JP2009209732A - Control device and control method for internal combustion engine with variable valve train - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent apparent conversion angle change and deterioration of controllability in valve timing control due to slippage of a dead band median of a solenoid valve. <P>SOLUTION: A controlled variable operation means 70 includes a base controlled variable calculation means B5 calculating base controlled variables based on target phase difference, a feedback compensation part B6 calculating compensation quantity for compensating base controlled variable based on a value provided by integrating the deviation, an initial value operation means B4 operating an initial value for initializing the value provided by integrating the deviation when the target phase difference changes from a state regulated by the phase difference regulation means to a states other than that, and an actual phase range judgment means B3 judging whether an actual phase difference is in a range in which the phase difference regulation means can control the actual phase difference the same can be regulated. The initial value operation means B4 sets a value equivalent to the value provided by integrating the deviation when the actual phase changes in a range in which the actual phase difference cannot be controlled by the phase difference regulation means to an initial value. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a variable valve mechanism control apparatus for an internal combustion engine.

A variable valve mechanism that controls the opening / closing timing of the intake valve or exhaust valve by changing the relative angle (conversion angle) between the camshaft of the internal combustion engine and the sprocket for driving the camshaft using hydraulic pressure. Is known (Patent Document 1). Specifically, for the purpose of quickly converging the actual conversion angle (actual conversion angle) to the target conversion angle immediately after the start of energization of the control device, feedback control means with integration is provided to correct the control amount. Of the correction amount to be corrected, the correction amount by the integrator is learned, and immediately after the energization is started, the integrator is initialized with this learning value.
Japanese Patent No. 3068806

  Incidentally, the three-position solenoid valve used for hydraulic control of the variable valve mechanism has a dead zone in which no speed is generated with respect to current. For this reason, in Patent Document 2, the current corresponding to the center of the dead zone is added to the calculated value of the feedback control means to obtain the control current of the solenoid valve. The current corresponding to the center of the dead zone of the solenoid valve varies due to individual differences. However, in Patent Document 2, the integrator accumulates the deviation between the actual conversion angle and the target conversion angle caused by the variation. The variation of the valve is corrected.

  On the other hand, in a variable valve mechanism, combustion fluctuations occur between the generation of a crankshaft sensor signal and the generation of a camshaft sensor signal, or the chain that links the camshaft and crankshaft is bent. Even if the rotational speeds of both shafts change and the actual conversion angle does not change, the conversion angle may change and appear to be detected. For this reason, for example, when the target conversion angle is the most retarded position where the target conversion angle is mechanically regulated, the target conversion angle is apparently reached even though the target conversion angle is actually reached. A situation can occur that does not.

  In Patent Document 2, in such a case, the integrated value of the apparent deviation between the actual conversion angle and the target conversion angle is accumulated in the integrator, and the erroneous integration value is stored as a learning value. . Therefore, there is a problem that the control performance deteriorates by performing initialization based on the learning value.

  In addition, simply initializing the integrator to zero cannot correct the current variation corresponding to the center of the dead zone of the solenoid valve described above, so that the control performance deteriorates immediately after initialization. It cannot be avoided.

  Therefore, in the present invention, feedback control is performed so as to eliminate the influence of unnecessary integral accumulation when the apparent conversion angle changes and to correct the variation in current corresponding to the center of the dead zone of the solenoid valve. The purpose is to initialize the integral term of the means.

  The control device for an internal combustion engine with a variable valve mechanism according to the present invention detects a phase difference adjusting means capable of changing a valve timing by adjusting a phase difference between a crankshaft and a camshaft of the internal combustion engine and a phase of the crankshaft. Crankshaft phase detecting means, camshaft phase detecting means for detecting the phase of the camshaft, phase difference regulating means provided for mechanically regulating the maximum and minimum values of the phase difference, and the engine operating state Target phase difference setting means for setting a target phase difference according to the actual phase difference detection means for calculating a deviation between a detection value of the crankshaft phase detection means and a detection value of the camshaft phase detection means as an actual phase difference; A variable valve mechanism comprising: a control amount calculation unit that calculates a control amount input to the phase difference adjustment unit so that a deviation between the target phase difference and the actual phase difference becomes zero The control amount calculation means includes a basic control amount calculation means for calculating a basic control amount based on the target phase difference, and a value obtained by integrating a deviation between the target phase difference and the actual phase difference. A feedback correction unit that calculates a correction amount for correcting the basic control amount based on the target phase difference and the target phase difference when the target phase difference changes from a state regulated by the phase difference regulation unit to an unregulated state. An initial value calculating means for calculating an initial value for initializing a value obtained by integrating the deviation from the phase difference, and whether or not the actual phase difference is within a range that can be regulated by a preset phase difference regulating means. And an initial value calculating means for calculating a deviation between the target phase difference and the actual phase difference when the actual phase difference changes within a range that cannot be regulated by the phase difference regulating means. The value corresponding to the integrated value is set as the initial value.

  According to the present invention, as the initial value of the integral term of the feedback correction means, a value that corrects the characteristic deviation of the current corresponding to the center of the dead zone can be set. Even if the upper conversion angle changes, the integral term of the feedback control means is initialized so that the influence of unnecessary integral accumulation can be removed and the variation in current corresponding to the center of the dead zone of the solenoid valve can be corrected. Can be

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of an embodiment of a control device for a variable valve mechanism (hereinafter referred to as “VTC”) according to the present invention. Reference numeral 1 denotes a VTC control device as phase difference adjusting means, 30 denotes a VTC, 40 denotes a solenoid valve, 41 denotes an oil pump, 45 denotes an oil pan, and 70 denotes a controller.

  The VTC control device 1 includes a controller 70 as a target phase difference setting unit and a control amount calculation unit, and a solenoid valve 40. The solenoid valve 40 switches the oil path and adjusts the amount of hydraulic oil supplied to the VTC 30. Thus, the conversion angle θ of the VTC 30 is controlled.

  The VTC 30 includes a camshaft 31 and a camshaft drive sprocket 33 that is coaxial with the camshaft 31 and rotates synchronously with an engine crankshaft (not shown) via a belt or chain. By changing the relative phase angle (conversion angle) between the shaft 31 and the camshaft drive sprocket 33, the opening / closing timing of an intake valve or an exhaust valve (not shown) is controlled to advance / delay.

  The camshaft 31 includes a plurality of (three in FIG. 1) vanes 32 that rotate integrally with the camshaft 31.

  The camshaft drive sprocket 33 is provided with a space that allows the vane 32 to rotate. This space is made up of an advance hydraulic chamber 33a and a retard hydraulic chamber 33b by the vane 32.

  The advance hydraulic chamber 33a is connected to a passage switching solenoid valve 40 via an advance oil passage 43a. The retard hydraulic chamber 33b is connected to a solenoid valve 40 for switching the passage via a retard oil passage 43b.

  In addition to the advance oil passage 43a and the retard oil passage 43b, the solenoid valve 40 includes an oil supply passage 42 provided with an oil pump 41 that pumps hydraulic oil of the oil pan 45 along the way, A drain passage 44 for returning the hydraulic oil is connected.

  The VTC control device 1 changes and holds the hydraulic pressure to the advance hydraulic chamber 33a and the retard hydraulic chamber 33b as appropriate by changing the oil passage by controlling the energization amount to the solenoid valve 40, and changing the conversion angle. Hold. As a result, the VTC 30 performs advance / retard control of the opening / closing timing (valve timing) of the intake valve or the exhaust valve.

  Specifically, when the energization amount to the solenoid valve 40 is increased, the passage is switched to the passage A, and the hydraulic oil in the oil pan 45 is supplied to the advance hydraulic chamber 33a through the advance oil passage 43a. On the other hand, the hydraulic oil in the retarded hydraulic chamber 33 b is discharged to the oil pan 45 through the retarded oil passage 43 b and the drain passage 44. Thereby, the hydraulic pressure in the advance hydraulic chamber 33a becomes relatively high, and the valve timing is advanced.

  Further, when the energization amount to the solenoid valve 40 is decreased, the operation is switched to the passage B, and the hydraulic oil in the oil pan 45 is supplied to the retard hydraulic chamber 33b through the retard oil passage 43b. On the other hand, the hydraulic oil in the advance hydraulic chamber 33 a is discharged to the oil pan 45 through the advance oil passage 43 a and the drain passage 44. As a result, the hydraulic pressure in the retarded hydraulic chamber 33b becomes relatively high, and the valve timing is retarded.

  Control of the energization amount to the solenoid valve 40 is executed by the controller 70. Connected to the controller 70 are a crank angle sensor 71 as a crankshaft phase detection means, a cam angle sensor 72 as a camshaft phase detection means, and a water temperature sensor 73. The crank angle sensor 71 outputs an angle signal of the crankshaft and outputs a reference crank position signal at the reference rotational position of the crankshaft. The cam angle sensor 72 outputs a reference cam shaft position signal at the reference rotation position of the cam shaft 31. The water temperature sensor 73 outputs the engine water temperature.

  The controller 70 calculates an advance angle amount based on the crank angle sensor 71 and the cam angle sensor 72, and uses the advance angle amount as a current conversion angle (hereinafter referred to as “actual conversion angle”) θ of the VTC 30.

Specifically, the camshaft 31 or a member connected to the camshaft 31 is provided with a convex or concave portion to be detected, the detected portion is detected by the cam angle sensor 72, and a rotation signal of the camshaft 31 is output. The actual advance amount is detected based on the phase difference between the camshaft rotation position signal and the reference crank angle position signal from the crank angle sensor 71. This advance amount is detected as an advance amount with respect to a reference position where the rotation of the camshaft 31 is restricted by a mechanical stopper as a phase difference restricting means (here, the restriction position on the most retarded angle side is a reference position). By learning the phase shift of the reference position, the actual advance amount (actual conversion angle θ _now ) is detected with respect to the learned reference position during valve timing control. The mechanical stopper is a mechanism for mechanically regulating the relative phase angle of the camshaft 31 with respect to the crankshaft. That is, the most advanced angle state and the most retarded angle state of the valve timing are states where the camshaft 31 hits the mechanical stopper.

Then, the energization amount to the solenoid valve 40 is controlled so that the actual conversion angle θ _now follows the target conversion angle θ _com set based on the operating condition of the engine.

  FIG. 2 is a control block diagram illustrating functions related to the VTC control of the controller 70. Each block is numbered with a number corresponding to a step number in a flowchart to be described later with B added at the beginning. Details of specific control contents of each block will be described later along a flowchart.

The controller 70 includes a feedforward compensation unit B5 as a basic control amount calculation unit, a feedback compensation unit B6 as a feedback correction unit, a dead zone compensation unit B7, an initial value calculation unit B4 as an initial value calculation unit, and a conversion angle calculation. And outputs a current command value Icom for controlling the solenoid valve 40 based on the target conversion angle θ _com .

The conversion angle calculation unit B2 calculates the actual conversion angle θ _now based on detection signals from the crank angle sensor 71 and the cam angle sensor 72.

The feedforward compensation unit B5 receives the target conversion angle θ _com and calculates a current command value (F / F term) I _comff and a conversion angle reference response θ _ref .

The feedback compensation unit B6 receives the conversion angle reference response θ _ref and the deviation θ _err of the actual conversion angle θ _now , and calculates a current command value (F / B term) I _comfb .

The initial value calculation unit B4 inputs the actual conversion angle θnow and calculates the initial value I _{comfb — nit} of the integral term of the feedback compensation unit B6.

The dead zone compensator B7 converts the current command value I _com into a current command value (F / F term) I _comff , a current command value (F / B term) I _comfb, and a current value (hereinafter referred to as the center of the dead zone). It is calculated as the sum of I _{cntr (referred} to as dead zone center current value). Here, the dead zone is a region of the solenoid valve 40 in which the speed does not change with respect to the current value, that is, as shown in FIG. 8, a conversion angular velocity that changes depending on the movement of the solenoid valve 40 even if the current value is changed. This is the area where does not change.

  FIG. 3 is a flowchart showing a control routine of VTC control executed by the controller 70. The controller 70 repeats this process in a minute time cycle of about 10 ms, for example.

In step S1, the target conversion angle θ _com is set according to the operating conditions. Specifically, a map in which the target conversion angle θ _com is assigned to operating conditions (for example, engine speed and load) is created in advance, and is set by searching for it.

In step S2, the conversion angle calculation unit B2 calculates the actual conversion angle θ _now based on the detection signals of the crank angle sensor 71 and the cam angle sensor 72 as described above.

In step S3, as an actual phase range determination means, it is determined whether or not the actual conversion angle θ _now is within a range that does not conflict with the mechanical stopper. Details of the determination method will be described later.

In step S4, the initial value calculation unit B4 inputs the actual conversion angle θnow as described above, and calculates the initial value I _{comfb — nit} of the integral term of the feedback compensation unit B6. This initial value I _{comfb — nit} is for initializing the integral term of the feedback compensator B6 when the target conversion angle θcom changes from the mechanical stopper position state to other states. Details of the calculation method will be described later.

In step S5, the feed conversion unit B5 inputs the target conversion angle θ _com as described above, and calculates the current command value (F / F term) I _comff and the conversion angle reference response θ _ref . The current command value (F / F term) I _comff is calculated by inputting the target conversion angle θ _com to a transfer function configured by the product of the inverse system of the transfer function of the reference model and the transfer function of the controlled object model. . The conversion angle reference response θ _ref is calculated by inputting the target conversion angle θ _com into the transfer function of the reference model.

In step S6, the feedback compensator B6 inputs the deviation θ _err between the conversion angle reference response θ _ref and the actual conversion angle θ _now as described above, and calculates the current command value (F / B term) I _comfb . . Details of the calculation method will be described later.

In step S7, the dead zone compensation unit B7 _{sets the} current command value I _com to the current command value (F / F term) I _comff , the current command value (F / B term) I _comfb, and the dead zone. The current value corresponding to the center (hereinafter referred to as dead zone center current value) I _cntr is calculated as the sum, and this current command value I _com is output to the solenoid valve 40. Actually, a PWM (Pulse Width Modulation) duty ratio in consideration of the drive voltage and the resistance value of the solenoid valve 40 is calculated so as to realize the drive current, and the solenoid valve 40 is PWM driven.

FIG. 4 is a flowchart of determination as to whether or not it is in the range in contact with the mechanical stopper in step S3 of FIG. The “range that contacts the mechanical stopper” and “the range that does not contact the mechanical stopper” are the range where the mechanical stopper may be contacted and the range where contact is not possible when the target conversion angle θ _com is not the mechanical stopper position. I mean.

A flag fAREA used in this flowchart is a flag indicating a determination result as to whether or not the actual conversion angle θ _now is in a range where it does not contact the mechanical stopper. When it is 1, it indicates that it is in a range where it does not contact the mechanical stopper. When it is zero, it is in the contact area. It is zero at the start of control immediately after the start of energization of the controller 70, such as when the engine is started.

Further, the determination values for determining whether or not the range is in contact with the mechanical stopper are θ _Aout and θ _Ain on the advance side and θ _Lin and θ _Lout on the retard side, respectively, and are provided with hysteresis. These determination values have the following magnitude relationship.

θ _Astop > θ _Aout > θ _Ain > θ _Lin > θ _Lout > θ _Lstop
Here, θ _Astop is the mechanical stopper position on the advance side, and θ _Lstop is the mechanical stopper position on the retard side. Hereinafter, specific contents will be described along each step.

  In step S20, it is determined whether the flag fAREA is zero. As a result of the determination, if the flag fAREA is zero, the process proceeds to step S21. If the flag fAREA is 1, the process proceeds to step S24.

In step S21, the actual conversion angle theta _now makes a determination of whether or not theta _Lin above, when more than theta _Lin to step S22, if theta _Lin smaller proceeds respectively to a step S26.

In step S22, the actual conversion angle theta _now makes a determination of whether or less theta _Ain, in the following cases theta _Ain to step S23, if greater than theta _Ain proceeds respectively to a step S26.

In step S24, the actual conversion angle theta _now makes a determination of whether or not theta _Lout above, when more than theta _Lout to step S25, if theta _Lout smaller proceeds respectively to a step S25.

At step S25, the actual conversion angle theta _now makes a determination of whether or less theta _Aout, the following cases theta _Aout to step S23, if greater than theta _Aout proceeds to step S26.

As a result of the determination in steps S21, S22, S24, and S25, in step S23, the flag fAREA is set to 1 because the actual conversion angle θ _now is not in contact with the mechanical stopper, and in step S26, the flag is determined as being in the range not in contact with the mechanical stopper. Set fAREA to zero.

By the way, as shown in FIG. 7, the cam angle sensor 72 provided on either the deflection of the belt or chain that links the camshaft driving sprocket 33 and the crankshaft, or the camshaft 31 or a member connected to the camshaft 31. The rotational speed of both shafts changes due to variations in the processing accuracy of the detected part of the detected part, and even though the actual conversion angular speed θ _now does not change, it is detected as if the actual conversion angle θ _now has changed. There is a case. Then, when the apparent actual conversion angle θ _now changes, the learning value of the reference position also shifts. FIG. 7 shows the detection signal of the cam angle sensor 72 in the upper stage, and the detection signal of the crank angle sensor 71 in the lower stage.

In the most retarded state (S _CAM1 ), if the detection signal of the cam angle sensor 72 is detected at an advanced timing (S _CAM2 ) due to the deflection of the chain or the like, actually, Even if the actual conversion angle θnow does not change, the reference position apparently shifts by the difference between S _CAM1 and S _CAM2 . Thereby, the learning value of the reference position becomes a larger value than the actual value. When the VTC 30 is operated from this state and the conversion angle is changed so that the detection signal of the cam angle sensor 72 is detected by the _SCAM3 , the actual advance amount is _{SCAM3- SCAM1} , but apparently The advance amount of is S _CAM3 −S _CAM2 . That is, the advance amount calculated based on the detection signal is smaller than the actual advance amount.

Accordingly, the determination values θ _Aout , θ _Ain , θ _Lin , and θ _Lout for determining whether or not to contact the mechanical stopper are obtained by determining the maximum deviation of the learning value of the reference position through experiments and the like, and are set accordingly.

FIG. 5 shows the steps of FIG. 3 for calculating the initial value I _{comfb — nit} of the feedback compensation unit B6 that is initialized when the target conversion angle θcom changes from the mechanical stopper position state to the other state. It is a flowchart of the calculation performed by S4.

  In step S40, it is determined whether or not the flag fAREA is 1. When the flag fAREA is 1, the process proceeds to step S41, and when it is zero, the process ends.

At step S41, among the integral term of the feedback compensation unit B6, and stores the _I comfb _ _tg corresponding to the output of the integrator to the variable _I comfb _ _mp.

In step S42, the filter operation is performed on the variable I _{comfb — mp} , and the output result is set as the initial value I _{comfb — nit} of the integral term of the feedback compensation unit B6. For the filter calculation, a low-pass filter having a time constant sufficiently slower than the output change of the feedback compensation unit B6 is used. As a result, a transient response component such as a response to a disturbance can be removed from the integral term of the feedback compensation unit B6. Therefore, the initial value of the integral term of the feedback compensation unit B6 described later is simply equivalent to the median value of the dead zone. It is possible to set a value in consideration of only the current deviation.

  As described above, when the actual conversion angle θnow is in a range where it does not come into contact with the mechanical stopper, an initial value is calculated by performing a filter operation on a value corresponding to the integral term of the feedback compensation unit B6. On the other hand, when it is in the range where it is not in contact, this processing is not performed, so the output value of the filter calculation is held at the value in the range where it is not in contact with the mechanical stopper.

  FIG. 6 is a flowchart of the calculation of the feedback compensation unit B6 performed in step S6 of FIG.

The feedback compensation unit B6 is configured by PID control as shown in FIG. 2, and with respect to the deviation between the actual conversion angle θ _now calculated in step S2 and the conversion angle reference response θ _ref calculated in step S5, By calculating the PID control, the current command value (F / B term) I _comfb is obtained. Hereinafter, specific contents will be described along each step.

In step S60, a deviation θ _err between the conversion angle reference response θ _ref and the actual conversion angle θ _now is calculated.

In step S61, proportional control is calculated using the deviation θ _err to calculate the proportional term I _{comfb — p} .

In steps S62 and S63, it is determined whether or not the target conversion angle θ _now has changed from the reference position regulated by the mechanical stopper to other positions. If it has changed, it will progress to step S64, and if it has not changed, it will progress to step S65.

In step S64, it initializes the integral term _I comfb _ _tg feedback compensation unit B6 to the initial value _I comfb _ _nit calculated in step S4.

At step S65, it performs integral calculation using a deviation theta _err, calculates an integrated value _I comfb _ _tg.

In step S66, the integral value I _{comfb — tg} is used to perform integral control, and the integral term I _{comfb — i} is calculated.

In step S67, a differential control is performed using the deviation θerr to calculate a differential term I _{comfb — d} .

In step S68, the output I _comfb of the feedback compensation unit B6 is calculated by the following equation (1).

_{I comfb = I comfb _ p +} I comfb _ i + I cofb _ d ··· (1)
As described above, when the target conversion angle θ _com changes from the reference position regulated by the mechanical stopper to other positions, the actual conversion angle θ _now changes within a range that does not contact the preset mechanical stopper. A value corresponding to the integral term of the feedback compensation unit B6 is set as an initial value of the integral term of the feedback compensation unit B6.

  FIG. 9 is a time chart for the conversion angle, the current value, and the integral term for illustrating an example of the effect obtained by executing the control of FIGS. 5 and 6.

In FIG. 9, the conversion angle is represented by crankshaft angle [degCA], for example, the mechanical stopper position is 40 [degCA], and the threshold value for determining whether or not to contact the mechanical stopper is 35 [degCA]. Note that the threshold for determining whether or not the mechanical stopper is in contact with the mechanical stopper is provided with hysteresis as described above in actual calculation, but is omitted in FIG. 9 for simplicity. Further, since there is a deviation between the learning value of the reference position and the current value corresponding to the center of the dead zone, even if the target conversion angle θ _com is the mechanical stopper position (40 [degCA]), the actual conversion angle θ _now is the mechanical stopper position. until not reach, also integral value _I comfb _ itg feedback compensation unit B6 is the situation save up the integration to the minus side.

The actual conversion angle θ _now begins to increase as the target conversion angle θ _com changes to the mechanical stopper position. At time t1, the actual conversion angle θ _now enters a range where it contacts the mechanical stopper, but the actual conversion angle θ _now reaches only 38 [degCA] due to the deviation of the learning value of the reference position. Thereafter, the target conversion angle θ _com changes to a value that does not contact the mechanical stopper, and the target conversion angle θ _com changes to a position other than the mechanical stopper position at time t2.

At this time, when the actual conversion angle θ _now enters the range where it contacts the mechanical stopper at time t1, the variable I _{comfb — tmp} that holds the value corresponding to the integral term of the feedback compensation unit B6 is the value at the time t1. Retained. When the target conversion angle θ _com changes to a position other than the mechanical stopper position at time t2, the integral value I _{comfb — itg} of the feedback compensation unit B6 is _initialized with the integral term I _{comfb — tmp} .

  On the other hand, FIG. 10 is a time chart when the accumulated integral is not initialized in the same situation as FIG. 9, and FIG. 11 is a time chart when the accumulated integral is similarly initialized with zero.

If the actual conversion angle θ _now does not reach the mechanical stopper position that is the target conversion angle θ _com , the integral term continues to accumulate. When this is not initialized, as shown in FIG. 10, followability to nominal response of the actual conversion angle theta _now the case where the target conversion angle theta _com is changed to other than the mechanical stopper is deteriorated.

On the other hand, if the integral term is initialized to zero when the target conversion angle θ _com is changed to a position other than the mechanical stopper position, the accumulated value is accumulated due to the deviation of the current value corresponding to the center of the dead zone as shown in FIG. Since the integral term is lost, the followability to the normative response of the actual conversion angle θ _now when the target conversion angle θ _com changes to a position other than the mechanical stopper position deteriorates.

In contrast, in the present embodiment, while removing the integral that hoarding between time t1 and time t2, include characteristic deviation of equivalent current integrated value _I comfb _ itg feedback compensation unit B6 to the center of the dead zone However, since the initial value is set, it is possible to realize a response with an ideal actual conversion angle θ _now that follows the reference response.

FIG. 12 is a time chart for the conversion angle, current value, and integral term for explaining the effect of the filter processing in step S42 of FIG. Here, the change in the target conversion angle θ _com is the same as in FIG. 9, but it is assumed that the integral term fluctuates.

Before the time t1 when the target conversion angle θ _com is not in contact with the mechanical stopper, the integral term of the feedback compensator B6 has fluctuated, so the variable I _{comfb — tmp} holding the corresponding value also fluctuated. ing. However, since the initialization at _I comfb _ _init subjected to filter processing to a time t2, the variable _I comfb _ _tmp, even if the integral term is changed, the ideal fruit follows the nominal response A response with the conversion angle θ _now can be realized.

FIG. 13 is a time chart for explaining the effect of stopping the filtering process when the target conversion angle θ _com is in a range where it contacts the mechanical stopper. FIG. 14 is a time chart for comparison, and is a time chart illustrating a case where the filter process is not stopped even when the target conversion angle θ _com is in a range where the target conversion angle θ _com is in contact with the mechanical stopper. The change in the target conversion angle θ _com is the same as in FIG. 9 except that a disturbance is input at time t0.

When the actual conversion angle θ _now changes due to the input of disturbance at time t0, the integral term of the feedback compensation unit B6 also changes to compensate for this.

Thereafter, when the filter process is stopped after the actual conversion angle θ _now enters the range where the mechanical stopper contacts the mechanical stopper at time t1, the value I _{comfb — init} after the filter process holds the value at time t1, as shown in FIG. It will be.

On the other hand, if also continue filtering after time t1, as shown in FIG. 14, the value _I comfb _ _init after filtering, variable retained the value corresponding to the integral term of the feedback compensation unit _B6 I comfb _ _mp , converge to. This variable I _{comfb — tmp} is held in a state of being changed under the influence of disturbance input after time t1. Incidentally, the variable _I comfb _ _tmp at time t1 when there is no disturbance input is as shown in FIG.

That is, after the time t1 is towards the initial value _I comfb _ _init in the case of stopping the filtering process, than the initial value _I comfb _ _init when even after the time t1 was continued filtering is less affected by disturbance input.

For this reason, after initializing the integral term at time t2, as is apparent from the comparison between FIG. 13 and FIG. 14, the actual conversion angle is greater in the case of FIG. The response of θ _now is good.

  FIG. 15 is a diagram for explaining an effect in the case where hysteresis is provided in a determination value for determining whether or not the range is in contact with the mechanical stopper. FIG. 16 is a diagram for comparison, and shows a case where hysteresis is not provided.

Both FIG. 15 and FIG. 16 show a case where the target conversion angle θ _com is a value close to the determination value, and the actual conversion angle θ _now varies in the vicinity of the determination value.

When hysteresis is provided in the determination value, the actual conversion angle θ _now is less than the determination value θ _Ain as shown in FIG. 15 after entering the range where the determination value θ _Aout exceeds the determination value θ _Aout and contacts the mechanical stopper at time t1. Otherwise, the flag fAREA remains zero. For this reason, the variable I _{comfb — tmp} that holds the value corresponding to the integral term of the feedback compensation unit B 6 is also constant while holding the value at time t 1, and the initial value I _{comfb — init} obtained by _performing filtering on this _variable Is also constant.

On the other hand, if no hysteresis is provided in the determination value even under the same condition, as shown in FIG. 16, the vehicle enters the range where it does not come into contact with the mechanical stopper at time t2, and the flag fAREA is switched to 1. . Thereafter, the flag fAREA is switched each time the entry to and the withdrawal from the range in contact with the mechanical stopper are repeated at times t3, t4, t5, and t6. For this reason, since the variable I _{comfb — tmp} that holds a value corresponding to the integral term of the feedback compensation unit B6 also varies, the initial value I _{comfb — init} after the filtering also varies and is not stable.

  As described above, by providing hysteresis to the determination value for determining whether or not it is in the range of contact with the mechanical stopper, it is possible to stably prevent the deterioration of responsiveness.

  As described above, in the present embodiment, the following effects can be obtained.

(1) The VTC 30, which can change the valve timing by adjusting the phase difference between the crankshaft and the camshaft 31, the crank angle sensor 71, the cam angle sensor 72, and the maximum and minimum values of the phase difference are mechanically determined. Between the mechanical stopper provided for regulating the engine, the controller 70 for setting the target phase difference (target conversion angle θ _com ) according to the engine operating state, the detected value of the crank angle sensor 71 and the detected value of the cam angle sensor 72 A conversion angle calculation unit B2 that calculates the deviation as an actual phase difference (conversion angle θ _now ), and a control amount that is input to the VTC 30 so that the deviation between the target conversion angle θ _com and the actual conversion angle θ _now is zero. a controller 70 which, in the control device of the variable valve mechanism with an internal combustion engine having a feed-forward to calculate the basic control amount based on the target conversion angle theta _com And償部B5, the feedback compensation unit B6 for calculating a feedback correction amount for correcting the basic control amount based on the deviation between the target conversion angle theta _com and the actual conversion angle theta _now to the integral value, the target conversion angle theta when _{the com} is changed to a state of not being restricted from a restricted state to the mechanical stopper, the target conversion angle theta _com and the initial value _I comfb _ _nit for initializing the integrated value of the deviation between the actual conversion angle theta _now And an initial value calculation unit B4 that determines whether or not the actual conversion angle θ _now is in a range in contact with a preset mechanical stopper. Since the initial value is a value corresponding to the integral term of the feedback compensator B6 when the actual conversion angle θ _now changes within a range not contacting the mechanical stopper, the initial value of the integral term of the feedback compensator B6 age Thus, it is possible to set a value having an effect of correcting the characteristic deviation of the current corresponding to the center of the dead zone. For this reason, even if the contact with the mechanical stopper cannot be recognized due to the reference position learning deviation, it is possible to eliminate the influence of the unnecessary integral accumulation after the contact with the stopper.

  (2) The value corresponding to the integral term of the feedback compensation unit B6 used for initialization is filtered by a low-pass filter having a time constant sufficiently slower than the output change of the feedback compensation unit B6. Since the later value is set as the initial value, a transient response component such as a response to a disturbance can be removed from the integral term of the feedback compensation unit B6. For this reason, since an initial value can be set in consideration of only a current deviation corresponding to the center of the dead zone, the initial value setting accuracy can be improved.

(3) The filter processing is performed only when changing within the range that does not contact the mechanical stopper, and when it is within the range contacting with the mechanical stopper, the value after filtering when changing within the range not contacting the mechanical stopper Therefore, when the actual conversion angle θ _now changes from the range that does not contact the mechanical stopper to the range that contacts the mechanical stopper when the vibration of the integral term of the feedback compensation unit B6 due to disturbance etc. is peak, it is set as the initial value Since the value to be converged does not converge to the vibration peak value of the integral term, it is possible to prevent the initial value setting accuracy from deteriorating.

(4) Since hysteresis is provided in the determination value as to whether or not it is in the range of contact with the mechanical stopper, it is possible to avoid deterioration in initial value setting accuracy when the actual conversion angle θ _now is hunted in the vicinity of the determination value.

  The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims.

It is a system block diagram of the variable valve mechanism to which this embodiment is applied. Control block diagram showing functions related to variable valve mechanism control It is a flowchart which shows the control routine of a variable valve mechanism. It is a flowchart of determination of whether it is the range which contacts a mechanical stopper. It is a flowchart for calculating the initial value _I comfb _ _init. It is a flowchart of the calculation performed in a feedback compensation part. It is a figure which shows the influence on the conversion angle measurement by the learning shift | offset | difference of a reference position. It is a figure which shows an electric current-conversion angle characteristic. The integral term of the feedback compensator is a time chart for explaining the effect of initializing an initial value _I comfb _ _init. It is a time chart when not integrating the integral term of the feedback compensation unit. It is a time chart in the case of initializing the integral term of a feedback compensation part by zero. It is a time chart for demonstrating the effect by filtering an integral term. It is a time chart for demonstrating the effect by stopping a filter process. It is a time chart when not stopping a filter process. It is a figure for demonstrating the effect by providing a hysteresis in the judgment value of whether to contact a mechanical stopper. It is a figure for demonstrating the case where a hysteresis is not provided in the determination value of whether to contact a mechanical stopper.

Explanation of symbols

1 VTC Controller 30 Variable Valve Mechanism (VTC)
31 camshaft 32 vane 33 camshaft drive sprocket 33a advance hydraulic chamber 33b retard hydraulic chamber 40 solenoid valve 41 oil pump 42 oil supply passage 44 drain passage 45 oil pan 70 controller 71 crank angle sensor 72 cam angle sensor 73 water temperature sensor

Claims (5)

A phase difference adjusting means capable of changing the valve timing by adjusting the phase difference between the crankshaft and the camshaft of the internal combustion engine;
Crankshaft phase detecting means for detecting the phase of the crankshaft;
Camshaft phase detecting means for detecting the phase of the camshaft;
A phase difference regulating means provided for mechanically regulating the maximum value and the minimum value of the phase difference;
Target phase difference setting means for setting a target phase difference according to the engine operating state;
An actual phase difference detection means for calculating a deviation between a detection value of the crankshaft phase detection means and a detection value of the camshaft phase detection means as an actual phase difference;
Control amount calculating means for calculating a control amount input to the phase difference adjusting means so that a deviation between the target phase difference and the actual phase difference becomes zero;
In a control device for an internal combustion engine with a variable valve mechanism comprising:
The control amount calculation means includes
Basic control amount calculating means for calculating a basic control amount based on the target phase difference;
Feedback correction means for calculating a correction amount for correcting the basic control amount based on a value obtained by integrating a deviation between the target phase difference and the actual phase difference;
An initial value for initializing a value obtained by integrating a deviation between the target phase difference and the actual phase difference when the target phase difference changes from a state regulated by the phase difference regulating means to a state not regulated. Initial value calculating means for calculating
Real phase range determining means for determining whether or not the actual phase difference is a range that can be regulated by the preset phase difference regulating means;
Have
The initial value calculating means is a value corresponding to a value obtained by integrating a deviation between the target phase difference and the actual phase difference when the actual phase difference changes within a range that cannot be regulated by the phase difference regulating means. Is the initial value, a control device for an internal combustion engine with a variable valve mechanism.   The initial value calculation means is a value obtained by integrating the deviation between the target phase difference and the actual phase difference when the actual phase difference is changing within a range that cannot be restricted by the phase difference restriction means. 2. The variable motion according to claim 1, wherein a filtering process is performed by a low-pass filter having a time constant sufficiently slower than an output change of the feedback correction unit, and a value after the filtering process is set as the initial value. A control device for an internal combustion engine with a valve mechanism.   The initial value calculating means performs the filtering process only when the actual phase difference changes within a range that cannot be regulated by the phase difference regulating means, and is within a range that can be regulated by the phase difference regulating means. 3. The control of an internal combustion engine with a variable valve mechanism according to claim 2, wherein the value after filtering when the phase difference is not controlled by the phase difference control means is held. apparatus.   The control of the internal combustion engine with a variable valve mechanism according to any one of claims 1 to 3, wherein a hysteresis is provided at a boundary value between a range that can be restricted by the phase restricting means and a range that cannot be restricted. apparatus. A phase difference adjusting means capable of changing the valve timing by adjusting the phase difference between the crankshaft and the camshaft of the internal combustion engine;
Crankshaft phase detecting means for detecting the phase of the crankshaft;
Camshaft phase detecting means for detecting the phase of the camshaft;
A phase difference regulating means provided for mechanically regulating the maximum value and the minimum value of the phase difference;
Target phase difference setting means for setting a target phase difference according to the engine operating state;
An actual phase difference detection means for calculating a deviation between a detection value of the crankshaft phase detection means and a detection value of the camshaft phase detection means as an actual phase difference;
With
In a variable valve mechanism control method for an internal combustion engine that calculates a control amount to be input to the phase difference adjusting means so that a deviation between the target phase difference and the actual phase difference becomes zero,
A basic control amount is calculated based on the target phase difference,
The basic control amount is corrected based on a value obtained by integrating a deviation between the target phase difference and the actual phase difference,
When the target phase difference changes from a state regulated by the phase difference regulating means to an unregulated state, and the actual phase difference changes within a range that cannot be regulated by the phase difference regulating means. A variable valve mechanism characterized by initializing a value obtained by integrating the deviation between the target phase difference and the actual phase difference with a value corresponding to a value obtained by integrating the deviation between the target phase difference and the actual phase difference. For controlling an internal combustion engine with a valve.

Images