Measuring and testing – Vehicle chassis – Steering
Reexamination Certificate
1997-12-12
2001-03-13
Fuller, Benjamin R. (Department: 2855)
Measuring and testing
Vehicle chassis
Steering
C073S116070
Reexamination Certificate
active
06199426
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of detection of output fluctuation in a multi-cylinder engine.
2. Description of the Related Art
Known in the art is an internal combustion engine which finds a first angular velocity of the crankshaft in the time required for the crankshaft to rotate from 30° to 60° after top dead center of the compression stroke from this period, finds a second angular velocity of the crankshaft in the time required for the crankshaft to rotate from 90° to 120° after top dead center of the compression stroke from this time, finds the torque generated by a cylinder from the square of the first angular velocity and the square of the second angular velocity, and calculates the amount of torque fluctuation from the amount of fluctuation of the generated torque (see Japanese Examined Patent Publication (Kokoku) No. 7-33809).
That is, when combustion is performed in a cylinder, the combustion pressure causes the angular velocity of the crankshaft to rise from a first angular velocity &ohgr;a to a second angular velocity &ohgr;b. At this time, if the moment of inertia of rotation of the engine is I, the combustion pressure causes the kinetic energy to rise from (½)·I&ohgr;a
2
to (½)·I&ohgr;b
2
. Roughly speaking, the amount of rise of the kinetic energy (½)·I·(&ohgr;b
2
−&ohgr;a
2
) causes a torque to be generated, so the generated torque becomes proportional to (&ohgr;b
2
−&ohgr;a
2
). Therefore, the generated torque is found from the difference between the square of the first angular velocity &ohgr;a and the square of the second angular velocity &ohgr;b and, therefore, in the above-mentioned internal combustion engine, the amount of torque fluctuation is calculated from the thus found generated torque.
However, if the generated torque is calculated based on the angular velocity &ohgr;a and &ohgr;b in this way, when for example the engine drive system experiences torsional vibration, the generated torque calculated based on the angular velocities &ohgr;a and &ohgr;b will no longer express the true generated torque. That is, when the engine drive system does not experience a torsional vibration, the second angular velocity &ohgr;b increases from the first angular velocity &ohgr;a by exactly the amount of increase of the angular velocity caused by the combustion pressure. As opposed to this, when the engine drive system experiences a torsional vibration, the second angular velocity &ohgr;b will include in addition to the amount of increase of the angular velocity caused by the combustion pressure the amount of change of the angular velocity caused by the torsional vibration of the engine drive system in the period from detection of the first angular velocity &ohgr;a to detection of the second angular velocity &ohgr;b. For example, if the angular velocity increased due to the torsional vibration of the engine drive system in the period from detection of the first angular velocity &ohgr;a to detection of the second angular velocity &ohgr;b, the amount of increase of the second angular velocity &ohgr;b with respect to the first angular velocity &ohgr;a will include in addition to the amount of increase of the angular velocity due to the combustion pressure the amount of increase of the angular velocity due to the torsional vibration of the engine drive system. Therefore, even if the amount of increase of the second angular velocity &ohgr;b due to the combustion pressure is constant when a torsional vibration occurs in the engine drive system, that is, even when there is no change in the generated torque, the generated torque calculated based on the angular velocities &ohgr;a, &ohgr;b will fluctuate and therefore there will be the problem that it will not be possible to calculate the true torque fluctuation.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method of detection of output fluctuation in a multi-cylinder engine which is capable of accurately detecting an output fluctuation and a torque fluctuation of an engine.
According to the present invention, there is provided a method of detection of output fluctuation of a multi-cylinder engine in which combustion is performed in a first cylinder and then combustion is performed in a second cylinder, comprising the steps of setting a first crank angle range in a crank angle region from the end of a compression stroke to the beginning of an expansion stroke for each cylinder, setting a second crank angle range in a crank angle region in the middle of the expansion stroke a predetermined crank angle away from the first crank angle range, detecting a first angular velocity of the crankshaft in the first crank angle range, detecting a second angular velocity of the crankshaft in the second crank angle range, finding an amount of change between the first angular velocity at the time of a previous combustion and the first angular velocity at the time of a next combustion for the first cylinder, finding an amount of change between the first angular velocity at the time of a previous combustion and the first angular velocity at the time of a next combustion for the second cylinder, finding an assumed second angular velocity at the time of the next combustion of the first cylinder when assuming that the output of the first cylinder will not fluctuate, on the basis of the amount of change of the first angular velocity for the first cylinder, the amount of change of the first angular velocity of the second cylinder, and the second angular velocity at the time of the previous combustion of the first cylinder, and detecting the output fluctuation of the first cylinder based on the assumed second angular velocity and the actual second angular velocity at the time of the next combustion of the first cylinder.
REFERENCES:
patent: 4691286 (1987-09-01), Obayashi et al.
patent: 4697561 (1987-10-01), Citron
patent: 4744243 (1988-05-01), Tanaka
patent: 5144927 (1992-09-01), Denz
patent: 5200899 (1993-04-01), Ribbens et al.
patent: 5574217 (1996-11-01), McCombie
patent: 5602331 (1997-02-01), Prevost
patent: 5652380 (1997-07-01), Machida
patent: 5670713 (1997-09-01), Machida et al.
patent: 41-38-765-A1 (1992-07-01), None
patent: 0-709-663-A1 (1996-05-01), None
patent: 2-291459 (1990-12-01), None
patent: 5-1614 (1993-01-01), None
patent: B2 7-33809 (1995-04-01), None
Davis Octavia
Fuller Benjamin R.
Oliff & Berridg,e PLC
Toyota Jidosha & Kabushiki Kaisha
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