JP4336057B2 - Variable valve timing mechanism of valve gear - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a variable valve timing mechanism of a valve operating system in which the rotational phase of a camshaft is changed in order to change the opening / closing timing of a valve in a DOHC type four-cycle engine. The present invention relates to a variable valve timing mechanism in which the rotational phases of both an intake cam shaft and an exhaust cam shaft are changed by the mechanism.
[0002]
[Prior art]
In a 4-cycle engine with a DOHC valve system, the rotation phase of the intake camshaft and exhaust camshaft relative to the crankshaft drive rotation is used as a means to change the opening and closing timing of the intake valve and exhaust valve according to the operating state of the engine. A so-called variable valve timing mechanism (VVT) of a valve operating apparatus that is changed by hydraulic pressure switching control using a solenoid is conventionally known.
[0003]
And, using such a variable valve timing mechanism of a valve operating system, when performing both intake and exhaust simultaneous retard control for improving fuel efficiency and intake advance control for improving torque For example, there is an exhaust camshaft driven two-stage chain layout in which a crankshaft and an exhaust camshaft are linked in a primary chain and an exhaust camshaft and an intake camshaft are linked in a secondary chain. This is a method in which the intake and exhaust simultaneous retarding angle is controlled by the variable valve timing mechanism of the exhaust side valve device, and the intake advance angle is controlled by the variable valve timing mechanism of the intake side valve device. Yes. In addition, a two-stage chain layout of intake camshaft drive, in which the crankshaft and intake camshaft are linked in the primary chain and the intake camshaft and exhaust camshaft are linked in the secondary chain, and simultaneous intake and exhaust retard control and intake advance Some have both angle controls.
[0004]
Further, there is a one-stage chain layout in which a crankshaft, an exhaust camshaft, and an intake camshaft are linked by the same timing chain.
[0005]
[Problems to be solved by the invention]
By the way, when both the intake / exhaust simultaneous retardation control and the intake advance control are performed by using the variable valve timing mechanism of the valve operating device, the intake cam is in either case according to the conventional method as described above. It is necessary to install variable valve timing mechanisms of the valve operating devices on the shaft side and the exhaust cam shaft side, respectively, and it is necessary to control the variable valve timing mechanisms of the respective valve operating devices by individual solenoids.
[0006]
In contrast, for example, as a two-stage chain layout for intake camshaft drive, a variable valve timing mechanism of a valve operating device is installed only on the intake camshaft side, and the variable valve timing mechanism of this single valve operating device is used. It has been studied to perform both intake advance angle control and intake / exhaust simultaneous retard angle control, so that it is not necessary to install a variable valve timing mechanism of the valve gear on the exhaust camshaft. The weight can be reduced and the size can be reduced, and the variable valve timing mechanism of the valve operating device and the related solenoid and oil passage are not required on the exhaust side, so that the cost can be reduced.
[0007]
However, in order to perform both the intake / exhaust simultaneous retard angle control and the intake advance angle control by the variable valve timing mechanism of one valve operating device, for the intake control which is a component of the variable valve timing mechanism of the valve operating device. For each vane rotor for exhaust control and exhaust control, the exhaust control vane rotor is operated in the rotation range of the initial position and the retarded angle position by hydraulic switching control by one solenoid, and the intake control vane rotor is operated in the middle of the rotation range. It is necessary to operate in the rotation range of the advance angle position and the retard angle position with the initial position as the initial position.
[0008]
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 a normal engine that does not perform simultaneous intake / exhaust retard control or intake advance control During 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 the control by the hydraulic pressure from the solenoid.
[0009]
An object of the present invention is to solve the above-described problems. Specifically, both intake / exhaust simultaneous retard control and intake advance control can be performed by one variable valve timing mechanism. Another object of the present invention is to provide a variable valve timing mechanism for a valve operating apparatus that can reliably hold an intake control vane rotor at an initial position.
[0010]
[Means for Solving the Problems]
According to the first aspect of the present invention, the intake valve and the exhaust valve are opened and closed via the intake side camshaft that is rotationally driven by the crankshaft and the exhaust side camshaft that is rotationally driven by the intake side camshaft. , In the variable valve timing mechanism of the valve operating system, the opening / closing timing of each exhaust valve is variably controlled according to the operating state of the engine
A rotor housing to which rotation of the crankshaft is transmitted is mounted on the intake side camshaft so as to be relatively rotatable, and intake side and exhaust side vane rotors are installed in the rotor housing. Against the rotor housing Relative rotation and coaxial None In addition, the same hydraulic pressure is applied The intake side vane rotor is fixed to the intake side camshaft, the exhaust side vane rotor is connected to the exhaust camshaft so as to rotate together, and both the intake side and exhaust side vane rotor are fixed to the rotor housing. And position it at the initial position, Release both the intake and exhaust vane rotors from the rotor housing By The intake / exhaust simultaneous retarded position to move to the retarded side from the initial position and the intake vane rotor fixed to the rotor housing are released. By It is characterized by comprising phase switching means for switching to any one of the intake advance angle positions rotated to the advance angle side from the initial position.
[0011]
According to a second aspect of the present invention, in the first aspect, the phase switching unit rotates the intake side vane rotor from the initial position to the retard side or the advanced side by hydraulic pressure, and causes the exhaust side vane rotor to move to the initial position. A hydraulic drive mechanism that pivots to a retard angle side, a lock pin member that fixes the intake side and exhaust side vane rotors together, or that fixes the vane rotors to a rotor housing, and the lock pin member at the initial position. Then, both the intake side and exhaust side vane rotors are moved so as to be fixed to the rotor housing, the intake side and exhaust side vane rotors are moved so as to be fixed at the intake / exhaust simultaneous retard position, and the intake side vane rotor is fixed at the intake advance position. And a lock pin switching mechanism for releasing the fixing to the rotor housing.
[0012]
[Effects of the invention]
According to the variable valve timing mechanism of the first aspect of the invention, an intake side vane rotor connected to the intake side camshaft in the rotor housing, wherein the rotor housing driven by the crankshaft is mounted on the intake side camshaft; The exhaust side vane rotor connected to the exhaust side camshaft is 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 can be rotated from the initial position to the advance side. Because it is movable, the rotational phase of both the intake and exhaust camshafts can be changed with a single variable valve timing mechanism, realizing simultaneous retarding of the intake and exhaust valves and advancement of the intake valves Can do. As a result, the engine can be made lighter and more compact than when variable valve timing mechanisms are installed on both camshafts, and the associated solenoids and oil passages are not required, thus reducing costs. be able to.
[0013]
In the present invention, both the intake side and exhaust side vane rotors are fixed to the rotor housing at the initial position, and when rotating to the intake / exhaust simultaneous retarding position, the fixing of both vane rotors to the rotor housing is released and the intake advance angle is released. Since the intake-side vane rotor is released from being fixed to the rotor housing when it is rotated to the position, the intake-side vane rotor can be securely held at the initial position, which is an intermediate position, and the intake and exhaust valves can be delayed at the same time. Stable phase switching can also be performed for the angle and the advance angle of the intake valve.
[0014]
According to the second aspect of the present invention, there is provided a lock pin member for fixing both the vane rotors to each other or for fixing both the vane rotors to the rotor housing, and when the lock pin member is in the initial position by the hydraulic lock pin switching mechanism. Both the intake-side and exhaust-side vane rotors are moved so as to engage with the rotor housing, and when the intake-exhaust simultaneous retarded position is released, the fixing of both of the vane rotors to the rotor housing is released. Since both vane rotors are unlocked, 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 engages both vane rotors with the rotor housing. The vane rotor on the intake side in the middle of the rotation range. It is securely fixed and held to the initial position by Kupyn member.
[0015]
When the intake angle advancement control is started from the initial state where both the intake side vane rotor and the exhaust side vane rotor are in the initial position, the fixing of both the vane rotors is released by the hydraulic pressure switching mechanism and the intake side becomes free. Only the vane rotor rotates from the initial position to the advanced position.
[0016]
When the intake / exhaust simultaneous retarding control is started from the initial state, the lock pin member is not fixed to the rotor housing of both vane rotors, and the initial position is integrally connected by the lock pin member. To the retarded position.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0018]
1 to 7 are views for explaining a variable valve timing mechanism of a valve operating apparatus according to an embodiment of the present invention. FIG. 1 is an exploded perspective view of main components of the variable valve timing mechanism of the valve operating apparatus. 2 is a cross-sectional view of the variable valve timing mechanism as viewed in the cylinder axial plane, FIG. 3 is a cross-sectional view of the first vane rotor of the variable valve timing mechanism (cross-sectional view taken along the line III-III in FIG. 2), and FIG. 5 is a cross-sectional view of the vane rotor (cross-sectional view taken along the line IV-IV in FIG. 2), FIG. 5 is a view showing the retarding and advancing operation of each vane rotor, and FIG. FIG. 7 is a schematic front view, and FIG. 7 is a diagram showing a retarding and advancing operation by the variable valve timing mechanism.
[0019]
The variable valve timing mechanism of the valve operating apparatus according to the present embodiment is installed on the intake camshaft of a four-cycle engine whose valve system is of the DOHC type, and a hydraulic pressure switching mechanism (not shown) is provided by phase switching means. By switching the intake side and exhaust side vane rotors, which will be described later, between the initial position, the intake / exhaust simultaneous retarded angle position, and the intake advanced angle position, the intake camshaft and exhaust camshaft position relative to the angular position of the crankshaft is controlled. The rotational phase (relative angular position) is changed.
[0020]
The engine 11 in which the variable valve timing mechanism of this embodiment is installed is a 4-cycle V-type 8-cylinder engine, which connects a common crankcase 13 to the lower joint surface of the cylinder block 12 and forms a V bank. In this way, the cylinder head 14 is connected to the upper joint surfaces of the left and right cylinder portions 12a, 12a that are integrally formed. Two intake valves 14a for each cylinder are arranged inside the V bank of each cylinder head 14 and two exhaust valves 14b are arranged outside the V bank so that the intake and exhaust ports can be opened and closed. Has been.
[0021]
The cylinder head 14 is provided with an intake camshaft 2 and an exhaust camshaft 20 parallel to the crankshaft 15 for opening and closing the intake valve 14a and the exhaust valve 14b, respectively. 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 discharged from the variable valve timing mechanism via the secondary chain 17 to the exhaust camshaft. 20 is transmitted. This is due to the so-called intake camshaft driven two-stage chain layout, and the exhaust camshaft 20 is not provided with a variable valve timing mechanism.
[0022]
The variable valve timing mechanism 1 includes a rotor housing front end member 31, a rotor housing body 32, a rotor housing rear end member 33, an intake side vane rotor 4 for intake control, and an exhaust side vane rotor for exhaust control. 5, a camshaft linking member 6 linked to the exhaust camshaft 20, a lock pin member 7 for holding the intake side vane rotor 4 in the initial position, and the rotor housing 3 and the intake camshaft 2 are interposed. The plate spring 8 (including the spring locking pins 81 and 82) and the connecting bolts 9 and 10 are used as components.
[0023]
In the variable valve timing mechanism 1, the intake side vane rotor 4 is opposed to the front end portion of the intake camshaft 2 in which oil passages 21, 22 to which hydraulic pressure is supplied from a solenoid valve (not shown) constituting a hydraulic pressure switching mechanism is formed. Is integrally fixed by a connecting bolt 9, and a cam shaft linking member 6 having spline teeth 6 a on the outer peripheral surface of the front portion is rotatable relative to the intake cam shaft 2 on the rear side of the intake side vane rotor 4. 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 portion of the camshaft linking member 6.
[0024]
An exhaust side vane rotor 5 having spline teeth 5 a on the inner peripheral surface is fitted to the spline teeth 6 a of the camshaft linkage member 6 on the rear side of the intake side vane rotor 4 and outside the front portion of the camshaft linkage member 6. Accordingly, 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 side of the drawing is the front of the engine, and the lower side of the drawing is the rear of the engine.
[0025]
On the other hand, the rotor housing 3 for housing the intake side vane rotor 4 and the exhaust side vane rotor 5 is formed by integrally connecting the front end member 31, the rotor housing body 32 and the rear end member 33 with the connecting bolt 10. A primary sprocket 34 for winding the primary chain 16 that transmits the rotational drive of the crankshaft 15 is formed on the outer peripheral portion of the rear end member 33 of the rotor housing 3.
[0026]
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 in a predetermined rotation range, and are attached to the intake camshaft 2 to which the intake-side vane rotor 4 is fixed. On the other hand, the rotor housing 3 and the camshaft linking member 6 are coaxially arranged so as to be relatively rotatable. Further, the rear portion of the camshaft linking member 6 protrudes rearward from the rotor housing 3, and the secondary sprocket 61 formed on the protruding portion is rearward of the primary sprocket 34 formed on the rear end member 33 of the rotor housing 3. Is located.
[0027]
A plate spring 8 is provided between the rotor housing 3 provided with the primary sprocket 34 and the intake side vane rotor 4 fixed to the intake camshaft 2 on the front side of the rotor housing 3 (in front of the front end member 31). A spring locking pin 81 that is interposed and fixes one end side of the plate winding spring 8 is fixed to the rotor housing front end member 31, and a spring locking pin 82 that fixes the other end side of the plate winding spring 8 is provided. The rotor housing front end member 31 is fixed to the intake side vane rotor 4 through a circumferential long hole 31 a formed in the rotor housing front end member 31.
[0028]
In this way, the plate spring 8 is interposed between the rotor housing 3 and the intake side vane rotor 4, so that the primary sprocket 34 to which the rotational drive of the crankshaft 15 is transmitted is integrally provided. When the rotation phase is changed from the initial state to the retard side or the advance side with respect to the intake camshaft 2 to which the intake side vane rotor 4 is fixed, the rotational phase between the two is returned to the initial state. The urging force works by the restoring spring force of the plate winding spring 8.
[0029]
Of the vane rotors 4 and 5 housed in the rotor housing 3 of the variable valve timing mechanism 1, the intake side vane rotor 4 has its initial position set in the middle of the rotation range as shown in FIG. In this state, rotation is allowed in both directions from the retarded position to the advanced position and to the advanced position. On the other hand, as shown in FIG. 4, the exhaust vane rotor 5 has its initial position set at one end of the rotation range, and is allowed to rotate only in one direction from this state to the retarded position. 2 to 4 show a state in which the vane rotors 4 and 5 are in their initial positions.
[0030]
More specifically, the rotation ranges of the vane rotors 4 and 5 will be described in detail. The inner peripheral surface of the rotor housing body 32 of the rotor housing 3 that houses the vane rotors 4 and 5 is shown in FIGS. As described above, a plurality (four in this embodiment) of partition wall portions 32a and 32b protruding inward are formed at equal intervals in the circumferential direction. The partition portions 32a and 32b slidably contacting the outer peripheral surfaces of the rotor portions 41 and 51, which are the rotation center portions of the vane rotors 4 and 5, are the front partition portion 32a and the rear partition portion 32b from the approximate center in the axial direction of the rotor housing body 32. And the circumferential lengths (thicknesses of the partition walls) are different from each other.
[0031]
As a result, as shown in FIG. 3, the circumferential length of the partition wall portion 32a itself is made smaller (the thickness of the partition wall portion 32a is made thinner) in front of the center in the axial direction of the rotor housing body 32. A vane portion that reciprocates in the oil chamber (between adjacent partition wall portions 32a, 32a) (vane portion of the intake-side vane rotor 4) by increasing the interval between the partition wall portions 32a adjacent in the circumferential direction (the length of the oil chamber). By increasing the movable distance of 42, the rotation range of the intake side vane rotor 4 is greatly allowed.
[0032]
Further, as shown in FIG. 4, the circumferential length of the partition wall portion 32 b itself is increased (the thickness of the partition wall portion 32 b is increased) behind the center in the axial direction of the rotor housing body 32, A vane portion (vane portion of the exhaust vane rotor 5) 52 that reciprocates in the oil chamber (between adjacent partition wall portions 32b and 32b) by shortening the interval between the partition wall portions 32b adjacent to each other in the direction (the length of the oil chamber). By reducing the movable distance, the rotation range of the exhaust side vane rotor 5 is allowed to be small.
[0033]
In each of the oil chambers formed by partitioning between the rotor housing 3 and the vane rotors 4 and 5 by the partition portions 32a and 32b as described above, the vane portions 42 and 52 of the vane rotors 4 and 5 are used as boundaries. The one side becomes the retarded side oil chamber R (oil chamber for operating in the advance direction), and the other side becomes the advance side oil chamber A (oil chamber for operating in the retarded direction), and the intake side The rotor portion 41 of the vane rotor 4 includes an oil passage 43 for communicating the oil passage 21 of the intake camshaft 2 and the retard side oil chamber R, an oil passage 22 of the intake camshaft 2 and an advance side oil chamber A. An oil passage 44 for communicating with each other is formed.
[0034]
The vane portions 42 and 52 of the vane rotors 4 and 5 are provided with stopper pins 55 on the exhaust side vane rotor 5 at the retarded side ends of the pair of vane portions 42 and 52, respectively. A groove-like stopper pin receiving portion 45 is formed on the side. At the time of simultaneous intake / exhaust retard control, the intake pin vane rotor 4 and the exhaust side vane rotor 5 are operated in an interlocked manner by bringing the stopper pin 55 and the stopper pin receiving portion 45 into contact with each other. Since the stoper pin receiving portion 45 is separated from the pin 55, only the intake side vane rotor 4 can be operated.
[0035]
Further, each vane rotor 4, 5 and the rotor housing 3 are provided with a telescopic lock pin member 7 composed of a pair of opposed lock pins 7 a, 7 b and a spring 7 c interposed between the vane rotors 4, 5. In the initial position, the intake vane rotor 4 and the rotor housing 3 (rear end member 33) pass through the exhaust vane rotor 5 in order to hold the intake vane rotor 4 at the initial position in the middle of the rotation range. It is provided to engage with each other.
[0036]
Each of the intake side vane rotor 4 and the rotor housing 3 (rear end member 33) engaged with the lock pin member 7 includes an intake side vane rotor 4 as shown in FIGS. 5 (A) to 5 (C). An oil passage 46 for communicating with the retarded-side oil chamber R is formed with respect to the formed engagement recess 48, and with respect to the engagement recess 38 formed in the rotor housing 3 (rear end member 33). Oil passages 37 and 47 for communicating with the advance side oil chamber A are formed.
[0037]
According to the variable valve timing mechanism 1 of the present embodiment having the above-described configuration, as shown in FIG. 5B, when the intake side vane rotor 4 and the exhaust side vane rotor 5 are respectively in the initial positions, the lock is performed. Since the pin member 7 passes through the exhaust side vane rotor 5 and engages with each of the intake side vane rotor 4 and the rotor housing 3, the intake side vane rotor 4 in the middle of the rotation range is moved by the lock pin member 7. It can be securely fixed at the initial position.
[0038]
When the intake advance angle control is started, the hydraulic oil is introduced into the retarded-side oil chamber R and the hydraulic oil is discharged from the retarded-side oil chamber A from the initial state where both the vane rotors 4 and 5 are in the initial positions. Thus, as shown in FIG. 5A, first, hydraulic pressure acts on the engaging recess 48 of the intake side vane rotor 4 from the retarded side oil chamber R through the oil passage 46, and the lock pin 7a enters and locks. Only the intake side vane rotor 4, which is released from the engagement between the pin member 7 and the intake side vane rotor 4, is moved to the advanced position in the rotor housing 3 by the hydraulic pressure from the retard side oil chamber R. Move up.
[0039]
When the intake / exhaust simultaneous retarding 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 in the initial position, and the hydraulic oil is introduced from the retard side oil chamber R. By being discharged, as shown in FIG. 5C, first, hydraulic pressure acts on the engaging recess 38 of the rotor housing 3 (rear end member 33) from the advance side oil chamber A through the oil passages 47 and 37. Thus, the lock pin 7b is inserted and the engagement between the lock pin member 7 and the rotor housing 3 (rear end member 33) is released, and then the intake side vane rotor 4 and the exhaust side vane rotor 5 connected by the lock pin member 7 are released. Are moved to the retard position in the rotor housing 3 by the hydraulic pressure from the advance side oil chamber A.
[0040]
FIG. 7 shows the timing operation of the intake and exhaust valves. In the figure, (D) shows a one-stage chain layout in which the crankshaft and the intake and exhaust camshafts are connected by a single timing chain, and (E) shows the connection between the crankshaft and the exhaust camshaft by a primary chain. 2 shows an exhaust side two-stage chain layout in which an exhaust camshaft and an intake camshaft are connected by a secondary chain. (F) shows a crankshaft and an intake camshaft connected by a primary chain and an intake camshaft by a secondary chain. And an intake side two-stage chain layout in which the exhaust camshaft is connected. The above (D) and (E) show conventional examples in which variable valve timing mechanisms are arranged on the intake and exhaust camshafts, respectively, and (F) shows the present embodiment in which variable valve timing mechanisms are arranged only on the intake camshafts. The form is shown. Further, (a) shows the intake / exhaust simultaneous retarding operation, (b) shows the initial position state, and (c) shows the intake advance operation.
[0041]
For example, when the engine operation region is in a low load low rotation region or a high load high rotation region, the rotational phases of both the exhaust camshaft and the intake camshaft are held at the initial position with a phase angle of 0 degrees (initial b). When the vehicle is in the middle load and middle speed range, the rotational phases of the exhaust camshaft and the intake camshaft are retarded by α (simultaneous retard a) in order to improve fuel efficiency. When in the high load and low rotation range, the rotation phase of the intake camshaft is advanced by β in order to improve torque (advance c).
[0042]
On the other hand, in the variable valve timing mechanism 1 of this embodiment, as already described, the intake side vane rotor 4 and the exhaust side vane rotor 5 are operated in conjunction during the simultaneous intake and exhaust retard control, and the intake side during the intake advance control. In order to operate only the vane rotor 4, a stopper pin 55 and a stopper pin receiving portion 45 are formed for each of the vane rotors 4 and 5.
[0043]
However, when only the stopper pin 55 and the stopper pin receiving portion 45 are used, for example, when the intake and exhaust simultaneous retarding control is performed, the load from the intake camshaft side and the exhaust camshaft side is different. When the vane rotors 4 and 5 are moved from the initial position after starting the control, the exhaust side vane rotor 5 starts operating earlier than the intake side vane rotor 4, or the control is ended and When the vane rotors 4 and 5 return to the initial positions, the intake side vane rotor 4 starts operating earlier than the exhaust side vane rotor 5 so that the control timing between the intake side and the exhaust side may be shifted. There is a possibility.
[0044]
On the other hand, in the present embodiment, at the time of simultaneous intake / exhaust retard control, the intake side vane rotor 4 and the exhaust side vane rotor 5 are completely coupled by the lock pin member 7, and both of them operate in either direction. For example, even when the load from the intake camshaft side and the exhaust camshaft side is different, the control timing is different between the intake side and the exhaust side. It is possible to control the retard at the same time without causing any deviation. In particular, at the time of retardation control for changing the rotation phase in the direction opposite to the engine rotation direction, the retardation control can be surely performed by cooperating the two vane rotors 4 and 5.
[0045]
In the above embodiment, the case where the variable valve timing mechanism is arranged on the intake cam shaft has been described. However, in the variable valve timing mechanism outside the scope of the present invention, the mechanism can be arranged on the exhaust cam shaft. In this case, the intake camshaft can be turned only to the advance side, and the exhaust side can be turned to both the retard side and the advance side.
[0046]
Further, as shown in FIG. 8, when a single-stage chain layout in which the crankshaft is connected to the intake camshaft 2 and the exhaust camshaft 20 via cams plots 71 and 72 by a single timing chain 70, the intake camshaft 2 It is also possible to mount a variable valve timing mechanism 75 similar to the above embodiment. In this case, a variable valve timing mechanism 75 in which the first and second vane rotors 4 and 5 are housed in the rotor housing 3 is arranged on the intake camshaft 2 side, and a variable valve timing mechanism in which one vane rotor 77 is housed in the housing 76. 78 is arranged on the exhaust camshaft 20 side. The intake camshaft 2 can be rotated relative to both the retard side and the advance side from the illustrated initial position, and the exhaust camshaft 20 can be pivoted only from the initial position to the retard side.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of main components of a variable valve timing mechanism of a valve gear according to an embodiment of the present invention.
FIG. 2 is a sectional view of the variable valve timing mechanism.
3 is a sectional view of the first vane rotor of the variable valve timing mechanism (a sectional view taken along line III-III in FIG. 2).
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 view showing a retard angle and advance angle operation of each vane rotor.
FIG. 6 is a schematic front view of a V-type four-cycle engine provided with the variable valve timing mechanism.
FIG. 7 is a view showing a retard angle and advance angle operation 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 one-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)

The intake and exhaust valves are opened and closed via an intake camshaft that is rotated by a crankshaft and an exhaust camshaft that is rotated by the intake camshaft, and the intake and exhaust valves are opened and closed. In the variable valve timing mechanism of the valve operating apparatus that variably controls the timing according to the operating state of the engine,
A rotor housing to which rotation of the crankshaft is transmitted is mounted on the intake side camshaft so as to be relatively rotatable, and the intake side and exhaust side vane rotors are relatively rotatable with respect to the rotor housing and coaxially within the rotor housing. Furthermore, it is arranged so that the same hydraulic pressure acts ,
Fixing the intake side vane rotor to the intake side camshaft, connecting the exhaust side vane rotor to the exhaust camshaft to rotate together,
Both the intake side and exhaust side vane rotors are positioned at the initial position by fixing them to the rotor housing, and both the intake side and exhaust side vane rotors are retarded from the initial positions by releasing the fixing to the rotor housing. Switch between the intake / exhaust simultaneous retard position to be moved to the side and the intake advance position to rotate the intake side vane rotor from the initial position to the advance side by releasing the fixing to the rotor housing. A variable valve timing mechanism for a valve operating apparatus, comprising phase switching means for rotating.  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 the retard side or the advance side by hydraulic pressure, and rotates the exhaust side vane rotor from the initial position to the retard side. And a lock pin member for fixing the intake side and exhaust side vane rotors to each other, or fixing both the vane rotors to a rotor housing, and the lock pin member at the initial position for the intake side and exhaust side. Move both vane rotors so that they are fixed to the rotor housing, and move them so that the intake and exhaust vane rotors are fixed to each other at the simultaneous intake and exhaust retard positions, and fix the intake side vane rotor to the rotor housing at the intake advance position. A variable valve timing mechanism for a valve operating device, comprising a lock pin switching mechanism for releasing.

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