JP2008169697A - Cam phase detector for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect a rotational phase of a camshaft to a crankshaft in a short period even in a low rotation area. <P>SOLUTION: This cam phase detecting device has a sensor for outputting a unit cam angle signal CAM with every unit angle, and a sensor for outputting a unit crank angle signal POS with every unit angle, and detects a reference cam angle position and a reference crank angle position by detecting a different part in an output period of the unit cam angle signal CAM and the unit crank angle signal POS. The rotational phase of the camshaft is detected from a deviation between an enumerated value vCAMCNT3 of the unit cam angle signal CAM with the reference cam angle position as a reference and an enumerated value vCRACNT72 of the unit crank angle signal POS with the reference crank angle position as a reference. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cam phase detection device for an internal combustion engine that detects a rotation phase of a camshaft with respect to a crankshaft.

In Patent Document 1, in a 6-cylinder engine equipped with a variable valve timing mechanism that can vary the rotational phase of the camshaft with respect to the crankshaft, three teeth are formed at equal intervals on the outer periphery of the rotor attached to the camshaft. A cylinder discriminating sensor for detecting a tooth by an electromagnetic pickup and generating a cylinder discriminating signal is provided. On the other hand, a tooth is formed on the outer periphery of a rotor mounted on a crankshaft every 10 degrees, and the tooth is detected by an electromagnetic pickup to generate a unit angle signal. A rotational speed sensor that detects the rotational phase of the camshaft relative to the crankshaft from the rotational phase difference from the time of generation of the cylinder discrimination signal to the unit angle signal corresponding to the reference piston position, and from the unit angle signal It is disclosed that cylinder discrimination is performed based on the presence or absence of a cylinder discrimination signal in a set detection section.
JP 2005-291141 A

  By the way, as described above, when the rotational phase difference is detected from the time difference from when the cylinder discrimination signal indicating the reference rotational position of the camshaft is generated until the crankshaft reaches the reference rotational position, the rotational phase difference is detected by the cylinder discrimination signal. Therefore, there is a problem in that the variable valve timing mechanism cannot be feedback-controlled with high speed and high accuracy because the detection period of the rotational phase difference becomes long particularly in the low rotation range.

  The present invention has been made in view of the above problems, and provides a cam phase detection device capable of detecting a rotation phase of a camshaft relative to a crankshaft with a sufficiently short period even at a low rotation. For the purpose.

  Therefore, the invention described in claim 1 outputs a unit cam angle signal every time the camshaft rotates by a unit angle, and the output cycle of the unit cam angle signal is at least one place per one rotation of the camshaft. A cam angle sensor that is set to an angle different from the unit angle, and each unit cam angle signal is detected by detecting a location where an output cycle of the unit cam angle signal is set to an angle different from the unit angle. A corresponding cam angle position is detected, and a rotational phase of the camshaft with respect to the crankshaft is detected from a correlation between the detected cam angle position and the crank angle position.

According to the above invention, it is possible to detect the angular position of the camshaft where the output cycle of the unit cam angle signal is different by detecting the location where the output cycle of the unit cam angle signal is different, and the unit cam angle signal from the reference position The number of occurrences indicates the rotation angle of the camshaft from the reference position.
Therefore, it becomes possible to detect the cam angle position with a short angular period, and thereby the rotational phase update period is made shorter than the cylinder discrimination period, so that the variable valve timing mechanism can be operated at high speed and high speed even at low revolutions. Feedback control can be performed with high accuracy.

  According to a second aspect of the present invention, a unit crank angle signal is output every time the crankshaft rotates by a unit angle, and an output cycle of the unit crank angle signal is at least one unit per one rotation of the crankshaft. A crank angle sensor that is set to an angle different from the angle is provided, and each unit crank angle signal can be handled by detecting a location where the output cycle of the unit crank angle signal is set to an angle different from the unit angle. The crank angle position to be detected is detected.

According to the above invention, by detecting a portion where the output cycle of the unit crank angle signal is different, the angular position of the crankshaft having a different output cycle of the unit crank angle signal can be detected, and the unit crank angle signal from the reference position is detected. The number of occurrences indicates the rotation angle of the crankshaft from the reference position.
Therefore, as with the cam angle position, the crank angle position can be detected with a short angle cycle, and the camshaft angle position and the crankshaft angle position can be detected with a single sensor for each short angle cycle. The rotation phase can be detected at a cycle shorter than the cylinder discrimination cycle.

  The invention according to claim 3 outputs a unit cam angle signal every time the camshaft rotates by a unit angle, and the output cycle of the unit cam angle signal is at least one unit per one rotation of the camshaft. Reference cam angle position detection for detecting a reference cam angle position based on a cam angle sensor set to an angle different from the angle and a location where the output cycle of the unit cam angle signal is set to an angle different from the unit angle Means, a first counting means for counting the unit cam angle signal on the basis of the reference cam angle position, a unit crank angle signal being output each time the crankshaft rotates by a unit angle, and the unit crank angle signal A crank angle sensor in which the output cycle is set to an angle different from the unit angle at at least one location per rotation of the crankshaft, and the unit Reference crank angle position detecting means for detecting a reference crank angle position based on a position where an output cycle of the rank angle signal is set to an angle different from the unit angle; and the unit crank angle signal based on the reference crank angle position. Rotation phase detection for detecting the rotation phase of the camshaft with respect to the crankshaft by comparing the count value by the second count means, the count value by the first count means, and the count value by the second count means Means.

  According to the above invention, the location where the output period of the unit cam angle signal and the unit crank angle signal is set to an angle different from the unit angle is specified in advance, and the counting result by each counting means is the rotation angle from the reference angle position, respectively. Therefore, comparing the two count values compares the angular position of the camshaft with the angular position of the crankshaft, whereby the rotational phase of the camshaft relative to the crankshaft can be detected.

Therefore, the angular position of the camshaft and the angular position of the crankshaft can be detected with a short angular period, thereby detecting the rotational phase with a short period even at low revolutions, and the variable valve timing mechanism can be detected at high speed and high accuracy. It becomes possible to perform feedback control.
According to a fourth aspect of the present invention, the rotational phase detecting means is configured such that a deviation between a count value obtained by the first counting means and a count value obtained by the second counting means, and the unit crank angle signal and the unit cam angle. The rotational phase is detected based on a phase difference with a signal.

According to the above invention, the deviation between the count value by the first count means and the count value by the second count means indicates the phase difference of each reference angle position, with the unit angle as the minimum unit. By adding the phase difference between the unit crank angle signal and the unit cam angle signal, the rotational phase can be detected with a resolution finer than the unit angle.
Therefore, the rotational phase can be detected with a short angular period and with high accuracy.

Embodiments of the present invention will be described below.
FIG. 1 is a configuration diagram of a four-cylinder gasoline internal combustion engine in the embodiment.
In FIG. 1, an electronic control throttle 104 that opens and closes a throttle valve 103 b by a throttle motor 103 a is interposed in an intake pipe 102 of an internal combustion engine 101.
Then, air is sucked into the combustion chamber 106 through the electronic control throttle 104 and the intake valve 105.

An electromagnetic fuel injection valve 131 is provided at the intake port 130 of each cylinder.
When the fuel injection valve 131 is driven to open by an injection pulse signal from an engine control unit (hereinafter referred to as ECU) 114, the fuel injection valve 131 injects fuel adjusted to a predetermined pressure toward the intake valve 105.
The fuel sucked into the combustion chamber 106 is ignited and burned by spark ignition by a spark plug (not shown).

The combustion exhaust in the combustion chamber 106 is discharged to the exhaust pipe through the exhaust valve 107, purified by the front catalyst 108 and the rear catalyst 109, and then released into the atmosphere.
The intake valve 105 and the exhaust valve 107 are driven to open and close by cams provided on the intake side camshaft 134 and the exhaust side camshaft 110, respectively. The intake side camshaft 134 is provided with a variable valve timing mechanism 113. ing.

The variable valve timing mechanism 113 is a mechanism that changes the valve timing of the intake valve 105 by changing the rotational phase of the intake camshaft 134 with respect to the crankshaft 120.
FIG. 2 shows the structure of the variable valve timing mechanism 113.
The variable valve timing mechanism 113 is fixed to a sprocket 25 that rotates in synchronization with the crankshaft 120, and a first rotating body 21 that rotates integrally with the sprocket 25, and one end of the intake camshaft 134 by a bolt 22a. And a cylindrical shape that meshes with the inner circumferential surface of the first rotating body 21 and the outer circumferential surface of the second rotating body 22 by the helical spline 26. Intermediate gear 23.

A drum 27 is connected to the intermediate gear 23 via a triple screw 28, and a torsion spring 29 is interposed between the drum 27 and the intermediate gear 23.
The intermediate gear 23 is biased in the retarding direction (left direction in FIG. 2) by a torsion spring 29. When a voltage is applied to the electromagnetic retarder 24 to generate a magnetic force, the intermediate gear 23 passes through the drum 27 and the triple thread screw 28. Is moved in the advance direction (right direction in FIG. 2).

Depending on the position of the intermediate gear 23 in the axial direction, the relative phase of the rotators 21 and 22 changes, and the phase of the intake camshaft 134 with respect to the crankshaft 120 changes.
The electromagnetic retarder 24 is driven and controlled according to the operating state of the engine by a control signal from the ECU 114.
The variable valve timing mechanism 113 is not limited to the structure shown in FIG. 2, and a known variable valve timing mechanism that changes the rotational phase of the camshaft relative to the crankshaft can be applied.

The ECU 114 includes a microcomputer, and controls the electronic control throttle 104, the variable valve timing mechanism 113, the fuel injection valve 131, and the like by arithmetic processing based on detection signals from various sensors.
The various sensors include an accelerator opening sensor 116 for detecting the accelerator opening, an air flow meter 115 for detecting the intake air amount Q of the engine 101, a crank angle sensor 117 for detecting the crank angle, and an opening TVO of the throttle valve 103b. A throttle sensor 118 for detecting, a water temperature sensor 119 for detecting the coolant temperature of the engine 101, and a cam angle sensor 132 for detecting the cam angle are provided.

  The crank angle sensor 117 detects the detected portion of the signal plate that is pivotally supported by the crankshaft 120, thereby generating a unit crank angle signal POS that falls at every unit crank angle of 10 deg as shown in FIG. Although the output is performed, the falling cycle is set at one position per one rotation of the crankshaft 120 so that the crank angle is 30 deg different from the unit angle.

  That is, the crank angle sensor 117 is a sensor that detects the rotation of the crankshaft 120 in units of a crank angle of 10 deg. A portion where the output cycle of the unit crank angle signal POS is set to a crank angle of 30 deg is a constant crank angle position. The rotation angle of the crankshaft 120 is detected as an angle from the angular position where the output cycle is set to the crank angle 30 deg by determining the portion where the output cycle is set to the crank angle 30 deg. can do.

The 30 deg period portion of the unit crank angle signal POS is set by, for example, missing two detected portions continuously.
The ignition of the 4-cylinder engine 101 in this embodiment is performed in the order of # 1 cylinder → # 3 cylinder → # 4 cylinder → # 2 cylinder, and the stroke phase difference between the cylinders is 180 deg in crank angle, 180 deg. Ignition occurs at intervals.

  The intake-side camshaft 134 rotates half a revolution of the crankshaft 120, and the cam angle sensor 132 detects a detected portion of the signal plate that is pivotally supported by the intake-side camshaft 134. As shown in FIG. 3, a unit cam angle signal CAM having a rising / falling edge is output at every unit crank angle 10 deg (cam angle 5 deg), but rises at one place per one rotation of the intake camshaft 134. The edge period from the start to the fall is set to be a crank angle of 30 deg (cam angle of 15 deg) different from the unit angle.

  That is, the cam angle sensor 132 is a sensor that detects the rotation of the camshaft 134 in units of 5 deg cam angle, and the portion where the output cycle of the unit cam angle signal CAM is set to 30 deg is a constant cam angle position. Therefore, the rotation angle of the camshaft 134 is detected as an angle from the angular position where the output cycle is set to the crank angle 30 deg. By determining the portion where the output cycle is set to the crank angle 30 deg. can do.

Here, between the portion where the cycle from the rising to the falling of the unit cam angle signal CAM is the crank angle 30 deg (reference cam angle position), the portion where the falling cycle of the unit crank angle signal POS is 30 deg (reference crank) Corner position) appears twice.
The portion where the cycle from the rise to the fall of the unit cam angle signal CAM is the crank angle of 30 deg is set, for example, by providing a detected portion whose circumferential width is three times that of the other.

The unit angle can be set as appropriate according to the resolution required for detecting the rotational phase, but is preferably set to a minute crank angle of about 5 deg to 20 deg.
The ECU 114 detects the rotation phase of the intake camshaft 134 with respect to the crankshaft 120 based on the detection signals of the crank angle sensor 117 and the cam angle sensor 132, and determines the detection result of the rotation phase and the target rotation phase. Based on the deviation, the variable valve timing mechanism 113 (electromagnetic retarder 24) is feedback-controlled.

Hereinafter, how the ECU 114 detects the rotational phase will be described in detail.
The flowchart in FIG. 4 is executed every time the unit crank angle signal POS falls (every crank angle 10 deg). In step S41, the counter vCRACNT72 for counting the falling of the unit crank angle signal POS is incremented by one. To do.
In the next step S42, the falling period TPOS of the unit crank angle signal POS is measured based on the time difference from the previous execution of this routine to this time.

In step S43, a period ratio ΔTPOS (period ratio ΔTPOS = current value / previous value), which is a ratio between the current value and the previous value of the period TPOS, is calculated.
In step S44, it is determined whether or not the period TPOS measured this time is a result of measuring a 30 deg period part by determining whether or not the period ratio ΔTPOS is greater than or equal to a threshold SL1 stored in advance. To do.

If the period ratio ΔTPOS is equal to or greater than the threshold value SL1, it is determined that the current unit crank angle signal POS corresponds to the reference crank angle position (reference crank angle position detecting means), and the process proceeds to step S45.
In step S45, it is determined whether or not the flag FCRA is 1. If the flag FCRA = 0, the flag FCRA is set to 1 in step S46 and then the process proceeds to step S47 to reset the counter vCRACNT72 to 0. To do.

On the other hand, if the flag FCRA is 1, the process proceeds to step S48, the flag FCRA is reset to 0, the process bypasses step S47, and this routine is terminated as it is.
That is, if the counter vCRACNT72 is reset to 0 because the current 30 deg period portion is detected, it will not be reset to 0 when the next 30 deg period portion is detected, and the second 30 deg period portion will be detected. At this timing, it is reset again to 0, and as shown in FIG. 3, it is reset to 0 only once every two times of the 30 deg period, in other words, every time the crankshaft 120 rotates twice ( Second counting means).

The flowchart of FIG. 5 is executed for each rising / rising edge of the unit cam angle signal CAM (every crank angle 10 deg). In step S51, the counter camcnt for counting the rising / rising edge of the unit cam angle signal CAM is set to 1. Just count up.
In the next step S52, it is determined whether or not the counter camcnt has been counted up to 3.

When the counter camcnt is counted up to 3, the process proceeds to step S53, where the counter camcnt is reset to 0. In the next step S54, the counter vCAMCNT3 is incremented by 1.
That is, the counter vCAMCNT3 is a counter that is counted up every three rising and rising edges of the unit cam angle signal CAM.

In step S55, the period TCAM of the rising / rising edge of the unit cam angle signal CAM is measured based on the time difference from the previous execution of this routine to the current time.
In step S56, a cycle ratio ΔTCAM (cycle ratio ΔTCAM = current value / previous value), which is a ratio between the current value of the cycle TCAM and the previous value, is calculated.
In step S57, it is determined whether or not the cycle ratio ΔTCAM is greater than or equal to a previously stored threshold value SL2, so that the cycle TCAM measured this time is a result of measuring a cycle portion of 30 deg in crank angle. Judging.

Note that the period TPOS and the period TCAM both correspond to a crank angle of 10 deg, and the portions having different periods are set to a crank angle of 30 deg. Therefore, the threshold value SL1 and the threshold value SL2 can be set to the same value. .
If the cycle ratio ΔTCAM is equal to or greater than the threshold value SL2, it is determined that the current unit cam angle signal CAM corresponds to the reference cam angle position (reference cam angle position detecting means), and the process proceeds to step S58.

In step S58, the counter vCAMCNT3 is reset to zero.
Therefore, as shown in FIG. 3, the counter vCAMCNT3 is reset to 0 at the reference cam angle position (30 deg period portion) detected every rotation of the intake side camshaft 134 (first counting means). .
In step S59, the difference vVTCCLK between the current time and the time when the unit crank angle signal POS is detected separately, that is, the rising and rising edges of the unit cam angle signal CAM is detected from the falling of the unit crank angle signal POS. The time difference until it is calculated (the phase difference between the unit crank angle signal POS and the unit cam angle signal CAM) is calculated.

The flowchart of FIG. 6 is executed every time the unit crank angle signal POS falls (every crank angle 10 deg), and in step S61, the detection time of the falling of the unit crank angle signal POS used for the calculation in step S59 is stored. To do.
In step S62, it is determined whether or not the counter vCRACNT72 passes through a 30-deg period portion in which the counter vCRACNT72 is not reset to 0 by determining whether or not the value of the counter vCRACNT72 is 34 or more.

When the value of the counter vCRACNT72 is 34 or more, 2 is added to the counter vCRACNT72 in order to compensate for the two unit crank angle signals POS that are missing in the 30 deg period.
Thus, the value of the counter vCRACNT72 can correctly indicate the rotation angle from the reference crank angle position (30 deg period portion).

In step S64, a difference vVTCCNT (vVTCCNT = vCRACNT72−vCAMCNT3 × 3) between the counter vCRACNT72 and the number obtained by multiplying the counter vCAMCNT3 by 3 is calculated. This is because the counter vCRACNT 72 is counted up every 10 degrees in terms of the crank angle, so that the same count value is made every 10 degrees.

The deviation vVTCCNT indicates the crank angle from the reference crank angle position to the reference cam angle position in units of a crank angle of 10 deg.
In step S65, it is determined whether or not the deviation vVTCCNT is calculated as a negative value.
When the deviation vVTCCNT is a negative value, the process proceeds to step S66, and 72 is added to the deviation vVTCCNT so that the deviation vVTCCNT represents the crank angle from the reference crank angle position to the reference cam angle position. To do.

  The flowchart of FIG. 7 is executed for every rising edge and rising edge of the unit cam angle signal CAM (every crank angle 10 deg). In step S71, it is determined whether or not this time is the count-up timing of the counter vCAMCNT3, and the count-up is performed. Only when it is timing, the steps after step S72 are executed. That is, the process after step S72 is performed for every 30 degrees of crank angles.

In step S72, the phase difference vVTCCLK is divided by the period TPOS of the unit crank angle signal POS by dividing the phase difference vVTCCLK between the falling edge of the unit crank angle signal POS and the rising / rising edge of the unit cam angle signal CAM. The number corresponding to 10 deg cycle is obtained (vVTCTIM = vVTCCLK / TPOS).
In step S73, the crank angle vVTCANG from the reference crank angle position to the reference cam angle position is calculated as vVTCANG = (vVTCTIM + vVTCCNT) × 10 based on the vVTCTIM and vVTCCNT.

Further, in the next step S74, the actually calculated angle vVTCANG is subtracted from 540 deg which is the data of the angle vVTCANG when the rotation phase of the intake camshaft 134 is controlled to the most retarded angle by the variable valve timing mechanism 113. Thus, the advance amount vREVTC of the rotational phase is calculated as described above, and the advance amount vREVTC of the rotational phase is detected every 30 degrees of the crank angle, and this advance amount vREVTC is calculated from the engine operating conditions. The variable valve timing mechanism 113 is feedback-controlled so as to approach the set target advance amount.

Therefore, even when the engine is running at a low speed, the rotational phase can be detected in a sufficiently short time period, and the variable valve timing mechanism 113 can be feedback-controlled with high speed and high accuracy.
The reason why the rotation phase detection cycle is set to every 30 deg crank angle is that the value of the counter vCRACNT72 is not counted up every 10 deg in the 30 deg cycle portion. This is because a significantly different advance amount is calculated.

In the above embodiment, the unit angle is set to 10 deg crank angle, and the rotation phase is detected every 30 deg crank angle. However, it is obvious that the present invention is not limited to these angle settings, and the cam angle sensor 132 is not limited thereto. However, it is possible to generate a unit cam angle signal CAM that falls or rises for each unit angle.
By the way, based on detection signals of the crank angle sensor 117 and the cam angle sensor 132, a cylinder located in a predetermined piston is determined for each stroke phase difference between the cylinders, and the cylinder determination result is used as fuel injection control for each cylinder, It can be used for ignition timing control.

Hereinafter, the state of cylinder discrimination by the ECU 114 will be described in detail.
8 is executed every time the unit crank angle signal POS falls. In step S81, the counter vCRACNTCYL is incremented by 1 (see FIG. 12), and in the next step S12, the counter vCNTFST is incremented by 1. Up (see FIG. 13).
The flowchart of FIG. 9 is executed every time the unit crank angle signal POS falls. In step S91, the time interval from the previous execution to the current execution is set as the falling period TPOS (time period) of the unit crank angle signal POS. ) This time.

In step S92, a ratio ΔTPOS between the current value of the period TPOS and the previous value (period ratio ΔTPOS = current value / previous value) is calculated.
In step S93, it is determined whether or not the period ratio ΔTPOS exceeds a threshold SL1 stored in advance.
The threshold SL1 is set to a value that exceeds the period ratio ΔTPOS when the current value is a detection result of a falling period of 30 degrees.

Here, if the cycle ratio ΔTPOS exceeds the threshold value SL1, it is determined that it is the reference crank angle position, and the process proceeds to step S94 to reset the counter vCRACNTCYL to zero.
That is, as shown in FIG. 12, the counter vCRACNTCYL is counted up every time the unit crank angle signal POS falls, and when the unit crank angle signal POS falls in a cycle of 30 deg (every crankshaft 120 rotation). To 0).

If the period ratio ΔTPOS does not exceed the threshold value SL1, it is determined that the current value is not the result of detecting a 30 deg falling period, and the process proceeds to step S95, bypassing step S94.
In step S95, the current value of the cycle TPOS of the unit crank angle signal POS is set to the previous value.

The flowchart of FIG. 10 is executed for each rising / rising edge of the unit cam angle signal CAM. In step S101, the time interval from the previous execution to the current execution is set as the rising / falling cycle TCAM of the unit cam angle signal CAM. Set to the current value.
In step S102, a ratio ΔTCAM (period ratio ΔTCAM = current value / previous value) between the current value and the previous value of the cycle TCAM is calculated.

In step S103, it is determined whether or not the cycle ratio ΔTCAM exceeds a threshold SL2 stored in advance.
The threshold value SL2 is set to a value that exceeds the cycle ratio ΔTCAM when the current value is a detection result of a rising / falling cycle of 30 degrees.
Here, if the cycle ratio ΔTCAM exceeds the threshold value SL2, it is determined that the position is the reference cam angle position, the process proceeds to step S104, and the counter vCNTFST is reset to 0.

That is, as shown in FIG. 13, the counter vCNTFST is counted up every time the unit crank angle signal POS falls, and when the unit cam angle signal CAM falls at a cycle of 30 degrees (every rotation of the camshaft 134). , Every two revolutions of the crankshaft 120).
If the period ratio ΔTCAM does not exceed the threshold value SL2, it is determined that the current value is not the result of detecting a rising / falling period of 30 deg, and the process proceeds to step S105, bypassing step S104.

In step S105, the current value of the cycle TCAM of the unit cam angle signal CAM is set to the previous value.
The flowchart of FIG. 11 is executed every time the unit crank angle signal POS falls, and in step S111, it is determined whether or not the value of the counter vCRACNTCYL is zero.
When the value of the counter vCRACNTCYL is 0, it is determined that it is the cylinder discrimination timing, and the process proceeds to step S112.

In step S112, it is determined whether or not the counter vCNTFST is 40 or more.
If the counter vCNTFST is 40 or more, the process proceeds to step S113, where "3" is set to the cylinder discrimination value vCYLCNT.
On the other hand, if the counter vCNTFST is less than 40, the process proceeds to step S114, and "1" is set to the cylinder discrimination value vCYLCNT.

The initial value of the cylinder discrimination value vCYLCNT is “0”. “0” is held until “3” or “1” is set to the cylinder discrimination value vCYLCNT in step S113 or step S114, and vCYLCNT = “ “0” indicates a cylinder unknown state.
If it is determined in step S101 that the value of the counter vCRACNTCYL is not 0, the process proceeds to step S105, and it is determined whether or not the value of the counter vCRACNTCYL is 17.

The counter vCRACNTCYL = 17 is an intermediate point between the time when the value of the counter vCRACNTCYL becomes 0 and then becomes 0, and it is determined that it is the cylinder discrimination timing even when the counter vCRACNTCYL = 17. Then, the process proceeds to step S116.
Since the counter vCRACNTCYL is reset to 0 every time the crankshaft 120 makes one rotation, the timing of the counter vCRACNTCYL = 0 and the counter vCRACNTCYL = 17 is the timing of every crank angle 180 deg. This corresponds to the stroke phase difference between the cylinders at 101, and cylinder discrimination for each crank angle of 180 deg, for example, sequentially determines the cylinders of the intake TDC.

In step S116, the cylinder discrimination value vCYLCNT is set to the previous value +1.
Therefore, when the cylinder discrimination value vCYLCNT is set to “1” by determining that the counter vCNTFST is less than 40 when the value of the counter vCRACNTCYL is 0, the next time the counter vCRACNTCYL = 17 When the counter vCRACNTCYL is 0, the counter vCNTFST is determined to be 40 or more and then set to “3”. Next, the counter vCRACNTCYL is set to “3”. = 17, the count is incremented by 1 to "4", and the above processing is repeated until the count returns to 1 and counts up to 4 again (FIG. 14). reference).

The cylinder discrimination value vCYLCNT indicates what number of cylinders # 1 →→ # 3 → # 4 →→ # 2 in the ignition order next becomes the intake TDC, for example, vCYLCNT = 3. Sometimes, the next intake TDC is the # 4 cylinder.
Since the value of the counter vCRACNTCYL is reset to 0 twice while the counter vCNTFST is reset to 0, even when the counter vCRACNTCYL = 0, the timing is immediately after the counter vCNTFST is reset to 0. Depending on whether or not, the value of the counter vCNTFST differs by a value corresponding to one rotation of the crankshaft 120.

Therefore, by determining whether or not the counter vCNTFST is less than 40, the timing when the counter vCRACNTCYL = 0 can be clearly distinguished as the intake TDC timing of different cylinders, and cylinder discrimination can be performed with high accuracy. become.
Even in the case where the variable valve timing mechanism 113 is provided as in the present embodiment, the variable shaft timing mechanism 113 can identify a value having a difference for one rotation in step S112. Even if the rotation phase of the intake camshaft 134 with respect to 120 changes and the value of the counter vCNTFST when the counter vCRACNTCYL = 0 is changed, the change width is sufficiently large for the difference of one rotation. Since it is small, cylinder discrimination is not affected.

Here, technical ideas other than the claims that can be grasped from the above embodiment will be described together with the effects thereof.
(A) detecting a location where the output cycle is set to an angle different from the unit angle based on a ratio between the current value and the previous value of the cycle of the unit cam angle signal and / or the unit crank angle signal. The cam phase detection device for an internal combustion engine according to any one of claims 1 to 4.

According to the above invention, since the current value of the time period and the previous value become different due to the different angle period, the ratio of the current value of the time period and the previous value indicates that the output period of the signal is the unit angle. Detect locations set at different angles.
Here, by calculating the ratio between the current value and the previous value, the influence of the engine rotational speed at that time can be eliminated, and a location set to an angle different from the unit angle can be easily detected.
(B) The cam phase detection device for an internal combustion engine according to any one of claims 1 to 4, wherein the unit angle is smaller than a crank angle corresponding to a stroke phase difference between cylinders.

According to the above invention, since the output cycle of the unit cam angle signal and the unit crank angle signal is smaller than the crank angle corresponding to the stroke phase difference between the cylinders, the camshaft relative to the crankshaft with an angular cycle shorter than the stroke phase difference. It becomes possible to detect the rotational phase difference.
The unit angle is preferably an angle that equally divides the crank angle corresponding to the stroke phase difference between the cylinders (crank angle 180 deg for four cylinders) into a plurality of parts, and is further set to about 5 deg to 20 deg. It is more preferable.
(C) third counting means for counting the unit crank angle signal with reference to the reference cam angle position;
Cylinder discrimination timing detection means for detecting cylinder discrimination timing based on the count value by the second counting means;
Cylinder discrimination means for discriminating a cylinder at a predetermined piston position based on a count value by the third counting means at the cylinder discrimination timing;
The cam phase detection device for an internal combustion engine according to claim 3 or 4, characterized by comprising:

According to the above-described invention, cylinder discrimination can be performed using the signals of the crank angle sensor and the cam angle sensor that can detect the rotational phase with a short angular period.
(D) the third counting means resets the count value of the unit crank angle signal to 0 every time the camshaft makes one rotation;
The cam phase detection apparatus for an internal combustion engine according to claim (c), wherein the cylinder discrimination timing detection means detects a cylinder discrimination timing for each stroke phase difference between the cylinders.

  According to the above invention, cylinder discrimination is performed by determining the rotation angle of the camshaft at that time based on the difference in the count value of the third counting means for each stroke phase difference between the cylinders.

1 is a system configuration diagram of an internal combustion engine in an embodiment. Sectional drawing which shows the variable valve timing mechanism in embodiment. The timing chart which shows the characteristic of the various signals used for the detection of a rotation phase. The flowchart which shows the counting process of the unit crank angle signal POS in rotation phase detection. The flowchart which shows the counting process of the unit cam angle signal CAM in rotation phase detection. The flowchart which shows the detection of the rotation phase by the unit angle in rotation phase detection. The flowchart which shows the detection of the final rotation phase in a rotation phase detection. The flowchart which shows the signal count process in a cylinder discrimination | determination process. The flowchart which shows the detection process of the reference | standard crank angle position in a cylinder discrimination | determination process. The flowchart which shows the detection process of the reference | standard cam angle position in a cylinder discrimination | determination process. The flowchart which shows the cylinder discrimination | determination process based on a count value. 6 is a timing chart showing characteristics of a unit cam angle signal CAM, a unit crank angle signal POS, and a counter vCRACNTCYL used for cylinder discrimination processing. 6 is a timing chart showing characteristics of a unit cam angle signal CAM, a unit crank angle signal POS, and a counter vCNTFST used for cylinder discrimination processing. 6 is a timing chart showing characteristics of a counter vCRACNTCYL, a counter vCNTFST, and a cylinder discrimination value vCYLCNT used for cylinder discrimination processing.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Internal combustion engine, 105 ... Intake valve, 113 ... Variable valve timing mechanism, 114 ... Engine control unit, 117 ... Crank angle sensor, 120 ... Crank shaft, 132 ... Cam angle sensor, 134 ... Cam shaft

Claims (4)

A cam phase detection device for an internal combustion engine comprising a variable valve timing mechanism for varying a rotational phase of a camshaft relative to a crankshaft,
Each time the camshaft rotates by a unit angle, a unit cam angle signal is output, and the output cycle of the unit cam angle signal is set to an angle different from the unit angle at at least one location per rotation of the camshaft. Cam angle sensor
By detecting the location where the output cycle of the unit cam angle signal is set to an angle different from the unit angle, each unit cam angle signal detects the corresponding cam angle position, and the detected cam angle position A cam phase detection device for an internal combustion engine, wherein the rotational phase is detected from a correlation between the engine and a crank angle position. Each time the crankshaft rotates by a unit angle, a unit crank angle signal is output, and the output cycle of the unit crank angle signal is set to an angle different from the unit angle at at least one location per rotation of the crankshaft. Equipped with a crank angle sensor
2. The crank angle position corresponding to each unit crank angle signal is detected by detecting a place where an output cycle of the unit crank angle signal is set to an angle different from the unit angle. A cam phase detection device for an internal combustion engine as described. A cam phase detection device for an internal combustion engine comprising a variable valve timing mechanism that varies a rotational phase of a camshaft relative to a crankshaft,
Each time the camshaft rotates by a unit angle, a unit cam angle signal is output, and the output cycle of the unit cam angle signal is set to an angle different from the unit angle at at least one location per rotation of the camshaft. A cam angle sensor,
Reference cam angle position detecting means for detecting a reference cam angle position based on a location where an output cycle of the unit cam angle signal is set to an angle different from the unit angle;
First counting means for counting the unit cam angle signal with reference to the reference cam angle position;
Each time the crankshaft rotates by a unit angle, a unit crank angle signal is output, and the output cycle of the unit crank angle signal is set to an angle different from the unit angle at at least one location per rotation of the crankshaft. A crank angle sensor,
Reference crank angle position detecting means for detecting a reference crank angle position based on a location where an output cycle of the unit crank angle signal is set to an angle different from the unit angle;
Second counting means for counting the unit crank angle signal with reference to the reference crank angle position;
A rotational phase detection means for detecting the rotational phase by comparing a count value obtained by the first count means with a count value obtained by the second count means;
A cam phase detection device for an internal combustion engine, comprising:   The rotational phase detection means is based on a deviation between a count value by the first count means and a count value by the second count means, and a phase difference between the unit crank angle signal and the unit cam angle signal. The cam phase detection device for an internal combustion engine according to claim 3, wherein the rotation phase is detected.

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