JP4298535B2 - Variable valve controller for internal combustion engine - Google Patents

Description

  The present invention relates to a variable valve control apparatus for an internal combustion engine that controls at least a variable center phase of an operating angle of an engine valve.

Patent Document 1 discloses a variable valve twing mechanism that varies the center phase of the operating angle of the engine valve by changing the rotational phase of the camshaft with respect to the crankshaft, and the reference of the crankshaft and camshaft. A configuration is disclosed in which the center phase is detected based on a rotation position detection signal.
JP 2000-297686 A

Incidentally, as described above, in the configuration in which the center phase of the engine valve is detected based on the detection signal of the reference rotational position of the crankshaft and the camshaft, the center phase is detected at every constant crank angle.
For this reason, at the time of low rotation, the center phase detection cycle becomes longer than the control execution cycle using the detection result of the center phase, and as a result, the control is performed based on the center phase different from the actual while the center phase is updated. Will be done.

  For example, a variable valve timing mechanism that makes the center phase of the intake valve operating angle variable by changing the rotational phase of the camshaft with respect to the crankshaft, and variable operation that makes the valve lift amount and operating angle of the intake valve variable. In order to limit the opening and closing timing of the intake valve within the limits based on the requirements such as the cylinder residual gas amount and the effective exhaust amount, the operating angle is changed according to the change of the center phase by the variable valve timing mechanism. Need to be controlled.

However, as described above, when the detection period of the center phase becomes longer, it is determined whether the opening / closing timing limit is exceeded based on a value different from the actual center phase. There is a problem that the operating angle may exceed the limit.
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is capable of controlling the opening characteristics of an engine valve in response to an operation request even when the detection period of the center phase of the operating angle is long. The purpose is to provide.

Therefore, according to the first aspect of the present invention, the variable valve timing mechanism that varies the center phase of the engine valve operating angle by changing the rotational phase of the camshaft relative to the crankshaft, and the engine valve operating angle is variable. In a variable valve control apparatus for an internal combustion engine having a variable valve mechanism, the center phase is detected based on a detection signal of a reference rotational position of the crankshaft and camshaft, and the center phase based on the detection signal is detected. Estimates changes in the center phase during the detection cycle, and sets the maximum value of the engine valve operating angle based on the center phase detected based on the detection signal of the reference rotational position and the estimated value of the center phase The target of the operating angle in the variable valve mechanism is limited to the maximum value or less .

According to such a configuration, since the detection of the center phase based on the detection signal of the reference rotational position of the crankshaft and the camshaft is performed at every constant crank angle , the detection cycle of the center phase based on the detection signal is The change of the center phase is estimated between.
And setting the maximum value of the operating angle of the engine valve based on the detected value and the estimated value of the center phase, and limiting the target of the operating angle in the variable valve mechanism to the maximum value or less, Even if the detection of the center phase based on the detection signal of the reference rotation position of the camshaft is performed at every constant crank angle, the opening / closing timing of the engine valve exceeds the limit during that period , and the drivability is avoided.

In the invention according to claim 2 , the engine valve operating range is determined when the engine valve opening / closing timing is selected as a control parameter of either the center phase or the estimated value detected based on the detection signal of the reference rotational position. The maximum value of the operating angle is set so as to be within the limit value of the operating angle corresponding to .
According to this configuration, the maximum value of the operating angle is set so that the opening / closing timing of the engine valve does not exceed the limit value in both the center phase detected based on the detection signal of the reference rotational position and the estimated value .

Therefore, even if the detection of the center phase based on the detection signal of the reference rotational position of the crankshaft and camshaft is performed at every fixed crank angle, the operating angle is controlled so that the opening / closing timing of the engine valve exceeds the limit. Can be avoided.
According to a third aspect of the present invention, the opening timing of the engine valve does not exceed the advance angle limit based on the more advanced angle between the center phase detected based on the reference rotation position detection signal and the estimated value. As described above, the maximum value of the operating angle of the engine valve is set , and on the basis of the retarded angle between the center phase detected based on the detection signal of the reference rotational position and the estimated value, the engine valve The maximum value of the operating angle of the engine valve is set so that the closing timing does not exceed the retard limit.

According to such a configuration, the direction where the center phase detected based on the detection signal of the reference rotational position and the estimated value are more retarded, that is, the engine valve closing timing is judged to be closer to the retard limit. As a reference, it is determined whether or not the closing timing of the engine valve exceeds the retardation limit, and the more advanced one of the center phase and the estimated value detected based on the detection signal of the reference rotation position, that is, Based on the determination that the opening timing of the engine valve is closer to the advance angle limit, it is determined whether or not the opening timing of the engine valve exceeds the advance angle limit. Set the maximum operating angle of the engine valve so that the advance angle limit is not exceeded .

  Therefore, even if the detection of the center phase based on the detection signal of the reference rotational position of the crankshaft and the camshaft is performed at every constant crank angle, the opening timing of the engine valve exceeds the advance limit, It is possible to avoid that the closing timing of exceeds the retard limit.

FIG. 1 is a system configuration diagram of an internal combustion engine for a vehicle according to an 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 the internal combustion engine 101, and a combustion chamber 106 is connected via the electronic control throttle 104 and the intake valve 105. Air is inhaled inside.
The combustion exhaust is discharged from the combustion chamber 106 through the exhaust valve 107, purified by the front catalyst 108 and the rear catalyst 109, and then released into the atmosphere.

The exhaust valve 107 is driven to open and close by a cam 111 pivotally supported on the exhaust camshaft 110 while maintaining a constant valve lift, valve operating angle, and valve timing.
On the other hand, on the intake valve 105 side, a variable valve event and lift (VEL) mechanism 112 that continuously varies the valve lift amount of the intake valve 105 together with the operating angle is provided.
The VEL mechanism 112 corresponds to the variable valve mechanism in the present embodiment.

Further, on the intake valve 105 side, a VTC (Variable Valve Timing Control) mechanism 113 that continuously varies the center phase of the valve operating angle of the intake valve 105 by changing the rotational phase of the intake camshaft with respect to the crankshaft. Is provided.
The VTC mechanism 113 corresponds to the variable valve timing mechanism in the present embodiment.
The engine control unit (ECU) 114 incorporating the microcomputer controls the VEL mechanism 112 and the VTC mechanism 113 so as to obtain the required intake air amount corresponding to the required torque, the required cylinder residual gas rate, and the like. The electronic control throttle 104 is controlled so as to obtain a suction negative pressure.

  The ECU 114 includes an air flow meter 115 that detects the intake air amount of the internal combustion engine 101, an accelerator pedal sensor 116 that detects the accelerator opening, a crank angle sensor 117 that outputs a crank angle signal for each reference rotational position of the crankshaft 120, Detection signals from a throttle sensor 118 that detects the opening TVO of the throttle valve 103b, a water temperature sensor 119 that detects the coolant temperature of the internal combustion engine 101, and a cam sensor 132 that outputs a cam signal for each reference rotational position of the camshaft 13 are input. Is done.

Further, an electromagnetic fuel injection valve 131 is provided in the intake port 130 upstream of the intake valve 105 of each cylinder. The fuel injection valve 131 is driven to open by the injection pulse signal from the ECU 114, and the injection is performed. An amount of fuel proportional to the injection pulse width (valve opening time) of the pulse signal is injected.
2 to 4 show the structure of the VEL mechanism 112 in detail.

  The VEL mechanism 112 shown in FIGS. 2 to 4 includes a pair of intake valves 105, 105, a hollow camshaft 13 (drive shaft) rotatably supported by the cam bearing 14 of the cylinder head 11, and the camshaft Two eccentric cams 15 and 15 (drive cams), which are rotational cams supported by the shaft 13, a control shaft 16 rotatably supported by the same cam bearing 14 above the cam shaft 13, and the control shaft 16, a pair of rocker arms 18 and 18 supported by a control cam 17 so as to be swingable, and a pair of independent rockers disposed at upper ends of the intake valves 105 and 105 via valve lifters 19 and 19, respectively. The moving cams 20 and 20 are provided.

The eccentric cams 15 and 15 and the rocker arms 18 and 18 are linked by link arms 25 and 25, and the rocker arms 18 and 18 and the swing cams 20 and 20 are linked by link members 26 and 26.
The rocker arms 18, 18, the link arms 25, 25, and the link members 26, 26 constitute a transmission mechanism.

As shown in FIG. 5, the eccentric cam 15 has a substantially ring shape and includes a small-diameter cam main body 15a and a flange portion 15b integrally provided on the outer end surface of the cam main body 15a. A camshaft insertion hole 15 c is formed through the shaft, and the axis X of the cam body 15 a is eccentric from the axis Y of the camshaft 13 by a predetermined amount.
The eccentric cam 15 is press-fitted and fixed to the camshaft 13 on both outer sides that do not interfere with the valve lifter 19 via a cam shaft insertion hole 15c.

As shown in FIG. 4, the rocker arm 18 is bent in a substantially crank shape, and a central base 18 a is rotatably supported by the control cam 17.
A pin hole 18d into which a pin 21 connected to the tip end of the link arm 25 is press-fitted is formed at one end 18b protruding from the outer end of the base 18a, while the inner end of the base 18a is formed. A pin hole 18e into which a pin 28 connected to one end portion 26a (described later) of each link member 26 is press-fitted is formed in the other end portion 18c projecting from the portion.

The control cam 17 has a cylindrical shape, is fixed to the outer periphery of the control shaft 16, and the position of the axis P1 is eccentric from the axis P2 of the control shaft 16 by α as shown in FIG.
As shown in FIGS. 2, 6, and 7, the rocking cam 20 has a substantially horizontal U shape, and a cam shaft 13 is fitted into a substantially annular base end portion 22 so as to be rotatably supported. A support hole 22a is formed through, and a pin hole 23a is formed through the end 23 located on the other end 18c side of the rocker arm 18.

Further, a base circle surface 24a on the base end portion 22 side and a cam surface 24b extending in an arc shape from the base circle surface 24a toward the end edge side of the end portion 23 are formed on the lower surface of the swing cam 20. The circular surface 24 a and the cam surface 24 b come into contact with predetermined positions on the upper surfaces of the valve lifters 19 in accordance with the swing position of the swing cam 20.
That is, when viewed from the valve lift characteristics shown in FIG. 8, as shown in FIG. 2, the predetermined angle range θ1 of the base circle surface 24a becomes the base circle section, and the predetermined angle range θ2 from the base circle section θ1 of the cam surface 24b changes. This is a so-called ramp section, and further, a predetermined angle range θ3 from the ramp section θ2 of the cam surface 24b is set to be a lift section.

The link arm 25 includes an annular base portion 25a and a projecting end 25b projecting at a predetermined position on the outer peripheral surface of the base portion 25a. At the center position of the base portion 25a, the cam body of the eccentric cam 15 is provided. A fitting hole 25c is formed in the outer peripheral surface of 15a so as to be freely rotatable, and a pin hole 25d through which the pin 21 is rotatably inserted is formed in the protruding end 25b.
Further, the link member 26 is formed in a straight line having a predetermined length, and circular pin ends 26a and 26b have pin holes 18d in the other end 18c of the rocker arm 18 and the end 23 of the swing cam 20, respectively. , 23a, and pin insertion holes 26c and 26d through which end portions of the pins 28 and 29 are rotatably inserted are formed.

In addition, snap rings 30, 31, and 32 that restrict the axial movement of the link arm 25 and the link member 26 are provided at one end of each pin 21, 28, and 29.
In the above configuration, the valve lift amount changes as shown in FIGS. 6 and 7 depending on the positional relationship between the axis P2 of the control shaft 16 and the axis P1 of the control cam 17, and the control shaft 16 is rotated. By driving, the position of the axis P2 of the control shaft 16 with respect to the axis P1 of the control cam 17 is changed.

  The control shaft 16 is configured to be rotationally driven by a DC servo motor (actuator) 121 within a predetermined rotational angle range limited by a stopper with the configuration shown in FIG. Is changed by the actuator 121 so that the valve lift amount and the valve operating angle of the intake valve 105 continuously change within a variable range between the maximum valve lift amount and the minimum valve lift amount limited by the stopper. (See FIG. 9).

In FIG. 10, the DC servo motor 121 is arranged so that its rotation shaft is parallel to the control shaft 16, and a bevel gear 122 is pivotally supported at the tip of the rotation shaft.
On the other hand, a pair of stays 123a and 123b are fixed to the tip of the control shaft 16, and a nut 124 is swingably supported around an axis parallel to the control shaft 16 connecting the tips of the pair of stays 123a and 123b. The

A bevel gear 126 meshed with the bevel gear 122 is pivotally supported at the tip of the screw rod 125 meshed with the nut 124, and the screw rod 125 is rotated by the rotation of the DC servo motor 121. The position of the nut 124 that meshes with the 125 is displaced in the axial direction of the screw rod 125 so that the control shaft 16 is rotated.
Here, the direction in which the position of the nut 124 is brought closer to the bevel gear 126 is a direction in which the valve lift amount is reduced, and conversely, the direction in which the position of the nut 124 is moved away from the bevel gear 126 is a direction in which the valve lift amount is increased. ing.

As shown in FIG. 10, a potentiometer type angle sensor 127 for detecting the angle of the control shaft 16 is provided at the tip of the control shaft 16, and the actual angle detected by the angle sensor 127 is the target angle. The ECU 114 feedback-controls the DC servo motor 121 so as to match (a target valve lift amount equivalent value).
In addition, the stopper member 128 protruding from the outer periphery of the control shaft 16 abuts on a receiving member (not shown) on the fixed side in both the increasing direction and decreasing direction of the valve lift, thereby rotating the control shaft 16. The range is regulated so that the minimum valve lift amount and the maximum valve lift amount are defined.

Next, the configuration of the VTC mechanism 113 will be described with reference to FIG.
The VTC mechanism 113 in the present embodiment is a vane type variable valve timing mechanism, and is connected to a cam sprocket 51 (timing sprocket) rotated by a crankshaft 120 via a timing chain and an end portion of the intake camshaft 13. A rotating member 53 that is fixed and rotatably accommodated in the cam sprocket 51, a hydraulic circuit 54 that rotates the rotating member 53 relative to the cam sprocket 51, and a relative relationship between the cam sprocket 51 and the rotating member 53. And a lock mechanism 60 that selectively locks the rotational position at a predetermined position.

The cam sprocket 51 includes a rotating part (not shown) having a tooth part meshed with a timing chain (or timing belt) on the outer periphery, and a housing that is disposed in front of the rotating part and rotatably accommodates the rotating member 53. 56, and a front cover and a rear cover (not shown) for closing the front and rear openings of the housing 56.
The housing 56 has a cylindrical shape with openings at the front and rear ends, and has a trapezoidal shape in cross section on the inner peripheral surface, and four partition walls 63 provided along the axial direction of the housing 56 are spaced by 90 °. It is projecting at.

The rotating member 53 is fixed to the front end portion of the intake side camshaft 14, and four vanes 78 a, 78 b, 78 c, 78 d are provided on the outer peripheral surface of the annular base 77 at 90 ° intervals.
Each of the first to fourth vanes 78a to 78d has a substantially inverted trapezoidal cross section, and is disposed in a recess between the partition walls 63. The recesses are separated from each other in the rotational direction, and the vanes 78a to 78d. An advance side hydraulic chamber 82 and a retard side hydraulic chamber 83 are formed between both sides and both side surfaces of each partition wall 63.

The lock mechanism 60 is configured such that the lock pin 84 engages with an engagement hole (not shown) at the rotation position (reference operation state) on the maximum retard angle side of the rotation member 53.
The hydraulic circuit 54 includes two systems, a first hydraulic passage 91 that supplies and discharges hydraulic pressure to the advance side hydraulic chamber 82 and a second hydraulic passage 92 that supplies and discharges hydraulic pressure to the retard side hydraulic chamber 83. These hydraulic passages 91 and 92 are connected to a supply passage 93 and drain passages 94a and 94b through passage switching electromagnetic switching valves 95, respectively.

The supply passage 93 is provided with an engine-driven oil pump 97 that pumps oil in the oil pan 96, while the downstream ends of the drain passages 94 a and 94 b communicate with the oil pan 96.
The first hydraulic passage 91 is connected to four branch passages 91 d that are formed substantially radially in the base 77 of the rotating member 53 and communicate with the advance-side hydraulic chambers 82. It is connected to four oil holes 92 d that open to the retard side hydraulic chamber 83.

The electromagnetic switching valve 95 is configured such that an internal spool valve body relatively switches and controls the hydraulic passages 91 and 92, the supply passage 93, and the drain passages 94a and 94b.
The ECU 114 controls the energization amount for the electromagnetic actuator 99 that drives the electromagnetic switching valve 95 based on a duty control signal on which a dither signal is superimposed.
For example, when a control signal (OFF signal) with a duty ratio of 0% is output to the electromagnetic actuator 99, the hydraulic oil pressure-fed from the oil pump 47 is supplied to the retard-side hydraulic chamber 83 through the second hydraulic passage 92. At the same time, the hydraulic oil in the advance side hydraulic chamber 82 is discharged from the first drain passage 94 a into the oil pan 96 through the first hydraulic passage 91.

Therefore, the internal pressure of the retard side hydraulic chamber 83 is high and the internal pressure of the advance side hydraulic chamber 82 is low, and the rotating member 53 rotates to the maximum retard side via the vanes 78a to 78b. The opening period (opening timing and closing timing) of the intake valve 105 is delayed.
On the other hand, when a control signal (ON signal) with a duty ratio of 100% is output to the electromagnetic actuator 99, the hydraulic oil is supplied into the advance side hydraulic chamber 82 through the first hydraulic passage 91 and the retard side hydraulic pressure is supplied. The hydraulic oil in the chamber 83 is discharged to the oil pan 96 through the second hydraulic passage 92 and the second drain passage 94b, and the retard side hydraulic chamber 83 becomes low pressure.

For this reason, the rotating member 53 rotates to the maximum advance side via the vanes 78a to 78d, and thereby the opening period (opening timing and closing timing) of the intake valve 105 is advanced.
Note that a variable valve timing mechanism that makes the valve lift amount of the intake valve 105 variable, and a variable valve timing mechanism that makes the center phase of the operating angle of the intake valve 105 variable by changing the rotational phase of the camshaft with respect to the crankshaft. It is obvious that the above is not limited to the VEL mechanism 112 and the VTC mechanism 113 configured as described above.

As described above, the ECU 114 controls the VEL mechanism 112 and the VTC mechanism 113 so that the required intake air amount, the required cylinder residual gas rate, and the like can be obtained, and the valve timing, operating angle, and valve lift amount of the intake valve 105 are controlled. adjust.
Here, by measuring the phase difference between the crank angle signal output from the crank angle sensor 117 and the cam signal output from the cam sensor 132, the center phase of the operating angle of the intake valve is detected, and based on the detection result. The VEL mechanism 112 and the VTC mechanism 113 are controlled.

Since the detection of the center phase using the crank angle sensor 117 and the cam sensor 132 is performed every time a detection signal is output from the sensor, that is, every certain crank angle, the center phase is detected during the detection cycle. In the phase transient state, a deviation occurs between the actual center phase and the detection result.
Therefore, when the operating angle of the intake valve 105 is adjusted by controlling the VEL mechanism 112 based on the center phase in the detection result of the sensor, the opening timing and closing timing of the intake valve 105 transiently exceed the limit, There is a possibility that it will be delayed and it will not be possible to meet the demand for residual cylinder gas and effective displacement.

Therefore, in the present embodiment, the operating angle limiter of the intake valve 105 is set by the routine shown in the flowcharts of FIGS. 12 and 13, and the operating angle target of the intake valve 105 is limited by the routine shown in the flowchart of FIG. As a configuration.
In the routines shown in the flowcharts of FIGS. 12 and 13, first, in step S1, a change in the center phase during the center phase detection period using the crank angle sensor 117 and the cam sensor 132 is estimated.

In the estimation, a transfer function that mathematically expresses a relationship between a duty control signal (operation signal) for the electromagnetic actuator 99 of the VTC mechanism 113 and an actual center phase is set in advance, and duty control at that time is based on the transfer function. The center phase is obtained from the signal, and the rotational phase during the detection period is estimated from the change in the center phase obtained based on the transfer function.
In addition, a rotational phase sensor whose output changes in conjunction with a change in rotational phase between the crankshaft and the camshaft is provided, and the rotational phase from the time point when the rotational phase is detected using the crank angle sensor 117 and the cam sensor 132 is provided. The amount of change may be obtained based on the detection result of the rotational phase sensor, and the rotational phase during the detection period using the crank angle sensor 117 and the cam sensor 132 may be estimated.

  Even if there is a variation in the absolute value of the rotational phase detected by the rotational phase sensor, the amount of change in the rotational phase can be obtained with relatively high accuracy, so that it was detected using the crank angle sensor 117 and the cam sensor 132. If the rotational phase sensor is used to detect subsequent changes with the rotational phase as a reference, the rotational phase during the detection cycle using the crank angle sensor 117 and the cam sensor 132 can be accurately estimated.

Further, sensors capable of detecting the angular positions of the crankshaft and the camshaft at respective arbitrary timings are provided. Based on the comparison of the angular positions of the crankshaft and the camshaft detected by these sensors, the crank angle sensor 117, the cam sensor It is also possible to estimate the rotational phase during the detection period using 132.
In step S2, the center phase detected using the crank angle sensor 117 and the cam sensor 132 is compared with the estimated value obtained in step S1.

In step S3, it is determined whether or not the estimated value obtained in step S1 is advanced with respect to the center phase detected using the crank angle sensor 117 and the cam sensor 132.
If the estimated value is advanced, the process proceeds to step S4.
In step S4, the opening timing IVO (estimated IVO) of the intake valve 105 when the VEL mechanism 112 is controlled to the target (target operating angle) in a state where the center phase is an estimated value is determined from the cylinder residual gas request amount. It is determined whether or not it is an advance side with respect to an advance angle limit (IVO limiter) of the open timing IVO.

When the estimated IVO is on the more advanced side than the IVO limiter, the process proceeds to step S5, and in the state where the center phase is the estimated value, the operating angle for setting the opening timing IVO of the intake valve 105 to the IVO limiter position is Calculate based on the formula.
Operating angle = (center phase at the most retarded angle−estimated advance amount−IVO limiter) × 2
The above-mentioned “center phase at the most retarded angle” is the center phase of the operating angle of the intake valve 105 when the VTC mechanism 113 is controlled to the most retarded angle side, and in this embodiment, as the crank angle from the compression TDC. For example, 470 ° CA.

The “estimated advance amount” is an advance amount of the estimated value with respect to the “center phase at the most retarded angle”, and is represented by a crank angle.
Therefore, “the center phase at the most retarded angle−the amount of advance of the estimation” indicates the crank angle from the compression TDC of the estimated value of the center phase.
Further, the “IVO limiter” is an advance angle limit of the opening timing IVO determined from the residual gas requirement, and is indicated as a crank angle from the compression TDC.

Therefore, “center phase at the most retarded angle−estimated advance amount−IVO limiter” corresponds to half the operating angle for setting the opening timing IVO of the intake valve 105 to the IVO limiter at the estimated center phase, By doubling this, the maximum operating angle is obtained.
Here, if the control target of the VEL mechanism 112 is limited so as to be within the operating angle obtained in step S5, the intake valve 105 may be used even if the actual center phase is the above-mentioned estimated value on the more advanced side. It is avoided that the opening timing IVO is advanced beyond the advance angle limit.

On the other hand, when it is determined in step S4 that the estimated IVO is not on the advance side of the IVO limiter, the process proceeds to step S6.
In step S6, the closing timing IVC (detection IVC) of the intake valve 105 when the VEL mechanism 112 is controlled to the target (target operating angle) in the state of the center phase detected using the crank angle sensor 117 and the cam sensor 132 is It is determined whether or not it is behind the delay angle limit (IVC limiter) of the closing timing IVC determined from the request for the effective exhaust amount.

That is, when the process proceeds to step S6, the center phase detected using the crank angle sensor 117 and the cam sensor 132 is on the retard side with respect to the estimated value, and the actual center phase is set to the crank angle sensor 117 and the cam sensor 132. When the center phase coincides with the detected center phase, the closing timing IVC of the intake valve 105 may be delayed beyond the retard limit.
Therefore, in step S6, it is determined whether or not the closing timing IVC of the intake valve 105 is retarded beyond the retard limit based on the center phase detected using the crank angle sensor 117 and the cam sensor 132, If it is determined that the retard limit is exceeded, the process proceeds to step S7, and the closing timing IVC exceeds the retard limit even in the state of the center phase detected using the crank angle sensor 117 and the cam sensor 132. The maximum operating angle is calculated.

Specifically, the maximum operating angle is calculated by the following equation.
Operating angle = (IVC limiter−center phase at the most retarded angle + advance amount of detection) × 2
Here, the “IVC limiter” is a delay angle limit of the closing timing IVC determined from the request for the effective displacement, and is indicated as a crank angle from the compression TDC.
The “advance amount of detection” is an advance amount of the center phase detected by using the crank angle sensor 117 and the cam sensor 132 with respect to the “center phase at the most retarded angle”, and is indicated by the crank angle.

  The “IVC limiter—center phase at the most retarded angle” corresponds to half of the operating angle for setting the closing timing IVC of the intake valve 105 to the IVC limiter when the center phase is most retarded. By adding the “advancing amount of detection”, in the state of the center phase detected using the crank angle sensor 117 and the cam sensor 132, half the operating angle for setting the closing timing IVC of the intake valve 105 as an IVC limiter. Is obtained, and the maximum operating angle is obtained by doubling this value.

In step S8, referring to a pre-stored table showing the correlation between the angle of the control shaft 16 and the operating angle, the maximum operating angle obtained in step S5 or step S7 is set as the limit value of the target angle of the control shaft 16. Convert to
When it is determined in step S3 that the estimated value of the center phase is not advanced, that is, the center phase detected using the crank angle sensor 117 and the cam sensor 132 is the same as the estimated value. If the angle is on the more advanced side, the process proceeds to step S9.

In step S9, the opening timing IVO (detection IVO) of the intake valve 105 when the VEL mechanism 112 is controlled to the target (target operating angle) in the state of the center phase detected using the crank angle sensor 117 and the cam sensor 132 is It is determined whether or not it is an advance side with respect to the advance limit (IVO limiter) of the opening timing IVO determined from the required cylinder residual gas amount.
If it is determined in step S9 that the detected IVO is on the more advanced side than the IVO limiter, the process proceeds to step S10, and the maximum operating angle is obtained by the following equation.

Operating angle = (center phase at the most retarded angle−advance amount of detection−IVO limiter) × 2
When the process proceeds to step S9, since the center phase detected using the crank angle sensor 117 and the cam sensor 132 is further advanced, the "estimated advance angle" used in the calculation of the maximum operating angle in step S5. The maximum operating angle is calculated using “the advance amount of detection” instead of “amount”.

On the other hand, if it is determined in step S9 that the detected IVO is not on the advance side of the IVO limiter, the closing timing IVC of the intake valve 105 reaches the retard limit when the estimated center phase is on the more retarded side. It is determined that there is a possibility of exceeding, and the process proceeds to step S11.
In step S11, the closing timing IVC (estimated IVC) of the intake valve 105 when the VEL mechanism 112 is controlled to the target (target operating angle) in a state where the center phase is the estimated value is determined from the request for the effective exhaust amount. It is determined whether or not it is on the retard side with respect to the retard limit (IVC limiter) of the closing timing IVC.

When the estimated IVC is on the retard side with respect to the IVC limiter, the process proceeds to step S12, and the maximum operating angle is obtained by the following equation.
Operating angle = (IVC limiter−center phase at the most retarded angle + estimated advance amount) × 2
When the process proceeds to step S12, the estimated value of the center phase is more retarded, so that “estimated advance angle” is used instead of the “advance amount of detection” used in the calculation of the maximum operating angle in step S7. The maximum operating angle is calculated using the “quantity”.

In step S13, as in step S8, the maximum operating angle obtained in step S10 or step S12 is converted into a target angle limit value of the control shaft 16.
The flowchart in FIG. 14 shows processing for limiting the control target of the VEL mechanism 112 based on the limit value of the target angle set in step S8 or step S13.
In the flowchart of FIG. 14, in step S21, it is determined whether or not the target angle of the control shaft 16 calculated based on the required intake air amount exceeds the limit value, in other words, the target operating angle is the maximum operating angle. It is discriminated whether or not it is larger.

When it is determined that the target angle of the control shaft 16 exceeds the limit value, the process proceeds to step S22, and the limit value is set as the final target angle of the control shaft 16.
Thus, even during the center phase detection cycle using the crank angle sensor 117 and the cam sensor 132, the opening timing IVO of the intake valve 105 exceeds the advance limit, and the closing timing IVC exceeds the retard limit. Can be avoided.

On the other hand, when the target angle of the control shaft 16 does not exceed the limit value, the process proceeds to step S23, and the target angle of the control shaft 16 calculated based on the required intake air amount or the like is set as the final target value as it is. To do.
In step S24, the DC servo motor 121 is feedback-controlled so that the angle of the control shaft 16 matches the final target value set in steps S22 and S23.

In the above-described embodiment, the VEL mechanism 112 and the VTC mechanism 113 are provided on the intake valve 105 side. However, in the configuration provided with the VEL mechanism 112 and the VTC mechanism 113 on the exhaust valve 107 side, The operating angle of the exhaust valve 107 can be limited so that the opening timing does not exceed the retard limit / advance limit.
Here, technical ideas other than the claims that can be grasped from the above embodiment will be described together with the effects thereof.
(A) In the variable valve control apparatus for an internal combustion engine according to claim 2 or 3,
The engine valve is an intake valve, and the advance timing limit of the opening timing is set based on a request for the cylinder residual gas amount, and the retardation limit of the closing timing is set based on a request for an effective exhaust amount. A variable valve control apparatus for an internal combustion engine.

According to such a configuration, the cylinder residual gas amount is required because the opening timing of the intake valve exceeds the advance angle limit while the center phase is detected at every constant crank angle based on the detection result of the reference rotational position. It can be avoided that the amount exceeds the limit, and the effective exhaust amount is prevented from becoming smaller than required due to the closing timing of the intake valve exceeding the retard limit.
(B) In the variable valve control apparatus for an internal combustion engine according to any one of claims 1 to 3,
Equipped with a rotational phase sensor whose output changes in conjunction with the change in rotational phase of the crankshaft and camshaft,
A variable valve for an internal combustion engine, wherein a change from a center phase detected based on a detection signal of a reference rotational position of the crankshaft and camshaft is estimated based on a detection result of the rotational phase sensor. Control device.

According to this configuration, since the change in the rotation phase during the center phase detection period based on the detection signal of the reference rotation position is estimated from the change in the rotation phase detected by the rotation phase sensor, the rotation during the detection period is performed. The phase can be estimated with high accuracy.
(C) In the variable valve control apparatus for an internal combustion engine according to any one of claims 1 to 3,
A variable valve control apparatus for an internal combustion engine, wherein a change in the center phase is estimated based on an operation signal of the variable valve timing mechanism and a predetermined transfer function.

According to such a configuration, the characteristic of the actual center phase that gradually changes with a predetermined delay after the operation signal is output to the variable valve timing mechanism is approximated by a transfer function, and the center phase is detected based on the reference rotation position detection signal. The change of the center phase is estimated while.

1 is a system configuration diagram of an internal combustion engine in an embodiment. Sectional drawing (AA sectional drawing of FIG. 3) which shows a VEL (Variable valve Event and Lift) mechanism. The side view of the said VEL mechanism. The top view of the said VEL mechanism. The perspective view which shows the eccentric cam used for the said VEL mechanism. Sectional drawing which shows the effect | action at the time of the low lift of the said VEL mechanism (BB sectional drawing of FIG. 3). Sectional drawing which shows the effect | action at the time of the high lift of the said VEL mechanism (BB sectional drawing of FIG. 3). The valve lift characteristic view corresponding to the base end surface and cam surface of the swing cam in the VEL mechanism. FIG. 6 is a characteristic diagram of valve timing and valve lift of the VEL mechanism. The perspective view which shows the rotational drive mechanism of the control shaft in the said VEL mechanism. The longitudinal cross-sectional view which shows a VTC (Variable valve Timing Control) mechanism. The flowchart which shows the routine which sets the target limit value of a VEL mechanism. The flowchart which shows the routine which sets the target limit value of a VEL mechanism. The flowchart which shows the limit process of the target value of a VEL mechanism.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 13 ... Camshaft, 16 ... Control shaft, 101 ... Internal combustion engine, 104 ... Electronically controlled throttle, 105 ... Intake valve, 112 ... VEL mechanism (variable valve mechanism), 113 ... VTC mechanism (variable valve timing mechanism), 114 ... Engine control unit (ECU), 117 ... crank angle sensor, 120 ... crankshaft, 121 ... DC servo motor, 127 ... angle sensor, 132 ... cam sensor

Claims (3)

An internal combustion engine provided with a variable valve timing mechanism that varies the center phase of the engine valve operating angle by changing the rotational phase of the camshaft relative to the crankshaft, and a variable valve mechanism that varies the engine valve operating angle In the variable valve control device of
Detecting the center phase based on a detection signal of a reference rotational position of the crankshaft and the camshaft, and estimating a change in the center phase during a detection period of the center phase based on the detection signal ;
Based on the center phase detected based on the detection signal of the reference rotational position and the estimated value of the center phase, the maximum value of the operating angle of the engine valve is set, and the target of the operating angle in the variable valve mechanism is set. A variable valve control apparatus for an internal combustion engine, characterized by being limited to the maximum value or less . The limit value of the operating angle corresponding to the engine valve operating range, regardless of whether the opening / closing timing of the engine valve is selected as a control parameter between the center phase detected based on the detection signal of the reference rotational position and the estimated value. 2. The variable valve control apparatus for an internal combustion engine according to claim 1 , wherein the maximum value of the operating angle is set so as to be within . Relative to the direction which is more advanced between the estimated value and the detected center phase based on the detection signal of the reference rotational position, as opening timing of the engine valve does not exceed the advance-angle limit, operation of the engine valve While setting the maximum value of the corner ,
The operation of the engine valve is performed so that the closing timing of the engine valve does not exceed the retard limit on the basis of the delayed one of the center phase detected based on the detection signal of the reference rotational position and the estimated value. 2. The variable valve control apparatus for an internal combustion engine according to claim 1 , wherein a maximum value of the angle is set .

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