JP2018123716A - Valve timing adjustment device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a valve timing adjustment device of an internal combustion engine which can suppress the generation of noise.SOLUTION: A control device 53 of a valve timing adjustment device 50 comprises a drive control part 112 for calculating an indicated current value with respect to an electric motor 52 by performing feedback control using a target VVT phase and a VVT phase, and controlling the drive of the electric motor 52 on the basis of the indicated current value. When stopping an operation of an engine, and starting the operation of the engine, the drive control part 112 performs pressing processing for equalizing the target VVT phase and the most retardation phase to each other, and after that, on condition that the VVT phase is converged to the target VVT phase, holding the indicated current value at a constant value so as to press a protrusion of a drive rotating body to a stopper part of a driven rotating body.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a valve timing adjusting device for an internal combustion engine.

  As a valve timing adjusting device for an internal combustion engine, for example, as described in Patent Document 1, a variable mechanism that operates to adjust a relative rotational phase of a cam shaft with respect to an engine output shaft, and an electric motor that is a power source of the variable mechanism And are provided. The variable mechanism of such an apparatus includes a cylindrical driving rotating body that rotates in synchronization with the engine output shaft, and a driven rotating body that is disposed inside the driving rotating body and rotates integrally with the cam shaft. . A plurality of stopper portions projecting inward in the radial direction around the camshaft are provided on the inner peripheral side of the drive rotating body.

  The driven rotator is provided with protrusions positioned between the stopper portions adjacent to each other in the circumferential direction of the driven rotator. When the driven rotator rotates relative to the drive rotator relative to the advance side, the protrusion comes into contact with one of the stopper portions adjacent in the circumferential direction. The relative rotational phase at this time is referred to as “the most advanced angle phase”. Further, when the driven rotator rotates relatively to the retard side with respect to the drive rotator, the protrusion comes into contact with the other stopper portion of both the stopper portions adjacent in the circumferential direction. The relative rotational phase at this time is referred to as “most retarded phase”.

  In the valve timing adjusting device as described above, for example, the relative rotation phase can be changed by driving the electric motor using feedback control. In this case, the command current value for the electric motor is calculated by feedback control using the target value of the relative rotation phase and the actual relative rotation phase, and the drive of the electric motor is controlled based on the command current value. Thereby, the relative rotational phase can be adjusted according to the indicated current value.

Japanese Patent Laid-Open No. 2006-118107

  By the way, the target value of the relative rotational phase may be set to the most retarded phase. Thus, when the target value of the relative rotational phase is set to the most retarded phase, the actual relative rotational phase is set to the target by driving the electric motor based on the command current value calculated by the feedback control. The driven rotator rotates relatively to the retard side with respect to the drive rotator so as to reach the value. When the actual relative rotational phase reaches the target value, the protrusion of the driven rotator comes into contact with the stopper of the drive rotator.

  When the camshaft is rotating, cam torque that is torque resulting from the opening / closing operation of the engine valve is input to the camshaft, but the cam torque varies. The influence of such cam torque fluctuations on the control of the relative rotational phase increases as the engine speed decreases, as in the case of stopping the engine operation or starting the engine operation. When the engine rotational speed is low in this way, even if the actual relative rotational phase is held at the most retarded phase by the feedback control, the actual relative rotational phase may vibrate due to cam torque fluctuations. is there. In this case, there is a possibility that anomalous noise may be generated from the variable mechanism due to the repeated collision between the protrusion of the driven rotator and the stopper of the drive rotator and the separation of the protrusion from the stopper. There is.

  A valve timing adjusting device for an internal combustion engine for solving the above-mentioned problems is provided with a cylindrical driving rotating body that rotates in synchronization with an engine output shaft, and is disposed inside the driving rotating body, and opens and closes an intake valve. A driven rotating body that rotates integrally with the camshaft, an electric motor that drives the driven rotating body to change a relative rotational phase of the driven rotating body with respect to the drive rotating body, a target value of the relative rotational phase, and the relative rotational phase; A drive control unit that calculates a command current value for the electric motor by feedback control using the motor and controls the drive of the electric motor based on the command current value, and the drive rotor includes the camshaft. A plurality of stopper portions projecting inward in the radial direction centering on the cam shaft are provided, and the driven rotating body is provided between the stopper portions adjacent to each other in the circumferential direction centering on the cam shaft. A protrusion that is positioned, and one of the two stoppers adjacent in the circumferential direction contacts the stopper when the relative rotational phase is equal to the most advanced angle phase, and the other stopper The protrusion comes into contact with the portion when the relative rotational phase is equal to the most retarded phase. When the engine operation is stopped and the engine operation is started, the drive control unit sets the relative rotation phase target value equal to the most retarded angle phase and then sets the relative rotation phase target. On the condition that the relative rotational phase converges to a value, a pressing process for holding the indicated current value at a constant value is performed so as to press the protrusion against the other stopper.

  When the relative rotational phase is changed to the retard side, the amount of intake air charged into the cylinder of the internal combustion engine decreases, and the actual compression ratio of the cylinder decreases. Therefore, in the above configuration, when the engine operation is stopped and when the engine operation is started, the target value of the relative rotation phase is made equal to the most retarded angle phase, and the relative rotation phase is set to the target value (= the most retarded angle). (Phase). As a result, when the engine operation is stopped or when the engine operation is started, it is possible to suppress an excessive increase in the torque generated in the internal combustion engine, and to reduce the vibration generated in the internal combustion engine.

  In the above configuration, when the engine operation is stopped and when the engine operation is started, the relative rotation is set to the target value (= most retarded phase) of the relative rotation phase by controlling the electric motor using the feedback control. When the phase is converged, drive control of the electric motor is started by performing the pressing process. Then, the protrusion of the driven rotating body is pressed against the other stopper portion of the driving rotating body by a constant torque based on the driving of the electric motor. For this reason, even if the torque input from the outside to the camshaft (for example, cam torque resulting from the opening / closing operation of the intake valve) fluctuates, the protrusion is in contact with the stopper, that is, the relative rotation phase is the latest. It becomes easy to maintain a state equal to the angular phase. As a result, the occurrence of an event in which the collision between the protrusion and the stopper and the separation of the protrusion from the stopper are alternately suppressed, and the generation of abnormal noise from the valve timing adjusting device can be suppressed. It becomes like this.

The block diagram which shows the outline of an internal combustion engine provided with the valve timing adjustment apparatus of embodiment. Sectional drawing of the valve timing adjustment apparatus. FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 2. The flowchart which shows the process sequence for controlling the said relative rotation phase, when stopping an engine operation. The flowchart which shows the process sequence for controlling the said relative rotation phase, when restarting engine operation. (A), (b), (c) is a timing chart when engine operation is stopped. (A), (b), (c) is a timing chart in restarting engine operation.

Hereinafter, an embodiment of a valve timing adjusting device for an internal combustion engine will be described with reference to FIGS.
FIG. 1 illustrates an internal combustion engine 10 including a valve timing adjusting device 50 according to the present embodiment. As shown in FIG. 1, intake air is drawn into the combustion chamber 11 of the internal combustion engine 10 through the intake passage 13 when the intake valve 12 is opened. At this time, the fuel injected from the fuel injection valve 14 is also sucked into the combustion chamber 11. In the combustion chamber 11, the air-fuel mixture containing intake air and fuel is burned by being ignited by the spark plug 15. Then, the force generated by the combustion is transmitted to the crankshaft 18 as the engine output shaft through the piston 16 and the connecting rod 17, and the crankshaft 18 rotates. When the air-fuel mixture is combusted in the combustion chamber 11, the exhaust is discharged from the combustion chamber 11 to the exhaust passage 20 when the exhaust valve 19 is opened.

  The internal combustion engine 10 includes a cam shaft 21 that opens and closes the intake valve 12 and a cam shaft 22 that opens and closes the exhaust valve 19. The intake valve camshaft 21 is provided with a variable mechanism 51 for adjusting the opening / closing timing of the intake valve 12, that is, the valve timing. The variable mechanism 51 is one of the components of the valve timing adjusting device 50. Then, the rotational force of the crankshaft 18 is transmitted from the timing chain to the variable mechanism 51 and is transmitted to the camshaft 21 via the variable mechanism 51. Further, the rotational force of the crankshaft 18 is directly transmitted to the camshaft 22 for the exhaust valve via the timing chain. When the rotational force of the crankshaft 18 is transmitted to the camshafts 21 and 22, the valves 12 and 19 are opened and closed by the rotation of the cams 23 and 24 provided integrally with the camshafts 21 and 22. ing.

Next, the valve timing adjusting device 50 will be described with reference to FIGS.
As shown in FIGS. 1 and 2, the valve timing adjusting device 50 includes an electric motor 52 that is a power source of the variable mechanism 51, a control device 53 that controls driving of the electric motor 52, in addition to the variable mechanism 51 described above. It has. When the extending direction of the cam shaft 21 for the intake valve (the left-right direction in FIG. 2) is the axial direction F, the electric motor 52 is opposite to the cam shaft 21 across the variable mechanism 51 in the axial direction F (in FIG. 2). On the left). As the electric motor 52, a three-phase AC motor is employed.

  As shown in FIGS. 2 and 3, the variable mechanism 51 includes a drive rotator 61 that rotates in synchronization with the crankshaft 18, a driven rotator 62 that rotates integrally with the camshaft 21 for the intake valve, and an electric motor 52. And a torque transmission part 63 for transmitting the torque output from the motor to the driven rotor 62.

  The drive rotator 61 includes a cylindrical main body 71, a cylindrical housing 72 disposed on the electric motor 52 side (left side in FIG. 2) in the axial direction F of the main body 71, and electric drive in the axial direction F of the housing 72. And a cover member 73 disposed on the motor 52 side. The main body 71, the housing 72 and the cover member 73 are arranged coaxially with the output shaft of the electric motor 52. The housing 72 and the cover member 73 are fixed to the main body 71 by fastening members 74 such as bolts.

  On the outer peripheral side of the main body 71, a sprocket portion 711 over which the timing chain is bridged is provided. Therefore, when the crankshaft 18 is rotating, the main body 71, that is, the drive rotating body 61 rotates in the rotation direction CR that is the clockwise direction in FIG. As shown in FIG. 3, a plurality (four in this embodiment) of stopper portions 712 are provided on the inner peripheral side of the main body 71 so as to protrude inward in the radial direction around the cam shaft 21. Yes. Each of these stopper portions 712 is arranged along the circumferential direction around the cam shaft 21.

As shown in FIG. 2, a plurality of drive-side inner teeth 721 arranged along the circumferential direction protrude from the inner peripheral side of the housing 72.
As shown in FIG. 2, the driven rotator 62 is disposed inside the main body 71. The driven rotor 62 has a bottomed cylindrical shape so that the electric motor 52 side (left side in FIG. 2) in the axial direction F is opened and the cam shaft 21 side (right side in FIG. 2) in the axial direction F is closed. I am doing. The camshaft 21 is fixed to the bottom wall 621 of the driven rotor 62 by a bolt B.

  Further, as shown in FIG. 3, a protrusion 623 protruding outward in the radial direction is provided on the outer peripheral side of the side wall 622 of the driven rotor 62. The number of protrusions 623 is the same as the number of stopper portions 712. Each of the protrusions 623 is disposed between the stopper portions 712 adjacent to each other in the circumferential direction. The driven rotator 62 has a rotation phase in which the protrusion 623 abuts on one stopper 712 and rotation in which the protrusion 623 abuts the other stopper 712 among the stoppers 712 adjacent to each other in the circumferential direction. Relative rotation with respect to the drive rotator 61 is possible with respect to the phase.

In addition, a plurality of driven side internal teeth 624 arranged along the circumferential direction protrude from the inner peripheral side of the side wall 622 of the driven rotating body 62.
As shown in FIGS. 2 and 3, the torque transmission portion 63 is disposed inside the planetary gear 81 and the cylindrical planetary gear 81 disposed inside the drive rotator 61 and the driven rotator 62. A cylindrical planetary carrier 82 is provided. The planetary gear 81 has an outer peripheral surface that is eccentric with respect to the central axis L of the cam shaft 21.

  The planetary gear 81 has a portion facing the side wall 622 of the driven rotator 62 in the radial direction and a portion facing the housing 72 of the drive rotator 61 in the radial direction. In the planetary gear 81, a plurality of driven-side external teeth 811 that mesh with the driven-side internal teeth 624 are provided on the outer periphery of a portion that faces the side wall 622 of the driven rotating body 62 in the radial direction. . The number of driven side external teeth 811 is smaller than the number of driven side internal teeth 624. In addition, a plurality of drive-side external teeth 812 that mesh with the drive-side internal teeth 721 are provided on the outer periphery of a portion of the planetary gear 81 that faces the housing 72 in the radial direction. The number of driving side external teeth 812 is smaller than the number of driving side internal teeth 721.

  The planet carrier 82 is connected to the output shaft of the electric motor 52. The planet carrier 82 has an inner peripheral surface centered on the central axis L of the cam shaft 21 and an outer peripheral surface that is eccentric with respect to the central axis L. The planet carrier 82 is supported by the cover member 73 of the drive rotor 61 via the first bearing 64 and supported by the planetary gear 81 via the second bearing 65. Therefore, the planetary gear 81 can perform planetary motion by making the rotational speed of the planet carrier 82 different from the rotational speed of the drive rotor 61.

  When the planetary carrier 82 is rotating at the same speed as the drive rotator 61 in the clockwise direction in FIG. 3 by driving the electric motor 52, the planetary gear 81 does not perform planetary motion and the drive rotator 61. And the driven rotor 62 is rotated. Therefore, the relative rotation phase of the driven rotator 62 with respect to the drive rotator 61, that is, the relative rotation phase of the camshaft 21 with respect to the crankshaft 18 is maintained. Such a relative rotational phase is referred to as a “VVT phase θ”.

  On the other hand, when the electric motor 52 is driven, the planetary carrier 82 rotates in the clockwise direction in FIG. 3 at a lower speed than the driving rotating body 61, or the planetary carrier 82 rotates in the counterclockwise direction in FIG. The planetary gear 81 moves in a planetary motion. As a result, the VVT phase θ changes to the retard side.

  In addition, when the planetary carrier 82 rotates at a higher speed than the driving rotating body 61 in the clockwise direction in FIG. 3 by driving the electric motor 52, the planetary gear 81 performs planetary motion. As a result, the VVT phase θ changes to the advance side.

  As shown in FIG. 3, among the stopper portions 712 adjacent to each other in the circumferential direction, the protrusion 623 is opposite to the rotation direction CR of the drive rotor 61 (counterclockwise direction side in FIG. 3). The VVT phase θ when the protrusion 623 is in contact with the stopper portion 712 that is positioned is referred to as “most retarded angle phase θR”. In addition, among the stopper portions 712 adjacent to each other in the circumferential direction, the protrusion 623 corresponds to the stopper portion 712 that is located on the rotation direction CR side (clockwise direction in FIG. 3) of the drive rotating body 61 relative to the protrusion 623. The VVT phase θ when is in contact is referred to as “the most advanced angle phase θA”.

  As shown in FIG. 1, the control device 53 indicates the rotational speed of the crankshaft sensor 101 that outputs a pulse signal corresponding to the rotational speed of the crankshaft 18 and the camshaft 21 for the intake valve. A cam shaft sensor 102 that outputs a pulse signal corresponding to the cam rotation speed is electrically connected. Then, the control device 53 determines the VVT phase θ based on the engine rotational speed NE calculated based on the pulse signal from the crankshaft sensor 101 and the cam rotational speed NC calculated based on the pulse signal from the camshaft sensor 102. And the drive of the electric motor 52 is controlled based on the VVT phase θ.

The control device 53 includes a target setting unit 111 and a drive control unit 112 as functional units for adjusting the VVT phase θ.
Target setting unit 111 sets target VVT phase θTr, which is a target value of VVT phase θ, to a value corresponding to the engine operating state. In the present embodiment, when the engine operation is stopped and when the engine operation is started, the target setting unit 111 makes the target VVT phase θTr equal to the most retarded phase θR.

  The drive control unit 112 calculates an instruction current value Ivvt for the electric motor 52 by feedback control using the target VVT phase θTr and the VVT phase θ, and controls driving of the electric motor 52 based on the instruction current value Ivvt. Further, when the target VVT phase θTr is held at the most retarded angle phase θR as in the case of stopping the engine operation or starting the engine operation, the drive control is performed when a specified condition described later is satisfied. The unit 112 fixes the command current value Ivvt at a constant value, and holds the VVT phase θ at the most retarded phase θR by pressing the protrusion 623 against the stopper unit 712 with a constant torque output from the electric motor 52. Perform the pressing process.

  In the present embodiment, the drive of the electric motor 52 is controlled by vector control. Therefore, the indicated current value Ivvt is a command value of the q-axis current of vector control. When the electric motor 52 is driven, a current corresponding to the command current value Ivvt is input to each phase of the electric motor 52.

Next, with reference to FIG. 4, a processing procedure of control of the valve timing adjusting device 50 when stopping the engine operation will be described.
As shown in FIG. 4, first, in step S11, the target VVT phase θTr is set to a value equal to the most retarded angle phase θR. This process is performed by the target setting unit 111. Subsequently, in the next step S12, it is determined whether or not the VVT phase θ has converged to the target VVT phase θTr (= θR). This determination process is performed by the drive control unit 112. If the VVT phase θ has not yet converged to the target VVT phase θTr (step S12: NO), the process proceeds to the next step S13.

  In step S <b> 13, normal VVT phase control processing is performed by the drive control unit 112. For example, when the difference Δθ (= | θ−θTr |) between the VVT phase θ and the target VVT phase θTr is equal to or larger than a reference value, the proportional term X and the differential term Z of the feedback control are added to the target VVT phase θTr. The instruction target VVT phase θTrA is calculated by multiplying the sum (θTr + X + Z) by a shared gain. The command current value Ivvt is derived so as to be a value corresponding to the command target VVT phase θTrA, and the drive of the electric motor 52 is controlled based on the command current value Ivvt. On the other hand, when the difference Δθ is less than the reference value, the proportional term X and the integral term Y of the feedback control are added to the target VVT phase θTr, and the sum (θTr + X + Y) is multiplied by the shared gain to indicate Target VVT phase θTrA is calculated. The command current value Ivvt is derived so as to be a value corresponding to the command target VVT phase θTrA, and the drive of the electric motor 52 is controlled based on the command current value Ivvt. Then, the process proceeds to step S12 described above.

  On the other hand, when the VVT phase θ has converged to the target VVT phase θTr in step S12 (YES), the process proceeds to the next step S14. In step S14, the drive control unit 112 determines whether or not the engine rotational speed NE is equal to or lower than the determination rotational speed NETh1. The VVT phase θ is based on the engine rotational speed NE calculated based on the pulse signal output from the crankshaft sensor 101 and the cam rotational speed NC calculated based on the pulse signal output from the camshaft sensor 102. This is a calculated value. For this reason, when the actual engine speed decreases, the pulse interval in the pulse signal from each of the sensors 101 and 102 increases, and the calculation accuracy of the engine speed NE and the cam speed NC decreases. Further, when the actual engine speed is low, the speed fluctuation during one rotation of the crankshaft 18 is large. As described above, when the fluctuation of the engine rotational speed NE is large, the detection variation of the rotational position of the crankshaft 18 serving as a reference in calculating the VVT phase θ is large. Therefore, the variation in the rotational position of the cam 23 calculated based on the pulse signal output from the cam shaft sensor 102 increases, and as a result, the calculation accuracy of the VVT phase θ also decreases. Therefore, the determination rotational speed NETh1 is set to a value that can determine whether or not the calculation accuracy of the VVT phase θ is low. Therefore, when the engine rotational speed NE is equal to or lower than the determination rotational speed NETh1, it can be determined that the calculation accuracy of the VVT phase θ is low.

  In step S14, when the engine rotational speed NE is higher than the determined rotational speed NETh1 (NO), the process proceeds to step S13 described above. On the other hand, when the engine rotational speed NE is equal to or lower than the determined rotational speed NETh1 (step S14: YES), the process proceeds to the next step S15.

  In the next step S <b> 15, the pressing process described above is performed by the drive control unit 112. Then, in the next step S16, it is determined whether or not the engine rotational speed NE is equal to “0”, that is, whether or not the engine operation is stopped. If the engine speed NE is greater than “0” (step S16: NO), the engine operation has not been stopped yet, and the process proceeds to step S15 described above. On the other hand, when the engine speed NE is equal to “0” (step S16: YES), the engine operation is stopped, and thus the series of processes shown in FIG. 4 is ended.

Next, with reference to FIG. 5, a control processing procedure of the valve timing adjusting device 50 when the engine operation is restarted after the engine operation is stopped will be described.
As shown in FIG. 5, first, in step S21, the target VVT phase θTr is set to a value equal to the most retarded angle phase θR. This process is performed by the target setting unit 111. Subsequently, in the next step S <b> 22, the pressing process is performed by the drive control unit 112. In step S23, the drive control unit 112 determines whether or not the engine rotational speed NE is equal to or higher than the determination rotational speed NETh2. As described above, the lower the actual engine rotation speed, the lower the calculation accuracy of the VVT phase θ. Therefore, the determination rotational speed NETh2 is set to a value that can determine whether or not the calculation accuracy of the VVT phase θ is low. Therefore, when the engine rotational speed NE is equal to or lower than the determination rotational speed NETh2, it can be determined that the calculation accuracy of the VVT phase θ is low.

  In step S23, when the engine rotational speed NE is less than the determined rotational speed NETh2 (NO), the process proceeds to step S22 described above. On the other hand, when the engine rotational speed NE is equal to or higher than the determination rotational speed NETh2 (step S23: YES), the process proceeds to the next step S24.

  In step S24, the target setting unit 111 performs the target VVT phase θTr setting process. That is, the target VVT phase θTr is set to a value according to the engine operating state. Subsequently, in the next step S25, a normal VVT phase control process is performed by the drive control unit 112, as in step S13. Then, in the next step S26, it is determined whether or not the engine start has been completed. For example, when the internal combustion engine 10 is completely exploded, it can be determined that the engine operation has been completed. If the engine start has not yet been completed (step S26: NO), the process proceeds to step S24 described above. On the other hand, when the engine start has been completed (step S26: YES), the series of processes shown in FIG. 5 is terminated.

Next, with reference to FIG. 6, the operation when stopping the engine operation will be described together with effects.
As shown in FIGS. 6A, 6B, and 6C, when engine stop is requested at the first timing t11 during engine operation, the target VVT phase θTr is set to the most retarded phase θR. The Then, the command current value Ivvt is changed by the feedback control so that the VVT phase θ changes toward the most retarded phase θR. Then, at the second timing t12 when the VVT phase θ is changing toward the target VVT phase θTr (= θR), the engine speed NE starts to decrease.

  In this way, at the third timing t13 when the engine speed NE is decreasing, the VVT phase θ converges to the target VVT phase θTr (= θR). However, at this point in time, the engine speed NE is still higher than the determined speed NETh1, and therefore the pressing process is not yet performed. Under the situation where the engine rotational speed NE is higher than the determined rotational speed NETh1, the calculation accuracy of the VVT phase θ is not low. That is, the difference between the calculated VVT phase θ and the actual VVT phase is unlikely to occur. Further, when the engine speed NE is not so low, the influence of the cam torque variation on the control of the VVT phase θ is not so great. Therefore, by controlling the driving of the electric motor 52 by feedback control, it is possible to maintain a state where the VVT phase θ has converged to the target VVT phase θTr (= θR). Therefore, even when the VVT phase θ has converged to the target VVT phase θTr (= θR), the pressing process is not performed when the engine rotational speed NE is greater than the determined rotational speed NETh1.

  However, at the subsequent fourth timing t14, the engine rotational speed NE becomes equal to or lower than the determined rotational speed NETh1. Then, the calculation accuracy of the VVT phase θ becomes lower than before the fourth timing t14, and the influence of the fluctuation of the cam torque on the control of the VVT phase θ starts to increase. Therefore, driving of the electric motor 52 is controlled by performing the pressing process. That is, when stopping the engine operation, the target VVT phase θTr is made equal to the most retarded angle phase θR, the VVT phase θ is converged to the target VVT phase θTr, and the engine rotational speed NE is judged to be low. The pressing process is performed on the condition that both the rotational speed NETh <b> 1 and below are established. Then, the protrusion 623 of the driven rotator 62 is pressed by the stopper 712 of the drive rotator 61 with a certain amount of torque based on the drive of the electric motor 52.

  Here, when the engine rotational speed NE is equal to or lower than the determination rotational speed NETh1, the calculation accuracy of the VVT phase θ is low, so the VVT phase θ may be a value on the retard side with respect to the target VVT phase θTr. is there. If feedback control is performed in such a case, the drive of the electric motor 52 is controlled so that the VVT phase θ approaches the target VVT phase θTr, that is, the VVT phase θ is displaced to the advance side. As a result, the torque transmitted to the protrusion 623 by the drive of the electric motor 52 may vibrate, and the VVT phase θ may vibrate. Further, in the case where the feedback control is performed in such a state where the engine rotational speed NE is equal to or less than the determination rotational speed NETh1, the VVT phase θ may vibrate due to cam torque fluctuations.

  In this respect, in the present embodiment, by performing the pressing process, a certain amount of torque for pressing the protrusion 623 against the stopper 712 is input to the protrusion 623. For this reason, even when the calculation accuracy of the VVT phase θ is low and the cam torque varies, the state where the protrusion 623 is in contact with the stopper 712 can be maintained. Thereby, the occurrence of an event in which the collision between the protrusion 623 and the stopper 712 and the separation of the protrusion 623 from the stopper 712 are alternately repeated is suppressed. Therefore, it is possible to suppress the generation of abnormal noise from the variable mechanism 51 due to the repeated repetition of the collision and the separation.

Next, with reference to FIG. 7, the operation when the engine operation is restarted after the engine operation is stopped will be described together with effects.
As shown in FIGS. 7A, 7B, and 7C, when the restart of the engine operation is requested at the first timing t21, the target VVT phase θTr is set to the most retarded angle phase θR. . That is, when starting the engine operation, the target VVT phase θTr is made equal to the most retarded angle phase θR, the VVT phase θ is converged to the target VVT phase θTr, and the engine rotational speed NE is judged to be low. The pressing process is performed on the condition that both the rotational speed NETh <b> 2 and below are established.

  Then, the protrusion 623 of the driven rotator 62 is pressed by the stopper 712 of the drive rotator 61 with a certain amount of torque based on the drive of the electric motor 52. Therefore, even if the cam torque input to the camshaft 21 fluctuates or the calculation accuracy of the VVT phase θ is low, the state where the protrusion 623 is in contact with the stopper portion 712, that is, the VVT phase θ is the latest. It becomes easy to maintain a state equal to the angular phase θR. As a result, the occurrence of an event in which the collision between the protrusion 623 and the stopper 712 and the separation of the protrusion 623 from the stopper 712 are alternately repeated is suppressed. Therefore, it is possible to suppress the generation of abnormal noise from the variable mechanism 51 due to the repeated repetition of the collision and the separation.

  As described above, the engine speed NE starts to increase from the second timing t22 during the pressing process. When the engine rotational speed NE exceeds the determination rotational speed NETh2 at the third timing t23, the pressing process is terminated, and the drive of the electric motor 52 is controlled based on the command current value Ivvt calculated by the feedback control. Will come to be. That is, when the engine is started, if the engine rotational speed NE exceeds the determined rotational speed NETh2, it can be determined that the calculation accuracy of the VVT phase θ is not low, and the influence of cam torque variation on the control of the VVT phase θ is small. Therefore, the drive of the electric motor 52 is controlled by feedback control. Thereby, VVT phase (theta) can be made to track target VVT phase (theta) Tr.

Incidentally, when the drive of the electric motor 52 is controlled by feedback control under the condition where the target VVT phase θTr is held at the most retarded phase θR, the collision between the protrusion 623 and the stopper 712, and the stopper The phenomenon that the separation of the protrusion 623 from 712 is alternately repeated is likely to occur when the variable mechanism 51 having the following characteristics is employed.
The difference between the most retarded phase θR and the most advanced phase θA is large.
The VVT phase θ is likely to change with respect to changes in torque input from the outside, such as cam torque.

  Even in the valve timing adjusting device 50 including such a variable mechanism 51, the VVT phase θ is set to the target VVT phase under the situation where the target VVT phase θTr is held at the most retarded angle phase θR as in the present embodiment. By starting the pressing process when it converges to θTr, the separation of the protrusion 623 from the stopper 712 can be suppressed. Therefore, it is possible to suppress the generation of abnormal noise from the variable mechanism 51 when the engine is started or when the engine is stopped.

The above embodiment may be changed to another embodiment as described below.
In the case of stopping the engine operation, if the VVT phase θ is converged to the target VVT phase θTr, the pressing process is started even if the engine rotational speed NE is larger than the determination rotational speed NETh1. Also good.

  The determination rotational speed NETh2 may be a value equal to the determination rotational speed NETh1 or may be a value different from the determination rotational speed NETh1.

DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 12 ... Intake valve, 18 ... Crankshaft, 21 ... Cam shaft, 50 ... Valve timing adjusting device, 52 ... Electric motor, 61 ... Drive rotary body, 62 ... Driven rotary body, 623 ... Projection part, 712 ... stopper part, 112 ... drive control part.

Claims (1)

A cylindrical drive rotor that rotates in synchronization with the engine output shaft;
A driven rotator that is disposed inside the drive rotator and rotates integrally with a camshaft for opening and closing the intake valve;
An electric motor that is driven to change a relative rotational phase of the driven rotor relative to the drive rotor;
A drive control unit that calculates an instruction current value for the electric motor by feedback control using the target value of the relative rotation phase and the relative rotation phase, and controls driving of the electric motor based on the instruction current value; With
The drive rotator is provided with a plurality of stopper portions projecting inward in the radial direction centered on the cam shaft, and the driven rotator is adjacent to each other in the circumferential direction centered on the cam shaft. Protrusions located between each stopper are provided,
The protrusion comes into contact with one of the stopper portions adjacent in the circumferential direction when the relative rotational phase is equal to the most advanced phase, and the other rotational portion has the relative rotational phase. The protrusion comes into contact when the phase is equal to the most retarded phase,
When stopping the engine operation and starting the engine operation, the drive control unit equalizes the target value of the relative rotation phase to the most retarded angle phase and then sets the target value of the relative rotation phase. On the condition that the relative rotational phase has converged, a pressing process for holding the indicated current value at a constant value so as to press the protrusion against the other stopper is performed. Valve timing adjustment device.

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