Apparatus for Identifying a Non-Uniform Share of Cylinder Power in an Internal Combustion Piston Engine System
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Abstract
The invention utilizes the firing order of the cylinders within the engine to identify the cylinder or cylinders that mainly contribute or, alternatively, contribute as little as possible to the production of certain harmonic frequencies in the engine'"'"'s torque. In order to use the engine'"'"'s torque for this purpose, the calculation of torque must take into account the non-linearities of the engine system. Thus the calculation of torque takes into account not only the properties of the engine but also the properties of the load and the shaft.
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Citations
35 Claims
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1-17. -17. (canceled)
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18. A method for identifying at least one cylinder in an internal combustion piston engine, the power output of which deviates substantially from power outputs of the other cylinders, wherein the method comprises stages of
measuring angular velocity of the engine shaft and angular velocity of the shaft of a load connected to the engine shaft, determining amplitudes and phases of harmonic waves under examination on the basis of the angular velocity measurement data, determining an offset and angular acceleration of the engine shaft, as well as an offset of the load shaft at each harmonic wave of the angular velocities under examination, determining parameters of the coupling between the engine shaft and the load shaft at the harmonic frequencies under examination, calculating torques at the harmonic waves under examination by using the measured angular velocities, the determined offsets and angular accelerations of said shafts, as well as the coupling parameters, and identifying the cylinder or cylinders by comparing the calculated torques with a firing order of the engine'"'"'s cylinders, the coupling parameters to be determined are frequency-dependent rigidity and frequency-dependent damping of the coupling, and during the cylinder identification stage (66), the torque calculated at each harmonic wave is compared with ignition times of the cylinders in order to detect the cylinders that produce the most deviating amount of power at the harmonic wave in question, and the cylinder that is found to produce too much or too little power at all of the harmonic waves under examination is selected as the identified cylinder.
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27. An apparatus for identifying at least one of an internal combustion piston engine'"'"'s cylinders, power output of which deviates substantially from power outputs of the other cylinders, wherein the apparatus comprises a central unit with interfaces for measurement sensors and that through said interfaces, the central unit is arranged to receive and process measurement data on the angular velocity of the engine shaft and measurement data on the angular velocity of the load shaft connected to the engine shaft, measurement data incoming from measurement sensors connectable to the interfaces,
said central unit comprises means for determining amplitudes and phases of harmonic waves under examination on the basis of the angular velocity measurement data, second means for determining an offset and angular acceleration of the engine shaft, as well as an offset of the load shaft at each harmonic wave of the angular velocities under examination, third means containing information on dynamic parameters of the coupling between the engine shaft and the load shaft at the harmonic waves under examination, fourth means for calculating torques at the harmonic waves under examination by using the measured angular velocities, the determined offsets and angular accelerations of said shafts, as well as the coupling parameters, and fifth means for identifying the cylinder or cylinders by comparing the calculated torques with a firing order of the engine'"'"'s cylinders, the central unit is arranged or can be arranged to process the harmonic waves of angular velocities at a minimum of three lowest harmonic frequencies, and the dynamic parameters of the coupling are frequency-dependent rigidity and frequency-dependent damping, and the fifth means are arranged to identify the cylinder that is found to produce too much or too little power at all of the harmonic waves under examination.
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35. A method of operating a multi-cylinder internal combustion piston engine having an engine shaft coupled to a load shaft for driving a load, wherein each cylinder produces a power output and the engine shaft and the load shaft each rotate with an angular velocity that varies periodically, said method comprising:
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measuring the angular velocity of the engine shaft and the angular velocity of the load shaft, determining amplitudes and phases of selected harmonic frequencies of the periodic variations of the angular velocities of the engine shaft and load shaft, determining an offset and angular acceleration of the engine shaft, as well as an offset of the load shaft at each of said selected harmonic frequencies of the angular velocities, determining parameters of the coupling between the engine shaft and the load shaft at the selected harmonic frequencies, the coupling parameters being frequency-dependent rigidity and frequency-dependent damping of the coupling, calculating torques at the selected harmonic frequencies by using the measured angular velocities, the determined offsets and angular accelerations of said shafts, as well as the coupling parameters, and identifying at least one cylinder of which the power output deviates substantially from the power outputs of other cylinders of the engine, by comparing the calculated torques with a firing order of the engine'"'"'s cylinders, wherein the step of identifying at least one cylinder includes comparing the torque calculated at each selected harmonic frequency with ignition times of the cylinders in order to detect the cylinder that produces the most deviating amount of power at each selected harmonic frequency, and the method further comprises identifying the cylinder that produces too much or too little power at all of the selected harmonic frequencies as a cylinder of which the power output deviates substantially from power outputs of the other cylinders.
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Specification