JP2009115036A - Control device for variable valve gear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for a variable valve gear capable of suppressing influence of execution of a restriction on an engine operation state to the minimum upon restricting driving speed of an electric actuator for suppressing overheat of the electric actuator. <P>SOLUTION: A driving current CU of an electric motor for driving the variable valve gear is read (S100). When the driving current CU is a threshold value α or more (S110: YES), an addition value I is added to a counter value C (S120). When the driving current CU is less than the threshold value α (S110: NO), a subtraction value D is subtracted from the counter value C (S130). When the counter value C updated as such is a determination value CL or more (S140: YES), only an upper limit speed Smax of the electric motor when an operating angle INCAM of an intake valve is made small is reduced (S150). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device for a variable valve mechanism.

  Conventionally, various variable valve mechanisms for changing valve characteristics of engine valves such as an intake valve and an exhaust valve of an internal combustion engine using an electric actuator such as an electric motor have been proposed. For example, in the devices described in Patent Document 1, Patent Document 2, and the like, the direction of increase / decrease of the intake air amount by changing the valve characteristics is switched by switching the driving direction of the electric actuator.

  When such a variable valve mechanism is in operation, when the load on the electric actuator increases, the power supplied to the electric actuator increases, and the temperature of the electric actuator may become excessively high. If the temperature of the electric actuator becomes excessively high in this way, for example, the electrical resistance of the winding increases and the output torque decreases, the durability of the winding covering decreases due to thermal stress, and in some cases the winding May burn out.

  An example of an increase in the load on the electric actuator is a state where the intake air amount is increased and decreased frequently in a short cycle through the change of the valve characteristics. In such a state, the driving direction of the electric actuator is frequently switched in a short cycle, and when the driving direction of the electric actuator that has been rapidly driven in one direction is switched to the other direction, the variable valve It is necessary to cancel a relatively large inertial force in one direction that has been acting on the movable part of the mechanism or the electric actuator. Therefore, the load on the electric actuator tends to be very large.

Thus, for example, in the devices described in the above-mentioned documents, an excessive temperature rise of the electric actuator is suppressed by suppressing the power supplied to the electric actuator and limiting the driving speed.
Japanese Patent Laid-Open No. 2003-3900 JP 2005-218281 A

  By the way, when the valve characteristic of the engine valve is changed, it is desirable that the valve characteristic is quickly changed following the change of the engine operation state. In this regard, when the drive speed of the electric actuator is limited as described above, the output torque of the electric actuator is reduced during the limit, so that the operating speed of the variable valve mechanism is reduced. As described above, when the operating speed of the variable valve mechanism decreases, it becomes difficult to quickly change the valve characteristics. Therefore, the restriction on the driving speed has a considerable influence on the engine operating state.

  The present invention has been made in view of such circumstances, and its purpose is to limit the influence of the execution of the restriction on the engine operating state when restricting the driving speed of the electric actuator in order to suppress overheating of the electric actuator. It is an object of the present invention to provide a control device for a variable valve mechanism that can be suppressed as much as possible.

In the following, means for achieving the above object and its effects are described.
The invention according to claim 1 includes a variable valve mechanism that varies a valve characteristic of an engine valve of an internal combustion engine, and an electric actuator that drives the variable valve mechanism, and a driving direction of the electric actuator is switched. Thus, in the control apparatus for a variable valve mechanism that can switch the increase / decrease direction of the intake air amount through the change of the valve characteristic, the estimation means for estimating the load on the electric actuator, and the load estimated by the estimation means When a predetermined judgment value is exceeded, when the electric actuator is driven in one direction so that the driving speed when the electric actuator is driven in one direction is slower than the driving speed when the electric actuator is driven in the other direction The gist of the present invention is to provide limiting means for limiting the driving speed.

  According to this configuration, when the load on the electric actuator exceeds the determination value, the driving speed when the electric actuator is driven in one direction is made slower than the driving speed when the electric actuator is driven in the other direction. As described above, the electric actuator whose driving direction is switched is limited in the driving speed when driven in one direction, so that overheating of the electric actuator can be suppressed when driving in the one direction. Further, since the driving speed when driven in the other direction is not limited, the valve characteristic can be quickly changed when driving in the other direction. As described above, in the same configuration, when the load on the electric actuator exceeds the determination value, the driving speed of the electric actuator is not limited, but only the driving speed when driven in one direction is limited. Yes. Therefore, when limiting the drive speed of the electric actuator in order to suppress overheating of the electric actuator, it is possible to suppress as much as possible the influence of the execution of the restriction on the engine operating state.

  According to a second aspect of the present invention, in the control device for the variable valve mechanism according to the first aspect, the driving speed when driven in the one direction is such that the valve characteristic is in the direction in which the intake air amount is reduced. The gist is that the driving speed of the electric actuator is changed.

  According to this configuration, since the drive speed of the electric actuator when the valve characteristic is changed in the direction in which the intake air amount is increased is not limited, the engine output can be increased quickly.

  According to a third aspect of the present invention, in the control device for the variable valve mechanism according to the second aspect, when the intake air amount is adjusted through the change of the valve characteristic, the drive speed of the electric actuator is When the valve characteristic is changed in the direction in which the intake air amount is reduced in a state where the intake air amount is restricted, an opening degree reduction process for reducing the opening degree of the throttle valve provided in the intake passage of the internal combustion engine is performed. Is the gist.

  When the intake air amount is being adjusted through the change of the valve characteristic, the driving speed of the electric actuator when the valve characteristic is changed in the direction in which the intake air amount is reduced is limited by the limiting means. Since the rate of reduction of the intake air amount becomes slow, the output reduction and the rotational speed reduction of the internal combustion engine also become slow. In this regard, according to the same configuration, when the intake air amount is being adjusted by changing the valve characteristics, the valve is set in a direction in which the intake air amount is reduced while the drive speed of the electric actuator is limited. When the characteristic is changed, the opening of the throttle valve is forcibly reduced, so that the intake air amount is reduced quickly, so that the output and rotation speed of the internal combustion engine can be reduced quickly. become. Therefore, for example, in a vehicle including a control device having the same configuration, even if the drive speed of the electric actuator is changed when the valve characteristic is changed in the direction in which the intake air amount is reduced, the feeling of deceleration of the vehicle is preferable. Secured. In this configuration, it is desirable to reduce the opening of the throttle valve so that at least the reduction rate of the intake air amount that is reduced by limiting the drive speed of the electric actuator can be compensated. By the way, when the intake air amount is adjusted by changing the valve characteristics and adjusting the opening of the throttle valve, the driving speed of the electric actuator when the valve characteristics are changed in the direction in which the intake air amount is reduced. Even if it is restricted, the intake air amount is quickly reduced by adjusting the opening of the throttle valve. Therefore, in this case as well, the output and rotational speed of the internal combustion engine can be quickly reduced, and a feeling of deceleration of the vehicle is suitably ensured.

  According to a fourth aspect of the present invention, in the control apparatus for a variable valve mechanism according to any one of the first to third aspects, the limiting means is configured to control the driving speed according to the estimated magnitude of the load. The gist is to variably set the limit amount.

  According to this configuration, it is possible to appropriately set the limit amount for limiting the drive speed of the electric actuator according to the heat generation state of the electric actuator. In the same configuration, it is desirable to variably set the limit amount so that the driving speed decreases as the load increases.

  When the driving speed of the electric actuator is limited by the limiting means, for example, the amount of change in the driving speed per unit time, that is, the acceleration is limited, and in addition, according to the invention described in claim 5, An upper limit value is set for the maximum driving speed, and the upper limit value is set to a value lower than that when the driving speed is not limited when the driving speed is limited by the limiting means. You can also

  According to a sixth aspect of the present invention, in the control apparatus for a variable valve mechanism according to any one of the first to fifth aspects, the estimation means estimates the load based on power supplied to the electric actuator. The gist is to do.

  As the load on the electric actuator increases, the power supplied to the electric actuator increases. Therefore, as with the configuration, the load on the electric actuator is estimated based on the power supplied to the electric actuator. Is possible. In the same configuration, as a value indicating the supplied power, for example, a drive current of an electric actuator can be used. In the case of an electric actuator in which speed control is performed by duty control, a duty ratio can be used as a value indicating supplied power.

  According to a seventh aspect of the present invention, in the control device for a variable valve mechanism according to the sixth aspect, the estimation means is increased when the supplied power is equal to or higher than a preset threshold value, while satisfying the same threshold value. The gist is to estimate the load on the basis of a counter value that is decreased when there is not.

  According to this configuration, the counter value is increased when the load on the electric actuator is large and the temperature rises, and the counter value is decreased when the load on the electric actuator is small and the temperature decreases. In this way, the counter value reflects the increase / decrease history of the load on the electric actuator. If the counter value is large, the load on the electric actuator is averagely high, and the temperature of the electric actuator is high. It can be determined that Therefore, according to this configuration, it is possible to more appropriately estimate the state of the load that causes heat generation of the electric actuator.

  In addition, as a value which shows the supply electric power as mentioned above, the drive current of an electric actuator can be used, for example. In the case of an electric actuator in which speed control is performed by duty control, a duty ratio can be used as a value indicating supplied power.

Hereinafter, an embodiment in which a control device for a variable valve mechanism according to the present invention is embodied will be described with reference to FIGS.
As shown in FIGS. 1 and 2, an internal combustion engine mounted on a vehicle has a plurality of cylinders, and the cylinder head 2 communicates with an intake port 2 a communicated with an intake passage 3 and an exhaust passage. An exhaust port 2b is formed. On the upstream side of the intake passage 3, a throttle valve 4 for adjusting the intake air amount is provided. The opening degree of the throttle valve 4 is controlled by a control device 200 described later.

The intake port 2a is provided with an intake valve 10 constituting an engine valve, and the exhaust port 2b is provided with an exhaust valve 15 constituting an engine valve.
The cylinder head 2 is provided with an intake valve drive mechanism 40 and an exhaust valve drive mechanism 45 corresponding to the intake valve 10 and the exhaust valve 15, respectively.

  The exhaust valve drive mechanism 45 is provided with a lash adjuster 17 corresponding to each exhaust valve 15, and a rocker arm 18 is installed between the lash adjuster 17 and the exhaust valve 15. One end of the rocker arm 18 is supported by the lash adjuster 17 and the other end is in contact with the proximal end portion of the exhaust valve 15. A plurality of exhaust cams 8 are formed on the exhaust cam shaft 7 rotatably supported by the cylinder head 2, and the outer peripheral surfaces of the exhaust cams 8 abut on rollers 18 a provided on the rocker arm 18. Has been. The exhaust valve 15 is provided with a retainer 15 a and a valve spring 16 is provided between the retainer 15 a and the cylinder head 2. The exhaust valve 15 is urged in the valve closing direction by the urging force of the valve spring 16. As a result, the roller 18 a of the rocker arm 18 is pressed against the outer peripheral surface of the exhaust cam 8. When the exhaust cam 8 rotates during engine operation, the rocker arm 18 swings about a portion supported by the lash adjuster 17 as a fulcrum. As a result, the exhaust valve 15 is driven to open and close by the rocker arm 18.

  On the other hand, the intake valve drive mechanism 40 is provided with a valve spring 11, a retainer 10a, a rocker arm 12, a roller 12a, and a lash adjuster 13 as in the exhaust side. A plurality of intake cams 6 are formed on the intake camshaft 5 that is rotatably supported by the cylinder head 2.

  On the other hand, unlike the exhaust valve drive mechanism 45, the intake valve drive mechanism 40 is provided with a variable valve mechanism 20 that changes the valve characteristics of the intake valve 10 between the intake cam 6 and the rocker arm 12. The variable valve mechanism 20 changes the maximum lift amount and the operating angle of the intake valve 10 (a value that coincides with the valve opening period of the intake valve 10).

  The variable valve mechanism 20 has an input portion 23 and a pair of output portions 24, and the input portion 23 and the output portion 24 are swingably supported by a support pipe 22 fixed to the cylinder head 2. Yes. The rocker arm 12 is urged toward the output portion 24 by the proximal end portion of the intake valve 10 and the lash adjuster 13, and the roller 12 a is in contact with the outer peripheral surface of the output portion 24. Further, a spring 14 is provided between the input portion 23 and the cylinder head 2, and a roller 23 b provided in the input portion 23 is biased by the intake cam 6 by the biasing force of the spring 14. .

  When the intake cam 6 rotates during engine operation, the intake cam 6 presses the input portion 23 while being in sliding contact with the roller 23b, so that the output portion 24 swings in the circumferential direction of the support pipe 22. When the output unit 24 swings, the rocker arm 12 swings using the portion supported by the lash adjuster 13 as a fulcrum. As a result, the intake valve 10 is driven to open and close by the rocker arm 12.

Next, the structure of the variable valve mechanism 20 will be described in detail with reference to FIG.
As shown in FIG. 3, the input unit 23 is provided between the output units 24, and a substantially cylindrical communication space is formed inside the input unit 23 and the output unit 24. A helical spline 23a is formed on the inner peripheral surface of the input unit 23, and a helical spline 24a that is inclined in the opposite direction to the helical spline 23a of the input unit 23 is formed on the inner peripheral surface of the output unit 24. Yes.

  A substantially cylindrical slider gear 26 is provided in a space formed inside the input unit 23 and the output unit 24. A helical spline 26a that meshes with the helical spline 23a of the input portion 23 is formed at the center portion of the outer peripheral surface of the slider gear 26, and meshes with the helical spline 24a of the output portion 24 at both ends of the outer peripheral surface. A helical spline 26b is formed.

  Further, a groove 29 extending along the circumferential direction is formed on the inner wall of the substantially cylindrical slider gear 26, and a bush 28 is fitted in the groove 29. The bush 28 can slide on the inner peripheral surface of the groove 29 along the direction in which the groove 29 extends, but the displacement of the slider gear 26 in the axial direction is restricted.

  A support pipe 22 is inserted into the through space formed inside the slider gear 26. A control shaft 21 that can be driven along the axial direction of the support pipe 22 is inserted into the support pipe 22. A long hole 22 a extending in the axial direction is formed in the tube wall of the support pipe 22. A locking pin 27 is provided between the slider gear 26 and the control shaft 21 to connect the slider gear 26 and the control shaft 21 through the long hole 22a. One end of the locking pin 27 is inserted into a recess (not shown) formed in the control shaft 21, and the other end is inserted into a through hole 28 a formed in the bush 28.

  In such a variable valve mechanism 20, when the control shaft 21 is displaced in one direction along its axial direction, the slider gear 26 is also displaced in the axial direction in conjunction therewith. The helical splines 26a and 26b formed on the outer peripheral surface of the slider gear 26 mesh with the helical splines 23a and 24a formed on the inner peripheral surfaces of the input portion 23 and the output portion 24, respectively. When driven in the axial direction, the input unit 23 and the output unit 24 rotate in directions opposite to each other. As a result, the relative phase difference between the input unit 23 and the output unit 24 increases, and the rocking amount of the rocker arm 12 increases, so that the maximum lift amount VL of the intake valve 10 and the intake valve 10 as shown by the arrow X in FIG. The working angle INCAM increases synchronously, and the intake air amount of the internal combustion engine is increased. On the contrary, when the control shaft 21 is displaced in the other direction along the axial direction, the relative phase difference between the input unit 23 and the output unit 24 becomes small, and the rocking amount of the rocker arm 12 is reduced. As indicated by an arrow Y, the maximum lift amount VL and the working angle INCAM of the intake valve 10 decrease synchronously, and the intake air amount of the internal combustion engine is decreased.

  As shown in FIG. 2, a rotation / linear motion conversion mechanism 100 is connected to the base end portion (right side of FIG. 2) of the control shaft 21, and the rotation / linear motion conversion mechanism 100 is connected to an electric actuator. A certain electric motor 62 is connected. The electric motor 62 is connected to a drive circuit 63 that controls power supplied to the electric motor 62, and the drive circuit 63 is connected to the control device 200. The drive circuit 63 incorporates a detection circuit that detects the drive current CU of the electric motor 62.

  The rotation / linear motion conversion mechanism 100 is a mechanism that converts the rotational motion of the electric motor 62 into a linear motion in the axial direction of the control shaft 21. When the electric motor 62 is rotated forward or backward, the rotation is converted. It is converted into a reciprocating motion of the control shaft 21 by the rotation / linear motion converting mechanism 100.

  The electric motor 62 is provided with a position sensor 64. The position sensor 64 uses a magnetic change of a multipolar magnet that rotates integrally with the rotor of the electric motor 62 to output a signal corresponding to a change in the rotational phase of the rotor. Here, the control shaft 21 is reciprocated according to the rotation direction of the rotor of the electric motor 62. Therefore, the output signal of the position sensor 64 indicating the rotational phase change of the rotor indicates the amount of movement that is position information of the control shaft 21. Further, the maximum lift amount VL and the operating angle INCAM of the intake valve 10 are changed by the movement of the control shaft 21. Therefore, actual values of the maximum lift amount VL and the working angle INCAM of the intake valve 10 are detected based on the output signal of the position sensor 64.

  The control device 200 is a device that performs various controls of the internal combustion engine, and includes the position sensor 64, an accelerator sensor 70 that detects the operation amount of the accelerator pedal, and a crank angle sensor 71 that detects the rotational phase of the crankshaft. Various sensors for detecting the engine operating state are connected.

  In the present embodiment, for example, until the warm-up of the internal combustion engine is completed, the intake air amount is adjusted through the change of the valve characteristic of the intake valve 10 by the variable valve mechanism 20 and the adjustment of the opening degree of the throttle valve 4. The When the warm-up of the internal combustion engine is completed, the throttle valve 4 is basically fixed at an opening near the fully open position, and the intake air amount is adjusted by changing the valve characteristics of the intake valve 10 by the variable valve mechanism 20. Is called.

  The control device 200 calculates a required intake air amount based on the operating state detected by the various sensors, and obtains a target value of the working angle INCAM (hereinafter referred to as a target working angle INCAMp) so that the required intake air amount is obtained. ) Is set. Basically, the greater the amount of operation of the accelerator pedal, the greater the calculated required intake air amount and the larger the target operating angle INCAMp. The intake air amount is adjusted by controlling the drive of the electric motor 62 so that the operating angle INCAM matches the target operating angle INCAMp. In the drive control of the electric motor 62, the larger the deviation between the working angle INCAM and the target working angle INCAMp, the faster the valve characteristic of the intake valve 10 changes following the change in the operating state of the engine. The driving speed of the electric motor 62 is increased.

  Further, in the present embodiment, a pulse voltage is supplied to the electric motor 62, and so-called duty control is performed to change the duty ratio of the voltage supplied in a pulse shape to the electric motor 62. The rotational speed of the electric motor 62 is controlled by adjusting the supply power. Further, when the load on the electric motor 62 increases and the rotation speed of the electric motor 62 decreases, the decrease in the rotation speed is suppressed by increasing the supplied power by increasing the duty ratio. .

  By the way, when the load on the electric motor 62 increases, the power supplied to the electric motor 62 increases, and the temperature of the electric motor 62 (hereinafter referred to as motor temperature) may become excessively high.

  If the motor temperature becomes excessively high in this way, for example, the electrical resistance of the windings in the motor increases and the output torque decreases, the durability of the winding coating decreases due to thermal stress, and in some cases the windings The wire itself may burn out.

  As an example in which the load on the electric motor 62 increases, a cycle in which the amount of increase and decrease in the intake air amount through the change of the operating angle INCAM is short, for example, the operation amount of the accelerator pedal is frequently increased and decreased in a short cycle. The state that is frequently performed in is mentioned. In such a state, the driving direction of the electric motor 62 is also frequently switched in a short cycle. Therefore, when the driving direction of the electric motor 62 that has been rapidly driven in one direction (for example, in the direction in which the operating angle increases) is switched to another direction (for example, in the direction in which the operating angle decreases). It is necessary to cancel the relatively large inertial force in one direction that has been applied to the movable valve mechanism 20, the rotary / linear motion conversion mechanism 100, or the movable portion of the electric motor 62 so far. Therefore, the load on the electric motor 62 tends to be very large.

  Therefore, in this embodiment, when the load on the electric motor 62 increases, the drive speed of the electric motor 62 is limited in order to suppress overheating of the electric motor 62. By executing below, the influence of the execution of the restriction on the engine operating state is suppressed as much as possible.

  FIG. 5 shows the procedure for the process of limiting the drive speed of the electric motor 62, and FIG. 6 shows how the various values calculated by the limit process are changed. Note that the limiting process illustrated in FIG. 5 is repeatedly executed by the control device 200 at predetermined intervals, and the control device 200 that executes the limiting process constitutes the estimation unit and the limiting unit.

When this process is started, first, the drive current CU of the electric motor 62 is read (S100).
Next, it is determined whether or not the drive current CU is greater than or equal to the threshold value α (S110). The threshold value α is appropriately set to a value that can determine whether or not the electric motor 62 may be overheated due to an increase in load on the electric motor 62.

  When the drive current CU is greater than or equal to the threshold value α (S110: YES), the addition value I is added to the counter value C (S120), and when the drive current CU is less than the threshold value α (S110: NO) ), The subtraction value D is subtracted from the counter value C (S130). In this embodiment, “0” is set as the initial value of the counter value C, and the addition value I and the subtraction value D are fixed values, and “1” is set as the value. Other values may be set for each value. In other words, the processing in step S120 and step S130 starts addition / subtraction of the counter value C from the time when the drive current CU becomes equal to or greater than the threshold value α for the first time after the engine is started.

  The counter value C is increased when the load on the electric motor 62 is large and the motor temperature rises by the processing of Steps S110 to S130 (from time t1 to time t2 and after time t3 in FIG. 6). On the other hand, when the load on the electric motor 62 is small and the motor temperature decreases, the counter value C is decreased (time t2 to time t3 in FIG. 6). Thus, the counter value C reflects the increase / decrease history of the load on the electric motor 62. If the counter value C is large, the load on the electric motor 62 is averagely high, and the motor temperature is It can be determined that it is higher. Therefore, based on the counter value C, the state of the load causing heat generation of the electric motor 62 is appropriately estimated.

  Next, it is determined whether or not the updated counter value C is greater than or equal to the determination value CL (S140). The determination value CL is appropriately set to a value that can determine that the load on the electric motor 62 is high on average and the motor temperature is excessively high.

  When the counter value C is equal to or greater than the determination value CL (S140: YES, time t4 in FIG. 6), the load on the electric motor 62 is high on average, and the motor temperature may become excessively high. It is judged that there is. In this case, the drive speed of the electric motor 62 is limited by reducing the upper limit speed Smax of the electric motor 62 when the working angle INCAM is reduced (S150).

  This upper limit speed Smax is an upper limit value for restricting the maximum rotation speed (maximum drive speed) of the electric motor 62, and the maximum operation speed that is mechanically possible in the variable valve mechanism 20 and the rotation / linear motion conversion mechanism 100 is the upper limit speed Smax. This value is set because it is lower than the maximum rotation speed of the electric motor 62. Normally, the same basic value BA is set as the upper limit speed Smax when the working angle INCAM is reduced and as the upper limit speed Smax when the working angle INCAM is increased.

  In step S150, a process of changing the upper limit speed Smax of the electric motor 62 when the working angle INCAM is reduced from the basic value BA to the limit value LT is performed. The limit value LT is a fixed value lower than the basic value BA, and a maximum rotation speed capable of suppressing an increase in motor temperature is appropriately set.

  When the processing in step S150 is performed, it is next determined whether or not the intake air amount is adjusted by the throttle valve 4 (S160), and the intake air amount is adjusted by the throttle valve 4. If it is being performed (for example, before the completion of warm-up) (S160: YES), this process is temporarily terminated.

  On the other hand, when the adjustment of the intake air amount by the throttle valve 4 is not executed (for example, after completion of warm-up) (S160: NO), the opening reduction flag FC of the throttle valve 4 is changed from “OFF” to “ON”. (S170), the process is temporarily terminated. When the opening reduction flag FC is set to “ON”, an opening reduction process for reducing the opening of the throttle valve 4 is executed when the electric motor 62 is driven in a direction in which the working angle INCAM decreases. The

  This opening reduction process is performed for the following reason. That is, if the drive speed of the electric motor 62 when the operating angle INCAM is reduced is limited, the rate of reduction of the intake air amount is slowed down, so that the output reduction and the rotational speed reduction of the internal combustion engine are also slowed down. Here, when the adjustment of the intake air amount by the throttle valve 4 is being executed, the opening degree of the throttle valve 4 is also reduced when the operating angle INCAM is reduced. Therefore, in this case, even if the drive speed of the electric motor 62 is limited, the opening speed of the throttle valve 4 is reduced, so that a sufficient reduction speed of the intake air amount is ensured.

  On the other hand, when the adjustment of the intake air amount by the throttle valve 4 is not executed, in other words, when the intake air amount is adjusted by changing the operating angle INCAM by the variable valve mechanism 20, as described above. In addition, the rate of reduction of the intake air amount becomes slow. Thus, when the intake air amount is not adjusted by the throttle valve 4, the opening degree reducing process is executed, so that the valve characteristic of the intake valve 10 is reduced in the direction in which the intake air amount is reduced through the driving of the electric motor 62. Is changed, and when the drive speed of the electric motor 62 is limited, the opening of the throttle valve 4 is forcibly reduced. Therefore, the intake air amount is quickly reduced, and the output and rotation speed of the internal combustion engine are rapidly reduced. Therefore, in a vehicle including the control device 200 according to the present embodiment, even when the driving speed of the electric motor 62 when the working angle INCAM is reduced is limited, a feeling of deceleration of the vehicle is appropriately ensured. It should be noted that the amount of decrease in the opening of the throttle valve 4 at the time of execution of the opening decrease processing is appropriately determined so that at least the reduction rate of the intake air amount that is reduced by limiting the drive speed of the electric motor 62 can be compensated. Is set. For simplicity, the degree of opening reduction may be set so that the throttle valve 4 is fully closed.

  On the other hand, when it is determined in step S140 that the counter value C is less than the determination value CL (S140: NO), the basic speed is set as the upper limit speed Smax of the electric motor 62 when the operating angle INCAM is decreased. A value BA is set (S180). When the process of step S180 is performed, if the upper limit speed Smax of the electric motor 62 when the working angle INCAM is reduced is set to the limit value LT, the upper limit speed Smax is determined based on the limit value LT. The value BA is changed, and thereby the restriction on the driving speed of the electric motor 62 is released. If the upper limit speed Smax of the electric motor 62 when the working angle INCAM is reduced is set to the basic value BA when the process of step S180 is performed, the upper limit speed Smax is the basic value BA. Thus, the restriction on the driving speed of the electric motor 62 is not executed. And if the process of step S180 is performed, this process will be once complete | finished.

FIG. 7 shows the operation of the restriction process described above. FIG. 7 shows an aspect when it is determined that the load (counter value C) on the electric motor 62 exceeds the determination value CL.
As shown in FIG. 7, when the counter value C exceeds the determination value CL, the upper limit speed Smax of the electric motor 62 when the operating angle INCAM is reduced is changed from the reference value BA to the limit value LT. . Thus, with respect to the electric motor 62 whose driving direction is switched, only the driving speed of the electric motor 62 when driven in the direction in which the working angle INCAM is reduced, that is, the valve characteristic of the intake valve 10 in the direction in which the intake air amount is reduced. Only the driving speed of the electric motor 62 when the change is made is limited.

  In this way, when the electric motor 62 is driven in a direction in which the working angle INCAM is reduced by limiting the driving speed when the driving angle INCAM is reduced (upper limit speed Smax = limit value LT). The drive speed of the electric motor 62 at (time tb to td) is slower than that when not limited (upper limit speed Smax = reference value BA). Therefore, the heat generation of the electric motor 62 when it is driven in the direction in which the working angle INCAM is reduced is suppressed, and thereby the overheating of the electric motor 62 is suppressed.

  On the other hand, the driving speed when driven in the other direction, that is, the driving speed when the electric motor 62 is driven in the direction in which the working angle INCAM is increased is not limited (time ta to tb). For this reason, when the electric motor 62 is driven in a direction in which the working angle INCAM is decreased, the working angle INCAM can be quickly changed, whereby the engine output can be quickly increased.

  In this way, when the load on the electric motor 62 exceeds the determination value CL, the drive speed of the electric motor 62 is not simply limited, but only the drive speed when driven in one direction is limited. Yes. Therefore, when limiting the driving speed of the electric motor 62 in order to suppress overheating of the electric motor 62, the influence of the execution of the limitation on the engine operating state is suppressed as much as possible.

  Here, if the driving speed of the electric motor 62 when the working angle INCAM is driven to decrease is reduced, the reduction rate of the intake air amount through the reduction of the working angle INCAM becomes slow, so the output of the internal combustion engine decreases. And the rotation speed drop will be slow. However, in the present embodiment, there is an operating state in which the intake air amount is adjusted through the change of the working angle INCAM and the opening degree adjustment of the throttle valve 4. In this operating state, even if the drive speed of the electric motor 62 when the operating angle INCAM is changed in the direction in which the intake air amount is reduced, the intake air amount is reduced by adjusting the opening of the throttle valve 4. The amount is quickly reduced (time tb to time tc). Therefore, even if the driving speed of the electric motor 62 is decreased when the operating angle INCAM is decreased, the output and the rotational speed of the internal combustion engine can be quickly decreased. It can be secured appropriately.

  On the other hand, in this embodiment, the opening degree of the throttle valve 4 is fixed near the fully open position (shown by a two-dot chain line in FIG. 7), and the operating state in which the intake air amount is adjusted through the change of the working angle INCAM. Is also present. Therefore, when the operating angle INCAM is changed in such a driving state so that the intake air amount is reduced in a state where the driving speed of the electric motor 62 is limited, the opening degree of the throttle valve 4 is forcibly set. The above-described opening reduction process for reducing the time is performed (time tb to time tc). Therefore, even if the driving speed of the electric motor 62 when the operating angle INCAM is reduced in such a driving state is reduced, the suction is performed through the opening reduction of the throttle valve 4 by the opening reduction process. It is possible to secure a sufficient amount of air reduction. Therefore, even if the driving speed of the electric motor 62 is reduced in such an operating state, the output and the rotational speed of the internal combustion engine can be quickly reduced, and accordingly, a feeling of deceleration of the vehicle can be appropriately ensured. . As described above, in this embodiment, even if the driving speed of the electric motor 62 when the operating angle INCAM is decreased is reduced, the influence of the execution of such processing on the engine operating state is suppressed as much as possible.

As described above, according to the present embodiment, the following operational effects can be obtained.
(1) When the load on the electric motor 62 is estimated, and when the estimated load exceeds a preset determination value, the drive speed when the electric motor 62 is driven in one direction is driven in the other direction The driving speed when driving in one direction is limited so as to be slower than the driving speed. As described above, when the load on the electric motor 62 exceeds the determination value, the driving speed of the electric motor 62 is not simply limited, but only the driving speed when driven in one direction is limited. . Therefore, when limiting the drive speed of the electric motor 62 in order to suppress overheating of the electric motor 62, it is possible to suppress the influence of the execution of the limitation on the engine operating state as much as possible.

  (2) In the variable valve mechanism 20 in which the increase / decrease direction of the intake air amount through the change of the operating angle INCAM is switched by switching the drive direction of the electric motor 62, the variable valve mechanism 20 operates in the direction in which the intake air amount is decreased. The drive speed of the electric motor 62 when the angle INCAM is changed is limited. Therefore, the driving speed of the electric motor 62 when the operating angle INCAM is changed in the direction in which the intake air amount is increased is not limited, and thus the engine output can be increased quickly.

  (3) The working angle INCAM is changed in the direction in which the intake air amount is decreased when the intake air amount is being adjusted through the change of the working angle INCAM and the drive speed of the electric motor 62 is limited. When this is done, an opening reduction process for forcibly reducing the opening of the throttle valve 4 is performed. Therefore, even if the drive speed of the electric motor 62 when the working angle INCAM is changed in the direction in which the intake air amount is reduced, the output and rotation speed of the internal combustion engine can be quickly reduced. . Therefore, even in a vehicle provided with the control device according to the present embodiment, it is possible to suitably ensure a feeling of deceleration of the vehicle.

  Note that when the intake air amount is adjusted through the change of the working angle INCAM and the adjustment of the opening degree of the throttle valve 4, the electric motor 62 when the working angle INCAM is changed in the direction in which the intake air amount is reduced. Even if the drive speed is limited, the intake air amount is quickly reduced by adjusting the opening of the throttle valve 4. Accordingly, in this case as well, the output and rotation speed of the internal combustion engine can be quickly reduced, and thus a feeling of deceleration of the vehicle is suitably ensured.

  (4) The load is estimated based on a counter value C that is increased when the power supplied to the electric motor 62 is equal to or greater than a preset threshold value α, but is decreased when the threshold value α is not reached. . Therefore, it becomes possible to more appropriately estimate the state of the load that causes heat generation of the electric motor 62.

The above embodiment can be implemented with the following modifications.
Although the drive current CU is used as a value indicating the power supplied to the electric motor 62, the duty ratio may be used.

  When the electric motor 62 is driven in the direction in which the working angle INCAM is reduced and the driving speed is limited, the opening degree reduction process is performed. However, the driving speed is limited. Regardless of the non-execution, when the electric motor 62 is driven in a direction in which the working angle INCAM decreases, the opening degree reduction process may be performed.

  ・ When limiting the drive speed of the electric motor 62, the maximum rotation speed of the electric motor 62 is reduced, but in addition to this, the amount of change in the drive speed per unit time, that is, the acceleration is reduced. You may make it perform a restriction | limiting.

  The addition value I and the subtraction value D of the counter value C may be varied according to the deviation between the drive current CU and the threshold value α. For example, the larger the absolute value of the deviation between the drive current CU and the threshold value α, the larger the added value I or the subtracted value D may be set.

  Although the load on the electric motor 62 is estimated based on the counter value C, more simply, the load may be estimated based on the supplied power at that time. In carrying out this modification, for example, the processing of step S120 to step S140 is omitted in the restriction processing shown in FIG. Then, if an affirmative determination is made in step S110, the processing after step S150 may be executed, and if a negative determination is made in step S110, the processing after step S180 may be executed. Note that the threshold value α in the limiting process in this modification may be different from the threshold value α in the limiting process in the above embodiment.

  In the above embodiment, the limit value LT described above is set to a fixed value. In addition, the limit amount of the drive speed is variably set according to the estimated load size. More specifically, the limit amount is variable so that the drive speed decreases as the load increases. You may make it set. For example, when the counter value C is equal to or greater than the determination value CL, the limit value LT is variably set so that the limit value LT becomes lower as the counter value C increases, as shown in FIG. It may be. Further, when the load on the electric motor 62 is simply estimated based on the supply power at that time as in the above modification, as shown in FIG. 9, the limit value LT increases as the supply power increases. The limit value LT may be variably set so as to be a low value. In this case, the limit amount for limiting the driving speed of the electric motor 62 can be set more appropriately according to the heat generation state of the electric motor 62.

  The restriction process shown in FIG. 5 is performed only in an operating state in which the intake air amount is adjusted by changing the valve characteristics of the intake valve 10 by the variable valve mechanism 20 and adjusting the opening of the throttle valve 4. In the case of execution, the processing in step S160 and step S170 may be omitted. Further, the opening degree of the throttle valve 4 is fixed to an opening degree near the full opening, and only in the operation state in which the intake air amount is adjusted through the change of the valve characteristic of the intake valve 10 by the variable valve mechanism 20. When the restriction process shown in FIG. 5 is executed, the process of step S160 may be omitted.

  When it is determined that the load on the electric motor 62 is large, the driving speed when the electric motor 62 is driven in a direction in which the working angle INCAM is reduced is limited, but the direction in which the working angle INCAM is increased. Alternatively, the drive speed when the electric motor 62 is driven may be limited. Even in this case, it is possible to obtain at least the effect equivalent to the above (1).

The present invention can be similarly applied even when an electric linear motor that moves linearly or the like is used instead of the electric motor 62 that rotates.
Although the drive control of the variable valve mechanism 20 is performed based on the operating angle INCAM, it may be performed based on the maximum lift amount VL.

  The position sensor 64 is a magnetic sensor that detects a change in the rotational phase of the rotor of the electric motor 62 using a magnetic change. However, another sensor (for example, an optical sensor) may be used. Good.

  In the above embodiment, the valve characteristic of the intake valve 10 is changed by the variable valve mechanism 20, but when the valve characteristic of the exhaust valve 15 is changed or the valve characteristics of the intake valve 10 and the exhaust valve 15 are changed. The same applies to a change.

  The variable valve mechanism 20 described in the above embodiment is an example, and the valve characteristics of the engine valves such as the intake valve 10 and the exhaust valve 15 (for example, the opening timing, closing timing, valve opening period, or maximum lift in other configurations) The present invention can be similarly applied even to a variable valve mechanism that makes the amount or the like variable.

1 is a cross-sectional view illustrating a configuration of an intake / exhaust valve drive mechanism of an internal combustion engine to which the control device according to the present invention is embodied, to which the control device is applied. The top view which shows the arrangement structure of the intake / exhaust valve drive mechanism in the embodiment. The fracture | rupture perspective view of the variable valve mechanism in the embodiment. The graph which shows the change aspect about the valve characteristic of the intake valve in the embodiment. 6 is a flowchart showing a procedure of restriction processing in the embodiment. In the embodiment, a timing chart showing a change mode of a counter value according to a change in drive current, a change mode of an upper limit speed, and a setting mode of an opening reduction flag. The timing chart which shows the effect | action of the restriction | limiting process in the embodiment. The graph which shows the setting tendency of the limit value in the modification of the embodiment. The graph which shows the setting tendency of the limit value in the modification of the embodiment.

Explanation of symbols

  2 ... Cylinder head, 2a ... Intake port, 2b ... Exhaust port, 3 ... Intake passage, 4 ... Throttle valve, 5 ... Intake camshaft, 6 ... Intake camshaft, 7 ... Exhaust camshaft, 8 ... Exhaust cam, 10 Intake valve, 10a ... Retainer, 11 ... Valve spring, 12 ... Rocker arm, 12a ... Roller, 13 ... Rush adjuster, 14 ... Spring, 15 ... Exhaust valve, 15a ... Retainer, 16 ... Valve spring, 17 ... Rush adjuster, 18 ... Rocker arm, 18a ... Roller, 20 ... Variable valve mechanism, 21 ... Control shaft, 22 ... Support pipe, 22a ... Long hole, 23 ... Input part, 23a ... Helical spline, 23b ... Roller, 24 ... Output part, 24a ... Helical spline, 26 ... slider gear, 26a ... helical spline, 26b ... helicopter Ruspline, 27 ... locking pin, 28 ... bush, 28a ... through hole, 29 ... groove, 40 ... intake valve drive mechanism, 45 ... exhaust valve drive mechanism, 62 ... electric motor, 63 ... drive circuit, 64 ... position sensor , 70 ... Accelerator sensor, 71 ... Crank angle sensor, 100 ... Rotational linear motion conversion mechanism, 200 ... Control device.

Claims (7)

A variable valve mechanism that varies a valve characteristic of an engine valve of an internal combustion engine, and an electric actuator that drives the variable valve mechanism, and the drive direction of the electric actuator is switched, thereby changing the valve characteristic. In the control device of the variable valve mechanism that can switch the increase / decrease direction of the intake air amount,
Estimating means for estimating a load on the electric actuator;
When the load estimated by the estimating unit exceeds a predetermined determination value, the driving speed when the electric actuator is driven in one direction is slower than the driving speed when the electric actuator is driven in the other direction. And a limiting means for limiting the driving speed when driven in the one direction. 2. The variable valve mechanism according to claim 1, wherein the driving speed when driven in the one direction is a driving speed of the electric actuator when the valve characteristic is changed in a direction in which the intake air amount is reduced. Control device. 3. The control apparatus for a variable valve mechanism according to claim 2, wherein the intake air is adjusted in a state where the drive speed of the electric actuator is limited when the intake air amount is adjusted through the change of the valve characteristic. When the valve characteristic is changed in the direction in which the amount is reduced, an opening reduction process for reducing the opening of the throttle valve provided in the intake passage of the internal combustion engine is performed. Control device. The control device for a variable valve mechanism according to any one of claims 1 to 3, wherein the limiting means variably sets a limit amount of the driving speed according to the estimated magnitude of the load. An upper limit is set for the maximum drive speed of the electric actuator,
The variable valve mechanism according to any one of claims 1 to 4, wherein when the driving speed is limited by the limiting means, the upper limit value is set to a lower value than when the driving speed is not limited. Control device. The control device for a variable valve mechanism according to any one of claims 1 to 5, wherein the estimation means estimates the load based on power supplied to the electric actuator. The variable valve operating system according to claim 6, wherein the estimating means estimates the load based on a counter value that is increased when the supplied power is equal to or greater than a preset threshold value, but is decreased when the supplied power is less than the threshold value. Control device for the mechanism.

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