Apparatus and method for detecting misfires in internal combustion engine
First Claim
1. An apparatus for detecting misfires in an internal combustion engine of a vehicle, the apparatus comprising:
- a plurality of cylinders defined in the engine;
a piston accommodated in each cylinder to reciprocate in the cylinder;
a shaft connected with the pistons, the shaft being rotated by reciprocal movement of the pistons;
a speed sensor for detecting the rotating speed of the shaft;
a deviation computer for computing a deviation between earlier and later times of the rotating speed of the shaft at a selected portion of a cycle of a selected piston based on the detected speed of the shaft, wherein the deviation is affected by the load on the engine;
setting means for setting a learning value based on the computed deviation, wherein the learning value is a reference value used for detecting misfires in the cylinders;
a memory for storing the learning value;
a condition sensor for detecting a running condition of the engine, wherein the condition is indicative of the load of the engine;
learning means for renewing the learning value stored in the memory based on the detected condition of the engine;
a first determiner for determining whether a misfire has occurred in each cylinder based on a difference between the computed deviation and the learning value; and
means for permitting the renewing of the learning value by the learning means only when the engine load is less than a predetermined value that is determined by the rotating seed of the shaft.
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Accused Products
Abstract
An apparatus for detecting misfires in an internal combustion engine that is mounted on a vehicle. A plurality of cylinders is defined in the engine, and a piston accommodated in each cylinder to reciprocate in the cylinder. A crankshaft is connected with the piston, the crankshaft is rotated by the reciprocal movement of the piston. An engine speed sensor is provided for detecting the rotating speed of the crankshaft. An electronic control unit (ECU) computes the deviation of rotating speed of the crankshaft corresponding to each cylinder based on the detected engine speed, and the deviation is proportional to the engine load. The ECU costs a leaning value based on the computed deviation, wherein the learning value is used for detecting the misfires in the engine. A memory is provided for storing the learning value. Several sensors are provided for detecting a running condition of the engine, wherein the condition is included the engine load. The ECU renews the learning value stored in the memory based on the detected condition of the engine. The ECU determines whether the misfires occurs in each cylinder based on the difference between the deviation and the learning value. The ECU renews the learning value when the engine load is less than a predetermined value.
31 Citations
40 Claims
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1. An apparatus for detecting misfires in an internal combustion engine of a vehicle, the apparatus comprising:
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a plurality of cylinders defined in the engine; a piston accommodated in each cylinder to reciprocate in the cylinder; a shaft connected with the pistons, the shaft being rotated by reciprocal movement of the pistons; a speed sensor for detecting the rotating speed of the shaft; a deviation computer for computing a deviation between earlier and later times of the rotating speed of the shaft at a selected portion of a cycle of a selected piston based on the detected speed of the shaft, wherein the deviation is affected by the load on the engine; setting means for setting a learning value based on the computed deviation, wherein the learning value is a reference value used for detecting misfires in the cylinders; a memory for storing the learning value; a condition sensor for detecting a running condition of the engine, wherein the condition is indicative of the load of the engine; learning means for renewing the learning value stored in the memory based on the detected condition of the engine; a first determiner for determining whether a misfire has occurred in each cylinder based on a difference between the computed deviation and the learning value; and means for permitting the renewing of the learning value by the learning means only when the engine load is less than a predetermined value that is determined by the rotating seed of the shaft. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method for detecting misfires in an internal combustion engine, the engine having a plurality of cylinders defined in the engine, a piston accommodated in each cylinder to reciprocate in the cylinder, and a shaft connected with each piston, the shaft being rotated by the reciprocal movement of each piston, the method comprising:
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detecting the rotating speed of the shaft; computing a deviation between an earlier time and a later time of the rotating speed of the shaft for a selected portion of a cycle of a selected cylinder based on the detected speed of the shaft; setting a learning value based on the computed deviation, wherein the learning value is used for detecting the misfires in the engine; storing the learning value in a memory; detecting a running condition of the engine, wherein the running condition is indicative of the load on the engine; renewing the learning value stored in the memory based on the detected condition of the engine; determining whether a misfire has occurred in the selected cylinder based on a difference between the deviation and the learning value; and permitting the renewing of the learning value by the learning means only when the engine load is less than a predetermined value that is determined by the rotating speed of the shaft. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31)
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32. An apparatus for detecting misfires in an internal combustion engine of a vehicle, the apparatus comprising:
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a plurality of cylinders defined in the engine; a piston accommodated in each cylinder to reciprocate in the cylinder; a shaft connected with the pistons, the shaft being rotated by reciprocal movement of the pistons; a speed sensor for detecting the rotating speed of the shaft; a deviation computer for computing a deviation between earlier and later times of the rotating speed of the shaft at a selected portion of a cycle of a selected piston based on the detected speed of the shaft; setting means for setting a learning value based on the computed deviation, wherein the learning value is a reference value used for detecting misfires in the cylinders, the learning value being set while the engine is under load and during fuel combustion; a memory for storing the learning value; and a first determiner for determining whether a misfire has occurred in the cylinder with the selected piston based on a difference between the computed deviation and the learning value, wherein the engine is cooled by coolant, coolant temperature is divided into a plurality of temperature ranges, and the learning value is set for each temperature range.
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33. An apparatus for detecting misfires in an internal combustion engine of a vehicle, the apparatus comprising:
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a plurality of cylinders defined in the engine; a piston accommodated in each cylinder to reciprocate in the cylinder; a shaft connected with the pistons, the shaft being rotated by reciprocal movement of the pistons and having a range of rotating speeds, the range of rotating speeds being divided into a plurality of sub-ranges; a speed sensor for detecting the rotating speed of the shaft; a deviation computer for computing a deviation between earlier and later times of the rotating speed of the shaft at a selected portion of a cycle of a selected piston based on the detected speed of the shaft; setting means for setting a learning value based on the computed deviation, wherein the learning value is a reference value used for detecting misfires in the cylinders, the learning value being set while the engine is under load and during fuel combustion; a memory for storing the learning value; and a first determiner for determining whether a misfire has occurred in the cylinder with the selected piston based on a difference between the computed deviation and the learning value, wherein the learning value is set for each sub-range, with each sub-range including a learning range within which the renewing of the learning value is permitted and a prohibiting range in which the renewing of the learning value is prohibited, each learning range being narrower than the speed sub-range within which it is included.
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34. An apparatus for detecting misfires in an internal combustion engine of a vehicle, the apparatus comprising:
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a plurality of cylinders defined in the engine; a piston accommodated in each cylinder to reciprocate in the cylinder; a shaft connected with the pistons, the shaft being rotated by reciprocal movement of the pistons and having a range of rotating speeds, the range of rotating speeds being divided into a plurality of sub-ranges; a speed sensor for detecting the rotating speed of the shaft; a deviation computer for computing a deviation between earlier and later times of the rotating speed of the shaft at a selected portion of a cycle of a selected piston based on the detected speed of the shaft; setting means for setting a learning value based on the computed deviation, wherein the learning value is a reference value used for detecting misfires in the cylinders; a memory for storing the learning value; a condition sensor for detecting a running condition of the engine, wherein the condition is indicative of the load of the engine; learning means for renewing the learning value stored in the memory based on the detected condition of the engine; a first determiner for determining whether a misfire has occurred in the cylinder with the selected piston based on a difference between the computed deviation and the learning value; and prohibiting means for prohibiting the renewing of the learning value, wherein the learning value has an initial value and is set for each sub-range, and when a renewed learning value in one speed range is changed rapidly from a previous learning value, the learning means sets the learning value to the initial value in every other speed range and the prohibiting means prohibits the renewal of the learning value in all of the speed ranges.
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35. An apparatus for detecting misfires in an internal combustion engine of a vehicle, the apparatus comprising:
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a plurality of cylinders defined in the engine; a piston accommodated in each cylinder to reciprocate in the cylinder; a shaft connected with the pistons, the shaft being rotated by reciprocal movement of the pistons and having a range of rotating speeds, the range of rotating speeds being divided into a plurality of sub-ranges; a speed sensor for detecting the rotating speed of the shaft; a deviation computer for computing a deviation between earlier and later times of the rotating speed of the shaft at a selected portion of a cycle of a selected piston based on the detected speed of the shaft; setting means for setting a learning value based on the computed deviation, wherein the learning value is a reference value used for detecting misfires in the cylinders; a memory for storing the learning value; a condition sensor for detecting a running condition of the engine, wherein the condition is indicative of the load of the engine; learning means for renewing the learning value stored in the memory based on the detected condition of the engine; a first determiner for determining whether a misfire has occurred in the cylinder with the selected piston based on a difference between the computed deviation and the learning value; and means for permitting the renewing of the learning value by the learning means only when the engine load is less than a predetermined value, wherein the learning value is set for each sub-range and the permitting means allows the first determiner to determine whether misfires have occurred in the speed range to which the renewed learning value belongs when an initial renewed learning value is substantially equal to the most recent learning value. - View Dependent Claims (36)
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37. An apparatus for detecting misfires in an internal combustion engine of a vehicle, the apparatus comprising:
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a plurality of cylinders defined in the engine; a piston accommodated in each cylinder to reciprocate in the cylinder; a shaft connected with the pistons, the shaft being rotated by reciprocal movement of the pistons; a speed sensor for detecting the rotating speed of the shaft; a deviation computer for computing a deviation between earlier and later times of the rotating speed of the shaft at a selected portion of a cycle of a selected piston based on the detected speed of the shaft, wherein the deviation is affected by the load on the engine; setting means for setting a learning value based on the computed deviation, wherein the learning value is a reference value used for detecting misfires in the cylinders; a memory for storing the learning value; a condition sensor for detecting a running condition of the engine, wherein the condition is indicative of the load of the engine; learning means for renewing the learning value stored in the memory based on the detected condition of the engine; and a first determiner for determining whether a misfire has occurred in each cylinder based on a difference between the computed deviation and the learning value, wherein the learning means renews the learning value based on a most recent learning value and a previous learning value, the renewed learning value being a function of the most recent learning value and the previous learning value, the function being changed when a current learning value is drastically changed from the previous learning value. - View Dependent Claims (38)
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39. A method for detecting misfires in an internal combustion engine, the engine being cooled by coolant and having a plurality of cylinders defined in the engine, a piston accommodated in each cylinder to reciprocate in the cylinder, and a shaft connected with each piston, the shaft being rotated by the reciprocal movement of each piston, the method comprising:
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detecting the rotating speed of the shaft; computing the deviation between an earlier time and a later time of the rotating speed of the shaft for a selected portion of a cycle of a selected cylinder based on the detected speed of the shaft; dividing a temperature range of the coolant into a plurality of sub-ranges; setting a learning value for each sub-range based on the computed deviation, wherein the learning value is used for detecting the misfires in the engine, the learning value being set during fuel combustion and while the engine is loaded; storing the learning value in a memory; and determining whether a misfire has occurred in the selected cylinder based on a difference between the deviation and the learning value.
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40. A method for detecting misfires in an internal combustion engine, the engine having a plurality of cylinders defined in the engine, a piston accommodated in each cylinder to reciprocate in the cylinder, and a shaft connected with each piston, the shaft having a range of rotating speeds and being rotated by the reciprocal movement of each piston, the range being divided into a plurality of speed sub-ranges, the method comprising:
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detecting the rotating speed of the shaft; computing the deviation between an earlier time and a later time of the rotating speed of the shaft for a selected portion of a cycle of a selected cylinder based on the detected speed of the shaft; setting a learning value for each speed sub-range based on the computed deviation, wherein the learning value is used for detecting the misfires in the engine, the learning value being set during fuel combustion and while the engine is loaded, each speed sub-range including a learning range within which renewal of the learning value is permitted and a prohibiting range in which the renewing of the learning value is prohibited, each learning range being narrower than the speed sub-range within which it is included; storing the learning value in a memory; and determining whether a misfire has occurred in the selected cylinder based on a difference between the deviation and the learning value.
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Specification