JP2010024877A - Variable valve control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid a controlled variable from transiently exceeding a limit value for an internal combustion engine which has a variable valve train for continuously varying the opening property of an engine valve. <P>SOLUTION: The engine has a center phase varying mechanism for continuously varying the center phase of the valve operating angle of an intake valve, and an operating angle varying mechanism for continuously varying the valve operating angle of the intake valve. Herein, a change in an opening timing IVO of the intake valve is predicted in accordance with the operation amount and transfer function of each varying mechanism. When the predicted opening timing IVO exceeds an advance timing limit, a change in the control target of the side out of the varying mechanisms, having a smaller response time constant, is restricted to be smaller. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a variable valve control device for an internal combustion engine provided with a variable valve mechanism that continuously varies an opening characteristic of an engine valve.

  Patent Document 1 discloses a lift / operating angle variable mechanism that continuously changes a valve operating angle and a valve lift amount of an intake valve, and a center phase variable mechanism that continuously changes a central phase of the valve operating angle of the intake valve. When the valve lift amount, the valve operating angle, and the change amount of the center phase exceed predetermined threshold values, respectively, one of the lift / operating angle variable mechanism and the center phase variable mechanism is After driving, the other is driven.

According to the drive control described above, it is possible to prevent the opening characteristic from becoming unauthorized during the switching of the opening characteristic of the intake valve.
JP 2001-280167 A

  By the way, for example, the central phase of the valve operating angle of the intake valve is delayed and the opening timing of the intake valve is changed almost in parallel with increasing the valve lift amount and the valve operating angle of the intake valve. Without increasing the valve lift amount and the valve operating angle, if the time required to increase the valve lift amount to the required value is shorter than the time required to delay the center phase by the required angle, As a result, the valve lift amount increases ahead of the delay change in the center phase. As a result, the opening timing of the intake valve changes once in the advance direction, then changes in delay, and converges to the final target. .

Therefore, when the valve lift amount and valve operating angle of the intake valve and the center phase are changed at the same time, an excessive advance angle of the opening timing is temporarily generated, which results in excessive valve overlap and residual gas. And combustion stability may be impaired.
On the other hand, if the valve lift amount and the valve operating angle are increased after the center phase is changed by a retarded angle, the opening timing of the intake valve can be prevented from being greatly advanced. it can.

However, as described above, if the retardation control of the center phase is executed first and the increase control of the valve lift amount is performed later, the change in the valve lift amount (intake air amount) increases with respect to the acceleration request. Will be delayed and the acceleration response will be worsened.
The present invention has been made in view of the above problems, and is capable of avoiding that the controlled variable exceeds the limit value transiently without excessively delaying the change in the opening characteristics of the engine valve. An object is to provide a control device.

  Therefore, the variable valve control apparatus for an internal combustion engine according to the present invention predicts a change in the control amount of the variable valve mechanism based on an operation amount of the variable valve mechanism that continuously varies the opening characteristics of the engine valve. When the predicted control amount exceeds the limit value, the operation of the variable valve mechanism is limited so that the control amount does not exceed the limit value.

According to the above invention, based on the operation amount of the variable valve mechanism, a change in a transient control amount (for example, valve timing) is predicted, and if the predicted control amount exceeds the limit value, the operation of the variable valve mechanism By limiting the control amount, the control amount is prevented from exceeding the limit value.
For example, when the delay control of the center phase of the engine valve and the increase control of the valve lift amount of the engine valve are performed simultaneously, the increase change of the valve lift amount precedes the change of the delay angle of the center phase. When the valve timing (for example, the opening timing of the intake valve) is transiently over-advanced, the over-advance angle of the valve timing is predicted from the manipulated variable, and the variable valve mechanism is previously Limit operation.

  Therefore, it is possible to suppress or prevent the controlled variable from transiently exceeding the limit value, and it is possible to suppress or prevent deterioration in combustibility during transient operation that changes the opening characteristics of the engine valve.

Embodiments of the present invention will be described below.
FIG. 1 is a system configuration diagram of an internal combustion engine for a vehicle according to an embodiment.
In FIG. 1, an intake pipe 102 of an internal combustion engine (gasoline engine) 101 is provided with an electronically controlled throttle 104 that opens and closes a throttle valve 103b by a throttle motor 103a, and the electronically controlled throttle 104 and the intake valve 105 are interposed therebetween. Then, air is sucked into the combustion chamber 106.

In addition, 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 has an injection pulse width of an injection pulse signal sent from the engine control unit 114. Inject a proportional amount of fuel (gasoline).
The fuel sucked into the combustion chamber 106 together with air is ignited and burned by spark ignition by a spark plug (not shown).

Note that it may be a direct injection type internal combustion engine in which fuel is directly injected into the combustion chamber.
The combustion exhaust in the combustion chamber 106 is discharged from the combustion chamber 106 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 exhaust valve 107 is driven to open and close by a cam 111 pivotally supported on the exhaust camshaft 110. By changing the rotational phase of the exhaust camshaft 110 with respect to the crankshaft 120, the valve operating angle of the exhaust valve 107 can be adjusted. A center phase variable mechanism 113b that continuously changes the center phase is provided.

That is, although the exhaust valve 107 is driven to open and close while maintaining a constant valve lift amount and valve operating angle, the central phase of the valve operating angle is continuously changed by the central phase varying mechanism 113b. Then, the opening timing EVO and the closing timing EVC of the exhaust valve 107 change.
On the other hand, in the intake valve 105, the rotational phase of the intake camshaft 3 with respect to the crankshaft 120 is changed by a central phase variable mechanism 113a which is the same mechanism as that provided on the exhaust side, so that the central phase of the valve operating angle is changed. Is continuously variably controlled, and the lift / operating angle variable mechanism 112 continuously variably controls the valve lift amount and the valve operating angle.

The center phase variable mechanisms 113a and 113b and the lift / operating angle variable mechanism 112 correspond to a variable valve mechanism that continuously varies the opening characteristics of the engine valve in this embodiment.
The engine control unit 114 incorporating the microcomputer sets the fuel injection amount, ignition timing, target torque, target manifold pressure, and the like by arithmetic processing according to a program stored in advance, and the fuel injection valve 131 based on these. , The operation amount (control signal) is output to the power transistor for the ignition coil, the electronic control throttle 104, the lift / operating angle variable mechanism 112, and the center phase variable mechanisms 113a and 113b.

  The engine control unit 114 includes an air flow sensor 115 for detecting the intake air flow rate QA of the internal combustion engine 101, an accelerator pedal sensor 116 for detecting an accelerator pedal depression amount (accelerator opening) ACC operated by a vehicle driver, A crank angle sensor 117 that outputs a crank angle signal CAS for each reference rotational position of the shaft 120, a throttle sensor 118 that detects the opening TVO of the throttle valve 103b, a water temperature sensor 119 that detects the cooling water temperature TW of the internal combustion engine 101, and intake air Detection signals from an intake cam sensor 132 that outputs a cam signal CAMIN for each reference rotational position of the camshaft 3 and an exhaust cam sensor 133 that outputs a cam signal CAMEX for each reference rotational position of the exhaust camshaft 110 are input.

FIG. 2 is a perspective view showing the structure of the lift / operating angle variable mechanism 112 that continuously varies the valve lift amount and valve operating angle of the intake valve 105.
An intake camshaft 3 that is rotationally driven by the crankshaft 120 is supported above the intake valve 105 so as to be rotatable along the cylinder row direction.
A swing cam 4 that contacts the valve lifter 105a of the intake valve 105 and opens and closes the intake valve 105 is fitted on the intake camshaft 3 so as to be relatively rotatable.

Between the intake camshaft 3 and the swing cam 4, there is provided a variable lift / operating angle mechanism 112 for continuously changing the valve operating angle and valve lift amount of the intake valve 105.
Further, at one end of the intake camshaft 3, a center phase variable for continuously changing the center phase of the valve operating angle of the intake valve 105 by changing the rotational phase of the intake camshaft 3 with respect to the crankshaft 120. A mechanism 113a is provided.

  As shown in FIGS. 2 and 3, the lift / operating angle variable mechanism 112 includes a circular drive cam 11 that is eccentrically fixed to the intake camshaft 3, and is externally fitted to the drive cam 11 so as to be relatively rotatable. A ring-shaped link 12 that extends, a control shaft 13 that extends substantially parallel to the intake camshaft 3 in the cylinder row direction, a circular control cam 14 that is fixed to the control shaft 13 in an eccentric manner, and the control cam 14 A rocker arm 15 that is fitted so as to be relatively rotatable and has one end connected to the tip of the ring-shaped link 12, and a rod-shaped link 16 connected to the other end of the rocker arm 15 and the swing cam 4. ing.

The control shaft 13 is rotationally driven within a predetermined control range via a gear train 18 by an actuator such as a motor 17.
With the above configuration, when the intake camshaft 3 rotates in conjunction with the crankshaft 120, the ring-shaped link 12 moves substantially in translation through the drive cam 11, and the rocker arm 15 swings around the axis of the control cam 14. Then, the swing cam 4 swings through the rod-shaped link 16 and the intake valve 105 is driven to open and close.

Further, by driving and controlling the motor 17 to change the rotation angle of the control shaft 13, the axial center position of the control cam 14 serving as the rocking center of the rocker arm 15 changes and the posture of the rocking cam 4 changes. .
As a result, the valve operating angle and the valve lift amount of the intake valve 105 continuously change while the central phase of the valve operating angle of the intake valve 105 remains substantially constant.

The variable lift / operating angle mechanism 112 may be configured so that the central phase of the valve operating angle changes simultaneously with the continuous change of the valve operating angle and the valve lift amount.
A detection signal from an angle sensor 134 that detects the rotation angle of the control shaft 13 is input to the engine control unit 114, and the control shaft 13 is rotated to a target angle position corresponding to a target lift amount. Based on the detection result of the angle sensor 134, the energization control duty of the motor 17 is feedback-controlled.

A hydraulic actuator can be used in place of the motor 17 as an actuator for rotating the control shaft 13.
FIG. 4 shows the structure of the center phase variable mechanism 113a that makes the center phase of the valve operating angle of the intake valve 105 variable.
The center phase variable mechanism 113a is fixed to the cam sprocket 51 (timing sprocket) rotated by a crankshaft 120 via a timing chain and the end of the intake camshaft 3, and is rotatable in the cam sprocket 51. The rotary member 53 accommodated, the hydraulic circuit 54 for rotating the rotary member 53 relative to the cam sprocket 51, and the relative rotational position of the cam sprocket 51 and the rotary member 53 are selectively locked at predetermined positions. And a lock mechanism 60.

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 camshaft 3, 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 initial position of the rotating 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 engine control unit 114 controls the energization amount for the electromagnetic actuator 99 that drives the electromagnetic switching valve 95 based on a duty control signal (operation amount) on which a dither signal is superimposed.

  In the center phase variable mechanism 113 a, when a control signal (OFF signal) having a duty ratio (ON time ratio) of 0% is output to the electromagnetic actuator 99, the hydraulic oil pumped from the oil pump 47 passes through the second hydraulic passage 92. The hydraulic oil in the advance side hydraulic chamber 82 is discharged to the oil pan 96 from the first drain passage 94a through the first hydraulic passage 91. is there.

  Therefore, in the center phase variable mechanism 113a, when a control signal (OFF signal) with a duty ratio of 0% is output to the electromagnetic actuator 99, the internal pressure of the retard side hydraulic chamber 83 increases while the advance side hydraulic chamber 82 The internal pressure decreases, and the rotating member 53 rotates to the maximum retard angle side via the vanes 78a to 78b. As a result, the opening period of the intake valve 105 (the central phase of the valve operating angle) is relative to the piston position. The angle changes slowly.

That is, when the energization of the electromagnetic actuator 99 of the center phase variable mechanism 113a is cut off, the center phase of the valve operating angle of the intake valve 105 changes with a delay, and finally stops at the most retarded position.
When the center phase variable mechanism 113 a outputs a control signal (ON signal) with a duty ratio of 100% to the electromagnetic actuator 99, the hydraulic oil is supplied into the advance hydraulic chamber 82 through the first hydraulic passage 91. At the same time, the hydraulic oil in the retard side hydraulic 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, when the control signal (ON signal) with a duty ratio of 100% is output in the center phase variable mechanism 113a, the rotating member 53 rotates to the maximum advance side via the vanes 78a to 78d. The opening period of the valve 105 (the center phase of the valve operating angle) changes relative to the piston position.
The exhaust-side central phase varying mechanism 113b has basically the same structure as the intake-side central phase varying mechanism 113a. However, when the electromagnetic actuator 99 is turned off, the internal pressure of the retard-side hydraulic chamber 83 is low. The internal pressure of the advance side hydraulic chamber 82 is configured to be high.

  That is, in the center phase variable mechanism 113b, when a control signal (OFF signal) with a duty ratio of 0% is output, the internal pressure of the retard side hydraulic chamber 83 decreases while the internal pressure of the advance side hydraulic chamber 82 increases. The rotation member 53 rotates to the maximum advance angle side via the vanes 78a to 78b. As a result, the open period of the exhaust valve 107 (the central phase of the valve operating angle) changes relative to the piston position. To do.

That is, when the energization of the electromagnetic actuator 99 of the center phase variable mechanism 113b is cut off, the center phase of the valve operating angle of the exhaust valve 107 is advanced and finally stops at the most advanced position.
On the other hand, when the control signal (ON signal) with a duty ratio of 100% is output from the center phase variable mechanism 113b, the opening period of the exhaust valve 107 (the center phase of the valve operating angle) changes relative to the piston position. To do.

Therefore, the initial position of the intake-side center phase varying mechanism 113a (default position when the electromagnetic actuator 99 is turned off) is the most retarded position, and the initial position of the exhaust-side center phase varying mechanism 113b is the most advanced position. When the center phase variable mechanisms 113a and 113b are both at the initial positions, the valve overlap is set to be minimum.
The lift / operating angle variable mechanism 112 for continuously changing the operating angle / lift amount of the intake valve 105, and the center for continuously changing the central phase of the valve operating angles of the intake valve 105 / exhaust valve 107. The phase variable mechanisms 113a and 113b are not limited to those shown in FIGS.

  For example, as a center phase variable mechanism that continuously varies the center phase of the valve operating angle, the intake camshaft 3 and the exhaust camshaft 110 are made relative to the crankshaft 120 using a gear in addition to the vane type described above. A rotating mechanism or the like can be used, and a mechanism using a motor or an electromagnetic brake as an actuator can be employed in addition to a hydraulic actuator.

Further, for example, the above vane mechanism is employed as the intake-side center phase varying mechanism 113a, while the electromagnetic brake mechanism is employed as the exhaust-side center phase varying mechanism 113b. The center phase variable mechanism having a different mechanism can be used.
The engine control unit 114 calculates the target rotation angle of the control shaft 13 corresponding to the target values of the valve operating angle and valve lift amount of the intake valve 105 based on the engine operating conditions, and is detected by the angle sensor 134. The on-duty (operation amount) of the motor 17 is feedback-controlled so that the actual rotation angle (control amount) of the control shaft 13 approaches the target rotation angle.

  Further, the engine control unit 114 sets the target value (the target advance angle amount on the intake side and the target retard amount on the exhaust side) of the center phase of the valve operating angle based on the engine operating conditions, and the intake valve 105 and the exhaust valve. 107 is calculated for each of the center phases so that the actual center phases (control amounts) of the intake valve 105 and the exhaust valve 107 detected by the crank angle sensor 117 and the cam sensors 132 and 133 approach the target value. The duty ratio (operation amount) of the control signal output to each electromagnetic actuator 99 of the variable mechanisms 113a and 113b is feedback controlled.

As described above, in the intake-side center phase varying mechanism 113a, the electromagnetic actuator 99 is turned off to return to the most retarded position, which is the initial position (default position), and the exhaust-side center phase varying mechanism 113b. In FIG. 2, the electromagnetic actuator 99 is turned off to return to the most advanced position, which is the initial position (default position).
Therefore, for the center phase variable mechanism 113a on the intake side, the target of the center phase is set as the advance amount (advance angle) from the most retarded position, and for the center phase variable mechanism 113b on the exhaust side, the center phase The target is set as a retard amount (retard angle) from the most advanced position.

FIG. 5 shows changes in the opening characteristics of the intake valve 105 by the center phase variable mechanism 113a and the lift / operating angle variable mechanism 112. FIG.
As shown in the figure, when the lift / operating angle variable mechanism 112 is operated, the center phase of the valve operating angle of the intake valve 105 remains substantially constant as indicated by the arrow (A), and the valve of the intake valve 105 is maintained. Both the operating angle and the valve lift amount continuously increase or decrease.

On the other hand, when the center phase variable mechanism 113a is operated, the center phase of the valve operating angle of the intake valve 105 advances while the valve operating angle and the valve lift amount of the intake valve 105 remain constant as shown by arrows (b). The angle changes.
By the way, when the lift / operating angle variable mechanism 112 and the center phase variable mechanisms 113a and 113b are simultaneously driven and controlled to change the opening characteristics of the intake valve 105 and the exhaust valve 107, the time constants of both mechanisms 112 and 113 are used. Due to the difference in (response speed), the opening timing IVO of the intake valve 12 is greatly advanced at the same time, and at the same time, the advance timing of the closing timing EVC of the exhaust valve 107 is delayed, thereby causing the valve overlap to be excessively excessive. The combustion stability may deteriorate.

For example, the example shown in FIG. 6 is a request to advance the valve timing of the exhaust valve 107 when the response time constants of the center phase variable mechanisms 113a and 113b are larger than the response time constant of the lift / operating angle variable mechanism 112. At the same time, a case where a request for delaying the valve timing of the intake valve 105 and increasing the valve lift amount of the intake valve 105 occurs is shown.
Here, if the time constants of the center phase variable mechanisms 113a and 113b are larger than the time constant of the lift / operating angle variable mechanism 112, the valve timing of the intake valve 105 is delayed and the valve timing of the exhaust valve 107 is advanced. On the other hand, the increase in the lift amount of the intake valve 105 is advanced in advance.

As a result, the target of the opening timing IVO of the intake valve 105 is on the retard side with respect to that before the change. The phase is retarded to the original target opening timing IVO by the phase retardation control.
In other words, if the valve operating angle increases and changes by an angle twice as much as the change in retardation of the center phase, the valve lift amount increases while the opening timing IVO of the intake valve 105 remains constant. When the increase change margin of exceeds more than twice the retardation change of the center phase, the opening timing IVO of the intake valve 105 temporarily changes the advance angle.

  In the present embodiment, the lift / operating angle variable mechanism 112 is operated by the motor 17, whereas the center phase variable mechanisms 113a and 113b are operated hydraulically. Therefore, when the center phase variable mechanisms 113a and 113b respond. The constant is larger than the response time constant of the lift / operating angle variable mechanism 112, and after the valve lift amount / valve operating angle has changed to the target, the center phase tends to reach the target with a delay. The larger the value, the longer the delay time.

Further, the closing timing EVC of the exhaust valve 107 is advanced according to the request. However, since the advance control is delayed with respect to the increase in the lift amount of the intake valve 105, the opening timing IVO of the intake valve 105 is the lift amount. When the angle of advance advances from the target after the change with the increase of the angle, the advance angle of the closing timing EVC of the exhaust valve 107 does not advance sufficiently.
Therefore, originally, the valve lift amount of the intake valve 105 is increased and at the same time the target change is made to decrease the valve overlap, but the valve overlap becomes transiently larger than before the change and remains in the cylinder. Gas increases and combustion becomes unstable.

Therefore, in the present embodiment, the engine control unit 114 executes the processing shown in the flowchart of FIG. 7 to suppress or prevent the valve overlap from becoming excessively large.
The routine shown in the flowchart of FIG. 7 is repeatedly executed at regular intervals. First, in step S1, the operation amounts (control duty) of the lift / operation angle variable mechanism 112 and the center phase variable mechanisms 113a and 113b are controlled. ), The change in the central phase / valve operating angle of the valve operating angle of the intake valve 105 and the change in the central phase of the valve operating angle of the exhaust valve 107 are predicted.

  The engine control unit 114 stores in advance a transfer function that mathematically expresses the relationship between the operation amount and the control amount in each of the lift / operation angle variable mechanism 112 and the center phase variable mechanisms 113a and 113b. By inputting an operation amount (control duty) into the transfer function, a control amount is obtained as an output, and a change in the control amount (lift / operating angle and center phase) with respect to the operation amount can be predicted.

That is, the transfer function is a model showing the signal transfer characteristics of the lift / operation angle variable mechanism 112 and the center phase variable mechanisms 113a and 113b. It is possible to simulate whether the operating angle and the center phase change.
The control amount can be the angle of the control shaft 13 or the vane angle, and the valve lift amount / valve operating angle, advance angle amount, and retard angle amount can be the control amounts.

  The transfer function G is represented by, for example, the following equation as a general second-order lag system.

Here, ζ is an attenuation ratio, and ω _n is a natural frequency.
The transfer function (model) is constructed by an identification experiment, and a test signal (test operation amount) is given to the lift / operation angle variable mechanism 112 and the center phase variable mechanisms 113a and 113b. The movement of the operating angle and the center phase is detected, and it is specified from the correlation of the input / output data at this time.

  In the step S1, the control duty ratio (operation amount) at that time is input to the transfer functions corresponding to the lift / operating angle variable mechanism 112 and the center phase variable mechanisms 113a and 113b, and the intake air is determined from the output of the transfer function. Changes in the central phase of the valve operating angle of the valve 105, the valve operating angle of the intake valve 105, and the central phase (control amount) of the valve operating angle of the exhaust valve 107 are predicted.

Note that the control amount predicted based on the transfer function is a value that is a predetermined time after the current time, or a value within the previous prediction section, and at which point the control amount is predicted depends on the duty ratio. Are adjusted based on the calculation / output cycle, the transient response (response time constant) of the lift / operating angle variable mechanism 112 and the center phase variable mechanisms 113a, 113b.
Further, when the feedback control of the lift / operating angle variable mechanism 112 and the center phase variable mechanisms 113a and 113b is stopped, the control amount prediction based on the transfer function is stopped. This is because when the feedback control is stopped, the lift / operating angle variable mechanism 112 and the center phase variable mechanisms 113a and 113b may be controlled by another control system. In this case, the control amount is controlled based on the transfer function. This is because it cannot be predicted correctly.

  When the feedback control of the lift / operating angle variable mechanism 112 and the center phase variable mechanisms 113a and 113b is stopped, the control amount is used to learn the output characteristics of the sensor that detects the actual valve lift amount and the actual valve timing. When set to a predetermined value, or when the coolant temperature (engine temperature) becomes high or low, or the engine rotation speed becomes low, and the temperature and rotation speed range deviates from the variable mechanism drive permission conditions. Or when the center phase variable mechanism 113a, 113b is switched to the cleaning mode.

The cleaning mode is a mode in which a control amount is set in order to eliminate or prevent foreign matter from entering the center phase variable mechanisms 113a and 113b. For example, the duty ratio of a duty signal applied to the electromagnetic actuator 99 is a cleaning mode. The increase / decrease change is repeated in a predetermined pattern.
If a change in the central phase / valve operating angle of the valve operating angle of the intake valve 105 and a change in the central phase of the valve operating angle of the exhaust valve 107 are predicted in step S1, the process proceeds to step S2, and the intake valve corresponding to the prediction result is obtained. A predicted opening timing IVO 105 and an estimated closing timing EVC of the exhaust valve 107 are obtained.

In other words, in steps S1 and S2, the future of the opening timing IVO of the intake valve 105 and the closing timing EVC of the exhaust valve 107 is determined from the operation amounts of the lift / operation angle variable mechanism 112 and the center phase variable mechanisms 113a and 113b. Predict changes (prediction means).
The predicted opening timing IVO of the intake valve 105 is obtained as a crank angle position advanced from the predicted center phase by half of the predicted valve operating angle, and the predicted closing timing EVC of the exhaust valve 107 is the predicted center It is obtained as a crank angle position retarded by half the valve operating angle, which is a fixed value, from the phase.

Specifically, the predicted opening timing IVO of the intake valve 105 includes the predicted advance amount of the center phase by the center phase variable mechanism 113a, the center phase when the center phase variable mechanism 113a is at the most retarded position, and the intake air. Based on the predicted valve operating angle of the valve 105, calculation is performed according to the following equation.
Predicted opening timing IVO = center phase at the most retarded position−predicted advance amount−predicted operating angle / 2
Here, the center phase at the most retarded angle position is shown as a retard angle (> 0) from the top dead center TDC, and the center phase advances from the most retarded angle position by the operation of the center phase variable mechanism 113a. Therefore, “center phase at the most retarded angle position−predicted advance amount” is a retard angle from the top dead center TDC to the predicted center phase.

  Since the position advanced from the predicted center phase by half the operating angle of the intake valve 105 is the opening timing IVO, the predicted operating angle / 2 is calculated from “center phase at the most retarded angle position−predicted advance amount”. When the predicted opening time IVO is a negative angle when the value obtained by subtracting is the predicted opening time IVO indicates that the predicted opening time IVO is before the top dead center TDC, and the predicted opening time IVO is a positive angle Indicates that the predicted opening timing IVO is after top dead center TDC.

Therefore, the larger the value of the predicted opening time IVO, the later the opening time IVO, and the smaller the valve overlap.
Further, the predicted closing timing EVC of the exhaust valve 107 is based on the closing timing EVC when the center phase variable mechanism 113b is at the most advanced angle position and the predicted retardation amount of the center phase by the center phase variable mechanism 113b. Calculated according to the formula.

Predicted closing timing EVC = closing timing EVC at the most advanced angle + predicted retardation amount Here, the closing timing EVC is expressed as an angle from the top dead center, and is indicated as positive after the top dead center and negative before the top dead center. Shall.
Therefore, the predicted closing timing EVC becomes a larger value as the center phase is retarded by the center phase variable mechanism 113b. In other words, the smaller the value of the predicted closing timing EVC, the earlier the closing timing EVC, and the smaller the valve overlap.

In the next step S3, based on the operating state of the internal combustion engine 101, the limit value (allowable maximum advance angle position) LIVO of the intake valve 105 and the limit value (allowable maximum delay angle) of the closing timing EVC of the exhaust valve 107 are determined. Position) LEVC is calculated.
The operating state is, for example, an engine load, an engine speed, an engine temperature (cooling water temperature), and the engine load includes a throttle opening, a cylinder intake air amount, a basic fuel injection amount (basic fuel injection pulse width). It can be represented by intake negative pressure.

The limit values LIVO and LEVC indicate the advance / retard angle limits of the open timing IVO and the close timing EVC that can ensure combustion stability in the operation state at that time. In other words, the limit values LIVO are open. The allowable minimum value of the timing IVO is indicated, and the limit value LEVC indicates the allowable maximum value of the closing timing EVC.
The limit values LIVO and LEVC are preliminarily adapted based on the result of an experiment for detecting changes in combustion stability when the opening timing IVO and the closing timing EVC are changed. For example, the engine load, the engine speed, Is stored in a map with.

  Here, when the opening timing IVO of the intake valve 105 advances beyond the limit value LIVO (when the opening timing IVO <the limit value LIVO), and / or when the closing timing EVC of the exhaust valve 107 is the limit value. When retarding beyond LEVC (when closing timing EVC> limit value LEVC), in other words, when the valve overlap amount exceeds the allowable limit in the operating conditions at that time, Estimated to be unstable beyond acceptable limits.

  On the other hand, when the opening timing IVO of the intake valve 105 is more retarded than the limit value LIVO (when the opening timing IVO ≧ limit value LIVO), and when the closing timing EVC of the exhaust valve 107 is higher than the limit value LEVC. Is also advanced (when closing timing EVC ≦ limit value LEVC), in other words, when the valve overlap amount is smaller than the allowable limit in the operating conditions at that time, the necessary and sufficient combustion stability Is estimated to be secured.

In step S4, the actual opening timing IVO of the intake valve 105 at the current time is greater than or equal to the limit value LIVO (actual opening timing IVO ≧ limit value LIVO), and the actual closing timing EVC of the exhaust valve 107 at the current time is less than or equal to the limit value LEVC. It is determined whether (actual closing timing EVC ≦ limit value LEVC).
The actual opening timing IVO includes the actual valve operating angle of the intake valve 105 obtained from the rotation angle of the control shaft 13 detected by the angle sensor 134, and the intake valve 105 detected by the crank angle sensor 117 and the cam sensor 132. It is a value calculated from the actual center phase (the rotational phase of the intake camshaft 3 with respect to the crankshaft 120). Like the predicted opening timing IVO, the opening timing IVO before the top dead center TDC is indicated by a negative angle. The opening time after the top dead center TDC is indicated by a positive angle.

  On the other hand, the actual closing timing EVC is an actual center phase of the exhaust valve 107 detected by the crank angle sensor 117 and the cam sensor 133 (the rotational phase of the exhaust camshaft 110 with respect to the crankshaft 120) and the exhaust valve 107 having a constant value. As with the predicted closing timing EVC, the closing timing EVC before the top dead center TDC is indicated by a negative angle, and the closing timing after the top dead center TDC is a positive value. Shown in angle.

If the actual opening timing IVO of the intake valve 105 at the current time is not less than the limit value LIVO and the actual closing timing EVC of the exhaust valve 107 at the current time is not more than the limit value LEVC, step S5 is bypassed and step S6 is bypassed. Proceed to
That is, whether the actual opening timing IVO of the intake valve 105 coincides with the limit value LIVO, or is retarded from the limit value LIVO, and the actual closing timing EVC of the exhaust valve 107 coincides with the limit value LEVC. When it is on the more advanced side than the value LEVC, it is determined that the combustion stability can be secured by the operation at the actual opening timing IVO and the actual closing timing EVC at the current time, and the actual opening timing IVO and the actual closing timing EVC are determined. The process proceeds to step S6 without performing the process for changing.

On the other hand, when the actual opening timing IVO of the intake valve 105 at the current time is less than the limit value LIVO and / or when the actual closing timing EVC of the exhaust valve 107 at the current time exceeds the limit value LEVC, Proceed to step S5 to change the actual opening timing IVO and the actual closing timing EVC.
That is, when the actual opening timing IVO of the intake valve 105 is on the more advanced side than the limit value LIVO and / or when the actual closing timing EVC of the exhaust valve 107 is on the more retarded side than the control value LEVC, In the operation at the actual opening timing IVO and the actual closing timing EVC at the current time, there is a possibility that the valve overlap is excessive and the combustion becomes unstable. Therefore, the actual opening timing IVO / actual closing timing EVC is the limit values LIVO, LEVC. In order not to exceed, the process proceeds to step S5.

When the actual opening timing IVO of the intake valve 105 is more advanced than the limit value LIVO (actual opening timing IVO <limit value LIVO), in step S5, the target value limit value of the lift / operating angle variable mechanism 112 is set. The operating angle target limit value (maximum valve operating angle) is set as follows.
Operating angle target limit value = (center phase at the most retarded angle−advance amount manipulated variable−LIVO) × 2
The “center phase at the most retarded angle” is the center phase of the intake valve 105 in the initial state (OFF state) of the center phase variable mechanism 113a, and is indicated by an angle from the top dead center TDC.

The advance angle manipulated variable is a change amount of the advance angle of the center phase due to the operation of the center phase variable mechanism 113a, and “center phase at the most retarded angle−advance angle manipulated variable” is obtained by increasing the center phase at the current time. This is indicated by the angle from the dead center TDC.
The result of subtracting the limit value LIVO from the center phase at the current time of the intake valve 105 is a value half the valve operating angle at which the opening timing IVO coincides with the limit value LIVO in the actual center phase at that time. By doubling this, the valve operating angle at which the opening timing IVO coincides with the limit value LIVO is obtained at the actual center phase at that time, and the valve operating angle is set as the operating angle target limit value (maximum valve operating angle). To do.

Here, if the valve operating angle is controlled below the target operating angle limit value (maximum valve operating angle), the opening timing IVO does not advance beyond the limit value LIVO.
Therefore, the target value (target valve operating angle) of the lift / operating angle variable mechanism 112 at that time is compared with the operating angle target limit value (maximum valve operating angle), and the lift / operating angle variable mechanism 112 at that time is compared. When the target valve operating angle exceeds the operating angle target limit value, the operating angle target limit value is set to the target value of the lift / operating angle variable mechanism 112.

That is, the target valve operating angle of the lift / operating angle variable mechanism 112 is limited to the upper limit value or less using the operating angle target limit value as the upper limit value.
Therefore, for example, when the central phase of the valve operating angle of the intake valve 105 is retarded and the valve lift amount / valve operating angle is increased and changed, the central phase is actually delayed and the limit value LIVO and the central phase are changed. When the angle between is increased, the operating angle target limit value becomes larger, and a larger value is allowed to be set as the target value of the valve operating angle.

  In the present embodiment, the time constant of the center phase variable mechanism 113a is larger than the time constant of the lift / operating angle variable mechanism 112, for example, the center phase of the valve operating angle of the intake valve 105 is retarded, and the valve lift When increasing the amount and valve operating angle, the increase in valve lift amount and valve operating angle is preceded, followed by the delay change in the center phase, and the center phase is sufficiently delayed. If the valve operating angle becomes large in a state where the intake valve is not operated, the opening timing IVO of the intake valve 105 may transiently advance beyond the limit value LIVO.

Therefore, a larger valve operation angle target is allowed to be set as the center phase is retarded so as to increase the valve operation angle in response to a change in the center phase with a large response time constant. It is.
As described above, if the target of the valve operating angle is limited to be small, the opening phase IVO of the intake valve 105 is suppressed or prevented from advancing beyond the limit value LIVO transiently, while the center phase is The valve operating angle / valve lift amount can be continuously increased in response to the change in the retard angle, and the torque response (acceleration response) is not greatly deteriorated.

  When the response time constant of the center phase variable mechanism 113a is smaller than the response time constant of the lift / operation angle variable mechanism 112, for example, when the valve lift amount is reduced and the center phase is advanced simultaneously. The valve lift decreases with respect to the advance angle of the center phase, and the center phase advances to the target, but the valve lift decreases with a delay, and the opening timing IVO of the intake valve 105 becomes transient. There is a possibility of advancing beyond the limit value LIVO.

Therefore, in the case of the above characteristics, the opening timing IVO of the intake valve 105 is made transient by restricting the change of the advance angle target of the center phase to be equal to or less than the advance angle amount corresponding to the actual decrease in the valve lift. Therefore, it is possible to inhibit or prevent the valve angle from being advanced beyond the limit value LIVO, in other words, the valve overlap from exceeding the allowable limit.
That is, of the lift / operating angle variable mechanism 112 and the center phase variable mechanism 113a, the mechanism having the smaller response time constant (the faster response side) is limited in its target value, so that the response on the slower response side is limited. Corresponding to the change in the control amount, one of them does not change the control amount in advance.

On the other hand, when the actual closing timing EVC of the exhaust valve 107 is on the retard side with respect to the control value LEVC, the center phase limit that is the limit value of the target value (target retard amount) of the exhaust-side center phase variable mechanism 113b. Set the value (maximum retard amount) as follows.
Center phase limit value = limit value LEVC−EVC at the most advanced angle
The closing timing EVC of the exhaust valve 107 is indicated by an angle from the top dead center TDC, and is indicated as a negative value before the top dead center TDC and a positive value after the top dead center TDC. The amount of retardation change from EVC at the advance angle to the limit value LEVC is shown. In other words, the center phase limit value is the center phase variable mechanism 113b for making the closing timing EVC of the exhaust valve 107 coincide with the limit value LEVC. This is the target for retarding the angle.

Then, the center phase limit value is compared with the retardation target of the center phase in the center phase variable mechanism 113b. When the retardation target is larger than the center phase limit value, the center phase is set as the retardation target. A limit value is set, and the retardation target of the center phase in the center phase variable mechanism 113b is limited to be equal to or less than the center phase limit value (maximum retardation amount).
As a result, it is possible to suppress or prevent the closing timing EVC of the exhaust valve 107 from being transiently retarded beyond the limit value LEVC, in other words, the valve overlap becoming larger than the allowable limit.

Note that when the actual opening timing IVO of the intake valve 105 is on the more advanced side than the limit value LIVO and the actual closing timing EVC of the exhaust valve 107 is on the more retarded side than the control value LEVC, the operating angle Both restriction of the control target of the lift / operating angle variable mechanism 112 by the target limit value and restriction of the control target of the center phase variable mechanism 113b by the center phase limit value are executed.
In step S6, it is determined whether the predicted opening timing IVO predicted in step S2 is equal to or greater than the limit value LIVO, and the predicted closing timing EVC predicted in step S2 is equal to or less than the limit value LEVC.

The predicted opening timing IVO and the predicted closing timing EVC are angles from the top dead center TDC, and are indicated by a negative angle before the top dead center TDC, and are indicated by a positive angle after the top dead center TDC.
If the predicted opening timing IVO of the intake valve 105 is equal to or greater than the limit value LIVO and the predicted closing timing EVC of the exhaust valve 107 is equal to or less than the limit value LEVC, step S7 is bypassed and this routine is terminated.

  That is, the predicted opening timing IVO of the intake valve 105 coincides with the limit value LIVO, or is behind the limit value LIVO, and the estimated closing timing EVC of the exhaust valve 107 matches the limit value LEVC. Or if it is more advanced than the control value LEVC, it will be determined that there will be no temporary increase in valve overlap that will impair combustion stability in the future. There are no restrictions.

On the other hand, if the predicted opening timing IVO of the intake valve 105 is less than the limit value LIVO and / or if the predicted closing timing EVC of the exhaust valve 107 exceeds the limit value LEVC, step S7 (operation limiting means) Proceed to and limit the control target.
That is, when the predicted opening timing IVO of the intake valve 105 is on the more advanced side than the limit value LIVO and / or when the predicted closing timing EVC of the exhaust valve 107 is on the more retarded side than the control value LEVC, Since it is predicted that the valve overlap will become excessive in the future and the combustion will become unstable, the process proceeds to step S7 in order to prevent the actual opening timing IVO / actual closing timing EVC from exceeding the limit values LIVO, LEVC. The control target is limited in advance.

Since the restriction of the control target in step S7 is performed in the same manner as in step S5, detailed description will be omitted below.
When the predicted opening timing IVO of the intake valve 105 is more advanced than the limit value LIVO, the limit value of the target value of the lift / operating angle variable mechanism 112 is set as follows.
Operating angle target limit value = (center phase at the most retarded angle−advance amount manipulated variable−LIVO) × 2
Then, the target value of the lift / operating angle variable mechanism 112 at that time is compared with the operating angle target limit value, and the target valve operating angle of the lift / operating angle variable mechanism 112 at that time is determined as the operating angle target limit. When the value exceeds the value, the operating angle target limit value is set to the target value of the lift / operating angle variable mechanism 112.

That is, a process for limiting the target value of the lift / operating angle variable mechanism 112 to the upper limit value or less is performed using the operating angle target limit value as the upper limit value.
Therefore, for example, when the central phase of the valve operating angle of the intake valve 105 is retarded and the valve lift amount / valve operating angle is increased and changed, the central phase is actually delayed and the limit value LIVO and the central phase are changed. When the angle between is increased, the operating angle target limit value becomes larger, and a larger value is allowed to be set as the target value of the valve operating angle.

  As described above, if the target value of the lift / operating angle variable mechanism 112 is limited based on the predicted opening timing IVO, in anticipation that the opening timing IVO will advance beyond the limit value LIVO in the future, Since the target value is limited, there is no delay as in the case of adding a limit after detecting that the angle has actually advanced beyond the limit value LIVO, and processing for preventing the limit value LIVO from being exceeded. Since it can be started from an earlier time, it is possible to suppress or prevent the opening time IVO from being advanced beyond the limit value LIVO more reliably and effectively.

If the opening timing IVO can be prevented or prevented from advancing beyond the limit value LIVO, the valve overlap can be prevented or prevented from being excessively increased, and combustion stability during transient operation can be maintained. it can.
When the time constant of the center phase variable mechanism 113a is smaller than the time constant of the lift / operating angle variable mechanism 112, the advance target of the center phase is limited to an amount of advance corresponding to the actual decrease in the valve lift. Thus, it is possible to suppress or prevent the opening timing IVO of the intake valve 105 from being advanced beyond the limit value LIVO in the future.

On the other hand, when the predicted closing timing EVC of the exhaust valve 107 is behind the control value LEVC, the limit value of the target value of the center phase variable mechanism 113b on the exhaust side is set as follows.
Center phase limit value = limit value LEVC−EVC at the most advanced angle
Then, the central phase limit value is compared with the retardation target of the central phase in the central phase variable mechanism 113b. If the retardation target is larger than the central phase limit value, the retardation target is set to the central phase. The limit value is set, and the retardation target of the center phase in the center phase variable mechanism 113b is restricted below the center phase limit value (maximum retardation amount).

  Also in this case, it is predicted that the closing timing EVC of the exhaust valve 107 is retarded from the control value LEVC, and the delay target of the center phase in the center phase variable mechanism 113b is limited, so that the actual closing timing EVC is controlled. Since there is no delay as in the case of adding a limit after detecting that the angle is retarded from the value LEVC, the processing for preventing the limit value LEVC from exceeding the limit value can be started at an earlier time, so that the more reliable In addition, it is possible to suppress or prevent the closing timing EVC from retarding beyond the limit value LEVC.

As described above, if it is possible to prevent or prevent the opening timing IVO from being advanced beyond the limit value LIVO and the closing timing EVC from being retarded beyond the limit value LEVC, it can be transiently achieved. Excessive valve overlap can be prevented or prevented, and combustion stability during transient operation can be maintained.
When the predicted opening timing IVO of the intake valve 105 is on the more advanced side than the limit value LIVO and the predicted closing timing EVC of the exhaust valve 107 is on the more retarded side than the control value LEVC, the operating angle Both restriction of the control target of the lift / operating angle variable mechanism 112 by the target limit value and restriction of the control target of the center phase variable mechanism 113b by the center phase limit value are executed.

The flowchart of FIG. 8 shows a program for controlling the continuation / cancellation regarding the restriction of the control target of the lift / operation angle variable mechanism 112 and the restriction of the control target of the center phase variable mechanism 113b.
In step S11, the result of subtracting the margin allowance α (> 0) from the actual opening timing IVO is equal to or greater than the limit value LIVO, and the result of adding the margin allowance β (> 0) to the actual closing timing EVC is the limit. It is determined whether or not the value is less than LEVC.

The larger the value of the actual opening timing IVO, the slower the opening timing IVO of the intake valve 105. Therefore, when the actual opening timing IVO−the margin allowance α ≧ the limit value LIVO is established, the limit value LIVO is indicated. The actual opening timing IVO is retarded more than the margin allowance α than the advance angle limit of the opening timing IVO.
In other words, even if the advance angle is further advanced by the margin allowance α, the actual open timing IVO does not exceed the limit value LIVO, and the advance allowance greater than the allowance allowance α remains.

Further, the smaller the value of the closing timing EVC, the earlier the closing timing EVC of the exhaust valve 107 is. Therefore, when the limit value LEVC ≧ actual closing timing EVC + the margin allowance β is satisfied, the limit value LEVC is indicated. The actual closing timing EVC is advanced more than the margin β beyond the delay limit of the closing timing EVC.
In other words, even if the delay is further delayed by the margin allowance β from the actual closing timing EVC, the actual closing timing EVC does not exceed the limit value LEVC, and the delay allowance greater than the margin allowance β remains.

  As described above, when the actual opening timing IVO and the actual closing timing EVC do not exceed the limit values and are sufficiently separated from the limit values LIVO and LEVC, the routine proceeds to step S12, where the lift / operation angle is increased. The restriction of the control target of the variable mechanism 112 and the restriction of the control target of the center phase variable mechanism 113b are canceled, and the control target set according to the engine operating condition is used as it is, and the variable lift / operation angle mechanism 112 and the center The phase variable mechanism 113b is controlled.

On the other hand, if the actual opening timing IVO−the margin allowance α <the limit value LIVO and / or the limit value LEVC <the actual closing timing EVC + the margin allowance β, the process proceeds to step S13 to control the lift / operating angle variable mechanism 112. The target restriction and the control target restriction of the center phase variable mechanism 113b are continued.
That is, when the actual opening timing IVO is advanced beyond the limit value LIVO, the actual opening timing IVO is retarded from the limit value LIVO, but when the amount of retardation is smaller than the margin allowance α, When the closing timing EVC is delayed more than the limit value LEVC, any of the cases where the actual closing timing EVC is on the more advanced side than the limit value LEVC but the amount of advance is smaller than the margin allowance β While one is established, the control target limitation of the lift / operation angle variable mechanism 112 and the control target limitation of the center phase variable mechanism 113b are continued.

  Therefore, as a result of limiting the control target, even if the actual opening timing IVO is retarded from the limit value LIVO and the actual closing timing EVC is advanced from the limit value LEVC, the limitation is not immediately released. The limit is released after sufficiently separating from the limit values LIVO, LEVC, and the actual opening timing IVO is advanced again to the limit value LIVO or / or the actual closing timing EVC is retarded to the limit value LEVC or more. If this happens, limit the control target.

Thereby, it can suppress that frequent switching (hunting) generate | occur | produces between the state in which a control target is restrict | limited, and the state in which the restriction | limiting of a control target is cancelled | released.
Further, by determining whether to continue or cancel the restriction of the control target based on the actual opening timing IVO and the actual closing timing EVC, the actual opening timing IVO is advanced to the limit value LEVC or more. It can be reliably prevented that the EVC is retarded beyond the limit value LEVC.

  When the restriction release is determined based on whether the predicted opening timing IVO or the predicted closing timing EVC is sufficiently away from the limit value, the future opening timing IVO and closing timing EVC are determined from the operation amount based on the control target to which the limitation is added. Therefore, the restriction is released in a state where the actual opening timing IVO or closing timing EVC has not caught up with the predicted value, and when the restriction release is determined, the actual opening timing IVO and / or actual closing timing are released. There is a possibility that the timing EVC exceeds the limit value.

For this reason, when the restriction release is determined from the predicted value, there is a possibility that the restriction of the control target is once released in a state where the actual opening timing IVO and the actual closing timing EVC exceed the limitation values. is there.
On the other hand, if it is determined whether or not the restriction of the control target is released based on the actual opening timing IVO and the actual closing timing EVC, the opening timing IVO / closing timing EVC is actually limited by the limitation of the control target. After the value does not exceed the value, the restriction on the control target is released, and the restriction release can be appropriately determined.

The margins α and β are adapted based on the results of experiments and simulations in advance so as to avoid excessive control target restriction while preventing control hunting. And the margin allowance β may be set to the same value, the allowance allowance α and the allowance allowance β may be set to different values, and may be set variably according to the operating state of the engine.
In the above-described embodiment, in the internal combustion engine 101, both the intake valve 105 and the exhaust valve 107 are provided with variable valve mechanisms. However, the variable valve mechanism is provided only in either the intake valve 105 or the exhaust valve 107. An organization equipped with

  Further, as a means for restricting the operation of the variable valve mechanism so that the valve timing (open timing IVO, close timing EVC) does not exceed the limit value, the control target is limited / corrected. In addition, it includes changes and corrections in the manipulated variable and control gain, correction of the detection result of the controlled variable (lift amount and rotational phase), and use for feedback control. This includes stopping the operation, driving the variable valve mechanism in a direction opposite to the direction approaching the control target, and applying a brake to the operation toward the control target.

  Further, when the operation of the variable valve mechanism is limited so that the valve timing (open timing IVO, closing timing EVC) does not exceed the limit value, especially when the operation is limited during acceleration, the cylinder intake air amount increases. In the case where the acceleration response is hindered and lower than that in the non-restricted state, the acceleration can be increased and the acceleration response can be maintained by performing advance correction of the ignition timing, increase correction of the fuel injection amount, and the like.

The system figure of the internal combustion engine for vehicles in an embodiment. The perspective view which shows the variable valve mechanism of the intake valve in embodiment. The figure which shows the lift and the working angle variable mechanism in embodiment. The figure which shows the center phase variable mechanism in embodiment. The diagram which shows the change characteristic of the center phase of the lift of the intake valve in the embodiment, the valve operating angle, and the valve operating angle. The diagram which shows the change of the valve timing at the time of operating the lift and working angle variable mechanism and center phase variable mechanism in embodiment. The flowchart which shows the restriction | limiting process of the control target of the lift and working angle variable mechanism and center phase variable mechanism in embodiment. The flowchart which shows the cancellation | release process of the restriction | limiting of the control target of a lift and a working angle variable mechanism and a center phase variable mechanism in embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 3 ... Intake camshaft, 13 ... Control shaft, 99 ... Electromagnetic actuator, 101 ... Internal combustion engine, 104 ... Electronically controlled throttle, 105 ... Intake valve, 107 ... Exhaust valve, 112 ... Lift / operating angle variable mechanism, 113a, 113b ... Center phase variable mechanism, 114 ... engine control unit, 116 ... accelerator pedal sensor, 117 ... crank angle sensor, 120 ... crankshaft, 132 ... intake cam sensor, 133 ... exhaust cam sensor, 134 ... angle sensor

Claims (5)

A variable valve control apparatus for an internal combustion engine comprising a variable valve mechanism for continuously changing an opening characteristic of an engine valve,
Predicting means for predicting a change in a control amount of the variable valve mechanism based on an operation amount of the variable valve mechanism;
Operation limiting means for limiting the operation of the variable valve mechanism so that the control amount does not exceed the limit value when the predicted control amount exceeds a limit value;
A variable valve control apparatus for an internal combustion engine, comprising:   The variable motion of the internal combustion engine according to claim 1, wherein the predicting means predicts a change in the control amount based on a transfer function indicating a relationship between an operation amount and a control amount in the variable valve mechanism. Valve control device.   The variable valve control apparatus for an internal combustion engine according to claim 1 or 2, wherein the control amount predicted by the predicting means is an opening timing of the intake valve and / or a closing timing of the exhaust valve. The variable valve mechanism includes a center phase variable mechanism that continuously varies the center phase of the valve operating angle of the engine valve, and an operating angle variable mechanism that continuously varies the valve operating angle of the engine valve. ,
The predicting means predicts a valve timing of the engine valve at which an opening characteristic is variable by the center phase variable mechanism and the operating angle variable mechanism;
When the predicted valve timing exceeds a limit value, the operation limiting means changes a target value of a variable mechanism having a smaller response time constant among the central phase variable mechanism and the operating angle variable mechanism. The variable valve control apparatus for an internal combustion engine according to any one of claims 1 to 3, wherein the variable valve control apparatus is limited to a small value.   The operation limiting means is configured to change a variable mechanism having a smaller response time constant according to a change in a control amount in a variable mechanism having a larger response time constant of the central phase variable mechanism and the operating angle variable mechanism. 5. The variable valve control apparatus for an internal combustion engine according to claim 4, wherein a limit amount of the target value is changed.

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