JP4066366B2 - Variable valve timing control device for internal combustion engine - Google Patents

Description

  The present invention relates to a variable valve timing control device for an internal combustion engine that varies the valve timing of an intake valve or an exhaust valve of the internal combustion engine.

  In recent years, internal combustion engines mounted on vehicles are increasingly using variable valve timing devices that vary the valve timing of intake valves and exhaust valves for the purpose of improving output, reducing fuel consumption, and reducing exhaust emissions. . Currently, a variable valve timing device that is in practical use is a valve of an intake valve or an exhaust valve that is driven to open and close by a camshaft by driving a phase variable mechanism with hydraulic pressure to change the rotational phase of the camshaft with respect to the crankshaft. There are many things that change the timing. However, this hydraulically driven variable valve timing device has a drawback that the valve timing control accuracy is lowered due to insufficient hydraulic pressure or reduced responsiveness of hydraulic control during cold weather or engine start.

Therefore, for example, as described in Patent Document 1 (Japanese Patent Application Laid-Open No. 6-213021), the valve timing is determined by driving the phase variable mechanism with the driving force of the motor to change the rotational phase of the cam shaft relative to the crankshaft. A variable valve timing apparatus of a motor drive type that changes the pressure has been developed.
Japanese Patent Laid-Open No. 6-213021 (pages 5-6, etc.)

  However, the conventional motor-driven variable valve timing device has a configuration in which the entire motor rotates integrally with a pulley that is driven to rotate by a crankshaft, so that the inertia weight of the rotating system of the variable valve timing device increases. There is a drawback that the durability of the variable valve timing device is lowered. Moreover, in order to connect the rotating motor and the external electrical wiring, a sliding contact type connection structure using a brush or the like must be used, which also causes a decrease in durability. Furthermore, the conventional motor-driven variable valve timing apparatus has the disadvantages that the configuration is generally complicated and the cost is high.

  The present invention has been made in consideration of such circumstances. Accordingly, the object of the present invention is to provide valve timing by a motor drive system while satisfying the demand for improvement in durability and cost reduction of a variable valve timing device. It is an object of the present invention to provide a variable valve timing control device for an internal combustion engine that can be controlled and can improve valve timing control accuracy.

In order to achieve the above object, the variable valve timing device used in the invention according to claim 1 has a rotational speed that is 1/2 of the rotational speed of the crankshaft. The cam shaft phase is changed by adjusting the rotation speed of the motor with respect to the rotation speed ) . Specifically, as in claim 2, a first rotating member disposed concentrically with the camshaft and driven to rotate by the rotational driving force of the crankshaft, and a second rotating integrally with the camshaft. And a phase variable member that transmits the rotational force of the first rotating member to the second rotating member and changes the rotational phase of the second rotating member with respect to the first rotating member. A motor arranged concentrically with the camshaft to control the rotational phase of the phase variable member, and when the valve timing is not changed, the rotational speed of the motor matches the rotational speed of the first rotating member. by the variable phase member at a turning rate to match the rotational speed of the first rotary member, a rotational phase difference between the first rotary member and the second rotary member and the status quo Maintain the cam shaft phase When changing the timing is the rotational speed of the motor is varied with respect to the rotational speed of the first rotating member, changes the rotation speed of the phase changing member with respect to the rotational speed of said first rotary member Thus, the cam shaft phase is changed by changing the difference in rotational phase between the first rotating member and the second rotating member.

  In this configuration, since it is not necessary to rotate the entire motor, the inertia weight of the rotating system of the variable valve timing device can be reduced, and the motor and the external electric wiring are directly connected by a fixed connecting means. In general, the durability of the variable valve timing device can be improved. In addition, the configuration of the variable valve timing device is relatively simple, and the demand for cost reduction can be satisfied.

  Further, in the invention according to claim 1, the required valve timing change speed is calculated based on the deviation between the target valve timing and the actual valve timing, and the required rotation between the motor and the camshaft is calculated based on the required valve timing change speed. The speed difference is calculated, and the motor control value is calculated so that the rotational speed difference between the motor and the camshaft is controlled to the required rotational speed difference. In this way, the motor rotational speed can be accurately controlled in a feed-forward manner so that the rotational speed difference between the motor and the camshaft matches the required rotational speed difference. Can be controlled to the target valve timing, and the valve timing control accuracy can be improved.

  In this case, as a specific method for calculating the motor control value necessary for controlling the difference in rotational speed between the motor and the cam shaft to the required rotational speed difference, for example, as in claim 3, the rotation of the cam shaft The required motor rotational speed may be calculated based on the speed and the required rotational speed difference, and the motor control value may be calculated so as to control the rotational speed of the motor to the required motor rotational speed. Alternatively, as in claim 4, a basic control value for controlling the rotational speed of the motor to the same basic motor rotational speed as the rotational speed of the camshaft is calculated, and the rotational speed of the motor is calculated with respect to the basic motor rotational speed. Then, a change control value for changing the required rotational speed difference may be calculated, and the motor control value may be calculated based on the basic control value and the change control value. Whichever method is used, the motor control value necessary for controlling the difference in rotational speed between the motor and the camshaft to the required rotational speed difference can be accurately calculated.

  Further, as in claim 5, when the deviation between the target valve timing and the actual valve timing is less than or equal to a predetermined value, the motor control value is calculated so as to control the rotation speed of the motor to the same rotation speed as the rotation speed of the camshaft. You may make it do. In this way, when the actual valve timing is at or near the target valve timing, the actual valve timing can be stably maintained as it is.

  By the way, since the output torque of the motor is also consumed as a loss torque due to friction loss inside the variable valve timing device or drive loss on the camshaft side, the rotational speed difference between the motor and the camshaft is controlled to the required rotational speed difference. The motor control values (applied voltage value, duty value, etc.) required for this change depending on the drive loss inside the variable valve timing device or on the camshaft side. In addition, since a counter electromotive force is generated in the motor when the motor rotates, the motor control value required to control the difference in rotational speed between the motor and the camshaft to the required rotational speed difference also varies depending on the counter electromotive force of the motor. To do.

  In consideration of these circumstances, as in claim 6, friction loss inside the variable valve timing device or a parameter correlated therewith, drive loss on the camshaft side or parameter correlated therewith, motor reverse The motor control value may be calculated using at least one of the electromotive force or a parameter correlated therewith. In this way, the motor control value can be calculated taking into account changes in the drive loss inside the variable valve timing device and on the camshaft side, and changes in the back electromotive force of the motor, so friction loss and back electromotive force can be calculated. The motor control value necessary for controlling the difference in rotational speed between the motor and the camshaft to the required rotational speed difference can be accurately calculated without being affected by the above.

  In the variable valve timing device of the present invention, the valve timing change speed changes in accordance with the rotational speed difference between the motor and the camshaft. Therefore, the friction loss inside the variable valve timing device is caused by the rotational speed difference between the motor and the camshaft. Will change accordingly. Therefore, when using the friction loss parameter inside the variable valve timing device (friction loss or a parameter correlated therewith), the friction loss inside the variable valve timing device depends on the actual rotational speed difference between the motor and the camshaft. The parameter may be calculated, or the friction loss parameter inside the variable valve timing device may be calculated according to the required rotational speed difference between the motor and the camshaft as in claim 7. In this way, the friction loss parameter inside the variable valve timing device used for calculating the motor control value can be calculated in a feed-forward manner, and the responsiveness of the motor rotation control can be improved. As a result, the motor rotation speed can follow the cam shaft rotation speed with good response even under driving conditions where the engine rotation speed (cam shaft rotation speed) changes suddenly, such as during racing (when idling). And the valve timing control accuracy can be ensured.

  In addition, since the back electromotive force of the motor changes in accordance with the rotation speed of the motor, when the motor back electromotive force parameter (back electromotive force or a parameter correlated therewith) is used, the actual rotation speed of the motor The back electromotive force parameter of the motor may be calculated according to the motor speed. However, the motor according to the required motor rotational speed calculated based on the rotational speed of the camshaft and the required rotational speed difference as in claim 8. The back electromotive force parameter may be calculated. In this way, the back electromotive force parameter of the motor used for calculating the motor control value can be calculated in a feedforward manner, and the same effect as in the seventh aspect can be obtained.

  By the way, as shown in FIG. 12, when the rotational speed of the motor changes, the back electromotive force of the motor changes and the effective voltage (difference between the battery voltage and the back electromotive force) changes. Further, when the motor speed increases, the effective voltage decreases as the motor rotation speed increases. Conversely, when the motor speed increases, the effective voltage increases as the motor rotation speed increases.

  Therefore, as described in claim 9, the motor control value may be corrected based on the rotational speed of the motor and / or its increase / decrease state. In this way, even if the effective voltage changes depending on the rotational speed of the motor or its increase / decrease state, the motor control value can be corrected accordingly, and the appropriate voltage can be corrected without being affected by the change in the effective voltage. A motor control value can be calculated.

  The invention according to claim 9 is preferably applied to a system that calculates a duty value (energization rate) for duty-controlling the power supplied to the motor as the motor control value, as in claim 10. In duty control, the supply voltage to the motor is adjusted by adjusting the supply voltage duty value to adjust the supply voltage to the motor, but even if the duty value is the same, the effective voltage (battery voltage and back electromotive force and Change), the amplitude of the supply voltage pulse changes, so that the power supplied to the motor changes accordingly. Therefore, if the duty value is corrected based on the rotational speed of the motor and its increased / decreased state, the effective voltage changes depending on the rotational speed of the motor and its increased / decreased state, and the amplitude of the supply voltage pulse changes accordingly. The pulse width of the supply voltage can be corrected by correcting the value, and the change in the supply power due to the change in the amplitude of the supply voltage pulse can be compensated by correcting the pulse width of the supply voltage.

  Further, as in the eleventh aspect, a limit value may be provided for at least one of the change speed of the valve timing, the difference in rotation speed between the motor and the camshaft, and the rotation speed of the motor. In this way, it is possible to limit the change speed of the valve timing, the difference between the rotation speed of the motor and the camshaft, and the rotation speed of the motor with the limit values, so failure due to operation exceeding the guaranteed limit of the variable valve timing device. And damage can be avoided.

  Hereinafter, five embodiments 1 to 5 in which the present invention is applied to a variable valve timing control device for an intake valve will be described.

  A first embodiment of the present invention will be described with reference to FIGS. First, a schematic configuration of the entire system will be described with reference to FIG. The engine 11, which is an internal combustion engine, transmits power from the crankshaft 12 to the intake side camshaft 16 and the exhaust side camshaft 17 through the sprockets 14 and 15 by the timing chain 13 (or timing belt). It has become. A motor-driven variable valve timing device 18 is provided on the intake side camshaft 16 side. By varying the rotational phase (cam shaft phase) of the intake side camshaft 16 with respect to the crankshaft 12 by the variable valve timing device 18, the valve timing of an intake valve (not shown) driven to open and close by the intake side camshaft 16 is set. Can be changed.

  A cam angle sensor 19 that outputs a cam angle signal for each predetermined cam angle is attached to the outer peripheral side of the intake cam shaft 16. On the other hand, a crank angle sensor 20 that outputs a crank angle signal for each predetermined crank angle is attached to the outer peripheral side of the crankshaft 12.

  Next, a schematic configuration of the variable valve timing device 18 will be described with reference to FIG. The variable phase timing mechanism 21 of the variable valve timing device 18 includes an outer gear 22 (first rotating member) with internal teeth disposed concentrically with the intake camshaft 16, and concentrically on the inner peripheral side of the outer gear 22. The inner gear 23 with external teeth (second rotating member) is disposed, and the planetary gear 24 (phase variable member) is disposed between the outer gear 22 and the inner gear 23 and meshes with both. The outer gear 22 is provided so as to rotate integrally with the sprocket 14 that rotates in synchronization with the crankshaft 12, and the inner gear 23 is provided so as to rotate integrally with the intake side camshaft 16. Further, the planetary gear 24 functions to transmit the rotational force of the outer gear 22 to the inner gear 23 by rotating around the inner gear 23 in a state of meshing with the outer gear 22 and the inner gear 23, and also to play the inner gear 23. The rotational phase (cam shaft phase) of the inner gear 23 with respect to the outer gear 22 is adjusted by changing the turning speed (revolution speed) of the planetary gear 24 with respect to the rotational speed of 23 (the rotational speed of the intake camshaft 16). ing.

  On the other hand, the engine 11 is provided with a motor 26 for changing the turning speed of the planetary gear 24. The rotation shaft 27 of the motor 26 is arranged coaxially with the intake side cam shaft 16, the outer gear 22 and the inner gear 23, and the rotation shaft 27 of the motor 26 and the support shaft 25 of the planetary gear 24 are connected to extend in the radial direction. It is connected via a member 28. Thus, as the motor 26 rotates, the planetary gear 24 can turn (revolve) on the circular orbit on the outer periphery of the inner gear 23 while rotating (spinning) around the support shaft 25. Further, a motor rotation speed sensor 29 (see FIG. 1) for detecting the rotation speed RM of the motor 26 (the rotation speed of the rotation shaft 27) is attached to the motor 26.

  The variable valve timing device 18 matches the rotation speed RM of the motor 26 with the rotation speed RC of the intake camshaft 16 and matches the revolution speed of the planetary gear 24 with the rotation speed of the inner gear 23 (rotation speed of the outer gear 22). As a result, the current rotational phase difference between the outer gear 22 and the inner gear 23 is maintained, and the current valve timing (cam shaft phase) is maintained.

Then, in the case of advancing the valve timing of the intake valve controls the rotation speed RM of the motor 26 so that the rotational speed RM of the motor 26 becomes faster than the rotation speed RC of the intake camshaft 16, the planetary gears The revolution speed of 24 is made faster than the rotation speed of the inner gear 23. As a result, the rotational phase of the inner gear 23 with respect to the outer gear 22 is advanced, and the valve timing (cam shaft phase) is advanced.

On the other hand, in the case of retarding the valve timing of the intake valve controls the rotation speed RM of the motor 26 so that the rotational speed RM of the motor 26 is slower than the rotation speed RC of the intake camshaft 16, the planetary gears The revolution speed of 24 is made slower than the rotational speed of the inner gear 23. Thereby, the rotation phase of the inner gear 23 with respect to the outer gear 22 is retarded, and the valve timing is retarded.

  Outputs of the various sensors described above are input to an engine control circuit (hereinafter referred to as “ECU”) 30. The ECU 30 is mainly composed of a microcomputer, and executes various engine control programs stored in its ROM (storage medium), thereby injecting fuel from a fuel injection valve (not shown) according to the engine operating state. The amount and ignition timing of a spark plug (not shown) are controlled.

  Further, the ECU 30 executes a variable valve timing control program shown in FIG. 3 and a motor control value calculation program shown in FIG. 4 to be described later, thereby reducing the deviation D between the target valve timing VTtg of the intake valve and the actual valve timing VT. The required valve timing change speed Vreq is calculated so that the required rotational speed difference DMCreq between the motor 26 and the camshaft 16 is calculated based on the required valve timing change speed Vreq, and the rotational speed between the motor 26 and the camshaft 16 is calculated. A motor control value (for example, a motor applied voltage value) is calculated so as to control the difference DMC to the required rotational speed difference DMCreq. Thus, the rotation of the motor 26 is controlled so that the rotational speed difference DMC between the motor 26 and the camshaft 16 is controlled to the required rotational speed difference DMCreq, and the actual valve timing VT of the intake valve is controlled to the target valve timing VTtg. . Hereinafter, specific processing contents of each program will be described.

  The variable valve timing control program shown in FIG. 3 is executed at a predetermined cycle after, for example, an ignition switch (not shown) is turned on. When this program is started, first, at step 101, the target valve timing VTtg is calculated based on the engine operating state and the like, then the routine proceeds to step 102 where the crank angle signal output from the crank angle sensor 20 and the cam angle are calculated. The actual valve timing VT is calculated based on the cam angle signal output from the sensor 19.

  Each time the cam angle signal is output, the actual valve timing VTC when the cam angle signal is output is calculated based on the crank angle signal and the cam angle signal, and the motor rotational speed RM and the cam shaft are calculated at a predetermined calculation cycle. The valve timing after the cam angle signal is output by calculating the valve timing change amount per calculation cycle based on the difference from the rotational speed RC and calculating the valve timing change amount per calculation cycle after the cam angle signal is output. The change amount ΔVT may be obtained, and the final actual valve timing VT may be obtained by adding the valve timing change amount ΔVT after cam angle signal output to the actual valve timing VTC at the time of cam angle signal output.

  After calculating the actual valve timing VT, the process proceeds to step 103, where a deviation D between the target valve timing VTtg and the actual valve timing VT is calculated, and in the next step 104, the deviation D is reduced in accordance with the deviation D. The required valve timing change speed Vreq is calculated from a map or the like. The required valve timing change speed Vreq is, for example, a positive value when the valve timing change direction is on the advance side, and a negative value when the change direction is on the retard side. The processing in step 104 serves as a required valve timing change speed calculation means in the claims.

  Thereafter, the routine proceeds to step 105, where it is determined whether or not the speed limit Vs is set for the valve timing change speed. This speed limit Vs is, for example, a relatively slow valve that does not cause the gear mechanism (gears 22 to 24) to bite or be damaged even when a movable part for limiting the movable range of the phase variable mechanism 21 collides with the stopper part. (1) When the actual valve timing VT is within the speed limit range set near the most retarded position or near the most advanced position, (2) Valve timing reference position learning has been completed. If not, (3) the speed limit Vs is set, for example, when it is determined that the reference position learning is abnormal (reference position mislearning).

  If it is determined in step 105 that the speed limit Vs is set, the process proceeds to step 106, where it is determined whether or not the absolute value of the required valve timing change speed Vreq is larger than the speed limit Vs. As a result, if it is determined that the absolute value of the required valve timing change speed Vreq is larger than the limit speed Vs, the process proceeds to step 107, and after the absolute value of the required valve timing change speed Vreq is guarded with the limit speed Vs. , Go to Step 108.

  On the other hand, if it is determined in step 105 that the speed limit Vs is not set, or if it is determined in step 106 that the absolute value of the required valve timing change speed Vreq is equal to or lower than the speed limit Vs. Adopts the required valve timing change speed Vreq calculated according to the deviation D between the target valve timing VTtg and the actual valve timing VT, and proceeds to step 108.

In step 108, the required rotational speed difference DMCreq [rpm] between the motor 26 and the camshaft 16 is calculated by the following equation using the required valve timing change speed Vreq [° C. A / s].
DMCreq = Vreq × 60 × G / 720 ° C. A
Here, G is a reduction ratio of the phase variable mechanism 21 and is a ratio between the relative rotation amount of the motor 26 with respect to the cam shaft 16 and the valve timing change amount (cam shaft phase change amount). The processing of this step 108 serves as a required rotational speed difference calculation means in the claims.

After calculating the required rotational speed difference DMCreq, the routine proceeds to step 109, where the motor control value is calculated by executing the motor control value calculation program shown in FIG. The motor control value calculation program of FIG. 4 serves as a motor control value calculation means in the claims. When this program is started, first, at step 201, it is determined whether or not the deviation D between the target valve timing VTtg and the actual valve timing VT is equal to or smaller than a predetermined value. In step 202, the requested motor rotation speed RMreq is set to the camshaft rotation speed RC.
RMreq = RC

On the other hand, if it is determined in step 201 that the deviation D between the target valve timing VTtg and the actual valve timing VT is larger than a predetermined value, the process proceeds to step 203, where the requested motor rotational speed RMreq is set to the camshaft rotational speed. A value obtained by adding the required rotational speed difference DMCreq to RC is set.
RMreq = RC + DMCreq

  After the required motor rotation speed RMreq is set in step 202 or 203 as described above, the process proceeds to step 204, where the required motor rotation speed RMreq and the camshaft rotation speed are calculated using the map or formula of the required torque TAreq shown in FIG. A required torque TAreq corresponding to the difference from RC is calculated. This required torque TAreq is a net torque (torque that does not include the loss torque in the variable valve timing device 18 or the loss torque on the camshaft 16 side) required to revolve the planetary gear 24 at the required motor rotational speed RMreq. . The map of the required torque TAreq shown in FIG. 5 is set based on the change characteristic of the required torque TAreq with respect to the difference between the required motor rotational speed RMreq and the camshaft rotational speed RC.

  Thereafter, the process proceeds to step 205, and the loss torque TB on the camshaft 16 side corresponding to the camshaft rotational speed RC is calculated using the map or formula of the loss torque TB on the camshaft 16 side shown in FIG. The loss torque TB on the cam shaft 16 side is a torque consumed by the drive loss on the cam shaft 16 side. The map of the loss torque TB on the camshaft 16 side shown in FIG. 6 is set based on the change characteristic of the loss torque TB on the camshaft 16 side with respect to the camshaft rotational speed RC.

  Then, in the next step 206, using the map or formula of the loss torque TC inside the variable valve timing device 18 shown in FIG. 7, the rotational speed difference DMC between the motor 26 and the camshaft 16 (motor rotational speed RM and camshaft rotation). The loss torque TC inside the variable valve timing device 18 corresponding to the difference with the speed RC) is calculated. The loss torque TC inside the variable valve timing device 18 is a torque consumed by friction loss inside the variable valve timing device 18. The map of the loss torque TC inside the variable valve timing device 18 shown in FIG. 7 is set based on the change characteristic of the loss torque TC inside the variable valve timing device 18 with respect to the rotational speed difference DMC between the motor 26 and the camshaft 16. .

Thereafter, the routine proceeds to step 207, where the torque loss TB on the camshaft 16 side and the torque loss TC inside the variable valve timing device 18 are added to the required torque TAreq to control the motor rotational speed RM to the required motor rotational speed RMreq. The required motor torque TMreq necessary for the calculation is obtained.
TMreq = TAreq + TB + TC

  Thereafter, the process proceeds to step 208, where the required motor torque TMreq is converted into the required motor voltage VD using a map or the like. Then, the process proceeds to step 209, where the motor 26 uses the map or formula of the counter electromotive force E shown in FIG. A counter electromotive force E of the motor 26 corresponding to the rotational speed RM is calculated. The map of the counter electromotive force E of the motor 26 shown in FIG. 8 is set based on the change characteristic of the counter electromotive force E of the motor 26 with respect to the motor rotation speed RM.

Then, in the next step 210, the counter electromotive force E is added to the required motor voltage VD to obtain the motor applied voltage VM necessary for controlling the motor rotational speed RM to the required motor rotational speed RMreq.
VM = VD + E

  With the above processing, when the deviation D between the target valve timing VTtg and the actual valve timing VT becomes larger than a predetermined value, the required motor rotational speed RMreq is set to a value obtained by adding the required rotational speed difference DMCreq to the camshaft rotational speed RC. Then, the motor applied voltage VM necessary to control the motor rotational speed RM to the required motor rotational speed RMreq (= cam shaft rotational speed RC + required rotational speed difference DMCreq) is calculated. As a result, the rotational speed of the motor 26 is controlled in a feed-forward manner so that the rotational speed difference DMC between the motor 26 and the camshaft 16 matches the required rotational speed difference DMCreq, and the actual valve timing VT is set to the target valve timing VTtg. Change direction with good response.

  When the deviation D between the target valve timing VTtg and the actual valve timing VT becomes equal to or less than a predetermined value, the requested motor rotational speed RMreq is set to the camshaft rotational speed RC, and the motor rotational speed RM is set to the requested motor rotational speed. A motor applied voltage VM necessary for controlling to RMreq (= cam shaft rotational speed RC) is calculated. Thus, the rotation of the motor 26 is controlled so that the rotational speed difference DMC between the motor 26 and the camshaft 16 becomes 0, and the actual valve timing VT is stably held at or near the target valve timing VTtg. In this way, the actual valve timing can be accurately controlled to the target valve timing by the motor drive method, and the valve timing control accuracy can be improved.

  The variable valve timing device 18 according to the first embodiment includes an outer gear 22 that is concentrically arranged with the camshaft 16 and is driven to rotate by the rotational driving force of the crankshaft 12, and an inner gear that rotates integrally with the camshaft 16. 23, a planetary gear 24 that transmits the rotational force of the outer gear 22 to the inner gear 23 and changes the relative rotational phase between the two gears 22, 23, and the planetary gear 24 along a circular orbit concentric with the cam shaft 16. Therefore, it is not necessary to rotate the entire motor 26, the inertia weight of the rotating system of the variable valve timing device 18 can be reduced, and the motor 26 and the external electric power can be reduced. The wiring can be directly connected by a fixed connecting means, and overall, the durability of the variable valve timing device 18 can be improved. That. In addition, the configuration of the variable valve timing device 18 is relatively simple and can meet the demand for cost reduction.

  By the way, the output torque of the motor 26 is also consumed as loss torque due to friction loss inside the variable valve timing device 18 and drive loss on the camshaft 16 side, so the rotational speed difference DMC between the motor 26 and the camshaft 16 is requested to rotate. A motor control value (for example, a motor applied voltage) necessary for controlling the speed difference DMCreq varies depending on the drive loss inside the variable valve timing device 18 or the camshaft 16 side. Further, since the counter electromotive force is generated in the motor 26 when the motor 26 rotates, the motor control value necessary for controlling the rotational speed difference DMC between the motor 26 and the camshaft 16 to the required rotational speed difference DMCreq is It also changes depending on the counter electromotive force.

  Considering these circumstances, in the first embodiment, the loss torque TC consumed by the friction loss inside the variable valve timing device 18, the loss torque TB consumed by the drive loss on the camshaft 16 side, and the motor 26 Since the motor control value is calculated using the back electromotive force E, the change in the drive loss inside the variable valve timing device 18 and the cam shaft 16 and the change in the back electromotive force of the motor 26 are taken into consideration. The motor control value can be calculated, and the motor control necessary to control the rotational speed difference DMC between the motor 26 and the camshaft 16 to the required rotational speed difference DMCreq without being affected by friction loss, back electromotive force, etc. The value can be calculated with high accuracy.

  Further, in the first embodiment, the required valve timing change speed Vreq is limited by the limit speed Vs, so that failure or damage due to the sudden operation of the variable valve timing device 18 can be avoided.

  The motor control value calculation program shown in FIG. 9 executed in the second embodiment of the present invention has changed the processing in step 206 and step 209 in FIG. 4 described in the first embodiment to the processing in step 206a and step 209a, respectively. The processing of other steps is the same as in FIG.

  In the first embodiment, in step 206 of FIG. 4, the loss in the variable valve timing device 18 depends on the rotational speed difference DMC between the motor 26 and the camshaft 16 (difference between the motor rotational speed RM and the camshaft rotational speed RC). The torque TC is calculated, and in step 209, the counter electromotive force E of the motor 26 is calculated according to the motor rotational speed RM. In the second embodiment, in step 206a in FIG. The torque loss TC inside the variable valve timing device 18 is calculated according to the required rotational speed difference DMCreq of 16 (difference between the required motor rotational speed RMreq and the camshaft rotational speed RC), and in step 209a, the required motor rotational speed RMreq is set. Accordingly, the counter electromotive force E of the motor 26 is calculated.

  In this way, the loss torque TC inside the variable valve timing device 18 used for calculating the motor control value and the back electromotive force E of the motor 26 can be calculated in a feedforward manner, so that the response of the motor rotation control can be improved. Can be improved. As a result, even when the engine speed (cam shaft rotational speed RC) changes suddenly, such as during racing (when idling), the motor rotational speed RM follows the change in the cam shaft rotational speed RC with good response. The valve timing control accuracy can be ensured.

Next, Embodiment 3 of the present invention will be described with reference to FIGS.
As shown in FIG. 12, when the motor rotation speed RM changes, the back electromotive force of the motor 26 changes and the effective voltage (the difference between the battery voltage and the back electromotive force) changes. Further, the effective voltage differs between when the motor rotation speed RM is increased and when the motor is decelerated.

  In the third embodiment, by executing the motor control value calculation program shown in FIG. 10, the duty value for duty-controlling the power supplied to the motor 26 is calculated as the motor control value. In this duty control, by adjusting the duty value (energization rate) of the supply voltage, the supply voltage to the motor 26 is adjusted by adjusting the pulse width of the supply voltage. When the difference between the voltage and the counter electromotive force changes, the amplitude of the supply voltage pulse changes, and accordingly, the supply power to the motor 26 changes accordingly.

  Therefore, in the third embodiment, by executing the motor control value calculation program shown in FIG. 10, the duty value is corrected based on the motor rotation speed RM and the increase / decrease state thereof, and the motor rotation speed RM and the increase / decrease state thereof are corrected. The duty value is corrected in response to the change of the effective voltage.

  The motor control value calculation program shown in FIG. 10 is obtained by changing the processing of steps 208 to 210 in FIG. 4 described in the first embodiment to the processing of steps 208b to 210b. Same as 4.

  In this program, after calculating the required motor torque TMreq necessary for controlling the motor rotational speed RM to the required motor rotational speed RMreq in step 207, the process proceeds to step 208b, and the required motor torque TMreq is calculated as a required duty value by a map or the like. Convert to DDuty.

  Thereafter, the process proceeds to step 209b, where the motor rotation speed RM and its increase / decrease state are set using the map or formula of the effective voltage correction coefficient K at the time of motor acceleration and motor deceleration shown in FIGS. 11 (a) and 11 (b). A corresponding effective voltage correction coefficient K is calculated.

  As shown in FIG. 12, when the motor speed is increased, the effective voltage (difference between the battery voltage and the counter electromotive force) decreases as the motor rotation speed RM increases. At the time of motor deceleration, the effective voltage decreases as the motor rotation speed RM decreases. Therefore, the map of the effective voltage correction coefficient K at the time of motor acceleration shown in FIG. 11A increases the effective voltage correction coefficient K and increases the final duty value Duty as the motor rotation speed RM increases. In the map of the effective voltage correction coefficient K at the time of motor deceleration shown in FIG. 11B, the effective voltage correction coefficient K is increased and the final duty value Duty is increased as the motor rotation speed RM decreases. Is set.

After calculating the effective voltage correction coefficient K, the process proceeds to step 210b, and the final duty necessary to control the motor rotational speed RM to the required motor rotational speed RMreq by correcting the required duty value DDDuty with the effective voltage correction coefficient K by the following equation. A duty value Duty is obtained.
Duty = DD Duty × K

  In the third embodiment described above, the duty value is corrected in accordance with the motor rotation speed RM and its increase / decrease state. Therefore, the effective voltage varies depending on the motor rotation speed RM and its increase / decrease state, and the amplitude of the supply voltage pulse. The pulse width of the supply voltage can be corrected by correcting the duty value in response to the change in the supply voltage, and the change in the supply power due to the change in the amplitude of the supply voltage pulse is compensated by the correction of the pulse width of the supply voltage. Can do. As a result, stable motor rotation control can be performed without being affected by the effective voltage that changes depending on the motor rotation speed RM or its increase / decrease state.

  In the first embodiment, the required motor speed RMreq is obtained by adding the required speed difference DMCreq to the camshaft speed RC, and the motor control value is calculated so as to control the motor speed RM to the required motor speed RMreq. In the fourth embodiment of the present invention shown in FIG. 13, the basic control value for controlling the motor rotation speed RM to the same basic motor rotation speed RMbase as the camshaft rotation speed RC is calculated, and the motor rotation speed is calculated. A change control value for changing RM by a required rotation speed difference DMCreq with respect to the basic motor rotation speed RMbase is calculated, and a motor control value is calculated based on the basic control value and the change control value.

  In the motor control value calculation program of FIG. 13 executed in the fourth embodiment, first, at step 301, it is determined whether or not the deviation D between the target valve timing VTtg and the actual valve timing VT is equal to or less than a predetermined value. If D is equal to or smaller than a predetermined value, the process proceeds to step 302, and after resetting all of the required torque TAreq, loss torque change amount ΔTB, loss torque TC, and back electromotive force change amount ΔE described later to “0”, the process proceeds to step 307. .

  On the other hand, if it is determined in step 301 that the deviation D between the target valve timing VTtg and the actual valve timing VT is greater than a predetermined value, the process proceeds to step 303 and a map or formula of the required torque TAreq shown in FIG. After calculating the required torque TAreq according to the required rotational speed difference DMCreq (difference between the required motor rotational speed RMreq and the camshaft rotational speed RC), the process proceeds to step 304 and during transition (change in the camshaft rotational speed RC) ), The loss torque change amount ΔTB on the camshaft 16 side corresponding to the camshaft rotation speed change amount ΔRC is calculated using the map or formula of the loss torque TB on the camshaft 16 side shown in FIG.

  Thereafter, the process proceeds to step 305, where a rotational speed difference DMC between the motor 26 and the camshaft 16 (motor rotational speed RM and camshaft rotation) is calculated using a map or formula of the loss torque TC inside the variable valve timing device 18 shown in FIG. After calculating the loss torque TC in the variable valve timing device 18 according to the difference DMC with respect to the speed RC), the process proceeds to step 306, where the motor 26 is used to calculate the motor back electromotive force E shown in FIG. A back electromotive force change amount ΔE of the motor 26 corresponding to the rotation speed change amount ΔRM (motor rotation speed RM−basic motor rotation speed RMbase) is calculated.

  The required torque TAreq, the loss torque change amount ΔTB on the camshaft 16 side, the loss torque TC inside the variable valve timing device 18 and the back electromotive force change amount ΔE of the motor 26 are converted into the motor rotation speed RM as the basic motor rotation speed RMbase (= This corresponds to a change control value for changing the required rotational speed difference DMCreq with respect to the camshaft rotational speed RC).

  Thereafter, the process proceeds to step 307, and the loss torque TB on the camshaft 16 side corresponding to the camshaft rotational speed RC is calculated using the map or formula of the loss torque TB on the camshaft 16 side shown in FIG. Proceeding to 308, the basic back electromotive force Ebase of the motor 26 corresponding to the basic motor rotational speed RMbase (= cam shaft rotational speed RC) is calculated using the map or formula of the back electromotive force E of the motor 26 shown in FIG. .

  These torque loss TB on the camshaft 16 side and the basic counter electromotive force Ebase of the motor 26 correspond to basic control values for controlling the motor rotation speed RM to the basic motor rotation speed RMbase (= camshaft rotation speed RC).

Then, in the next step 309, the torque loss TB on the camshaft 16 side, the loss torque change amount ΔTB, and the loss torque TC inside the variable valve timing device 18 are added to the required torque TAreq, and the motor rotational speed RM is determined as the required motor. A required motor torque TMreq necessary to control the rotational speed RMreq is obtained.
TMreq = TAreq + TB + ΔTB + TC

Thereafter, the process proceeds to step 310, where the required motor torque TMreq is converted into the required motor voltage VD using a map or the like. Then, the process proceeds to step 311 where the basic counter electromotive force Ebase and the counter electromotive force variation ΔE are added to the requested motor voltage VD. Then, the motor applied voltage VM required to control the motor rotational speed RM to the required motor rotational speed RMreq is obtained.
VM = VD + Ebase + ΔE

  By the above processing, when the deviation D between the target valve timing VTtg and the actual valve timing VT becomes larger than a predetermined value, the motor rotation speed RM is controlled to the basic motor rotation speed RMbase (= cam shaft rotation speed RC). Based on the basic control values (TAreq, ΔTB, TC, ΔE) and the change control values (TB, Ebase) for changing the motor rotational speed RM by the required rotational speed difference DMCreq with respect to the basic motor rotational speed RMbase. The motor applied voltage VM is calculated. As a result, the rotational speed of the motor 26 is controlled in a feed-forward manner so that the rotational speed difference DMC between the motor 26 and the camshaft 16 matches the required rotational speed difference DMCreq, and the actual valve timing VT is set to the target valve timing VTtg. Change direction with good response.

  When the deviation D between the target valve timing VTtg and the actual valve timing VT becomes a predetermined value or less, it is necessary to control the motor rotation speed RM to the basic motor rotation speed RMbase (= cam shaft rotation speed RC). The motor applied voltage VM is calculated. As a result, the rotational speed of the motor 26 is controlled so that the rotational speed difference DMC between the motor 26 and the camshaft 16 is zero, and the actual valve timing VT is stably held at or near the target valve timing VTtg. Even in this case, the actual valve timing can be accurately controlled to the target valve timing by the motor drive system, and the valve timing control accuracy can be improved.

  The motor control value calculation program shown in FIG. 14 executed in the fifth embodiment of the present invention has changed the processing in step 305 and step 306 in FIG. 13 described in the fourth embodiment to processing in step 305a and step 306a, respectively. The processing of other steps is the same as in FIG.

  In the fourth embodiment, in step 305 in FIG. 13, the internal loss of the variable valve timing device 18 according to the rotational speed difference DMC between the motor 26 and the camshaft 16 (difference between the motor rotational speed RM and the camshaft rotational speed RC). The torque TC is calculated, and in the next step 306, the back electromotive force change amount ΔE of the motor 26 is calculated according to the motor rotation speed change amount ΔRM (motor rotation speed RM−basic motor rotation speed RMbase). In the fifth embodiment, in step 305a of FIG. 14, the variable valve timing device 18 has an internal structure corresponding to the required rotational speed difference DMCreq (the difference between the required motor rotational speed RMreq and the cam shaft rotational speed RC) between the motor 26 and the camshaft 16. Loss torque TC is calculated, and in the next step 306a, required motor rotation speed change amount ΔRMreq (required motor rotation speed RMreq−basic motor rotation) Calculating a counter electromotive force variation ΔE of the motor 26 in accordance with the degree RMbase).

  In this way, the loss torque TC in the variable valve timing device 18 used for calculating the motor control value and the back electromotive force variation ΔE of the motor 26 can be calculated in a feed-forward manner. Thus, the same effects as those of the second embodiment can be obtained.

  In the fourth and fifth embodiments, the motor applied voltage is calculated as the motor control value. However, the duty value may be calculated as the motor control value, and in this case, as in the third embodiment. In addition, the duty value may be corrected based on the motor rotation speed and its increase / decrease state.

  In each of the first to fifth embodiments, a limit value (limit speed Vs) is provided for the valve timing change speed. However, the rotation speed difference between the motor 26 and the cam shaft 16 and the motor rotation speed are limited. A limit value may be provided. Further, these limit values may be changed in accordance with the engine operating state (for example, engine rotation speed, cooling water temperature, intake air amount, load, etc.).

  Further, based on the convergence state of the valve timing and the valve timing change speed with respect to the target value, the control parameters used for calculating the motor control value or the motor control value (request torque TAreq, loss torque TB on the camshaft 16 side, variable valve timing device) 18, the internal torque loss TC, the back electromotive force E of the motor 26, the effective voltage correction coefficient K, etc.) may be corrected, and the correction result may be learned. Further, based on the correction result, a map or a mathematical expression used for calculating each control parameter may be corrected.

  Further, the present invention is not limited to the variable valve timing control device for the intake valve, but may be applied to the variable valve timing control device for the exhaust valve. Further, the phase variable mechanism of the variable valve timing device 18 is not limited to the one using the planetary gear mechanism as in the present embodiment, and other types of phase variable mechanisms may be used. Any motor-driven variable valve timing device that varies the valve timing by changing the speed with respect to the rotational speed of the cam shaft may be used.

It is a schematic block diagram of the whole control system in Example 1 of this invention. It is a schematic block diagram of a variable valve timing apparatus. 3 is a flowchart illustrating a flow of processing of a variable valve timing control program according to the first embodiment. 3 is a flowchart illustrating a flow of processing of a motor control value calculation program according to the first embodiment. It is a figure which shows notionally the map of request | requirement torque TAreq. It is a figure which shows notionally the map of the loss torque TB by the side of a cam shaft. It is a figure which shows notionally the map of the loss torque TC inside a variable valve timing apparatus. It is a figure which shows notionally the map of the counter electromotive force E of a motor. It is a flowchart which shows a part of process flow of the motor control value calculation program of Example 2. 12 is a flowchart illustrating a part of a process flow of a motor control value calculation program according to a third embodiment. (A) is a figure which shows notionally the map of the effective voltage correction coefficient K at the time of motor acceleration, (b) is a figure which shows notionally the map of the effective voltage correction coefficient K at the time of motor deceleration. It is a figure which shows the relationship between a motor rotational speed and its increase / decrease state, and an effective voltage. 10 is a flowchart illustrating a flow of processing of a motor control value calculation program according to a fourth embodiment. 12 is a flowchart illustrating a part of a process flow of a motor control value calculation program according to a fifth embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Crankshaft, 16 ... Intake side camshaft, 17 ... Exhaust camshaft, 18 ... Variable valve timing device, 19 ... Cam angle sensor, 20 ... Crank angle sensor, 21 ... Phase variable mechanism , 22 ... outer gear (first rotating member), 23 ... inner gear (second rotating member), 24 ... planetary gear (phase variable member), 26 ... motor, 29 ... motor rotational speed sensor, 30 ... ECU (request valve) Timing change speed calculation means, required rotation speed difference calculation means, motor control value calculation means)

Claims (11)

A variable valve timing device that changes a valve timing of an intake valve or an exhaust valve driven to open and close by a camshaft by changing a rotational phase of a camshaft with respect to a crankshaft of an internal combustion engine (hereinafter referred to as "camshaft phase"). In what to control
The variable valve timing device is configured to change the camshaft phase by adjusting the rotation speed of a motor with respect to a rotation speed that is 1/2 of the rotation speed of the crankshaft ,
A required valve timing change speed calculating means for calculating a required valve timing change speed based on a deviation between the target valve timing and the actual valve timing;
A required rotational speed difference calculating means for calculating a required rotational speed difference between the motor and the camshaft based on the required valve timing change speed;
Variable valve timing control for an internal combustion engine, comprising: motor control value calculating means for calculating a motor control value so as to control a difference in rotational speed between the motor and the camshaft to the required rotational speed difference apparatus. The variable valve timing device includes a first rotating member that is arranged concentrically with the camshaft and is rotationally driven by a rotational driving force of the crankshaft, and a second rotating member that rotates integrally with the camshaft. A phase variable member that transmits a rotational force of the first rotating member to the second rotating member and changes a rotational phase of the second rotating member with respect to the first rotating member, and the phase variable member A motor arranged concentrically with the camshaft so as to control the rotational phase of the motor, and when the valve timing is not changed, the rotational speed of the motor is made to coincide with the rotational speed of the first rotating member. , By maintaining the rotational phase difference between the first rotating member and the second rotating member at present, by matching the turning speed of the phase variable member with the rotating speed of the first rotating member , Cam shaft position Was status quo, the time of changing the valve timing, the rotational speed of the motor is varied with respect to the rotational speed of the first rotary member, wherein the phase variable member said first rotary member turning speed of The cam shaft phase is changed by changing a difference in rotational phase between the first rotating member and the second rotating member by changing the rotational speed of the cam shaft. The variable valve timing control device for an internal combustion engine according to claim 1.   The motor control value calculating means calculates a required motor rotational speed based on the rotational speed of the cam shaft and the required rotational speed difference, and controls the motor to control the rotational speed of the motor to the required motor rotational speed. The variable valve timing control device for an internal combustion engine according to claim 1 or 2, wherein a control value is calculated.   The motor control value calculation means calculates a basic control value for controlling the rotation speed of the motor to the same basic motor rotation speed as the rotation speed of the camshaft, and converts the rotation speed of the motor to the basic motor rotation speed. 3. A change control value for changing the difference between the required rotational speeds with respect to the motor is calculated, and the motor control value is calculated based on the basic control value and the change control value. A variable valve timing control device for an internal combustion engine according to claim 1.   The motor control value calculating means controls the motor control so as to control the rotation speed of the motor to the same rotation speed as the rotation speed of the camshaft when a deviation between a target valve timing and an actual valve timing is a predetermined value or less. The variable valve timing control device for an internal combustion engine according to any one of claims 1 to 4, wherein a value is calculated.   The motor control value calculation means includes a friction loss inside the variable valve timing device or a parameter correlated therewith, a drive loss on the camshaft side or a parameter correlated therewith, a back electromotive force of the motor, or this 6. The variable valve timing control device for an internal combustion engine according to claim 1, wherein the motor control value is calculated using at least one of parameters correlated with each other.   The internal combustion engine according to claim 6, wherein the motor control value calculation means calculates a friction loss in the variable valve timing device or a parameter correlated therewith according to the required rotational speed difference. Variable valve timing control device.   The motor control value calculation means calculates a back electromotive force of the motor or a parameter correlated therewith according to a requested motor rotation speed calculated based on the rotation speed of the cam shaft and the difference between the requested rotation speeds. The variable valve timing control device for an internal combustion engine according to claim 6 or 7,   9. The variable valve for an internal combustion engine according to claim 1, wherein the motor control value calculation means corrects the motor control value based on a rotation speed of the motor and / or an increase / decrease state thereof. Timing control device.   10. The variable valve timing control apparatus for an internal combustion engine according to claim 9, wherein the motor control value calculation means calculates a duty value for performing duty control on power supplied to the motor as the motor control value.   11. A limit value is provided for at least one of a change speed of the valve timing, a difference in rotation speed between the motor and the camshaft, and a rotation speed of the motor. The variable valve timing control device for an internal combustion engine according to any one of the above.

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