JP2004060579A - Method and device for diagnosing of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for diagnosing an internal combustion engine capable of easily and accurately diagnosing a crank angle sensor and a cam angle sensor for abnormalities. <P>SOLUTION: In this diagnosing method for the internal combustion engine, the crank angle sensor detecting the speed of the crankshaft of the internal combustion engine and the cam angle sensor detecting the rotating angle of the camshaft drivingly connected to the crankshaft are diagnosed for presence or absence of the abnormalities. First it is determined whether the correspondence of an output from the crank angle sensor to an output from the cam angle sensor is normal or not. When the correspondence of these outputs is determined abnormal, it is determined whether or not an engine speed NECAM obtained based on the output from the cam angle sensor at the cranking of the internal combustion engine comes within the range (determined value α ≤ NECAM ≤ determined value β) of the engine speed experimentally defined as the speed of the internal combustion engine at the cranking. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and a device for diagnosing an internal combustion engine, and more particularly to a method and a device for diagnosing abnormalities in a crank angle sensor and a cam angle sensor for detecting rotation angles of a crank shaft and a cam shaft of the engine, respectively. .
[0002]
[Prior art]
In general, in an internal combustion engine, a fuel ignition timing, an injection timing, and the like are set in accordance with a rotation angle of a crankshaft, which is an engine output shaft, that is, a crank angle. This crank angle is actually obtained from a crank angle signal output from a crank angle sensor that detects the rotation angle of the crankshaft and a cam angle sensor that detects the rotation angle of a camshaft drivingly connected to the crankshaft. It is calculated based on the output cam angle signal (cylinder discrimination signal). Therefore, even if an abnormality occurs in one of the crank angle sensor and the cam angle sensor, it is not possible to calculate an accurate crank angle, which also hinders ignition timing control and injection timing control of the internal combustion engine. Become like
[0003]
Therefore, conventionally, in order to prevent such erroneous detection of the crank angle, various devices for diagnosing the abnormality of the crank angle sensor and the cam angle sensor have been proposed. As one of them, for example, in an apparatus described in Japanese Patent Application Laid-Open No. 2-275044, the correspondence between the output pulse of the cam angle sensor and the output pulse of the crank angle sensor is patterned. Then, by comparing this pattern with a predetermined reference pattern, the presence or absence of an abnormality is individually diagnosed for each of the cam angle sensor and the crank angle sensor.
[0004]
[Problems to be solved by the invention]
By patterning the correspondence between the output pulse of the cam angle sensor and the output pulse of the crank angle sensor as in the device described in the above-mentioned publication, even if an abnormality occurs in any of those sensors, any abnormality is detected. It is certainly possible to identify which sensor is occurring. However, in any environment where these sensors are arranged, the effects of noise cannot be ignored, and if pulse-like noise is superimposed on those output pulses, the reliability of the pattern itself will be greatly increased. Will be reduced. Further, for example, when a break occurs in the ground wire of the cam angle sensor, a large number of pulse signals output from the crank angle sensor are superimposed as noise on the output pulse of the cam angle sensor. In such a case, the abnormality diagnosis itself by the pattern comparison becomes difficult.
[0005]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method and apparatus for diagnosing an internal combustion engine that can more easily and accurately perform abnormality diagnosis of a crank angle sensor and a cam angle sensor. It is in.
[0006]
[Means for Solving the Problems]
The means for achieving the above object and the effects thereof will be described below.
The invention according to claim 1 determines whether or not a crank angle sensor for detecting a rotation speed of a crankshaft of an internal combustion engine and a cam angle sensor for detecting a rotation angle of a camshaft drivingly connected to the crankshaft are abnormal. In the diagnosis method for an internal combustion engine to be diagnosed, based on a comparison between an engine rotation speed obtained based on the output of the cam angle sensor during cranking of the internal combustion engine and an engine rotation speed empirically determined as the rotation speed during cranking. The gist of the present invention is to diagnose at least whether or not the cam angle sensor is abnormal.
[0007]
In this diagnostic method, at least the abnormality of the cam angle sensor is determined by comparing the actual engine speed during cranking obtained based on the output of the cam angle sensor with the engine speed during cranking that is determined empirically. The presence or absence is diagnosed. Here, it is known that the engine speed at the time of cranking is substantially constant, and this speed can be known empirically. It is also easy to calculate the engine speed from the output of the cam angle sensor. For this reason, the actual engine speed can also be easily compared with the empirically determined engine speed, and the actual engine speed at the time of cranking is determined by the empirically determined engine speed at the time of cranking. When the speed is not equivalent, it can be diagnosed that at least the cam angle sensor is abnormal. Therefore, according to the above-described diagnosis method, at least abnormality diagnosis of the cam angle sensor can be easily and accurately performed.
[0008]
According to a second aspect of the present invention, in the method for diagnosing an internal combustion engine according to the first aspect, prior to the diagnosis, it is determined whether the correspondence between the output of the crank angle sensor and the output of the cam angle sensor is normal or abnormal. The gist is that the diagnosis is executed only when it is determined that the correspondence between the outputs is abnormal.
[0009]
According to the diagnostic method, when the correspondence between the output of the crank angle sensor and the output of the cam angle sensor is determined to be normal, the diagnosis described in claim 1 is not executed. Therefore, the diagnostic load when both the crank angle sensor and the cam angle sensor are normal is reduced.
[0010]
According to a third aspect of the present invention, in the method for diagnosing an internal combustion engine according to the second aspect, an engine speed determined based on an output of the cam angle sensor is used as the cranking speed during the execution of the diagnosis. Diagnosing that the crank angle sensor is abnormal based on the determination that the engine rotational speed falls within the range of the engine rotational speed determined empirically, the engine rotational speed obtained based on the output of the cam angle sensor determines the rotational speed during cranking. The gist of the invention is to diagnose that the cam angle sensor is abnormal based on the determination that the engine speed is out of the range of the engine rotational speed empirically determined as the speed.
[0011]
According to the diagnostic method, after it is determined that the correspondence between the output of the crank angle sensor and the output of the cam angle sensor is abnormal, the engine rotational speed obtained based on the output of the cam angle sensor is used as the rotational speed during cranking. It is determined whether or not it falls within a range of the engine rotational speed that is determined in advance. If the engine rotation speed obtained based on the output of the cam angle sensor is out of the range of the engine rotation speed empirically determined as the rotation speed at the time of cranking, it is diagnosed that the cam angle sensor is abnormal. . On the other hand, if the engine rotation speed obtained based on the output of the cam angle sensor falls within the range of the engine rotation speed empirically determined as the rotation speed during cranking, the cam angle sensor is diagnosed as normal. In other words, when the cam angle sensor is normal, the result of the determination that the correspondence between the output of the crank angle sensor and the output of the cam angle sensor is determined to be abnormal is accurately caused by the abnormality of the crank angle sensor. Is diagnosed.
[0012]
According to a fourth aspect of the present invention, there is provided a crank angle sensor for detecting a rotation speed of a crankshaft of an internal combustion engine and a cam angle sensor for detecting a rotation angle of a camshaft drivingly connected to the crankshaft. In the diagnosis method for an internal combustion engine to be diagnosed, based on a comparison between an engine rotation speed obtained based on an output of the crank angle sensor during cranking of the internal combustion engine and an engine rotation speed empirically determined as the rotation speed during cranking. The gist of the present invention is to diagnose at least whether or not the crank angle sensor is abnormal.
[0013]
In this diagnostic method, at least the abnormality of the crank angle sensor is determined by comparing the actual engine speed during cranking obtained based on the output of the crank angle sensor with the engine speed during cranking that is determined empirically. The presence or absence is diagnosed. Here, as described above, the engine speed during cranking is known to be substantially constant, and this speed can be known empirically. It is also easy to calculate the engine speed from the output of the crank angle sensor. For this reason, the actual engine speed can also be easily compared with the empirically determined engine speed, and the actual engine speed at the time of cranking is determined by the empirically determined engine speed at the time of cranking. If the speed is not equivalent, it can be diagnosed that at least the crank angle sensor is abnormal. Therefore, according to the above-described diagnosis method, at least abnormality diagnosis of the crank angle sensor can be easily and accurately performed.
[0014]
According to a fifth aspect of the present invention, in the method for diagnosing an internal combustion engine according to the fourth aspect, prior to the diagnosis, it is determined whether the correspondence between the output of the crank angle sensor and the output of the cam angle sensor is normal or abnormal. The gist is that the diagnosis is executed only when it is determined that the correspondence between the outputs is abnormal.
[0015]
According to the diagnostic method, when it is determined that the correspondence between the output of the crank angle sensor and the output of the cam angle sensor is normal, the diagnosis described in claim 4 is not executed. Therefore, the diagnostic load when both the crank angle sensor and the cam angle sensor are normal is reduced.
[0016]
According to a sixth aspect of the present invention, in the method for diagnosing an internal combustion engine according to the fifth aspect, an engine speed determined based on an output of the crank angle sensor is used as the rotation speed during the cranking when the diagnosis is performed. Diagnosing that the cam angle sensor is abnormal based on the determination that the engine rotation speed falls within the range of the engine rotation speed determined empirically, the engine rotation speed obtained based on the output of the crank angle sensor determines the rotation speed during cranking. The gist is to diagnose that the crank angle sensor is abnormal based on the determination that the engine speed is out of the range of the engine rotational speed empirically determined as the speed.
[0017]
According to the diagnostic method, after it is determined that the correspondence between the output of the crank angle sensor and the output of the cam angle sensor is abnormal, the engine rotation speed obtained based on the output of the crank angle sensor is used as the rotation speed during cranking. It is determined whether or not it falls within a range of the engine rotational speed that is determined in advance. If the engine rotation speed obtained based on the output of the crank angle sensor is out of the range of the engine rotation speed empirically determined as the rotation speed during cranking, it is diagnosed that the crank angle sensor is abnormal. . On the other hand, if the engine rotation speed obtained based on the output of the crank angle sensor falls within the range of the engine rotation speed empirically determined as the rotation speed during cranking, the crank angle sensor is diagnosed as normal. That is, when the crank angle sensor is normal, the result of the determination that the correspondence between the output of the crank angle sensor and the output of the cam angle sensor is abnormal is accurately determined to be due to the abnormality of the cam angle sensor. Is diagnosed.
[0018]
According to a seventh aspect of the present invention, there is provided a crank angle sensor for detecting a rotation speed of a crankshaft of an internal combustion engine and a cam angle sensor for detecting a rotation angle of a camshaft drivingly connected to the crankshaft. In the diagnostic device for an internal combustion engine to be diagnosed, a first determination unit that determines whether a correspondence between an output of the crank angle sensor and an output of the cam angle sensor is normal or abnormal, and the correspondence is determined by the first determination unit. On condition that it is determined to be abnormal, the engine speed determined based on the output of the cam angle sensor during cranking of the internal combustion engine and the engine speed determined empirically as the cranking speed. The gist of the present invention is to provide a second determination unit that determines which of the crank angle sensor and the cam angle sensor is abnormal in comparison.
[0019]
According to this configuration, the first determination unit first determines whether there is an abnormality in at least one of the crank angle sensor and the cam angle sensor. The actual cranking calculated based on the output of the cam angle sensor on condition that at least one of the crank angle sensor and the cam angle sensor is determined to be abnormal by the first determination means. The engine speed at the time is compared with the engine speed at the time of cranking which is determined empirically. Therefore, when the engine speed at the time of actual cranking is not the speed corresponding to the engine speed at the time of cranking determined empirically, it can be determined that the cam angle sensor is abnormal. On the other hand, when the engine speed at the time of actual cranking is the speed corresponding to the engine speed at the time of cranking which is also determined empirically, the cam angle sensor can be determined to be normal. When the cam angle sensor is normal as described above, the result of the determination that at least one of the crank angle sensor and the cam angle sensor is abnormal by the first determination means is determined by the crank angle sensor. It can be determined that the cause is an abnormality. Further, the calculation of the engine speed based on the output of the cam angle sensor and the comparison between the actual engine speed and the above-mentioned empirically determined engine speed can be easily performed. Therefore, according to the configuration of the seventh aspect, abnormality diagnosis of the crank angle sensor and the cam angle sensor can be easily and accurately performed.
[0020]
The invention according to claim 8 is based on a crank angle sensor for detecting a rotation speed of a crankshaft of an internal combustion engine and a cam angle sensor for detecting a rotation angle of a camshaft drivingly connected to the crankshaft. In the diagnostic device for an internal combustion engine to be diagnosed, a first determination unit that determines whether a correspondence between an output of the crank angle sensor and an output of the cam angle sensor is normal or abnormal, and the correspondence is determined by the first determination unit. On condition that it is determined to be abnormal, the engine speed determined based on the output of the crank angle sensor during cranking of the internal combustion engine and the engine speed determined empirically as the cranking speed. The gist of the present invention is to provide a second determination unit that determines which of the crank angle sensor and the cam angle sensor is abnormal in comparison.
[0021]
According to this configuration, the first determination unit first determines whether there is an abnormality in at least one of the crank angle sensor and the cam angle sensor. Then, on the condition that at least one of the crank angle sensor and the cam angle sensor is determined to be abnormal by the first determining means, the actual cranking calculated based on the output of the crank angle sensor is performed. The engine speed at the time is compared with the engine speed at the time of cranking determined empirically. Therefore, when the engine speed at the time of actual cranking is not the speed corresponding to the engine speed at the time of cranking that is empirically determined, it can be determined that the crank angle sensor is abnormal. On the other hand, when the engine speed at the time of actual cranking is a speed corresponding to the engine speed at the time of cranking, which is also determined empirically, the crank angle sensor can be determined to be normal. When the crank angle sensor is normal as described above, the result of the determination that at least one of the crank angle sensor and the cam angle sensor is abnormal by the first determination means is determined by the cam angle sensor. It can be determined that the cause is an abnormality. Furthermore, the calculation of the engine speed based on the output of the crank angle sensor and the comparison between the actual engine speed and the empirically determined engine speed can be easily performed. Therefore, according to the configuration of the eighth aspect, abnormality diagnosis of the crank angle sensor and the cam angle sensor can be easily and accurately performed.
[0022]
According to a ninth aspect of the present invention, in the diagnostic device for an internal combustion engine according to the seventh or eighth aspect, the second determination means monitors a voltage applied to a starter motor which is a cranking power source of the internal combustion engine. The gist of the present invention is to execute the determination on condition that the voltage to be monitored is equal to or higher than a predetermined value.
[0023]
Generally, the engine rotation speed when the internal combustion engine is cranked by the starter motor is affected by the voltage applied to the starter motor, and when the voltage is less than a predetermined value, the engine rotation speed assumed above is reduced. May not be obtained. Therefore, in the configuration of the ninth aspect, the determination by the second determination unit is performed on condition that the voltage applied to the starter motor is equal to or more than a predetermined value. Therefore, the above-described determination is performed only when the engine rotation speed at the time of cranking is stable, and the determination accuracy is naturally kept high.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment embodying a diagnosis method and a diagnosis device for an internal combustion engine according to the present invention will be described in detail with reference to FIGS.
[0025]
FIG. 1 is a schematic configuration diagram showing a gasoline engine 1 to which the diagnostic method and the diagnostic device are applied, and a peripheral configuration thereof.
The gasoline engine 1 has a plurality of cylinders, and the cylinder block 2 is provided with a plurality of cylinders 4 (only one is shown in FIG. 1 for convenience). A piston 5 is provided in the cylinder 4, and the piston 5 is connected via a connecting rod 6 to a crankshaft 7 which is an engine output shaft.
[0026]
A cylinder head 3 is mounted on the upper part of the cylinder block 2. A combustion chamber 8 is formed between the upper end of the piston 5 and the cylinder head 3 in the cylinder 4. The cylinder head 3 is provided with spark plugs 11 for spark ignition of the air-fuel mixture in the combustion chamber 8 for each cylinder.
[0027]
The cylinder head 3 is provided with an intake port 9 as an intake flow path to the combustion chamber 8 and an exhaust port 10 as an exhaust flow path from the combustion chamber 8 for each cylinder. ing. The fuel injection valve 35 provided for each cylinder injects fuel toward the inside of the intake port 9. The intake port 9 and the exhaust port 10 are connected to an intake passage 20 and an exhaust passage 30, respectively. A throttle valve 23 whose opening is adjusted by an actuator 22 driven based on, for example, operation of an accelerator pedal (not shown) is provided in the intake passage 20. By changing the opening of the throttle valve 23, the amount of air taken into the combustion chamber 8 is adjusted.
[0028]
On the other hand, an intake-side timing pulley 15 and an exhaust-side timing pulley 16 are drivingly connected to the crankshaft 7 via a timing belt 14. An intake camshaft 17 that rotates integrally with the intake-side timing pulley 15 is attached to the intake-side timing pulley 15. An exhaust camshaft 18 that rotates integrally with the exhaust-side timing pulley 16 is attached to the exhaust-side timing pulley 16.
[0029]
An intake valve 12 and an exhaust valve 13 provided corresponding to the combustion chamber 8 open and close the intake port 9 and the exhaust port 10, respectively. The intake valve 12 and the exhaust valve 13 are opened and closed by cams (not shown) provided on the intake camshaft 17 and the exhaust camshaft 18, respectively. Further, when the crankshaft 7 makes two rotations, the intake-side timing pulley 15 and the exhaust-side timing pulley 16 each make one rotation. Therefore, the intake valve 12 and the exhaust valve 13 are opened and closed at a predetermined timing in synchronization with the rotation of the crankshaft 7, that is, in response to the reciprocating movement of the piston 5.
[0030]
The crankshaft 7 is provided with a crank pulser 41 that can rotate integrally with the crankshaft 7, and a crank angle sensor 40 is provided near the crank pulser 41.
[0031]
FIG. 2A shows a configuration and an arrangement diagram of the crank angle sensor 40 and the crank pulser 41. The crank angle sensor 40 outputs a pulse signal each time a plurality of teeth 41a formed on the outer peripheral surface of the crank pulser 41 cross. Then, the rotational speed NE of the gasoline engine 1 is calculated from the crank angle signal. The teeth 41a of the crank pulser 41 are composed of 34 teeth in which 36 teeth are arranged at regular intervals and two consecutive teeth are removed as a missing tooth part 41b at one location. When the crankshaft 7 rotates, a pulse signal of each tooth 41a, that is, a crank angle signal is output every 10 ° CA (crank angle) as shown in FIG. At the position of the toothless portion 41b, the pulse interval is 30 ° CA, and a reference signal indicating such a toothless portion 41b appears every 360 ° CA. Then, the rotation angle of the crankshaft 7, that is, the crank angle is detected based on the crank angle signal obtained from the teeth 41a and the reference signal obtained from the toothless portion 41b. Incidentally, the number of the teeth 41a and the number of missing teeth of the missing tooth portion 41b can be set appropriately according to the detection resolution of the crank angle and the like.
[0032]
On the other hand, the intake camshaft 17 is provided with a cam pulser 43 that can rotate integrally with the intake camshaft 17, and a cam angle sensor 42 is provided near the cam pulser 43.
[0033]
FIG. 2B shows a configuration and an arrangement diagram of the cam angle sensor 42 and the cam pulser 43. The cam angle sensor 42 outputs a pulse signal each time one protrusion 43a formed on the outer peripheral surface of the cam pulser 43 crosses. The position of the projection 43a is determined so that the pulse signal is output at a predetermined crank angle before the piston of the first cylinder of the gasoline engine 1 reaches the compression top dead center. When the crankshaft 7 rotates, as shown in FIG. 3A, a pulse signal of the protruding portion 43a, that is, a cam angle signal (cylinder discrimination signal) is output from the shaping waveform signal every 720 ° CA. Further, the output interval time T of the cam angle signal output each time the crankshaft 7 rotates 720 ° CA changes according to the engine speed. Thus, in the present embodiment, the engine speed NE, the crank angle CA, and the compression top dead center of the first cylinder are calculated based on the pulse signals output from the crank angle sensor 40 and the cam angle sensor 42.
[0034]
In addition, the gasoline engine 1 is provided with various sensors for detecting an engine operating state. For example, the throttle opening sensor 44 provided near the throttle valve 23 detects the opening TA of the throttle valve 23 (throttle opening TA). An intake air amount QA flowing through the intake passage 20 is detected by an air flow meter 45 provided upstream of the throttle valve 23. The temperature of the cooling water is detected by a water temperature sensor 46 provided in the cylinder block 2.
[0035]
On the other hand, a flywheel 31 which is a flywheel is provided at one end of the crankshaft 7 so as to be integrally rotatable, and a ring gear is provided on an outer peripheral surface of the flywheel 31. A starter motor 60, which is a motor for starting the gasoline engine 1 and is a cranking power source that operates when electric power is supplied from a vehicle-mounted battery, is provided near the ring gear. The output shaft of the starter motor 60 is provided with a pinion gear 61 that meshes with the ring gear. Further, the starter motor 60 is provided with a starter switch 47 for detecting the operation state. The starter switch 47 outputs a starter signal when the ignition switch is operated from the off position to the start position by the driver at the start of the gasoline engine 1 and the starter motor 60 is operating (in the cranking state). Output as "ON". Also, when the start of the gasoline engine 1 is completed (it becomes a complete explosion state) or the start of the gasoline engine 1 fails and the ignition switch is returned from the start position to the ON position, the starter switch 47 The starter signal is output as "OFF".
[0036]
Various controls such as the ignition timing control and the fuel injection timing control of the gasoline engine 1 are performed by a control device (hereinafter, referred to as an ECU) 50. The ECU 50 is mainly composed of a microcomputer having a central processing unit (CPU). For example, the ECU 50 is provided with a read-only memory (ROM) in which various programs, maps, and the like are stored in advance, and a random access memory (RAM) that temporarily stores calculation results of the CPU and the like. The ECU 50 is also provided with a backup RAM, an input interface, an output interface, and the like for storing calculation results, pre-stored data, and the like even after the engine is stopped.
[0037]
Output signals from the crank angle sensor 40 and the cam angle sensor 42 are input to an input interface via a waveform shaping circuit (binarization circuit). Output signals from the throttle opening sensor 44, the air flow meter 45, the water temperature sensor 46, and the like are input to an input interface via an A / D (analog / digital) converter. The state of the starter switch 47 is directly monitored via the input interface. The operating state of the gasoline engine 1 is detected by the sensors 40, 42, 44 to 46, the starter switch 47, and the like.
[0038]
On the other hand, the output interface is connected to the fuel injection valve 35, the ignition coil for applying a high voltage to the ignition plug 11, the actuator 22 of the throttle valve 23, and the like via the corresponding drive circuits and the like. Then, the ECU 50, based on signals from the sensors 40, 42, 44 to 46, the starter switch 47, and the like, according to the control program and control data stored in the ROM, controls the fuel injection valve 35, the ignition coil, and the actuator. 22 and the like are controlled.
[0039]
The ECU 50 executes fuel ignition by the spark plug 11 and fuel injection by the fuel injection valve 35 corresponding to a predetermined crank angle. The detection of the crank angle and the cylinder discrimination are calculated based on the crank angle signal output from the crank angle sensor 40 and the cam angle signal output from the cam angle sensor 42. Here, if noise is superimposed on the output signal from the crank angle sensor 40 or the cam angle sensor 42 or if the output signal is missing, the reliability of the crank angle signal or the cam angle signal is reduced, and an accurate crank angle signal is obtained. Angle detection and cylinder discrimination cannot be performed. In this case, since accurate ignition timing control and fuel injection timing control cannot be performed, in the present embodiment, the presence or absence of abnormality in the crank angle sensor 40 and the cam angle sensor 42 is diagnosed as follows. ing.
[0040]
Hereinafter, abnormality diagnosis processing of the crank angle sensor 40 and the cam angle sensor 42 by the diagnosis method and the diagnosis device for the internal combustion engine according to the present embodiment will be described in detail with reference to FIG.
[0041]
FIG. 4 shows a diagnosis procedure for an aspect of abnormality diagnosis by the diagnosis method according to the present embodiment. In the present embodiment, the abnormality diagnosis process is executed by the ECU 50 when the starter signal is turned on.
[0042]
When this process is started, first, it is determined whether or not the elapsed time since the starter signal was turned “on” is within the abnormality determination period DT (step S110). The abnormality determination period DT is, as shown in FIG. 5, after a predetermined time PT has elapsed since the starter signal was turned “ON” and when the engine speed NE reaches a determination value α described later, The period is set as a period until the engine speed NE increases and reaches a determination value β described later. If the elapsed time does not fall within the abnormality determination period DT (NO in step S110), the process ends.
[0043]
On the other hand, when the elapsed time is within the abnormality determination period DT (YES in step S110), the following processing is continuously performed as the primary determination by the first determination unit.
[0044]
First, while the intake camshaft 17 makes one rotation, in other words, within the output interval time T of the cam angle signal, the number of output times NCR of the crank angle signal output from the crank angle sensor 40 is read (step S120). The number of times of output of the crank angle signal NCR is measured by, for example, providing a counter for counting the number of times of output of the crank angle signal in the ECU 50 and operating the counter in accordance with the output timing of the cam angle signal. Can be.
[0045]
Next, it is determined whether or not the number of times of output of the crank angle signal NCR is equal to the predetermined value NCRP (step S130). This predetermined value NCRP is set to the number of times a crank angle signal is to be output during one rotation of the intake camshaft 17, in other words, two rotations of the crankshaft 7, and in this embodiment, Is 34 × 2 = 68 pulses. If the number of outputs NCR is equal to the predetermined value NCRP (YES in step S130), it is determined that both the crank angle sensor 40 and the cam angle sensor 42 are normal (step S140), and the process ends.
[0046]
On the other hand, if the number of outputs NCR is different from the predetermined value NCRP (NO in step S130), at least one of the crank angle sensor 40 and the cam angle sensor 42 is abnormal, and the second determination is continued. The following processing is performed as the secondary determination by the means, and a sensor having an abnormality is specified.
[0047]
First, based on the following equation (1), the actual engine speed NECAM during cranking is calculated from the output interval time T (seconds) of the cam angle signal shown in FIG. 3 (step S150).
[0048]
Engine rotation speed NECAM = (1 / T) × 60 × 2 (1)
Next, it is determined whether or not the calculated actual engine rotation speed NECAM is a speed that can be taken during cranking of the gasoline engine 1 (step S160). This determination is made based on the following equation (2).
[0049]
Judgment value α ≦ engine speed NECAM ≦ judgment value β (2)
The rotation speed range set by the determination values α and β is a range that can be taken as the engine rotation speed when the gasoline engine 1 is cranked only by the driving force of the starter motor 60. The values α and β are empirically determined in advance by experiments or the like.
[0050]
If the engine speed NECAM falls within the range of the engine speed at the time of cranking (YES in step S160), the cam angle sensor 42 accurately detects the rotation of the intake camshaft 17, and the cam angle sensor 42 is normal. Therefore, it is determined that the reason why the number of times of output of the crank angle signal NCR did not become equal to the predetermined value NCRP in step S130 is that there is an abnormality in the crank angle sensor 40 (step S180), and the present process ends.
[0051]
On the other hand, if the engine rotation speed NECAM is out of the range of the engine rotation speed at the time of cranking (NO in step S160), it is determined that the cam angle sensor 42 is abnormal (step S170), and the process ends. I do.
[0052]
When a sensor that outputs an abnormal signal out of the crank angle sensor 40 and the cam angle sensor 42 is identified in this manner, the determination result may be used, for example, by turning on a warning light in a vehicle cabin. The user can be notified of the abnormality or switched to emergency ignition timing control or fuel injection timing control as fail-safe.
[0053]
As described above, in the present embodiment, first, the crank pulser 41 is configured to output 34 crank angle signals each time the crankshaft 7 makes one rotation. The cam pulser 43 is configured so that one cam angle signal is output every two rotations of the crankshaft 7. Accordingly, when there is no abnormality in the crank angle sensor 40 and the cam angle sensor 42 and the crank angle signal and the cam angle signal are correctly output, the number of times the crank angle signal is output within the output interval time T of the cam angle signal is output. Is 68 times. Therefore, at this time, in step S130 of the primary determination, it is determined that the number of times NCR of outputting the crank angle signal within the output interval time T of the cam angle signal is equal to the predetermined value NCRP, and the crank angle sensor 40 and the cam angle sensor 42 are determined. Are determined to be normal. On the other hand, when noise is superimposed on the cam angle signal and the output interval time T is shortened, or when the crank angle signal is missing and the number of times of output is reduced, the number of times of output of the crank angle signal NCR is reduced. Less than 68 times. When the output interval time T becomes longer due to lack of the cam angle signal, or when the number of outputs of the crank angle signal increases due to noise superimposed on the crank angle signal, the number NCR of output of the crank angle signal becomes 68 times. More than That is, if at least one of the crank angle sensor 40 and the cam angle sensor 42 has an abnormality, the number of times NCR of outputting the crank angle signal within the output interval time T of the cam angle signal is determined by the crank angle sensor 40 and the cam angle sensor 42 is different from the number of times output when all are normal. Therefore, in the above step S130, it is determined that the number of times of output of the crank angle signal NCR is different from the predetermined value NCRP, and it is determined that at least one of the crank angle sensor 40 and the cam angle sensor 42 has an abnormality. You.
[0054]
Further, when it is determined by the primary determination that at least one of the crank angle sensor 40 and the cam angle sensor 42 has an abnormality, the sensor having the abnormality is identified by the secondary determination. Be done.
[0055]
That is, in the above embodiment, the intake camshaft 17 provided with the cam pulsar 43 is drivingly connected to the crankshaft 7 by the timing belt 14. Accordingly, there is a correlation between the output interval time T of the cam angle signal and the engine rotation speed NE, and the engine rotation speed NECAM can be calculated from the output interval time T. Further, the engine speed when the gasoline engine 1 is cranked by the starter motor 60 is a value that can be known in advance through experiments and the like. Therefore, if the cam angle signal is output correctly, the actual engine speed NECAM calculated at the time of cranking should fall within the range of the engine speed at the time of cranking which is determined empirically in advance. Therefore, when it is determined in step S160 that the actual engine speed NECAM calculated from the output interval time T of the cam angle signal is a speed that can be obtained during cranking of the gasoline engine 1, the cam angle sensor 42 is normally operated. Is determined. When it is determined that the cam angle sensor 42 is normal, the result of the determination that at least one of the crank angle sensor 40 and the cam angle sensor 42 is abnormal in the primary determination described above. Is determined to be based on the abnormality of the crank angle sensor 40. On the other hand, if it is determined in step S160 that the actual engine rotation speed NECAM calculated from the output interval time T of the cam angle signal is not a speed that can be taken at the time of cranking of the gasoline engine 1, the cam angle sensor 42 is abnormal. Is determined to have occurred. In the present embodiment, the cam pulser 43 is configured so that a cam angle signal is output once every two rotations of the crankshaft. Therefore, when noise is superimposed on the cam angle signal or when the signal is missing, the engine speed NECAM calculated based on the above equation (1) greatly changes. Therefore, when there is an abnormality in the cam angle sensor 42, the engine rotational speed NECAM is out of the rotational speed range set by the determination values α and β, and the abnormality determination of the cam angle sensor 42 is performed by the secondary determination. Can be performed reliably.
[0056]
As described above, according to the diagnosis method and the diagnosis device for an internal combustion engine according to the present embodiment, the following effects can be obtained.
(1) In the present embodiment, in the primary determination, the number of output times NCR of the crank angle signal within the output interval time T of the cam angle signal, and the same output interval when the crank angle sensor 40 and the cam angle sensor 42 are normal. The number of times of the crank angle signal output within the time T is compared with a set value NCRP. Therefore, the primary determination makes it possible to determine whether any of the crank angle sensor 40 and the cam angle sensor 42 is abnormal.
[0057]
(2) Further, if an abnormality is detected by the primary determination, the engine rotation speed NECAM and the cranking speed determined based on the output of the cam angle sensor 42 at the time of cranking of the gasoline engine 1 are determined by the secondary determination. The engine speed is compared with the engine speed which is empirically determined as the engine speed at the time. More specifically, it is determined whether or not the engine speed NECAM, which can be calculated from the output interval time T of the cam angle signal, is a rotation speed that can be obtained during cranking of the gasoline engine 1. Therefore, by this secondary determination, it is possible to determine whether the cam angle signal is abnormal, in other words, whether the cam angle sensor 42 is abnormal. When it is determined that the cam angle sensor 42 is normal, it is also determined at the same time that the result determined by the primary determination is caused by the abnormality of the crank angle sensor 40.
[0058]
(3) In the secondary determination, the engine rotation speed NECAM when the gasoline engine 1 is in the cranking state is calculated from the output interval time T of the cam angle signal. This engine speed NECAM can be easily calculated, for example, as shown in the above equation (1). Further, it is possible to easily compare the actual engine speed NECAM with the engine speed which is empirically determined as the cranking speed. Therefore, the above-described diagnostic processing can be easily performed.
[0059]
(4) In the secondary determination, the engine rotation speed NECAM is calculated using the cam angle signal. Therefore, when noise is superimposed on the cam angle signal or when the signal is lost, the engine speed NECAM changes greatly, so that the abnormality determination based on the secondary determination can be reliably performed. Become like
[0060]
(5) In the primary determination, when it is determined that both the crank angle sensor 40 and the cam angle sensor 42 are normal, the secondary determination is not performed. Therefore, the diagnostic load when both the crank angle sensor 40 and the cam angle sensor 42 are normal is reduced.
[0061]
The above embodiment can be modified and implemented as follows.
In the above-described embodiment, the abnormality diagnosis processing based on the primary determination is performed when the gasoline engine 1 is cranked. However, the abnormality diagnosis processing based on the primary determination may be performed at any time. For example, during the operation of the engine, abnormality diagnosis based on the primary determination is periodically performed. When it is determined in step S130 of FIG. 4 that the number of output NCR of the crank angle signal is different from the predetermined value NCRP, A flag to the effect is set. After that, when the gasoline engine 1 is started (cranking), the flag is checked. If the flag indicates that the output number NCR of the crank angle signal is different from the predetermined value NCRP, the flag The determination may be performed. Also in this case, effects similar to those of the above embodiment can be obtained.
[0062]
In the secondary determination in the above embodiment, the engine rotation speed NECAM at the time of cranking is calculated from the output interval time T of the cam angle signal, and the engine rotation speed NECAM is obtained by the above-mentioned rotation speed obtained by a prior experiment or the like. The abnormality of the cam angle sensor 42 is determined based on whether or not it is within the range. In addition, the engine speed at which the gasoline engine 1 is cranked is determined by an experiment or the like, and the output interval time of the cam angle signal at the determined engine speed is calculated in advance. Then, the abnormality of the cam angle sensor 42 may be determined by comparing the calculated output interval time with the output interval time T of the actual cam angle signal. Also in this case, effects similar to those of the above embodiment can be obtained.
[0063]
In the above-described embodiment and its modifications, in the secondary determination, the engine speed NECAM is calculated based on the output of the cam angle signal. However, the engine speed is calculated based on the output of the crank angle signal. You may do so. For example, the engine rotation speed at the time of actual cranking is calculated based on the output interval time of the crank angle signal, the time during which the crank angle signal is output a predetermined number of times, or the number of times the crank angle signal is output within the predetermined time. You may make it. Then, based on whether or not the engine speed thus calculated is within the above-described range of the engine speed determined by a previous experiment or the like, whether or not the crank angle signal is abnormal, in other words, the crank angle sensor 40 Can be determined whether or not is abnormal. On the other hand, when it is determined that the crank angle sensor 40 is normal, it is also determined at the same time that the result determined by the primary determination is due to the abnormality of the cam angle sensor 42.
[0064]
In the above-described embodiment, first, it is determined whether or not at least one of the crank angle sensor 40 and the cam angle sensor 42 is abnormal by the primary determination, and when an abnormality is detected by the primary determination. In addition, the secondary determination determines which of the crank angle sensor 40 and the cam angle sensor 42 has an abnormality. However, in the secondary determination from the beginning, the abnormality of the cam angle sensor 42 may be determined using the cam angle signal, and the abnormality of the crank angle sensor 40 may be determined using the crank angle signal. In this case, the primary determination can be omitted.
[0065]
Generally, the engine speed when the gasoline engine 1 is cranked by the starter motor 60 is affected by the voltage applied to the starter motor 60. Therefore, in the diagnosis processing based on the secondary determination, the voltage applied to the starter motor 60 may be monitored, and the above-described diagnosis processing may be performed when the monitored voltage is equal to or higher than a predetermined value. In this case, since the rotation speed of the starter motor 60 is stable, the rotation speed range set by the determination values α and β can be narrowed, and the determination accuracy in the above equation (2) can be maintained higher. become able to.
[0066]
In the above embodiment, the output interval of the cam angle signal is set to 720 ° CA, but this output interval may be set arbitrarily. In short, by setting the predetermined value NCRP according to the output interval time T of the cam angle signal and calculating the engine speed NECAM from the output interval time T, it is possible to obtain the same operation and effect as in the above embodiment. it can.
[0067]
In the above embodiment, the crank pulser 41 has a plurality of teeth 41a formed on the outer peripheral surface thereof for generating pulses at predetermined angles corresponding to the rotation of the output shaft of the internal combustion engine. Was. The cam pulsar 43 was a projection 43a formed on the outer peripheral surface. However, any element can be used as long as it can generate a pulse at each predetermined angle corresponding to the rotation of the output shaft of the internal combustion engine. The effect according to the embodiment is obtained.
[0068]
In the above embodiment, the case where the diagnosis method and the diagnosis device according to the present invention are applied to the gasoline engine 1 has been exemplified. However, the target internal combustion engine is not limited to this gasoline engine 1 at all. The present invention can be similarly applied to a diesel engine and other internal combustion engines, for example, an in-cylinder injection internal combustion engine.
[0069]
In addition, technical ideas that can be grasped from the above-described embodiment or modifications thereof will be described below together with the effects thereof.
(A) Diagnosis of an internal combustion engine for diagnosing abnormality of a crank angle sensor for detecting a rotation speed of a crankshaft of an internal combustion engine and a cam angle sensor for detecting a rotation angle of a camshaft drivingly connected to the crankshaft. The method according to claim 1, wherein the cam angle sensor is based on a comparison between an engine speed determined based on an output of the cam angle sensor during cranking of the internal combustion engine and an engine speed empirically determined as the cranking speed. The engine speed is determined based on the output of the crank angle sensor during cranking of the internal combustion engine, and the engine speed is determined empirically as the engine speed during cranking. And diagnosing whether or not the crank angle sensor is abnormal.
[0070]
With this configuration also, it is possible to easily determine the abnormality of the crank angle sensor and the cam angle sensor.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of an embodiment of a diagnosis method and a diagnosis device for an internal combustion engine according to the present invention.
FIG. 2 is a diagram exemplifying an arrangement configuration of a crank angle sensor and a crank pulser and an arrangement configuration of a cam angle sensor and a cam pulser in the embodiment.
FIG. 3 is a schematic diagram illustrating an output mode of a signal (more precisely, a waveform shaping signal) output from the crank angle sensor and the cam angle sensor in the embodiment.
FIG. 4 is a flowchart showing a processing procedure relating to diagnosis of each sensor according to the embodiment.
FIG. 5 is a time chart schematically showing how the engine speed changes during cranking in the internal combustion engine of the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Gasoline engine, 2 ... Cylinder block, 3 ... Cylinder head, 4 ... Cylinder, 5 ... Piston, 6 ... Connecting rod, 7 ... Crankshaft, 8 ... Combustion chamber, 9 ... Intake port, 10 ... Exhaust port, 11 ... Ignition Plug, 12 ... intake valve, 13 ... exhaust valve, 14 ... timing belt, 15 ... intake side timing pulley, 16 ... exhaust side timing pulley, 17 ... intake camshaft, 18 ... exhaust camshaft, 20 ... intake passage, 22 ... Actuator, 23 ... Throttle valve, 30 ... Exhaust passage, 31 ... Flywheel, 35 ... Fuel injection valve, 40 ... Crank angle sensor, 41 ... Crank pulser, 41a ... Teeth, 41b ... Missing tooth part, 42 ... Cam angle sensor, 43: cam pulser, 43a: protrusion, 44: throttle opening sensor, 45: air flow meter, 46: water temperature sensor, 47: Starter switch, 50 ... control unit (ECU), 60 ... starter motor, 61 ... pinion gears.

Claims (9)

A method of diagnosing an internal combustion engine, which diagnoses whether a crank angle sensor for detecting a rotation speed of a crankshaft of the internal combustion engine and a cam angle sensor for detecting a rotation angle of a camshaft that is drivingly connected to the crankshaft has abnormality.
Based on a comparison between an engine speed determined based on the output of the cam angle sensor during cranking of the internal combustion engine and an engine speed empirically determined as the cranking speed, at least abnormality of the cam angle sensor is determined. A method for diagnosing an internal combustion engine, the method comprising diagnosing the presence or absence of an internal combustion engine. Prior to the diagnosis, it is determined whether the correspondence between the output of the crank angle sensor and the output of the cam angle sensor is normal or abnormal, and the diagnosis is executed only when the correspondence between the outputs is determined to be abnormal. Item 6. The method for diagnosing an internal combustion engine according to Item 1. Upon execution of the diagnosis, the crank angle sensor is determined based on a determination that the engine rotation speed determined based on the output of the cam angle sensor falls within the range of the engine rotation speed empirically determined as the rotation speed during cranking. Diagnosing that there is an abnormality, based on the determination that the engine speed determined based on the output of the cam angle sensor is out of the range of the engine speed empirically determined as the cranking speed. The method for diagnosing an internal combustion engine according to claim 2, wherein it is diagnosed that the cam angle sensor is abnormal. A method of diagnosing an internal combustion engine, which diagnoses whether a crank angle sensor for detecting a rotation speed of a crankshaft of the internal combustion engine and a cam angle sensor for detecting a rotation angle of a camshaft that is drivingly connected to the crankshaft has abnormality.
Based on a comparison between an engine speed determined based on the output of the crank angle sensor during cranking of the internal combustion engine and an engine speed empirically determined as the crank speed during cranking, at least abnormality of the crank angle sensor is determined. A method for diagnosing an internal combustion engine, the method comprising diagnosing the presence or absence of an internal combustion engine. Prior to the diagnosis, it is determined whether the correspondence between the output of the crank angle sensor and the output of the cam angle sensor is normal or abnormal, and the diagnosis is executed only when the correspondence between the outputs is determined to be abnormal. Item 6. The method for diagnosing an internal combustion engine according to Item 4. Upon execution of the diagnosis, the cam angle sensor is determined based on a determination that the engine rotation speed determined based on the output of the crank angle sensor falls within a range of the engine rotation speed empirically determined as the rotation speed during cranking. Diagnosing the abnormality, based on the determination that the engine rotation speed determined based on the output of the crank angle sensor is out of the range of the engine rotation speed empirically determined as the rotation speed at the time of the cranking. 6. The method for diagnosing an internal combustion engine according to claim 5, wherein it is diagnosed that the crank angle sensor is abnormal. In a diagnostic device for an internal combustion engine, which diagnoses the presence or absence of abnormality with respect to a crank angle sensor for detecting a rotation speed of a crankshaft of the internal combustion engine and a cam angle sensor for detecting a rotation angle of a camshaft drivingly connected to the crankshaft,
First determining means for determining whether the correspondence between the output of the crank angle sensor and the output of the cam angle sensor is normal or abnormal;
The engine speed determined based on the output of the cam angle sensor at the time of cranking of the internal combustion engine and the rotation speed at the time of cranking, provided that the first determination means determines that the response is abnormal. An internal combustion engine diagnostic apparatus, comprising: a second determination unit that determines which one of the crank angle sensor and the cam angle sensor is abnormal by comparing an engine rotation speed empirically determined as . In a diagnostic device for an internal combustion engine, which diagnoses the presence or absence of abnormality with respect to a crank angle sensor for detecting a rotation speed of a crankshaft of the internal combustion engine and a cam angle sensor for detecting a rotation angle of a camshaft drivingly connected to the crankshaft,
First determining means for determining whether the correspondence between the output of the crank angle sensor and the output of the cam angle sensor is normal or abnormal;
The engine speed obtained based on the output of the crank angle sensor at the time of cranking of the internal combustion engine and the engine speed at the time of cranking, provided that the first determination means determines that the response is abnormal. An internal combustion engine diagnostic apparatus, comprising: a second determination unit that determines which one of the crank angle sensor and the cam angle sensor is abnormal by comparing an engine rotation speed empirically determined as . 8. The system according to claim 7, wherein the second determination unit monitors a voltage applied to a starter motor that is a cranking power source of the internal combustion engine, and executes the determination on condition that the monitored voltage is equal to or higher than a predetermined value. Or the diagnostic device for an internal combustion engine according to 8.

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