditions
  • F02D2041/224—Diagnosis of the fuel system
  • F02D2041/226—Fail safe control for fuel injection pump
• • 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
  • F02D41/008—Controlling each cylinder individually
• • 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
  • F02D41/1498—With detection of the mechanical response of the engine measuring engine roughness

Definitions

• the invention relates to a method for the cylinder-selective control of a multi-cylinder self-igniting four-stroke internal combustion engine with cylinder-selective fuel injection, according to the preamble of claim 1 and a device for carrying out this method.
• An internal combustion engine with self-ignition for example a diesel engine, offers compared to an internal combustion engine with external ignition
• a gasoline engine fewer possibilities to influence the combustion process, so the possibilities of mixture preparation of a gasoline engine are completely eliminated.
• the working principle of the diesel engine only enables the start of injection and the amount of fuel to be influenced.
• Inevitable component differences result in undefined differences in the behavior of the individual cylinders , which lead to impairments in relation to fuel consumption, pollutant emissions, vibration behavior, synchronism, acoustics and operation
• Operating time can be understood as component differences, all deviations of the components of a diesel engine from their theoretical ideal value.
• the component differences can be caused by inevitable manufacturing tolerances as well as caused by abrasion deformation, deposits, etc. during operation of the internal combustion engine
• the differences between those components of a diesel engine that are involved in the fuel supply or in the combustion process are primarily responsible for the impairments caused by the component differences.
• injection nozzles are particularly problematic, where there is a requirement that all injection nozzles of a diesel engine should have the exact same hydraulic flow of fuel.
• a reduced hydraulic flow of fuel in an injection nozzle of the diesel engine during the combustion cycle leads to a reduction in the mean pressure in the corresponding cylinder and thus to rotational irregularities in the crankshaft.
• the medium pressure is a variable into which the combustion chamber pressure curve enters during the combustion cycle of a cylinder, and which can serve as a measure of the energy converted in this cylinder.
• the invention has for its object to provide an experienced for controlling self-igniting four-stroke internal combustion engines of the type mentioned, in which the effect of component differences of the components for the fuel supply and the combustion system are minimized in order to further improve the engine properties, such as fuel consumption, to enable.
• This object is achieved by the features in the characterizing part of patent claim 1. Different parameters depending on the speed are derived from the curve of the instantaneous crankshaft speed, which are correlated as precisely as possible with the respective mean pressure of the combustion chambers of the internal combustion engine, and from which cylinder-selective correction values for the cylinder-selective equality of the mean pressures can be determined Correction values are determined which cause a defined unequal adjustment of the mean pressures of the combustion chambers of the internal combustion engine. For example, a cylinder can be fired more or less to suppress vibrations or resonances on the motor vehicle
• the equalization or defined non-equality of the mean pressures in the combustion chambers of the internal combustion engine is brought about by the cylinder-selective change in the injection timing and the amount of fuel injected into the combustion chambers of the internal combustion engine
• the cylinder-selective changes in the injection quantity and the time of injection of the fuel into the combustion chambers of the internal combustion engine are carried out in such a way that they add up to zero in the sum of the cylinder-selective changes, thereby ensuring that the operating state or operating state desired by the driver the power output of the internal combustion engine is not changed, preferably two types of parameters from the curve shape of the current crankshaft speeds can be used to equate the cylinder-selective mean pressures.
• Speed average values which are formed over a maximum of 720 degrees crankshaft rotation, divided by the number of cylinders, or speed amplitudes
• the speed amplitudes of the curve of the current crankshaft speeds are determined by averaging a number of current crankshaft speeds of the same crankshaft rotation angle of the periodically repeating cycle of the internal combustion engine, usually comprising two crankshaft revolutions
• An advantageous development of the invention consists in the storage of curve profiles of the current crankshaft speeds and / or of cylinder-selective correction values for comparison purposes. The storage can take place after the manufacture of the internal combustion engine, after a repair or at any intervals
• the stored curve profiles of the current crankshaft speeds and / or the cylinder-selective correction values can be used for the early detection of combustion and / or compression problems of the internal combustion engine.
• the result of the early detection can be displayed in the motor vehicle or called up in the course of an inspection in a specialist workshop
• crankshaft rotation angle is detected on the crankshaft by means of a measuring device having a signal transmitter, and the instantaneous crankshaft speeds are determined therefrom by a processing unit.
• the camshaft can be provided with a signaling device which enables the detection of the camshaft turning angle. This provides information on whether a cylinder is in the 1st or 3rd or in the 2nd or 4th working cycle
• crankshaft measuring device and the camshaft measuring device can be monitored.
• the ratio of the signals emitted by the individual signal generators of the two measuring devices must be constant
• a further development provides that in each case a signal transmitter of the measuring device of the crankshaft and the measuring device of the camshaft is used to mark a predetermined angle of rotation of the respective shaft
• signals from signal generators of the crankshaft and the camshaft can be used to check the synchronization between the crankshaft and the camshaft
• the crankshaft rotation angle and the crankshaft speed can alternatively also be determined from the camshaft rotation angle
• the cylinder-selective equalization or defined non-equalization of the medium pressure enables the influence of pollutant emissions, fuel consumption, the vibration behavior, the synchronism behavior, the operating time and / or the acoustics of the internal combustion engine Speed-dependent cross-influences changed to different degrees. It can follow that one parameter more in the lower, the other parameter more in the upper speed range of a diesel engine is correlated with the cylinder-selective medium pressure, which makes it necessary to use the parameter speed-specifically.
• independent fuel supply system each consisting of an injection pump, a line and an injection nozzle, the so-called PLD system, for detecting the crankshaft rotation angle
• the crankshaft is provided with a measuring device and an associated processing unit for determining the instantaneous crankshaft speed for detecting the camshaft rotation angle
• the camshaft is provided with a measuring device for determining the current camshaft speed - ⁇ -
• FIG. 2 shows a representation of the control algorithm for equating the mean pressures
• FIG. 3a shows the cylinder-specific mean pressures of a four-cylinder diesel engine without activated individual cylinder adjustment
• FIG. 3 b shows a representation of the cylinder-specific mean pressures of a four-cylinder diesel engine with activated individual cylinder adjustment
• FIG. 4a shows a typical curve of the current crankshaft speeds over 720 degrees crankshaft rotation angle without activated idle idle control in an eight-cylinder diesel engine
• Figure 4b shows a typical curve of the current crankshaft speeds over 720 degrees crankshaft rotation angle with activated idle idle control in an eight-cylinder diesel engine.
• Equalizing the cylinder-selective mean pressures for the compensation of the component differences requires a separate, independent fuel supply for each cylinder of the diesel engine, which consists of an injection pump, a line and an injection nozzle, the PLD system ("Pump - Line - Nozzle").
• the piston injection pumps driven by the camshaft are connected to the fuel tank on the side of the fuel supply via solenoid valves and to the injection nozzles on the engine side.
• the crankshaft is equipped with a measuring device and a processing unit, the signal transmitter of which consists of an encoder wheel rotating with the crankshaft, which is provided with 36 markings and an additional marking which are scanned by an inductive sensor.
• the additional marking indicates an angular position of the crankshaft known to the control unit, e.g. the top dead center of the 1 cylinder
• the processing unit determines 36 current crankshaft speeds during a crankshaft revolution.
• the control unit thus has information about the crankshaft rotation angle and crankshaft speed available with a resolution of 10 degrees
• the signal transmitter of the camshaft measuring device consists of an encoder wheel rotating with the camshaft, which is provided with 12 markings and an additional marking which are scanned by an inductive sensor.
• the additional marking identifies an angular position of the camshaft known to the control unit.
• the control device can determine the camshaft rotation angle and the camshaft speed with a resolution of 30 degrees (analogous to 60 degrees crankshaft rotation angle).
• the control device can detect an event in which the diesel engine's work cycle, which repeats every two crankshaft revolutions, changes Assign the current crankshaft speed.
• the control unit can assign an increase in the crankshaft speed to the expansion of the 3rd cylinder.
• the two independent measuring devices of the crankshaft and camshaft can be used by the control unit for permanent, mutual function control.
• the ratio of the signals from the crankshaft sensors to the signals from the camshaft sensors must be in the example given here 6 1 From the change in this ratio, the control unit recognizes a malfunction in one of the inductive sensors, whereupon all control processes are deactivated on the basis of these measuring devices until the defect has been remedied and from which the diesel engine can continue to be operated, for example with standard values.
• the control unit uses the 72 current crankshaft speeds over 720 degrees crankshaft rotation angle to determine a curve shape that resembles an absolute sine curve. Such a curve is shown in FIG. 1. This curve shape reflects the differences in the mean pressure in the combustion chambers of the internal combustion engine.
• the task of the control unit is a stable control of the fuel injection to compensate for component differences by equating the cylinder-specific mean pressures.
• the cylinder-specific mean pressures cannot be determined directly, it is necessary to provide a suitable, cylinder-specific, determinable parameter which can serve as input information for the control device for determining control variables.
• This parameter must be characterized in that the differences in the parameters are correlated as well as possible with the differences in the medium pressure.
• the sensitivity of the characteristic variable should be very low, ie if the injection quantity in one of the cylinders changes, the response of the characteristic variable of another cylinder to this change should be very small, even if the cross-sensitivity of a characteristic variable is weak, the diagnostic ability of the control unit is impaired . With strong cross-sensitivities, stable regulation of the medium pressures cannot be achieved.
• the response of the characteristic variable of a cylinder after a variation of the injection process should be linear to the resultant variation in the mean pressure, but at least be in the same direction and monotonous, since otherwise the control unit cannot make a clear diagnosis and would not be able to provide stable control.
• Either average speed values over 720 degrees crankshaft rotation angle divided by the number of cylinders or speed amplitudes can be used to record such a parameter from the curve of the current crankshaft speeds. Due to the long detection interval, average speed values are particularly insensitive to the positioning errors of the crankshaft markings, which gain influence at high crankshaft speeds. With increased sensitivity to positioning errors, speed amplitudes are particularly insensitive to cross influences. Accordingly, speed amplitudes are preferably used as a parameter in the lower speed range and average speed values in the upper speed range.
• Crankshaft speeds of up to approximately 600 revolutions per minute can be regarded as the lower speed range for the use of speed amplitudes.
• speed amplitudes are used as a parameter, for example for cylinder-selective leak tests of the combustion chambers of internal combustion engines.
• speed average values are preferably used as a parameter for the cylinder-selective determination of the correction values.
• the instantaneous crankshaft speeds KD1 belonging to a cylinder are carried out via a low-pass filter TP with an applicable filter factor to suppress cyclical fluctuations.
• a four-cylinder four-stroke engine is the current crankshaft speed of 180 degrees crankshaft rotation angle.
• the mean value MW1 of two crankshaft revolutions is formed by summing the filtered crankshaft speeds, divided by the number z of cylinders. This mean value MW1 is in each case added to the negated mean value of the filtered instantaneous crankshaft speeds of the same two crankshaft revolutions, resulting in the respective deviation of the filtered instantaneous crankshaft speeds from their mean value MW1.
• the integrator gain 1 is followed by an integrator control, which is extended by a delay element T, which ensures that the control loop is delayed by exactly 720 degrees crankshaft rotation angle.
• a limiting element B is provided within the integrator control, which serves to detect whether this is for one Cylinder-specific correction torque is at a limit used for diagnostic purposes.
• the cylinder-selective correction moments KM supplied to the limiting element B via the delay element T are expanded by the negated mean values MW2 of the correction moments KM for 720 degrees crankshaft rotation angle, as a result of which the sum of the tooth-selective correction moments KM executed is zero. This is done in accordance with the requirement that the operating state of the internal combustion engine desired by the driver must not be changed by equating the mean pressures.
• the individual cylinder adjustment is considered to have been successfully completed if the control deviation of all cylinders is below an applicable limit value for an applicable duration before an applicable period has elapsed.
• the purpose of the period for a control to expire is to end an unstable control process.
• the cylinder-selective correction torques KM are fed to the control device or determined and stored in the control device.
• the control unit takes the appropriate control value for the solenoid valves of the fuel supply from a characteristic map in order to supply the cylinders with exactly the amount of fuel for the operating state desired by the driver plus the determined, cylinder-selective correction moments KM.
• cylinder-selective correction moments are stored primarily (basic adjustment).
• further cylinder-selective correction moments can be saved as part of the inspections (customer service comparison), after repairs or after any period of time
• the cylinder-selective correction torques stored after the manufacture of the diesel engine additionally serve as comparison values for customer service comparison values determined, for example, during inspections. On the basis of such a comparison, damage to the diesel engine can be diagnosed at an early stage. For example, problems of fuel injection or tightness problems of the combustion chambers can be recognized if a correction torque for a cylinder increases beyond a limit value.
• FIG. 3a shows the mean pressures of a four-cylinder diesel engine without activated individual cylinder adjustment.
• the PMI 01 pressure column belonging to cylinder 1 has an approx. 20% lower value for the medium pressure than the other cylinders.
• FIG. 3b shows the medium pressures of this four-cylinder diesel engine with activated individual cylinder adjustment. All four cylinders have approximately the same value for the medium pressure
• the method according to the invention can be used differently in different speed ranges of the diesel engine on the basis of the single-cylinder adjustment by means of the PLD system, a control device, the measuring devices of the crankshaft and the camshaft.
• the method of the single-cylinder adjustment is modified to to obtain cylinder-specific correction values that bring about idle idle control.
• FIG. 4a shows the instantaneous crankshaft speeds over 720 degrees crankshaft rotation angle of an eight-cylinder diesel engine without idle idle control and in FIG. 4b with idle idle control
• the occurrence of vibrations of a vehicle with a diesel engine is strongly demanded by rotational irregularities in the crankshaft.
• the sensitivity to vibrations while the diesel engine is idling results from the small frequency difference between the natural frequencies of the rear-view mirrors, steering wheel, etc. and the diesel engine rotating at a standstill of approx. 600 crankshaft revolutions per minute.
• the idle idle control is initiated when the crankshaft speed is constantly below an applicable limit.
• the procedure is analogous to the individual cylinder adjustment. Only the characteristic size used and the gain factor of the integrator gain is adapted to the idle idle control.
• the control process of idle idle control is ended when the control deviations of all cylinders are below an applicable limit value. If this limit value is exceeded, idle idle control is reactivated.
• the result is cylinder-selective correction torques in accordance with the requirements of idle idle control.
• the requirement of idle idle control does not have to consist of equating the medium pressures, but can also relate to the equality of characteristics of the crankshaft speeds, while the partial / load operation of the diesel engine results in the equalization of the cylinder-selective Medium pressure due to the compensation of the component differences by means of the single-cylinder adjustment minimizes fuel consumption and a reduction in pollutant emissions.Through the more even load distribution, the reduction in the tendency to oscillate and the early detection of, for example, lack of compression, defects in the injection system or sensor malfunctions, the operating life of the diesel engine is increased Some areas of operation of the diesel engine can be specifically different loads on the cylinder due to the possible advantages in the operating behavior of the diesel engine can be achieved.
• the signals from the further inductive sensors of the crankshaft and camshaft can be used by the control device to check the synchronization between the crankshaft and the camshaft

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

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• 1996
  • 1996-08-16 DE DE19633066A patent/DE19633066C2/de not_active Expired - Fee Related
• 1997
  • 1997-08-09 AT AT97943802T patent/ATE237076T1/de not_active IP Right Cessation
  • 1997-08-09 US US09/051,638 patent/US6082330A/en not_active Expired - Lifetime
  • 1997-08-09 BR BR9706662A patent/BR9706662A/pt not_active IP Right Cessation
  • 1997-08-09 JP JP10510345A patent/JP2000500209A/ja active Pending
  • 1997-08-09 EP EP97943802A patent/EP0858555B1/de not_active Expired - Lifetime
  • 1997-08-09 WO PCT/EP1997/004350 patent/WO1998007971A2/de active IP Right Grant

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