JP6394447B2 - Crank angle detector - Google Patents

Description

  The present invention relates to a crank angle detection device that detects a rotation angle of a crankshaft of an internal combustion engine.

2. Description of the Related Art Conventionally, as a crank angle detection device, a device including a crank pulser described below, a crank sensor, a missing tooth detection unit, and a CA generation unit is known.
The crank pulser rotates in synchronization with the crankshaft, and has a plurality of teeth provided on the outer periphery at equal crank angle intervals and a missing tooth portion in which teeth are missing at a predetermined crank angle.
The crank sensor detects the teeth of the crank pulser and outputs a pulse signal.
The missing tooth detection means detects the missing tooth part based on the pulse signal from the crank sensor.
The CA generation means generates a crank angle signal by counting the number of changes in the level of the pulse signal from the crank sensor from the time when the missing tooth detection means detects the missing tooth portion.

By the way, in order to accurately acquire the crank angle signal, it is required to accurately detect a missing tooth portion that becomes a reference when the crank angle signal is counted as the crankshaft rotates.
The missing tooth portion is detected based on the pulse width and pulse ratio of the pulse signal output from the crank sensor (ratio of the pulse widths of two consecutive pulses). For example, the determination is made based on whether or not the pulse ratio accompanying the rotation has reached a predetermined value or more.

However, when the engine speed changes greatly, such as when the engine is started or stopped, an increase in the pulse ratio may be detected at a position that is not a missing tooth portion, and may be erroneously detected as a missing tooth portion. .
Also, due to noise, reverse rotation, sudden gear change, engine stall with gears connected etc., although it is not actually a missing tooth part, it is a missing tooth part in the judgment by the pulse ratio of the pulse signal It may be detected.

Therefore, in order to avoid such erroneous detection of the missing tooth portion, there is a method of using the output of the cam sensor that detects the rotational position of the camshaft.
The crank angle detection device described in Patent Document 1 determines erroneous detection of a missing tooth portion based on whether or not the input order of pulses from a cam sensor and pulses from a crank sensor is a specific pattern.

  However, with such a method, in the case of an internal combustion engine in which the rotational phase of the camshaft relative to the crankshaft can be changed, if the rotational phase changes, the input order of the pulses from the cam sensor and the pulses from the crank sensor will change, resulting in lack of It cannot be used to determine whether or not the tooth part is erroneously detected.

JP-A-6-307280

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a missing tooth portion in a crank angle detection device applied to an internal combustion engine capable of changing the rotational phase of a camshaft with respect to the crankshaft. This is to make it possible to determine erroneous detection.

  The crank angle detection device of the present invention includes a first rotating body, a first sensor, a missing tooth detection unit, a CA generation unit, and an erroneous detection determination unit described below.

The first rotating body rotates in synchronization with the crankshaft of the internal combustion engine, and has a plurality of teeth on the outer periphery at equal crank angle intervals and a missing tooth portion in which the teeth are missing at a predetermined crank angle.
The first sensor detects the teeth of the first rotating body and outputs a pulse signal.

The missing tooth detection means detects the missing tooth portion based on the pulse signal from the first sensor.
The CA generation means generates a crank angle signal by counting the number of times the level of the pulse signal from the first sensor has changed since the missing tooth detection means has detected the missing tooth portion.
The erroneous detection determination means determines whether or not the detection of the missing tooth portion by the missing tooth detection means is an erroneous detection.

The crank angle detection device is applied to an internal combustion engine that can change the rotational phase of the camshaft relative to the crankshaft.
A second rotating body, a second sensor, specific tooth detection means, phase determination means, storage means, and reading means described below are provided.

The second rotating body rotates in synchronization with the camshaft and has at least one tooth on the outer periphery.
The second sensor detects the teeth of the second rotating body and outputs a pulse signal.
The specific tooth detecting means detects a specific tooth among the teeth formed on the second rotating body based on the pulse signal from the second sensor.

The phase determining means determines the rotational phase of the camshaft relative to the crankshaft.
The storage means stores in advance a normal value of the difference between the crank angle at the timing of detecting the specific tooth and the crank angle at the timing of detecting the missing tooth portion for each rotation phase.
Reading means reads the normal value in the thus discriminated rotational phase phase determination means from the storage means.

  Then, the erroneous detection determination means of the present invention calculates the difference between the crank angle at the timing of detecting the specific tooth and the crank angle at the timing of detecting the missing tooth portion, and the normality from which the difference is read out is calculated. If it does not match the value, it is determined as a false detection.

  ADVANTAGE OF THE INVENTION According to this invention, in the crank angle detection apparatus applied to the internal combustion engine which can change the rotational phase of the camshaft with respect to a crankshaft, it becomes possible to determine the erroneous detection of a missing tooth part.

It is a whole block diagram of a crank angle detection apparatus (example). It is a whole block diagram of a crank angle detection apparatus (example). 6 is a timing chart of a crank angle, a crank counter, a crank pulse, and a cam pulse (Example). It is a flowchart of a missing tooth false detection (Example).

  The mode for carrying out the present invention will be described in detail with reference to the following examples.

[Configuration of Example]
The crank angle detection apparatus 1 of an Example is demonstrated using FIGS.
The crank angle detection device 1 is a device that outputs information on the rotational position of the crankshaft 3 of the internal combustion engine 2 as a crank angle signal.
As shown in FIG. 2, the internal combustion engine 2 includes a crankshaft 3 and a camshaft 5 to which driving force is transmitted from the crankshaft 3 by a belt 4 or the like. The crankshaft 3 is a drive shaft and the camshaft 5 is a driven shaft, and the camshaft 5 rotates as the crankshaft 3 rotates.

The internal combustion engine 2 also includes a variable valve timing mechanism 6 that can change the rotational phase of the camshaft 5 relative to the crankshaft 3 (hereinafter referred to as the VCT phase).
The variable valve timing mechanism 6 changes the relative rotation phase between the crankshaft 3 and the camshaft 5 and has a known structure. That is, the phase can be changed to the advance side and the retard side with respect to a predetermined reference position. For example, when the rotational phase of the camshaft 5 that drives an intake valve (not shown) is varied, the opening / closing timing of the intake valve can be advanced or retarded.

  The variable valve timing mechanism 6 receives a command signal transmitted from the ECU 8, and changes the VCT phase to the advance side or the retard side based on this signal.

  The crank angle detection device 1 includes a crank pulser 10 (first rotating body), a crank sensor 11 (first sensor), a cam pulser 14 (second rotating body), a cam sensor 15 (second sensor), and missing tooth detection described below. Means 18, CA generation means 19, erroneous detection determination means 21, specific tooth detection means 22, phase determination means 25, storage means 26, reading means 27, and the like.

The crank pulser 10 is a disk that rotates in synchronization with the crankshaft 3, and is fixed to one end in the axial direction of the crankshaft 3, for example, coaxially with the crankshaft 3 (see FIG. 2).
The crank pulser 10 has a plurality of teeth 10a on the outer periphery at equal crank angle intervals, and has a missing tooth portion 10b in which the teeth 10a are missing at a predetermined crank angle.

The missing tooth portion 10 b is a portion that forms a reference position for the rotational position of the crankshaft 3.
The missing tooth portion 10b is a region where the teeth 10a arranged at equal intervals are missing, and the portion where the extra teeth are provided is also a portion where there are no equally spaced teeth, and therefore falls within the category. And

The crank sensor 11 detects the teeth 10a of the crank pulser 10 and outputs a pulse signal (crank pulse).
The crank sensor 11 is fixed at a position facing the outer peripheral surface of the crank pulser 10 so as not to rotate relative to the crank pulser 10.
Then, the rotation of the crank pulser 10 detects the tooth 10a passing in front of its own detection unit and outputs a pulse signal.
In the missing tooth portion 10b, the pulse width is longer than that in a region where the teeth 10a are provided at equal intervals.

The cam pulser 14 is a disk that rotates in synchronization with the camshaft 5, and is fixed coaxially with the camshaft 5 at one axial end of the camshaft 5, for example (see FIG. 2).
The cam pulser 14 has one tooth 14a (hereinafter referred to as a specific tooth 14a) on the outer periphery.

The cam sensor 15 detects the specific tooth 14a of the cam pulser 14 and outputs a pulse signal (cam pulse).
The cam sensor 15 is fixed at a position facing the outer peripheral surface of the cam pulser 14 so as not to rotate relative to the cam pulser 14.
And the specific tooth | gear 14a which passes the front of an own detection part by rotation of the cam pulser 14 is detected, and a pulse signal is output.

In this embodiment, the ECU 8 includes the functions of the missing tooth detection means 18, the CA generation means 19, the erroneous detection determination means 21, the specific tooth detection means 22, the phase determination means 25, the storage means 26, and the reading means 27. Has been.
The ECU 8 has functions such as a CPU for performing control processing and arithmetic processing, a storage device (memory such as ROM and RAM) for storing various programs and various data, an input circuit (input unit), an output circuit (output unit), and the like. A microcomputer having a known structure including and including is included.

The missing tooth detection means 18 detects the missing tooth portion 10 b based on the pulse signal from the crank sensor 11.
For example, when a signal pattern having a pulse ratio (ratio of pulse widths of two consecutive pulses) greater than or equal to a predetermined value appears in the pulse signal from the crank sensor 11, an end edge of the signal pattern (in this embodiment, a rising signal) ) Is detected, the missing tooth flag is turned on because the missing tooth portion 10b is detected.

The CA generation means 19 generates a crank angle signal by counting the number of crank pulse level changes from the time when the missing tooth detection means 18 detects the missing tooth portion 10b (for example, when the missing tooth flag is turned ON). To do.
That is, as shown in FIG. 3, for example, the crank counter value is added for each level change. When the crankshaft 3 rotates once, the crank counter value becomes 360 ° CA. However, since the missing tooth portion 10b is detected here, it is reset to 0 ° CA.

In the present embodiment, since the internal combustion engine has four cylinders, the camshaft 5 rotates once by two rotations of the crankshaft 3. Therefore, the crank angle for one cycle is 720 ° CA.
The crank position at which the crank counter value starts in one cycle depends on the relationship between the position where the missing tooth portion 10b is detected and the position from the top dead center at that time.
For example, in the example shown in FIG. 3, the crank counter value starts at 60 ° CA before the top dead center with respect to the top dead center (# 1 TDC, # 4 TDC) of the first cylinder and the fourth cylinder.

  If the missing tooth detection of the missing tooth detection means 18 is normal, as shown in FIG. 3, it is accurate for the rotation of the crankshaft 3 until the next missing tooth portion 10b is detected from the previous missing tooth portion 10b. A crank angle signal can be generated. That is, the crank angle can be detected.

  However, if the missing tooth detection of the missing tooth detection means 18 is erroneous detection, for example, in the case of the present embodiment, the crank counter value is reset even though it is not the rotational position of 60 ° CA before top dead center. , The position is detected to be 60 ° CA before top dead center.

The erroneous detection determination means 21 determines whether or not the detection of the missing tooth portion 10b by the missing tooth detection means 18 is an erroneous detection.
The erroneous detection determination means 21 of the present embodiment takes into account the VCT phase at the timing at which the missing tooth portion 10b is detected, and the crank angle at the timing at which the specific tooth 14a is detected and the timing at which the missing tooth portion 10b is detected. It is determined whether or not there is a false detection based on the difference from the crank angle (angle difference d). Hereinafter, a configuration necessary for realizing this erroneous detection and a flow of control will be described.

  The crank angle detection device 1 includes specific tooth detection means 22, phase determination means 25, storage means 26, and reading means 27.

The specific tooth detection unit 22 detects the specific tooth 14 a formed on the cam pulser 14 based on the pulse signal from the cam sensor 15.
In the present embodiment, one tooth is provided so as to form one pulse every half circumference, and this tooth is the specific tooth 14a.
For example, when the cam sensor 15 detects a rising edge of a pulse corresponding to the specific tooth 14a, the specific tooth detection unit 22 sets the specific tooth flag to ON because the specific tooth 14a is detected.

The phase discrimination means 25 discriminates the VCT phase.
In this embodiment, the current VCT phase is determined based on a command signal to the variable valve timing mechanism 6 immediately before the missing tooth detection.
Note that the VCT phase may be determined based on the state of the actuator (hydraulic actuator, electronic actuator, etc.) for changing the VCT phase in the variable valve timing mechanism 6.
Further, when missing tooth detection is normally performed in the previous cycle and there is no command signal for changing the VCT phase by the current cycle, based on the output signal from the crank angle detection device 1 in the previous cycle. It may be determined.

The storage means 26 stores a normal value ds of the angle difference d in advance for each VCT phase.
In this embodiment, during the idling operation in which the internal combustion engine is assumed to be in a stable rotational state, the angle difference d is learned during normal crank angle detection, and the learned value is stored as a normal value ds. doing.

Specifically, the ECU 8 also has a function as a normal value learning unit (not shown), and when the normal value learning unit satisfies a predetermined operation condition (for example, in an idle operation state), Based on the outputs from the missing tooth detection means 18, the specific tooth detection means 22 and the CA generation means 19, the angle difference d is calculated.
The angle difference d is calculated every cycle. The angle difference d is calculated over a plurality of cycles, and the mode value (which may be an average value or a median value) of the plurality of data is calculated.

Then, the VCT phase when this learning is performed is grasped, and the calculated mode value is stored in the storage means 26 as the normal value ds in this VCT phase.
Note that the correlation between the normal value ds and the VCT phase may be stored in advance by MAP or a mathematical formula regardless of learning.

Reading means 27 reads the normal value ds of the phase discriminating means 25 thus discriminated VCT phase from the storage means 26.

  Then, the erroneous detection determination means 21 calculates the angle difference d, and determines that it is erroneous detection when this value does not coincide with the read normal value ds.

The CA generation unit 19 adds a crank counter from the timing at which the missing tooth portion 10b is detected even if the missing tooth detection is an erroneous detection, and generates a crank angle signal. This signal is called a temporary crank angle signal (also called a crank angle signal of the current cycle).
The erroneous detection determination means 21 calculates the crank angle at the timing when the missing tooth portion 10b is detected and the crank angle at the timing when the specific tooth 14a is detected based on this temporary crank angle signal.

  For example, when the VCT phase is phase A, the state in which the specific tooth 14a is detected after the missing tooth portion 10b is detected is a normal state (see FIG. 3). For this reason, both the crank angle when the missing tooth portion 10b is detected and the crank angle when the specific tooth 14a is detected are grasped based on the temporary crank angle signal. Therefore, the angle difference d is also calculated based on the temporary crank angle signal.

  If this angle difference d is equal to the normal value ds at the time of phase A, it is determined that the temporary crank angle signal is a normal signal. However, when the angle difference d is different from the normal value ds at the phase A, it is determined that the missing tooth is erroneously detected, and it is determined that the temporary crank angle signal is an abnormal signal.

In the present embodiment, when the VCT phase is the phase B, the state where the missing tooth portion 10b is detected after the specific tooth 14a is detected is a normal state.
In this case, the crank angle at the time when the specific tooth 14a is detected is grasped based on the crank angle signal in the previous cycle. Then, it is normal that the missing tooth portion 10b appears after the normal value ds from the crank angle at which the specific tooth 14a appears, but when it appears before or after that, it is determined that the missing tooth is erroneously detected.

Next, the crank angle detection flow including the erroneous detection detection described above will be described with reference to the flowchart of FIG.
First, in step S1, the missing tooth detection means detects the missing tooth portion 10b.
Next, in step S2, crank counting is started from the point of time when missing teeth are detected, and a crank angle signal (temporary crank angle signal, crank angle signal of the current cycle) is generated.
Next, in step S3, the VCT phase is discriminated by the phase discriminating means 25.

Thereafter, the process proceeds to step S4, and the normal value ds corresponding to the determined VCT phase is read from the storage unit.
In step S5, the crank angle difference d between the crankshaft position at the timing at which the missing tooth portion is detected and the crankshaft position at the timing at which the specific tooth is detected is calculated based on the crank angle signal. .
Note that either step S4 or S5 may be first.

In step S6, it is determined whether or not the crank angle difference d is a normal value.
If it is a normal value, it will progress to step S7 and will determine with missing tooth detection being normal.
If it is not a normal value, it will progress to step S8 and will determine with missing tooth detection being a false detection.

If it is determined that the missing tooth detection is normal, the generated current crank angle signal is used as it is.
If it is determined that the missing tooth detection is abnormal, the generated crank angle signal is not adopted. For example, the crank angle signal of the previous cycle is adopted.

[Effects of this embodiment]
According to the present embodiment, in the crank angle detection device 1 applied to the internal combustion engine in which the rotation phase of the camshaft 5 relative to the crankshaft 3 can be changed, it is possible to determine erroneous detection of the missing tooth portion 10b.

That is, even if the rotation phase changes, a normal value is stored for each rotation phase, so if the rotation phase is grasped, it is possible to determine erroneous detection of the missing tooth portion 10b by comparison with the normal value. is there.
As a result, in the case of erroneous detection of missing teeth, it is possible to perform processing such as non-adoption of the crank angle signal or correction of the crank angle signal, so that highly accurate crank angle detection can be performed.

In the present embodiment, a learning value obtained by learning performed during idling is stored as a normal value.
For this reason, the normal value can be made to follow the actual mechanical angle change due to aging degradation or the like, rather than the case where it is stored in advance as a constant.
It is also possible to apply the crank angle detection device 1 uniformly to internal combustion engines having various changes in the VCT phase.

[Modification]
In the embodiment, the rotational phase of the camshaft 5 with respect to the crankshaft 3 can be changed by the variable valve timing mechanism 6, but “the rotational phase of the camshaft 5 with respect to the crankshaft 3 can be changed” means, for example, deterioration over time. It is also assumed that a state in which the rotation phase can be changed is included.

  In the embodiment, the cam pulser 14 has only one tooth, and the tooth is the specific tooth 14a. However, the tooth has a plurality of teeth, and one of the teeth may be the specific tooth 14a.

  DESCRIPTION OF SYMBOLS 1 Crank angle detection apparatus, 2 Internal combustion engine, 3 Crankshaft, 5 Camshaft, 10 1st rotary body, 10a tooth, 10b Missing tooth part, 11 1st sensor, 14 2nd rotary body, 14a Specific tooth, 15 2nd Sensor, 18 missing tooth detection means, 19 CA generation means, 21 erroneous detection determination means, 22 specific tooth detection means, 25 phase determination means, 26 storage means, 27 reading means

Claims (3)

Rotating in synchronism with the crankshaft (3) of the internal combustion engine (2), a plurality of teeth (10a) are provided on the outer periphery at equal crank angle intervals, and a missing tooth portion (with no teeth at a predetermined crank angle) ( A first rotating body (10) having 10b);
A first sensor (11) for detecting a tooth (10a) of the first rotating body (10) and outputting a pulse signal;
A missing tooth detection means (18) for detecting the missing tooth portion (10b) based on a pulse signal from the first sensor (11);
CA that generates a crank angle signal by counting the number of changes in level of the pulse signal from the first sensor (11) from the timing when the missing tooth detection means (18) detects the missing tooth portion (10b). Generating means (19);
A crank angle detection device comprising: a false detection determination means (21) for determining whether or not the detection of the missing tooth portion (10b) by the missing tooth detection means (18) is a false detection,
This crank angle detection device is applied to an internal combustion engine in which the rotational phase of the camshaft (5) relative to the crankshaft (3) can be changed,
A second rotating body (14) rotating in synchronization with the camshaft (5) and having at least one tooth on the outer periphery;
A second sensor (15) for detecting a tooth of the second rotating body (14) and outputting a pulse signal;
Specific tooth detection means (22) for detecting a specific tooth (14a) of the teeth formed on the second rotating body (14) based on a pulse signal from the second sensor (15);
Phase discriminating means for discriminating the rotational phase of the camshaft (5) relative to the crankshaft (3);
The normal value of the difference between the crank angle at the timing of detecting the specific tooth (14a) and the crank angle at the timing of detecting the missing tooth portion (10b) is stored in advance for each rotation phase. Storage means (26);
And a reading means (27) for reading the normal value of said phase discriminating means (25) to thus discriminated the rotational phase from the storage means (26),
The erroneous detection determination means (21)
The difference between the crank angle at the timing of detecting the specific tooth (14a) and the crank angle at the timing of detecting the missing tooth portion (10b) is calculated, and this difference is set to the read normal value. A crank angle detection device, characterized in that, if they do not coincide, it is determined that there is a false detection. The crank angle detection device according to claim 1,
The internal combustion engine (2) includes a variable valve timing mechanism. The crank angle detection device according to claim 1,
The storage means (26)
Storing the relative position between the position of the missing tooth portion (10b) and the position of the specific tooth (14a) detected when the internal combustion engine (2) is in an idle operation state as the normal value. A crank angle detection device.

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