JP4805962B2 - Cam phase detector for internal combustion engine - Google Patents

Description

  The present invention relates to a cam phase detection device that detects the rotational phase that is variable by the variable valve timing mechanism in an internal combustion engine that includes a variable valve timing mechanism that varies the rotational phase of the camshaft relative to the 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 rotation phase is detected from the difference between the generation of the cylinder discrimination signal indicating the reference rotation position of the camshaft and the crankshaft reaching the reference rotation position, the rotation phase is generated by the cylinder discrimination signal. Since the rotation phase is detected every time, the rotation phase detection cycle becomes long particularly in a low rotation range, and there is a problem that the variable valve timing mechanism cannot be feedback-controlled with high speed and high accuracy.

  The present invention has been made in view of the above problems, and is capable of detecting the rotational phase of the camshaft relative to the crankshaft with a sufficiently short period even at a low rotational speed. The purpose is to provide.

Therefore, the invention described in claim 1 is a cam phase detection device for an internal combustion engine provided with a variable valve timing mechanism for making the rotation phase of the camshaft relative to the crankshaft variable, each time the camshaft rotates by a unit angle. A first cam sensor that outputs a first cam angle signal, and a second cam angle signal that outputs a second cam angle signal for discriminating a cylinder at a specific piston position at each reference cam angle position for each phase difference between strokes. A cam sensor; cylinder determining means for determining a cylinder at a specific piston position based on the second cam angle signal; reference crank angle position detecting means for detecting a reference crank angle position of the crankshaft; and the second cam. Based on the number of occurrences of the first cam angle signal from the reference cam angle position identified by the angle signal and the discrimination result of the cylinder, the first cam angle signal is Another is configured to include a cam phase detecting means for detecting the rotational phase based on a phase difference between the reference crank angle position of the first cam angle signal which is the identified.

According to the above invention, the first cam angle signal can be identified based on the number of occurrences of the first cam angle signal from the reference cam angle position identified by the second cam angle signal and the discrimination result of the cylinder . It becomes possible to detect the rotational phase for each occurrence.
Accordingly, the rotational phase can be detected with a sufficiently short cycle even at the time of low rotation, and the variable valve timing mechanism can be feedback-controlled with high speed and high accuracy even in the low rotation range.

According to a second aspect of the present invention, the value of the first counter is incremented every time the first cam angle signal is output, and the value of the first counter is incremented every time the cylinder discrimination result is updated by the cylinder discrimination means. First counter means for resetting is further provided, and the cam phase detecting means discriminates the first cam angle signal outputted most recently from the discrimination result of the cylinder and the value of the first counter.

According to a third aspect of the present invention, the second cam sensor outputs a second cam angle signal having a different number for each phase difference between strokes between the cylinders, and further, the first cam angle signal is Second count means that counts up the value of the second counter each time it is output, and resets the value of the second counter every time the second cam angle signal is output, and the second cam angle signal is output And a third counting means for counting up the value of the third counter each time the second counter is counted and resetting the value of the third counter when the value of the second counter reaches the first set value. The means updates the cylinder discrimination result based on the value of the third counter when the value of the second counter reaches the second set value.

According to a fourth aspect of the present invention, there is provided a cam phase detecting device for an internal combustion engine having a variable valve timing mechanism for varying a rotational phase of the camshaft relative to the crankshaft, wherein one reference crank is provided per one revolution of the crankshaft. Reference crank angle position detecting means for detecting an angular position, a first cam sensor for outputting a first cam angle signal each time the cam shaft rotates by a unit angle, and high / low for each half rotation of the cam shaft. A second cam sensor that outputs a second cam angle signal to be switched; and a first cam angle signal generated from a reference cam angle position identified by a high / low switching of the second cam angle signal. A cam angle signal is identified, and the rotational phase is detected based on a phase difference between the identified first cam angle signal and the reference crank angle position. Configured to include arm and the phase detecting means.

According to the above invention, the reference cam angle position can be detected based on the high / low switching of the second cam angle signal, and the first cam angle is determined based on the number of occurrences of the first cam angle signal from the reference cam angle position. By identifying the signal, the rotational phase can be detected every time the first cam angle signal is generated.

According to a fifth aspect of the present invention, the cam phase detecting means counts the first cam angle signal output thereafter with reference to the rising or falling edge of the second cam angle signal, so that the first cam angle signal is output. The cam angle signal is identified.

According to a sixth aspect of the present invention, the cam phase detecting means detects a crank angle from the reference crank angle position to the latest first cam angle signal, while the number of occurrences of the first cam angle signal and the first A crank angle from the reference cam angle position to the latest first cam angle signal is calculated from the angle pitch of the cam angle signal, and the reference angle is calculated from the crank angle from the reference crank angle position to the latest first cam angle signal. By subtracting the crank angle from the cam angle position to the latest first cam angle signal, the phase difference between the reference crank angle position and the reference cam angle position is calculated every time the first cam angle signal is generated. I made it.

According to the above invention, the crank angle from the reference cam angle position to the latest first cam angle signal is subtracted from the crank angle from the reference crank angle position to the latest first cam angle signal. The crank angle up to the reference cam angle position is obtained, and this crank angle changes when the rotational phase of the camshaft relative to the crankshaft is made variable, so that the rotational phase is detected.
Therefore, the rotation phase as the crank angle from the reference crank angle position to the reference cam angle position can be obtained for each first cam angle signal.

In the invention according to claim 7, the reference crank angle position detection means outputs a unit crank angle signal every time the crankshaft rotates by a unit angle, and the unit crank angle signal makes one rotation of the crankshaft. A crank angle sensor missing at least one hit is provided, a spot where the unit crank angle signal is missing is detected, and the reference crank angle position is detected based on the detected missing spot.

According to the above invention, since the unit crank angle signal from the crank angle sensor is lost at every fixed crank angle position, for example, the missing portion is detected from the generation cycle of the unit crank angle signal, and the missing portion is used as a reference. The reference crank angle position is detected.
Therefore, it is not necessary to provide a sensor for detecting the reference crank angle position in addition to the sensor for detecting the unit crank angle, and the system configuration can be simplified.

In the invention according to claim 8, the cam phase detection means detects a crank angle from the reference crank angle position to the latest first cam angle signal based on the number of occurrences of the unit crank angle signal, and The number of occurrences is corrected based on whether or not the missing portion is included between the reference crank angle position and the latest first cam angle signal.

According to the above invention, the crank angle from the reference crank angle position to the latest first cam angle signal can be detected based on the number of unit crank angle signals generated, and the detected crank angle and the latest first cam angle are detected. The rotational phase can be detected from the signal identification result, but if the missing portion of the crank angle signal is included between the reference crank angle position and the latest first cam angle signal, the number of occurrences and the actual Since a deviation occurs in the crank angle, when a missing portion is included, the deviation in the number of occurrences caused by the missing is corrected so that the crank angle can be correctly detected from the number of occurrences.

Embodiments of the present invention will be described below.
FIG. 1 is a configuration diagram of a vehicle internal combustion engine 101 according to an embodiment. In the present embodiment, the internal combustion engine 101 is an in-line four-cylinder engine.
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.

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 catalytic converter 108 and the rear catalytic converter 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 intake side camshaft 134 and the exhaust side camshaft 110 rotate once for every two rotations of the crankshaft 120.

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 any known variable valve timing mechanism that changes the rotational phase of the camshaft relative to the crankshaft can be applied. No. 2003-184516, a variable valve timing mechanism provided with a movable guide part that is displaceably guided by a spiral guide, and a hydraulic vane type disclosed in Japanese Patent Application Laid-Open No. 2007-120406 A variable valve timing mechanism and a motor-type variable valve timing mechanism that is disclosed in Japanese Patent Application Laid-Open No. 2008-025541 and drives a camshaft by a motor may be used.

The ECU 114 has a built-in microcomputer, and controls the electronic control throttle 104, the variable valve timing mechanism 113, the fuel injection valve 131, and the like by arithmetically processing detection signals from various sensors according to a program stored in advance. .
The various sensors include an accelerator opening sensor 116 that detects the amount of depression of the accelerator pedal (accelerator opening), an air flow meter 115 that detects the intake air amount Q of the engine 101, and a detection signal according to the rotation of the crankshaft 120. A crank angle sensor 117 to output, a throttle sensor 118 to detect the opening TVO of the throttle valve 103b, a water temperature sensor 119 to detect the coolant temperature of the engine 101, and a detection signal according to the rotation of the intake camshaft 134. First and second cam sensors 132 and 133 are provided.

FIG. 3 shows the structure of the crank angle sensor 117 and the first and second cam sensors 132 and 133.
The crank angle sensor 117 is pivotally supported by the crankshaft 120 and has a signal plate 152 provided with a protruding portion 151 as a detected portion around it, and a pickup 153 that is fixed to the engine 101 side and detects the protruding portion 151. It consists of.

The protrusions 151 of the signal plate 152 are basically provided at equal intervals with a crank angle of 10 deg. However, the portion where the two protrusions 151 are continuously removed is located at the center of the crankshaft 120. It is provided at two places facing each other.
The number of protrusions 151 may be one, or three or more may be continuously deleted.

Then, the unit crank angle signal POS of the crank angle sensor 117, which is output as a pulse signal by shaping the output of the pickup 153, is continuously 16 pieces every 10 degrees in crank angle as shown in FIGS. In this case, 2 are missing and 16 consecutive outputs are repeated again.
Therefore, the crank angle from the first unit crank angle signal POS after the missing part to the first unit crank angle signal POS after the next missing part is 180 deg., And the crank angle 180 deg in the four-cylinder engine 101 of the present embodiment. This corresponds to the stroke phase difference (ignition interval) between the cylinders.

On the other hand, the first cam sensor 132 is pivotally supported at the end of the intake side camshaft 134 opposite to the end where the variable valve timing mechanism 113 is provided, and a projection 154 as a detected portion is provided around the first cam sensor 132. The signal plate 155 includes a pickup 156 that is fixed to the engine 101 side and detects the protrusion 154.
The protrusions 154 of the signal plate 155 are provided at equal intervals with a crank angle of 30 deg (cam angle of 15 deg), and no missing portion is provided.

The first cam angle signal CAM1 of the first cam sensor 132, which is output as a pulse signal by shaping the output of the pickup 156, is 30 deg (cam angle) as shown in FIGS. 15 deg) and output with a constant period.
The second cam sensor 133 is pivotally supported at the end of the intake side camshaft 134 opposite to the end where the variable valve timing mechanism 113 is provided, and a projection 157 as a detected portion is provided around the second cam sensor 133. The signal plate 158 includes a pickup 159 that is fixed to the engine 101 side and detects the protrusion 157.

The projections 157 of the signal plate 158 are provided as one, three, four, and two every 90 degrees in cam angle. In a portion where a plurality are provided continuously, the pitch of the protrusions 157 is set to 30 deg in crank angle (15 deg in cam angle), which is the same as the first cam angle signal CAM1.
The second cam angle signal CAM2 of the second cam sensor 133, which is output as a pulse signal by shaping the output of the pickup 159, is 90 deg (crank angle) as shown in FIGS. Every 180 deg), one is output in a single, 3 continuous, 4 continuous, 2 continuous state.

The number of second cam angle signals CAM2 to be output every 180 deg at the crank angle indicates a cylinder number. In the four-cylinder engine 101 of the present embodiment, the stroke phase difference between the cylinders is determined by the crank number. The angle is 180 deg, and the ignition order corresponds to # 1 cylinder → # 3 cylinder → # 4 cylinder → # 2 cylinder.
That is, in the four-cylinder engine 101 of the present embodiment, the piston of each cylinder becomes top dead center (compression top dead center or intake top dead center) every 180 degrees in crank angle, and 1 before the top dead center of the # 1 cylinder. Single second cam angle signal CAM2 is output, three consecutive second cam angle signals CAM2 are output before the top dead center of the # 3 cylinder, and four consecutive second cam angle signals CAM2 are output before the top dead center of the # 4 cylinder. Two cam angle signals CAM2 are output, and two consecutive second cam angle signals CAM2 are output before the top dead center of the # 2 cylinder.

Accordingly, by determining how many second cam angle signals CAM2 have been output, it is possible to determine the cylinder whose piston position will be the top dead center next, and based on the result of this cylinder determination, fuel injection and ignition The cylinder to be subjected to the detection is detected, and the injection pulse signal and the ignition signal are output based on the detection result.
Here, the first cam angle signal CAM1 and the second cam angle signal CAM2 maintain a constant phase relationship, but the phase relationship between the unit crank angle signal POS and the first and second cam angle signals CAM1, CAM2 is The variable valve timing mechanism 113 changes when the rotational phase of the intake camshaft 134 with respect to the crankshaft 120 is changed.

In the control of the variable valve timing mechanism 113, the actual rotational phase is detected, and the target rotational phase is calculated based on the engine operating state (engine load, engine rotational speed, etc.). The operation amount of the electromagnetic retarder 24 is feedback-controlled by a proportional / integral / differential operation based on a deviation from the rotational phase.
Hereinafter, details of rotational phase detection using the crank angle sensor 117, the first cam sensor 132, and the second cam sensor 133 will be described.

The flowchart of FIG. 4 is executed every time the first cam angle signal CAM1 is generated. First, in step S201, the counter CNT1 is incremented by 1 (see FIG. 8).
In step 202, it is determined whether or not the counter CNT1 is 3. If CNT1 = 3, the process proceeds to step S203, and if not CNT1 = 3, the process bypasses step S203 and proceeds to step S204.

In step S203, as will be described later, a counter CNT2 that is incremented by 1 every time the second cam angle signal CAM2 is generated is reset to zero (see FIG. 8).
In step S204, it is determined whether or not the counter CNT1 is 2. If not CNT1 = 2, the process proceeds to step S205, and the counter CNTCAM is incremented by 1.
On the other hand, if CNT1 = 2, the process proceeds to step S206 to reset the counter CNTCAM to zero, and the process proceeds to step S207 (cylinder discrimination means), and the value of the counter CNT2 at that time is set to the counter CYLCAM (cylinder Is set to (discrimination value) (see FIG. 8).

After step S205 or step S207, the process proceeds to step S208 to calculate the rotational phase of the intake side camshaft 134 with respect to the crankshaft 120. Details of the processing here will be described later based on the flowchart of FIG.
The flowchart of FIG. 5 is executed every time the second cam angle signal CAM2 is generated. In step S301, the counter CNT2 is incremented by 1, and in step S302, the counter CNT1 is reset to zero ( (See FIG. 8).

  The counter CNTCAM is incremented by 1 every time the first cam angle signal CAM1 is generated, and becomes a value that is reset to zero every 180 degrees in crank angle, and the timing at which the counter CNTCAM is reset to zero is regarded as a reference cam angle position. Furthermore, it is possible to specify the number of the first cam angle signal CAM1 from the reference cam angle position from the value of the counter CNTCAM.

The counter CYLCAM indicates a cylinder discrimination result that is changed every 180 degrees in crank angle. By comparing the counter CYLCAM with the counter CNTCAM, the latest first cam angle signal CAM1 is obtained from the intake camshaft 134. Can be specified as one of all the first cam angle signals CAM1 output during one rotation.
The flowchart of FIG. 6 is executed every time the unit crank angle signal POS is generated. In step S401, the generation cycle TPOS of the unit crank angle signal POS is measured.

In step S402, based on the ratio between the previous value and the current value of the period TPOS, it is determined whether or not the current period TPOS is a result of measuring a missing portion of the unit crank angle signal POS.
In the missing part of the unit crank angle signal POS, the time required to rotate by 30 deg at the crank angle is measured as the period TPOS. On the other hand, the crank angle is rotated by 10 deg at the part other than the missing part. Since the time required is measured as the period TPOS, the two show a large gap beyond the difference due to the normal rotation fluctuation.

Therefore, based on the ratio between the previous value and the current value of the period TPOS, it can be determined whether or not the current period TPOS is a result of measuring the missing portion of the unit crank angle signal POS.
If it is determined in step S402 that the current cycle TPOS is not a missing portion of the unit crank angle signal POS but a cycle of a crank angle of 10 deg, the process proceeds to step S403.

In step S403, the counter CNTCRA is incremented by 1, and in the next step S404, the cylinder-specific counters CNTnCYL (n = 1 to 4) are incremented by 1 (see FIG. 9).
On the other hand, if it is determined in step S402 that the current cycle TPOS is the result of measuring the missing portion of the unit crank angle signal POS, the process proceeds to step S405.

In step S405, the counter CNTCRA, which has been incremented by 1 every time the unit crank angle signal POS is generated, is reset to zero. In the next step S406 (reference crank angle position detecting means), the reference angle position signal ( Reference crank angle position signal) VTCREF is generated (see FIG. 9).
The reference angular position signal VTCREF is output every missing portion of the unit crank angle signal POS, that is, every 180 degrees in crank angle, and the counter CNTCRA is reset to zero at the output timing of the reference angular position signal VTCREF. .

In step S407, the value of the counter CYLCAM (cylinder discrimination value) at that time is set in CYLCNT (see FIG. 9).
In step S408, it is determined whether or not the value of the counter CYLCNT is 1, in other words, whether or not the # 1 cylinder next becomes top dead center.
If CYLCNT = 1, the process proceeds to step S409, where the counter CNT1CYL of the unit crank angle signal POS corresponding to the # 1 cylinder is reset to zero, and in the next step S410, counters CNTnCYL for each cylinder other than the counter CNT1CYL (N = 2 to 4) is increased by 1.

  Similarly, in steps S411 to S413, when CYLCNT = 3, the counter CNT3CYL is reset to zero, and the cylinder-specific counters CNTnCYL (n = 1, 2, 4) other than the counter CNT3CYL are incremented by one. In steps S414 to S416, when CYLCNT = 4, the counter CNT4CYL is reset to zero, and the cylinder counters CNTnCYL (n = 1 to 3) other than the counter CNT4CYL are incremented by one.

If it is determined in step S414 that CYLCNT = 4 is not satisfied, it is determined that CYLCNT = 2. In step S417, the counter CNT2CYL is reset to zero. In step S418, the counters CNTnCYL for each cylinder other than the counter CNT2CYL are reset. (N = 1, 3, 4) is increased by 1.
By the above processing, the cylinder counter CNTnCYL resets only the counter CNTnCYL of the nth cylinder to zero when CYLCNT = n, and is incremented by 1 every time the unit crank angle signal POS is generated. (See FIG. 9).

In other words, the cylinder-by-cylinder counter CNTnCYL is incremented by 1 every time the unit crank angle signal POS is generated, and is reset to zero every time the crankshaft 120 rotates twice. The reset timing of each counter CNTnCYL is: The crank angle is shifted by 180 degrees.
Next, the calculation of the rotation phase (cam phase detection means) in step S208 will be described in detail based on the flowchart of FIG.

In step S501, a time VTCTIM from the unit crank angle signal POS output immediately before to the current first cam angle signal CAM1 is obtained (see FIG. 10).
In the time VTCTIM, the value of the counter counted up every minute unit time is updated and stored every time the unit crank angle signal POS is generated, and the stored value and the counter at the present time (when the first cam angle signal CAM1 is generated) are stored. It can be obtained from the difference from the value.

In step S502, data of the period TPOS of the unit crank angle signal POS measured recently is read.
In step S503, it is determined whether or not the value of the counter CYLCAM is 1. If CYLCAM = 1, the process proceeds to step S504.
In step S504, it is determined whether or not the value of the counter CNT2CYL for each cylinder is 15 or less, and the expression used for calculating the rotational phase VTCANGL is switched between CNT2CYL ≦ 15 and CNT2CYL> 15. To.

When CNT2CYL ≦ 15, the process proceeds to step S505, and the rotational phase VTCANGL is calculated as VTCANGL = (CNT2CYL + VTCTIM / TREF10) × 10−CNTCAM × 30 [deg].
On the other hand, if CNT2CYL> 15, the process proceeds to step S506, and the rotational phase VTCANGL is calculated as VTCANGL = (CNT2CYL + 2 + VTCTIM / TREF10) × 10−CNTCAM × 30 [deg].

  The TREF10 is a time required for the crankshaft 120 to rotate by 10 deg. If the period TPOS is obtained by measuring the period of the POS signal output at intervals of 10 deg, TREF10 = TPOS, and the period TPOS is If it is a result of measuring the missing portion of the POS signal, the period TPOS is the time required for the crankshaft 120 to rotate by 30 degrees, and therefore TREF10 = TPOS / 3 (see FIG. 10).

Whether or not the period TPOS is a result of measuring a missing portion of the POS signal can be determined based on whether or not the reference angular position signal VTCREF is generated.
The CNT2CYL indicates the number of POS signals generated from the generation time of the reference angular position signal VTCREF to the latest first cam angle signal CAM1, and VTCTIM / TREF10 indicates the latest first cam angle signal from the latest POS signal. It indicates how many 10 deg cycles the time until CAM1 is, and by multiplying CNT2CYL + VTCTIM / TREF10 by 10, from the timing when CNT2CYL is reset to zero to the current first cam angle signal CAM1 This indicates the crank angle.

However, if the POS signal is missing in the middle of counting up to the present time, the value of CNT2CYL does not correctly indicate the crank rotation angle so far.
Therefore, by determining whether or not CNT2CYL ≦ 15, it is determined whether or not CNT2CYL is counted up including the missing portion of the POS signal. In such a case, 2 is added to CNT2CYL in association with counting up two extra CNT2CYLs (see C in FIG. 10).

  Here, (CNT2CYL + VTCTIM / TREF10) × 10 or (CNT2CYL + 2 + VTCTIM / TREF10) × 10 indicates an angle from the reference angle position of the crankshaft 120 to the latest first cam angle signal CAM1, but the first cam angle signal CAM1 is Unless specified, the rotational phase of the intake camshaft 134 relative to the crankshaft 120 cannot be determined.

On the other hand, the value of the counter CNTCAM is a value indicating the number of the first cam angle signal CAM1 from the reference cam angle position as described above, and is counted up every 30 degrees in the crank angle. X30 indicates the rotation angle from the reference cam angle position to the current first cam angle signal CAM1.
Therefore, by subtracting CNTCAM × 30 from (CNT2CYL + VTCTIM / TREF10) × 10 or (CNT2CYL + 2 + VTCTIM / TREF10) × 10, the crank angle from the reference angle position of the crankshaft 120 to the reference angle position of the intake camshaft 134 is increased. This is unchanged if the rotational phase of the intake camshaft 134 with respect to the crankshaft 120 is constant, and is a value that changes as the rotational phase changes.

  Similarly, when the value of the counter CYLCAM is 3, a distinction is made between CNT1CYL ≦ 15 and CNT1CYL> 15 (step S507 → step S508). When CNT1CYL ≦ 15, VTCANGL = (CNT1CYL + VTCTIM / The rotational phase is calculated based on TREF10) × 10−CNTCAM × 30 [deg] (step S509). When CNT1CYL> 15, based on VTCANGL = (CNT1CYL + 2 + VTCTIM / TREF10) × 10−CNTCAM × 30 [deg] A rotational phase is calculated (step S510).

  When the value of the counter CYLCAM is 4, a distinction is made between CNT3CYL ≦ 15 and CNT3CYL> 15 (step S511 → step S512). When CNT3YL ≦ 15, VTCANGL = (CNT3CYL + VTCTIM / TREF10) The rotation phase is calculated based on × 10−CNTCAM × 30 [deg] (step S513). When CNT3CYL> 15, the rotation phase is calculated based on VTCANGL = (CNT3CYL + 2 + VTCTIM / TREF10) × 10−CNTCAM × 30 [deg]. Is calculated (step S514).

  Further, when it is determined in step S511 that CYLCAM = 4, it is determined that CYLCAM = 2, and in step S515, a distinction is made between CNT4CYL ≦ 15 and CNT4CYL> 15. When CNT4YL ≦ 15, VTCANGL = (CNT4CYL + VTCTIM / TREF10) × 10−CNTCAM × 30 [deg] (step S516) When CNT4CYL> 15, VTCANGL = (CNT4CYL + 2 + VTCTIM / TREF10) × 10−CNTCAM × 30 [deg] ] To calculate the rotational phase (step S517).

As a result of the above calculation process, the VTCANGL indicating the rotation phase of the intake camshaft 134 with respect to the crankshaft 120 is calculated every 30 degrees in terms of crank angle. The phase can be detected, and the cylinder can be determined based on the second cam angle signal CAM2.
For example, if the angle until the second cam angle signal CAM2 is output for the first time after the generation of the reference angle position signal VTCREF is measured as data indicating the rotation phase, the detection result of the rotation phase at every 180 deg of the crank angle. In particular, when the engine speed is low, the period in which the detection result of the rotational phase is updated becomes long, and the variable valve timing mechanism 113 cannot be feedback-controlled with high speed and high accuracy.

The second cam angle signal CAM2 is a signal for cylinder discrimination. In the four-cylinder engine of this embodiment, cylinder discrimination is performed every 180 degrees, so that the rotation phase is detected using the cylinder discrimination signal. As a result, the rotation phase update cycle is constrained by the cylinder discrimination cycle.
That is, when the rotation phase is detected using the cylinder discrimination signal, the rotation phase is detected every 180 degrees in terms of crank angle. For example, once in 50 ms during idling when the engine rotation speed is 600 rpm. Only the rotational phase can be detected.

  In recent years, the operating range in which the rotational phase of the camshaft is controlled by the variable valve timing mechanism tends to expand to the low rotational side, but if the detection cycle in the low rotational range is long as described above, the target rotational phase is reached. On the other hand, it is difficult to converge the rotational phase of the implementation without overshooting and with good response, and this is a factor that hinders the expansion of the rotational phase control range to the low rotational range.

Here, in order to shorten the detection period of the rotation phase in the low rotation range, for example, the number of cam signals output per one rotation of the camshaft is increased, and at the same interval as the generation interval of this cam signal, When the reference crank angle position is set, if the conversion angle of the rotational phase of the camshaft is large, there arises a problem that the rotational phase is erroneously detected.
That is, when the angle from the reference crank angle position to the immediately following cam signal is measured, when the rotational phase of the camshaft is advanced, the angle from the reference crank angle position to the immediately following cam signal becomes shorter. When the cam signal generation position is advanced beyond the reference crank angle position, the cam signal output immediately after the reference crank angle position is changed to a cam signal delayed by one cycle from the previous cam signal. In other words, it is detected as a retarded state although it is actually advanced greatly.

  In contrast, in the present embodiment, in addition to the sensor 133 that outputs the second cam angle signal CAM2 as the cylinder discrimination signal, a sensor 132 that outputs the first cam angle signal CAM1 for each unit cam angle is provided. By identifying the first cam angle signal CAM1 based on the second cam angle signal CAM2 while performing cylinder discrimination based on the two cam angle signal CAM2, the rotational phase for each occurrence of the first cam angle signal CAM1 is determined. It is possible to detect.

Therefore, the rotation phase can be detected every time the first cam angle signal CAM1 is generated, and the detection result of the rotation phase can be updated in a sufficiently short period even at the time of low rotation. The mechanism 113 can be feedback controlled with high speed and high accuracy.
Although the generation period of the first cam angle signal CAM1 can be set to an angle smaller than 30 deg in crank angle, it can be limited to a necessary and sufficient update period by setting it to 30 deg. It is clear that the period is set and is not limited to the 30 deg period.

In this embodiment, the internal combustion engine 101 is a four-cylinder engine. However, the present invention can be applied to a six-cylinder engine having a stroke phase difference of 120 degrees between cylinders, and the number of cylinders is not limited.
Furthermore, in the second cam angle signal CAM2 used for cylinder discrimination, in this embodiment, the cylinder number is indicated by the number of generated pulses. However, for example, the cylinder number can be indicated by a difference in pulse width.

Further, a unit crank angle sensor that outputs the unit crank angle signal POS every 10 degrees without omission and a reference crank angle sensor that generates the reference angular position signal VTCREF can be provided.
When cylinder discrimination using the first and second cam sensors 132 and 133 is unnecessary, for example, the second cam angle signal is output once per rotation of the camshaft, for example, and the second cam By counting the number of occurrences of the first cam angle signal from the time when the angle signal is generated, the first cam angle signal can be individually specified and used for detecting the rotational phase.

  Further, in the above embodiment, as shown in FIG. 3, the first and second cam sensors 132 and 133 are provided at the end of the camshaft 134 opposite to the side where the variable valve timing mechanism 113 is provided. However, one cam sensor can be installed at the end on the side where the variable valve timing mechanism 113 is provided, and the other cam sensor can be arranged at the end opposite to the side where the variable valve timing mechanism 113 is provided. .

As described above, if the first cam sensor 132 is provided at one end of the camshaft 134 and the second cam sensor 133 is provided at the other end, the layout of the first and second cam sensors 132 and 133 on the engine can be facilitated. Yes.
Further, as means for performing cylinder discrimination based on the second cam angle signal CAM2 from the second cam sensor 133, there are the following means.

FIGS. 11 to 13 output a second cam angle signal at which the signal level at the reference angular position (two missing positions of the unit crank angle signal POS) switches between high and low every time the crankshaft 120 makes one rotation. Thus, an embodiment in which the reference cam angle position is detected while performing cylinder discrimination will be described.
A cam sensor 133 shown in FIG. 11 includes a signal plate 701 that is pivotally supported by a camshaft 134 and a pickup 702 that is fixed to the engine 101 side and detects the proximity of a detected portion of the signal plate 701.

  The signal plate 701 has a 180 deg range that is larger in diameter than the remaining 180 deg range, and has a projection 703 (detected portion) that is continuous in the 180 deg range, and is output from the pickup 702. The second cam angle signal CAM2 is a signal that switches between high and low every time the camshaft 134 rotates halfway (every crankshaft 120 makes one rotation).

Further, as shown in FIG. 12, the rising position of the second cam angle signal CAM2 is aligned with the top dead center of the # 2 cylinder, and the falling position of the second cam angle signal CAM2 is set to that of the # 3 cylinder. Aligned with top dead center.
On the other hand, the crank angle sensor 117 includes a signal plate 751 having a shape as shown in FIG. 13 and a pickup 752 that is fixed to the engine 101 side and detects the proximity of the detected portion of the signal plate 751.

The protrusions 753 of the signal plate 751 are basically provided at equal intervals with a crank angle of 10 deg, but one portion where the two protrusions 753 are continuously missing is provided.
In other words, the crank angle sensor 117 shown in FIG. 3 is set so that the unit crank angle signal POS is lost every time the crankshaft 120 rotates 180 degrees (the generation interval of the unit crank angle signal POS becomes longer). The crank angle sensor 117 shown in FIG. 13 is set so that the unit crank angle signal POS is lost every time the crankshaft 120 rotates once (the generation interval of the unit crank angle signal POS becomes longer).

Further, as shown in FIG. 12, the position where the unit crank angle signal POS is missing is set before the top dead center of the # 1 cylinder and the # 4 cylinder.
Therefore, in the reference angular position signal VTCREF (the missing portion of the unit crank angle signal POS) before the top dead center of the # 1 cylinder, the second cam angle signal CAM2 is at a high level, and the reference before the top dead center of the # 4 cylinder is reached. In the angular position signal VTCREF (the missing portion of the unit crank angle signal POS), the second cam angle signal CAM2 is at a low level.

In other words, the reference angular position signal VTCREF per rotation of the crankshaft 120 is output once, and the signal level of the second cam angle signal CAM2 at the time of generation of the reference angular position signal VTCREF is one rotation of the crankshaft 120. Each time you switch between high and low.
Therefore, at the time when the reference angular position signal VTCREF is generated (the missing portion of the unit crank angle signal POS), the # 1 cylinder and the # 4 cylinder depend on whether the signal level of the second cam angle signal CAM2 is high or low. It is possible to determine which of these is top dead center.

Then, when the crank angle is rotated by 180 deg from the cylinder discrimination timing, the current cylinder can be discriminated from the previous cylinder discrimination result, and the top dead center of the # 1 cylinder is detected when the previous reference angle position signal VTCREF is generated. In that case, it is determined that the top dead center at the point of rotation by 180 deg is # 3 cylinder.
Further, when the top dead center of the # 4 cylinder is detected at the time when the previous reference angular position signal VTCREF is generated, it is determined that the top dead center is the # 2 cylinder when the cylinder is further rotated by 180 deg.

Therefore, by determining whether the signal level of the second cam angle signal CAM2 is high or low at the time of generation of the reference angular position signal VTCREF (the missing portion of the unit crank angle signal POS), the # 1 cylinder to All top dead centers of # 4 cylinder can be detected.
The first cam angle signal CAM1 is identified based on the second cam angle signal CAM2, as shown in FIG. 12, for example, with reference to the trailing edge of the second cam angle signal CAM2, the first cam input thereafter This can be done by assigning a number to the angle signal CAM1 (counting the first cam angle signal CAM1).

  That is, assuming that the first cam angle signal CAM1 has a cam angle of 30 deg, the cam angle can be detected at a 30 deg pitch on the basis of the fall of the second cam angle signal CAM2 (# 3 cylinder top dead center). Thus, as in the above embodiment, the time VTCTIM from the unit crank angle signal POS output immediately before to the first cam angle signal CAM1 is obtained (see FIG. 10), so that each time the first cam angle signal CAM1 is generated. The rotational phase can be detected.

A number is assigned to the first cam angle signal CAM1 input thereafter (counting the first cam angle signal CAM1) with reference to the rise of the second cam angle signal CAM2 (top dead center of the # 2 cylinder). Can do.
Therefore, even in the configuration using the second cam sensor 133 and the crank angle sensor 117 shown in FIGS. 11 and 13, the detection result of the rotational phase can be updated with a sufficiently short period, and the variable valve timing mechanism 113 can be operated at high speed.・ Highly accurate feedback control.

Further, the signal form of the second cam angle signal CAM2 is simplified as compared with the case where the cylinder is discriminated by the number of pulses, the calculation processing is facilitated, and necessary and sufficient detection is possible even when the diameter of the signal plate 701 is relatively small. Therefore, the cam sensor 133 can be downsized, and the layout on the engine is facilitated.
Further, as the second cam angle sensor 133 combined with the crank angle sensor 117 shown in FIG. 13, a cam angle sensor having the configuration shown in FIG. 14 can be used.

The second cam angle sensor 133 shown in FIG. 14 is pivotally supported by the camshaft 134 and is fixed to the engine 101 side with a signal plate 782 provided with a protruding portion 781 as a detected portion at one location on the periphery. The signal plate 782 includes a pickup 783 that detects the proximity of the detected portion (protrusion 781).
Therefore, as shown in FIG. 15, the second cam angle sensor 133 outputs one pulse of the second cam angle signal CAM2 for two rotations of the crankshaft 120, and the output position of the second cam angle signal CAM2 is It is set immediately before the missing portion of the unit crank angle signal POS.

  In other words, the unit crank angle signal POS is lost both before the top dead center of the # 1 cylinder and before the top dead center of the # 4 cylinder, but immediately before the missing portion of the unit crank angle signal POS, The 2-cam angle signal CAM2 is output only when the top dead center of the # 1 cylinder is before the top dead center. When the unit crank angle signal POS before the top dead center of the # 4 cylinder is missing, The second cam angle signal CAM2 is not output immediately before.

Therefore, if the second cam angle signal CAM2 is output immediately before the missing part of the unit crank angle signal POS, the missing part this time is before the top dead center of the # 1 cylinder. If the second cam angle signal CAM2 is not output immediately before the missing portion of the crank angle signal POS, the missing portion this time is before the top dead center of the # 4 cylinder.
Furthermore, the top dead center at the time when the unit crank angle signal POS is rotated by 180 deg from the missing portion of the unit crank angle signal POS (when the reference angular position signal VTCREF is generated) can be determined based on the determination result at the missing portion. When # 1 cylinder top dead center is detected in the missing part, it is determined that the top dead center is # 3 cylinder when it is rotated by 180deg, and # 4 cylinder top dead center is detected in the previous missing part. In this case, it is determined that the top dead center is the # 2 cylinder when it is rotated by 180 deg.

Therefore, by determining whether or not the second cam angle signal CAM2 is output immediately before the missing portion of the unit crank angle signal POS (when the reference angular position signal VTCREF is generated), the # 1 cylinder to the # 4 cylinder All the top dead centers can be detected.
Further, the first cam angle signal CAM1 is identified based on the second cam angle signal CAM2, as shown in FIG. 15, for example, with reference to the trailing edge of the second cam angle signal CAM2, the first cam input thereafter This can be done by assigning a number to the angle signal CAM1 (counting the first cam angle signal CAM1).

  That is, if the first cam angle signal CAM1 is a cam angle of 30 deg pitch, the cam angle can be detected at a 30 deg pitch with reference to the falling edge of the second cam angle signal CAM2, as in the above embodiment. By obtaining the time VTCTIM from the unit crank angle signal POS output immediately before to the first cam angle signal CAM1 (see FIG. 10), the rotation phase can be detected every time the first cam angle signal CAM1 is generated.

The first cam angle signal CAM1 input thereafter can be numbered (counting the first cam angle signal CAM1) with reference to the rising edge of the second cam angle signal CAM2.
Therefore, even in the configuration using the second cam sensor 133 and the crank angle sensor 117 shown in FIG. 14 and FIG. 13, the detection result of the rotational phase can be updated with a sufficiently short cycle, and the variable valve timing mechanism 113 can be operated at high speed.・ Highly accurate feedback control.

Furthermore, the signal form of the second cam angle signal is simplified as compared with the case where the cylinder is discriminated by the number of pulses, the arithmetic processing is facilitated, and necessary and sufficient detection is possible even when the diameter of the signal plate 782 is relatively small. Since it becomes possible, the cam sensor 133 can be reduced in size, and the layout to an engine becomes easy.
Note that the output position of the second cam angle signal CAM2 is not limited to immediately before the missing portion. For example, when the missing portion of the unit crank angle signal POS is detected, it is determined whether or not the second cam angle signal CAM2 has been output in one rotation of the crankshaft 120 so far, thereby performing cylinder discrimination. Thus, it is not necessary to limit the generation position of the second cam angle signal CAM2.

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 figure which shows the structure of the crank angle sensor and 1st, 2nd cam sensor in embodiment. The flowchart which shows the process performed whenever the 1st cam angle signal CAM1 generate | occur | produces in embodiment. The flowchart which shows the process performed whenever the 2nd cam angle signal CAM2 generate | occur | produces in embodiment. 6 is a flowchart illustrating processing performed every time a unit crank angle signal POS is generated in the embodiment. 5 is a flowchart showing details of a rotational phase calculation process performed every time the first cam angle signal CAM1 is generated in the embodiment. 4 is a time chart showing the correlation between various signals POS, CAM1, CAM2 and various counters CNT1, CNT2, CYLCAM, CNTCAM in the embodiment. 4 is a time chart showing the correlation between various signals POS, CAM1, and CAM2 and various counters CNTCRA, CYLCAM, CYLCNT, and CNTnCYL in the embodiment. The time chart for demonstrating the calculation process of the rotation phase in embodiment. The figure which shows another structure of the 2nd cam angle sensor in embodiment. 14 is a time chart showing the correlation between the second cam angle signal CAM2 output from the second cam angle sensor of FIG. 11 and the unit crank angle signal POS output from the crank angle sensor of FIG. The figure which shows another structure of the crank angle sensor in embodiment. The figure which shows another structure of the 2nd cam angle sensor in embodiment. 14 is a time chart showing the correlation between the second cam angle signal CAM2 output from the second cam angle sensor of FIG. 14 and the unit crank angle signal POS output from the crank angle sensor of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Internal combustion engine, 105 ... Intake valve, 113 ... Variable valve timing mechanism, 114 ... Engine control unit (ECU), 117 ... Crank angle sensor, 120 ... Crankshaft, 132 ... First cam sensor 132, 133 ... Second cam sensor, 134 ... Camshaft

Claims (8)

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,
A first cam sensor that outputs a first cam angle signal each time the camshaft rotates by a unit angle;
A second cam sensor that outputs a second cam angle signal for discriminating a cylinder at a specific piston position at a reference cam angle position for each phase difference between strokes ;
Cylinder discrimination means for discriminating a cylinder at a specific piston position based on the second cam angle signal;
Reference crank angle position detecting means for detecting a reference crank angle position of the crankshaft;
The first cam angle signal is identified based on the number of occurrences of the first cam angle signal from the reference cam angle position identified by the second cam angle signal and the discrimination result of the cylinder, and the first cam is identified. Cam phase detection means for detecting the rotational phase based on a phase difference between a cam angle signal and the reference crank angle position;
A cam phase detection device for an internal combustion engine, comprising: First counting means for counting up the value of the first counter every time the first cam angle signal is output, and resetting the value of the first counter at each update timing of the cylinder discrimination result by the cylinder discrimination means; In addition,
2. The cam phase of the internal combustion engine according to claim 1, wherein the cam phase detection means identifies the first cam angle signal output most recently from the discrimination result of the cylinder and the value of the first counter. Detection device. The second cam sensor outputs a second cam angle signal having a different number for each phase difference between strokes between cylinders, and
Second counting means for counting up the value of the second counter each time the first cam angle signal is output, and resetting the value of the second counter each time the second cam angle signal is output;
Every time the second cam angle signal is output, the value of the third counter is counted up, and the value of the third counter is reset when the value of the second counter reaches the first set value. Means, provision,
3. The internal combustion engine according to claim 2, wherein the cylinder discriminating unit updates the discrimination result of the cylinder based on the value of the third counter when the value of the second counter reaches the second set value . Cam phase detector. 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,
Reference crank angle position detecting means for detecting one reference crank angle position per rotation of the crankshaft;
A first cam sensor that outputs a first cam angle signal each time the camshaft rotates by a unit angle;
A second cam sensor that outputs a second cam angle signal that switches between high and low each time the camshaft makes a half rotation;
The first cam angle signal is identified based on the number of occurrences of the first cam angle signal from the reference cam angle position identified by the high / low switching of the second cam angle signal, and the first cam is identified. Cam phase detection means for detecting the rotational phase based on a phase difference between a cam angle signal and the reference crank angle position;
A cam phase detection device for an internal combustion engine, comprising: The cam phase detection means discriminates the first cam angle signal by counting the first cam angle signal output thereafter with reference to the rising or falling edge of the second cam angle signal. 5. The cam phase detection device for an internal combustion engine according to claim 4, wherein: While the cam phase detecting means detects a crank angle from the reference crank angle position to the latest first cam angle signal, from the number of the first cam angle signals generated and the angle pitch of the first cam angle signal A crank angle from the reference cam angle position to the latest first cam angle signal is calculated, and from the crank angle from the reference crank angle position to the latest first cam angle signal, the latest first cam angle signal from the reference cam angle position is calculated. The phase difference between the reference crank angle position and the reference cam angle position is calculated every time the first cam angle signal is generated by subtracting the crank angle up to the cam angle signal. The cam phase detection device for an internal combustion engine according to any one of 5 . The reference crank angle position detecting means;
A unit crank angle signal is output each time the crankshaft rotates by a unit angle, and the unit crank angle signal is provided with a crank angle sensor that is missing at at least one location per rotation of the crankshaft,
7. The internal combustion engine according to claim 1, wherein a portion where the unit crank angle signal is missing is detected, and the reference crank angle position is detected based on the detected missing portion . Cam phase detector. The cam phase detection means detects the crank angle from the reference crank angle position to the latest first cam angle signal based on the number of occurrences of the unit crank angle signal, and detects the latest first crank angle signal from the reference crank angle position. 8. The cam phase detection apparatus for an internal combustion engine according to claim 7, wherein the number of occurrences is corrected based on whether or not the missing portion is included in one cam angle signal .

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