JP2002180807A - Variable valve timing mechanism of valve system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable valve timing mechanism capable of performing both intake-exhaust simultaneous ignition timing log control and intake ignition timing advance control, and capable of surely holding an intake control vane rotor in an initial position. SOLUTION: A rotor housing 3 for transmitting rotation of a crankshaft is relatively rotatably installed on an intake side camshaft 2, intake side-exhaust side vane rotors 4 and 5 are relatively rotatably arranged in the housing 3, the intake side vane rotor 4 is fixed to the intake side camshaft 2, the exhaust side vane rotor 5 is connected so as to rotate together with an exhaust camshaft 20, and a phase switching means is provided for rotating the vane rotors by being switched to either of the initial position for fixing both the intake side- exhaust side vane rotors 4 and 5 to the rotor housing 3, an intake-exhaust simultaneous ignition timing log position for moving both the intake side-exhaust side vane rotors 4 and 5 to the ignition timing log side from the initial position, and an intake ignition timing advance position for rotating the intake side vane rotor 4 to the ignition timing advance side from the initial position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a DOHC type 4
The present invention relates to a variable valve timing mechanism of a valve train in which a rotation phase of a camshaft is changed in order to change a valve opening / closing timing in a cycle engine, and in particular, an intake camshaft and an exhaust cam by one mechanism installed on the intake camshaft. The present invention relates to a variable valve timing mechanism that changes both rotational phases of a shaft.

[0002]

2. Description of the Related Art In a four-stroke engine having a DOHC type valve system, an intake camshaft or an exhaust cam with respect to a driving rotation of a crankshaft is used as means for changing the opening / closing timing of an intake valve or an exhaust valve in accordance with the operating state of the engine. 2. Description of the Related Art A variable valve timing mechanism (VVT) of a so-called valve train in which the rotation phase of a shaft is changed by switching control of a hydraulic pressure by a solenoid is conventionally known.

[0003] Then, by using such a variable valve timing mechanism of the valve train, the intake and exhaust valves for the purpose of improving fuel efficiency are provided.
When performing both the simultaneous exhaust retard control and the intake advance control for improving the torque, for example, the crankshaft and the exhaust camshaft are linked in the primary chain, and the exhaust camshaft and the intake camshaft are linked in the secondary chain. And a two-stage chain layout driven by an exhaust camshaft. In this method, the simultaneous valve retardation of intake and exhaust is controlled by the variable valve timing mechanism of the valve device on the exhaust side, and the advance angle of intake is controlled by the variable valve timing mechanism of the valve device on the intake side. I have. The crankshaft and intake camshaft are linked in the primary chain, and the intake camshaft and exhaust camshaft are linked in the secondary chain. Some control both the angle control.

Further, there is a single-stage chain layout in which a crankshaft, an exhaust camshaft, and an intake camshaft are linked by the same timing chain.

[0005]

In the case where both the simultaneous intake / exhaust retard control and the intake advance control are performed by using the variable valve timing mechanism of the valve train, the conventional method as described above is used. In either case, it is necessary to install variable valve timing mechanisms of the valve operating devices on the intake camshaft side and the exhaust camshaft side, respectively. Control is required.

On the other hand, for example, as a two-stage chain layout for driving the intake camshaft, a variable valve timing mechanism of a valve train is installed only on the intake camshaft side, and the variable valve of this one valve train is mounted. It has been considered that both the intake advance control and the intake / exhaust simultaneous retard control are performed by the timing mechanism, so that there is no need to install a variable valve timing mechanism of the valve train on the exhaust camshaft. The engine can be reduced in weight and size, and the exhaust valve does not require a variable valve timing mechanism of a valve train, a solenoid and an oil passage associated therewith, so that costs can be reduced.

However, in order to perform both the simultaneous intake / exhaust retard control and the intake advance control by the variable valve timing mechanism of one valve operating device, the variable valve timing mechanism of the valve operating device is a component. For each of the intake control and exhaust control vane rotors, the exhaust control vane rotor is operated in the rotation range between the initial position and the retarded position by hydraulic pressure switching control by one solenoid, and the intake control vane rotor is moved in the rotation range. It is necessary to operate the motor in the rotation range between the advanced position and the retarded position with the intermediate portion as the initial position.

However, in such a case, the initial position of the intake control vane rotor is located in the middle of the rotation range of the vane rotor, and the simultaneous intake / exhaust retard control and intake advance control are not performed. During normal engine operation, it is practically impossible to stably hold the intake control vane rotor at the initial position in the middle of the rotation range only by control using the hydraulic pressure from the solenoid.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems. Specifically, one variable valve timing mechanism performs both intake and exhaust simultaneous retard control and intake advance control. It is an object of the present invention to provide a variable valve timing mechanism of a valve train in which a vane rotor for intake control can be reliably held at an initial position.

[0010]

According to a first aspect of the present invention, there is provided an intake valve, comprising: an intake camshaft rotatably driven by a crankshaft; and an exhaust camshaft rotatable by the intake camshaft. The rotation of the crankshaft is transmitted to a variable valve timing mechanism of a valve gear that opens and closes an exhaust valve and variably controls the opening and closing timing of each of the intake and exhaust valves according to the operating state of the engine. A rotor housing is mounted on the intake camshaft so as to be relatively rotatable, and an intake vane rotor and an exhaust vane rotor are disposed in the rotor housing so as to be relatively rotatable and coaxial, and the intake vane rotor is connected to the intake cam. The exhaust-side vane rotor is fixed to a shaft, and the exhaust-side vane rotor is connected to the exhaust camshaft so as to rotate together. An intake / exhaust simultaneous retard position in which both the intake side and exhaust side vane rotors are unlocked from the rotor housing and moved to a retard side from the initial position. A phase switching means for releasing the fixing to the rotor housing and switching to any one of the intake advanced position to rotate from the initial position to the advanced side and rotating.

According to a second aspect of the present invention, in the first aspect, the phase switching means rotates the intake side vane rotor from the initial position to the retard side or the advance side by hydraulic pressure, and causes the exhaust side vane rotor to rotate. A hydraulic drive mechanism for rotating from the initial position to the retard side, a lock pin member for fixing the intake side and exhaust side vane rotors or fixing both vane rotors to the rotor housing, and a lock pin member. In the initial position, both the intake-side and exhaust-side vane rotors are moved so as to be fixed to the rotor housing. At the simultaneous intake / exhaust delay position, the intake-side and exhaust-side vane rotors are moved so as to be fixed. And a lock pin switching mechanism for releasing the suction side vane rotor from being fixed to the rotor housing.

[0012]

According to the variable valve timing mechanism according to the first aspect of the present invention, the rotor housing driven by the crankshaft is mounted on the intake camshaft and connected to the intake camshaft inside the rotor housing. The intake side vane rotor and the exhaust side vane rotor connected to the exhaust side camshaft are housed, and both the intake side and exhaust side vane rotors can be rotated from the initial position to the retard side, and only the intake side vane rotor is in the initial position. , The rotation phase of both the intake and exhaust camshafts can be changed with a single variable valve timing mechanism. An advance angle can be realized.
As a result, the engine can be made lighter and more compact than when a variable valve timing mechanism is installed on both camshafts, and the associated solenoids and oil passages are not required, thereby reducing costs. be able to.

In the present invention, both the intake side and exhaust side vane rotors are fixed to the rotor housing at the initial position.
When turning to the simultaneous intake and exhaust retarding position, the fixing of both vane rotors to the rotor housing is released, and when turning to the intake advanced position, the fixing of the suction side vane rotor to the rotor housing is released. Also, the intake side vane rotor can be reliably held at the initial position which is an intermediate position, and the phase can be switched stably with respect to the simultaneous retarding of the intake and exhaust valves and the advance of the intake valve.

According to the second aspect of the present invention, a lock pin member for fixing both vane rotors or fixing both vane rotors to the rotor housing is provided, and the lock pin member is moved to the initial position by a hydraulic lock pin switching mechanism. When in the position, both the intake-side and exhaust-side vane rotors are moved to engage with the rotor housing, and when in the intake / exhaust simultaneous retard position, the fixing of both the vane rotors to the rotor housing is released, and the intake advance When the engine is in the position, the fixing of both vane rotors is released, so when the intake side vane rotor and the exhaust side vane rotor are both in the initial position during normal engine operation, the lock pin member connects both vane rotors to the rotor housing. By engaging and fixing, the intake side vane in the middle part of the rotation range Chromatography data is securely fixed and held to the initial position by the locking pin member.

When the intake advancing control is started from an initial state in which both the intake-side vane rotor and the exhaust-side vane rotor are at the initial positions, the fixing of the two vane rotors is released by the hydraulic pressure switching mechanism, and the vane rotors become free. Only the suction side vane rotor rotates from the initial position to the advanced position.

When the simultaneous intake and exhaust retard control is started from the initial state, the fixing of both vane rotors to the rotor housing by the lock pin members is released,
And it rotates from the initial position to the retarded position while being integrally connected by the lock pin member.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 7 are views for explaining a variable valve timing mechanism of a valve gear according to an embodiment of the present invention. FIG. 1 shows main components of the variable valve timing mechanism of the valve gear. FIG. 2 is an exploded perspective view, FIG. 2 is a cross-sectional view of the variable valve timing mechanism as viewed in a plane in the cylinder axial direction, FIG. 3 is a cross-sectional view of the first vane rotor of the variable valve timing mechanism (a cross-sectional view taken along line III-III in FIG. 2), and FIG. FIG. 5 is a sectional view of the second vane rotor (a sectional view taken along line IV-IV in FIG. 2), FIG. 5 is a view showing the retarding and advancing operations of each vane rotor, and FIG. 6 is a V-type 4 provided with a variable valve timing mechanism. FIG. 7 is a schematic front view of a cycle engine, FIG.
It is a figure showing an advance operation.

The variable valve timing mechanism of the valve train according to the present embodiment is provided with a valve system for an intake camshaft of a four-stroke engine of a DOHC type. By controlling the switching of the intake-side and exhaust-side vane rotors between an initial position, an intake / exhaust simultaneous retard position, and an intake advance position through the intake camshaft and the exhaust camshaft relative to the angular position of the crankshaft. The rotational phase (relative angular position) of the camshaft is changed.

The engine 11 in which the variable valve timing mechanism of the present embodiment is installed is a four-cycle V-type eight-cylinder engine, which connects a common crankcase 13 to a lower mating surface of a cylinder block 12 and Left and right cylinder portions 12a, which are integrally formed to form a bank,
This is a schematic structure in which a cylinder head 14 is connected to the upper mating surface of the cylinder head 12a. Two intake valves 14a are provided for each cylinder inside the V bank of each cylinder head 14, and two exhaust valves 14b are provided for each cylinder outside the V bank so as to open and close intake and exhaust ports, respectively. Have been.

The cylinder head 14 is provided with an intake camshaft 2 and an exhaust camshaft 20 for opening and closing the intake valve 14a and the exhaust valve 14b, respectively, in parallel with the crankshaft 15. The drive rotation of the crankshaft 15 is transmitted from the primary chain 16 to the intake camshaft 2 via the variable valve timing mechanism, and the rotation of the intake camshaft 2 is transmitted from the variable valve timing mechanism via the secondary chain 17 to the exhaust camshaft. 20. This is based on the so-called two-stage chain layout driven by the intake camshaft, and the exhaust camshaft 20 is not provided with a variable valve timing mechanism.

The variable valve timing mechanism 1 includes a rotor housing front end member 3 constituting the rotor housing 3.
1, a rotor housing main body 32, a rotor housing rear end member 33, an intake side vane rotor 4 for intake control, an exhaust side vane rotor 5 for exhaust control, a cam shaft linking member 6 linked to the exhaust cam shaft 20, A lock pin member 7 for holding the side vane rotor 4 at the initial position, a plate-wound spring 8 (including spring locking pins 81 and 82) interposed between the rotor housing 3 and the intake camshaft 2; Each of the connecting bolts 9 and 10 is a component.

In the variable valve timing mechanism 1, intake air is supplied to a front end portion of an intake camshaft 2 in which oil passages 21 and 22 to which hydraulic pressure is supplied from a solenoid valve (not shown) constituting a hydraulic pressure switching mechanism are formed. The side vane rotor 4 is integrally fixed by a connecting bolt 9, and a camshaft linking member 6 having spline teeth 6 a on a front outer peripheral surface is provided on the rear side of the intake side vane rotor 4 relative to the intake camshaft 2. A secondary sprocket 61 for winding the secondary chain 17 for linking with the exhaust camshaft 20 is integrally formed on the outer peripheral surface of the rear end of the camshaft linking member 6 so as to be rotatable. ing.

On the rear side of the intake-side vane rotor 4 and outside the front part of the camshaft linking member 6, an exhaust-side vane rotor 5 having spline teeth 5a on the inner peripheral surface is provided with spline teeth 6a of the camshaft linking member 6. The intake-side vane rotor 4 and the exhaust-side vane rotor 5 are arranged back and forth in the axial direction so as to be in sliding contact with each other. In FIG. 2, the upper part of the drawing is the front of the engine, and the lower part of the drawing is the rear of the engine.

On the other hand, a rotor housing 3 for accommodating the intake side vane rotor 4 and the exhaust side vane rotor 5 is provided.
Is formed by integrally connecting the front end member 31, the rotor housing main body 32, and the rear end member 33 with the connection bolts 10, and the rear end member 33 of the rotor housing 3 is formed.
A primary sprocket 34 for winding the primary chain 16 for transmitting the rotational drive of the crankshaft 15 is formed on the outer periphery of the primary sprocket 34.

The intake-side vane rotor 4 and the exhaust-side vane rotor 5 are housed in the rotor housing 3 so as to be relatively rotatable within a predetermined rotation range, and the intake cam to which the intake-side vane rotor 4 is fixed. For axis 2,
The rotor housing 3 and the camshaft linking member 6 are disposed coaxially and relatively rotatable. The rear portion of the camshaft linking member 6 projects rearward from the rotor housing 3, and the secondary sprocket 61 formed on the projection is located rearward of the primary sprocket 34 formed on the rear end member 33 of the rotor housing 3. It is located in.

A plate winding is provided between the rotor housing 3 provided with the primary sprocket 34 and the intake side vane rotor 4 fixed to the intake cam shaft 2 on the front side of the rotor housing 3 (in front of the front end member 31). A spring 8 is interposed, and a spring locking pin 81 for fixing one end of the leaf-wound spring 8 is fixed to the rotor housing front end member 31,
Spring locking pin 82 for fixing the other end of leaf spring 8
Are fixed to the intake-side vane rotor 4 through a long hole 31 a in the circumferential direction formed in the front end member 31 of the rotor housing.

Since the plate-wound spring 8 is interposed between the rotor housing 3 and the intake-side vane rotor 4 in this manner, a rotor integrally provided with a primary sprocket 34 to which the rotational drive of the crankshaft 15 is transmitted. Housing 3
When the rotation phase is changed from the initial state to the retard side or the advance side between the intake camshaft 2 to which the intake-side vane rotor 4 is fixed, an attempt is made to return the rotational phase between the two to the initial state. The urging force is applied by the restoring spring force of the leaf spring 8.

Each vane rotor 4, 5 housed in the rotor housing 3 of the variable valve timing mechanism 1
The initial position of the intake-side vane rotor 4 is set in the middle of the rotation range, as shown in FIG. 3, and the rotation of the intake-side vane rotor 4 in both directions from the state to the retard position and the advance position is performed. Is acceptable. On the other hand, as shown in FIG. 4, the exhaust side vane rotor 5 has an initial position set at one end of the rotation range, and is allowed to rotate only in one direction from this state to the retard position. 2 to 4 show a state in which each of the vane rotors 4 and 5 is at an initial position.

The rotation range of each of the vane rotors 4 and 5 will be described more specifically. The inner peripheral surface of the rotor housing body 32 of the rotor housing 3 accommodating each of the vane rotors 4 and 5 is shown in FIGS. As shown in FIG. 2, a plurality (four in the present embodiment) of partition walls 32a and 32b protruding inward are formed at equal intervals in the circumferential direction. Partition portions 32a, 3 slidingly contacting the outer peripheral surfaces of rotor portions 41, 51 which are the rotation center portions of vane rotors 4, 5
The partition wall 2b is formed such that the partition wall portion 32a at the front and the rear partition wall portion 32b of the rotor housing main body 32 from the center in the axial direction have different circumferential lengths (wall thicknesses).

As a result, as shown in FIG. 3, the circumferential length of the partition wall portion 32a itself is reduced before the axial center of the rotor housing body 32 (the partition wall portion 3a).
2a) so that the partition wall portions 3 which are circumferentially adjacent to each other
The distance (length of the oil chamber) between the 2a is increased, and the movable distance of the vane portion (the vane portion of the intake-side vane rotor 4) 42 reciprocating in the oil chamber (between the adjacent partition portions 32a, 32a) is increased. By doing so, a large rotation range of the intake-side vane rotor 4 is allowed.

Further, behind the center of the rotor housing body 32 in the axial direction, as shown in FIG.
2b itself is increased in the circumferential direction (thickness of the partition portion 32b is increased), the interval between the partition portions 32b adjacent in the circumferential direction (the length of the oil chamber) is reduced, and the oil chamber ( By reducing the movable distance of the vane portion (the vane portion of the exhaust-side vane rotor 5) 52 that reciprocates between the adjacent partition portions 32b, 32b, the rotation range of the exhaust-side vane rotor 5 is allowed to be small. .

As described above, in each of the oil chambers formed by partitioning between the rotor housing 3 and each of the vane rotors 4 and 5 by the partition portions 32a and 32b, the vane portions 42 and 52 of the vane rotors 4 and 5 are provided. One side becomes a retard side oil chamber R (oil chamber for operating in the advance direction), and the other side becomes an advance side oil chamber A (oil chamber for operating in the retard direction). The rotor portion 41 of the intake-side vane rotor 4 has an oil passage 43 for communicating the oil passage 21 of the intake camshaft 2 with the retard-side oil chamber R, an oil passage 22 of the intake camshaft 2 and an advance-side oil. An oil passage 44 for communicating the chamber A is formed.

The vane portions 42, 52 of the respective vane rotors 4, 5 are provided with stopper pins 5 at the retarded end portions of the pair of vane portions 42, 52 and on the exhaust-side vane rotor 5 side.
5 is formed, and a groove-shaped stopper pin receiving portion 45 is formed on the side of the intake side vane rotor 4. At the time of simultaneous intake and exhaust retard control, the stopper pin 55 and the stopper pin receiving portion 45 are brought into contact to operate the intake-side vane rotor 4 and the exhaust-side vane rotor 5 in an interlocked manner. When the stopper pin receiving portion 45 is separated from the pin 55, only the intake side vane rotor 4 can be operated.

Further, each of the vane rotors 4 and 5 and the rotor housing 3 have a pair of opposing lock pins 7a and 7b.
The expandable and contractible lock pin member 7 including the spring 7c interposed therebetween holds the intake-side vane rotor 4 at the initial position in the middle of the rotation range when the vane rotors 4 and 5 are in the initial position. In order to achieve this, it is provided so as to penetrate the exhaust-side vane rotor 5 and engage with each of the intake-side vane rotor 4 and the rotor housing 3 (the rear end member 33).

Further, the intake side vane rotor 4 and the rotor housing 3 (the rear end member 33) which engage with the lock pin member 7.
As shown in FIGS. 5A to 5C, engagement recesses 48 formed in the intake-side vane rotor 4 are respectively provided.
, An oil passage 46 for communicating with the retard side oil chamber R is formed, and the rotor housing 3 (the rear end member 3
With respect to the engagement recess 38 formed in 3), the advance side oil chamber A
Oil passages 37 and 47 for communicating with the oil passage are formed.

According to the variable valve timing mechanism 1 of the present embodiment having the above configuration, as shown in FIG. 5B, the intake side vane rotor 4 and the exhaust side vane rotor 5
Are in the initial positions, the lock pin members 7
Are engaged with each of the intake side vane rotor 4 and the rotor housing 3 through the exhaust side vane rotor 5, so that the intake side vane rotor 4
Can be securely fixed and held at the initial position by the lock pin member 7.

When the intake advance control is started, the vane rotors 4 and 5 are moved from an initial state where both are at the initial positions.
As shown in FIG. 5A, first, the hydraulic oil is introduced into the retard-side oil chamber R and the hydraulic oil is discharged from the retard-side oil chamber A. As shown in FIG. Hydraulic pressure acts on the engaging recess 48 of the intake-side vane rotor 4 through the passage, the lock pin 7a is retracted, and the engagement between the lock pin member 7 and the intake-side vane rotor 4 is released. Only the side vane rotor 4 moves to the advanced position in the rotor housing 3 by the hydraulic pressure from the retard side oil chamber R.

When the simultaneous intake / exhaust retard control is started, hydraulic oil is introduced into the advance-side oil chamber A from the initial state in which the vane rotors 4 and 5 are both at the initial position, and the retard-side oil chamber R
As shown in FIG. 5 (C), first, the engagement recess 3 of the rotor housing 3 (rear end member 33) passes through the oil passages 47 and 37 from the advance side oil chamber A, as shown in FIG.
8, the lock pin 7b is retracted to disengage the lock pin member 7 from the rotor housing 3 (the rear end member 33), and thereafter, the intake-side vane rotor connected by the lock pin member 7. 4 and the exhaust side vane rotor 5 are both rotated by the hydraulic pressure from the advance side oil chamber A.
Move to the retard position within.

FIG. 7 shows the timing operation of the intake and exhaust valves. In the figure, (D) shows a single-stage chain layout in which the crankshaft and the intake and exhaust camshafts are connected by one timing chain, and (E) shows that the crankshaft and the exhaust camshaft are connected by the primary chain. The exhaust-side two-stage chain layout in which an exhaust camshaft and an intake camshaft are connected by a secondary chain is shown. (F) shows a crankshaft and an intake camshaft connected by a primary chain, and an intake camshaft by a secondary chain. 2 shows a layout of a two-stage chain on the intake side in which an exhaust camshaft and an exhaust camshaft are connected. In addition,
(D) and (E) show conventional examples in which a variable valve timing mechanism is arranged on each of the intake and exhaust camshafts.
(F) shows this embodiment in which the variable valve timing mechanism is arranged only on the intake camshaft. (A) shows intake air
Simultaneous exhaust delay operation, (b) initial position, (c)
Indicates an intake advancing operation.

When the engine operating range is, for example, in the low-load low-rotation range or the high-load high-rotation range, the rotational phases of both the exhaust camshaft and the intake camshaft are held at the initial position at the phase angle of 0 ° (initial). b). When the engine is in the medium load / medium rotation range, the rotation phases of the exhaust camshaft and the intake camshaft are retarded by α in order to improve fuel efficiency (simultaneous retard a). When the engine is in the high-load, low-speed range, the rotational phase of the intake camshaft is advanced by β in order to improve the torque (advance c).

On the other hand, in the variable valve timing mechanism 1 of this embodiment, as described above, the intake side vane rotor 4 and the exhaust side vane rotor 5
Are operated in conjunction with each other, and only the intake-side vane rotor 4 is operated during intake advance control.
5 and the stopper pin 55 and the stopper pin receiving portion 4
5 are formed.

However, only the stopper pin 55 and the stopper pin receiving portion 45 have different loads, for example, from the intake camshaft side and the exhaust camshaft side during the simultaneous intake and exhaust delay control. In such a case, when the control starts and the vane rotors 4 and 5 move from the initial position, the exhaust-side vane rotor 5 starts to operate earlier than the intake-side vane rotor 4, or the control ends. When each of the vane rotors 4 and 5 returns to the initial position, the intake-side vane rotor 4 is
If the operation is started earlier in advance of the above, there is a possibility that a difference occurs in the control timing between the intake side and the exhaust side.

On the other hand, in the present embodiment, during the simultaneous intake and exhaust retard control, the intake-side vane rotor 4 and the exhaust-side vane rotor 5 are completely connected by the lock pin member 7 and operate in either direction. However, since there is no deviation in operation between the intake camshaft and the exhaust camshaft, for example, even when the magnitude of the load from the intake camshaft side is different from that of the exhaust camshaft side, there is no difference in operation. There is no deviation in the control timing, and the retard control can be performed at the same time. In particular, at the time of retard control for changing the rotation phase in the direction opposite to the engine rotation direction, the two vane rotors 4 and 5 can cooperate to reliably perform retard control.

In the above embodiment, the case where the variable valve timing mechanism is arranged on the intake camshaft has been described.
For a variable valve timing mechanism outside the scope of the present invention, the mechanism may be located on the exhaust camshaft. In this case, the intake camshaft can rotate only to the advance side, and the exhaust side can rotate to both the retard side and the advance side.

As shown in FIG. 8, when a single-stage chain layout in which the crankshaft, the intake camshaft 2, and the exhaust camshaft 20 are connected by one timing chain 70 via cams plots 71, 72, A variable valve timing mechanism 75 similar to the above-described embodiment is attached to the camshaft 2.
Can also be attached. In this case, the variable valve timing mechanism 75 in which the first and second vane rotors 4 and 5 are accommodated in the rotor housing 3 is disposed on the intake camshaft 2 side, and the variable valve timing mechanism in which one vane rotor 77 is accommodated in the housing 76. 78 is arranged on the exhaust camshaft 20 side. The intake camshaft 2 can rotate relatively to both the retard side and the advance side from the illustrated initial position, and the exhaust camshaft 20 can rotate only to the retard side from the initial position.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of main components of a variable valve timing mechanism of a valve train according to an embodiment of the present invention.

FIG. 2 is a sectional view of the variable valve timing mechanism.

FIG. 3 is a cross-sectional view (a cross-sectional view taken along line III-III in FIG. 2) of a first vane rotor of the variable valve timing mechanism.

FIG. 4 is a cross-sectional view (a cross-sectional view taken along line IV-IV in FIG. 2) of a second vane rotor of the variable valve timing mechanism.

FIG. 5 is a diagram showing retarding and advancing operations of the vane rotors.

FIG. 6 is provided with the variable valve timing mechanism.
1 is a schematic front view of a V-type four-cycle engine.

FIG. 7 is a diagram showing retarding and advancing operations of the variable valve timing mechanism.

FIG. 8 is a cross-sectional view showing an example in which a variable valve timing mechanism is arranged in a single-stage chain layout.

[Explanation of symbols]

 1,75 Variable valve timing mechanism 2 Intake camshaft 3 Rotor housing 4 Intake side vane rotor 5 Exhaust side vane rotor 7 Lock pin member 14a Intake valve 14b Exhaust valve 15 Crankshaft 20 Exhaust camshaft

Claims (2)

[Claims] An intake valve and an exhaust valve are opened and closed via an intake camshaft rotationally driven by a crankshaft and an exhaust camshaft rotationally driven by the intake camshaft. In the variable valve timing mechanism of the valve train, wherein the opening / closing timing of each valve is variably controlled according to the operation state of the engine, a rotor housing to which rotation of the crankshaft is transmitted is rotated relative to the intake camshaft. The intake side and exhaust side vane rotors are disposed so as to be relatively rotatable and coaxial within the rotor housing, the intake side vane rotor is fixed to the intake side cam shaft, and the exhaust side vane rotor is exhausted. An initial position in which both the intake-side and exhaust-side vane rotors are connected to the camshaft so as to be fixed to the rotor housing; The simultaneous intake / exhaust delay position where both the exhaust-side vane rotors are fixed to the rotor housing and moved to the retard side from the initial position, and the intake-side vane rotor is fixed to the rotor housing and released. A variable valve timing mechanism for a valve operating device, comprising: a phase switching means for switching to and rotating from an initial position to an intake advanced position for rotating to an advanced side. 2. The phase switching means according to claim 1, wherein the phase switching means rotates the intake-side vane rotor from the initial position to a retard side or an advance side by hydraulic pressure, and retards the exhaust-side vane rotor from the initial position. A hydraulic drive mechanism for rotating to the corner side, a lock pin member for fixing the intake side and exhaust side vane rotors or fixing both the vane rotors to the rotor housing, and the lock pin member in the initial position. Both the intake side and exhaust side vane rotors are moved to be fixed to the rotor housing, the intake side and exhaust side vane rotors are moved so as to be fixed at the simultaneous intake / exhaust retard position, and the intake side vane rotor is moved at the intake advance position. And a lock pin switching mechanism for releasing the fixing to the housing. Mechanism.