WO2012086085A1

WO2012086085A1 - Variable valve device for internal combustion engine

Info

Publication number: WO2012086085A1
Application number: PCT/JP2010/073441
Authority: WO
Inventors: 横山　友; 治仁藤村; 慶遠藤
Original assignee: トヨタ自動車株式会社
Priority date: 2010-12-24
Filing date: 2010-12-24
Publication date: 2012-06-28
Also published as: JP5288044B2; JPWO2012086085A1

Abstract

A variable valve device (20) equipped with a hydraulically actuated variable mechanism (25) that changes the valve timing, and a lock mechanism (26) that locks the valve timing during a prescribed period between the most retarded angle period and the most advanced angle period. The lock mechanism (26) has an advanced angle restriction mechanism and a retarded angle restriction mechanism, and the valve timing is mechanically locked for a prescribed period by means of the cooperation of these mechanisms. The advanced angle restriction mechanism and the retarded angle restriction mechanism each have a release chamber to which operating oil is supplied to control the operations of said mechanisms. The supply/discharge of operating oil for these release chambers is controlled by a common OCV (62). A control unit (18) controls the supply/discharge of operating oil for the release chambers of both restriction mechanisms by means of the common OCV (62) so as to always release the pin of the same restriction mechanism, either the advanced angle restriction mechanism or the retarded angle restriction mechanism, before releasing the pin of the other restriction mechanism.

Description

Variable valve operating device for internal combustion engine

The present invention relates to a variable valve operating apparatus for an internal combustion engine, and more particularly to a variable valve operating apparatus including a hydraulically driven variable mechanism that changes valve timing and a lock mechanism that locks the valve timing at a specific time.

As a device mounted on an internal combustion engine, a variable valve operating device having a hydraulically driven variable mechanism that changes valve timing of an intake valve and an exhaust valve driven to open and close by a camshaft according to an engine operating state is known. Yes. The configuration of the variable mechanism of such a variable valve operating apparatus is shown in FIG. FIG. 9A shows the internal structure of the variable mechanism 100 with the cover of the variable mechanism 100 removed, and FIG. 9B shows a cross-sectional structure taken along line BB in FIG. 9A. Indicates. In FIG. 9A, the rotation direction of the camshaft 200 is indicated by an arrow RC.

A variable mechanism 100 shown in FIG. 9 includes two rotating bodies that rotate around the same rotation axis, and one rotating body is sprocket 101 that is drivingly connected to a crankshaft via a chain (not shown). The other rotating body is a vane rotor 103 that is drivingly connected to the camshaft 200. A plurality of vanes 103A provided in the vane rotor 103 are accommodated in a plurality of accommodating chambers 105 formed in the housing 102, and each of the accommodating chambers 105 is advanced and retarded by a vane 103A. It is divided into and. The vane 103A is displaced in the storage chamber 105 by the hydraulic pressure supplied to the advance chamber 106 and the retard chamber 107, and relative rotation occurs between the housing 102 and the vane rotor 103. Relative rotation phase, in other words, the valve timing is changed.

In addition, the variable mechanism 100 is provided with a lock mechanism 110 that locks the valve timing at an intermediate timing between the most retarded angle timing and the most advanced angle timing (hereinafter referred to as “specific timing”). As shown in FIG. 9B, the lock mechanism 110 includes a recess 112 formed in the sprocket 101 and a pin 111 accommodated in the vane 103 A so as to be close to and away from the recess 112. Yes. Further, a spring 113 for biasing the pin 111 is provided in a space for accommodating the pin 111 in the vane 103A, and a release chamber 114 to which hydraulic oil is supplied is formed. The pin 111 is biased by the spring 113 in the direction of fitting into the recess 112, while the pin 111 is released from the recess 112 by a force based on the pressure of the hydraulic oil supplied to the release chamber 114, that is, the pin 111 is released. Biased in the direction.

Then, when a condition for locking the valve timing at a specific time is satisfied, such as when an engine stop is requested, the hydraulic oil is discharged from the release chamber 114. Accordingly, when the hydraulic pressure in the release chamber 114 is lower than the release hydraulic pressure, the pin 111 is fitted into the recess 112 by the urging force of the spring 113. Thus, when the pin 111 fits into the recess 112, the relative rotation between the vane rotor 103 and the housing 102 is mechanically locked. As a result, the valve timing is locked at a specific time.

On the other hand, when a condition for releasing the valve timing from a specific time is satisfied, such as when a change in valve timing is requested, hydraulic fluid is supplied to the release chamber 114. Accordingly, when the hydraulic pressure in the release chamber 114 rises higher than the release hydraulic pressure, the pin 111 is pulled out of the recess 112 by the biasing force based on the hydraulic pressure. By releasing the pin 111 in this manner, the locked state of the relative rotation between the vane rotor 103 and the housing 102 is released. The hydraulic oil is selectively supplied to and discharged from the advance chamber 106 and the retard chamber 107, so that the valve timing locked at the specific time is changed to a time suitable for the engine operating state. In addition, the supply / discharge state of the hydraulic oil with respect to the advance chamber 106 and the retard chamber 107 of the variable mechanism 100 and the release chamber 114 of the lock mechanism 110 is controlled by an oil passage control valve.

In addition, as described in Patent Document 1, for example, two mechanisms for individually limiting the advance angle and the retard angle of the valve timing (hereinafter, referred to as “advance angle limiting mechanism” and “retard angle limiting mechanism”), respectively. There has also been proposed a variable valve apparatus that realizes a lock function in a lock mechanism by operation. In such a lock mechanism, the pin, spring, and release chamber as described above are provided in different vanes of the vane rotor in the advance angle limit mechanism and the retard angle limit mechanism, respectively, while the recess into which each pin can be inserted is a sprocket. Are formed respectively. And, the pin of the advance angle limiting mechanism (hereinafter referred to as “advance limit pin”) is inserted into the corresponding recess, thereby permitting the delay from the specific timing of the valve timing, but only the advance angle. Is regulated. In addition, by inserting a pin of the retard limit mechanism (hereinafter referred to as “retard limit pin”) into the corresponding recess, the advance from the specific timing of the valve timing is allowed, but only the retard is allowed. Is regulated. That is, in such a lock mechanism, the advance angle and retard angle of the valve timing are regulated by inserting the pin of the advance angle limiting mechanism and the pin of the retard angle limiting mechanism into the corresponding recesses respectively, and the valve timing is locked at a specific time. On the other hand, when both the pins are released, the locked state is released.

Japanese Patent Laid-Open No. 2006-9673

By the way, during the engine operation, the valve is driven to open and close by the cam of the camshaft. Therefore, as shown in FIG. 10 (a), let both rotors rotate relative to each other in the direction in which the valve timing changes to the retard side. And a negative torque that relatively rotates both rotating bodies in the direction in which the valve timing changes to the advance side alternately act on the camshaft. That is, as shown in FIGS. 10A and 10B, during the valve opening period, positive torque acts on the camshaft when the valve lift amount increases, while negative torque when the valve lift amount decreases. Torque acts on the camshaft.

Here, in such a lock mechanism including the advance angle limit mechanism and the retard angle limit mechanism, when the lock mechanism is switched from the locked state to the released state, the advance angle limit pin and the delay angle limit pin are rarely released at the same timing. In many cases, one of these pins is released first. Then, under the situation where each hydraulic pressure of the advance angle chamber and the retard angle chamber is not sufficiently increased, one of the advance angle limit pin and the retard angle limit pin is fitted in the recess and the other is released first. If this is done, the valve lift will change as follows according to the pin released earlier.

FIG. 10C shows a change in the valve lift amount when only the retard limit pin is released in a state where the advance limit pin is fitted in the recess. In this case, when the lock mechanism is in the locked state (a broken line) because relative rotation occurs between the two rotating bodies so that the valve timing changes from the specific timing to the retard side due to the positive torque acting on the cam shaft. The valve lift amount is reduced as compared with FIG. On the other hand, even if negative torque acts on the camshaft, the relative rotation between the two rotating bodies in the direction in which the valve timing changes from the specific timing to the advance side is regulated by the advance limit pin. The lift amount does not change.

FIG. 10 (d) shows a change in the valve lift amount when only the advance limit pin is released while the retard limit pin is inserted in the recess. In this case, when the lock mechanism is in a locked state (a broken line) because relative rotation occurs between the two rotating bodies so that the valve timing changes from the specific timing to the advance side due to negative torque acting on the camshaft. The valve lift amount is reduced as compared with FIG. On the other hand, even if positive torque is applied to the camshaft, the relative rotation between the two rotating bodies in the direction in which the valve timing changes from the specific timing to the retard side is restricted by the retard limit pin. The lift amount does not change.

As described above, when the valve lift amount of the intake valve or the exhaust valve changes, the engine operating state such as the engine rotation speed or the intake air amount may change accordingly. Therefore, every time the lock mechanism is switched from the locked state to the released state, if the release order of the advance angle limit pin and the retard angle limit pin is different, the engine operating state also changes in a different manner each time.

Note that, as described in Patent Document 1, an oil passage control valve that controls the supply / discharge state of hydraulic oil to / from the release chamber of the advance angle limiting mechanism and the supply / discharge state of hydraulic oil to the release chamber of the retardation limit mechanism It is also possible to control the advance angle limit pin and the retard angle limit pin by separate oil path control valves by providing separate oil path control valves for controlling. However, in this case, it is necessary to provide an oil passage control valve corresponding to each pin, and an increase in manufacturing cost is inevitable.

The present invention has been made in view of such circumstances, and an object thereof is to enable hydraulic oil to be supplied and discharged by a common oil passage control valve to each release chamber of the advance angle limiting mechanism and the retard angle limiting mechanism. An object of the present invention is to provide a variable valve operating apparatus for an internal combustion engine that can suppress the engine operating state from changing in a different manner every time the lock mechanism is switched from the locked state to the released state.

In order to achieve the above object, a variable valve operating apparatus for an internal combustion engine according to the present invention includes a first rotating body that rotates in synchronization with a crankshaft and a second rotating body that rotates in synchronization with a camshaft. And a hydraulically driven variable mechanism that changes the valve timing of the valve that is driven to open and close by the camshaft by the relative rotation generated between the two rotating bodies based on the hydraulic oil pressure, and the valve timing is the most retarded An advance that limits the relative rotation between the two rotating bodies so as to restrict the change to the advance side while allowing the change to the retard side relative to the specific time between the timing and the most advanced angle time. An angle limiting mechanism and a retard angle that restricts relative rotation between the rotating bodies so as to restrict the valve timing from changing to the retarded angle side while allowing the valve timing to change to the advanced angle side relative to the specific time. And the cooperation of these two restriction mechanisms And a locking mechanism for mechanically locking more the valve timing to the specific timing. Each of the advance angle limiting mechanism and the retard angle limiting mechanism includes a pin provided on one of the rotating bodies, a recess provided on the other of the rotating bodies and into which the pin fits, and the pin serving as the recess. A spring for urging the pin in a direction to be fitted into the pin, and a release chamber to which hydraulic oil for urging the pin in a direction in which the pin is removed from the recess is supplied. By reducing the hydraulic pressure of the chamber, the pins are fitted into the recesses to restrict relative rotation between the rotating bodies, while increasing the hydraulic pressure of the release chambers to the release hydraulic pressure. The pin is removed from each of the recesses, and the restriction on the relative rotation between the two rotating bodies is released. The advance angle limit mechanism and the retard angle limit mechanism are configured such that the supply / discharge state of the hydraulic oil with respect to the release chamber is controlled through a common oil passage control valve, and the variable valve apparatus includes the advance angle limit mechanism And the oil path control of the supply / discharge state of the hydraulic oil with respect to the release chambers of the two restriction mechanisms so that the pin of the same restriction mechanism is always pulled out before the other pin among the retardation restriction mechanisms. It has a control part which controls through a valve.

In this invention, the supply / discharge state of the hydraulic fluid to the release chambers of both limiting mechanisms is common so that the pin of the same limiting mechanism is always pulled out of the advance angle limiting mechanism and the retard angle limiting mechanism before the other pin. It is controlled through the oil passage control valve. Therefore, when the lock mechanism is switched from the locked state in which the valve timing is mechanically locked at a specific time to the released state, the pin of the same limiting mechanism is always removed from the recess first. That is, the pin of the same restriction mechanism is always released first. Therefore, when the lock mechanism is switched from the locked state to the released state, the change mode of the valve lift amount generated before and after the lock mechanism is suppressed from being different every time the switch is performed. As a result, when the lock mechanism is switched from the locked state to the released state, the engine operating state can be supplied and discharged with the common oil passage control valve to each release chamber of the advance angle limiting mechanism and the retard angle limiting mechanism. Can be prevented from changing in a different manner each time.

The control unit described above is configured so that a positive torque that causes a relative rotation between the two rotating bodies so that the valve timing changes to the retarded angle side during the increase period of the valve lift amount that acts on the camshaft. The first supply mode for supplying hydraulic oil to each release chamber and the valve timing change to the advance side so that the hydraulic pressure is raised and the pin of the advance angle limiting mechanism is removed from the recess. Further, a negative torque that causes a relative rotation between the two rotating bodies raises the hydraulic pressure in each release chamber during a decrease period of the valve lift amount that acts on the camshaft, so that the pin of the retardation limiting mechanism becomes the recess. The oil passage control valve is set so that the hydraulic oil is supplied to each release chamber in one of the second supply modes for supplying the hydraulic oil to each release chamber so as to be removed from the release chamber. Control.

Here, if a positive torque is applied to the camshaft when the lock mechanism is in the locked state, the pressing force between the inner wall of the recess into which the retard limit pin is inserted and the retard limit pin is more advanced. It becomes larger than the pressing force between the inner wall of the concave portion in which the pin is inserted and the advance angle limiting pin. On the other hand, if a negative torque is applied to the camshaft when the lock mechanism is in the locked state, the pressing force between the inner wall of the recess into which the advance limit pin is inserted and the advance limit pin is more retarded. Becomes larger than the pressing force between the inner wall of the recessed portion in which is inserted and the retard limit pin.

Therefore, when the oil passage control valve is controlled with the first supply mode for supplying the hydraulic oil so as to increase the hydraulic pressure of each release chamber during the increase period of the valve lift amount in which the positive torque acts on the camshaft, the advance angle The limit pin is released before the retard limit pin. On the other hand, when the oil passage control valve is controlled with the second supply mode for supplying the hydraulic oil so as to increase the hydraulic pressure of each release chamber during the decrease period of the valve lift amount in which the negative torque acts on the cam shaft, The limit pin is released before the advance angle limit pin.

In the above-described supply mode in which hydraulic oil is supplied to each release chamber so that the hydraulic pressure in the release chamber is raised and the pin of one of the limiting mechanisms is removed from the recess, positive torque or negative torque acts on the camshaft. In addition to starting the supply of hydraulic oil to each release chamber by the oil passage control valve during the predetermined period and increasing the hydraulic pressure of the release chamber to the release hydraulic pressure during this predetermined period, the oil is controlled before the predetermined period. It includes control for starting supply of hydraulic oil to the release chamber by the passage control valve to increase the hydraulic pressure in the release chamber to a pressure lower than the release hydraulic pressure, and increasing the hydraulic pressure in the release chamber to the release hydraulic pressure in a predetermined period.

Specifically, in the first supply mode, the supply of hydraulic oil to each release chamber is started during a period in which a positive torque is applied to the camshaft. It is preferable that supply of hydraulic oil to each release chamber is started during a period in which negative torque is acting on the camshaft.

When one of the advance angle limit mechanism and the retard angle limit mechanism is a first limit mechanism and the other is a second limit mechanism, the pins of the both limit mechanisms are inserted into the recesses, respectively. The change in the engine operating state that occurs when only the pin of the first limiting mechanism is switched to the state of being removed from the recess is that the pin of the both limiting mechanisms is inserted into the recess from the second limit. Only when the pin of the mechanism is switched to the state where it is removed from the recess, the control unit is configured so that the pin of the first limiting mechanism is always ahead of the pin of the second limiting mechanism. The oil passage control valve is controlled so as to be removed from the recess.

As described above, when the engine operating state changes as one pin of the advance angle limit mechanism and the retard angle limit mechanism is released, the advance angle limit pin is released before the delay angle limit pin. This is different from the change in the engine operating state and the change in the engine operating state when the retard limit pin is released before the advance limit pin. For this reason, when the change in the engine operating state when the advance limit pin is released before the retard limit pin is small, the oil passage control valve is controlled so that the advance limit pin is released first. On the other hand, if the change in the engine operating state when the retard limit pin is released before the advance limit pin is small, the oil passage control valve should be controlled so that the retard limit pin is released first. Is desirable. As a result, when the lock mechanism is switched from the locked state to the released state, it is possible to suppress a significant change in the engine operating state and to stabilize the engine operating state.

In particular, as a change in the engine operating state, when the change in engine output when the advance angle limit pin is released before the retard angle limit pin is small, the oil passage is set so that the advance angle limit pin is released first. While controlling the control valve, if the change in engine output when the retard limit pin is released before the advance limit pin is small, the oil passage control valve is set so that the retard limit pin is released first. It is desirable to control.

The variable mechanism changes the valve timing of the intake valve. When the valve timing of the intake valve is at the specific time, the intake valve opens when the piston of the internal combustion engine is near top dead center. In addition, it is preferable to close the valve on the retard side with respect to the bottom dead center.

An internal combustion engine in which the valve timing is set so that the intake valve when the lock mechanism is shifted from the locked state to the released state opens near the top dead center of the piston and closes on the retard side from the bottom dead center If so, the following tendencies generally exist. That is, when looking at the amount of intake air per hour flowing into the combustion chamber of the internal combustion engine when the intake valve is opened, the amount is larger during the period when the valve lift amount of the intake valve increases than during the period when the valve lift amount of the intake valve increases. This is because the negative pressure generated in the combustion chamber is smaller and the inertia force of the intake air is smaller in the period in which the valve lift amount increases than in the period in which the valve lift amount decreases, so the average flow velocity of the intake air flowing into the combustion chamber becomes smaller. . Therefore, in such an internal combustion engine, by adopting a configuration in which the oil passage control valve is controlled so that the retard limit pin is released before the advance limit pin, the valve lift amount is reduced and negative torque is applied to the camshaft. In the period during which the valve operates, in other words, in the period dominant in determining the intake air amount, it is possible to suppress the actual valve lift amount from being significantly lower than the original valve lift amount, thereby reducing the intake air amount. It is possible to suppress a decrease in engine output caused by the engine.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram which shows the variable valve operating apparatus of the internal combustion engine concerning embodiment of this invention, and an internal combustion engine provided with the same. The end view which shows the internal structure about the variable mechanism of the variable valve apparatus in the state which removed the sprocket of the variable mechanism. Schematic which shows the structure about the hydraulic-fluid channel | path of a hydraulic mechanism. FIG. 3 is a cross-sectional view showing a cross-sectional structure along the line AA in FIG. 2. (A) shows the corresponding relationship between the hydraulic oil supply state and each mode of the oil passage control valve in the variable valve operating device, and (b) shows the state of the variable mechanism and the limit pin and each mode of the oil passage control valve. The figure which shows a correspondence. FIG. 6 is a graph showing a difference between a valve lift amount when the lock mechanism is in a locked state and a valve lift amount when one of the advance angle limit pin and the retard angle limit pin is released first; ) Shows the change in the valve lift when only the retard limit pin is released, and (b) is a graph showing the change in the valve lift when only the advance limit pin is released. The timing chart which shows transition of the valve lift amount and the torque which acts on a cam shaft, and transition of each releasable period of an advance limit pin and a retard limit pin. The timing chart which shows the mode of the torque which acts on a cam shaft after engine starting, the state of the hydraulic fluid supply to a cancellation | release chamber, and the state of an advance angle limit pin and a retard angle limit pin. (A) is an end view showing the internal structure of a conventional variable mechanism, and (b) is a cross-sectional view showing a cross-sectional structure taken along line BB in (A). (A) is a graph showing the torque acting on the camshaft, (b) is a graph showing the valve lift when the lock mechanism is in the locked state, and (c) is the release of only the retard limit pin. 6 is a graph showing a change in the valve lift when the advance limit pin is released only. FIG.

Hereinafter, an embodiment in which the present invention is embodied as a variable valve operating apparatus for an internal combustion engine that changes the valve timing of an intake valve will be described with reference to FIGS.
As shown in FIG. 1, a crankshaft 12 that converts a reciprocating motion into a rotational motion is connected to a piston 11 that is accommodated in a cylinder of the internal combustion engine 10 so as to be able to reciprocate. A combustion chamber 13 is defined by the top surface of the piston 11 and the inner peripheral surface of the cylinder. An intake camshaft 22 that opens and closes the intake valve 21 and an exhaust camshaft 24 that opens and closes the exhaust valve 23 are provided on the upper portion of the internal combustion engine 10. On the other hand, an oil pan 15 that stores hydraulic oil is attached to the lower part of the internal combustion engine 10, and an oil pump 14 that is driven by the rotational force of the crankshaft 12 to assemble the hydraulic oil of the oil pan 15 is provided.

The variable valve operating device 20 is provided at the tip of the camshaft 22 to change the valve timing of the intake valve 21 and a specific intermediate timing (hereinafter referred to as the most advanced timing). And a hydraulic mechanism 60 that controls the hydraulic pressure of each oil chamber provided in the variable valve operating apparatus 20. The sprocket 31 of the variable mechanism 25 is drivingly connected to the crankshaft 12 through a timing chain (not shown). Further, the cover 30 of the variable mechanism 25 is provided on the surface opposite to the side on which the sprocket 31 is provided.

The hydraulic mechanism 60 includes a hydraulic oil passage 61 and an oil passage control valve (hereinafter referred to as “OCV (Oil Control Valve)”) 62. The hydraulic oil passage 61 includes a plurality of oil passages that supply the hydraulic oil of the oil pan 15 to each oil chamber, and a plurality of oil passages that return the hydraulic oil from each oil chamber to the oil pan 15. Further, the OCV 62 controls the supply / discharge state of the hydraulic oil with respect to each oil chamber provided in the variable valve apparatus 20. The hydraulic oil stored in the oil pan 15 functions as a hydraulic oil for lubricating each part of the internal combustion engine 10 in addition to a function as a hydraulic oil that generates a hydraulic pressure for driving the variable valve device 20. It has also.

The internal combustion engine 10 is provided with various sensors for detecting the operating state of the internal combustion engine 10. For example, such various sensors include a crank angle sensor 16 provided in the vicinity of the crankshaft 12 for detecting the crank angle and the engine rotational speed, and a cam provided in the vicinity of the camshaft 22 for detecting the position of the camshaft 22. There is an angle sensor 17 or the like. Signals output from these various sensors are taken into the control unit 18 that collectively controls various devices of the internal combustion engine 10.

The control unit 18 is provided with a storage device for storing calculation results of various controls, a function map used for the calculation, and the like in addition to the calculation device and the drive circuit. And this control part 18 detects the driving | running state of the internal combustion engine 10 based on the output signal from various sensors, and performs various control based on the detection result. In such variable valve timing control, the valve timing of the intake valve 21 is made to match the target valve timing suitable for the engine operating state by appropriately changing the spool position of the OCV 62 based on the engine operating state. To control this.

Next, the configuration of the variable mechanism 25 will be described with reference to FIG. FIG. 2 shows the internal structure of the variable mechanism 25 with the sprocket 31 removed. The sprocket 31, the housing 32, and the cover 30 described above are fixed to each other by bolts (not shown) and rotate integrally around the rotation axis of the cam shaft 22. The cover 30, the sprocket 31, and the housing 32 function as a first rotating body that is drivingly connected to the crankshaft 12. The cam shaft 22 and the housing 32 are assumed to rotate in the rotational direction RC shown in FIG.

The housing 32 is provided with three partition portions 34 extending radially inward. In addition, a vane rotor 33 that rotates about the same rotation axis as the housing 32 is accommodated in the housing 32 so as to be rotatable with respect to the housing 32. The vane rotor 33 includes a boss 33A coupled to the camshaft 22 so as to be integrally rotatable, and three vanes 33B projecting radially outward from the boss 33A. The boss 33 A is fixed to the end of the camshaft 22 by a center bolt 38. Three housing chambers 35 are defined by the three partition portions 34 of the housing 32 and the boss 33A of the vane rotor 33, and each housing chamber 35 is divided into an advance chamber 36 and a retard chamber 37 by each vane 33B. It is partitioned. The vane rotor 33 functions as a second rotating body that is drivingly connected to the cam shaft 22.

The variable mechanism 25 is provided with a lock mechanism 26 that holds the valve timing at a specific time suitable for engine start. The lock mechanism 26 includes an advance angle limiting mechanism 40 and a retard angle limiting mechanism 50 provided in each of the separate vanes 33B. The advance angle limiting mechanism 40 allows the housing 32 and the vane rotor 33 to rotate relative to each other in a manner that restricts the valve timing from changing to the advance angle side while allowing the valve timing to change from the specific time. Restrict. On the other hand, the retard angle limiting mechanism 50 allows the housing 32 and the vane rotor 33 to rotate relative to each other in a manner that restricts the valve timing from changing to the retarded angle side while allowing the valve timing to change from the specific timing. Limit that. Further, the advance angle limiting mechanism 40 and the retard angle limiting mechanism 50 are provided with a ratchet function that advances the valve timing stepwise from a timing that is behind the specific timing to a specific timing. The valve timing is held at a specific time by the cooperation of the advance angle limiting mechanism 40 and the retard angle limiting mechanism 50.

The OCV 62 described above is built in the center bolt 38. The variable mechanism 25 has a plurality of oil passages (operating oil passages 61) extending in the radial direction of the vane rotor 33 from the OCV 62 to the oil chambers of the advance chamber 36, the retard chamber 37, and the lock mechanism 26. Is provided.

Next, the configuration of the hydraulic oil passage 61 will be described with reference to FIGS. 2 and 3 together. The hydraulic oil passage 61 includes a supply oil passage 63, an advance oil passage 66, a retard oil passage 67, a release oil passage 68, and a discharge oil passage 69. The OCV 62 functions as a common oil passage control valve that controls the supply / discharge state of hydraulic fluid to the advance chamber 36 and the retard chamber 37 and the first release chamber 47 and the second release chamber 57.

The supply oil passage 63 communicates with the oil pump 14 and the OCV 62. In addition, the supply oil passage 63 has a first supply oil passage 64 connected to the advance / retard angle supply port 64P of the OCV 62 and a second supply oil connected to the release supply port 65P of the OCV 62. It branches off to the road 65.

The advance oil passage 66 communicates the advance port 66P of the OCV 62 and the advance chamber 36. The retard oil passage 67 communicates the retard port 67P of the OCV 62 and the retard chamber 37.
The release oil passage 68 is configured as an oil passage that is independent of the advance oil passage 66 and the retard oil passage 67 described above, and is used for releasing the first release chamber 47 and the OCV 62 of the advance angle limiting mechanism 40 in the middle. The first release oil passage 68A that communicates with the port 68P and the second release oil passage 68B that communicates between the second release chamber 57 of the retard restriction mechanism 50 and the release port 68P of the OCV 62 are branched. Yes.

The discharge oil passage 69 is connected to the discharge port 69 P of the OCV 62 and extends to the oil pan 15.
Next, a detailed configuration of the lock mechanism 26 will be described with reference to FIG. Hereinafter, the side where the cover 30 of the variable mechanism 25 is disposed in the axial direction of the camshaft 22 is referred to as “front end side ZA”, and the side where the sprocket 31 is disposed is referred to as “base end side ZB”.

The advance angle limiting mechanism 40 includes a cylindrical advance angle limit pin 41, a first recess 43 into which the advance angle limit pin 41 is fitted, and a first spring 42 that biases the advance angle limit pin 41 toward the distal end side ZA. And a first release chamber 47 into which hydraulic oil is supplied or discharged. The advance angle limiting pin 41, the first spring 42, and the first release chamber 47 are all provided in the vane 33B, while the first recess 43 is formed in the cover 30.

The advance angle limiting pin 41 reciprocates to the distal end side ZA and the proximal end side ZB in the vane hole 46 formed in the vane 33B, and a part of the advance angle limiting pin 41 projects to the outside of the vane 33B and fits into the first recess 43. . The vane hole 46 is partitioned by the advance limit pin 41 into a first spring chamber 48 on the base end side ZB and a first release chamber 47 on the front end side ZA. The first spring chamber 48 accommodates a first spring 42 that biases the advance limit pin 41 toward the distal end ZA. On the other hand, hydraulic oil is supplied to the first release chamber 47 through the first release oil passage 68A (see FIGS. 2 and 3) described above. When the hydraulic pressure in the first release chamber 47 rises higher than the first release hydraulic pressure P1, the advance limit pin 41 is released by the urging force based on this hydraulic pressure and moves to the proximal side ZB.

The first recess 43 has an arc shape along the circumferential direction of the cover 30. Specifically, the first concave portion 43 includes a first upper step portion 44 formed with a relatively shallow depth and a first lower step portion 45 formed with a relatively deep depth. . The first upper stage 44 is formed on the retard side with respect to the first lower stage 45.

The retard limit mechanism 50 includes a cylindrical retard limit pin 51, a second recess 53 into which the retard limit pin 51 is fitted, and a second spring 52 that biases the retard limit pin 51 toward the distal end ZA. And a second release chamber 57 into which hydraulic oil is supplied or discharged. The retard limit pin 51, the second spring 52, and the second release chamber 57 are all provided in the vane 33B, while the second recess 53 is formed in the cover 30.

The retard limit pin 51 reciprocates to the distal end side ZA and the proximal end side ZB in a vane hole 56 formed in the vane 33B, and a part of the retard angle limiting pin 51 protrudes outside the vane 33B and fits into the second recess 53. . The vane hole 56 is partitioned by the retard limit pin 51 into a second spring chamber 58 on the proximal end side ZB and a second release chamber 57 on the distal end side ZA. The second spring chamber 58 accommodates a second spring 52 that biases the retard limit pin 51 toward the distal end side ZA. On the other hand, hydraulic oil is supplied to the second release chamber 57 through the above-described second release oil passage 68B (see FIGS. 2 and 3). When the hydraulic pressure in the second release chamber 57 rises above the second release hydraulic pressure P2, the retard limit pin 51 moves to the base end side ZB by the urging force based on this hydraulic pressure.

The second recess 53 has an arc shape along the circumferential direction of the cover 30. Specifically, the second concave portion 53 includes a second upper step portion 54 formed with a relatively shallow depth and a second lower step portion 55 formed with a relatively deep depth. . The second upper step portion 54 is formed on the retard side with respect to the second lower step portion 55.

Advance limit pin 41, retard limit pin 51, first upper step 44 and first lower step 45 formed in first recess 43, and second upper step formed in second recess 53 54 and the second lower stage portion 55 function as a ratchet mechanism that gradually advances the valve timing to a specific time by an alternating torque acting on the cam shaft 22. That is, the first upper step portion 44 and the first lower step portion 45 formed in the first concave portion 43 have the delay of each step portion when the advance angle limiting pin 41 is fitted into these

step portions

44 and 45. The angle-side inner wall restricts the displacement of the limit pin 41 toward the retard side. On the other hand, the second upper step portion 54 and the second lower step portion 55 formed in the second recess 53 are restricted by the inner wall on the retard side of each step portion when the retard limit pin 51 is fitted. The displacement of the pin 51 toward the retard angle side is regulated.

Further, when the advance angle limiting pin 41 is fitted into the first lower step portion 45 and the retard limit pin 51 is fitted into the second lower step portion 55, the advance angle limit pin 51 is advanced by the inner wall 45B on the advance side of the first lower step portion 45. Displacement of the angle limiting pin 41 toward the advance side is restricted. In addition, displacement of the retard restriction pin 51 to the retard side is regulated by the retard inner wall 55A of the second lower step portion 55. As a result, the valve timing is locked at the specific time described above. FIG. 4 shows a state where the lock mechanism 26 is in a locked state and the valve timing is locked at a specific time.

Here, when only the retard limit pin 51 is released from the locked state of the lock mechanism 26 shown in FIG. 4, the advance limit pin 41 remains fitted in the first lower step 45 and the first lower step 45. Until it comes into contact with the inner wall 45A on the retarded side. In other words, the valve timing is allowed to change to the retard side from the specific time by an amount corresponding to the amount of displacement.

On the other hand, when only the advance limit pin 41 is released from the locked state of the lock mechanism 26, the retard limit pin 51 remains on the advance side of the second lower step portion 55 while being fitted into the second lower step portion 55. It can be displaced to the advance side until it comes into contact with the inner wall 55B. That is, the valve timing is allowed to change from the specific timing to the advance side by an amount corresponding to the amount of displacement.

Next, referring to FIG. 3 and FIG. 5 together, each mode (spool position) of the OCV 62 and the supply / discharge state of the hydraulic oil to the advance chamber 36, the retard chamber 37, and the

release chambers

47 and 57, The relationship will be described. Specifically, when the OCV 62 is switched between modes such as the first mode, the second mode, the third mode, the fourth mode, and the fifth mode through the control of the spool position of the OCV 62, the OCV 62 described above is controlled. The opening area of each port changes. Thereby, the supply / discharge state of the hydraulic oil to the advance chamber 36, the retard chamber 37, and the

release chambers

47 and 57 is changed.

In the first mode and the second mode, the advance / retard angle supply port 64P and the advance port 66P are communicated, and hydraulic oil is supplied from the first supply oil passage 64 to the advance oil passage 66. Further, the retard port 67P and the discharge port 69P are communicated, and the hydraulic oil is discharged from the retard oil passage 67 to the discharge oil passage 69. Further, the release port 68 P and the discharge port 69 P are communicated, and the hydraulic oil is discharged from the release oil passage 68 to the discharge oil passage 69.

Note that the communication area between the advance / retard angle supply port 64P and the advance port 66P in the second mode is set to be smaller than the communication area in the first mode. For this reason, the amount of hydraulic fluid supplied from the first supply oil passage 64 to the advance oil passage 66 in the second mode is smaller than that in the first mode.

When the OCV 62 is set to the first mode or the second mode, the variable mechanism 25 advances the valve timing. Further, the advance limit pin 41 and the retard limit pin 51 are urged in the direction of fitting into the first recess 43 and the second recess 53, respectively. The OCV 62 is set to the first mode when the engine is started, and is set to the second mode when the engine operation is stopped and during idle operation.

In the third mode, the release supply port 65P and the release port 68P are communicated with each other, and the first release chamber 47 and the first release port are connected from the second supply oil passage 65 through the release oil passage 68 (68A, 68B). The hydraulic oil is supplied to the two release chambers 57 respectively. As a result, the advance limit pin 41 and the retard limit pin 51 are released from the first recess 43 and the second recess 53, respectively, by the urging force based on the hydraulic pressure of the hydraulic oil supplied to the

release chambers

47 and 57. Then, the lock mechanism 26 is released. Further, the advance / retard angle supply port 64P and the advance angle port 66P are communicated, and hydraulic oil is supplied from the first supply oil passage 64 to the advance chambers 36 via the advance oil passage 66. Further, the retard port 67P and the discharge port 69P are communicated, and the hydraulic oil in each retard chamber 37 is discharged from the retard oil passage 67 through the discharge oil passage 69. As a result, the valve timing is advanced. That is, the OCV 62 is set to the third mode when executing the advance control of the valve timing.

In the fourth mode, the release supply port 65P and the release port 68P are communicated with each other, and the first release chamber 47 and the first release port are connected from the second supply oil passage 65 through the release oil passage 68 (68A, 68B). The hydraulic oil is supplied to the two release chambers 57 respectively. As a result, the advance limit pin 41 and the retard limit pin 51 are released from the first recess 43 and the second recess 53, respectively, by the urging force based on the hydraulic pressure of the hydraulic oil supplied to the

release chambers

47 and 57. Then, the lock mechanism 26 is released. Further, the advance port 66P and the retard port 67P are closed. For this reason, both the supply and discharge of the hydraulic fluid to each advance chamber 36 through the advance oil passage 66 and the supply and discharge of the hydraulic oil to each retard chamber 37 through the retard oil passage 67 are stopped. The As a result, the valve timing is maintained. The OCV 62 is set to the fourth mode when the valve timing is maintained at the target valve timing and when the lock mechanism 26 is switched from the locked state to the released state.

In the fifth mode, the release supply port 65P and the release port 68P are communicated with each other, and the first release chamber 47 and the first release chamber 65 are connected from the second supply oil passage 65 through the release oil passage 68 (68A, 68B). The hydraulic oil is supplied to the two release chambers 57 respectively. As a result, the advance limit pin 41 and the retard limit pin 51 are released by the urging force based on the hydraulic pressure of the hydraulic oil supplied to the

release chambers

47 and 57, and the lock mechanism 26 is released. Further, the advance port 66P and the discharge port 69P are communicated, and the hydraulic oil in each advance chamber 36 is discharged from the advance oil passage 66 through the discharge oil passage 69. Further, the advance / retard angle supply port 64P and the retard angle port 67P are communicated, and hydraulic oil is supplied from the first supply oil path 64 to the respective retard angle chambers 37 via the retard angle oil path 67. As a result, the valve timing is retarded. That is, the OCV 62 is set to the fifth mode when executing the valve timing retardation control.

Next, the operation of the variable valve gear 20 will be described.
When the crankshaft 12 rotates as the engine operates, the driving force is transmitted to the variable mechanism 25 via a timing chain (not shown), and the camshaft 22 rotates together with the variable mechanism 25. Thus, the intake valve 21 is opened and closed by a cam (not shown) provided on the cam shaft 22.

Further, when the supply / discharge state of the hydraulic fluid to the advance chamber 36 and the retard chamber 37 of the variable mechanism 25 is controlled through the OCV 62, the vane 33 B is formed in the storage chamber 35 based on the hydraulic pressure of the advance chamber 36 and the retard chamber 37. Displace. Thereby, the relative rotational position of the vane rotor 33 with respect to the sprocket 31 and the housing 32, that is, the relative rotational position of the cam shaft 22 with respect to the crankshaft 12 is changed, and the valve timing of the intake valve 21 is changed.

Specifically, when the OCV 62 is set to the above-described first mode, second mode, or third mode, the vane rotor 33 rotates relative to the housing 32 in the advance side direction. Is advanced. When the vane 33B comes into contact with the inner wall on the advance side of the retard chamber 37, the valve timing becomes the most advanced timing. When the valve timing is advanced in this manner, the valve overlap between the exhaust valve 23 and the intake valve 21 increases, so that the intake charging efficiency is increased and the output of the internal combustion engine 10 can be improved.

Further, when the OCV 62 is set to the fifth mode, the valve timing is retarded when the vane rotor 33 rotates relative to the housing 32 in the retard angle direction. When the vane 33B comes into contact with the retarded side inner wall of the advance chamber 36, the valve timing becomes the most retarded timing. When the valve timing is retarded from the specific timing in this way, the engine operation in the combustion cycle in which the closing timing of the intake valve 21 is retarded relatively larger than the bottom dead center BDC of the piston 11, so-called “Atkinson cycle”, is performed. Will be made. Thereby, an expansion ratio can be made larger than a compression ratio, and a fuel consumption can be improved.

By the way, when the valve timing is set to the most retarded timing at the start of the internal combustion engine 10, the compression ratio is not sufficient, so that the engine cannot be started, or a long time is required for starting the engine, etc. The engine startability will be deteriorated. Thus, in the present embodiment, when the engine is started, the lock mechanism 26 is switched to the locked state at the time of engine stop request so that the valve timing is locked at a specific time that is a valve timing suitable for engine start.

Generally, the engine stop request is executed after the internal combustion engine 10 shifts to idle operation. Therefore, when the internal combustion engine 10 shifts during idle operation, the OCV 62 is controlled so that the lock mechanism 26 is switched to the locked state. That is, when the valve timing is on the retard side with respect to the specific timing, the OCV 62 is set to the second mode. On the other hand, when the valve timing is more advanced than the specific timing, the OCV 62 is once set to the fifth mode, and the valve timing is retarded. Thereafter, the OCV 62 is set to the second mode. Accordingly, the valve timing is gradually advanced, and the hydraulic oil is discharged from the first release chamber 47 and the second release chamber 57, respectively. When the hydraulic oil is discharged from the first release chamber 47 of the advance angle limiting mechanism 40 and the hydraulic pressure in the first release chamber 47 becomes lower than the first release hydraulic pressure P1, the urging force of the first spring 42 is applied. The advance angle limiting pin 41 is fitted into the first recess 43 (first lower step 45). At the same time, when the hydraulic oil is discharged from the second release chamber 57 of the retard restriction mechanism 50 and the hydraulic pressure in the second release chamber 57 is lower than the second release hydraulic pressure P2, the second spring 52 is attached. By being energized by the force, the retard limit pin 51 is fitted into the second recess 53 (second lower step portion 55). As a result, the advance angle limit pin 41 is displaced toward the advance side by the advance side inner wall 45B of the first lower step 45, and the retard angle limit pin 51 is displaced toward the retard side by the second angle. The lock mechanism 26 is locked by being regulated by the inner wall 55A on the retard side of the lower step portion 55. That is, the valve timing is locked at a specific time.

After that, when the internal combustion engine 10 is requested to start, cranking is started with the valve timing locked at a specific time. When the engine start is started when the valve timing is set to a specific timing in this way, as shown in FIG. 6, when the piston 11 is at the top dead center (exhaust top dead center or intake top dead center) TDC. The intake valve 21 is opened at the same time, and the valve is closed on the retard side from the bottom dead center (intake bottom dead center) BDC. Further, the valve overlap between the exhaust valve 23 and the intake valve 21 is kept small. As a result, the compression ratio becomes a value suitable for starting the engine, the combustibility at the time of starting the engine is stabilized, and the internal combustion engine 10 can be started well.

When the release condition for releasing the valve timing from the specific time is established after the engine is started, the lock mechanism 26 is switched to the release state. Specifically, when the OCV 62 is set to the fourth mode, the hydraulic oil is supplied to the first release chamber 47 and the second release chamber 57 through the release oil passage 68, respectively. As described above, since the release oil passage 68 is branched into the first release oil passage 68A and the second release oil passage 68B in the middle thereof, the hydraulic oil supplied to the release oil passage 68 is These

release oil passages

68A and 68B are equally supplied to both

release chambers

47 and 57.

By the way, when the lock mechanism 26 is switched from the locked state to the released state in this way, the advance angle limit pin 41 and the retard angle limit pin 51 are rarely released at the same timing. Either one of the pins 41 and 51 is released first.

The engine operating state changes when the advance angle limit pin 41 is released before the retard angle limit pin 51 and the engine when the delay angle limit pin 51 is released before the advance angle limit pin 41. It is different from the change of the driving state. Specifically, under the situation where each hydraulic pressure of the advance chamber 36 and the retard chamber 37 is not sufficiently increased, one of the advance angle limit pin 41 and the retard angle limit pin 51 is not recessed. When the other is released first while being fitted in the valve, the valve lift amount changes as follows according to the pins 41 and 51 released earlier.

FIG. 6A shows a change in the valve lift amount when the retard limit pin 51 is released before the advance limit pin 41. As shown in the figure, when the retard limit pin 51 is released first, the advancement is performed during the period in which the lift amount of the intake valve 21 increases and the positive torque acts on the camshaft 22. While the angle limit pin 41 is fitted in the first lower step portion 45, the advance angle limit pin 41 is displaced toward the retard side until it contacts the inner wall 45A on the retard side of the first lower step portion 45 (FIG. 4). reference). When the vane rotor 33 and the housing 32 rotate relative to each other in the direction in which the valve timing is retarded in this way, the lift change of the intake valve 21 is delayed as compared with the case where the lock mechanism 26 is in the locked state (shown by a broken line). The lift amount decreases. Therefore, compared with the case where the lock mechanism 26 is in the locked state, the engine output is reduced by reducing the amount of intake air introduced into the combustion chamber 13. On the other hand, in the period in which the lift amount of the intake valve 21 is reduced and the negative torque is acting on the camshaft 22, the advance limit pin 41 is the inner wall 45B on the advance side of the first lower stage 45. Therefore, the displacement of the valve is restricted, so that the valve lift amount changes as in the case where the lock mechanism 26 is in the locked state.

On the other hand, FIG. 6B shows a change in the valve lift when the advance limit pin 41 is released before the retard limit pin 51. As shown in the figure, when the advance angle limiting pin 41 is released first, it is delayed in a period in which the lift amount of the intake valve 21 is reduced and negative torque is acting on the camshaft 22. The angle limiting pin 51 is displaced toward the advance side until it contacts the inner wall 55B on the advance side of the second lower step portion 55 while being fitted in the second lower step portion 55 (see FIG. 4). Thus, when the vane rotor 33 and the housing 32 rotate relative to each other in the direction in which the valve timing advances, the lift change of the intake valve 21 becomes faster than when the lock mechanism 26 is in the locked state (illustrated by a broken line). The valve lift is reduced. Therefore, compared with the case where the lock mechanism 26 is in the locked state, the engine output is reduced by reducing the amount of intake air introduced into the combustion chamber 13. On the other hand, in the period in which the lift amount of the intake valve 21 is increased and the positive torque is acting on the camshaft 22, the retard limit pin 51 is connected to the inner wall 55A on the retard side of the second lower stage portion 55. Therefore, the displacement of the valve is restricted, so that the valve lift amount changes as in the case where the lock mechanism 26 is in the locked state.

Here, when the valve timing of the intake valve 21 is at a specific time, the valve timing is set so that the intake valve 21 opens at the top dead center TDC and closes on the retard side from the bottom dead center BDC. In the internal combustion engine 10, when the amount of intake air per hour flowing into the combustion chamber 13 when the intake valve 21 is opened, the amount is reduced during the period when the valve lift amount of the intake valve 21 is increased. Becomes larger. This is because the negative pressure generated in the combustion chamber 13 is smaller and the inertial force of the intake air is smaller in the period in which the valve lift amount increases than in the period in which the valve lift amount decreases, so the average flow velocity of the intake air flowing into the combustion chamber 13 becomes smaller. It is. Therefore, the period in which the valve lift amount decreases and the negative torque acts on the camshaft becomes a dominant period in determining the intake air amount. Therefore, the change in the engine operating state that occurs before and after switching from the state in which the lock mechanism 26 is in the locked state to the state in which only the retard limit pin 51 is released first (FIG. 6A) is greater. This is smaller than the change in the engine operating state (FIG. 6B) that occurs before and after the state where only the advance angle limiting pin 41 is switched from the locked state to the previously released state. In other words, the degree of decrease in engine output that occurs before and after switching from the state in which the lock mechanism 26 is in the locked state to the state in which only the retard limit pin 51 is released first (FIG. 6 (a)), the lock mechanism 26 is locked. This is smaller than the degree of reduction in engine output (FIG. 6B) that occurs before and after switching from the state where only the advance angle limiting pin 41 is released to the state previously released.

Next, referring to FIG. 7, the transition of the valve lift amount of the intake valve 21 and the torque acting on the camshaft 22 and the transition of the releasable period of each of the advance limit pin 41 and the retard limit pin 51 are described. explain. FIG. 7 shows an example in which three cams are formed on the cam shaft 22 and the valve opening period of the intake valve 21 that is driven to open and close by the cams is 240 ° CA. The transition of the acting torque is shown respectively.

Here, when the lock mechanism 26 is in the locked state, if a positive torque acts on the camshaft 22 as the valve lift amount increases, a force is exerted in a direction in which the vane rotor 33 is displaced toward the retard side with respect to the cover 30. Act. For this reason, the pressing force between the retard-side inner wall 55A of the second lower step portion 55 and the retard limit pin 51 is such that the advance side inner wall 45B and the advance limit pin 41 of the first lower step portion 45 It becomes larger than the pressing force. That is, a larger pressing force acts on the retard limit pin 51 than the advance limit pin 41. Therefore, when the OCV 62 is controlled with the first supply mode for supplying the hydraulic oil so as to increase the hydraulic pressure in the

release chambers

47 and 57 during the increase period of the valve lift amount in which the positive torque acts on the camshaft 22, the OCV 62 advances. The angle limit pin 41 is released before the retard limit pin 51.

On the other hand, when the lock mechanism 26 is in the locked state, if a negative torque acts on the camshaft 22 as the valve lift amount decreases, a force is applied in a direction in which the vane rotor 33 is displaced toward the advance side with respect to the cover 30. Works. Therefore, the pressing force between the advance side inner wall 45B of the first lower step portion 45 and the advance limit pin 41 is such that the retard side inner wall 55A and the retard limit pin 51 of the second lower step portion 55 are It becomes larger than the pressing force. In other words, a larger pressing force acts on the advance limit pin 41 than on the retard limit pin 51. Accordingly, when the OCV 62 is controlled with the second supply mode in which the hydraulic oil is supplied so as to increase the hydraulic pressure of the

release chambers

47 and 57 during the period in which the valve lift amount on which the negative torque acts on the camshaft 22 is reduced, the OCV 62 is delayed. The angle limit pin 51 is released before the advance angle limit pin 41.

Therefore, in the present embodiment, the OCV 62 is controlled with the second supply mode. Specifically, the OCV 62 is set to the fourth mode during a period in which a negative torque is acting on the camshaft 22, whereby the hydraulic oil is supplied to the first release chamber 47 and the second release chamber 57. Supply is performed.

Next, with reference to FIG. 8, the relationship between the supply state of the hydraulic fluid to the

release chambers

47 and 57 and the states of the advance angle limit pin 41 and the retard angle limit pin 51 at the time of starting the engine will be described.
After the internal combustion engine 10 is started at the timing T1, when the negative torque starts to act on the camshaft 22 at the timing T2, the OCV 62 is set to the fourth mode, and the first release chamber 47 and the second release are set. Supply of hydraulic oil to the chamber 57 is started. Since the period during which negative torque is acting on the camshaft 22 in this way is the period during which the retard limit pin 51 can be released, the retard limit pin 51 comes before the advance limit pin 41 at timing T3. Canceled. Thereafter, when a positive torque starts to act on the camshaft 22 at timing T4, the period in which the positive torque is acting on the camshaft 22 is a period in which the advance limit pin 41 can be released. At timing T5, the advance angle limit pin 41 is released. As a result, the lock mechanism 26 is released. Thereafter, the valve timing of the intake valve 21 is set to a target valve timing suitable for the engine operating state through the control of the OCV 62.

According to this embodiment described above, the following effects can be obtained.
(1) Hydraulic oil for the

release chambers

47 and 57 so that the same pin among the pins 41 and 51 of the advance angle limiting mechanism 40 and the retard angle limiting mechanism 50 is always released before the other pins 41 and 51. Are controlled through the common OCV 62. Therefore, when the lock mechanism 26 is switched from the locked state to the released state, the same pins 41 and 51 are always released first. Therefore, when the lock mechanism 26 is switched from the locked state to the released state, the change mode of the valve lift amount that occurs before and after the lock mechanism 26 is suppressed from being different every time the switch is performed. Thus, when the lock mechanism 26 is switched from the locked state to the released state while allowing the hydraulic oil to be supplied and discharged by the common OCV 62 to the

release chambers

47 and 57 of the advance angle limiting mechanism 40 and the retard angle limiting mechanism 50. It is possible to suppress the engine operating state from changing in a different manner each time.

(2) In the internal combustion engine 10, the retard limit pin 51 is more advanced than the advance limit pin 41 compared to the change in the engine operating state when the advance limit pin 41 is released before the retard limit pin 51. The change in the engine operating state when it is first released is smaller. Therefore, the OCV 62 is controlled so that the retard limit pin 51 is released first. Thereby, when the lock mechanism 26 is switched from the locked state to the released state, it is possible to suppress a significant change in the engine operating state and to stabilize it.

(3) Further, as described above, since the retard limit pin 51 is released before the advance limit pin 41, in other words, a period during which the valve lift amount decreases and negative torque acts on the camshaft 22. During the dominant period for determining the intake air amount, it is possible to suppress the actual valve lift amount from greatly decreasing from the original valve lift amount, and to reduce the engine output due to the decrease in the intake air amount. It will be possible to suppress.

(4) The variable valve operating apparatus 20 is provided with a single OCV 62, and hydraulic fluid for the advance chamber 36, the retard chamber 37, the first release chamber 47, and the second release chamber 57 is provided by this OCV 62. The supply / discharge state is controlled. Therefore, the number of parts can be reduced and the manufacturing cost of the variable valve operating apparatus 20 can be reduced as compared with a configuration in which a plurality of OCVs are provided.

(Other embodiments)
The variable valve operating apparatus for an internal combustion engine according to the present invention is not limited to the configuration exemplified in the above-described embodiment, and may be implemented as, for example, the following form obtained by appropriately modifying this embodiment. it can.

In the above embodiment, the OCV 62 is set to the fourth mode during the period in which the negative torque is acting on the camshaft 22 in order to release the retard limit pin 51 before the advance limit pin 41. An example is shown in which the supply of hydraulic oil to the first release chamber 47 and the second release chamber 57 is started. On the other hand, the hydraulic pressures of the first release chamber 47 and the second release chamber 57 are changed from the first release hydraulic pressure P1 and the second release hydraulic pressure P2 during a period in which a positive torque is applied to the camshaft 22. Alternatively, the pressure may be increased to a low value, and after that, after the negative torque starts to act on the camshaft 22, it may be increased to the release hydraulic pressure. Note that it is desirable to determine the supply start timing of the hydraulic oil to the first release chamber 47 and the second release chamber 57 in consideration of the responsiveness of the OCV 62, the viscosity of the hydraulic oil, and the like. Even in this case, the above-described effects can be achieved.

-The relationship between each mode of OCV62 shown in the said embodiment and the supply-and-discharge state of the hydraulic fluid in the hydraulic fluid passage 61 is an example, and can be changed suitably.
In the above embodiment, the OCV 62 is set to the fourth mode during the period in which the negative torque is acting on the camshaft 22 to release the retard limit pin 51 before the advance limit pin 41, Thereafter, an example in which the advance angle limiting pin 41 is released while the mode of the OCV 62 is maintained in the fourth mode is shown. On the other hand, the mode of the OCV 62 may be changed after the retard limit pin 51 is released. For example, after only the retard limit pin 51 is released, the OCV 62 may be set to the fifth mode and the advance angle limit pin 41 may be released. That is, when the OCV 62 is set to the fifth mode and the valve timing retardation control is started, the pressing force between the advance side inner wall 45B of the first lower stage 45 and the advance limit pin 41 decreases. . In addition, since the hydraulic oil is supplied to the

release chambers

47 and 57, the advance limit pin 41 can be released. Furthermore, after the lock mechanism 26 switches from the locked state to the released state, the valve timing can be changed more quickly on the retard side than the specific time.

In the above embodiment, the OCV 62 is set to the fourth mode during the period in which the negative torque is acting on the camshaft 22 in order to release the retard limit pin 51 before the advance limit pin 41. In addition, the example in which the advance angle limiting pin 41 is released during the period in which the positive torque is applied to the camshaft 22 by maintaining the fourth mode is shown. On the other hand, it is also possible to adopt a configuration in which the pins 41 and 51 are released with a longer interval than the release intervals of the pins 41 and 51 executed in the embodiment. For example, the hydraulic oil is not supplied to the

release chambers

47 and 57 after the OCV 62 is set to the fourth mode and the retard limit pin 51 is released during a period in which negative torque is acting on the camshaft 22. The OCV 62 is once set to the first mode or the second mode, and then the OCV 62 is set to the fourth mode again during a period in which the positive torque is acting on the camshaft 22 to advance the advance angle limiting pin 41. May be canceled.

In the above embodiment, the example in which the second supply mode is adopted as the hydraulic oil supply mode by the OCV 62 is shown. In contrast, the first release chamber has a first supply mode in which hydraulic oil is supplied so as to increase the hydraulic pressure of each

release chamber

47, 57 during the increase period of the valve lift amount in which positive torque acts on the camshaft 22. The OCV 62 may be controlled such that hydraulic oil is supplied to the 47 and the second release chamber 57. For example, a change in the engine operating state that occurs before and after the advance angle limit pin 41 is switched from a state in which the lock mechanism 26 is in a locked state to a state in which the advance angle limit pin 41 is released before the delay angle limit pin 51 causes the delay angle limit pin 51 to advance. In an internal combustion engine that is smaller than the change in the engine operating state that occurs before and after switching to the released state before the angle limiting pin 41, the OCV 62 is controlled with the first supply mode described above, whereby the advance angle limiting pin 41 is controlled. May be canceled first. Thereby, when the lock mechanism 26 is switched from the locked state to the released state, it is possible to suppress a significant change in the engine operating state and to stabilize it.

The opening timing and closing timing of the intake valve when the valve timing of the intake valve is at a specific timing are not limited to those exemplified in the above embodiment, but may be engine demand characteristics such as engine output characteristics and fuel consumption characteristics. It can also be changed accordingly. Then, based on the opening timing and closing timing of the intake valve thus set, the engine operating state should be canceled first when the lock mechanism 26 is shifted from the locked state to the released state. By determining the pins 41 and 51, it is possible to achieve operational effects according to the operational effects shown in the above (1), (2), and (4).

In the above embodiment, in consideration of the change in the engine operating state that occurs before and after the lock mechanism 26 is switched from the locked state to the released state of one of the pins 41, 51, the advance angle limiting pin 41 and The example in which the pin to be released first among the retard limit pins 51 is determined is shown. However, even if such a change in the engine operating state is not taken into consideration, the hydraulic oil supply / discharge state is controlled to release the advance angle limit pin 41 and the retard angle limit pin 51 at different timings. Each effect shown in 1) and (4) can be exhibited.

In the above embodiment, a plurality of

step portions

44, 45, 54, and 55 are formed in the first recess 43 of the advance angle limiting mechanism 40 and the second recess 53 of the retard angle limiting mechanism 50, respectively. An example in which the angle limiting mechanism 40 and the retardation limiting mechanism 50 function also as a ratchet mechanism is shown. However, it is also possible to employ a configuration in which a plurality of steps are not formed in the first recess 43 and the second recess. Even in this case, the advance angle limit pin 41 is fitted into the first recess 43 and the retard angle limit pin 51 is fitted into the second recess 53, so that the valve timing is locked and locked at a specific time. The mechanism 26 is locked. In addition, the functions and effects shown in (1) to (4) above can be achieved.

In each of the above embodiments, an example in which the ratchet mechanism is configured as a mechanism for advancing the valve timing that is on the retard side with respect to the specific time has been shown. On the other hand, the ratchet mechanism may be configured to also have a mechanism for retarding the valve timing that is on the more advanced side than the specific time.

In the above-described embodiment, the example in which the supply / discharge state of the hydraulic oil with respect to each oil chamber of the variable valve apparatus 20 is controlled by the single OCV 62 has been described. On the other hand, an oil passage control valve for controlling the supply / discharge state of hydraulic oil to / from the advance chamber 36 and the retard chamber 37 of the variable mechanism 25, and the first release chamber 47 and the second release chamber 57 of the lock mechanism 26. An oil passage control valve for controlling the supply / discharge state of the hydraulic oil with respect to the oil may be provided separately. Even in this case, the effects shown in the above (1) to (3) can be achieved.

In the above embodiment, an example in which the advance angle limiting mechanism 40 and the retard angle limiting mechanism 50 are provided in the respective vanes 33B has been described. On the other hand, a configuration in which the advance angle limiting mechanism 40 and the retard angle limiting mechanism 50 are provided in the same vane 33B may be employed.

In the above embodiment, an example in which the

concave portions

43 and 53 are formed in the cover 30 is shown, but the

concave portions

43 and 53 may be formed in the sprocket 31.
In the above embodiment, an example in which both the advance angle limiting pin 41 and the retard angle limiting pin 51 are provided in the vane rotor 33 while the first recess 43 and the second recess 53 are both provided in the cover 30 is shown. . On the other hand, a configuration in which both the pins 41 and 51 are provided in the cover 30 and the

recesses

43 and 53 are both provided in the vane rotor 33 may be adopted. Moreover, you may employ | adopt the structure by which the pins 41 and 51 are provided in a mutually different rotary body. For example, the advance angle limit pin 41 is provided on the vane rotor 33 and the first recess 43 is provided on the cover 30, while the retard limit pin 51 is provided on the cover 30 and the second recess 53 is provided on the vane rotor 33. You may do it.

In the above embodiment, an example in which the sprocket 31 is drivingly connected to the crankshaft 12 and the vane rotor 33 is drivingly connected to the camshaft 22 has been described. However, the variable valve gear 20 may be configured such that the sprocket 31 is drivingly connected to the camshaft 22 and the vane rotor 33 is drivingly connected to the crankshaft 12. Even in this case, the above-described effects can be achieved.

In the above-described embodiment, an example in which the valve timing of the intake valve 21 is changed is shown as an example of the variable valve operating device 20, but the present invention is realized as a variable valve operating device that changes the valve timing of the exhaust valve 23. It is also possible. The present invention can also be applied to each of a variable valve operating device that changes the valve timing of the intake valve 21 and a variable valve operating device that changes the valve timing of the exhaust valve 23.

DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 11 ... Piston, 12 ... Crankshaft, 13 ... Combustion chamber, 14 ... Oil pump, 15 ... Oil pan, 16 ... Crank angle sensor, 17 ... Cam angle sensor, 18 ... Control part, 20 ... Variable motion Valve device, 21 ... intake valve, 22, 200 ... (for intake) camshaft, 23 ... exhaust valve, 24 ... (for exhaust) camshaft, 25, 100 ... variable mechanism, 26, 110 ... lock mechanism, 30 ... cover (First rotating body), 31, 101 ... sprocket (first rotating body), 32, 102 ... housing (first rotating body), 33, 103 ... vane rotor (second rotating body), 33A ...

boss

33B, 103A ... vane, 34 ... compartment, 35, 105 ... storage chamber, 36, 106 ... advance chamber, 37, 107 ... retard chamber, 38 ... center bolt, 40 ... advance limit mechanism, 41 ... advance Angle limit pin, 2 ... 1st spring, 43 ... 1st recessed part, 44 ... 1st upper step part, 45 ... 1st lower step part, 45A, 55A ... Inner wall on the retard side, 45B, 55B ... Inner wall on the advance side, 46, 56 ... vane hole, 47 ... first release chamber, 48 ... first spring chamber, 50 ... retard angle limiting mechanism, 51 ... retard angle limiting pin, 52 ... second spring, 53 ... second recess. 54 ... second upper step portion, 55 ... second lower step portion, 57 ... second release chamber, 58 ... second spring chamber, 60 ... hydraulic mechanism, 61 ... hydraulic oil passage, 62 ... OCV (oil passage) Control valve), 63 ... supply oil passage, 64 ... first supply oil passage, 64P ... advance delay angle supply port, 65 ... second supply oil passage, 65P ... release supply port, 66 ... advance angle oil passage, 66P ... Advance angle port, 67 ... Delay angle oil path, 67P ... Delay angle port, 68 ... Release oil path, 68A ... First release oil path, 68B ... Second release oil path, 6 P ... release port, 69 ... discharge oil passage, 69P ... exhaust port, 111 ... pin, 112 ... recessed portion, 113 ... spring 114 ... release chamber.

Claims

A variable valve operating device for an internal combustion engine,
A valve timing of a valve that has a first rotating body that rotates in synchronization with the crankshaft and a second rotating body that rotates in synchronization with the camshaft and that is driven to open and close by the camshaft is determined by operating oil. A hydraulically driven variable mechanism that changes by relative rotation generated between the two rotating bodies based on the hydraulic pressure of
The valve timing between the rotating bodies is regulated so as to restrict the valve timing from changing to the advance side while allowing the valve timing to change from the specific timing between the most retarded timing and the most advanced timing. An advance angle limiting mechanism that limits relative rotation, and a relative angle between the two rotating bodies so as to restrict the valve timing from changing to the retarded angle side while allowing the valve timing to change to the advanced angle side from the specific time. A delay angle limiting mechanism that limits rotation, and a lock mechanism that mechanically locks the valve timing at the specific time by the cooperation of both the limiting mechanisms,
Each of the advance angle limiting mechanism and the retard angle limiting mechanism includes a pin provided on one of the rotating bodies, a recess provided on the other of the rotating bodies and into which the pin fits, and the pin serving as the recess. A spring for urging the pin in a direction to be fitted into the pin, and a release chamber to which hydraulic oil for urging the pin in a direction in which the pin is removed from the recess is supplied. By reducing the hydraulic pressure of the chamber, the pins are fitted into the recesses to restrict relative rotation between the rotating bodies, while increasing the hydraulic pressure of the release chambers to the release hydraulic pressure. It is configured to release the restriction on the relative rotation between the two rotating bodies by removing the pin from each recess,
The advance angle limiting mechanism and the retard angle limiting mechanism are such that the supply / discharge state of the hydraulic oil to the release chamber is controlled through a common oil passage control valve,
The supply / discharge state of the hydraulic fluid to the release chambers of the two restriction mechanisms so that the pin of the same restriction mechanism is always pulled out of the advance restriction mechanism and the retard restriction mechanism before the other pin. A variable valve operating apparatus for an internal combustion engine, comprising: a control unit that controls the engine through the oil passage control valve.
The controller controls the hydraulic pressure in each release chamber during an increase period of a valve lift amount in which a positive torque that causes relative rotation between the two rotating bodies acts on the camshaft so that the valve timing changes to the retard side. So that the pin of the advance limit mechanism is pulled out of the recess, and the valve timing is changed to the advance side. A negative torque that causes a relative rotation between the two rotating bodies increases the hydraulic pressure in each release chamber during a period in which the valve lift amount acting on the camshaft is reduced, so that the pin of the retardation limiting mechanism is released from the recess. The oil passage control valve is controlled so that the hydraulic oil is supplied to each release chamber according to any one of the second supply modes for supplying the hydraulic oil to each release chamber so as to be removed. The internal combustion engine according to claim 1 Variable valve gear.
The first supply mode starts supply of hydraulic oil to the release chambers during a period in which a positive torque is acting on the cam shaft, and the second supply mode is the cam shaft. The variable valve operating apparatus for an internal combustion engine according to claim 2, wherein supply of hydraulic oil to each of the release chambers is started during a period in which negative torque is applied to the internal combustion engine.
When one of the advance limit mechanism and the retard limit mechanism is a first limit mechanism and the other is a second limit mechanism,
The change in the engine operating state that occurs when only the pins of the first limiting mechanism are removed from the recesses from the state where the pins of the limiting mechanisms are respectively inserted into the recesses, Smaller than that when only the pin of the second restriction mechanism is switched from the state where the pin of the mechanism is inserted into the recess, respectively,
The control unit controls the oil passage control valve so that the pin of the first limiting mechanism is always withdrawn from the recess first before the pin of the second limiting mechanism. A variable valve operating apparatus for an internal combustion engine according to claim 1.
The variable valve operating apparatus for an internal combustion engine according to claim 4, wherein the engine operating state is an engine output.
The said control part controls the said oil path control valve so that the said pin of the said retard restriction mechanism may always be extracted from the said recessed part always before the said pin of the said advance restriction mechanism. The variable valve operating apparatus for an internal combustion engine.
The said control part controls the said oil path control valve so that the said pin of the said advance angle limiting mechanism may always be extracted from the said recessed part ahead of the said pin of the said retard angle limiting mechanism. The variable valve operating apparatus for an internal combustion engine.
The variable mechanism changes the valve timing of the intake valve,
The intake valve is opened when the piston of the internal combustion engine is in the vicinity of the top dead center and closed on the retard side from the bottom dead center when the valve timing of the intake valve is at the specific time. 6. A variable valve operating apparatus for an internal combustion engine according to 6.