JP5987682B2 - Control device for internal combustion engine with variable valve mechanism - Google Patents

Description

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

  As a variable valve mechanism that changes the valve characteristics of an engine valve such as an intake valve or an exhaust valve in accordance with the engine operating state, a variable valve mechanism that changes the valve characteristics in a stepless manner (for example, a variable valve mechanism described in Patent Document 1 or the like). Mechanism) is known.

Here, in an internal combustion engine, for example, an intake air amount may be estimated using an air model, and an estimated value of a valve characteristic may be used in estimating the intake air amount.
In the continuously variable type variable valve mechanism, when the target value of the valve characteristic is changed, the target value is gradually changed, so that the actual valve characteristic does not greatly deviate from the target value change. Follow in good condition. Accordingly, the valve characteristic during the change of the valve characteristic is substantially equal to the target value, and the target value that is gradually changed can be used as the estimated value of the valve characteristic during the change of the valve characteristic.

  On the other hand, in addition to the continuously variable type variable valve mechanism, a variable valve mechanism that changes the valve characteristics in stages (for example, a variable valve mechanism described in Patent Document 2) is also known.

JP 2001-263015 A JP 2004-339951 A

  Unlike the continuously variable type variable valve mechanism, the multistage variable variable valve mechanism that changes the valve characteristics in stages, when the target value of the valve characteristics is changed, the target value is greatly changed in steps. Therefore, it is difficult for the actual valve characteristic to quickly follow the target value change. Therefore, in the multistage variable variable valve mechanism, the target value of the valve characteristic itself cannot be an estimated value of the valve characteristic in the middle of changing the valve characteristic, and a new estimation mode needs to be created.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a control device capable of estimating a valve characteristic in the middle of changing a valve characteristic in an internal combustion engine including a multistage variable valve mechanism. There is to do.

Control device for a variable valve mechanism with an internal combustion engine to solve the above problem is to estimate the estimated rate of change of the valve characteristics in the middle changes the valve characteristics based on the engine speed, the valve characteristic before changing the valve characteristics Based on the estimated change speed, the valve characteristic during the change of the valve characteristic is estimated , the difference between the actual change speed of the valve characteristic and the estimated change speed is obtained, and the calculation formula used when estimating the estimated change speed When the estimated change speed is newly estimated after correcting the numerical value of the numerical value so that the difference is reduced and correcting the numerical value of the arithmetic expression, the estimated change is calculated using the arithmetic expression after correcting the numerical value. The speed is estimated .

  In this configuration, the valve characteristics in the middle of changing the valve characteristics are based on the valve characteristics before the valve characteristics are changed and the estimated change speed of the valve characteristics in the middle of changing from the previous valve characteristics to another valve characteristics. I try to estimate.

  Here, a force (hereinafter referred to as an axial force) acting in one axial direction due to the reaction force of the valve spring that biases the engine valve is applied to the control shaft. If the acting direction of this axial force and the drive direction of the control shaft driven by the electric motor are the same, the change speed of the valve characteristic is increased. On the other hand, if the acting direction of the axial force is opposite to the driving direction of the control shaft driven by the electric motor, the change speed of the valve characteristic becomes slow.

As described above, the change speed of the valve characteristic changes under the influence of the axial force, but the magnitude of the axial force tends to change depending on the engine speed. Therefore, in this configuration, it has to be estimated on the basis of the estimated rate of change of the valve characteristics on the engine speed, thereby taking into account the influence of the axial force can be estimated accurately estimated change rate. Therefore, in the multistage variable variable valve mechanism, the valve characteristic during the change of the valve characteristic can be accurately estimated.
Further, the above-described axial force, friction of the control shaft, output torque of the electric motor, and the like have individual differences for each variable valve mechanism. In this regard, according to the same configuration, the numerical value of the arithmetic expression used when estimating the estimated change rate is corrected according to the difference between the actual change rate of the valve characteristic and the estimated change rate. Therefore, such individual differences for each variable valve mechanism are compensated, and the accuracy of the estimated change speed can be increased in each variable valve mechanism.

In the above control device, the estimated change speed is preferably estimated according to the magnitude of the axial force acting on the control shaft, which is a force that changes according to the engine rotational speed.

In the above control device, the estimated change speed is preferably estimated based on the engine speed and the engine temperature.
The estimated change speed of the valve characteristic has a strong correlation with the operation speed of the control shaft, and the operation speed of the control shaft tends to change under the influence of the engine temperature. In this respect, according to the same configuration, the estimated change speed is estimated in consideration of not only the engine rotation speed but also the engine temperature, so that the accuracy of the estimated change speed can be improved. The engine temperature can be substituted by the engine oil temperature, the cooling water temperature, etc., in addition to directly detecting the engine temperature by a sensor or the like.

In the above control device, it is preferable that the estimated change speed is estimated to be faster as the viscosity of the lubricating oil becomes lower as the engine temperature increases.
As the engine temperature increases, the lower the viscosity of the lubricating oil, the smaller the friction when the control shaft operates, so that the operation speed of the control shaft increases and the rate of change in valve characteristics also increases. Therefore, in the same configuration, the estimated change speed is estimated to be faster as the viscosity of the lubricating oil becomes lower as the engine temperature increases, thereby improving the accuracy of the estimated change speed. .

In the above control device, it is preferable that the estimated change speed be estimated as a slower speed as the output torque of the electric motor becomes lower as the engine temperature increases.
When the ambient temperature of the electric motor rises as the engine temperature increases, the electric resistance in the electric motor increases, so that the current flowing in the electric motor decreases and the output torque of the electric motor decreases. When the output torque of the electric motor is reduced in this way, the operation speed of the control shaft is reduced, and the change speed of the valve characteristic is also reduced. Therefore, in this configuration, the estimated change speed is estimated to be slower as the output torque of the electric motor becomes lower as the engine temperature increases, so that the accuracy of the estimated change speed can be improved. Become.

  In the above control device, when the operating direction of the control shaft is opposite to the acting direction of the axial force acting on the control shaft, the axial force is predetermined when the axial force acting on the control shaft is greater than a predetermined value. It is preferable to make the change amount of the valve characteristic smaller than when the value is less than the value.

  When the operating direction of the control shaft and the acting direction of the axial force are reversed, if the valve characteristics are changed significantly when the axial force is very large, the control shaft is driven greatly against the large axial force. Therefore, an excessive load may be applied to the control shaft and the electric motor. In this regard, in this configuration, when the axial force acting on the control shaft is larger than a predetermined value, the change amount of the valve characteristic is reduced, so that an excessive load is not applied to the control shaft or the electric motor. be able to. In the same configuration, when reducing the amount of change in the valve characteristic, for example, a configuration is adopted in which the valve characteristic is changed stepwise toward the target value of the valve characteristic set based on the engine operating state. be able to.

Sectional drawing which shows the structure around the cylinder head of the internal combustion engine in one Embodiment of the control apparatus of the internal combustion engine with a variable valve mechanism. The fracture | rupture perspective view of the variable mechanism part of the embodiment. The schematic diagram of the variable valve mechanism of the embodiment. The figure which shows the profile of the cam provided in the variable valve mechanism of the embodiment. The graph which shows the change aspect of the maximum lift amount by the variable valve mechanism of the embodiment. 6 is a timing chart showing how the virtual target amount, the virtual lift amount, the target lift amount, and the maximum lift amount change when the valve characteristic is changed in the embodiment. The flowchart which shows the process sequence which sets the initial value of virtual lift amount in the embodiment. The flowchart which shows the process sequence which calculates virtual lift amount in the embodiment. The graph which shows the relationship between engine rotational speed and axial force. The graph which shows the relationship between an engine speed and the basic increase amount in the same embodiment. The graph which shows the relationship between an engine speed and the basic reduction amount in the same embodiment. The graph which shows the relationship between oil temperature and an oil coefficient in the same embodiment. The graph which shows the relationship between oil temperature and a motor coefficient in the same embodiment. The timing chart which shows the change aspect of virtual lift amount in the embodiment. The flowchart which shows a series of processing procedures when correct | amending a basic increase amount, a basic decrease amount, an oil coefficient, and a motor coefficient in the modification of the embodiment. The timing chart which shows the change aspect of the virtual target amount in the modification of the embodiment.

Hereinafter, an embodiment of a control device for an internal combustion engine with a variable valve mechanism will be described with reference to FIGS.
As shown in FIG. 1, the internal combustion engine 1 includes a cylinder block 10 and a cylinder head 20 placed above the cylinder block 10.

  A cylindrical cylinder 11 corresponding to the number of cylinders is formed inside the cylinder block 10, and a piston 12 is slidably accommodated in each cylinder 11. A cylinder head 20 is assembled to the upper part of the cylinder block 10, and a combustion chamber 13 is defined by an inner peripheral surface of the cylinder 11, an upper surface of the piston 12, and a lower surface of the cylinder head 20.

  An intake port 21 and an exhaust port 22 communicating with the combustion chamber 13 are formed in the cylinder head 20. The intake port 21 constitutes a part of the intake passage 30. Further, the exhaust port 22 constitutes a part of the exhaust passage 40.

  The intake port 21 is provided with an intake valve 31 as an engine valve that communicates and blocks the combustion chamber 13 and the intake port 21. The exhaust port 22 is provided with an exhaust valve 41 as an engine valve that communicates and blocks the combustion chamber 13 and the exhaust port 22. The valves 31 and 41 are biased in the valve closing direction by the valve spring 24.

  A lash adjuster 25 is provided in the cylinder head 20 corresponding to the valves 31 and 41. A rocker arm 26 is provided between the lash adjuster 25 and the valves 31 and 41. One end of the rocker arm 26 is supported by the lash adjuster 25, and the other end is in contact with the end portions of the valves 31 and 41.

  Further, an intake camshaft 32 and an exhaust camshaft 42 that drive the valves 31, 41 are rotatably supported by the cylinder head 20, respectively. An intake cam 32 a is formed on the intake cam shaft 32, and an exhaust cam 42 a is formed on the exhaust cam shaft 42. The outer peripheral surface of the exhaust cam 42 a is in contact with the roller 26 a of the rocker arm 26 that is in contact with the exhaust valve 41. Thus, when the exhaust camshaft 42 rotates during engine operation, the rocker arm 26 swings about the portion supported by the lash adjuster 25 by the action of the exhaust cam 42a. As the rocker arm 26 swings, the exhaust valve 41 is lifted in the valve opening direction.

  On the other hand, a variable mechanism 300 that changes the valve characteristics of the intake valve 31 is provided for each cylinder between the rocker arm 26 that contacts the intake valve 31 and the intake cam 32a. The variable mechanism unit 300 constitutes a part of the variable valve mechanism 600 and includes an input arm 311 and an output arm 321. The input arm 311 and the output arm 321 are swingably supported around a support pipe 330 fixed to the cylinder head 20. The rocker arm 26 is urged toward the output arm 321 by the urging force of the valve spring 24, and a roller 26 a provided at an intermediate portion of the rocker arm 26 is in contact with the outer peripheral surface of the output arm 321.

  Further, a protrusion 313 is provided on the outer peripheral surface of the variable mechanism portion 300, and a biasing force of a spring 50 fixed in the cylinder head 20 acts on the protrusion 313. Due to the urging force of the spring 50, the roller 311a provided at the tip of the input arm 311 is in contact with the outer peripheral surface of the intake cam 32a. As a result, when the intake camshaft 32 rotates during engine operation, the variable mechanism portion 300 swings around the support pipe 330 by the action of the intake cam 32a. Then, when the rocker arm 26 is pressed by the output arm 321, the rocker arm 26 swings around the portion supported by the lash adjuster 25. The rocking of the rocker arm 26 lifts the intake valve 31 in the valve opening direction.

  A control shaft 340 that is movable along the axial direction is inserted into the support pipe 330. The variable mechanism 300 changes the relative phase difference between the input arm 311 and the output arm 321 around the support pipe 330, that is, the angle θ shown in FIG. 1 by displacing the control shaft 340 in the axial direction.

Next, the configuration of the variable mechanism unit 300 will be described in more detail with reference to FIG.
As shown in FIG. 2, the variable mechanism unit 300 is provided with output units 320 on both sides of the input unit 310.

The housings 314 and 323 of the input unit 310 and the output unit 320 are each formed in a hollow cylindrical shape, and a support pipe 330 is inserted through them.
A helical spline 312 is formed on the inner periphery of the housing 314 of the input unit 310. On the other hand, on the inner periphery of the housing 323 of each output unit 320, a helical spline 322 whose tooth traces are opposite to the helical spline 312 of the input unit 310 is formed.

  A slider gear 350 is disposed in a series of internal spaces formed by the housings 314 and 323 of the input unit 310 and the two output units 320. The slider gear 350 is formed in a hollow cylindrical shape, and is disposed on the outer peripheral surface of the support pipe 330 so as to be able to reciprocate in the axial direction of the support pipe 330 and to be relatively rotatable around the axis of the support pipe 330. ing.

  A helical spline 351 that meshes with the helical spline 312 of the input unit 310 is formed on the outer peripheral surface of the slider gear 350 in the axial center. On the other hand, helical splines 352 that mesh with the helical splines 322 of the output unit 320 are formed on the outer peripheral surfaces of both ends in the axial direction of the slider gear 350.

  A control shaft 340 that is movable in the axial direction of the support pipe 330 is provided inside the support pipe 330. The control shaft 340 and the slider gear 350 are engaged by pins, the slider gear 350 can rotate with respect to the support pipe 330, and the slider gear 350 also moves in the axial direction in accordance with the movement of the control shaft 340 in the axial direction. To do.

  In the variable mechanism section 300 configured as described above, when the control shaft 340 moves in the axial direction, the slider gear 350 also moves in the axial direction in conjunction with the movement of the control shaft 340. Helical splines 351 and 352 formed on the outer peripheral surface of the slider gear 350 have different tooth trace formation directions, respectively, and helical splines 312 and 322 formed on the inner peripheral surfaces of the input unit 310 and the output unit 320, respectively. Meshed. Therefore, when the slider gear 350 moves in the axial direction, the input unit 310 and the output unit 320 rotate in opposite directions. As a result, the relative phase difference between the input arm 311 and the output arm 321 is changed, and the maximum lift amount and the valve opening period that are valve characteristics of the intake valve 31 are changed. Specifically, when the control shaft 340 is moved in the arrow Hi direction shown in FIG. 2, the slider gear 350 is moved in the arrow Hi direction together with the control shaft 340. Accordingly, the relative phase difference between the input arm 311 and the output arm 321, that is, the angle θ shown in FIG. 1 increases, and the maximum lift amount VL and the valve opening period INCAM of the intake valve 31 increase to increase the intake air amount. Increase. On the other hand, when the control shaft 340 is moved in the direction of the arrow Lo shown in FIG. 2, the relative phase difference between the input arm 311 and the output arm 321 becomes smaller as the slider gear 350 moves in the direction of the arrow Lo together with the control shaft 340. . As a result, the maximum lift amount VL and the valve opening period INCAM of the intake valve 31 are reduced, and the intake air amount is reduced.

Next, the configuration of the drive unit that moves the control shaft 340 of the variable valve mechanism 600 in the axial direction will be described.
As shown in FIG. 3, the drive part of the variable valve mechanism 600 converts the rotational motion of the electric motor 210, the speed reduction mechanism 220 that reduces the rotational speed of the motor 210, and the speed reduction mechanism 220 into the linear motion of the control shaft. A conversion mechanism 500 is provided. The motor 210 is provided with a rotation angle sensor 211 that detects the rotation angle of the motor 210.

  The speed reduction mechanism 220 includes a plurality of gears and the like. The input shaft of the speed reduction mechanism 220 is connected to the output shaft of the motor 210, and the output shaft of the speed reduction mechanism 220 is connected to a cam 530 provided in the conversion mechanism 500.

  The conversion mechanism 500 includes a holder 510 and a guide 520 that guides the movement of the holder 510, and the holder 510 moves forward and backward along the guide 520. A connection shaft 511 extending toward the control shaft 340 is attached to the holder 510, and an end portion of the connection shaft 511 is coupled to an end portion of the control shaft 340 on the connection shaft 511 side by a coupling member 400. .

  A cam 530 that is rotated by the output shaft of the speed reduction mechanism 220 is disposed in the holder 510. In addition, a roller 540 with which the cam surface of the cam 530 contacts is rotatably attached to the holder 510.

  When the cam 530 rotates, a holder 510 as a driven node that is a member to which the movement of the cam 530 is transmitted moves along the guide 520. As the holder 510 moves, the control shaft 340 is displaced in the axial direction, which is the direction in which the central axis of the control shaft 340 extends.

  A motor controller 150 that controls the driving of the motor 210 is connected to the motor 210. The rotation angle of the motor 210 is controlled in accordance with a drive signal from the motor control device 150. The motor control device 150 is connected to the engine control device 100 that controls the operating state of the internal combustion engine 1.

  The engine control device 100 receives an accelerator operation amount detected by an accelerator operation amount sensor, a crank angle detected by a crank angle sensor, and the like. Then, the engine control device 100 calculates the required intake air amount according to the engine operating state based on, for example, the engine rotational speed NE calculated from the crank angle and the accelerator operation amount ACCP, and the required intake air amount is obtained. The maximum lift amount of the intake valve 31 is calculated. The calculated maximum lift amount is set as the target lift amount VLp. When the target lift amount VLp is set in this way, the motor control device 150 calculates the rotational phase of the cam 530 corresponding to the target lift amount VLp, and the motor 210 has the calculated rotational phase. Control the rotation angle. Note that the drive of the motor 210 is duty-controlled by the motor control device 150, and the duty ratio given to the motor 210 when the motor 210 is rotated, that is, when the valve characteristics are changed, is a value close to the maximum value. Is set. As a result, the output torque of the motor 210 becomes a value close to the maximum value, and the control shaft 340 moves at a speed close to the maximum speed.

  Further, the motor control device 150 calculates the rotation phase of the cam 530 from the rotation angle of the motor 210 detected by the rotation angle sensor 211, and calculates the current value of the maximum lift amount VL from the calculated rotation phase. . Then, the motor control device 150 transmits the calculated current value of the maximum lift amount VL to the engine control device 100.

Next, the cam 530 that displaces the control shaft 340 will be described in detail.
As shown in FIG. 4, on the cam surface of the cam 530, the displacement of the control shaft 340 increases linearly as the cam diameter (radius from the cam rotation center to the cam surface) gradually increases in one direction. Sections (sections of the first rotation angle R1 to the second rotation angle R2 and the third rotation angle R3 to the fourth rotation angle R4 shown in FIG. 4) are provided. The cam surface of the cam 530 has a constant cam diameter and a constant displacement amount of the control shaft 340 (second rotation angle R2 to third rotation angle R3 shown in FIG. 4, fourth rotation). A section from the angle R4 to the fifth rotation angle R5 and a section before the first rotation angle R1 where the roller 540 contacts the reference circle 530b of the cam 530 are also provided.

  More specifically, the displacement amount of the control shaft 340 is maintained at “0” in the section where the rotation angle of the cam 530 is before the first rotation angle R1. Further, in a section where the rotation angle of the cam 530 is the second rotation angle R2 to the third rotation angle R3, the displacement amount of the control shaft 340 is maintained at “L1” which is a constant value. When the rotation angle of the cam 530 is between the fourth rotation angle R4 and the fifth rotation angle R5, the displacement amount of the control shaft 340 is a constant value and is maintained at “L2” which is larger than the above “L1”. . The section in which the displacement amount of the control shaft 340 is constant in this way is hereinafter referred to as “holding area”.

Since the cam surface of the cam 530 has the above-described cam profile, the maximum lift amount VL of the intake valve 31 changes as shown in FIG. 5 while the cam 530 makes one rotation.
As shown in FIG. 5, as the rotation angle of the motor 210 increases, the rotation angle of the cam 530 gradually increases. In the section before the first rotation angle R1 where the roller 540 is in contact with the reference circle 530b of the cam 530, the displacement amount of the control shaft 340 is “0”, and the maximum lift amount VL at this time is the first lift amount VL. One lift amount VL1 is maintained. The first lift amount VL1 is the minimum value of the maximum lift amount VL. In the process in which the rotation angle of the cam 530 changes from the first rotation angle R1 to the second rotation angle R2, the displacement amount of the control shaft 340 gradually increases, so the maximum lift amount VL is the first lift amount VL1. It gradually grows from.

  In the section where the rotation angle of the cam 530 is the second rotation angle R2 to the third rotation angle R3, the displacement amount of the control shaft 340 is maintained at a constant “L1”, so the maximum lift amount VL at this time is the first lift amount VL. The second lift amount VL2 is held larger than the lift amount VL1. In the process in which the rotation angle of the cam 530 changes from the third rotation angle R3 to the fourth rotation angle R4, the displacement amount of the control shaft 340 gradually increases, so the maximum lift amount VL is equal to the second lift amount VL2. It gradually grows from.

  In the section where the rotation angle of the cam 530 is the fourth rotation angle R4 to the fifth rotation angle R5, the displacement amount of the control shaft 340 is maintained at “L2” which is larger than the above “L1”. VL is held at a third lift amount VL3 that is larger than the second lift amount VL2. The third lift amount VL3 is the maximum value of the maximum lift amount VL.

  Here, since the reaction force from the valve spring 24 acts on the output portion 320 of the variable mechanism portion 300, a force for reducing the relative phase difference between the input arm 311 and the output arm 321 is applied. Therefore, an axial force acts on the slider gear 350 and the control shaft 340 in the direction in which the maximum lift amount VL of the intake valve 31 decreases (the direction of the arrow Lo shown in FIGS. 2 and 3). When this axial force acts on the cam surface of the section where the displacement amount of the control shaft 340 is changed in the cam 530, a component force is generated from the axial force, and the cam 530 has a maximum lift amount VL due to the component force. Rotational torque acting in the direction of decreasing works. For this reason, if the maximum lift amount VL is to be maintained within a section in which the displacement amount of the control shaft 340 changes, it is necessary to generate a force against the rotational torque from the motor 210, and supply a holding current to the motor 210. There is a need to.

  On the other hand, when the axial force acts on the cam surface of the holding region described above in the cam 530, that is, the axial force acts on the cam surface in a section where the cam diameter is constant and the displacement of the control shaft 340 is constant. Sometimes, even if such an axial force is applied, the generation of a component force from that axial force is suppressed. Therefore, the generation of the rotational torque due to the axial force is suppressed. Therefore, when the maximum lift amount VL is held in a section where the displacement amount of the control shaft 340 is constant, the holding current supplied to the motor 210 can be reduced.

  Accordingly, in the variable valve mechanism 600, the first lift amount VL1, the second lift amount VL2, and the third lift amount VL3 are selected as the maximum lift amount VL of the intake valve 31 according to the engine operating state. To do. The maximum lift amount VL of the intake valve 31 is changed in three stages by holding the selected maximum lift amount. Thus, the variable valve mechanism 600 is used as a multi-stage variable variable valve mechanism that changes the valve characteristics in multiple stages.

  By the way, if the valve characteristics of the intake valve 31 change between the start of fuel injection in the internal combustion engine 1 and the closing of the intake valve 31, the intake air amount changes from the time of fuel injection, so the air-fuel ratio becomes smaller. It will get worse. Therefore, the engine control apparatus 100 estimates the intake air amount by an air model using various parameters, and when estimating the intake air amount, the estimated value of the valve characteristic is one of the various parameters described above. Is used.

  More specifically, as shown in FIG. 6, when the engine operating state changes at time t1 and the target lift amount VLp corresponding to the engine operating state changes accordingly, the engine control device 100 immediately sets the target lift amount. Instead of changing VLp, the target lift amount VLp is changed after a predetermined delay time DL has elapsed (time t2). By changing the target lift amount VLp at time t2, the actual maximum lift amount VL changes toward the changed target lift amount VLp.

  On the other hand, when the engine operating state changes at time t1 and thereby the target lift amount VLp corresponding to the engine operating state changes, it is assumed that the engine control device 100 immediately changes the target lift amount VLp at time t1. The virtual target amount VLVp corresponding to the change in the target lift amount VLp at the time is changed from the target lift amount VLp before the change to the target lift amount VLp after the change.

  The engine control apparatus 100 calculates a virtual lift amount VLV that estimates a change in the maximum lift amount VL when it is assumed that the target lift amount VLp is immediately changed at time t1. That is, the estimated value of the maximum lift amount VL during the change of the valve characteristic when it is assumed that the valve characteristic has been changed is calculated as the virtual lift amount VLV. The engine control apparatus 100 uses the virtual lift amount VLV when estimating the intake air amount by the air model, and sets the fuel injection amount according to the intake air amount estimated based on the virtual lift amount VLV and the like. I am doing so.

  In this way, when the valve characteristic is changed due to the change in the engine operating state, the engine control apparatus 100 delays the change of the actual valve characteristic (maximum lift amount VL) by the delay time DL. On the other hand, the engine control apparatus 100 grasps the change in the valve characteristic in advance prior to the change in the valve characteristic, and the intake air amount based on the change in the valve characteristic grasped in advance (change in the virtual lift amount VLV). Thus, the deterioration of the air-fuel ratio as described above is suppressed.

  In estimating the intake air amount using such an air model, the estimation accuracy of the virtual lift amount VLV affects the estimation accuracy of the intake air amount. Therefore, the engine control apparatus 100 calculates the virtual lift amount VLV as follows, thereby accurately calculating the virtual lift amount VLV during the change of the maximum lift amount VL when it is assumed that the target lift amount VLp has been changed. I try to make a good estimate.

Hereinafter, calculation of the virtual lift amount VLV will be described with reference to FIGS.
First, a processing procedure for setting an initial value of the virtual lift amount VLV will be described with reference to FIG. This process is executed by the engine control device 100 at predetermined intervals.

  As shown in FIG. 7, when this process is started, it is first determined whether or not the engine has been started (S100). When the engine is not started, that is, when the engine is not started (S100: NO), the maximum lift amount VL does not change, so the current maximum lift amount VL is set as the virtual lift amount VLV (S300). This process is temporarily terminated.

  On the other hand, when it is after the engine is started (S100: YES), the maximum lift amount VL changes variously. Therefore, the virtual lift amount VLV calculation process is executed (S200), and this process is temporarily terminated.

In this way, the engine control apparatus 100 sets the maximum lift amount VL before starting the engine as the initial value of the virtual lift amount VLV.
Next, the process of step S200, that is, the calculation process of the virtual lift amount VLV executed after the engine is started will be described with reference to FIGS. This process is also executed at predetermined intervals by the engine control apparatus 100.

As shown in FIG. 8, when this process is started, it is first determined whether or not the current virtual lift amount VLV is a value that satisfies the following equation (1) (S210).

VLVp−H ≦ VLV ≦ VLVp + H (1)
VLVp: Virtual target amount
VLV: Virtual lift amount
H: Constant

The constant H is appropriately set to such a degree of deviation that it can be determined that the virtual lift amount VLV and the virtual target amount VLVp substantially match.

  When the valve characteristic is not changed, that is, when the maximum lift amount VL is held in any one of the first lift amount VL1, the second lift amount VL2, and the third lift amount VL3 described above, The lift amount VLV matches the virtual target amount VLVp. Accordingly, in this case, an affirmative determination is made in step S210 (S210: YES), the current virtual target amount VLVp is set to the virtual lift amount VLV (S280), and this process is temporarily ended. By the process of step S280 or the process of step S300 shown in FIG. 7, a value that is the valve characteristic before changing the valve characteristic and becomes the reference value of the virtual lift amount VLV is set.

  On the other hand, when the target lift amount VLp corresponding to the engine operating state changes, the virtual target amount VLVp is changed. When the virtual target amount VLVp is changed in this way, the virtual lift amount VLV thereafter changes, and the above equation (1) is satisfied until the virtual lift amount VLV substantially coincides with the virtual target amount VLVp. Not. Accordingly, in this case, a negative determination is made in step S210. And in order to estimate the valve characteristic in the middle of the change of the valve characteristic when it assumes that the valve characteristic was changed, the process after step S220 is performed sequentially.

  In step S220, it is determined whether or not the virtual target amount VLVp exceeds the virtual lift amount VLV. In step S220, an affirmative determination is made, for example, when the virtual target amount VLVp is changed to the increasing side due to a change in the target lift amount VLp corresponding to the engine operating state.

  If an affirmative determination is made in step S220, then an increase amount A for increasing the virtual lift amount VLV is calculated (S230). The increase amount A is an estimated change speed of the valve characteristic while the valve characteristic is being changed so as to increase the virtual lift amount VLV per unit time, that is, the maximum lift amount. The increase amount A is set based on the following equation (2).

Increase amount A = Basic increase amount Ab × oil coefficient K1 × motor coefficient K2 (2)

In step S260 described later, a reduction amount B for reducing the virtual lift amount VLV is calculated. This decrease amount B is an estimated change speed of the valve characteristic while the valve characteristic is being changed so that the decrease amount of the virtual lift amount VLV per unit time, that is, the maximum lift amount becomes small. The decrease amount B is set based on the following equation (3).

Reduction amount B = Basic reduction amount Bb × oil coefficient K1 × motor coefficient K2 (3)

The basic increase amount Ab and the basic decrease amount Bb are values described below.

  First, as described above, the control shaft 340 has one axial direction (the direction in which the maximum lift amount VL decreases (FIGS. 2 and 3) due to the reaction force of the valve spring 24 that urges the intake valve 31. Axial force acting on the arrow Lo direction)) shown in FIG. When the acting direction of the axial force and the drive direction of the control shaft 340 driven by the motor 210 are the same, that is, when the maximum lift amount VL is reduced, the change speed of the valve characteristic is increased. On the other hand, when the acting direction of the axial force is opposite to the driving direction of the control shaft 340 driven by the motor 210, that is, when the maximum lift amount VL is increased, the changing speed of the valve characteristic is slow.

As described above, the change speed of the valve characteristic changes under the influence of the axial force, but the magnitude of the axial force tends to change depending on the engine speed.
FIG. 9 shows the relationship between the engine speed NE and the axial force. As shown in FIG. 9, the axial force temporarily decreases as the engine speed NE increases. Then, the axial force gradually increases as the engine rotational speed NE increases from when the engine rotational speed NE exceeds the middle rotational speed region. Thus, the axial force increases in the low rotation speed region and the high rotation speed region, and the axial force decreases in the medium rotation speed region. When the maximum lift amount VL is increased, the acting direction of the axial force and the driving direction of the control shaft 340 driven by the motor 210 are reversed, so that the change speed of the valve characteristic is slower as the axial force is larger. Become. On the contrary, when the maximum lift amount VL is reduced, the acting direction of the axial force is the same as the driving direction of the control shaft 340 driven by the motor 210. Therefore, the change rate of the valve characteristic is increased as the axial force is increased. Get faster.

  In consideration of the influence of the axial force on the change speed of the valve characteristics, in the present embodiment, the basic value of the increase amount A corresponding to the estimated change speed of the virtual lift amount VLV when the maximum lift amount VL is increased. A certain basic increase amount Ab is variably set based on the engine speed NE. Further, with respect to the reduction amount B corresponding to the estimated change speed of the virtual lift amount VLV when the maximum lift amount VL is reduced, the basic reduction amount Bb, which is the basic value, is variably set based on the engine speed NE. ing. The basic increase amount Ab and the basic decrease amount Bb are both positive values.

  As shown in FIG. 10, the basic increase amount Ab is increased as the engine speed NE increases, and the basic increase amount Ab reaches a maximum value in the intermediate speed region. Then, in the speed region where the basic increase amount Ab exceeds the engine rotation speed NE where the maximum value is obtained, the basic increase amount Ab is decreased as the engine rotation speed NE increases.

  As shown in FIG. 11, the basic reduction amount Bb is reduced as the engine speed NE increases, and the basic reduction amount Bb becomes a minimum value in the intermediate speed region. In a speed region where the basic reduction amount Bb exceeds the engine rotation speed NE where the minimum value is obtained, the basic reduction amount Bb is increased as the engine rotation speed NE increases.

  As shown in FIG. 12, the oil coefficient K1 is a value that is variably set within the range of “0 <K1 ≦ 1” based on the oil temperature, and is gradually increased as the oil temperature increases. When the oil temperature exceeds a predetermined temperature, the oil coefficient K1 is fixed to “1”. Note that the oil coefficient K1 may be gradually increased as the oil temperature increases without providing a temperature region in which the oil coefficient K1 is fixed to “1”.

  As shown in FIG. 13, the motor coefficient K2 is also a value that is variably set within the range of “0 <K1 ≦ 1” based on the oil temperature. It is fixed at “1” in a low oil temperature region where there is no influence. In the region where the oil temperature is higher than the temperature region where the motor coefficient K2 is fixed to “1”, the motor coefficient K2 is gradually reduced as the oil temperature increases. Note that the motor coefficient K2 may be gradually decreased as the oil temperature rises without providing a temperature region in which the motor coefficient K2 is fixed to “1”.

  When the increase amount A is calculated in step S230 in this way, in step S240, the virtual lift amount VLV is increased, and this process is temporarily terminated. In the increase process in step S240, the increase amount A calculated in step S230 is added to the virtual lift amount VLV calculated in the previous execution cycle of this process, and thereby the virtual lift amount VLV in the current execution cycle. Is calculated.

  As shown in FIG. 14, when the calculation process of the virtual lift amount VLV is executed and the process of step S240 is performed for each execution cycle, the process of step S280 shown in FIG. 8 or the previous FIG. The virtual lift amount VLV set by the processing of step S300 shown is used as a reference value of the virtual lift amount VLV before the valve characteristic change, and the virtual lift amount VLV is increased by an increase amount A every execution cycle. As described above, in step S240, the virtual lift amount VLV that is increased by the increase amount A from the reference value of the virtual lift amount VLV is calculated, so that it is assumed that the maximum lift amount VL is increased. The maximum lift amount VL is estimated as the virtual lift amount VLV.

  On the other hand, when a negative determination is made in step S220, it is determined whether or not the virtual target amount VLVp is smaller than the virtual lift amount VLV (S250). In step S250, an affirmative determination is made, for example, when the virtual target amount VLVp is changed to a decreasing side due to a change in the target lift amount VLp corresponding to the engine operating state.

Then, when a negative determination is made in step S250, this process is temporarily terminated.
On the other hand, when an affirmative determination is made in step S250, the above-described reduction amount B is calculated in order to increase the virtual lift amount VLV (S260). The oil coefficient K1 and the motor coefficient K2 when calculating the decrease amount B are calculated in the same manner as the oil coefficient K1 and the motor coefficient K2 when calculating the increase amount A.

  When the reduction amount B is calculated in step S260 in this way, in step S270, the virtual lift amount VLV reduction processing is performed, and this processing is once ended. In the decrease process in step S270, the decrease amount B calculated in step S260 is subtracted from the virtual lift amount VLV calculated in the previous execution cycle of this process, and thereby the virtual lift amount VLV in the current execution cycle is subtracted. Is calculated.

  When the calculation process of the virtual lift amount VLV is executed and the process of step S270 is performed for each execution cycle, the process of step S280 shown in FIG. 8 or the process of step S300 shown in FIG. Using the set virtual lift amount VLV as a reference value, the virtual lift amount VLV is decreased by a decrease amount B every execution cycle. As described above, in step S270, the virtual lift amount VLV that is decreased by the decrease amount B from the reference value of the virtual lift amount VLV is calculated, so that the maximum lift amount VL is assumed to be small, and the valve characteristics are changed in the middle. The maximum lift amount VL is estimated as the virtual lift amount VLV.

Next, the operation of this embodiment will be described.
When the maximum lift amount of the intake valve 31 is increased, the change speed of the valve characteristic is slowed by the influence of the axial force. Then, as shown in FIG. 9, the axial force once decreases as the engine rotational speed NE increases, and the engine rotational speed NE increases after the engine rotational speed NE exceeds the middle rotational speed region. The axial force tends to increase gradually as it rises. Considering these points, the basic increase amount Ab is variably set in the manner shown in FIG. That is, the basic increase amount Ab is increased as the engine speed NE increases, and the basic increase amount Ab becomes a maximum value in the intermediate speed region. Then, in the speed region where the basic increase amount Ab exceeds the engine rotation speed NE where the maximum value is obtained, the basic increase amount Ab is decreased as the engine rotation speed NE increases.

  On the other hand, when the maximum lift amount of the intake valve 31 is reduced, the change speed of the valve characteristics increases due to the influence of the axial force. As described above, the axial force once decreases as the engine rotational speed NE increases, and from the point where the engine rotational speed NE exceeds the middle rotational speed region, the shaft increases as the engine rotational speed NE increases. The power tends to increase gradually. Considering these points, the basic reduction amount Bb is variably set in the manner shown in FIG. That is, the basic reduction amount Bb is reduced as the engine speed NE increases, and the basic reduction amount Bb becomes a minimum value in the intermediate speed region. In a speed region where the basic reduction amount Bb exceeds the engine rotation speed NE where the minimum value is obtained, the basic reduction amount Bb is increased as the engine rotation speed NE increases.

  As described above, the change speed of the valve characteristic changes under the influence of the axial force, but the magnitude of the axial force tends to change depending on the engine rotational speed NE. Therefore, the basic increase amount Ab and the basic decrease amount Bb, which are the basic values of the estimated change speed of the valve characteristics, are variably set based on the engine speed NE. That is, the basic increase amount Ab and the basic decrease amount Bb are variably set according to the magnitude of the axial force acting on the control shaft 340, which is a force that changes according to the engine speed NE. Thereby, the estimated change speed (increase amount A or decrease amount B) can be set with high accuracy in consideration of the influence of the axial force. Therefore, in the multistage variable type variable valve mechanism 600, the virtual lift amount VLV during the change of the valve characteristic when it is assumed that the valve characteristic has been changed can be accurately estimated.

  As described above, the estimated change speed of the valve characteristic has a strong correlation with the operation speed of the control shaft 340. The operating speed of the control shaft 340 tends to change under the influence of the engine temperature. Therefore, in the present embodiment, the estimated change speed is variably set in consideration of not only the engine rotational speed NE related to the magnitude of the axial force but also the engine temperature, that is, the increase amount A or the decrease is considered in consideration of the engine temperature. In order to variably set the amount B, the oil coefficient K1 corrects the basic increase amount Ab and the basic decrease amount Bb by the motor coefficient K2. Therefore, the accuracy of the estimated change speed is increased.

  The engine temperature can be substituted by an oil temperature that is the temperature of the lubricating oil of the engine or a cooling water temperature that is the temperature of the cooling water of the engine, in addition to directly detecting the engine temperature by a sensor or the like. Therefore, in the present embodiment, the oil temperature is used as a substitute value for the engine temperature, but other parameters may be used.

  Further, the lower the viscosity of the lubricating oil as the engine temperature increases, the smaller the friction when the control shaft 340 operates, so the operating speed of the control shaft 340 increases and the rate of change of the valve characteristics also increases. Therefore, as the viscosity of the lubricating oil decreases as the engine temperature increases, the estimated change speed of the virtual lift amount VLV is set to a higher speed, that is, as the lubricating oil viscosity decreases, the increasing amount A or the decreasing amount. The oil coefficient K1 is set as a value for correcting the basic increase amount Ab and the basic decrease amount Bb so that B increases. Therefore, the accuracy of the estimated change speed of the valve characteristics such as the increase amount A and the decrease amount B is increased.

  Further, when the ambient temperature of the motor 210 increases with the increase in the engine temperature, the electric resistance in the motor 210 increases, so that the current flowing in the motor 210 decreases and the output torque of the motor 210 decreases. When the output torque of the motor 210 is reduced in this way, the operating speed of the control shaft 340 is reduced and the changing speed of the valve characteristics is also reduced. Therefore, as the output torque of the motor 210 decreases as the engine temperature increases, the estimated change speed of the virtual lift amount VLV is set to a slower speed, that is, as the output torque of the motor 210 decreases, the increase amount A or The motor coefficient K2 is set as a value for correcting the basic increase amount Ab and the basic decrease amount Bb so that the decrease amount B becomes small. Therefore, this also increases the accuracy of the estimated change speed of the valve characteristics such as the increase amount A and the decrease amount B.

  Further, based on the virtual lift amount VLV in the middle of changing the valve characteristic when it is assumed that the valve characteristic has been changed, the intake air amount in the middle of changing the valve characteristic is estimated by the air model. In the present embodiment, since the virtual lift amount VLV is accurately estimated as described above, it is possible to accurately estimate the intake air amount during the change of the valve characteristic when it is assumed that the valve characteristic has been changed. .

As described above, according to the present embodiment, the following effects can be obtained.
(1) The basic values (the basic increase amount Ab and the basic decrease amount Bb) of the increase amount A and the decrease amount B, which are estimated change speeds of the maximum lift amount VL, are variably set based on the engine speed NE. Therefore, the estimated change speed can be set with high accuracy in consideration of the influence of the axial force acting on the control shaft 340. Therefore, in the internal combustion engine 1 including the multistage variable variable valve mechanism 600, it is possible to accurately estimate the virtual lift amount VLV in the course of changing the valve characteristic when it is assumed that the valve characteristic has been changed.

  (2) The increase amount A and the decrease amount B, which are estimated change speeds of the maximum lift amount VL, are variably set based on the engine speed NE and the engine temperature (oil temperature). Therefore, the accuracy of the estimated change speed of the maximum lift amount VL can be increased.

  (3) The increase amount A and the decrease amount B, which are the estimated change speeds of the maximum lift amount VL, are set to higher speeds as the viscosity of the lubricating oil becomes lower as the engine temperature (oil temperature) increases. . Therefore, the accuracy of the estimated change speed can be increased.

  (4) The increase amount A and the decrease amount B, which are the estimated change speeds of the maximum lift amount VL, are set to slower speeds as the output torque of the motor 210 becomes lower as the engine temperature (oil temperature) increases. Yes. Therefore, this also increases the accuracy of the estimated change speed.

  (5) The intake air amount during the change of the valve characteristics is estimated based on the virtual lift amount VLV using an air model. Accordingly, it is possible to accurately estimate the intake air amount during the change of the valve characteristic when it is assumed that the valve characteristic has been changed.

In addition, the said embodiment can also be changed and implemented as follows.
As the estimated change speed of the valve characteristic, the increase amount A that is the increase amount of the maximum lift amount VL per unit time and the decrease amount B that is the decrease amount of the maximum lift amount VL per unit time are calculated. However, the estimated change speed of the valve characteristic may be calculated in another manner. For example, the estimated change speed of the valve characteristic may be calculated using a model formula. In this case, the estimated change speed of the valve characteristic is set by variably setting various coefficients of the model formula based on the engine speed. Can be variably set based on the engine speed.

  -The above-mentioned axial force, the friction of the control shaft 340, the output torque of the motor 210, etc. have individual differences for each variable valve mechanism 600. Therefore, the estimated change speed may be corrected according to the difference between the actual change speed of the valve characteristic and the estimated change speed during the change of the valve characteristic. In this case, the individual difference for each variable valve mechanism 600 is compensated, and the accuracy of the estimated change speed of the valve characteristics in each variable valve mechanism 600 can be increased.

An example of the processing procedure in this modification is shown in FIG. The series of processing shown in FIG. 15 is executed by the engine control device 100 at predetermined intervals.
As shown in FIG. 15, when this process is started, it is first determined whether or not the maximum lift amount VL is increasing (S400). When the maximum lift amount VL is increasing (S400: YES), the increasing side change speed AS of the maximum lift amount VL is measured (S410). The increase side change speed AS is a change speed of the actual maximum lift amount VL when the maximum lift amount VL is increased, and is measured based on a detection value of the rotation angle sensor 211.

Then, the basic increase amount Ab, the oil coefficient K1, or the motor coefficient K2 is corrected based on the increase side change speed AS (S420), and this process is temporarily terminated.
In step S420, the basic increase amount Ab, the oil coefficient K1, and the motor coefficient K2 are corrected so that the difference between the increase side change speed AS, which is the actual change speed of the valve characteristics, and the estimated change speed of the valve characteristics is reduced. . For example, the actual value of the increase amount A is obtained from the increase side change speed AS. Then, the deviation between the increase amount A calculated from the above equation (2) and the actual value of the increase amount A is calculated, and the basic increase amount Ab, the oil coefficient K1, and the motor coefficient K2 are corrected so that the deviation becomes smaller. To do. For simplicity, the basic increase amount Ab may be corrected so that the deviation between the increase amount A calculated from the above equation (2) and the actually measured value of the increase amount A is reduced. More simply, the correction for directly correcting the increase amount A calculated from the above equation (2) based on the deviation between the increase amount A calculated from the above equation (2) and the actual value of the increase amount A. A value may be calculated. The increase side change speed AS also changes depending on the difference in axial force due to the difference in the engine speed NE, the viscosity of the lubricating oil, and the output torque of the motor 210. Therefore, it is desirable to measure the increasing side change speed AS for each of various engine rotational speeds NE and engine temperatures, and calculate the correction coefficient for each engine rotational speed NE and engine temperature.

  On the other hand, when a negative determination is made in step S400, it is determined whether or not the maximum lift amount VL is decreasing (S430). When the maximum lift amount VL is not decreased (S400: NO), this process is temporarily terminated.

  On the other hand, when the maximum lift amount VL is decreasing (S430: YES), the decreasing side change speed BS of the maximum lift amount VL is measured (S440). The decrease side change speed BS is a change speed of the actual maximum lift amount VL when the maximum lift amount VL is reduced, and is measured based on a detection value of the rotation angle sensor 211.

Then, the basic reduction amount Bb, the oil coefficient K1, or the motor coefficient K2 is corrected based on the decreasing side change speed BS (S450), and this process is temporarily ended.
In step S450, the basic reduction amount Bb, the oil coefficient K1, and the motor coefficient K2 are corrected so that the difference between the decrease side change speed BS, which is the actual change speed of the valve characteristics, and the estimated change speed of the valve characteristics becomes small. . For example, an actual measurement value of the decrease amount B is obtained from the decrease side change speed BS. Then, the deviation between the reduction amount B calculated from the above equation (3) and the measured value of the reduction amount B is calculated, and the basic reduction amount Bb, the oil coefficient K1, and the motor coefficient K2 are corrected so that the deviation becomes small. To do. For simplicity, the basic reduction amount Bb may be corrected so that the deviation between the reduction amount B calculated from the above equation (3) and the actual measurement value of the reduction amount B may be reduced. More simply, the correction for directly correcting the decrease amount B calculated from the above equation (3) based on the deviation between the decrease amount B calculated from the above equation (3) and the actual value of the decrease amount B. A value may be calculated. Note that the decrease side change speed BS also changes depending on the difference in axial force due to the difference in the engine speed NE, the viscosity of the lubricating oil, and the output torque of the motor 210. Therefore, it is desirable to measure the decrease side change speed BS for each of various engine rotational speeds NE and engine temperatures, and calculate the correction coefficient for each engine rotational speed NE and engine temperature.

  Further, the basic increase amount Ab, the basic decrease amount Bb, the oil coefficient K1, and the motor coefficient K2 shown in FIGS. 10 to 13 are set as initial values. Then, the increase side change speed AS and the decrease side change speed BS are measured for each of various engine rotational speeds NE and engine temperatures, and the basic increase amount Ab and the basic decrease amount according to the actual change speed of the valve characteristics are measured from the measurement results. Bb, oil coefficient K1, and motor coefficient K2 are calculated. Then, the calculated initial values of the basic increase amount Ab, the basic decrease amount Bb, the oil coefficient K1, and the motor coefficient K2 shown in FIGS. 10 to 13 may be overwritten. .

  When the operating direction of the control shaft 340 is opposite to the direction in which the axial force is applied, that is, when the control shaft 340 is moved so that the maximum lift amount VL is increased, the valve is operated when the axial force is very large. If the characteristics are changed greatly, the control shaft 340 must be driven greatly against a large axial force. Therefore, an excessive load may be applied to the control shaft 340, the motor 210, and the like. Therefore, when the operating direction of the control shaft is opposite to the operating direction of the axial force and the axial force acting on the control shaft 340 is larger than a predetermined value, the valve characteristic is larger than when the axial force is less than the predetermined value. The amount of change may be reduced. In this case, it is possible to suppress an excessive load from being applied to the control shaft 340, the motor 210, and the like.

  For example, when the engine rotation speed NE is lower than a predetermined low rotation determination value and the axial force becomes larger than a predetermined value, or when the engine rotation speed NE is higher than a predetermined high rotation determination value, the axial force is a predetermined value. When the maximum lift amount VL is larger than the predetermined amount, the change amount when the maximum lift amount VL is increased may be suppressed as compared with the case where the axial force is equal to or less than a predetermined value.

  FIG. 16 shows an example of this modification. As shown in FIG. 16, for example, when the maximum lift amount VL is increased from the second lift amount VL2 toward the third lift amount VL3, when the axial force acting on the control shaft 340 is larger than a predetermined value, engine operation is performed. The target lift amount VLp set based on the state is changed stepwise from the second lift amount VL2 toward the third lift amount VL3. As a result, the actual maximum lift amount VL is changed stepwise from the second lift amount VL2 toward the third lift amount VL3, so that the maximum lift amount VL is changed compared to when the axial force is equal to or less than a predetermined value. The amount can be reduced. Incidentally, when the actual maximum lift amount VL is changed stepwise from the second lift amount VL2 to the third lift amount VL3 in this way, the cam surface of the cam 530 different from the holding region, that is, the maximum lift amount. A cam surface on which VL gradually changes may be used, and a holding current may be supplied to the motor 210 to temporarily hold the maximum lift amount VL. Further, when the target lift amount VLp is changed stepwise in this way, it is desirable that the virtual target amount VLVp is similarly changed stepwise in accordance with such a change mode of the target lift amount VLp.

  The correction of the estimated change speed by the oil coefficient K1 can be changed as appropriate. In short, the estimated change speed of the valve characteristic when the valve characteristic is changed may be set to a higher speed as the viscosity of the lubricating oil decreases as the engine temperature increases. Further, the correction of the estimated change speed by the motor coefficient K2 can be changed as appropriate. In short, the estimated change speed of the valve characteristic when the valve characteristic is changed may be set to a slower speed as the output torque of the motor 210 decreases as the engine temperature increases.

  The correction of the estimated change speed by the oil coefficient K1 may be omitted by deleting the oil coefficient K1 from the above formulas (2) and (3). Further, the motor coefficient K2 may be deleted from the above equations (2) and (3), and the correction of the estimated change speed by the motor coefficient K2 may be omitted.

The series of processing shown in FIGS. 7 and 8 may be performed by the motor control device 150 instead of the engine control device 100.
The virtual lift amount VLV may be used other than the estimation of the intake air amount.

  In the above embodiment, the estimated value of the maximum lift amount VL during the change of the valve characteristic when it is assumed that the valve characteristic has been changed is calculated as the virtual lift amount VLV. That is, the virtual lift amount VLV is a value when it is assumed that the valve characteristic is changed. In addition, the virtual lift amount VLV may be calculated as an estimated value of the maximum lift amount VL during the change of the valve characteristic when the valve characteristic is actually changed. That is, the virtual lift amount VLV may be used as an estimated value of the maximum lift amount VL when the valve characteristic is actually changed. In this case, for example, a sensor for detecting the maximum lift amount VL or the like can be omitted, or such a sensor can be replaced with one having a simpler structure.

  When the valve characteristic is changed by the variable mechanism unit 300, the maximum lift amount VL of the intake valve 31 and the valve opening period INCAM change synchronously. Therefore, in the above embodiment, various control values related to the maximum lift amount VL are calculated, but various control values related to the valve opening period INCAM (for example, the target value of the valve opening period INCAM, the valve opening period INCAM, and the like). Or the like may be calculated.

  The maximum lift amount of the intake valve 31 changed by the variable valve mechanism 600 was three stages. In addition, a variable valve mechanism that changes the maximum lift amount of the intake valve 31 to two stages or changes to four stages or more may be used.

The shape of the cam 530 is an example, and other shapes may be used as long as the cam can move the control shaft 340 in the axial direction.
The structure of the variable valve mechanism 600 is an example, and may be a variable valve mechanism that changes the valve characteristics stepwise with another structure. For example, when a direct-acting valve system is provided, the valve characteristics can be changed stepwise by providing a variable valve mechanism that changes the operation amount of a valve lifter operated by a cam in multiple stages. In addition, when a rocker arm type valve system is provided, the valve characteristics can be changed in stages by providing a variable valve mechanism that changes the sinking amount of the lash adjuster that supports the rocker arm in multiple stages. . Further, when a rocker arm type valve system is provided, the valve characteristics can be changed in stages by providing a variable valve mechanism that changes the shape of the rocker arm in multiple stages.

  The variable mechanism unit 300 is a mechanism that can change the maximum lift amount and the valve opening period of the intake valve 31. In addition, a mechanism that can change only the maximum lift amount or a mechanism that can change only the valve opening period may be used. Further, a variable mechanism that changes valve characteristics (for example, valve opening timing, valve closing timing, etc.) different from the maximum lift amount and the valve opening period may be used.

  The variable mechanism section 300 is provided in the valve operating system of the intake valve 31, but may be provided in the valve operating system of the exhaust valve 41.

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 10 ... Cylinder block, 11 ... Cylinder, 12 ... Piston, 13 ... Combustion chamber, 20 ... Cylinder head, 21 ... Intake port, 22 ... Exhaust port, 24 ... Valve spring, 25 ... Rush adjuster, 26 ... Rocker arm, 26a ... roller, 30 ... intake passage, 31 ... intake valve, 32 ... intake camshaft, 32a ... intake cam, 33 ... throttle valve, 40 ... exhaust passage, 41 ... exhaust valve, 42 ... exhaust camshaft, 42a ... Exhaust cam 50 ... Spring 100 ... Engine control device 150 ... Motor control device 210 ... Motor 211 ... Rotation angle sensor 220 ... Deceleration mechanism 300 ... Variable mechanism unit 310 ... Input unit 311 ... Input Arm, 311a ... roller, 312 ... helical spline, 313 ... projection, 314 ... housing, DESCRIPTION OF SYMBOLS 20 ... Output part, 321 ... Output arm, 322 ... Helical spline, 323 ... Housing, 330 ... Support pipe, 340 ... Control shaft, 350 ... Slider gear, 351 ... Helical spline, 352 ... Helical spline, 400 ... Connecting member, 500 ... Conversion mechanism, 510 ... holder, 511 ... connection shaft, 520 ... guide, 530 ... cam, 530b ... reference circle, 540 ... roller, 600 ... variable valve mechanism.

Claims (6)

A variable mechanism section that changes the valve characteristics of the engine valve, a control shaft that operates the variable mechanism section, and an electric motor that drives the control shaft, and any one of a plurality of predetermined valve characteristics A control device for an internal combustion engine comprising a multistage variable type variable valve mechanism that changes a valve characteristic in multiple stages by selecting a valve characteristic,
Estimate the estimated change speed of the valve characteristics during the change of the valve characteristics based on the engine speed,
Based on the valve characteristic before changing the valve characteristic and the estimated change velocity and estimated the valve characteristics in the middle changes the valve characteristic,
Find the difference between the actual valve characteristic change rate and the estimated change rate,
The numerical value of the arithmetic expression used when estimating the estimated change rate is corrected so that the difference becomes small,
With a variable valve mechanism , when the estimated change speed is newly estimated after correcting the numerical value of the arithmetic expression, the estimated change speed is estimated using the arithmetic expression after correcting the numerical value. Control device for internal combustion engine. The estimated rate of change, controlling a variable valve mechanism with an internal combustion engine according to claim 1 which is estimated in accordance with the magnitude of the axial force acting on the control shaft a force which varies in accordance with the engine rotational speed apparatus. The control device for an internal combustion engine with a variable valve mechanism according to claim 1, wherein the estimated change speed is estimated based on an engine rotation speed and an engine temperature. The control device for an internal combustion engine with a variable valve mechanism according to claim 3, wherein the estimated change speed is estimated to be faster as the viscosity of the lubricating oil becomes lower as the engine temperature increases. The control apparatus for an internal combustion engine with a variable valve mechanism according to claim 3, wherein the estimated change speed is estimated to be slower as the output torque of the electric motor becomes lower as the engine temperature increases. When the operating direction of the control shaft is opposite to the operating direction of the axial force acting on the control shaft, when the axial force is greater than a predetermined value, the valve is compared with when the axial force is less than the predetermined value. Reduce the amount of characteristic change
The control device for an internal combustion engine with a variable valve mechanism according to any one of claims 1 to 5 .