JP5874614B2 - Variable valve operating device for internal combustion engine - Google Patents

Description

  The present invention relates to a variable valve gear provided in an internal combustion engine.

  2. Description of the Related Art A variable valve operating device that changes a maximum lift amount of an engine valve according to an engine operating state is known. For example, a variable valve operating device described in Patent Document 1 includes a control shaft, a cam that changes the position of the control shaft in the axial direction in which the central axis of the control shaft extends, a motor that rotationally drives the cam, A control device for controlling the rotation drive is provided. On the cam surface of the cam, there is a holding section where the displacement amount of the control shaft is constant and the maximum lift amount is held at a constant value, and a changing section where the maximum lift amount changes as the displacement amount of the control shaft changes. Is formed. In this variable valve operating apparatus, the maximum lift amount is changed by changing the position of the control shaft using the cam surface changing section. Further, the maximum lift amount is held at a constant value by holding the position of the control shaft at a constant value using the holding section of the cam surface.

JP 2004-339951 A

  By the way, an axial force (hereinafter referred to as an axial force) is applied to the control shaft due to a reaction force of a valve spring that biases the engine valve. When this axial force acts on the cam surface in the change section, rotational torque acts on the cam in a direction in which the maximum lift amount decreases due to the component force generated from the axial force.

  When the maximum lift amount of the engine valve is increased, if such rotational torque is applied, the cam rotation direction and the rotational torque operation direction are reversed, so the controllability when changing the maximum lift amount is reduced. There is a risk.

  An object of the present invention is to provide a variable valve operating apparatus for an internal combustion engine that can improve controllability when changing the maximum lift amount.

  A variable valve operating apparatus for an internal combustion engine that solves the above problems includes a control shaft that determines a maximum lift amount of an engine valve by an axial position, a cam that displaces the control shaft along the axial direction, and a rotation of the cam. A control section for controlling the drive section to be driven, and the cam surface of the cam has a change section in which the cam diameter gradually increases in one direction and the maximum lift amount changes, and the maximum lift amount is a constant value. Are held alternately, and when the control unit increases the maximum lift amount toward the target maximum lift amount, the control section starts from the holding section corresponding to the target maximum lift amount. After the cam is driven up to the changing section having a large cam diameter, the driving of the cam is stopped. The cam diameter means a radius from the rotation center of the cam to the cam surface.

  In the above configuration, when the maximum lift amount is increased toward the target maximum lift amount, the cam is driven to a change section having a larger cam diameter than the holding section corresponding to the target maximum lift amount. In this way, when the cam is driven to a changing section having a larger cam diameter than the holding section, the rotational torque described above, that is, the torque generated due to the axial force applied to the control shaft, the maximum lift amount is Torque is generated to rotate the cam in the direction of decreasing. The cam that is rotationally driven to the changing section by the urging force of the rotational torque is directed toward the holding section corresponding to the target maximum lift amount in the direction in which the maximum lift amount decreases, that is, from the above-described changing section. Will turn itself. Therefore, even if driving of the cam is stopped after the cam has been driven to the above-described change interval, the rotation phase of the cam causes the rotation phase of the cam to be within the holding interval corresponding to the target maximum lift amount. It changes to the phase, and the maximum lift amount is held at a constant value at the lift amount corresponding to the holding section.

  As described above, in the same configuration, when the maximum lift amount is increased toward the target maximum lift amount, the cam is temporarily driven to the above-described changing section to generate a rotational torque in the cam. Since the rotational phase of the cam naturally converges to the phase in the holding section due to the generated rotational torque, the controllability when changing the maximum lift amount is enhanced.

  With respect to the variable valve operating apparatus for an internal combustion engine, the control unit drives the cam to the changing section having a cam diameter larger than the holding section corresponding to the target maximum lift amount as a target value for the maximum lift amount. By setting a first target value and a second target value for driving the cam to the holding section corresponding to the target maximum lift amount, and setting a target value for the maximum lift amount to the first target value The cam is driven to the changing section having a cam diameter larger than the holding section corresponding to the target maximum lift amount, and then the target value related to the maximum lift amount is changed to the second target value. It is preferable that the cam is driven to the holding section corresponding to the maximum lift amount, and the driving of the cam is stopped after the cam is driven to the holding section. .

  According to the above configuration, when the first target value is set as the target value related to the maximum lift amount, the cam is driven to a change section having a larger cam diameter than the holding section corresponding to the target maximum lift amount. . Therefore, it is possible to reliably generate the rotational torque that acts in the direction in which the maximum lift amount decreases.

  Further, after the cam is driven to the change section, the target value related to the maximum lift amount is changed from the first target value to the second target value. Therefore, it is possible to reliably drive the cam driven to the change section to the holding section corresponding to the target maximum lift amount.

  Here, when the cam drive is stopped immediately after the cam is driven to the change section, the rotational torque when the cam rotates from the change section toward the holding section is generated due to the axial force. However, in this configuration, the drive torque from the drive unit is also applied. Therefore, the cam rotates more rapidly from the change section toward the holding section, thereby shortening the time required for changing the maximum lift amount.

  In the variable valve system for an internal combustion engine, the control unit sets the target value related to the maximum lift amount to the first target value, and then the rotation phase of the cam corresponds to the target maximum lift amount. It is preferable that the target value related to the maximum lift amount is changed from the first target value to the second target value when the rotational phase is within the changing section having a cam diameter larger than the section.

  In the above configuration, by setting the target value related to the maximum lift amount to the above-described first target value, the cam is driven to the changing section where the cam diameter is larger than the holding section corresponding to the target maximum lift amount. After the first target value is set, when the rotational phase of the cam is the rotational phase in the changing section having a larger cam diameter than the holding section corresponding to the target maximum lift amount, the rotational phase of the cam is The change section is reached beyond the holding section. Therefore, the rotational torque that acts in the direction in which the maximum lift amount decreases, that is, torque that rotates the cam from the change section toward the holding section is generated. Therefore, in the same configuration, after setting the target value related to the maximum lift amount to the first target value, the rotation phase of the cam rotates within the change interval where the cam diameter is larger than the holding interval corresponding to the target maximum lift amount. When the phase is reached, the target value related to the maximum lift amount is changed from the first target value to the second target value. Accordingly, the cam is driven at an earlier time than when the cam is driven until the first target value set in the change section is reached and then the target value related to the maximum lift amount is changed to the second target value. The direction can be switched from the change section direction to the holding section direction. Therefore, for example, the change time of the maximum lift amount can be shortened.

In the variable valve operating apparatus for an internal combustion engine, it is preferable that a cam diameter is constant in the holding section.
According to the above configuration, the amount of displacement of the control shaft by the cam is constant, so that the maximum lift amount is held at a constant value in the holding section. Further, on the cam surface having a constant cam diameter, even if the above-described axial force is applied, generation of a component force from the axial force can be suppressed. Therefore, it is difficult for the cam to generate the rotational torque that acts in the direction in which the maximum lift amount decreases. Therefore, in this holding section, the holding force (for example, the driving force of the drive unit) for holding the maximum lift amount at a constant value can be suppressed, and in some cases, the holding force can be set to “0”. become.

In the variable valve operating apparatus for an internal combustion engine, the holding section preferably has a minimum point at which the cam diameter changes from decreasing to increasing.
According to the above configuration, when the rotational phase of the cam deviates from the minimum point, the cam diameter of the cam surface increases and the maximum lift amount increases. Here, as described above, the component force of the axial force acts on the cam surface where the cam diameter of the cam surface increases, and the rotational torque acting in the direction of decreasing the maximum lift amount acts on the cam. Therefore, when the rotational phase of the cam deviates from the minimum point, the cam rotates so that the rotational phase of the cam is directed toward the minimum point due to the action of rotational torque acting in the direction in which the maximum lift amount decreases. Even if the rotational phase of the cam deviates from the minimum point in this way, the rotational phase of the cam eventually converges toward the minimum point. Therefore, the maximum lift amount can be held at the maximum lift amount corresponding to the rotation phase of the minimum point.

The fragmentary sectional view which shows the partial structure of an internal combustion engine. The fracture | rupture perspective view which shows the perspective structure of the variable part with which a variable valve apparatus is provided with an internal structure. The schematic diagram which shows the typical structure of a variable valve apparatus. The figure which shows the cam diagram and cam profile of the cam with which a variable valve apparatus is provided. The graph which shows the change of the maximum lift amount of the engine valve by a variable valve apparatus. The graph which shows the change of the rotational torque which arises in a cam. The flowchart which shows the procedure of a target value setting process. The timing chart which shows the change of the maximum lift amount when the maximum lift amount is enlarged. The timing chart which shows the change of the maximum lift amount when the maximum lift amount is made small. The graph which shows the setting mode of the target value when changing the maximum lift amount.

With reference to FIGS. 1 to 9, the configuration of an embodiment of a variable valve operating apparatus for an internal combustion engine will be described.
[Partial configuration of internal combustion engine]
A partial configuration of the internal combustion engine will be described with reference to FIG.

  As shown in FIG. 1, a plurality of cylindrical cylinders 12 are formed in a cylinder block 11 of the internal combustion engine 10, and a piston 13 is accommodated in each cylinder 12. A cylinder head 20 is assembled to the upper part of the cylinder block 11, and a combustion chamber 14 is defined by the inner peripheral surface of the cylinder 12, the upper surface of the piston 13 in the cylinder 12, and the lower surface of the cylinder head 20. Yes.

  In the cylinder head 20, for example, two intake passages 21 and two exhaust passages 22 connected to the combustion chamber 14 are formed for each combustion chamber 14. One intake passage 21 and one exhaust passage 22 may be formed for each combustion chamber 14. An intake port 23 is formed at a connection portion between the intake passage 21 and the combustion chamber 14, and an exhaust port 24 is formed at a connection portion between the exhaust passage 22 and the combustion chamber 14.

  The intake port 23 is provided with an intake valve 31 that opens and closes the opening of the intake port 23 to allow the combustion chamber 14 and the intake passage 21 to communicate with each other or to be shut off. An exhaust valve 41 is provided that opens and closes the opening of the port 24 to allow the combustion chamber 14 and the exhaust passage 22 to communicate with each other or to be shut off. The intake valve 31 is biased in the direction of closing the intake port 23 by the valve spring 32, that is, the valve closing direction, and the exhaust valve 41 is biased in the direction of closing the exhaust port 24 by the valve spring 42, that is, the valve closing direction. Yes.

  One end of each rocker arm 51 is in contact with the upper end of each of the intake valve 31 and the exhaust valve 41, and the other end of each rocker arm 51 is supported by a lash adjuster 52 disposed in the cylinder head 20. A roller 51 a is attached to each rocker arm 51 in a state where the roller 51 a can rotate without changing the rotation center with respect to the rocker arm 51.

  An intake camshaft 33 that drives the intake valve 31 and an exhaust camshaft 43 that drives the exhaust valve 41 are supported on the cylinder head 20 in a state in which the cylinder head 20 can rotate without changing the position of each rotation center. The intake camshaft 33 and the exhaust camshaft 43 extend along the direction in which the cylinders 12 are arranged. A plurality of intake cams 34 are formed on the outer peripheral surface of the intake camshaft 33, and a plurality of exhaust cams 44 are formed on the outer peripheral surface of the exhaust camshaft 43.

  Among these, the outer peripheral surface of the exhaust cam 44 is in contact with the roller 51 a of the rocker arm 51 that is in contact with the upper end of the exhaust valve 41. Therefore, when the exhaust camshaft 43 rotates, the rocker arm 51 swings with the end portion supported by the lash adjuster 52 as a fulcrum. As a result, the end of the rocker arm 51 on the exhaust valve 41 side rotates toward the cylinder block 11, and the exhaust valve 41 is pushed down into the cylinder 12, thereby opening the exhaust valve 41.

  On the other hand, a variable portion 60 that changes the maximum lift amount, which is one of the valve characteristics of the intake valve 31, is disposed for each cylinder 12 between the rocker arm 51 and the intake cam 34 that are in contact with the upper end of the intake valve 31. Has been. The variable portion 60 may be arranged not only between the intake cam 34 and the rocker arm 51 in contact with the intake cam 34 but also between the exhaust cam 44 and the rocker arm 51 in contact with the exhaust cam 44. The variable portion 60 may be disposed only on the exhaust cam 44 side.

  The variable portion 60 includes a support pipe 61 fixed to the cylinder head 20, and the input arm 62 and the output arm 63 are attached to the outer peripheral surface of the support pipe 61 in a state where the input arm 62 and the output arm 63 can swing around the support pipe 61. It has been. The rocker arm 51 that is in contact with the intake valve 31 is biased toward the output arm 63 by the valve spring 32, and the roller 51 a is in contact with the outer peripheral surface of the output arm 63.

  The variable portion 60 is formed with a protrusion 64. The protrusion 64 is urged by a spring 25 fixed in the cylinder head 20. Thereby, the roller 62 a of the input arm 62 is always in contact with the outer peripheral surface of the intake cam 34.

  When the intake camshaft 33 rotates, the input arm 62 and the output arm 63 swing around the support pipe 61. When the rocker arm 51 is pushed by the output arm 63, the rocker arm 51 swings with the end portion supported by the lash adjuster 52 as a fulcrum. As a result, the end of the rocker arm 51 on the side of the intake valve 31 rotates toward the cylinder block 11, and the intake valve 31 is pushed down into the cylinder 12, thereby opening the intake valve 31.

  A control shaft 65 that extends along the axial direction, which is the direction in which the central axis of the support pipe 61 extends, and moves along the axial direction is passed through the support pipe 61. In the variable section 60, the relative phase difference (angle θ shown in FIG. 1) between the input arm 62 and the output arm 63 with the support pipe 61 as the center is changed by changing the position of the control shaft 65 in the axial direction. .

[Configuration of variable part]
With reference to FIG. 2, the structure of the variable part 60 with which a variable valve apparatus is provided is demonstrated in detail.
As shown in FIG. 2, in the variable unit 60, an input unit 70 including an input arm 62 and two output units 80 sandwiching the input unit 70 are attached to the outer peripheral surface of the support pipe 61. The housing 71 of the input unit 70 and the housing 81 of each output unit 80 have a hollow cylindrical shape.

  A helical spline 72 is formed on the inner peripheral surface of the housing 71 of the input unit 70, and a helical spline whose tooth trace is opposite to that of the helical spline 72 of the input unit 70 is formed on the inner peripheral surface of the housing 81 of each output unit 80. A spline 82 is formed.

  A slider gear 90 is disposed in a space formed by the inner peripheral surface of the housing 71 of the input unit 70 and the inner peripheral surface of the housing 81 of each output unit 80. The slider gear 90 has a hollow cylindrical shape, and can move forward and backward in the axial direction of the support pipe 61 on the outer peripheral surface of the support pipe 61. It is arranged in a state that allows relative rotation.

  A helical spline 91 that meshes with the helical spline 72 of the input unit 70 is formed on the outer peripheral surface of the slider gear 90 at the central portion in the axial direction. In addition, on the outer peripheral surface of the slider gear 90, one helical spline 92 that meshes with the helical spline 82 of each output portion 80 is formed on each end in the axial direction.

  A control shaft 65 that can change its position in the axial direction of the support pipe 61 is passed through the support pipe 61. A slider gear 90 is arranged on the control shaft 65 so as to be able to rotate around the support pipe 61 and to move in the axial direction together with the control shaft 65.

  In the variable portion 60, when the control shaft 65 moves in the axial direction, the slider gear 90 moves in the axial direction as the control shaft 65 moves. The helical spline 91 and the helical spline 92 formed on the outer peripheral surface of the slider gear 90 have mutually different tooth trace formation directions, and each of the helical splines 91 and 92 includes the helical spline 72 of the input unit 70 and the output. It meshes with the helical spline 82 of the portion 80. Therefore, when the slider gear 90 moves in the axial direction, the input unit 70 and the output unit 80 rotate relative to each other in opposite directions around the support pipe 61. As a result, the relative phase difference between the input arm 62 and the output arm 63 changes, and the maximum lift amount of the intake valve 31 is changed.

  For example, when the control shaft 65 moves in the arrow Hi direction shown in FIG. 2, the slider gear 90 moves in the arrow Hi direction together with the control shaft 65. As a result, the relative phase difference between the input arm 62 and the output arm 63 (angle θ shown in FIG. 1) increases, and the maximum lift amount VL of the intake valve 31 increases, so that the intake air amount increases.

  On the other hand, when the control shaft 65 moves in the decreasing direction of the arrow Lo shown in FIG. 2, the slider gear 90 also moves in the arrow Lo direction together with the control shaft 65. As a result, the relative phase difference between the input arm 62 and the output arm 63 is reduced, and the maximum lift amount VL of the intake valve 31 is reduced, thereby reducing the intake air amount.

[Configuration of variable valve gear]
With reference to FIGS. 3 to 6, the configuration of the variable valve operating apparatus will be described. In the following description, the overall configuration of the variable valve operating apparatus, the cam provided in the variable valve operating apparatus, the maximum lift amount of the intake valve 31, and the rotational torque generated in the cam will be described in this order.

  As shown in FIG. 3, the variable valve apparatus 100 includes a motor 110 as a drive unit, a speed reduction unit 120 that reduces the rotational speed of the motor 110, and a conversion that converts the rotational motion of the speed reduction unit 120 into linear motion of the control shaft 65. Part 130 is provided. The motor 110 is provided with a rotation angle sensor 100A that detects the rotation angle of the motor 110.

  The speed reduction unit 120 is provided with a plurality of gears and the like. The output shaft of the motor 110 is connected to the input shaft of the speed reduction unit 120, and the cam 135 provided in the conversion unit 130 is connected to the output shaft of the speed reduction unit 120.

  The conversion unit 130 includes a holder 131 and a guide 132 that guides the movement of the holder 131, and the holder 131 moves forward and backward along the guide 132. A connection shaft 133 extending toward the control shaft 65 is attached to the holder 131, and an end portion of the connection shaft 133 is coupled to an end portion of the control shaft 65 on the connection shaft 133 side by a coupling portion 134.

  A cam 135 that is rotated by the output shaft of the speed reducing unit 120 is disposed in the holder 131. A roller 136 that is in contact with the cam surface of the cam 135 is rotatably attached to the holder 131.

  When the cam 135 rotates, the holder 131 as a follower, which is a member to which the movement of the cam 135 is transmitted, moves along the guide 132. As the holder 131 moves, the control shaft 65 is displaced in the axial direction, which is the direction in which the central axis of the control shaft 65 extends.

  The motor 110 is connected to a motor control device 110 </ b> C as a control unit that controls driving of the motor 110. The rotation angle of the motor 110 is controlled in accordance with a drive signal from the motor control device 110C. An engine control device 10C that controls the operating state of the internal combustion engine 10 is connected to the motor control device 110C.

  The engine control device 10C 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 apparatus 10C calculates the required intake air amount according to the engine operating state based on, for example, the engine rotation speed calculated from the accelerator operation amount and the crank angle, and the intake air from which the required intake air amount is obtained. The maximum lift amount of the 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 manner, the motor control device 110C calculates the rotational phase of the cam 135 corresponding to the target lift amount VLp, and the motor 110 has the calculated rotational phase. Control the rotation angle. The motor control device 110C calculates the rotational phase of the cam 135 from the rotational angle of the motor 110 detected by the rotational angle sensor 100A, and calculates the actual maximum lift amount VL from the calculated rotational phase. Then, the drive of the cam 135, that is, the drive amount (drive torque) of the motor 110 is set so that the target lift amount VLp and the actual maximum lift amount VL are equal to each other. Feedback control is performed based on the deviation or the like.

Next, the cam 135 that displaces the control shaft 65 will be described in detail.
As shown in FIG. 4, the cam surface of the cam 135 has a change section (first rotation phase R1 shown in FIG. 4) in which the cam diameter (radius from the cam rotation center to the cam surface) gradually increases in one direction. To the second rotation phase R2 and the third rotation phase R3 to the fourth rotation phase R4). Further, the cam surface of the cam 135 has a holding section where the cam diameter is constant and does not change (second rotation phase R2 to third rotation phase R3 shown in FIG. 4, fourth rotation phase R4 to fifth rotation phase). A section R5 and a section before the first rotation phase R1 in which the roller 136 contacts the reference circle 135a of the cam 135 are also provided.

  In the following description, the cam 135 is rotated clockwise (in FIG. 4, clockwise) in the direction in which the rotational phase of the cam 135 is changed from the first rotational phase R1 to the second rotational phase R2 and the third rotational phase R3. The direction of rotation) is defined as the direction in which the rotation phase is increased.

  When the rotational phase of the cam 135 increases while the roller 136 is in contact with the changing section, the movement amount of the control shaft 65 increases linearly. On the other hand, when the rotational phase of the cam 135 increases while the roller 136 is in contact with the holding section, the movement amount of the control shaft 65 is kept constant.

  When the rotational phase of the cam 135 is within the first holding section that is less than or equal to the first rotational phase R1, the displacement amount of the control shaft 65 is maintained at “0”. The displacement is the amount of movement of the control shaft 65 from the reference position in the axial direction, and the axial position of the control shaft 65 is the reference in the range where the rotational phase of the cam 135 is equal to or less than the first rotational phase R1. The displacement amount is “0”.

  When the rotational phase of the cam 135 is within the first change interval that is greater than the first rotational phase R1 and less than the second rotational phase R2, the displacement amount of the control shaft 65 increases as the rotational phase of the cam 135 increases. It grows linearly.

  When the rotational phase of the cam 135 is in the second holding section that is in the range from the second rotational phase R2 to the third rotational phase R3, the displacement amount of the control shaft 65 is the first displacement amount L1 that is a constant displacement amount. To be kept.

  When the rotational phase of the cam 135 is in the second change interval that is greater than the third rotational phase R3 and less than the fourth rotational phase R4, the displacement amount of the control shaft 65 increases as the rotational phase of the cam 135 increases. It becomes linearly larger than one displacement amount L1.

  When the rotational phase of the cam 135 is in the third holding section that is in the range from the fourth rotational phase R4 to the fifth rotational phase R5, the displacement amount of the control shaft 65 is a constant displacement larger than the first displacement amount L1. The second displacement amount L2, which is the amount, is maintained.

Since the cam surface of the cam 135 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 135 rotates once.
As shown in FIG. 5, as the rotational angle of the motor 110 increases, the rotational phase of the cam 135 gradually increases. When the rotational phase of the cam 135 is within the first holding section (the first rotational phase R1 or less), the roller 136 is in contact with the reference circle 135a of the cam 135, so the displacement amount of the control shaft 65 is “0. Is. At this time, the maximum lift amount VL of the intake valve 31 is maintained at the first lift amount VL1. The first lift amount VL1 is the minimum value of the maximum lift amount VL that can be varied.

  When the rotational phase of the cam 135 is within the first change interval (the first rotational phase R1 to the second rotational phase R2), the rotational phase increases, and accordingly the displacement amount of the control shaft 65 gradually increases. The maximum lift amount VL gradually becomes larger than the first lift amount VL1.

  When the rotational phase of the cam 135 is within the second holding section (second rotational phase R2 to third rotational phase R3), the displacement amount of the control shaft 65 remains the first displacement amount L1 even if the rotational phase changes. Kept. Accordingly, the maximum lift amount VL in the first holding section is maintained at the second lift amount VL2 that is larger than the first lift amount VL1.

  When the rotational phase of the cam 135 is within the second change section (the third rotational phase R3 to the fourth rotational phase R4), the displacement amount of the control shaft 65 gradually increases as the rotational phase increases. The lift amount VL becomes gradually larger than the second lift amount VL2.

  When the rotational phase of the cam 135 is within the third holding section (fourth rotational phase R4 to fifth rotational phase R5), the displacement amount of the control shaft 65 remains the second displacement amount L2 even if the rotational phase changes. Kept. Therefore, the maximum lift amount VL is maintained at the 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 that can be varied.

  Here, since the reaction force of the valve spring 32 acts on the output portion 80 of the variable portion 60, a force is applied to reduce the relative phase difference between the input arm 62 and the output arm 63. Accordingly, an axial force acts on the slider gear 90 and the control shaft 65 in the direction in which the maximum lift amount of the intake valve 31 is reduced (the direction of the arrow Lo shown in FIGS. 2 and 3).

  As shown in FIG. 6, such an axial force changes in the cam 135 in the change interval (the first rotation phase R1 to the second rotation phase R2, the third rotation phase R3 to the fourth rotation phase) in which the displacement amount of the control shaft 65 is changed. When acting on the cam surface of R4), a component force is generated from the axial force, and due to the component force, a rotational torque acting on the cam 135 in a direction in which the maximum lift amount VL decreases is exerted. Therefore, when the maximum lift amount VL is to be held within the change section, it is necessary to generate a holding force against the rotational torque from the motor 110, and it is necessary to supply a holding current to the motor 110. .

  On the other hand, when the axial force acts on the cam surface of the holding section described above in the cam 135, that is, the axial force is applied to the cam surface of the holding section where the cam diameter is constant and the displacement of the control shaft 65 is held constant. Even when such an axial force is applied, the generation of a component force from the axial force is suppressed. Therefore, it is difficult for the cam 135 to generate rotational torque that acts in the direction in which the maximum lift amount VL decreases. Therefore, in this holding section, the holding force for holding the maximum lift amount VL at a constant value can be suppressed, the holding current supplied to the motor 110 can be reduced, and in some cases the holding current is “0”. It is also possible to make it.

  Therefore, the variable valve apparatus 100 uses any one of the first lift amount VL1, the second lift amount VL2, and the third lift amount VL3 as the target lift amount VLp of the intake valve 31 according to the engine operating state. select. The maximum lift amount VL of the intake valve 31 is changed in three stages by holding the selected maximum lift amount.

  By the way, if the rotational torque described above is applied when the maximum lift amount VL is increased, the rotational direction of the cam 135 and the operational direction of the rotational torque are reversed, so that the controllability when changing the maximum lift amount VL is improved. May decrease.

  For example, when the maximum lift amount VL is increased from the first lift amount VL1 to the second lift amount VL2, the rotation phase of the cam 135 that was in the first holding section (first rotation phase R1 or less) is changed to the first. It is necessary to drive the cam 135 to change in the order of the section (first rotation phase R1 to second rotation phase R2) and the second holding section (second rotation phase R2 to third rotation phase R3). Here, in the first change section, the direction of rotation of the cam 135 and the direction of operation of the rotational torque are reversed, and the rotational speed of the cam 135 tends to decrease, so the driving torque of the motor 110 is made relatively large. . On the other hand, since the rotational torque decreases when the second holding section is reached, the driving torque of the motor 110 is reduced, but immediately after the rotational phase of the cam 135 changes from the first change section to the second holding section, Rotational torque is greatly reduced. Therefore, the drive torque of the motor 110 is excessively large until it is adjusted to the drive torque corresponding to the reduced rotational torque, and the time until the rotational phase of the cam 135 converges to a constant phase. Since it becomes long, the controllability regarding the drive of the cam 135 may fall.

  Therefore, the variable valve apparatus 100 of the present embodiment increases the controllability when changing the maximum lift amount VL by executing the target value setting process shown in FIG. 7 when setting the target lift amount VLp. I am doing so.

[Change processing of maximum lift amount]
With reference to FIG. 7 to FIG. 9, the processing procedure when the motor control device 110C changes the maximum lift amount VL of the intake valve 31 will be described. In the following, the maximum lift amount VL of the intake valve 31 is changed when the first lift amount VL1 is changed to the second lift amount VL2, and when the third lift amount VL3 is changed to the second lift amount VL2. A process for setting the target value of the lift amount VL will be described.

  As shown in FIG. 7, the motor control device 110C first determines whether or not a command for changing the maximum lift amount has been issued (S101). When the maximum lift amount change command is not issued (step S101: NO), this process is terminated.

  On the other hand, when a command for changing the maximum lift amount is issued (step S101: YES), the first target value TA is set as the target lift amount VLp (step S102). The first target value TA is a target value for driving the cam 135 to a changing section having a larger cam diameter than the holding section corresponding to the target maximum lift amount. In the present embodiment, the first target value TA is the second lift value. A lift amount larger than the amount VL2 and smaller than the third lift amount VL3 is set. When the first target value TA is set in this way, the cam 135 is driven so that the maximum lift amount VL and the first target value TA coincide.

  Next, the motor control device 110C determines whether the current maximum lift amount VL is larger than the second target value TB while the maximum lift amount VL of the intake valve 31 is being increased. (S103). The second target value TB is a target value for driving the cam 135 to the holding section corresponding to the target maximum lift amount, and in this embodiment, the same lift amount as the second lift amount VL2 is set. Has been.

  When the maximum lift amount VL of the intake valve 31 is being increased and the current maximum lift amount VL is larger than the second target value TB (S103: YES), the motor control device 110C is The target lift amount VLp is changed from the first target value TA to the second target value TB (step S104). When the target lift amount VLp is changed to the second target value TB in this way, the cam 135 is driven so that the maximum lift amount VL and the second target value TB coincide.

  Next, the motor control apparatus 110C determines whether or not the maximum lift amount VL has converged to the second target value TB by comparing the target lift amount VLp and the actual maximum lift amount VL (step S105). . The motor control device 110C, for example, converges the maximum lift amount VL to the second target value TB when the deviation between the second target value TB and the maximum lift amount VL becomes small enough that there is no hindrance to engine operation. It is determined that

  When the maximum lift amount VL has not converged to the second target value TB (step S105: NO), the determination process in step S105 is repeated until the maximum lift amount VL converges to the second target value TB. When the maximum lift amount VL converges to the second target value TB (step S105: YES), the motor control device 110C stops driving the motor 110 (S106) and ends this process.

  On the other hand, when a negative determination is made in step S103 (S103: NO), that is, when the maximum lift amount VL of the intake valve 31 is being reduced, or the current maximum lift amount VL is equal to or less than the second target value TB. If so, the motor control device 110C executes the process of step S107.

  In step S107, the motor control device 110C is in the process of decreasing the maximum lift amount VL of the intake valve 31, and the current maximum lift amount VL is equal to or less than the first target value TA. Determine whether.

  When the maximum lift amount VL of the intake valve 31 is being reduced and the current maximum lift amount VL is less than or equal to the first target value TA (S107: YES), the motor control device 110C is Then, the process of step S104 described above is executed to change the target lift amount VLp from the first target value TA to the second target value TB.

  Next, the motor control device 110C executes the process of step S105 described above, and when the maximum lift amount VL converges to the second target value TB (step S105: YES), the drive of the motor 110 is stopped (S106). ), This process is terminated.

  On the other hand, when a negative determination is made in step S107, that is, when the maximum lift amount VL of the intake valve 31 is not being reduced, or when the current maximum lift amount VL is larger than the first target value TA. The motor control device 110C executes the processing from step S102 onward.

  Next, changes in the maximum lift amount when the target value setting process is executed will be described with reference to FIGS. FIG. 8 shows a change in the maximum lift amount when the maximum lift amount VL is increased from the first lift amount VL1 to the second lift amount VL2. FIG. 9 shows changes in the maximum lift amount when the maximum lift amount VL is decreased from the third lift amount VL3 to the second lift amount VL2. 8 and 9, the change in the target lift amount VLp is indicated by a solid line, and the actual change in the maximum lift amount VL is indicated by a one-dot chain line.

  As shown in FIG. 8, when the maximum lift amount VL that has been the first lift amount VL1 is increased toward the target second lift amount VL2, first, the first target value is set as the target lift amount VLp. TA is set (time t1). As a result, the rotational phase of the cam 135 increases so that the maximum lift amount VL that has been the first lift amount VL1 increases to a lift amount that exceeds the second lift amount VL2.

  When the rotational phase of the cam 135 reaches the second rotational phase R2 at time t2, the maximum lift amount VL remains constant at the second lift amount VL2 until the third rotational phase R3 is reached thereafter.

  At time t3, when the rotational phase of the cam 135 becomes the third rotational phase R3, and when the rotational phase of the cam 135 exceeds the third rotational phase R3 and reaches the second change section (after time t3), the maximum lift amount VL. Is larger than the second lift amount VL2 set as the second target value TB, and therefore an affirmative determination is made in the process of step S103 shown in FIG. As a result, the target lift amount VLp is changed from the first target value TA to the second target value TB. When the target lift amount VLp is changed from the first target value TA to the second target value TB in this way, the rotational phase of the cam 135 decreases from increase to decrease when the rotational inertia of the cam 135 and the like is settled (time t4). Turn. After time t4, the cam 135 is driven so as to return to the second holding section. When the maximum lift amount VL reaches the second target value TB at time t5, that is, when the rotational phase of the cam 135 returns to the third rotational phase R3, the maximum lift amount VL is equal to or greater than the second lift after time t5. It converges to the quantity VL2.

  On the other hand, as shown in FIG. 9, when the maximum lift amount VL that has been the third lift amount VL3 is decreased toward the target second lift amount VL2, the first target lift amount VLp is first set as the first target lift amount VLp. A value TA is set (time t1). As a result, the rotational phase of the cam 135 becomes small so that the maximum lift amount VL that has been the third lift amount VL3 is reduced to the lift amount between the third lift amount VL3 and the second lift amount VL2. Go.

  Then, the rotational phase of the cam 135 becomes a phase within the second change section (fourth rotational phase R4 to third rotational phase R3), and the maximum lift amount VL is set as the first target value TA at time t2. When it becomes smaller than the maximum lift amount VL, an affirmative determination is made in the processing of step S107 shown in FIG. 7, and as a result, the target lift amount VLp is changed from the first target value TA to the second target value TB. When the target lift amount VLp is changed from the first target value TA to the second target value TB in this way, the cam 135 is driven toward the second holding section (third rotation phase R3 to second rotation phase R2). . Then, at time t3, when the maximum lift amount VL reaches the second target value TB, that is, when the rotational phase of the cam 135 reaches the third rotational phase R3, the maximum lift amount VL becomes the second lift amount VL2 after time t3. Converge to. Here, when the target lift amount VLp is changed from the first target value TA to the second target value TB, the actual maximum lift amount VL approaches the second lift amount VL2 to some extent. Therefore, when the cam 135 is driven from the first target value TA toward the second lift amount VL2 that is the second target value TB, the cam 135 is directly driven from the third lift amount VL3 toward the second lift amount VL2. Compared with the case where it does, the control gain according to a deviation becomes small. Therefore, an undershoot that may occur when the maximum lift amount VL is decreased (when the maximum lift amount VL is decreased from the third lift amount VL3 to the second lift amount VL2, the rotation phase of the cam 135 is maintained at the second level). Occurrence of a phenomenon that passes through the section and rotates to the first change section is suppressed.

Next, the operation of this embodiment will be described.
When the maximum lift amount VL is increased toward the target second lift amount VL2, first, the first target value TA is set as the target lift amount VLp. Accordingly, the second change section (third rotation phase R3 to fourth rotation) having a cam diameter larger than the second holding section (second rotation phase R2 to third rotation phase R3) corresponding to the target second lift amount VL2. The cam 135 is driven up to the phase R4). In this way, when the cam 135 is driven to a changing section having a larger cam diameter than the holding section, the rotational torque described above, that is, the torque generated due to the axial force applied to the control shaft 65, is the maximum lift. Torque is generated to rotate the cam 135 in the direction in which the amount VL decreases. The cam 135 that is rotationally driven to the second change interval by the urging force of the rotational torque becomes the target second lift amount VL2 in the direction of decreasing the maximum lift amount VL, that is, from the above-described second change interval. It rotates by itself toward the direction of the corresponding second holding section. Therefore, even if driving of the cam 135 is stopped after driving the cam 135 until the second change interval described above, the rotational phase of the cam 135 is set to the target second lift amount VL2 by the action of the rotational torque. The phase changes to the phase in the corresponding second holding section, and the maximum lift amount VL is held at a constant value at the second lift amount VL2 corresponding to the second holding section.

  In this way, when the maximum lift amount VL is increased toward the target second lift amount VL2, the cam 135 is once driven until the above-described second change interval, and rotational torque is generated in the cam 135. Yes. The rotational phase of the cam 135 naturally converges to the phase in the second holding section due to the generated rotational torque, so that controllability when changing the maximum lift amount VL is enhanced.

  In addition, since the first target value TA is set as the target lift amount VLp, the cam 135 reaches the second change section having a larger cam diameter than the second holding section corresponding to the target second lift amount VL2. Is driven. Therefore, the rotational torque that acts in the direction in which the maximum lift amount VL decreases is reliably generated.

  Further, after the cam 135 is driven to the second change section, the target lift amount VLp is changed from the first target value TA to the second target value TB. Therefore, the cam 135 driven to the second change section is reliably driven to the second holding section corresponding to the target second lift amount VL2.

  Here, when the drive of the cam 135 is stopped immediately after the cam 135 is driven to the second change interval, the rotational torque when the cam 135 rotates from the second change interval toward the second holding interval is Only the rotational torque generated due to the axial force is obtained. However, in the present embodiment, the cam 135 is driven to the second holding section corresponding to the target second lift amount VL2 by changing the target lift amount VLp from the first target value TA to the second target value TB. doing. Then, when it is confirmed by the affirmative determination in step S105 shown in FIG. 7 that the cam 135 has been driven to the second holding section, the driving of the cam 135 is stopped thereafter. Therefore, the rotational torque when the cam 135 rotates from the second change section toward the second holding section is not only the rotational torque generated due to the axial force but also the driving torque from the motor 110. Become. Accordingly, the cam 135 rotates more rapidly from the second change section toward the second holding section, thereby reducing the time required for changing the maximum lift amount VL.

  Further, by setting the target lift amount VLp to the above-described first target value TA, the cam 135 is driven to the second change section having a larger cam diameter than the second holding section corresponding to the target second lift amount VL2. Is done. After setting the first target value TA, the rotational phase of the cam 135 becomes the rotational phase in the second change section having a larger cam diameter than the second holding section corresponding to the target second lift amount VL2. When the cam 135 is rotating, the rotation phase of the cam 135 exceeds the second holding section and reaches the second change section. Therefore, the rotational torque that acts in the direction in which the maximum lift amount VL decreases, that is, torque that rotates the cam from the second change section toward the second holding section is generated. Therefore, in the process of step S103 shown in FIG. 5, the first target value TA is set as the target lift amount VLp by determining whether or not the current maximum lift amount VL is larger than the second target value TB. After the setting, it is determined whether or not the rotational phase of the cam 135 has reached the rotational phase in the second change section having a larger cam diameter than the second holding section corresponding to the target second lift amount VL2. . When an affirmative determination is made in step S103, that is, the rotational phase of the cam 135 becomes the rotational phase in the second change section having a larger cam diameter than the second holding section corresponding to the target second lift amount VL2. The target lift amount VLp is changed from the first target value TA to the second target value TB. Therefore, the cam 135 is driven until the first target value TA set in the second change section is reached, and then the target lift amount VLp is changed to the second target value TB at an earlier time. The drive direction of the cam 135 can be switched from the second change section direction to the second holding section direction. Therefore, for example, the change time of the maximum lift amount VL is shortened.

As described above, according to the embodiment, the following effects can be obtained.
(1) When the actual maximum lift amount VL is increased toward the target maximum lift amount, the cam 135 is driven to a change section having a larger cam diameter than the holding section corresponding to the target maximum lift amount. The driving of the cam 135 is stopped. Therefore, the controllability when changing the maximum lift amount VL is enhanced.

  (2) As the target lift amount VLp, it corresponds to the first target value TA for driving the cam 135 to the changing section where the cam diameter is larger than the holding section corresponding to the target maximum lift amount, and the target maximum lift amount. The second target value TB for driving the cam 135 up to the holding section is set. Then, by setting the value of the target lift amount VLp to the value of the first target value TA, the cam 135 is driven to a change section having a larger cam diameter than the holding section corresponding to the target maximum lift amount. By changing the value of the target lift amount VLp to the value of the second target value TB, the cam 135 is driven to the holding section corresponding to the target maximum lift amount. Then, after the cam 135 is driven to the holding section, the drive of the cam 135 is stopped. Therefore, the time required for changing the maximum lift amount VL can be shortened as compared with the case where the driving of the cam 135 is stopped immediately when the cam 135 is driven to the above-described change interval.

  (3) After setting the value of the target lift amount VLp to the value of the first target value TA, the rotation phase of the cam 135 is within a change interval in which the cam diameter is larger than the holding interval corresponding to the target maximum lift amount. When the rotational phase is reached, the value of the target lift amount VLp is changed to the value of the second target value TB. Accordingly, the cam 135 is driven at an earlier time than when the target lift amount VLp is changed to the second target value TB after the cam 135 is driven until the first target value TA set in the change section is reached. The drive direction can be switched from the change section direction to the holding section direction. Therefore, for example, the change time of the maximum lift amount VL can be shortened.

  (4) In the holding section described above, the cam diameter is constant. Accordingly, the holding force for holding the maximum lift amount VL at a constant value can be suppressed, and in some cases, the holding force can be set to “0”.

In addition, the said embodiment can also be suitably changed and implemented as follows.
-The process of step S104 and step S105 shown in previous FIG. 7 is abbreviate | omitted. If an affirmative determination is made in step S103 or step S107, the process of step S106 may be executed to end the target value setting process. In this case, the drive of the motor 110 is stopped when the rotational phase of the cam 135 reaches the phase in the second change section. However, as described above, the cam 135 is caused by the axial force. Rotate in the direction of the second holding section by the rotating torque. Therefore, even in this case, the maximum lift amount VL can be changed to the second lift amount VL2, and the effects described in (1) and (4) above can be obtained.

  In step S103 shown in FIG. 7, it is determined that the current maximum lift amount VL is larger than the second target value TB, but instead the current maximum lift amount VL is It may be determined that the first target value TA has been reached. Even in this case, effects other than the above (3) can be obtained.

  The target value setting process shown in FIG. 7 may be performed only when the maximum lift amount VL is increased. In this modification, for example, the process of step S107 shown in FIG. 7 is omitted. And when negative determination is carried out in step S103, it can embody by performing the process after step S102.

  Although the drive of the cam 135 is controlled through feedback control, other control modes may be adopted. For example, the drive of the cam 135 may be controlled through feedforward control (open loop control). Even in this case, the maximum lift amount VL can be converged to the target maximum lift amount VL by using the rotational torque resulting from the axial force.

  The variable valve operating apparatus that changes the maximum lift amount VL of the engine valve in the above-described procedure may use the exhaust valve 41 as a target for changing the maximum lift amount VL, or may target both the intake valve 31 and the exhaust valve 41. Good.

  In the cam 135, four or more holding sections may be formed on the cam surface. When a plurality of holding sections are formed between the changing sections, when the maximum lift amount VL corresponding to each holding section is changed, the change processing of the maximum lift amount VL described in the above embodiment is performed. Can be adopted. An example of this modification will be described with reference to FIG.

  As shown in FIG. 10, the cam in this modification has four holding sections where the maximum lift amount VL is held constant. More specifically, in the first holding section, the maximum lift amount VL is held at the first lift amount VL1 that is the minimum value. Further, in the second holding section formed at a portion where the rotational phase of the cam is larger than that in the first holding section, the maximum lift amount VL is held at the second lift amount VL2 which is larger than the first lift amount VL1. Further, in the third holding section formed at a portion where the rotational phase of the cam is larger than that in the second holding section, the maximum lift amount VL is held at the third lift amount VL3 which is larger than the second lift amount VL2. Then, in the fourth holding section formed in the part where the rotational phase of the cam is larger than that in the third holding section, the maximum lift amount VL is larger than the third lift amount VL3, and the maximum maximum lift amount is variable. The value is held at the fourth lift amount VL4.

  On the other hand, a first change interval in which the maximum lift amount VL changes from the first lift amount VL1 toward the second lift amount VL2 is formed between the first holding interval and the second holding interval. Further, a second change section in which the maximum lift amount VL changes from the second lift amount VL2 toward the third lift amount VL3 is formed between the second holding section and the third holding section. A third change section in which the maximum lift amount VL changes from the third lift amount VL3 toward the fourth lift amount VL4 is formed between the third holding section and the fourth holding section.

  When such a cam is provided, when the maximum lift amount VL of the intake valve 31 is changed from the first lift amount VL1 to the second lift amount VL2, and when the third lift amount VL3 is changed to the second lift amount VL2, the maximum As the first target value TA of the lift amount VL, a lift amount that is larger than the second lift amount VL2 and smaller than the third lift amount VL3 is set (first target value TA1 shown in FIG. 10). Further, the same lift amount as the second lift amount VL2 is set as the second target value TB of the maximum lift amount VL (second target value TB1 shown in FIG. 10).

  Similarly, when the maximum lift amount VL of the intake valve 31 is changed from the second lift amount VL2 to the third lift amount VL3 and when the fourth lift amount VL4 is changed to the third lift amount VL3, the maximum lift amount VL is set. A lift amount larger than the third lift amount VL3 and smaller than the fourth lift amount VL4 is set as the first target value TA (first target value TA2 shown in FIG. 10). Further, the same lift amount as the third lift amount VL3 is set as the second target value TB of the maximum lift amount VL (second target value TB2 shown in FIG. 10).

  By performing such processing, when changing the maximum lift amount VL to the second lift amount VL2, or when changing to the third lift amount VL3, it is possible to obtain the same operational effects as in the above embodiment.

  In the holding section described above, the cam diameter is constant, but the maximum lift amount VL may be held in another shape. For example, a section having a minimum point where the cam diameter changes from decreasing to increasing may be formed as the holding section. In this case, when the rotational phase of the cam 135 deviates from the minimum point, the cam diameter of the cam surface increases and the maximum lift amount increases. Here, as described above, the component force generated from the axial force acts on the cam surface where the cam diameter of the cam surface increases, and the rotational torque acting in the direction of decreasing the maximum lift amount acts on the cam 135. . Therefore, when the rotational phase of the cam 135 deviates from the minimum point, the cam 135 rotates so that the rotational phase of the cam 135 is directed toward the minimum point due to the action of the rotational torque acting in the direction in which the maximum lift amount decreases. Even if the rotational phase of the cam 135 deviates from the minimum point in this way, the rotational phase of the cam 135 eventually converges toward the minimum point, so that the maximum lift amount VL is set to the rotational phase of the minimum point. Can be held at the maximum lift amount VL.

  The target lift amount VLp, which is the target value of the maximum lift amount VL itself, is set as the target value related to the maximum lift amount VL. In addition, the rotation phase of the cam 135 may be set as the target value as the target value related to the maximum lift amount VL. In this case, what is necessary is just to set the rotation phase in a change area as 1st target value TA. Moreover, what is necessary is just to set the maximum value in the rotation phase in a holding | maintenance area as 2nd target value TB. As the second target value TB, a rotation phase other than the maximum value in the holding section may be set.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 10C ... Engine control apparatus, 11 ... Cylinder block, 12 ... Cylinder, 13 ... Piston, 14 ... Combustion chamber, 20 ... Cylinder head, 21 ... Intake passage, 22 ... Exhaust passage, 23 ... Intake port, 24 ... exhaust port, 25 ... spring, 31 ... intake valve, 32, 42 ... valve spring, 33 ... intake camshaft, 34 ... intake cam, 41 ... exhaust valve, 43 ... exhaust camshaft, 44 ... exhaust cam, 51 ... Rocker arm, 51a ... Roller, 52 ... Rush adjuster, 60 ... Variable part, 61 ... Support pipe, 62 ... Input arm, 62a ... Roller, 63 ... Output arm, 64 ... Protrusion, 65 ... Control shaft, 70 ... Input part, 71, 81 ... housing, 72, 82, 91, 92 ... helical spline, 80 ... output section, 90 ... slider gear DESCRIPTION OF SYMBOLS 100 ... Variable valve apparatus, 100A ... Rotation angle sensor, 110 ... Motor, 110C ... Motor control device, 120 ... Deceleration part, 130 ... Conversion part, 131 ... Holder, 132 ... Guide, 133 ... Connection shaft, 134 ... Connection Part, 135 ... cam, 135a ... reference circle, 136 ... roller.

Claims (5)

A control shaft that determines the maximum lift amount of the engine valve by the position in the axial direction;
A cam for displacing the control shaft along the axial direction;
A control unit that controls a drive unit that rotates the cam;
On the cam surface of the cam, a changing section in which the cam diameter gradually increases in one direction and the maximum lift amount changes and a holding section in which the maximum lift amount is held at a constant value are alternately formed. And
The controller is
When increasing the maximum lift amount toward the target maximum lift amount, the cam is driven after the cam is driven to the changing section having a cam diameter larger than the holding section corresponding to the target maximum lift amount. A variable valve system for an internal combustion engine. The controller is
As a target value for maximum lift,
A first target value for driving the cam to the changing section having a larger cam diameter than the holding section corresponding to the target maximum lift amount, and the cam to the holding section corresponding to the target maximum lift amount Set the second target value to be
By setting the target value related to the maximum lift amount to the first target value, the cam is driven to the change section having a cam diameter larger than the holding section corresponding to the target maximum lift amount, and then the maximum lift By changing the target value related to the amount to the second target value, the cam is driven to the holding section corresponding to the target maximum lift amount, and after the cam is driven to the holding section, the cam The variable valve operating apparatus for an internal combustion engine according to claim 1. The controller is
After setting the target value related to the maximum lift amount to the first target value, the rotational phase of the cam is set to the rotational phase in the changing section having a cam diameter larger than the holding section corresponding to the target maximum lift amount. 3. The variable valve operating apparatus for an internal combustion engine according to claim 2, wherein the target value related to the maximum lift amount is changed from the first target value to the second target value. The variable valve operating apparatus for an internal combustion engine according to any one of claims 1 to 3, wherein the holding section has a constant cam diameter. The variable valve operating apparatus for an internal combustion engine according to any one of claims 1 to 3, wherein the holding section has a minimum point at which the cam diameter changes from decreasing to increasing.

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