JP2012241539A - Variable valve gear for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable valve gear for an internal combustion engine capable of suppressing continuation of a valve timing unstable state for a long period and achieving an effect of the suppression with a simple constitution.SOLUTION: This variable valve gear includes: a valve timing variable mechanism for changing valve timing; an oil control valve for controlling a supply mode of lubricating oil to the advance-angle chamber and the retard-angle chamber; and a control device for controlling the supply mode of the lubricating oil of the oil control valve. The variable valve gear has a holding mode for at least holding the lubricating oil in the advance-angle chamber and holding the lubricating oil in the retard-angle chamber as the supply mode of the lubricating oil. A time for holding the supply mode of the lubricating oil of the oil control valve in the holding mode is specified as a holding time, and when the holding time is prescribed time or more, the supply mode of the lubricating oil of the oil control valve is changed to a mode other than the holding mode.

Description

  The present invention relates to a variable valve mechanism that changes a valve timing by changing a rotation phase of an output rotator with respect to an input rotator, and an oil passage change mechanism that controls a supply mode of lubricating oil to an advance chamber and a retard chamber. And a control device for controlling the valve timing by controlling the supply mode of the lubricating oil of the oil passage changing mechanism.

As the variable valve device, for example, as described in Patent Document 1, a device including a variable valve mechanism, an oil passage changing mechanism, and a control device is known.
In this type of variable valve operating apparatus, when a command to hold the valve timing is output to the variable valve operating mechanism, the lubricating oil supply mode of the oil path changing mechanism is set to the holding mode. However, since the hydraulic oil leaks from the clearances of the parts constituting the variable valve mechanism, the valve timing varies.

  The variable valve mechanism of Patent Document 1 is provided with vibration suppression means as a mechanism for suppressing fluctuations in valve timing when there is a request to maintain valve timing.

JP 2010-53856 A

According to the variable valve mechanism of Patent Document 1, fluctuations in valve timing are suppressed. However, since the variable valve mechanism is provided with vibration suppressing means, the configuration of the variable valve mechanism becomes complicated.
The present invention has been made in view of such a situation, and the object thereof is to suppress a state in which the valve timing is unstable from being continued for a long period of time, and to suppress the same with a simple configuration. It is an object of the present invention to provide a variable valve operating apparatus for an internal combustion engine that can achieve both.

In the following, means for achieving the above object and its effects are described.
The present invention includes a variable valve mechanism that changes a valve timing by changing a rotation phase of an output rotating body with respect to an input rotating body according to a supply mode of lubricating oil to an advance chamber and a retard chamber, and the advance chamber and the delay chamber. An internal combustion engine comprising: an oil passage changing mechanism that controls a supply mode of lubricating oil to a corner chamber; and a control device that controls valve timing by controlling the supply mode of the lubricating oil of the oil passage changing mechanism. In the variable valve device, the oil passage changing mechanism has a holding mode for holding at least the advance chamber lubricating oil and holding the retard chamber lubricating oil, as the supply mode of the lubricating oil of the oil passage changing mechanism, and changing the oil passage When the holding time of the mechanism's lubricating oil supply mode is the holding time, and the holding time is a predetermined time or longer, the lubricating oil supply mode of the oil path changing mechanism is changed to a mode other than the holding mode. And it is required to.

  In the holding mode, the lubricating oil is not supplied to the variable valve mechanism. On the other hand, in the variable valve mechanism, the internal lubricating oil leaks from the clearance of the parts. For this reason, if the holding mode is maintained for a predetermined time or more, the valve timing becomes unstable. In the said invention, it is suppressed that holding time becomes more than predetermined time. For this reason, it is suppressed that the state where valve timing becomes unstable continues for a long period of time. Further, since this effect is obtained by controlling the oil passage changing mechanism, the structure of the variable valve mechanism becomes simpler than the variable valve mechanism having the conventional structure.

The schematic diagram which shows typically the structure of an internal combustion engine about one Embodiment of this invention. (A) is sectional drawing which shows the cross-section of the valve timing variable mechanism of the same embodiment, (b) is sectional drawing which shows the cross-sectional structure which follows the AA line of (a). Sectional drawing which shows the structure of the oil control valve of the embodiment typically. Sectional drawing which shows operation | movement of the oil control valve of the embodiment. Sectional drawing which shows operation | movement of the oil control valve of the embodiment. The graph which shows the relationship between the duty, the opening area of each port, the displacement speed | rate of valve timing, and an opening degree about the oil control valve of the embodiment. The flowchart which shows the procedure of "valve timing control processing" about the variable valve apparatus of the embodiment. The flowchart which shows the procedure of "variation suppression control" about the variable valve apparatus of the embodiment. The graph which shows the relationship between a target phase angle, an actual phase angle, and a duty about the variable valve apparatus of the embodiment.

An embodiment of the present invention will be described with reference to FIGS.
FIG. 1 shows the overall configuration of the internal combustion engine.
The internal combustion engine 1 includes an engine body 10 including a cylinder block 11, a cylinder head 12, and an oil pan 13, a variable valve operating device 20 provided on the cylinder head 12, and a lubrication device 50 that supplies lubricating oil to the engine body 10 and the like. And a control device 70 for comprehensively controlling these devices.

  The variable valve operating apparatus 20 includes an intake valve 21 and an exhaust valve 23 that open and close the combustion chamber 14, an intake camshaft 22 and an exhaust camshaft 24 that push down these valves, and a valve timing variable mechanism that changes the valve timing of the intake valve 21. 30B and a variable valve timing mechanism 30A for changing the valve timing of the exhaust valve 23. The variable valve timing mechanism 30A on the exhaust side is provided with a phase locking mechanism 40 that maintains the exhaust valve timing VTA at a specific phase angle. In the following description, the valve timing of the exhaust valve 23 is “exhaust valve timing VTA”, and the valve timing of the intake valve 21 is “intake valve timing VTB”.

  The lubricating device 50 includes an oil pump 52 that discharges the lubricating oil from the oil pan 13, a lubricating oil passage 51 that supplies the lubricating oil discharged from the oil pump 52 to each part of the internal combustion engine 1, and lubricating oil for various mechanisms. Are provided with three oil control valves for controlling the supply mode.

  The first oil control valve 53 (hereinafter referred to as “first OCV 53”) controls the supply mode of the lubricating oil to the variable valve timing mechanism 30A on the exhaust side. The second oil control valve 54 (hereinafter referred to as “second OCV 54”) controls the supply mode of the lubricating oil to the intake side valve timing varying mechanism 30B. The third oil control valve 55 (hereinafter, “third OCV 55”) controls the supply mode of the lubricating oil to the phase locking mechanism 40.

  The control device 70 includes an electronic control device 71 that performs various arithmetic processes for controlling the internal combustion engine 1, and various sensors including a crank position sensor 72, an exhaust cam position sensor 73A, and an intake cam position sensor 73B. It has. The crank position sensor 72 outputs a signal corresponding to the rotation angle of the crankshaft 15 to the electronic control unit 71. The exhaust cam position sensor 73 </ b> A outputs a signal corresponding to the rotation angle of the exhaust cam shaft 24 to the electronic control unit 71. The intake cam position sensor 73B outputs a signal corresponding to the rotation angle of the intake camshaft 22 to the electronic control unit 71.

  The electronic control unit 71 calculates the following parameters for use in various controls. That is, based on the output signal from the crank position sensor 72, a calculation value corresponding to the rotation angle of the crankshaft 15 (hereinafter referred to as “crank angle signal CA”) is calculated.

  Further, a calculation value corresponding to the rotation angle of the exhaust camshaft 24 (hereinafter, “exhaust cam angle signal DA”) is calculated based on an output signal from the exhaust cam position sensor 73A. Based on the output signal from the intake cam position sensor 73B, a calculated value corresponding to the rotation angle of the intake camshaft 22 (hereinafter referred to as “intake cam angle signal DB”) is calculated. Based on the crank angle signal CA and the exhaust cam angle signal DA, a calculated value (hereinafter, “actual phase angle VTR”) corresponding to the exhaust valve timing VTA is calculated. A calculated value corresponding to the intake valve timing VTB is calculated based on the crank angle signal CA and the intake cam angle signal DB.

The control performed by the electronic control unit 71 includes valve timing control for changing the exhaust valve timing VTA and the intake valve timing VTB.
In the valve timing control, the exhaust valve timing VTA and the intake valve timing VTB are independently set to the most advanced valve timing (hereinafter, “most advanced angle VTmax”) and the most retarded valve based on the engine operating state. The timing is changed (hereinafter, “the most retarded angle VTmin”).

With reference to FIG. 2, the configuration of the variable valve timing mechanism 30A on the exhaust side will be described.
An arrow X in the figure indicates the rotation direction X of the exhaust camshaft 24. Note that the configuration of the intake-side variable valve timing mechanism 30B is the same as the configuration of the exhaust-side variable valve timing mechanism 30A, and a description thereof will be omitted.

  The variable valve timing mechanism 30A includes a housing rotor 31 that rotates in synchronization with the crankshaft 15, a vane rotor 35 that rotates in synchronization with the exhaust camshaft 24, and an assist spring 35A that applies force to the vane rotor 35 in the rotational direction X. The phase fixing mechanism 40 that fixes the vane rotor 35 to the housing rotor 31 is provided.

  The housing rotor 31 includes a sprocket 33 connected to the crankshaft 15 via a timing chain, a housing body 32 that is assembled inside the sprocket 33 and rotates integrally with the sprocket 33, and a cover that is attached to the housing body 32. 34. The housing body 32 is provided with three partition walls 31A that protrude toward the rotation axis (exhaust camshaft 24) of the housing rotor 31 in the radial direction.

  The vane rotor 35 is fixed to an end portion of the exhaust camshaft 24 and is disposed in a space in the housing main body 32. The vane rotor 35 is provided with three vanes 36 projecting between adjacent partition walls 31 </ b> A of the housing body 32. Each vane 36 partitions a vane storage chamber 37 formed between the partition walls 31 </ b> A into an advance chamber 38 and a retard chamber 39.

  The advance chamber 38 is located behind the vane 36 in the vane storage chamber 37 in the rotational direction X of the exhaust camshaft 24. The retard chamber 39 is located in the vane storage chamber 37 in front of the vane 36 in the rotational direction X of the exhaust camshaft 24.

  The rotational phase of the vane rotor 35 relative to the housing rotor 31 is determined by the rotational phase when the rotational phase of the vane rotor 35 is at the foremost side in the rotational direction X (hereinafter referred to as “the most advanced rotational phase”) and the rotational phase of the vane rotor 35. It changes between the rotational phases at the most rearward side of X (hereinafter, “the most retarded rotational phase”). The most advanced angle rotation phase corresponds to the most advanced angle VTmax as the exhaust valve timing VTA. The most retarded rotation phase corresponds to the most retarded angle VTmin as the exhaust valve timing VTA.

  The assist spring 35A applies a force to the housing rotor 31 in the direction of rotating the vane rotor 35 toward the advance side from the most retarded rotation phase to the most advanced rotation phase. The magnitude of this force is set to such a magnitude that the vane rotor 35 rotates to the most advanced rotational phase when the hydraulic pressure is not applied to the valve timing variable mechanism 30A.

The operation of the variable valve timing mechanism 30A will be described.
The supply of the lubricating oil to the advance chamber 38 and the discharge of the lubricant from the retard chamber 39 cause the advance chamber 38 to expand and the retard chamber 39 to contract so that the vane rotor 35 advances relative to the housing rotor 31. It rotates in the corner side, that is, in the rotation direction X. As a result, the exhaust valve timing VTA changes to the advance side.

  Due to the discharge of the lubricating oil from the advance chamber 38 and the supply of the lubricant oil to the retard chamber 39, the retard chamber 39 expands and the advance chamber 38 contracts, so that the vane rotor 35 is retarded relative to the housing rotor 31. It rotates in the direction opposite to the corner side, that is, the rotation direction X. As a result, the exhaust valve timing VTA changes to the retard side.

The structure of the first OCV 53 will be described with reference to FIG.
Note that the structure of the second OCV 54 is the same as the structure of the first OCV 53, and a description thereof will be omitted.

The first OCV 53 includes a sleeve 61 provided with a plurality of ports, and a spool 62 that moves within the sleeve 61.
The sleeve 61 is formed with an advance port 61A connected to the oil passage leading to the advance chamber 38 and a retard port 61B connected to the oil passage leading to the retard chamber 39. These ports are formed in the order of an advance port 61A and a retard port 61B along the axial direction of the sleeve 61. In addition to the above-mentioned ports, the sleeve 61 includes a supply port 61C connected to the lubricating oil supply oil path, an advance discharge port 61D for discharging the lubricant from the advance chamber 38, and a delay port. A retard discharge port 61E for discharging the lubricating oil from the corner chamber 39 is formed.

The spool 62 is provided with two valve bodies, that is, an advance valve 62A and a retard valve 62B.
The advance valve 62A is provided corresponding to the advance port 61A, and changes the opening area of the advance port 61A. The retard valve 62B is provided corresponding to the retard port 61B, and changes the opening area of the retard port 61B.

Next, the dimensional relationship of each valve body will be described.
In the following description, in each port and each valve body, a dimension in the same direction as the moving direction of the spool 62 is defined as a width dimension. The direction from the advance port 61A to the retard port 61B is the right direction, and the opposite direction is the left direction.

  The width dimension of the advance valve 62A is larger than the width dimension of the advance port 61A. The width dimension of the retard valve 62B is larger than the width dimension of the retard port 61B. A distance DX1 between the intermediate position in the width direction of the advance valve 62A and the intermediate position in the width direction of the retard valve 62B, and between the intermediate position in the width direction of the advance port 61A and the intermediate position in the width direction of the retard port 61B. When compared with the distance DX2, the former is larger than the latter.

Next, a contact portion (hereinafter referred to as “overlap”) between the valve body and the sleeve 61 near the port will be described.
Regarding the distance in the width direction of the contact portion where the advance valve 62A and the sleeve 61 are in contact with each other in the vicinity of the advance port 61A, the width direction distance on the supply port 61C side is defined as an advance supply overlap LAx, and on the advance discharge port 61D side. The distance in the width direction is defined as an advance discharge overlap LAy.

  Regarding the distance in the width direction of the contact portion where the retard valve 62B and the sleeve 61 contact in the vicinity of the retard port 61B, the distance in the width direction on the supply port 61C side is defined as a retard supply overlap LBx, and on the retard discharge port 61E side. The distance in the width direction is set as a retard discharge overlap LBy.

As shown in FIG. 3, the spool 62 is placed in the sleeve 61 so that the intermediate position between the advance valve 62A and the retard valve 62B matches the intermediate position between the advance port 61A and the retard port 61B. When arranged with respect to the above, the overlap has the following relationship.
The advance angle supply overlap LAx is smaller than the advance angle discharge overlap LAy.
The retard supply overlap LBx is smaller than the retard discharge overlap LBy.
The advance angle supply overlap LAx and the retard angle supply overlap LBx are equal.
The advance discharge overlap LAy and the retard discharge overlap LBy are equal.
That is, the relationship (LAx = LBx) <(LAy = LBy) is established.

With the above configuration, the following effects are achieved.
The distance DRs between the right end of the advance valve 62A and the right end of the retard valve 62B is larger than the distance DRp between the right end of the advance port 61A and the right end of the retard port 61B. This is because when the right end of the retard valve 62B and the right end of the retard port 61B coincide with each other due to the movement of the spool 62, the right end of the advance valve 62A does not coincide with the advance port 61A, and the advance port 61A. Indicates that the advance port 61A and the supply port 61C communicate with each other (see FIG. 4B).

  Similarly, the distance DLs between the left end of the advance valve 62A and the left end of the retard valve 62B is larger than the distance DLp between the left end of the advance port 61A and the left end of the retard port 61B. This is because when the left end of the advance valve 62A coincides with the left end of the advance port 61A due to the movement of the spool 62, the left end does not coincide with the left end of the retard valve 62B and the retard port 61B, and the retard port 61B. Indicates that the retard port 61B and the supply port 61C communicate with each other (see FIG. 5A).

Next, the supply mode of the first OCV 53 lubricating oil will be described.
The operation mode of the first OCV 53 is divided into five modes: an advance angle mode MA, a first quasi-holding mode MC1, a holding mode MC, a second quasi-holding mode MC2, and a retarding angle mode MB.

  In the advance angle mode MA, the lubricant is supplied to the advance chamber 38 and is discharged from the retard chamber 39. The vane rotor 35 rotates forward with respect to the housing rotor 31. That is, this mode corresponds to the advance angle of the exhaust valve timing VTA.

  In the first quasi-holding mode MC1, lubricating oil is supplied to the advance chamber 38 and the retard port 61B is closed. In this mode, since the retard chamber 39 is sealed, the rotational phase of the vane rotor 35 is maintained with respect to the housing rotor 31. That is, it corresponds to maintenance of the exhaust valve timing VTA.

  The holding mode MC closes the advance port 61A and closes the retard port 61B. The rotational phase between the vane rotor 35 and the housing rotor 31 is maintained. That is, this mode corresponds to maintaining the exhaust valve timing VTA.

  In the second quasi-holding mode MC2, the lubricating oil is supplied to the retard chamber 39 and the advance port 61A is closed. In this mode, since the advance chamber 38 is sealed, the vane rotor 35 is maintained with respect to the housing rotor 31. This mode corresponds to maintaining the exhaust valve timing VTA.

  In the retard mode MB, the lubricant is supplied to the retard chamber 39 and is discharged from the advance chamber 38. The vane rotor 35 rotates toward the retard side with respect to the housing rotor 31. That is, this mode corresponds to the retard angle of the exhaust valve timing VTA.

With reference to FIG. 4 and FIG. 5, the relationship between the movement of the spool 62 with respect to the sleeve 61 and the supply mode (operation mode) of the first OCV 53 will be described.
In the following description, the opening area of the advance port 61A in the first communication state where the advance port 61A and the supply port 61C communicate with each other is referred to as an opening area on the supply side. The opening area of the advance port 61A in the second communication state where the advance port 61A and the advance discharge port 61D communicate with each other is defined as an opening area on the discharge side. The opening area of the retardation port 61B in the third communication state where the retardation port 61B and the supply port 61C communicate with each other is defined as the opening area on the supply side. The opening area of the retard port 61B in the fourth communication state in which the retard port 61B and the retard discharge port 61E communicate with each other is defined as an opening area on the discharge side.

  The spool 62 moves in the axial direction according to the duty input to the first OCV 53. As the duty increases, the spool 62 moves from the advance port 61A toward the retard port 61B.

  The position when the spool 62 moves to the most advanced port 61A side is the leftmost position. The position when the spool 62 moves rightward from the leftmost position and the right end of the retard valve 62B coincides with the right end of the retard port 61B is defined as a first intermediate position. Furthermore, the position when the spool 62 moves to the right and the right end of the advance valve 62A coincides with the right end of the advance port 61A is defined as a second intermediate position. Further, the position when the spool 62 moves rightward and the left end of the retard valve 62B coincides with the left end of the retard port 61B is defined as a third intermediate position. Further, the position when the spool 62 moves to the right and the left end of the advance valve 62A coincides with the left end of the advance port 61A is defined as a fourth intermediate position. Further, the position when the spool 62 moves to the right and moves to the most advanced angle port 61A side is the rightmost position.

FIG. 4A shows a state where the spool 62 is in the first position with respect to the sleeve 61.
The first position indicates a range between the leftmost position and the first intermediate position. The first position corresponds to the advance angle mode MA.

  At this time, the opening area on the supply side of the advance port 61A is larger than “0”, and the opening area on the discharge side of the retard port 61B is larger than “0”. Due to the communication state between the ports, the lubricating oil is supplied to the advance chamber 38 and the lubricating oil in the retard chamber 39 is discharged.

FIG. 4B shows a state where the spool 62 is in the second position with respect to the sleeve 61.
The second position indicates a range between the first intermediate position and the second intermediate position. The second position corresponds to the first quasi-holding mode MC1.

  At this time, the opening area on the supply side of the advance port 61A is larger than “0”, and the opening area of the retard port 61B is “0”. Due to the communication state between the ports, the lubricating oil is supplied to the advance chamber 38, while the retard chamber 39 is sealed.

FIG. 4C shows a state where the spool 62 is in the third position with respect to the sleeve 61.
The third position indicates a range between the second intermediate position and the third intermediate position. The third position corresponds to the holding mode MC.

  At this time, the opening area of the advance port 61A is “0”, and the opening area of the retard port 61B is “0”. Due to the communication state between the ports, both the advance chamber 38 and the retard chamber 39 are sealed.

FIG. 5A shows the spool 62 in the fourth position with respect to the sleeve 61.
The fourth position indicates a range between the third intermediate position and the fourth intermediate position. The fourth position corresponds to the second quasi-holding mode MC2.

  At this time, the opening area on the supply side of the retard port 61B is larger than “0”, and the opening area of the advance port 61A is “0”. Due to the communication state between the ports, the lubricating oil is supplied to the retarding chamber 39, while the advance chamber 38 is sealed.

FIG. 5B shows the spool 62 in the fifth position with respect to the sleeve 61.
The fifth position indicates a range between the fourth intermediate position and the rightmost position. The fifth position corresponds to the retard mode MB.

  At this time, the opening area on the supply side of the retard port 61B is larger than “0”, and the opening area on the discharge side of the advance port 61A is larger than “0”. Due to the communication state between the ports, the lubricating oil is supplied to the retarding chamber 39 and the lubricating oil in the advance chamber 38 is discharged.

Next, the relationship between the first quasi-holding mode MC1 and the structure of the first OCV 53 will be described.
As described above, the first OCV 53 is dimensionally longer in distance DRs than distance DRp. With this configuration, when the right end of the retard valve 62B matches the right end of the retard port 61B, the right end of the advance valve 62A does not match the right port 61A, and the advance port 61A opens to the supply side. . That is, the first quasi-holding mode MC1 is configured.

A relationship between the second quasi-holding mode MC2 and the structure of the first OCV 53 will be described.
As described above, the first OCV 53 is dimensionally larger in distance DLs than distance DLp. With this configuration, when the left end of the advance valve 62A coincides with the left end of the advance port 61A, the left end of the retard valve 62B does not coincide with the left port 61B, and the retard port 61B opens to the supply side. . That is, the second quasi-holding mode MC2 is configured.

With reference to FIG. 6, the relationship among the duty, the opening area of the advance port 61A and the retard port 61B, and the displacement speed of the exhaust valve timing VTA will be described.
The relationship between the duty and the displacement speed of the exhaust valve timing VTA is as follows: the temperature of the lubricating oil, the hydraulic pressure, the amount of lubricating oil supplied from the oil pump 52, and the magnitude of friction of each sliding component in the variable valve timing mechanism 30A. It changes depending on the situation.

The setting range of values that the duty can take is related to the structure of the first OCV 53, and includes five advance zones ARa, advance quasi-dead zone ARH, intermediate dead zone ARM, retard quasi-dead zone ARL, and retard zone ARb. Divided into areas.
The advance angle band ARa corresponds to the advance angle mode MA, that is, the first position.
The advance quasi-dead zone ARH corresponds to the first quasi-holding mode MC1, that is, the second position.
The intermediate dead zone ARM corresponds to the holding mode MC, that is, the third position.
The retarded quasi dead zone ARL corresponds to the second quasi-holding mode MC2, that is, the fourth position.
The retard zone ARb corresponds to the retard mode MB, that is, the fifth position.

  (A) As shown in FIG. 6B, when the duty takes the value of the advance angle band ARa, the first OCV 53 operates in the advance angle mode MA. The opening area on the supply side of the advance port 61A is always larger than the opening area on the discharge side of the retardation port 61B. As the duty decreases, the opening area on the supply side of the advance port 61A and the opening area on the discharge side of the retard port 61B increase. As shown in FIG. 6A, the displacement speed of the exhaust valve timing VTA to the advance side increases as the duty decreases.

  (B) As shown in FIG. 6B, when the duty takes the value of the advance quasi-dead zone ARH, the first OCV 53 operates in the first quasi-holding mode MC1. The advance port 61A opens to the supply side, and the opening area of the retard port 61B is “0”. As the duty increases, the opening area on the supply side of the advance port 61A decreases. As shown in FIG. 6A, the displacement speed of the exhaust valve timing VTA is almost “0” even if the duty is changed.

  (C) As shown in FIG. 6B, when the duty takes the value of the intermediate dead zone ARM, the first OCV 53 operates in the holding mode MC. Since the advance port 61A is closed by the advance valve 62A and the retard port 61B is closed by the retard valve 62B, the opening area on the supply side and the discharge side of the advance port 61A and the retard port 61B The opening areas on the supply side and the discharge side are both “0”. As shown in FIG. 6A, the displacement speed of the exhaust valve timing VTA is almost “0” even if the duty is changed.

  (D) As shown in FIG. 6B, when the duty assumes the value of the retarded quasi-dead zone ARL, the first OCV 53 operates in the second quasi-holding mode MC2. The retardation port 61B opens to the supply side, and the opening area of the advance port 61A is “0”. As the duty decreases, the opening area on the supply side of the retard port 61B decreases. As shown in FIG. 6A, the displacement speed of the exhaust valve timing VTA is almost “0” even if the duty is changed.

  (E) As shown in FIG. 6B, when the duty takes the value of the retard zone ARb, the first OCV 53 operates in the retard mode MB. The opening area on the supply side of the retard port 61B is always larger than the opening area on the discharge side of the advance port 61A. As the duty increases, the opening area on the supply side of the retard port 61B and the opening area on the discharge side of the advance port 61A increase. As shown in FIG. 6A, the displacement speed of the exhaust valve timing VTA to the retard side increases as the duty increases.

  The reason why the displacement speed SP is almost “0” when the duty takes the value of the advance quasi-dead zone ARH is as follows. That is, when the duty is the advance quasi-dead zone ARH, the first OCV 53 is driven in the first quasi-holding mode MC1. In the first quasi-holding mode MC1, the lubricant is supplied to the advance chamber 38, while the retard chamber 39 is sealed and the lubricant in the advance chamber 38 is held, so that the rotation of the vane rotor 35 is suppressed. . The reason why the displacement speed SP is almost “0” when the duty takes the value of the retarded quasi-dead zone ARL is also the same.

Next, valve timing control will be described.
In the valve timing control, the exhaust valve timing VTA is changed to a target valve timing (hereinafter, “target phase angle VTT”). Since the same control is performed for the intake valve timing VTB, only the control of the exhaust valve timing VTA will be described.

  The valve timing control includes feedback control for converging the actual phase angle VTR during the control to the target phase angle VTT, learning control for learning the holding duty (hereinafter referred to as “holding duty learning control”), and exhaust valve timing VTA. And a suppression process for suppressing fluctuations (hereinafter referred to as “variation suppression control”).

The holding duty indicates a duty for maintaining the exhaust valve timing VTA at a predetermined value.
The variation in the exhaust valve timing VTA is a variation in the rotational phase of the vane rotor 35 caused by the loss of the lubricating oil in the advance chamber 38 or the retard chamber 39, that is, the exhaust valve timing VTA varies in the advance side and the retard side. Indicates to do.

Feedback control will be described.
The control device 70 calculates a target phase angle VTT suitable for the same state based on the operating state and engine load state of the internal combustion engine 1. On the other hand, the actual phase angle VTR at the time of the processing is calculated based on the crank angle signal CA and the exhaust cam angle signal DA. These values are updated every calculation cycle. Next, a phase difference VTD between the target phase angle VTT and the actual phase angle VTR is obtained, and a duty corresponding to the phase difference VTD is calculated.

Specifically, the duty is calculated by the following equation (1) using a P gain parameter and a D gain parameter.

Duty = holding duty + P × phase difference + D × phase difference change amount (1)

Phase difference VTD = target phase angle VTT−actual phase angle VTR
“P” indicates a P gain parameter, which is given based on a map showing the relationship between the water temperature, the rotational speed of the internal combustion engine 1 and “P”.
“D” indicates a D gain parameter, which is given based on a map showing the relationship between the water temperature, the rotational speed of the internal combustion engine 1 and “D”.

  According to the feedback control, when the phase difference between the actual phase angle VTR and the target phase angle VTT is large, the duty is set to a value away from the holding duty. At this time, the displacement speed of the exhaust valve timing VTA is large. On the other hand, when the phase difference between the actual phase angle VTR and the target phase angle VTT is small, the duty is set to a value close to the holding duty. At this time, the displacement speed of the exhaust valve timing VTA is small. That is, as the actual phase angle VTR approaches the target phase angle VTT, the displacement speed of the exhaust valve timing VTA is reduced, and the actual phase angle VTR is converged to the target phase angle VTT.

The procedure of the valve timing control process will be described with reference to FIG.
This process is repeatedly executed by the electronic control unit 71 every predetermined calculation cycle.
In step S110, it is determined whether or not the absolute value of the phase difference VTD between the target phase angle VTT and the actual phase angle VTR is greater than the allowable value HA. That is, it is determined whether or not the actual phase angle VTR has converged to the target phase angle VTT.

  When the absolute value of the phase difference VTD is less than or equal to the allowable value HA, the holding duty is stored in step S120, and further the fluctuation suppression process is executed in step S130. In step S140, the first OCV 53 is driven based on the duty.

  On the other hand, when the absolute value of the phase difference VTD is larger than the allowable value HA, the duty is calculated by the feedback control described above in step S150. In step S140, OCV control is performed based on the duty.

Next, holding duty learning control will be described.
The holding duty varies depending on the engine state, for example, the oil temperature of the lubricating oil, the rotational speed of the internal combustion engine 1, and the like. This is because the magnitude of the force required to maintain the vane rotor 35 in a predetermined rotational phase with respect to the housing rotor 31 changes with changes in the viscosity of the lubricating oil, friction between the members of the variable valve timing mechanism 30A, and the like depending on the engine state. Because. For this reason, the holding duty is learned periodically during engine operation.

In the holding duty learning control, the holding duty is learned as follows.
In valve timing control, when the absolute value of the phase difference VTD, which is the difference between the target phase angle VTT and the actual phase angle VTR, is less than or equal to the allowable value HA (negative determination in step S110), the duty related to the determination is held. Remember as. That is, the duty when the exhaust valve timing VTA is maintained at a specific phase angle is stored as the holding duty.

Next, the fluctuation suppression control process will be described.
The fluctuation suppression control process is executed to suppress fluctuations in the exhaust valve timing VTA. First, the cause of the fluctuation of the exhaust valve timing VTA will be described.

  Conventionally, in the valve timing control process, when it is determined that the phase difference VTD between the target phase angle VTT and the actual phase angle VTR is within the allowable value HA and the actual phase angle VTR has converged to the target phase angle VTT, the duty is set. The first OCV 53 is driven based on the holding duty while being stored as the holding duty. Thereby, the exhaust valve timing VTA is maintained at the target phase angle VTT.

  However, the holding duty varies depending on the relationship of parameters such as the frictional force between the exhaust camshaft 24 and the exhaust valve 23 (hereinafter referred to as “cam friction”) and the magnitude of the force in the advance direction of the assist spring 35A. . The cam friction acts in a direction to retard the exhaust valve timing VTA. The force of the assist spring 35A acts in a direction to advance the exhaust valve timing VTA. That is, the direction of the cam friction force and the direction of the assist spring 35A act in opposite directions. Further, the cam friction varies depending on parameters such as the viscosity of the lubricating oil, the temperature, and the rotational speed of the internal combustion engine 1. For this reason, when these parameters become predetermined values, the cam friction force and the force of the assist spring 35A may be balanced. In such a case, a state occurs in which the vane rotor 35 is maintained in a predetermined rotation phase with respect to the housing rotor 31 without applying a rotational force to the vane rotor 35 in a predetermined direction. That is, when such a condition is satisfied, the holding duty becomes a value in the intermediate dead zone ARM as a result of the holding duty learning.

However, when the period during which the exhaust valve timing VTA is maintained with such a holding duty becomes longer, the exhaust valve timing VTA varies.
That is, no lubricating oil is supplied to the advance chamber 38 and the retard chamber 39 when the holding duty takes a value within the intermediate dead zone ARM. On the other hand, since there is a gap in the advance chamber 38 and the retard chamber 39, the lubricating oil gradually escapes from the advance chamber 38 and the retard chamber 39, and air enters the advance chamber 38 and the retard chamber 39. To be included. Then, since the lubricating oil holding the vane rotor 35 with respect to the housing rotor 31 becomes insufficient, the vane rotor 35 rotates in the advance direction or the retard direction with respect to the housing rotor 31. That is, the exhaust valve timing VTA is not maintained at a predetermined phase angle and varies.

  Since fluctuations in the exhaust valve timing VTA reduce the accuracy of combustion control, it is preferable to avoid this. Therefore, fluctuation suppression process control is executed to suppress fluctuations in the exhaust valve timing VTA.

With reference to FIG. 8, the fluctuation suppressing process will be described.
In step S210, when the holding duty is stored in the valve timing control (step S120), it is determined whether or not the holding duty is within the intermediate dead zone ARM. Then, when it is determined that the holding duty is not within the intermediate dead zone ARM, the processing is terminated. That is, the first OCV 53 is driven using the holding duty at the time of arithmetic processing, and the exhaust valve timing VTA is maintained.

On the other hand, when it is determined that the holding duty is within the intermediate dead zone ARM, the process proceeds to the next step.
In step S220, instead of the holding duty, the duty is set to a specific value in the advance angle quasi-dead zone ARH. The specific value is, for example, an intermediate value in the advance quasi-dead zone ARH. Thereby, since the lubricating oil is supplied into the advance chamber 38, the amount of the lubricant in the advance chamber 38 is suppressed from being reduced. Further, since the retard port 61B is closed, the rotation of the vane rotor 35 accompanying the supply of the lubricating oil in the advance chamber 38 is suppressed. That is, fluctuations in the exhaust valve timing VTA can be suppressed while the exhaust valve timing VTA is maintained.

  Since the value of the holding duty is not changed, the duty for driving the first OCV 53 is calculated using the holding duty stored by the holding duty learning when calculating the duty in the feedback control.

With reference to FIG. 9, an example of transition of the actual phase angle VTR and the duty when the target phase angle VTT is changed in the valve timing control will be described.
A time t0, that is, a state where the exhaust valve timing VTA converges to the target phase angle VTT is shown. At this time, the duty input to the first OCV 53 is a holding duty. The holding duty is in the advance quasi-dead zone ARH.

  The target phase angle VTT is changed according to the time t1, that is, the engine operating state. For example, the target phase angle VTT is set to a value closer to the advance side than the actual phase angle VTR at the same time. At this time, the duty is set to a value smaller than the duty at the time of processing, that is, a predetermined value in the advance zone ARa. Then, by the feedback control, the duty is set to a value close to the holding duty as the actual phase angle VTR approaches the target phase angle VTT.

  At time t2, that is, the absolute value of the phase difference VTD that is the difference between the target phase angle VTT and the actual phase angle VTR is equal to or less than the allowable value HA. At this time, it is determined that the actual phase angle VTR has converged to the target phase angle VTT, and the duty at the time of the determination is stored as a holding duty (step S120).

  Then, it is determined whether or not the holding duty is within the intermediate dead zone ARM. In this example, the holding duty is in the intermediate dead zone ARM. Therefore, instead of the holding duty, an intermediate value of the advance quasi-dead zone ARH is used as a duty for controlling the first OCV 53. That is, the first OCV 53 is driven based on the intermediate value as the duty.

Hereinafter, the control of this embodiment will be described in comparison with the conventional control.
Conventionally, when the absolute value of the phase difference VTD, which is the difference between the target phase angle VTT and the actual phase angle VTR, becomes equal to or less than the allowable value HA at time t2, the duty at the time of the determination is stored as a holding duty. Then, the first OCV 53 is driven using the holding duty. Then, since the holding duty is within the intermediate dead zone ARM, no lubricating oil is supplied to the advance chamber 38 and the retard chamber 39, so that the lubricant is gradually discharged from the advance chamber 38 and the retard chamber 39, and the vane rotor 35. Rotates in the advance direction and the retard direction with respect to the housing rotor 31. That is, the exhaust valve timing VTA varies as shown by the broken line in FIG.

  On the other hand, in the present embodiment, as shown above, an intermediate value of the advance quasi-dead zone ARH is used as the holding duty instead of the holding duty. For this reason, since the lubricating oil is supplied to the advance chamber 38, it is possible to suppress a small amount of the lubricating oil in the advance chamber 38. Further, since the retard chamber 39 is sealed, the vane rotor 35 is prevented from rotating forward with respect to the housing rotor 31 based on the supply of the lubricating oil to the advance chamber 38.

According to this embodiment, the following effects can be obtained.
(1) In this embodiment, when the holding time is equal to or longer than the predetermined time, the lubricating oil supply mode of the first OCV 53 (oil path changing mechanism) is changed to a mode other than the holding mode MC.

  The holding time indicates a period for holding the supply mode of the first OCV 53 in the holding mode MC. That is, in the present embodiment, the period from the time when the duty takes a value within the intermediate dead zone ARM to the time when the new holding duty is stored corresponds to the holding time.

  In the holding mode MC, the lubricating oil is not supplied to the variable valve timing mechanism 30A (variable valve mechanism). On the other hand, in the variable valve timing mechanism 30A, the internal lubricating oil leaks from the clearance of the parts. For this reason, if the holding mode MC is maintained for a predetermined time or more, the exhaust valve timing VTA becomes unstable. However, conventionally, since the first OCV 53 is driven in the holding mode MC unless there is an instruction to change the exhaust valve timing VTA, the period (holding time) in the holding mode MC may be maintained for a predetermined time or more.

  In this regard, in the above configuration, the holding time is suppressed from being a predetermined time or longer. For this reason, the state where the exhaust valve timing VTA becomes unstable is suppressed from continuing for a long period of time. Further, since this effect is obtained by the control of the first OCV 53, the structure of the variable valve timing mechanism 30A is simpler than that of the conventional variable valve timing mechanism 30A.

  (2) In the present embodiment, when the exhaust valve timing VTA is maintained in the valve timing control, the first OCV 53 is driven in the first semi-holding mode MC1 instead of the control in the holding mode MC.

  In the first quasi-holding mode MC1, since the lubricating oil is supplied to the advance chamber 38, the amount of the lubricant that has escaped from the advance chamber 38 can be supplemented. Thereby, the fluctuation | variation of the rotation phase of the vane rotor 35 which arises because the lubricating oil of the advance angle chamber 38 decreases can be suppressed. Further, since the lubricating oil in the retard chamber 39 is retained, it is possible to suppress the rotational phase of the vane rotor 35 with respect to the housing rotor 31 from deviating from the predetermined rotational phase. That is, according to the above configuration, the exhaust valve timing VTA can be suppressed from fluctuating while the exhaust valve timing VTA is maintained at a predetermined phase angle.

  (3) In the present embodiment, when the holding duty is set to a value corresponding to the holding mode MC, when there is a command to maintain the exhaust valve timing VTA, the duty corresponds to the first quasi-holding mode MC1. Set to value.

  In the conventional variable valve operating apparatus 20, when there is a command to maintain the exhaust valve timing VTA at a predetermined phase angle, the duty of the first OCV 53 is set to the holding duty to control the supply mode of the lubricating oil. However, when the holding duty is set to a value corresponding to the holding mode MC, the lubricating oil in the valve timing variable mechanism 30A gradually decreases because the lubricating oil is not supplied to the advance chamber 38 and the retard chamber 39. . For this reason, the rotational phase of the vane rotor 35 with respect to the housing rotor 31 changes, and the exhaust valve timing VTA changes to the advance side and the retard side.

  In this regard, in the above configuration, when there is a command to maintain the exhaust valve timing VTA at a predetermined phase angle, the following processing is performed when the holding duty is set to a value corresponding to the holding mode MC. That is, instead of setting the duty for driving the first OCV 53 to the holding duty, the duty of the first OCV 53 is set to a value corresponding to the first quasi-holding mode MC1, that is, a value in the advance quasi-dead zone ARH.

  As a result, since the lubricant oil can be continuously supplied into the variable valve timing mechanism 30A, the lubricant oil in the variable valve timing mechanism 30A is suppressed from gradually decreasing. And the fluctuation | variation of the rotation phase of the vane rotor 35 with respect to the housing rotor 31, ie, the fluctuation | variation of the exhaust valve timing VTA to the advance side and the retard side, is suppressed.

(4) In the present embodiment, the configurations (1) to (3) are applied to the variable valve timing mechanism 30A provided with the assist spring 35A (full range assist mechanism).
In the intake side variable valve timing mechanism 30 </ b> B, a force (hereinafter, “retarding force”) is applied in a direction opposite to the rotation direction of the vane rotor 35 due to cam friction of the intake valve 21. The vane rotor 35 tends to rotate toward the retard side. For this reason, when maintaining the intake valve timing VTB, it is necessary to apply a force to the advance side so as to cancel the retarding force. Therefore, even when the intake valve timing VTB is maintained, the duty is applied to the advance chamber 38. It is often set to a value corresponding to the supply mode for supplying the lubricating oil. For this reason, the occurrence frequency that the lubricating oil in the variable valve timing mechanism 30B decreases, that is, the fluctuation of the vane rotor 35 with respect to the housing rotor 31 increases is not high.

  On the other hand, the variable valve timing mechanism 30A on the exhaust side rotates the vane rotor 35 to the advance side in response to a request to arrange the vane rotor 35 in the most advanced rotation phase with respect to the housing rotor 31 when the internal combustion engine 1 is stopped. Thus, an assist spring 35A for applying force is provided. In this type of variable valve timing mechanism 30A, the rotational force to the retard side of the vane rotor 35 caused by cam friction of the exhaust valve 23 may be balanced with the force of the assist spring 35A. In this case, when maintaining the exhaust valve timing VTA, it is not necessary to apply a force to the advance side so as to cancel the retard force as described above, so the duty is a value corresponding to the holding mode MC (in the intermediate dead zone ARM). Value). For this reason, the lubricating oil in the variable valve timing mechanism 30A is reduced, and the rotational phase of the vane rotor 35 with respect to the housing rotor 31 varies.

  In this regard, in the above configuration, the control period of the holding mode MC in the control of the exhaust valve timing VTA is limited to the variable valve timing mechanism 30A having the assist spring 35A. Specifically, when the holding duty is set in the intermediate dead zone ARM, the duty is set to a value in the advance angle quasi dead zone ARH. For this reason, it is possible to suppress an increase in fluctuation of the vane rotor 35 relative to the housing rotor 31 due to a decrease in the lubricating oil in the variable valve timing mechanism 30A.

(Other embodiments)
In addition, the embodiment of the present invention is not limited to the embodiment exemplified in the above-described embodiment, and can be implemented by changing it as shown below, for example. The following modifications are not applied only to the above-described embodiment, and different modifications can be combined with each other.

  In the above embodiment, in step S220, instead of the holding duty, the duty is set to a specific value within the advance quasi-dead zone ARH, but the value used instead of the holding duty is not limited to this.

  For example, a specific value in the retarded quasi dead zone ARL can be used. That is, the value used in place of the holding duty can be set within the range of the advance quasi dead zone ARH or the retard quasi dead zone ARL.

  Further, as values used in place of the holding duty, the values of the advance angle band ARa and the retard angle band ARb may be used. However, in this case, it is considered that the exhaust valve timing VTA changes.

  In the above embodiment, in step S220, instead of the holding duty, the duty is set to a specific value within the advance quasi-dead zone ARH. The learned holding duty is maintained without being changed for feedback control.

  On the other hand, instead of such control, the learned holding duty itself may be changed and the first OCV 53 may be driven using the changed holding duty. In this case, since the process of changing the holding duty itself is performed, a duty different from the learned holding duty is used in the feedback control. However, in the feedback control, feedback based on the phase difference VTD is added in the calculation performed periodically, and it is considered that the valve timing control is hardly caused by this. For this reason, the change of the holding duty is allowed. And the effect according to said (1)-(4) is show | played also by such fluctuation | variation suppression control.

The following modification is mentioned as a control aspect which suppresses the fluctuation | variation of the exhaust valve timing VTA.
(A) It is determined that the holding duty is within the intermediate dead zone ARM, and then the first OCV 53 is controlled using the holding duty over a certain period. Then, after a certain period, the first OCV 53 is controlled by setting the duty to a value within the advance quasi-dead zone ARH or the retard quasi-dead zone ARL instead of the holding duty. That is, when it is determined that the holding duty is within the intermediate dead zone ARM, the time (holding time) in which the holding duty is used is limited.

  (B) When the duty is set to a value in the intermediate dead zone ARM by feedback control, the duty is set to a value in the advanced quasi dead zone ARH or the retarded quasi dead zone ARL. That is, the first OCV 53 is not controlled using the value in the intermediate dead zone ARM even during a period other than when the exhaust valve timing VTA is maintained at a predetermined angle.

  (C) As a duty for controlling the first OCV 53, a condition for using the value of the advance quasi-dead zone ARH or the retard quasi-dead zone ARL instead of the holding duty is set. For example, the control using the value of the advance quasi-dead zone ARH or the retard quasi-dead zone ARL instead of the holding duty is limited by the water temperature or the rotational speed of the internal combustion engine 1 or the like.

  That is, factors that cause fluctuations in the exhaust valve timing VTA are related to the oil temperature, oil pressure, viscosity, and the like of the lubricating oil. For this reason, conditions under which fluctuations in the exhaust valve timing VTA are likely to occur are determined in relation to the water temperature related to these parameters and the rotational speed of the internal combustion engine 1. When this condition is satisfied, that is, when the exhaust valve timing VTA is likely to fluctuate, the holding duty is changed.

  The frequency of controlling the valve timing variable mechanism 30A with the duty in the intermediate dead zone ARM also decreases by the above controls (a) to (c), so that the above control conforms to the above (1) to (4). There is an effect.

  In the above embodiment, the present invention is applied to the variable valve timing mechanism 30A having the assist spring 35A that applies the force for rotating the vane rotor 35 to the advance side from the most retarded rotation phase to the most advanced rotation phase. However, the application of the present invention is not limited only to the variable valve timing mechanism having this type of assist spring 35A. For example, the present invention can be applied not only to the exhaust side variable valve timing mechanism 30A but also to the intake side variable valve timing mechanism 30B.

  The present invention can also be applied to a variable valve timing mechanism 30A having an assist spring 35A (partial assist mechanism) that applies a force for rotating the vane rotor 35 to the advance side only in a part of the rotation range of the vane rotor 35. For example, the present invention can be applied to the intake side valve timing varying mechanism 30B having the assist spring 35A that applies force to the advance side over the range from the intermediate angle rotation phase to the most retarded angle rotation phase. The intermediate angle indicates a valve timing between the most advanced angle VTmax and the most retarded angle VTmin, and the intermediate angle rotation phase indicates a rotation phase corresponding to the intermediate angle.

  The present invention can also be applied to a variable valve timing mechanism that does not include the assist spring 35A. In any configuration, the effects according to the above (1) to (4) are achieved.

  In the above embodiment, the present invention is applied to the variable valve operating apparatus 20 having the holding duty learning control. However, the present invention is also applied to the variable valve operating apparatus 20 that does not execute the holding duty learning control. can do.

  In the above embodiment, the present invention is applied to the variable valve timing mechanism 30A having the phase locking mechanism 40 that maintains the exhaust valve timing VTA at a specific phase angle. However, the variable valve timing mechanism 30A without the phase locking mechanism 40 is used. The present invention can also be applied to.

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 10 ... Engine main body, 11 ... Cylinder block, 12 ... Cylinder head, 13 ... Oil pan, 14 ... Combustion chamber, 15 ... Crankshaft, 20 ... Variable valve apparatus, 21 ... Intake valve, 22 ... Intake Camshaft, 23 ... Exhaust valve, 24 ... Exhaust camshaft, 30A ... Exhaust side valve timing variable mechanism (variable valve mechanism), 30B ... Intake side valve timing variable mechanism (variable valve mechanism), 31 ... Housing rotor (Input rotating body), 31A ... partition wall, 32 ... housing main body, 33 ... sprocket, 34 ... cover, 35 ... vane rotor (output rotating body), 35A ... assist spring, 36 ... vane, 37 ... vane housing chamber, 38 ... Advance chamber, 39 ... retard chamber, 40 ... phase locking mechanism, 50 ... lubricating device, 51 ... lubricating oil passage, 52 ... oil pump, 53 ... first OCV (oil passage changing mechanism), 54 ... second OCV (oil passage changing mechanism), 55 ... third OCV, 61 ... sleeve, 61A ... advance port, 61B ... retard port, 61C ... supply port, 61D ... advance discharge Port, 61E ... Delay angle discharge port, 62 ... Spool, 62A ... Advance valve, 62B ... Delay valve, 70 ... Control device, 71 ... Electronic control device, 72 ... Crank position sensor, 73A ... Exhaust cam position sensor, 73B ... Intake cam position sensor.

Claims (1)

A variable valve mechanism that changes the valve timing by changing the rotation phase of the output rotor relative to the input rotor according to the supply mode of the lubricating oil to the advance chamber and the retard chamber, and to the advance chamber and the retard chamber In a variable valve operating apparatus for an internal combustion engine, comprising: an oil passage changing mechanism that controls a supply mode of lubricating oil; and a control device that controls the valve timing by controlling the supply mode of the lubricating oil of the oil passage changing mechanism. ,
As a supply mode of the lubricating oil of the oil passage changing mechanism, at least a holding mode for holding the lubricating oil in the advance chamber and holding the lubricating oil in the retard chamber is provided.
The holding time is the time for holding the supply mode of the lubricating oil of the oil path changing mechanism in the holding mode.
When the holding time is equal to or longer than a predetermined time, the lubricating oil supply mode of the oil passage changing mechanism is changed to a mode other than the holding mode.

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