Abstract:
A method for detecting combustion misfires in an internal combustion engine is based on the speed of rotation of the crankshaft. An unsteady running value is derived from measured cylinder segment times and subsequent correction of mechanical teeth defects. A disturbance caused by torsional oscillations of the crankshaft is taken into account by a cylinder-selective disturbance variable compensation dependent on load and speed of rotation.
Abstract:
A method for detecting combustion misfires in internal combustion engines includes calculating a non-concentricity value from fluctuations in angular speed of a crankshaft, and dropping the non-concentricity value below a negative non-concentricity limit value if a combustion misfire is present. If the non-concentricity value drops below the non-concentricity limit value, a value for a stretch of bad road is calculated from successively calculated non-concentricity values, and the value for a stretch of bad road is dropped below or made of equal magnitude to a positive limit value for a stretch of bad road, if a stretch of bad road is present. The previously indicated combustion misfire is not confirmed if the value for a stretch of bad road drops below or is of equal magnitude to the limit value for a stretch of bad road. However, the previously indicated combustion misfire is confirmed if the value for a stretch of bad road exceeds the limit value for a stretch of bad road.
Abstract:
An adaptation method for correcting tolerances of a transducer wheel includes determining a correction factor for each individual tooth or each segment of the transducer wheel by measuring angular speed while taking into account both production tolerances and variations from one manufactured part to another of its kind as well as noncentral support of the transducer wheel on the shaft. The correction factor also compensates for a mass moment caused by a piston and a connecting rod. In an adaptation algorithm, a periodic disturbance by a gas moment caused by varying cylinder pressures and a moment fed back from the road are taken into account.
Abstract:
A method for identifying misfiring is employed in an internal combustion engine with multiple cylinders. The identification is effected by measuring segment times required for the crankshaft to rotate about given angular segments during the cylinder work cycle. Any fluctuations are then calculated and compared with threshold values. During thrust cutoff, i.e. when no fuel is supplied to the cylinders, errors in the segment time measurement are identified and corrected, and in dependence of the number of the completed cycles for calculating the correction factors, the threshold values are modified.
Abstract:
A method for identifying and correcting errors in time measurement on rotating shafts, particularly on crankshafts or shafts connected thereto in internal combustion engines, whereby the shafts are provided with marks which are scanned with sensors. The segment times required by the shaft to rotate about a defined angular distance are measured and compared with a reference segment.
Abstract:
During the warm-up phase of a catalytic converter, the fuel-oxygen ratio in the exhaust gas upstream of the catalytic converter is regulated in dependence on the temperature of the catalytic converter. The amount of fuel is measured on the basis of an injection time into the internal combustion engine. The injection time is calculated from a basic injection time weighted with a weighting factor. The weighting factor depends on the secondary air mass which is delivered to the exhaust gas duct and on a predetermined set value for the fuel-oxygen ratio of the exhaust gas (.DELTA.value) upstream of the catalytic converter. The secondary air mass is regulated in dependence on an engine air intake.
Abstract:
A method for detecting oscillations of a crankshaft of an internal combustion engine includes determining if an engine is within a predetermined rpm range. An amplitude of a crankshaft vibration is ascertained if the engine is within the predetermined rpm range. A determination is made as to whether or not the amplitude is greater than a limit value. A frequency of the crankshaft vibration is ascertained if the amplitude is greater than the limit value. A determination is made as to whether or not the frequency is within a predetermined frequency range. An oscillation of the crankshaft is ascertained and a process for detecting combustion misfires by evaluating fluctuations in the crankshaft speed is suppressed for a predeterminable period of time, if the frequency is within the predetermined frequency range.
Abstract:
A method for detecting combustion misfires includes calculating engine roughness values from fluctuations in crankshaft rpm, comparing the values with threshold values, and forming cylinder groups having an increased likelihood of misfiring. During a period of observation, each engine roughness value calculated for each cylinder is separately compared with a first threshold value and with a second threshold value being reduced in comparison with the first threshold value, a first counting sum associated with the cylinder is formed if the first threshold value is exceeded, and a second counting sum associated with the cylinder is formed if the second threshold value is exceeded. After the period of observation has elapsed, if the total sums of all of the first or second counting sums exceed a predeterminable total sum limit value, group sums are formed for each cylinder group from the second counting sums, and a conclusion is drawn as to the occurrence of a multi-cylinder misfire in the group having the higher group sum if the second counting sums of the individual cylinders in a group are approximately of equal magnitude, and conversely, if the second counting sums of the various cylinders are different, a conclusion is drawn as to a single-cylinder combustion misfire for the cylinder having the highest first counting sum, if the total sum of the first counting sums exceeds a predeterminable total sum limit value.
Abstract:
Nonconcentricity or lack of smoothness values are proportional to the change in angular speed of the crankshaft. Deviation values that are proportional to the cyclical combustion fluctuations are ascertained, after the nonconcentricity values of successive combustion cycles are averaged, by comparison of the current nonconcentricity value with the associated mean value. Then the deviation quantity is compared with an individual-cylinder-specific limit value, and cyclical combustion fluctuations are deduced if the deviation quantity exceeds a limit value.
Abstract:
A method for recognizing stretches of rough or bad road includes recognizing tank pressure values at successive evaluation instants. A change in tank pressure is ascertained from successive tank pressure values. A stretch of rough or bad road is recognized if the change exceeds a limit value.