JP2013036374A - Valve timing control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a valve timing control device for an internal combustion engine which quickly performs lock release of a lock mechanism when valve timing is changed after an engine start, and meantime can increase frequency that the valve timing is locked to most advanced angle timing or most retarded angle timing through the lock mechanism when the engine is stopped.SOLUTION: In the lock mechanism, the lock state is released as hydraulic oil is supplied to a retarded angle chamber 52 through a control valve 23 at hydraulic pressure of lock release pressure or more, and the lock release pressure is set lower than phase changing pressure. Further, in a supply passage 21A, a check valve 24 is provided which restricts discharge of hydraulic oil from the advanced angle chamber 51 when hydraulic oil is supplied to the advanced angle chamber 51 via a supply path 21A through switching operation by the control valve 23 to change a relative rotational phase.

Description

  The present invention changes the relative rotational phase of the first rotating body interlocking with the crankshaft and the second rotating body interlocking with the camshaft through the operation of supplying and discharging hydraulic oil to and from each of the advance angle and retard angle hydraulic chambers. The variable mechanism that makes the valve timing variable, the control valve that performs the switching operation to switch the supply / discharge state of hydraulic oil to each hydraulic chamber, and the relative rotation phase locked to the most advanced angle phase or the most retarded angle phase The present invention relates to a valve timing control device for an internal combustion engine having a locking mechanism.

  In a valve timing control device for an internal combustion engine, valve timings of intake valves and exhaust valves that are driven to open and close by a camshaft are changed in accordance with engine operating conditions. Among such valve timing control devices, particularly those having a hydraulic rotation drive type variable mechanism, the valve timing is changed by changing the rotation phase of the camshaft with respect to the crankshaft using the hydraulic oil pressure. The In other words, the variable mechanism includes an advance hydraulic chamber (“advance angle”) defined by a first rotating body that rotates in conjunction with the crankshaft and a second rotating body that rotates in conjunction with the camshaft. Chamber ”) and the hydraulic chamber for retarding (“ retarding chamber ”), changing the supply / discharge state of the hydraulic fluid, and rotating both rotors relative to each other to maintain the target phase. This is controlled so that the valve timing becomes a time according to the engine operating state. In addition, the supply and discharge mode of the hydraulic oil to and from the advance chamber and the retard chamber are controlled by a control valve.

  By the way, under a situation in which almost no hydraulic oil remains in the hydraulic system including the advance chamber and retard chamber of the variable mechanism, such as when a long time has passed since the operation of the internal combustion engine was stopped. When starting the engine, it becomes difficult to maintain the relative rotational phase of the two rotating bodies at a suitable target phase at the time of starting the engine, that is, to maintain the valve timing at a suitable time at the time of starting the engine.

  Therefore, the conventional valve timing control device is equipped with a lock mechanism that mechanically locks the relative rotation phases of the first rotating body and the second rotating body, and the valve timing is controlled when the engine is started through the locking operation of the locking mechanism. I try to lock at the right time. As such a lock mechanism, for example, as described in Patent Document 1, a mechanism is proposed in which the relative rotational phase of both rotating bodies is locked to the most retarded angle phase, that is, the valve timing of the intake valve is locked to the most retarded angle timing. ing. In both of these rotary bodies, a lock pin provided on one rotary body is urged toward the other rotary body by a spring, and this lock pin fits into a lock hole provided on the other rotary body. The locked state is maintained. On the other hand, by supplying hydraulic oil to the advance chamber, the hydraulic pressure at which the lock pin is pulled out of the lock hole against the elastic force of the spring, that is, the minimum pressure of hydraulic oil that can release the locked state The lock state is released by applying an oil pressure equal to or higher than (unlock pressure Pα) to the lock pin. That is, the hydraulic oil supplied to the advance chamber has a role of releasing the locked state in addition to the role of changing the relative rotation phase to the target phase.

  Although not described in Patent Document 1, when locking the valve timing of the exhaust valve, it is usually preferable to lock the relative rotational phase of both rotating bodies to the most advanced angle phase.

JP 2001-227311 A

  By the way, when the valve timing is changed after the engine is started, it is necessary to change the relative rotational phase of both rotating bodies after unlocking. This is because if the relative rotation phase of both rotating bodies is changed while the unlocking is incomplete, the lock pin is caught in the lock hole and the relative rotating phases of both rotating bodies cannot be changed quickly. In order to solve this, in addition to cam torque fluctuation, the minimum amount of hydraulic oil that can change the relative rotational phase of both rotating bodies against the inertial force of the second rotating body, the frictional force of each part, etc. When the unlocking pressure Pα is set smaller than the pressure (phase change pressure Pβ), the unlocking is completed in advance when the hydraulic oil pressure increases as the engine rotational speed increases, and then both rotors rotate relative to each other. It is desirable to make it.

  However, if the magnitude relationship between the phase change pressure Pβ and the lock release pressure Pα is set in this way, the hydraulic oil supplied to the advance chamber or retard chamber through the oil pump as the engine speed decreases when the engine is stopped. Even if the pressure (supply pressure P) decreases, the lock mechanism does not easily shift to the locked state. This is due to the following reason. In other words, the engine is locked when the engine speed decreases until the supply pressure P becomes less than the unlock pressure Pα. However, when the supply pressure P is lower than the phase change pressure Pβ, the advance angle is increased due to the cam torque fluctuation. The hydraulic oil supplied to the chamber or the retard chamber flows backward through the supply path. For this reason, the relative rotational phase fluctuates between an advance angle and a retard angle, and the lock pin cannot be quickly fitted into the lock hole.

  The present invention has been made in view of such circumstances, and its purpose is to promptly release the lock mechanism when changing the valve timing after the engine is started, while using the lock mechanism when the engine is stopped. An object of the present invention is to provide a valve timing control device for an internal combustion engine that can increase the frequency at which the valve timing is locked at the most advanced timing or the most retarded timing.

  In the valve timing control device according to the present invention, the variable mechanism makes the valve timing of the exhaust valve variable, and the lock mechanism locks the relative rotational phase of both rotating bodies at the most advanced angle phase, that is, the valve timing is adjusted. It is assumed that it will lock at the most advanced time. Further, the lock mechanism releases the lock state when hydraulic oil is supplied to the retard chamber through the control valve with a hydraulic pressure equal to or higher than the lock release pressure Pα, and the lock release pressure Pα is used as the phase change pressure. It is set lower than Pβ. Further, in the supply path for supplying hydraulic oil to the advance hydraulic chamber through the switching operation by the control valve, the hydraulic oil is discharged from the advance hydraulic chamber when the relative rotation phase is changed in the supply path. There is a valve that regulates this.

  Since the unlocking pressure Pα is set to be smaller than the phase change pressure Pβ, when changing the valve timing after the engine is started, the unlocking is first performed and then the relative rotational phase of both rotating bodies is changed. In other words, it is possible to avoid a situation in which the relative rotation phase of both rotating bodies is changed and the lock pin is caught in the lock hole in the state where the unlocking is incomplete.

  On the other hand, even if the supply pressure P of hydraulic oil to the advance chamber drops below the phase change pressure Pβ as the engine rotational speed decreases when the engine is stopped, the hydraulic oil in the advance chamber is affected by cam torque fluctuations. The valve can be prevented from flowing back into the supply path, and the relative rotational phase of both rotating bodies changed to the most advanced angle phase can be prevented from changing to the retarded angle side. As a result, when the hydraulic oil supply pressure P to the advance chamber drops below the unlock pressure Pα, the lock pin is easily inserted into the lock hole, and the valve timing is set to the most advanced angle through the lock mechanism when the engine is stopped. The frequency of being locked can be increased.

  On the other hand, in the case of a valve timing control device that makes the valve timing of the intake valve variable, the locking mechanism locks the relative rotational phase of both rotating bodies at the most retarded phase, that is, locks the valve timing to the most retarded timing. Adopt things. Further, the lock mechanism releases the lock state as hydraulic oil is supplied to the advance chamber through the control valve with a hydraulic pressure equal to or higher than the lock release pressure Pα, and this lock release pressure Pα is used as the phase change pressure. It is set lower than Pβ. Further, in the supply path for supplying hydraulic oil to the retarding hydraulic chamber through the switching operation by the control valve, the hydraulic oil is discharged from the retarding hydraulic chamber when the relative rotation phase is changed in the supply path. There is a valve that regulates this.

  Even in such a configuration, since the unlocking pressure Pα is set smaller than the phase change pressure Pβ, when changing the valve timing after the engine is started, the unlocking is first performed and then the relative rotation of the two rotating bodies is performed. The phase is changed. In other words, it is possible to avoid a situation in which the relative rotation phase of both rotating bodies is changed and the lock pin is caught in the lock hole in the state where the unlocking is incomplete. Furthermore, even if the hydraulic oil supply pressure P to the retarded angle chamber falls below the phase change pressure Pβ as the engine rotational speed decreases when the engine is stopped, the hydraulic fluid flows from the retarded chamber due to the cam torque fluctuation. The reverse flow of the supply path can be suppressed by the valve, and the relative rotation phase of both rotating bodies changed to the most retarded phase can be suppressed from changing to the advance side. As a result, the lock pin is easily inserted into the lock hole when the hydraulic oil supply pressure P to the retard chamber is lower than the unlock pressure Pα, so that the valve timing is set to the most retarded timing through the lock mechanism when the engine is stopped. The frequency of being locked can be increased.

  In addition, in the structure of Claim 1, Claim 2, as a valve provided in a supply path, the non-return valve which always controls that a hydraulic fluid flows back through a supply path is employable, for example. In addition, control is performed so as to restrict the backflow of the hydraulic oil supply path only in the rotational phase range of the camshaft, where the rotating bodies are relatively rotated due to cam torque fluctuations and the hydraulic oil is assumed to flow back through the supply path. Can also be used.

1 is a schematic configuration diagram of a valve timing control device according to an embodiment of the present invention and an internal combustion engine in which the valve timing control device is mounted. (A) is sectional drawing which shows the cross-sectional structure of the variable mechanism about the valve timing control apparatus, (b) is sectional drawing which shows the cross-sectional structure which followed the DA-DA line of (a). Sectional drawing which shows the cross-section of a locking mechanism. The schematic diagram which shows the distribution | circulation aspect of hydraulic fluid. The graph which shows the relationship between supply pressure and engine speed.

  First, the overall configuration of the valve timing control device according to the present invention will be described with reference to FIG. In addition to the intake valve timing control device 1, the internal combustion engine 10 is equipped with an exhaust valve timing control device 2 that embodies the present invention. The exhaust valve timing control device 2 includes a variable mechanism 40 for changing the valve timing, a lock mechanism 80 for mechanically locking the valve timing to the most advanced timing, and the variable mechanism 40 and the lock mechanism 80. A hydraulic oil passage 21 for supplying and discharging hydraulic oil, a control valve 23 provided in the hydraulic oil passage 21 for controlling the supply and discharge state of the hydraulic oil, and a valve switching position of the control valve based on the engine operating state. It is comprised by the control part 90 etc. which control to switch.

  As shown in FIG. 1, the internal combustion engine 10 is provided with an intake camshaft 32 that opens and closes an intake valve 31 and an exhaust camshaft 42 that opens and closes an exhaust valve 41 in a rotatable manner. The intake camshaft 32 is provided with a variable mechanism 30 that changes the valve timing of the intake valve 31. Similarly, the exhaust camshaft 42 is provided with a variable mechanism 40 that changes the valve timing of the exhaust valve 41.

  The intake sprocket 35 and the exhaust sprocket 45 provided in each of the variable mechanisms 30 and 40 and the sprocket 12 of the crankshaft 11 are drivingly connected via a timing chain 13. The intake sprocket 35 is fixed to the cam shaft 32, while the exhaust sprocket 45 is fixed to the cam shaft 42. For this reason, when the crankshaft 11 rotates, the rotational force is transmitted to the sprockets 35 and 45 via the timing chain 13, and the intake and exhaust camshafts 32 and camshafts 42 rotate.

  The intake valve 31 is urged in the valve closing direction by a valve spring 34 for intake. When the intake camshaft 32 rotates, the intake valve 31 is pressed by the cam 33 of the camshaft 32 and opens against the elastic force of the valve spring 34. The exhaust valve 41 is urged in the valve closing direction by an exhaust valve spring 44. When the exhaust cam shaft 42 rotates, the exhaust valve 41 is pressed by the cam 43 of the cam shaft 42 and opens against the elastic force of the valve spring 44.

  The internal combustion engine 10 is provided with an engine-driven oil pump 22 that is driven by the rotational force of the crankshaft 11 and discharges the hydraulic oil of the oil pan 20 to the supply passage 21A. A hydraulic oil passage 21 (supply passage 21A, discharge passage 21B, advance oil passage 60, retard oil passage 70) for supplying and discharging hydraulic equipment such as 40 is provided. The hydraulic oil passage 21 is provided with a control valve 23 that changes the supply / discharge state of the hydraulic oil with respect to the variable mechanism 40. Further, a check valve 24 for restricting the backflow of the working oil is provided in the supply passage 21 </ b> A located on the upstream side of the control valve 23 in the working oil passage 21.

  As described above, since the oil pump 22 is an engine-driven pump driven by the crankshaft 11, the hydraulic oil supply pressure P supplied to each hydraulic chamber of the variable mechanism 40 is equal to the discharge pressure of the oil pump 22. Almost equal. As for the variable mechanism 30 of the intake valve timing control device 1, as with the variable mechanism 40, the supply / discharge state of the hydraulic oil is changed by the control valve, but the description of the control valve and the like is omitted. .

  Further, a crank angle sensor 91 and cam angle sensors 92A and 92B are attached to the internal combustion engine 10 in order to detect the engine operating state. The crank angle sensor 91 is provided in the vicinity of the crankshaft 11 and detects the crank angle and the engine rotational speed NE. The cam angle sensor 92A is provided in the vicinity of the intake camshaft 32 and detects the cam angle (rotation phase) of the camshaft 32. Similarly, the cam angle sensor 92B is provided in the vicinity of the exhaust cam shaft 42 and detects the cam angle (rotation phase) of the cam shaft 42. Signals output from various sensors including the crank angle sensor 91 and the cam angle sensors 92A and 92B are taken into the control unit 90 of the internal combustion engine 10.

  In the valve timing control device 2 for exhaust, the control unit 90 calculates the target valve timing of the exhaust valve 41 based on the engine operating state such as the engine load and the engine speed NE. Further, the actual valve timing of the exhaust valve 41 is detected based on the crank angle detected by the crank angle sensor 91 and the cam angle sensor 92B and the rotational phase of the cam shaft 42, respectively. Then, the control valve 23 is controlled so that the actual valve timing of the exhaust valve 41 coincides with the target valve timing. The valve timing control mode described above is the same for the intake valve timing control device 1.

Next, the configuration of the variable mechanism 40 of the exhaust valve timing control device 2 will be described with reference to FIG.
As shown in FIG. 2A, the vane rotor 46 includes a boss 46B fixed to the end of the cam shaft 42, and three vanes 46A extending from the boss 46B to the radially outer side of the cam shaft 42. It rotates integrally with the cam shaft 42. The housing rotor 47 has a sprocket 45 fixed to one end side of the housing main body 48 and a cover 49 fixed to the other end side. Since the timing chain 13 is engaged with the exhaust sprocket 45, the intake sprocket 35 (see FIG. 1), and the sprocket 12 of the crankshaft 11 (see FIG. 1), the housing rotor 47, The cover 49, the housing main body 48, and the sprocket 45 rotate integrally around the axis C of the cam shaft 42 as with the vane rotor 46.

  The housing body 48 is formed with three partition walls 48A that project in the radial direction toward the axis C of the housing rotor 47, and three housing chambers 50 are formed between adjacent partition walls 48A. Has been. In each of the storage chambers 50, a plurality of hydraulic chambers partitioned by the vanes 46A, that is, an advance chamber 51 and a retard chamber 52 are formed.

  In each storage chamber 50, each advance chamber 51 is located behind the vane 46A in the rotational direction RA of the cam shaft 42. On the other hand, in each accommodating chamber 50, each retarded angle chamber 52 is located in front of the vane 46A in the rotational direction RA of the cam shaft 42.

  The vane rotor 46 has an advance oil passage 60 through which the hydraulic oil supplied to each advance chamber 51 and the hydraulic oil discharged from each advance chamber 51 circulates. It is formed in a mode that extends toward C. Similarly, the vane rotor 46 has a retard oil passage 70 through which the hydraulic oil supplied to each retard chamber 52 and the hydraulic oil discharged from each retard chamber 52 flows from each retard chamber 52 to the camshaft 42. It forms in the aspect extended | stretched toward the axial center C of this.

Next, the operation mode of the variable mechanism 40 will be described.
The hydraulic oil is supplied to each advance chamber 51 through each advance oil passage 60, while the hydraulic oil is discharged from each retard chamber 52 through each retard oil passage 70, whereby the vane rotor 46 is moved to the housing rotor 47. On the other hand, it rotates in the advance side, that is, in the rotation direction RA of the cam shaft 42. As a result, the valve timing is advanced. As described above, the vane rotor 46 rotates in the rotation direction RA and the vane 46A in each storage chamber 50 comes into contact with the partition wall 48A, so that the valve timing becomes the most advanced timing.

  On the other hand, hydraulic oil is supplied to each retarded angle chamber 52 through each retarded angle oil passage 70, while hydraulic oil is discharged from each advanced angle chamber 51 through each advanced angle oil passage 60, so that the vane rotor 46 becomes a housing rotor. Rotate in the retarded direction with respect to 47, that is, in the direction opposite to the rotational direction RA of the cam shaft 42. As a result, the valve timing is retarded. As described above, the vane rotor 46 rotates in the direction opposite to the rotation direction RA, and each vane 46A in each storage chamber 50 comes into contact with the partition wall 48A, so that the valve timing becomes the most retarded timing. As described above, the minimum hydraulic oil pressure that can change the relative rotational phase of the vane rotor 46 and the housing rotor 47 against the inertial force of the vane rotor 46, the frictional force of each part, and the like in addition to the cam torque fluctuations. This is referred to as phase change pressure Pβ. In other words, when the hydraulic oil supply pressure P is equal to or higher than the phase change pressure Pβ, the valve timing is advanced or retarded.

  Further, in the exhaust valve timing control device 2, a lock mechanism 80 for locking the valve timing at the most advanced timing is provided in the vane 46 </ b> A and the housing rotor 47. The structure of the lock mechanism 80 will be described with reference to FIG.

  The lock mechanism 80 includes an accommodation hole 82 provided in the vane 46 </ b> A, a lock pin 81 accommodated in the accommodation hole 82 so as to reciprocate, and a lock hole formed in the housing rotor 47 and engageable with the lock pin 81. 86. The lock hole 86 is formed at a position on the wall surface of the sprocket 45 facing the vane rotor 46 at a position where the lock pin 81 can be fitted when the vane rotor 46 rotates to the most advanced angle phase. Further, in the accommodation hole 82, a spring 83 that urges the lock pin 81 toward the housing rotor 47 is accommodated in a compressed state between the top surface of the lock pin 81 and the wall surface of the cover 49 facing the lock pin 81. Yes.

  Further, the lock mechanism 80 is provided with a retard release chamber 84 to which the hydraulic oil for the retard chamber 52 is supplied in the vane rotor 46, while the advance release chamber 85 to which the hydraulic fluid for the advance chamber 51 is supplied is a housing. The rotor 47 is provided.

  The retard release chamber 84 is defined by the top 81 </ b> B and the side of the lock pin 81 and the inner wall of the accommodation hole 82. On the wall surface of the accommodation hole 82, a retard communication path 84 </ b> A that connects the retard release chamber 84 and the retard chamber 52 is opened. The hydraulic oil supplied to the retard chamber 52 is supplied to the retard release chamber 84 through the retard communication passage 84A. When hydraulic oil is supplied to the retard release chamber 84 in this way, the hydraulic pressure acts on the top 81B of the lock pin 81. When this hydraulic pressure, in other words, the supply pressure P becomes a pressure in the vicinity of the unlocking pressure Pα, the lock pin 81 moves in the direction opposite to the sprocket 45 (accommodating direction ZB ”) against the elastic force of the spring 83. . When the supply pressure P becomes equal to or higher than the unlocking pressure Pα, the lock pin 81 fitted in the lock hole 86 is removed from the lock hole 86, and the lock mechanism 80 is in the unlocked state.

  On the other hand, the advance angle release chamber 85 is configured as a space defined by the inner wall surface of the lock hole 86. On the surface of the vane 46A that faces the sprocket 45, an advance communication path 85A that connects the advance release chamber 85 and the advance chamber 51 is formed. The hydraulic fluid supplied to the advance chamber 51 is supplied to the advance release chamber 85 through the advance communication passage 85A. When hydraulic oil is supplied to the advance angle release chamber 85 in this way, hydraulic pressure acts on the distal end surface 81A of the lock pin 81. When the oil pressure, in other words, the supply pressure P becomes a pressure in the vicinity of the lock release pressure Pα, the lock pin 81 moves in the accommodation direction ZB against the elastic force of the spring 83. When the supply pressure P becomes equal to or higher than the unlocking pressure Pα, the lock pin 81 fitted in the lock hole 86 is removed from the lock hole 86, and the lock mechanism 80 is in the unlocked state.

  On the other hand, when no hydraulic oil is supplied to either the retard release chamber 84 or the advance release chamber 85, the lock pin 81 is biased toward the housing rotor 47 (projecting direction ZA) by the elastic force of the spring 83. . Under such circumstances, when the vane rotor 46 rotates relative to the housing rotor 47 and the lock pin 81 moves to a position corresponding to the lock hole 86, the lock pin 81 protrudes from the vane rotor 46 and fits into the lock hole 86. . As a result, the lock mechanism 80 is locked and the relative rotational phase of the housing rotor 47 and the vane rotor 46 is fixed to the most advanced angle phase.

Next, the relationship between the operation of the variable mechanism 40 and the operation of the lock mechanism 80 will be described.
When there is a request for advancement of the valve timing, hydraulic oil is discharged from the retarded angle chamber 52 through the retarded oil passage 70 and the like by switching operation of the control valve 23, while hydraulic fluid is supplied to the advanced angle chamber 51 and further advances. The hydraulic oil is also supplied from the corner chamber 51 to the advance angle release chamber 85 through the advance communication passage 85A. For this reason, the vane rotor 46 rotates to the advance side with respect to the housing rotor 47 in a state where the lock of the lock mechanism 80 is released.

  On the other hand, when there is a request for retarding the valve timing, hydraulic oil is discharged from the advance chamber 51 through the advance oil passage 60 and the like by switching operation of the control valve 23, while hydraulic oil is supplied to the retard chamber 52. Further, hydraulic oil is also supplied from the retard chamber 52 to the retard release chamber 84 through the retard communication passage 84A. For this reason, the vane rotor 46 rotates to the retard side with respect to the housing rotor 47 in a state where the lock of the lock mechanism 80 is released.

  When the engine is stopped, the most advanced angle request for valve timing is made. When the control valve 23 is switched, hydraulic oil is discharged from the retarded angle chamber 52 through the retarded oil passage 70 and the like. The hydraulic oil is supplied to 51 and further supplied to the advanced angle release chamber 85 from the advanced angle chamber 51 through the advanced angle communication passage 85A. As a result, the vane rotor 46 rotates relative to the housing rotor 47 in the advance side.

  Further, when the engine is stopped, the supply pressure P of the oil pump 22 gradually decreases as the engine rotational speed NE decreases. For this reason, the hydraulic pressure in the advance angle release chamber 85 is lowered, and the lock pin 81 is urged in the protruding direction ZA by the elastic force of the spring 83. When the relative rotational phase of the vane rotor 46 with respect to the housing rotor 47 reaches the most advanced angle phase, the lock pin 81 is fitted into the lock hole 86. As a result, the relative rotational phase of both rotating bodies, that is, the valve timing is fixed at the most advanced timing.

Next, with reference to FIG. 4, the distribution | circulation aspect of hydraulic fluid is demonstrated.
The hydraulic oil discharged from the oil pump 22 is supplied to the control valve 23 through the supply path 21A. The hydraulic fluid circulates as follows according to the supply / discharge state of the control valve 23.

  (A) When the supply / discharge state of the control valve 23 is in the supply / discharge state (first mode) in which the hydraulic oil is supplied to the advance chamber 51 and the hydraulic oil is discharged from the retard chamber 52, the advance oil passage 60 The hydraulic oil is supplied to the advance chamber 51 through the retard chamber 51 and the hydraulic oil in the retard chamber 52 is discharged through the retard oil passage 70. The hydraulic oil discharged from the retard chamber 52 is returned to the oil pan 20 through the control valve 23 and the discharge passage 21B.

  (B) When the supply / discharge state of the control valve 23 is in the supply / discharge state (second mode) where hydraulic oil is supplied to the advance chamber 51 and the flow of hydraulic oil to the retard chamber 52 is blocked, the advance oil The hydraulic oil is supplied to the advance chamber 51 through the passage 60 and the retard oil passage 70 is closed.

  (C) When the supply / discharge state of the control valve 23 is in the supply / discharge state (third mode) that blocks the flow of hydraulic oil to the advance chamber 51 and blocks the flow of hydraulic oil to the retard chamber 52 The corner oil passage 60 and the retard oil passage 70 are closed. That is, the hydraulic pressure in the advance chamber 51 and the retard chamber 52 is kept constant.

  (D) Retarded oil when the supply / discharge state of the control valve 23 is in the supply / discharge state (fourth mode) in which the flow of hydraulic oil to the advance chamber 51 is blocked and the hydraulic oil is supplied to the retard chamber 52 The hydraulic oil is supplied to the retard chamber 52 through the passage 70 and the advance oil passage 60 is closed.

  (E) When the supply / discharge state of the control valve 23 is in the supply / discharge state (fifth mode) in which the hydraulic oil is discharged from the advance chamber 51 and the hydraulic oil is supplied to the retard chamber 52, the advance oil passage 60 The hydraulic oil is discharged from the advance chamber 51 through the delay angle chamber 51 and is supplied to the retard chamber 52 through the retard oil passage 70. The hydraulic oil discharged from the advance chamber 51 is returned to the oil pan 20 through the control valve 23 and the discharge path 21B.

  In the normal engine operating state except when the engine is started or when the engine is stopped, the target valve timing of the exhaust valve 41 is calculated based on the engine operating state such as the engine load and the engine speed NE as described above. Is done. Further, the control unit 90 calculates the actual valve timing of the exhaust valve 41 based on the crank angle and the rotational phase of the camshaft 42, and performs control in the following manner so that the valve timing matches the target valve timing. The valve 23 is controlled.

  When the actual valve timing is retarded from the target valve timing, the first mode is first selected from the above-described modes. That is, the hydraulic oil is supplied to the advance chamber 51 through the advance oil passage 60 and the hydraulic oil in the retard chamber 52 is discharged through the retard oil passage 70. As a result, the valve timing is advanced to make the actual valve timing coincide with the target valve timing. When the actual valve timing matches the target valve timing, the first mode is switched to the second mode described above. That is, hydraulic oil is supplied to the advance chamber 51 through the advance oil passage 60 and the retard oil passage 70 is closed. As a result, the hydraulic pressure in the advance chamber 51 is increased. When the hydraulic pressure in the advance chamber 51 and the retard chamber 52 rises to a predetermined pressure, the second mode is switched to the third mode described above. That is, the advance oil passage 60 and the retard oil passage 70 are closed. In other words, the hydraulic pressure in the advance chamber 51 and the retard chamber 52 is maintained constant, and the actual valve timing is maintained at the target valve timing.

  When the actual valve timing is advanced from the target valve timing, the fifth mode is first selected from the above-described modes. That is, the hydraulic oil is discharged from the advance chamber 51 through the advance oil passage 60 and is supplied to the retard chamber 52 through the retard oil passage 70. Thereby, the valve timing is retarded, and the actual valve timing is made to coincide with the target valve timing. When the actual valve timing matches the target valve timing, the fifth mode is switched to the fourth mode described above. That is, hydraulic oil is supplied to the retard chamber 52 through the retard oil passage 70 and the advance oil passage 60 is closed. As a result, the hydraulic pressure in the retard chamber 52 is increased. When the hydraulic pressure in the retard chamber 52 and the advance chamber 51 rises to a predetermined pressure, the fourth mode is switched to the third mode described above. That is, the advance oil passage 60 and the retard oil passage 70 are closed. In other words, the hydraulic pressure in the advance chamber 51 and the retard chamber 52 is maintained constant, and the actual valve timing is maintained at the target valve timing.

  When the actual valve timing matches the target valve timing, in other words, when it is not necessary to change the actual valve timing, the third mode is selected from the above-described modes. That is, the advance oil passage 60 and the retard oil passage 70 are closed, and the hydraulic pressure in the advance chamber 51 and the retard chamber 52 is maintained constant.

  On the other hand, when the engine is stopped, the valve timing needs to be locked at the most advanced timing, so the first mode is selected from the above-described modes. That is, the hydraulic oil is supplied to the advance chamber 51 through the advance oil passage 60 and the hydraulic oil in the retard chamber 52 is discharged through the retard oil passage 70. However, if the lock mechanism 80 does not shift to the locked state when the hydraulic oil supply pressure P to the advance chamber 51 decreases with a decrease in the engine rotational speed NE, the advance chamber 51 is caused by cam torque fluctuations. May flow back through the advance oil passage 60 and the supply passage 21A. The check valve 24 provided in the supply path 21A has a function of regulating such a back flow.

Next, the relationship between the supply pressure P and the engine speed NE will be described with reference to FIG.
As described above, since the oil pump 22 is driven by the crankshaft 11, as shown in FIG. 5, the hydraulic oil supply pressure P to the advance chamber 51 and the retard chamber 52 is equal to the engine rotational speed NE. Increases with the rise.

  Further, as described above, when the engine is stopped, the valve timing is locked at the most advanced timing. Therefore, when the valve timing is changed after the engine is started, a request for retarding the valve timing is made, and the above-described fifth mode is selected. That is, hydraulic oil is supplied to the retard chamber 52. Here, as shown in FIG. 5, the unlocking pressure Pα is set lower than the phase change pressure Pβ. That is, as the engine rotational speed NE increases to the engine rotational speed NEα, the hydraulic oil supply pressure P to the retard chamber 52 increases and first reaches the unlocking pressure Pα. That is, the lock state of the lock mechanism 80 is released. Thereafter, as the engine rotational speed NE further increases to the engine rotational speed NEβ, the supply pressure P further increases. When the engine rotational speed NE reaches the phase change pressure Pβ, the relative rotational phase of both rotating bodies is changed and the valve timing is delayed. Will be horned. Therefore, it is possible to avoid a situation in which the vane rotor 46 rotates relative to the housing rotor 47 and the lock pin 81 is caught in the lock hole 86 while the unlocking of the lock mechanism 80 is incomplete. As a result, it is possible to quickly rotate the rotors 46 and 47 to change the actual valve timing to the target valve timing.

  On the other hand, when the engine is stopped, the first mode is selected as described above, and the hydraulic oil is supplied to the advance chamber 51 while the hydraulic oil is discharged from the retard chamber 52. As the engine rotational speed NE decreases to the engine rotational speed NEβ, the hydraulic oil supply pressure P to the advance chamber 51 decreases to less than the phase change pressure Pβ. However, at this time, the supply pressure P is greater than the lock release pressure Pα, and therefore the locked state is not achieved. Furthermore, both rotating bodies rotate relative to each other under the influence of cam torque fluctuations, and the hydraulic oil in the advance chamber 51 tends to flow backward. However, as described above, since the check valve 24 is provided in the supply passage 21A, the backflow of the hydraulic oil can be prevented. Then, when the engine speed NE is further reduced to the engine speed NEα, the supply pressure P is reduced to less than the unlocking pressure Pα, so that the locked state is established.

According to this embodiment described above, the following effects can be obtained.
Since the unlocking pressure Pα is set smaller than the phase change pressure Pβ, when changing the valve timing after the engine is started, the relative rotational phase of the vane rotor 46 and the housing rotor 47 is changed after the unlocking is performed first. Is done. In other words, it is possible to avoid a situation in which the relative rotation phase of both rotating bodies is changed and the lock pin 81 is caught in the lock hole 86 in the state where the unlocking is incomplete.

  On the other hand, even if the hydraulic oil supply pressure P with respect to the advance chamber 51 decreases below the phase change pressure Pβ as the engine rotational speed NE decreases when the engine is stopped, the effect of the cam torque variation causes the advance chamber 51 to The check valve 24 can prevent the hydraulic oil from flowing back to the supply path 21A, and can prevent the relative rotational phase of both rotating bodies changed to the most advanced angle phase from changing to the retarded angle side. become able to. As a result, the lock pin 81 is easily inserted into the lock hole 86 when the hydraulic oil supply pressure P to the advance chamber 51 is lower than the lock release pressure Pα, and the valve timing is maximized through the lock mechanism 80 when the engine is stopped. The frequency of locking at the advance angle can be increased.

  Note that the valve timing control device according to the present invention is not limited to the configuration exemplified in the above-described embodiment, and can be implemented in the following form obtained by appropriately modifying this embodiment.

  (A) The configuration of the exhaust valve timing control device 2 exemplified in this embodiment can be applied to the intake valve timing control device 1. That is, in this case, a lock mechanism 80 is used that locks the relative rotational phase of both rotating bodies at the most retarded phase, in other words, locks the valve timing to the most retarded timing. The lock mechanism 80 is unlocked when hydraulic oil is supplied to the advance chamber 51 through the control valve 23 with a hydraulic pressure equal to or higher than the unlock pressure Pα. It is set lower than the phase change pressure Pβ. Further, a check that restricts the discharge of the hydraulic oil from the retard chamber 52 when the hydraulic oil is supplied to the retard chamber 52 through the supply path 21A through the switching operation by the control valve 23 to change the relative rotation phase. A valve 24 is provided in the supply path 21A.

Even with such a configuration, it is possible to achieve an effect according to the above-described effect.
That is, since the unlocking pressure Pα is set to be smaller than the phase change pressure Pβ, when changing the valve timing after starting the engine, the relative rotational phase of both rotating bodies is changed after unlocking is performed first. The In other words, it is possible to avoid a situation in which the relative rotation phase of both rotating bodies is changed and the lock pin 81 is caught in the lock hole 86 in the state where the unlocking is incomplete.

  On the other hand, even if the hydraulic oil supply pressure P to the retard chamber 52 decreases below the phase change pressure Pβ as the engine speed decreases when the engine is stopped, the operation of the retard chamber 52 is affected by the cam torque fluctuation. The check valve 24 can prevent the oil from flowing back to the supply path 21A, and the relative rotation phase of both rotating bodies changed to the most retarded phase can be prevented from changing to the advance side. It becomes like this. As a result, the lock pin 81 is easily inserted into the lock hole 86 when the hydraulic oil supply pressure P to the retard chamber 52 is lower than the lock release pressure Pα, so that the valve timing is controlled through the lock mechanism 80 when the engine is stopped. The frequency of locking at the most retarded angle can be increased.

  (B) Further, the configuration related to the magnitude relationship between the lock release pressure Pα and the phase change pressure Pβ as described above and the configuration related to the valve that restricts the backflow of hydraulic oil from the hydraulic chamber when the engine is stopped are the valve timing control for intake. The present invention may be applied to both the device 1 and the exhaust valve timing control device 2, or may be applied to only one of them.

  (C) The valve provided in the supply passage 21A is not limited to the check valve 24 that constantly restricts the backflow of the hydraulic oil in the supply passage 21A provided in the supply passage 21A as exemplified in the present embodiment, but the cam torque Due to the fluctuation, the vane rotor 46 and the housing rotor 47 rotate relative to each other, and the backflow of the working oil supply passage 21A is restricted only in the relative rotation phase range of both rotating bodies that is assumed to flow back through the supply passage 21A. It is also possible to employ a valve that is controlled in this manner. If such a configuration is adopted, the valve is not limited to the supply passage 21A but may be the advance oil passage 60. Similarly, in the intake valve timing control device 1 described in (a) above, either the configuration in which the valve is disposed in the supply passage 21A or the configuration in which the valve is disposed in the retarded oil passage 70 is used. Can be adopted.

(D) The lock pin 81 can be provided in the housing rotor 47, and the lock hole 86 into which the lock pin 81 is fitted can be provided in the vane rotor 46.
(E) The protruding direction ZA and the accommodating direction ZB related to the lock pin 81 and the lock hole 86 are not limited to the axial direction of the vane rotor 46 illustrated in the present embodiment, and may be the radial direction of the vane rotor 46.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 11 ... Crankshaft, 12 ... Sprocket, 13 ... Timing chain, 20 ... Oil pan, 21 ... Hydraulic oil passage, 21A ... Supply passage, 21B ... Discharge passage, 22 ... Oil pump, 23 ... Control valve, 24 ... Check valve, 30 ... Variable mechanism, 31 ... Intake valve, 32 ... Cam shaft, 33 ... Cam, 34 ... Valve spring, 35 ... Sprocket, 41 ... Exhaust valve, 42 ... Cam shaft, 43 ... Cam, 44 ... Valve spring, 45 ... sprocket, 46 ... vane rotor (second rotating body), 46A ... vane, 46B ... boss, 47 ... housing rotor (first rotating body), 48 ... housing body, 48A ... partition wall, 49 ... Cover, 50 ... Accommodating chamber, 51 ... Advance angle chamber, 52 ... Delay angle chamber, 60 ... Advance angle oil path, 70 ... Delay angle oil path, 80 ... Lock mechanism, 81 ... Lock pin, 81A ... Tip , 81B ... top, 82 ... accommodating hole, 83 ... spring, 84 ... retarding release chamber, 84A ... retarding communication passage, 85 ... advance release chamber, 85A ... advance communication passage, 86 ... lock hole, 90 ... control 91, crank angle sensor, 92A ... cam angle sensor, 92B ... cam angle sensor.

Claims (2)

The relative rotational phase of the first rotating body interlocked with the crankshaft and the second rotating body interlocked with the exhaust camshaft is changed through the operation of supplying and discharging the hydraulic oil to and from each of the advance angle and retard angle hydraulic chambers. Thus, a variable mechanism that makes the valve timing of the exhaust valve variable, a control valve that performs a switching operation for switching the supply / discharge state of hydraulic oil to each hydraulic chamber, and the relative rotation phase are locked to the most advanced angle phase. In a valve timing control device for an internal combustion engine having a lock mechanism,
The lock mechanism is configured to release a lock state when hydraulic oil is supplied to the retardation hydraulic chamber with a hydraulic pressure equal to or higher than the unlock pressure through the control valve, and the unlock pressure is It is set lower than the minimum pressure of hydraulic oil that can change the relative rotation phase,
In the supply path for supplying hydraulic oil to the advance hydraulic chamber through the switching operation by the control valve, the hydraulic oil is supplied from the advance hydraulic chamber to the supply path when the relative rotation phase is changed. A valve timing control device for an internal combustion engine, characterized in that a valve for restricting discharge of the internal combustion engine is provided. The relative rotational phase of the first rotating body interlocked with the crankshaft and the second rotating body interlocked with the intake camshaft is changed through the operation of supplying and discharging hydraulic oil to and from each of the advance and retard hydraulic chambers. Thus, a variable mechanism that makes the valve timing of the intake valve variable, a control valve that performs a switching operation for switching the supply / discharge state of hydraulic oil to each hydraulic chamber, and the relative rotation phase are locked to the most retarded phase. In a valve timing control device for an internal combustion engine having a lock mechanism,
The lock mechanism is configured to release a lock state when hydraulic fluid is supplied to the advance hydraulic chamber with a hydraulic pressure equal to or higher than the lock release pressure through the control valve, and the lock release pressure is It is set lower than the minimum pressure of hydraulic oil that can change the relative rotation phase,
In the supply path for supplying hydraulic oil to the retarding hydraulic chamber through the switching operation by the control valve, the hydraulic fluid is supplied from the retarding hydraulic chamber to the supply path when the relative rotation phase is changed. A valve timing control device for an internal combustion engine, characterized in that a valve for restricting discharge of the internal combustion engine is provided.

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