JP2606413B2 - Ring gear sensor abnormality diagnosis device in misfire detection device of internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ring gear provided for detecting the angular velocity in a misfire detecting apparatus for detecting a misfire of an internal combustion engine from a minute change in an angular velocity of a crankshaft. The present invention relates to an abnormality diagnosis device for diagnosing the presence or absence of a sensor abnormality.

2. Description of the Related Art When a misfire occurs in an internal combustion engine, unburned air-fuel mixture is discharged as it is, which not only causes an increase in harmful components in the exhaust gas, but also causes a decrease in output and a decrease in engine stability. Invite.
Therefore, it is easy to determine whether a misfire has occurred in recent years.
For example, there is a demand for a misfire detection device that detects a fire in a normal operation state.

As one of the methods for detecting the misfire, a method of detecting a minute change in the angular velocity of the crankshaft using, for example, an electromagnetic pickup or the like has been considered (for example, Japanese Patent Laid-Open No. 57-188748)
No.).

However, it is actually very difficult to accurately detect minute angular velocity fluctuations due to a misfire. Therefore, focusing on a ring gear for a starter motor fixed to an end of a crankshaft, a ring gear sensor is provided in proximity to the ring gear, and the presence or absence of a misfire is determined based on a change in a required time required to detect a predetermined number of teeth. The applicant has previously proposed such a misfire detection device.

Problems to be Solved by the Invention Meanwhile, in a ring gear in which the starter motor meshes, there is a possibility that teeth may be lost due to long-term use. If a tooth is missing, the output of the ring gear sensor for detecting the number of teeth becomes abnormal, and the final misfire detection becomes inaccurate. In addition, the output itself of the ring gear sensor cannot be obtained due to a disconnection of the harness or the like, and as a result, the operation may be continued without performing the misfire detection.

Means for Solving the Problems Therefore, the present invention diagnoses the presence or absence of an abnormality in the ring gear sensor by using the time required for a predetermined number of teeth measured by the ring gear sensor for misfire detection. . That is, as shown in FIG. 1, a ring gear sensor abnormality diagnostic device in a misfire detection device for an internal combustion engine according to the present invention includes: a reference position detecting means 1 for issuing a reference position signal at a reference crank angle position of each cylinder; A ring gear sensor 2 that is provided close to the ring gear at the end of the crankshaft with which it meshes, and that outputs an output according to the number of passing teeth of the ring gear; and that a predetermined number of teeth have passed through a predetermined phase based on the reference position signal. Counter means 7 for detecting the number of teeth, measuring means 3 for measuring a required time required to detect the predetermined number of teeth, and misfire determining means 4 for determining misfire of the internal combustion engine based on the fluctuation of the required time. In an internal combustion engine misfire detection device, an inter-cylinder elapsed time meter that measures an inter-cylinder elapsed time between a reference position signal of a certain cylinder and a reference position signal of a next cylinder. And means 5, the ratio of the inter-cylinder elapsed time and the required time is configured and a fault determination unit 6 for determining whether or not within a predetermined range.

The required time corresponding to the predetermined number of teeth of the ring gear indicates the angular velocity of the crankshaft, and a misfire state is detected from a change in the required time.

On the other hand, since the reference position signal is also output in synchronization with the rotation of the crankshaft, the inter-cylinder elapsed time from the reference position signal of a certain cylinder to the next reference position signal and the required time by the ring gear sensor 2 are determined. Time is essentially a constant ratio. Therefore, if there is a missing tooth of the ring gear or any abnormality of the ring gear sensor 2 itself, the ratio between the two becomes outside the predetermined range, and the abnormality can be easily detected.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 2 is an explanatory view showing a mechanical structure of one embodiment of the present invention, wherein 11 is an internal combustion engine, 12 is an intake passage, and 13 is an exhaust passage. In this embodiment, a 4-cycle in-line 6-cylinder internal combustion engine will be described as an example.

In the intake passage 12, a fuel injection valve 14 for supplying fuel toward each intake port is provided for each cylinder, and a throttle valve 15 is interposed.The throttle valve 15 is provided upstream of the throttle valve 15. ,
For example, a hot wire type air flow meter for detecting the intake air amount Q
Sixteen are arranged. The throttle valve 15 is provided with a throttle valve opening sensor 17 for detecting the opening TVO.

 Reference numeral 18 denotes a vehicle speed sensor that detects a vehicle speed VSP.

Reference numeral 19 denotes a crank angle sensor provided at the end of the camshaft, inside the distributor, or the like to detect the engine speed Ne and the crank angle position. The crank angle sensor 19 includes a pulse signal (REF signal) for detecting a reference position of each cylinder, for example, a top dead center position, and a unit crank angle (for example, 2 ° C. A) for detecting a rotation angle from the reference position. ) And a pulse signal (POS signal). The REF signal is output at every 120 ° C. for a six-cylinder engine, and is output at a predetermined angle before the top dead center of each cylinder. More specifically, the pulse width of the pulse corresponding to each cylinder is different.
It is possible to detect the compression top dead center position of the cylinder and thereby determine the cylinder of each cylinder (see FIG. 3A). Therefore,
In this embodiment, the REF signal is used as a reference position signal.

On the other hand, a ring gear 21 that can mesh with a starter motor (not shown) is attached to the rear end of the crankshaft 20 together with a flywheel. The teeth of the ring gear 21 are formed at equal intervals, for example, every 6 ° C. A ring gear sensor 22 including an electromagnetic pickup or the like is provided near the ring gear 21. The ring gear sensor 22 forms an ON-OFF pulse signal and outputs an AC current generated by the passage of the teeth of the ring gear 21, thereby obtaining a pulse train as shown in FIG. 3 (b). Can be When the crank angle sensor 19 is provided for a camshaft or the like, the accuracy of the POS signal is affected by the backlash of the valve operating mechanism or the like.
It is difficult to detect angular velocity fluctuation due to misfire from the signal. On the other hand, since the ring gear sensor 22 detects the rotation speed of the ring gear 21 directly connected to the crankshaft 20, it is possible to reliably detect angular velocity fluctuation.

The control unit 23 to which the detection signals of the above-described sensors are input uses a so-called microcomputer system, and controls the air-fuel ratio by the fuel injection valve 14, controls the ignition timing of an ignition system (not shown), and the like. Further, misfire determination based on the detection signal of the ring gear sensor 22 and abnormality diagnosis of the ring gear sensor 22 itself are performed, and when a predetermined misfire or abnormality of the ring gear sensor 22 is detected, an alarm means such as an alarm lamp 24 is activated. At the same time, the abnormal state is stored for inspection and maintenance.

Next, the operation of the above embodiment will be described in detail including determination of misfire.

First, the detection of the angular velocity for each cylinder will be described with reference to FIG. 3. As shown in FIG.
After detecting the REF signal output every time, the ring gear sensor 22
Is started, and when a predetermined number of teeth, for example, P teeth are detected, the control unit 23
A first trigger as shown in FIG. 4C is output by a preset counter (not shown). Furthermore, from now on
When the number of teeth is detected, a preset counter (not shown) outputs a second trigger as shown in FIG. That is, during this time, the crankshaft 20 rotates by the crank angle corresponding to the number of m teeth. The timer in the control unit 23 measures the required time T during the period from the first trigger to the second trigger.

The measurement of the required time T is repeatedly performed every time the REF signal is output, that is, every 120 ° C. A. And the number of cylinders is N
(N + 1) data is always stored as (N = 6 in this embodiment). More specifically, the data up to T (N + 1) is stored in a sequentially updated manner, with the latest data being T1 and the previous data being T2, and a misfire determination is made based on these, as described later. .

The phase for measuring the required time T should, of course, be set by selecting a period in which the angular velocity fluctuation due to misfire appears most remarkably. In this way, by focusing only on the phase within a certain range, there is no influence even if there is a change in angular velocity due to friction or the like in other periods.

In parallel with the measurement of the required time T,
The time from the REF signal to the REF signal of the next ignition cylinder, that is, the inter-cylinder elapsed time TREF is sequentially measured.

Next, FIG. 4 is a main flowchart showing a specific processing flow executed in the control unit 23. The processing shown in FIG.
At the end of the detection of the number of m teeth, ie, in synchronization with the second trigger.

First, a flag FT indicating that the detection of the number of m teeth, that is, the measurement of the required time T described above is completed before the generation of the next REF signal, is set to "1" (step 1). Next, it is determined whether or not various conditions are within the diagnostic region where misfire can be determined (step 2), and the process proceeds to step 4 and subsequent steps only when the condition is within the diagnostic region. If it is out of the diagnosis area, the reading of the required time T is stopped (step 3), and TRAVMX described later is used.
Are cleared (step 14). The determination as to whether or not it is within the diagnostic region is basically a determination as to whether or not there is another factor such as a change in the angular velocity of the engine, and various methods can be considered. An example is shown in FIG. That is, the change amount ΔVSP of the vehicle speed VSP is equal to or smaller than the predetermined value ΔVSP1 (step 21), and the change amount ΔT of the throttle valve opening TVO is set.
VO is less than or equal to a predetermined value ΔTVO1 (step 22), the starter switch is OFF (step 23), and the electrical load is constant, that is, not immediately after the ON / OFF change of the headlight switch (step 22). 24) that the power steering load is constant, that is, the power steering operation is not being performed (step 25), that the engine speed Ne is substantially constant, that is, that the engine speed Ne is within a predetermined range of Ne1 to Ne2 (step 26);
The load of the engine, for example, that the basic fuel injection amount Tp is substantially constant, that is, within a predetermined range of Tp1 to Tp2 (step 27) is set as a diagnosis condition, and when all of these conditions are satisfied, it is set as a diagnosis region. (Step 29) If any one of the conditions is not satisfied, it is determined to be out of the diagnostic region (Step 29).
28). If it is determined in the above-described processing that the area is within the diagnostic area, the process proceeds to step 4 and the required time T described above is read.

Then, the roughness degree RO is sequentially calculated based on the measured required time T, specifically, the data of T1 to T (N + 1) held at that time (step 5).

This roughness degree RO is obtained by calculating the deviation of the required time T from the required time T
Divided by the average of, for example, Is required. This example focuses on T (N / 2) which is the center point of the data of T1 to T (N + 1).
T (N +) one cycle before (before 720 ° C A) of the same cylinder as 1
By using 1), it is possible to reduce the influence of friction or the like that occurs each time at a specific position.

 Note that T (N / 2 + 1) -T (N / 2) and the like can be used as the numerator of the above formula.

 Alternatively, T (N / 2) or {T1 + T2... T (N / 2)} × 2 / N may be used as the denominator.

Since the above calculation of the roughness degree RO is performed in synchronization with the second trigger following the REF signal every time the required time T is measured, that is, every time the REF signal is output, the calculation is performed on the REF signal of the cylinder number n. Roughness degree RO for n cylinders
(N). Therefore, the roughness degree RO (n) of each cylinder is sequentially obtained according to the ignition order.

Here, the roughness degree RO is 0 assuming that there is no angular velocity fluctuation. If there is a misfire, the roughness degree RO of a certain cylinder corresponding to the misfire indicates a negative value, and the roughness degree RO of another cylinder indicates a relatively positive value. In addition, roughness degree RO
The cylinder number n in (n) does not always match the misfiring cylinder.

Next, a moving average TRAVLU of the absolute value is calculated using the roughness degree RO (n). That is, Is calculated every time the REF signal is measured, that is, every time the required time T is measured (step 6).

In addition, the above TRAVLU is set to the past maximum value during the data collection period.
Compare with TRAVMX, and if it exceeds, update the memory content as a new maximum value TRAMMX (step 7). This is the final result of one data collection period
This indicates the maximum value of TRAVLU.

Then, in step 8, an index FU (n) indicating the positive / negative regularity of each cylinder n is calculated. This is FU (1)-FU (N)
Are indicated for each cylinder by N counters. If the roughness degree RO (n) of a certain cylinder n is positive, FU (n)
Is incremented, and if negative, FU (n) is decremented. Therefore, if misfire repeatedly occurs in a certain cylinder n, the index FU (n) of that cylinder n greatly decreases to the negative side.

Next, in step 9, abnormality diagnosis of the ring gear sensor 22 is performed. This will be described later.

In step 10, the moving average TR obtained in step 6 above
The AVLU is compared with the reference value TRAVCO. If the AVLU is equal to or larger than the reference value, the value of the first parameter MMF1 is incremented (step 11). The above reference value TRAVCO is the engine speed Ne.
Alternatively, it is given as a moving average of a reference value COMPL that is sequentially looked up from a map of the engine speed Ne and the basic fuel injection amount Tp.

Since TRAVLU is the average of the absolute values of the roughness degree RO as described above, the first parameter MMF1 is related to the frequency of angular velocity fluctuation of a certain level or more for the entire engine.

In step 12, it is determined whether or not a predetermined data collection period has elapsed. If the data collection period has elapsed, the process proceeds to step 13 to perform a failure determination. The data collection period is defined by time or crank angle, and for example, about 2 to 3 seconds is sufficient. Therefore,
Until the predetermined data collection period elapses, the above-described processing of steps 4 to 11 is repeated, and the calculation of TRAVLU and the like are performed. Then, after performing the failure determination, TRAV
MX and the like are cleared to prepare for the next determination (step 14).

FIG. 8 shows details of the failure determination in step 13 described above. In step 51, a second parameter MMF2 and a third parameter MMF3 are calculated.

The second parameter MMF2 is obtained as MMF2 = TRAVMX / TRAVCO using TRAVMX, which is the maximum value of TRAVLU during the data collection period, and the above-described reference value TRAVCO. The value at the end of data collection is used for TRAVCO. The second parameter MMF2 indicates whether a large angular velocity fluctuation has occurred.

The third parameter MMF3 is the sum of all cylinders of the absolute value of the index FU (n) indicating the above-mentioned positive / negative regularity of each cylinder, that is, MMF3 = | FU (1) | + | FU (2) | ... + | FU (N). Therefore, if the angular velocity decreases or increases in the same cylinder a plurality of times with the same tendency, the third parameter MMF3 increases. If the decrease or increase in the angular velocity appears at random, the value of the third parameter MMF3 does not increase so much.

In step 52, the value of the first parameter MMF1 counted in step 11 described above is compared with a reference value JMF1. If the value is less than the reference value JMF1, the process proceeds to step 53, and the second
The value of the parameter MMF2 is compared with the reference value JMF2. If the value is less than the reference value JMF2, the process proceeds to step 59, where it is determined that "normal", that is, there is almost no misfire. Meanwhile, step 53
If the value of the second parameter MMF2 is equal to or greater than the reference value JMF2, it means that although the angular velocity fluctuations are small as a whole engine, but large angular velocity fluctuations sometimes appear, the process proceeds to step 60, and a low-frequency misfire occurs. Judge as the state.

If the first parameter MMF1 is equal to or more than the reference value JMF1 in step 52, it means that the angular velocity fluctuation occurs frequently in the entire engine, so the third parameter MMF3 is changed to the first reference value JMF3H and the second reference value JMF3H. JMF3L (however, JMF3H> JMF3L)
Are sequentially compared (steps 54 and 55). In the case of JMF3H or more, it means that the decrease or increase of the angular velocity repeatedly appears in the same cylinder with the same tendency as described above, and therefore, it is determined that the frequent misfire of one specific cylinder has occurred (step 56) And the misfiring cylinder is determined (step 57). The misfiring cylinder can be determined based on the index FU (n). In the present embodiment, the ignition cylinder immediately before the cylinder n having the smallest FU (n) corresponds to the misfiring cylinder.

If the third parameter MMF3 is less than JMF3H and less than JMF3L, it means that large angular velocity fluctuations appear frequently and randomly, so that it is determined that a frequent misfire state of a plurality of cylinders has occurred (step 58).

Through the above processing, a detailed determination of the misfire state can be made. When it is determined that a misfire has occurred, the alarm lamp 24 is turned on, and the state of the misfire is stored in the memory.

Next, the flowchart of FIG.
The details of the processing of the sensor diagnosis I of FIG. This is mainly for detecting missing teeth of the ring gear 21. In step 31, the ratio (T / TREF) between the measured required time T and the immediately preceding inter-cylinder elapsed time TREF is obtained, and this is determined as a predetermined value. It is determined whether or not the range is between the lower limit L and the upper limit H. The ratio (T / TREF) is always constant if there is no tooth loss or abnormal output of the ring gear sensor 22 due to any cause.

If the ratio (T / TREF) is out of the range of L to H, the counter CNG is incremented and the counter CN is reset to 0 (step 35). Then, the value of the counter CNG is compared with a predetermined reference value CJNG (step 36). If the value is equal to or larger than the reference value CJNG, the ring gear sensor 22 is abnormal (including a missing tooth as described above). It is determined that there is (Step 37).

If the above ratio (T / TREF) is within the predetermined range, the counter CN is incremented (step 33). When the counter CN reaches a predetermined value, for example, a value N equal to the number of cylinders, the counter CNG is reset. (Step 3
Four). Therefore, erroneous determination due to noise or the like which is not essentially abnormal is prevented.

The flowchart of FIG.
This process is performed to cope with a case where no output is obtained from the CPU. This process is executed in synchronization with the REF signal of each cylinder. That is, in step 41, it is determined whether or not the flag FT is "1" when the REF signal is generated.
Before the generation of the REF signal, it is determined whether the detection of the number of m teeth is completed for the previous cylinder. This flag FT is
The signal is cleared each time a signal is generated (step 48). If the count of the number of teeth does not proceed smoothly due to some abnormality, the FT
= 0.

If the flag FT is "0", the counter CRGNG is incremented and the counter CN 'is incremented.
Is reset to 0 (step 45). Then, the value of the above-mentioned counter CRGNG is compared with a predetermined reference value CJRGNG (step 46), and if it exceeds the reference value CJRGNG, it is determined that the ring gear sensor 22 is abnormal (step 47).

If the flag FT is "1", the counter C
N 'is incremented (step 42), and when this reaches a predetermined value, for example, a value N equal to the number of cylinders, the counter CR is incremented.
GNG is reset (step 44). Accordingly, erroneous determination due to noise or the like is prevented as in the processing of the sensor diagnosis I in FIG.

When it is determined that the ring gear sensor 22 is abnormal as described above, a notification is made by, for example, blinking of the alarm lamp 24, and the abnormality is stored in the memory.

The embodiment of the present invention has been described above. However, the specific method of misfire determination is not necessarily limited to the above embodiment, and various changes can be made.

As is apparent from the above description, the apparatus for diagnosing abnormality of a ring gear sensor of an internal combustion engine according to the present invention determines a required time corresponding to a predetermined number of teeth measured for misfire determination between cylinders between reference position signals. Diagnosis of the presence or absence of an abnormality is compared with the elapsed time, so that an abnormality of the ring gear sensor can be easily detected without adding a new sensor or counter, and for example, a misfire caused by a missing tooth of the ring gear can be detected. Misjudgment can be prevented beforehand.

[Brief description of the drawings]

FIG. 1 is a claim correspondence diagram showing a configuration of the present invention, FIG. 2 is a configuration explanatory diagram showing a mechanical configuration of an embodiment of the present invention,
FIG. 3 is a time chart for explaining the operation of this embodiment, and FIGS. 4, 5, 6, 7, and 8 are flowcharts showing an example of the processing in this embodiment. 1... Reference position detecting means 2... Ring gear sensor 3
... Required time measuring means, 4... Misfire determining means, 5... Inter-cylinder elapsed time measuring means, 6.

Claims (1)

(57) [Claims] A reference position detecting means for generating a reference position signal at a reference crank angle position of each cylinder, and a ring gear at an end of a crankshaft meshed with a starter motor, provided near the ring gear.
A ring gear sensor for outputting an output corresponding to the number of teeth of the ring gear; counter means for detecting passage of a predetermined number of teeth from a predetermined phase with reference to the reference position signal; In a misfire detection device for an internal combustion engine, comprising: a measurement unit for measuring time, and a misfire determination unit for determining misfire of the internal combustion engine based on the fluctuation of the required time, a reference position signal of a certain cylinder and a next cylinder Inter-cylinder elapsed time measuring means for measuring the inter-cylinder elapsed time between the reference position signal, and abnormality determining means for determining whether a ratio of the inter-cylinder elapsed time to the required time is within a predetermined range. A ring gear sensor abnormality diagnosis device in a misfire detection device for an internal combustion engine provided.