JP3211713B2 - Variable valve timing mechanism for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve timing mechanism for an internal combustion engine that changes at least one of an intake valve and an exhaust valve of the internal combustion engine in accordance with the operating state of the internal combustion engine.

[0002]

2. Description of the Related Art Hitherto, a variable valve timing mechanism for changing the valve timing of an intake valve or an exhaust valve in accordance with the operating state of an engine has been put to practical use. As this type of variable valve timing mechanism, for example, by changing the rotation phase (displacement angle) of a camshaft with respect to a crankshaft, the valve timing of a valve that is opened and closed with the rotation of the camshaft is changed. A known mechanism is known.

[0003] For example, Japanese Patent Application Laid-Open No. Hei 1-292504 discloses that a valve pull timing is changed by relatively rotating a timing pulley rotating in synchronization with a crankshaft and an internal rotor connected to a camshaft. The illustrated variable valve timing mechanism is shown. This variable valve timing mechanism will be described with reference to FIG.

The variable valve timing mechanism 90 includes a timing pulley 91 and an internal rotor 92. The timing pulley 91 has a plurality of oil grooves 912 between a plurality of protrusions 911 formed on the inner surface thereof. Also,
The internal rotor 92 is provided in each oil groove 9 of the timing pulley 91.
12 are provided with vanes 921. Pressure chambers 93 are formed on both sides of each vane 921, respectively. The timing pulley 91 is connected to a crankshaft via a timing belt (not shown), and the internal rotor 92 is connected to a camshaft 94.

[0005] Oil is supplied to each pressure chamber 93 through a passage 96 in the camshaft 94 and a passage 97 in the internal rotor 92. The internal rotor 92 and the camshaft 94 are integrally rotated by holding the vanes 921 by the pressure in the pressure chambers 93 on both sides of each vane 921.

The two opposing projections 911 each have a long hole 913 extending in the radial direction, and a lock pin 95 is accommodated in each long hole 913. Each lock pin is urged toward the axis of the timing pulley 91 by a spring 951.

On the other hand, the internal rotor 92 is
When each vane 921 is disposed at the most displaced position where it engages with any one inner wall of each oil groove 912, one of the lock pins 95 presses the biasing force of the spring 951. With this, it engages with the engagement hole 922. When oil is supplied to the passage 97 and the urging force of the pressure exceeds the urging force of the spring 951, the lock pin 9
5 and the engagement hole 922 are released.

In such a variable valve timing mechanism 90, since no oil pressure is generated when the engine is started, the lock pin 95 is engaged with the engagement hole 922 by the urging force of the spring 951, and the vane 921 is in the most displaced position. Locked. As a result, the relative rotation between the timing pulley 91 and the internal rotor 92 is regulated, and the valve timing is changed to the most retarded side (hereinafter, referred to as “most retarded valve timing”) or the most advanced side. It is held at the changed timing (hereinafter, referred to as “most advanced valve timing”).

On the other hand, when a sufficient oil pressure is generated during operation of the engine, the lock pin 95 is disengaged from the engagement hole 922 against the urging force of the spring 951 due to the oil pressure acting on the lock pin 95. . When a difference occurs between the oil pressures in the two pressure chambers 93 on both sides of the vane 921, the vane 921 moves toward the pressure chamber 93 having a low oil pressure, and the timing pulley 91 and the internal rotor 92 relatively rotate. . The relative rotation of the timing pulley 91 and the internal rotor 92 as described above causes the internal rotor 9 to rotate.
2, a phase difference occurs between the rotation phase of the camshaft 94 connected to the engine 2 and the reference rotation phase of the engine, that is, the rotation phase of the crankshaft. Therefore, the valve timing with respect to the crank angle is changed to the advance side or the retard side.

[0010]

By the way, with respect to each valve timing of the intake valve or the exhaust valve, there is a timing suitable for starting the engine, and the valve timing of each valve at the time of starting is determined by the following. If the timing is significantly different from the preferred timing, the startability is impaired.

For example, in an engine provided with a variable valve timing mechanism for changing the valve timing of an intake valve, if the valve timing is excessively changed to the retard side when the engine is started, the closing timing of the intake valve is delayed. Therefore, the intake air-fuel mixture in the combustion chamber returns to the intake pipe. If the intake air-fuel mixture returns into the intake pipe at the time of cranking at an extremely low engine speed, the actual compression ratio decreases, and starting becomes difficult. In particular, at a low temperature where the volume of the air-fuel mixture is small, even when cranking, the air-fuel mixture is not sufficiently compressed, and the startability is further deteriorated.

On the other hand, if the valve timing is changed to the advanced side too much when the engine is started, the valve overlap period becomes longer, and the internal EGR amount (exhaust gas circulation amount) in the combustion chamber increases. This will lead to a decrease in startability.

Similarly, even in an engine having a variable valve timing mechanism for changing the valve timing of the exhaust valve, if the valve timing is excessively changed to the retard side, the valve overlap period becomes longer. As a result, the internal EGR amount increases, which causes a decrease in engine startability.

If the valve timing of the exhaust valve is excessively changed to the advanced side at the time of starting the engine, the opening timing of the exhaust valve is advanced, and the opening period of the exhaust valve in the explosion stroke becomes longer. As a result, the explosion pressure in the combustion chamber cannot be sufficiently utilized, and the startability is reduced.

As described above, since there is a valve timing suitable for starting the engine, the variable valve timing mechanism 90 has the most retarded valve timing or the most advanced valve timing which is the valve timing at the time of starting. It is necessary that the valve timing is set to a timing that does not impair the startability.

However, when the most retarded or most advanced valve timing is set as described above, the variable region of the valve timing is restricted, and the valve timing is more appropriately adjusted to the operating state of the engine. There was a problem that the timing could not be further changed.

For example, when the valve timing of the intake valve is held at the most retarded valve timing at the time of starting the engine, the valve timing is further delayed than the valve timing suitable for starting at the time of high engine rotation. It cannot be changed to the corner side to increase the volumetric efficiency. That is, if the closing timing of the intake valve is further delayed, such an effect can be obtained in the above-described configuration, although the engine output can be improved by increasing the volumetric efficiency due to the intake inertia effect. Will not be.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a variable valve timing of an internal combustion engine capable of ensuring a startability of the internal combustion engine and expanding a variable range of valve timing. It is to provide a mechanism.

[0019]

According to a first aspect of the present invention, there is provided a first rotating body having at least one concave portion therein, and a concave portion having a first pressure chamber and a second pressure chamber. A second rotating body having a plurality of vanes partitioned into a first rotating body and being rotatably combined with the first rotating body; and synchronously rotating one of the first rotating body and the second rotating body at a reference rotation phase of the internal combustion engine. A drive shaft to be driven, a driven shaft interlocked with the other of the first rotating body or the second rotating body, and a valve selectively driven to a valve opening position or a valve closing position by the driven shaft. The first rotating body and the second rotating body are relatively rotated by the pressure applied to the chamber and the second pressure chamber, and by changing the rotation phase of the driven shaft with respect to the reference rotation phase of the internal combustion engine, Valve timing of the driven valve In the variable valve timing mechanism of the internal combustion engine, when the internal combustion engine is started, the vane is held at a position corresponding to the start of the internal combustion engine which is located substantially in the middle of the concave portion, and the relative position between the first rotary body and the second rotary body is changed. It is intended to further comprise a relative rotation restricting means for restricting the rotation and releasing the restriction after a lapse of a predetermined time from the start of the internal combustion engine.

According to the above configuration, the drive shaft synchronously rotates one of the first rotating body and the second rotating body at the reference rotation phase of the internal combustion engine. Since the first rotating body and the second rotating body are combined, the other of the first rotating body or the second rotating body is also synchronously rotated at the reference rotation phase,
Further, the driven shaft is also rotated synchronously with the reference rotation phase.

Here, the first rotator and the second rotator are combined so as to be able to rotate relative to each other.
When a pressure difference is generated between the pressure applied to the pressure chamber and the pressure applied to the second pressure chamber, and the vane moves to the lower pressure chamber of the two pressure chambers, the first rotating body and the second rotating body move. It rotates relative to the body. Due to this relative rotation, a phase difference occurs between the rotation phase of the first rotator and the rotation phase of the second rotator.

Accordingly, the rotational phase of the drive shaft and one of the first rotating body and the second rotating body is the same as that of the first rotating body and the second rotating body.
The phase difference generated by the relative rotation with the rotating body is changed and transmitted to the other first rotating body or the second rotating body. Further, the rotation phase of the driven shaft connected to the other of the first rotating body or the second rotating body is also changed,
This is different from the reference rotation phase. As a result, the valve timing of the valve driven by the driven shaft is changed from the valve timing based on the reference rotation phase to the valve timing based on the rotation phase changed by a phase difference.

When the internal combustion engine is started, the relative rotation restricting means holds the vane at a position corresponding to the start of the internal combustion engine, which is located substantially in the middle of the concave portion, and controls the relative rotation between the first rotary body and the second rotary body. Regulate movement. Therefore, the first rotating body and the second rotating body do not rotate relative to each other when the internal combustion engine is started, so that a predetermined valve timing suitable for starting is always realized.

On the other hand, the relative rotation restricting means releases the restriction of the relative rotation of the two rotating bodies after a lapse of a predetermined time from the start of the internal combustion engine. That is, the vane held at the starting position substantially at the center of the recess can be moved from that position. Therefore, by moving the vane in accordance with the pressure in both pressure chambers and rotating both rotating bodies relatively,
The valve timing can be further changed from the valve timing suitable for starting the engine to both the advance side and the retard side.

[0025]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a variable valve timing (VVT) mechanism for an internal combustion engine according to the present invention;

An engine 70 shown in FIG. 1 includes an intake camshaft 15 as a driven shaft, an exhaust camshaft 71, and a crankshaft 72 as a drive shaft, and these shafts 15, 71, 72 are sprockets 11, 7, respectively.
3, 74 and a chain 75. 2
One idler 76 applies tension to the chain 75. The VVT mechanism 10 in the present embodiment is provided on the intake camshaft 15. When the crankshaft 72 rotates, the camshafts 15 and 71 are rotated in synchronism with the crankshaft 72 via the chain 75 and the sprockets 11, 73 and 74, and the intake valve 77 and the exhaust valve 78 are moved to predetermined positions. It is opened and closed with the valve timing.

As shown in FIGS. 2 to 5, the VVT mechanism 10
Are sprocket 11, rotor 12, front cover 1
3, a rear plate 14 and an intake-side camshaft 15.

The intake-side camshaft 15 has a plurality of journals 151 (only one is shown), and as shown in FIG.
The journal 151 located at the tip of the camshaft 15 has a pair of flanges 151a and 151b. And
The camshaft 15 has a cylinder head 79 and a bearing cap 80 between the flanges 151a and 151b.
Are supported rotatably.

The rear plate 14 has a disk portion 141 and a boss 142, and a concave portion 141 formed in the disk portion 141.
At a, it is fitted to the front flange 151a. The engagement pin 31 protrudes forward from the flange 151 a of the camshaft 15 and is engaged with the pin hole 147 of the disk 141. Therefore, the rear plate 14 rotates integrally with the camshaft 15.

The rotor 12 has a stepped through hole 1 at its axis.
21 and four vanes 122 protruding radially at equal angular intervals on the outer periphery thereof. Rotor 12
Is mounted on the boss 142 of the rear plate 14 at the through hole 121. In addition, a plurality of engagement pins 30
(Only one is shown) is planted in the pin hole 146 of the disk portion 141 of the rear plate 14 and protrudes forward, and is engaged with the pin hole 127 of the vane 122, respectively. Therefore, the rotor 12 is connected to the rear plate 14 and the camshaft 1.
5 and rotate together. Further, the boss 142 and the rotor 1
2, a seal 149 is disposed between the two.
The space between the two is sealed.

The sprocket 11 has a substantially cylindrical shape, and is arranged on the outer periphery of the disk portion 141 of the rear plate 14 and the outer periphery of the rotor 12. The sprocket 11 is connected to the disk 14
1 has a concave portion 116 having a shape corresponding to the outer diameter of the concave portion 1.
At 16, it is supported so as to be relatively rotatable along the outer periphery of the disk portion 141. In addition, the sprocket 1 in this embodiment
1 rotates clockwise in FIG. 3 with the rotation of the crankshaft 72 when the engine 70 is in the operating state.

The front cover 13 is relatively rotatably mounted on the outer periphery of the sprocket 11 so as to cover the front surface of the sprocket 11 and the front surface of the rotor 12, and is fixed to the camshaft 15 by bolts 32. Therefore,
The front cover 13, the rotor 12, the rear plate 14, and the camshaft 15 can be integrally rotated.

A plurality of teeth 112 are formed on the outer periphery of the sprocket 11 so as to correspond to the concave portions 116 of the sprocket 12, and the chain 75 is formed on the outer periphery of the teeth 112.
Is hung. On the inner periphery of the sprocket 12, four convex portions 115 protruding toward the center are formed at equal angular intervals. Four concave portions 114 for accommodating the vanes 122 of the rotor 12 and a space for accommodating the cylindrical portion of the rotor 12 are formed between the convex portions 115. When each vane 122 is arranged in each recess 114, the advance chamber 101 and the retard chamber 102 are formed on both sides of each vane 122.

A sealing member 1 is provided on the outer end face of each vane 122.
23 is mounted and pressed against the inner wall surface of each recess 114 by a leaf spring 124. Therefore, each seal member 123
Thereby, the advance chamber 101 and the retard chamber 102 are sealed. In a state where oil is supplied into both chambers 101 and 102, the rotor 12 and the sprocket 11 are connected by the pressure of the oil, and the rotation of the sprocket 11 is transmitted to the rotor 12 via the oil.
2, the camshaft 15 is rotated.

When the pressure in the retard chamber 102 becomes greater than the pressure in the advance chamber 101, each vane 122 rotates counterclockwise in FIG. 3 and engages with the inner wall of the corresponding convex portion 115. At this time, the camshaft 15 is disposed at the most retarded position with respect to the crankshaft. Conversely, the pressure in the advance chamber 101 becomes larger than the pressure in the retard chamber 102, and each vane 122 rotates clockwise in FIG.
When engaged with the inner wall of the camshaft 15, the camshaft 15 is disposed at the most advanced position with respect to the crankshaft 72.

As shown in FIGS.
One of the protrusions 115 is formed with a stepped accommodation hole 117 extending parallel to the axis of the camshaft 15. The rear plate 1 is positioned so as to be able to face the accommodation hole 117.
A lock recess 145 is formed in the fourth disk portion 141. The lock recess 145 has an elliptical shape along the radial direction.

The receiving hole 117 has a large diameter portion 117a and a small diameter portion 1a.
17b. The lock pin 20 has a large-diameter portion 22 located forward and a small-diameter portion 21 located rearward, and is slidably inserted into the stepped hole 117. The large diameter part 22 of the lock pin 20 is the large diameter part 117a of the accommodation hole 117.
The small diameter portion 21 of the lock pin 20 is set longer than the small diameter portion 117b of the housing hole 117. Therefore, a ring-shaped pressure chamber 181 is formed between the large diameter portion 22 of the lock pin and the small diameter portion 117b of the housing hole 117.

The pressure of the oil supplied to the pressure chamber 181 acts on the step of the lock pin 20, that is, the first pressure receiving surface 25. On the other hand, the rear end surface of the small diameter portion 21 of the lock pin 20 forms a second pressure receiving surface 26. In addition, the lock pin 20
Is urged by a spring 24 interposed between the large-diameter portion 22 and the front cover 13 in a direction in which the lock recess 145 is engaged. Therefore, the urging force acting on each pressure receiving surface 25, 26 by the oil pressure is applied to the spring 24.
When the lock pin 20 is smaller than the urging force of
4 engages the front or locking recess 145.

When a relative rotation occurs between the sprocket 11 and the rear plate 14 in a state where the lock pin 20 is engaged with the front surface of the disk portion 141, when the lock pin 20 is opposed to the lock recess 145, It engages with the lock recess 145. At this time, the sprocket 11 is
4 is mechanically connected.

Further, the lock pin 20 is locked with the lock recess 145.
3, the rotor 12 is arranged at the position shown in FIG. 3, and each vane 122 is arranged at a position separated from the most retarded position by a predetermined angle α toward the advance side.

Conversely, when the urging force acting on each pressure receiving surface 25, 26 due to the oil pressure is greater than the urging force of the spring 24, the lock pin 20 separates from the front surface of the disk portion 14, and the sprocket 11 and rear plate 14
Is allowed to rotate. At this time, since the lock pin 20 is immersed in the accommodation hole 117,
No wear due to contact with

Next, an oil supply path to the advance chamber 101, the retard chamber 102, and the first and second pressure receiving surfaces 25 and 26 of the lock pin 20 will be described. A cross-shaped advance passage 125 is formed on the front surface of the rotor 12 so as to communicate with each advance chamber 101 (see FIG. 2). On the other hand, FIG.
As shown in FIG. 5, on the outer periphery of the journal 151, an annular advance groove 81 is formed on the inner peripheral surfaces of the cylinder head 79 and the bearing cap 80, and the advance groove 81 is formed.
Is the passage 82 and the oil control valve (OCV) 4
0 is connected to a hydraulic pump 46. The hydraulic pump 46 is a mechanical pump driven by rotation of a crankshaft 72.

A substantially L-shaped connection passage 155 is formed inside the journal 151, and the boss 142 and the bolt 3
An air gap 143 is provided between the first and second air conditioners. The advance groove 81 is connected to the advance chamber 101 by the connection passage 155, the gap 143, and the advance passage 125.
Therefore, the passage 8 from the hydraulic pump 46 through the OCV 40
2 is supplied to the advance groove 81 and the connection passage 15.
5, advance chamber 10 through space 143 and advance passage 125
1 is supplied.

On the other hand, to communicate with each of the retard chambers 102,
A cross-shaped retard passage 126 having substantially the same shape as the advance passage 125 is formed on the rear surface of the rotor 12 (see FIGS. 2 and 5). An annular retard groove 157 is formed on the outer periphery of the journal 151, and the retard groove 157 is formed in the passage 83.
And an OCV 40 to a hydraulic pump 46.

Further, inside the journal 151, a linear connection passage 15 extending parallel to the axis of the cam shaft 15 is provided.
6 are formed, and the connection passages 15 are formed in the rear plate 14.
6 and an intermediate passage 84 communicating with the retard passage 126. Therefore, oil supplied from the hydraulic pump 46 to the passage 83 via the OCV 40 is supplied to the retard chamber 102 via the retard groove 157, the connection passage 156, the intermediate passage 84 and the retard passage 126.

As shown in FIG. 3, the pressure chamber 181 in the housing hole 117 is connected to the retard chamber 102 by a retard connection 119 formed on the side wall of the recess 115. Therefore, the pressure in the retard chamber 102 acts on the first pressure receiving surface 25 of the lock pin 20 via the connection path 119.

Also, as shown in FIGS.
7, a portion located rearward of the rear surface of the lock pin 20 is an advanced connection path 1 formed on the rear surface of the convex portion 115.
18 connects to the advance chamber 101. Therefore,
The pressure in the advance chamber 101 acts on the second pressure receiving surface 26 of the lock pin 20 via the connection path 118.

Also, as shown in FIG.
Is connected to the lock recess 145 via a radiation passage 144 formed in the rear plate 14 upstream of the advance passage 125. Therefore, the pressure of the oil supplied into the gap 143 acts on the second pressure receiving surface 26 of the lock pin 20 via the radiation passage 144.

The OCV 40 is a control valve for adjusting the amount of oil supplied to each of the chambers 101 and 102. OCV
40 has a casing 45, and the spool 44 is reciprocally accommodated in the casing 45. The electromagnetic actuator 41 has a plunger 43, which is in contact with a spool 44. The coil spring 42 in the casing 45 connects the spool 44 to the plunger 4.
It is biased to the 3 side.

The casing 45 of the OCV 40 has a tank port 45t, an A port 45a, a B port 45b, and a pair of reservoir ports 45r. The tank port 45t is connected to an oil pan 47 via a hydraulic pump 46. The A port 45a is connected to the advance groove 81 via the passage 82, and the B port 45b is connected to the passage 83
Is connected to the retard groove 157 via the. The reservoir port 45r is connected to the oil pan 47.

The spool 44 is a cylindrical valve body and moves against or assisted by the urging force of the spring 42 based on the duty control of the actuator 41. The spool 44 includes a plurality of lands 44a.
Two ports (45a, 4a) are provided by a plurality of lands 44a.
5t), (45a, 45r), (45b, 45t),
The oil flow between (45b, 45r) is shut off. The spool 44 includes a plurality of passages 44b and 44c between the lands 44a.
The two ports (45a, 45t), (45a, 45r), and (4c)
5b, 45t) and (45b, 45r).

When the engine is stopped, the hydraulic pump 46
The CVs 40 are both kept stopped. Therefore,
No oil is supplied to the advance chamber 101 and the retard chamber 102, and no oil pressure is applied to the lock pin 20.
Also, when the engine 70 is started, that is, at the time of cranking, sufficient hydraulic pressure is not generated. As a result, the lock pin 20 is pushed by the urging force of the spring 24 so that the lock recess 145 of the rear plate 14 or the rear plate 14
Is engaged with the front surface.

When the sprocket 11 is rotated with cranking, the lock pin 20 moves on the rear plate 14 and engages with the lock recess 145. In this state, the sprocket 11 is locked to the rear plate 14, so that the sprocket 11, the rotor 12, the rear plate 14, and the camshaft 15 are mechanically connected.
Therefore, when the engine 70 is started, the sprocket 1
In other words, the rotational phase of the camshaft 15 with respect to the crankshaft 72 is not changed.

In this embodiment, when the lock pin 20 is engaged with the lock recess 145 of the rear plate 14, the phase of the cam shaft 15 is determined mechanically. The phase is shifted to the advance side by a predetermined angle α from the phase that realizes the valve timing of the most retarded angle, and is set to a phase that can realize the optimal valve timing for starting the engine.

On the other hand, after the engine 70 is started, when the hydraulic pump 46 generates a sufficient hydraulic pressure and the spool 44 is moved to the left in FIG. 4 by the actuator 41, the passage 44b becomes the tank port 45t. And the A port 45a (hereinafter, the position of the spool 44 is referred to as “advanced position”). As a result, the engine oil is supplied to the advance groove 81 with the operation of the hydraulic pump 46.
This oil is supplied to the connection passage 155 in the journal 151,
The oil is supplied to the advance chamber 101 through the space 143 and the advance passage 125, and the hydraulic pressure in the advance chamber 101 increases.

At the same time, the passage 44c connects the B port 45b and the reservoir port 45r. As a result, the oil in the retard chamber 102 passes through the retard passage 126 of the rotor 12, the intermediate passage 84 of the rear plate 14, the connection passage 156 of the journal 151, the retard groove 157 and the passage 83, and the B port 45b of the OCV 40. Then, the oil is discharged to the oil pan 47 via the reservoir port 45r. Therefore, the hydraulic pressure in the retard chamber 102 decreases.

The oil passing through the gap 143 upstream of the advance chamber 101 is supplied to the lock pin 2 via the radiation passage 144.
0 acts on the second pressure receiving surface 26. The oil supplied into the advance chamber 101 acts on the second pressure receiving surface 26 of the lock pin 20 via the connection path 118. And the advance chamber 1
When the supply amount of oil to the oil pressure 01 increases and the pressure acting on the second pressure receiving surface 26 exceeds the urging force of the spring 24,
The lock pin 20 is stored in the accommodation hole 117 at a distance from the lock recess 145. Therefore, smooth relative rotation between the rotor 12 and the sprocket 11 is allowed.

When the pressure in the advance chamber 101 increases and the pressure in the retard chamber 102 decreases, based on the pressure difference between the advance chamber 101 and the retard chamber 102 located on both sides of each vane 122, The rotor 12 rotates clockwise in FIG. Therefore, a rotational force is applied to the intake-side camshaft 15 via the rear plate 14. As a result, the rotation phase of the intake-side camshaft 15 with respect to the sprocket 11, that is, the crankshaft 71 is changed, and the camshaft 15 rotates from the lock position to the advance side. The rotation of the camshaft 15 advances the valve timing of the intake valve 77.

As described above, the intake valve 77 whose valve timing is advanced is opened while the exhaust valve 78 is open, and the valve overlap period during which the intake valve 77 and the exhaust valve 78 are simultaneously opened is extended. You.

On the other hand, after the engine is started, when the spool 44 is moved rightward in FIG. 4 by the actuator 41, the passage 44b becomes the tank port 45t and the B port 4t.
5b (hereinafter, the position of the spool 44 is referred to as a "retard position"). In this state, the oil is supplied to the retard groove 157 by the operation of the pump 46. Then, the oil is supplied to the retard chamber 102 via the passage 83, the retard groove 157, the connection passage 156, the intermediate passage 84, and the retard passage 126. As a result, the pressure in the retard chamber 102 increases.

At the same time, the passage 44c connects the A port 45a and the reservoir port 45r. As a result, the oil in the advance chamber 101 flows into the advance passage 125, the gap 143, and the connection passage 1 in the journal 151 of the rotor 12.
55, through the advance groove 81 and the passage 82,
The oil is discharged to the oil pan 47 via the port 45a and the reservoir port 45r. Therefore, the pressure in the advance chamber 101 decreases.

The oil supplied to the retard chamber 102 is supplied to the lock pin 20 through a connection passage 119 shown in FIG.
Acts on the first pressure receiving surface 25. When the urging force due to the oil pressure exceeds the urging force of the spring 24,
The lock pin 20 is stored in the accommodation hole 117 while being separated from the lock recess 145. Therefore, smooth relative rotation between the rotor 12 and the sprocket 11 is allowed.

Thereafter, the pressure in the retard chamber 102 increases,
When the pressure in the advance chamber 101 decreases, each vane 12
The rotor 12 rotates counterclockwise in FIG. 3 based on the pressure difference between the retard chamber 102 and the advance chamber 101 located on both sides of the rotor 2. Therefore, a rotational force is applied to the intake-side camshaft 15 via the rear plate 14. as a result,
The rotation phase of the intake camshaft 15 with respect to the sprocket 11, that is, the crankshaft 72, is changed, and the intake camshaft 15 rotates from the lock position to the retard side.
Then, the valve timing of the intake valve 77 driven by the intake side camshaft 15 is delayed, and the valve overlap period is reduced or eliminated.

Since the lock recess 145 of this embodiment is formed in an elliptical shape along the radial direction, when the rotor 12 and the rear plate 14 rotate to the retard side, the lock recess 145 becomes the retard chamber. There is no communication with 102. Rotor 1
When the rear plate 2 and the rear plate 1 rotate to the advance side, the lock recess 145 communicates with the advance chamber 101. However, the lock recess 145 communicates with the advance chamber 101 via the gap 143 and the radiation passage 144, so that the flow of oil is not hindered.

Further, after the engine is started, when the spool 44 is moved by the OCV 40 to a substantially intermediate position between the aforementioned "advanced position" and "retarded position", the A port 45
Both the port a and the port B 45b are closed by the land 44a (hereinafter, the position of the spool 44 at this time is referred to as a "holding position"). Accordingly, oil is supplied to the advance chamber 101 and the retard chamber 102, and both the chambers 101 and 10 are supplied.
The discharge of oil from 2 is stopped. As a result, the relative rotation of the camshaft 15 with respect to the sprocket 11 is stopped, and the valve timing of the intake valve 177 is maintained at the current timing.

In the VVT mechanism 10 of the present embodiment,
The target phase angle of the camshaft 15 calculated based on the operation state of the engine 70 is compared with the actually detected actual phase angle, and the position of the spool 44 of the OCV 40 is advanced based on the difference between the two phase angles. Angular position ”,“ retarded position ”, and“ holding position ”as appropriate to adjust the intake valve 1
The valve timing of the valve 77 can be continuously changed to the advance side and the retard side, and the changed state can be maintained. Further, the valve overlap period can be continuously changed with the change of the valve timing.

In this embodiment, as shown in FIG. 6B, when the engine is started, the sprocket 11 is shifted from the phase for realizing the valve timing of the most retarded angle by a predetermined angle α toward the advance side. And the camshaft 15 are locked. Therefore, unlike the conventional variable valve timing mechanism in which the engine 70 is started at the most retarded position (see FIG. 6A), the valve timing during the operation of the engine is further retarded than the valve timing when the engine is started. Can be changed to

When the engine 70 stops, the hydraulic pump 46 stops, and the supply of oil to the engine 70 stops. Further, the spool 44 of the OCV 40 is stopped at a position where the port 45b communicates with the port 45t shown in FIG. 4, that is, at a position where the oil is supplied to the retard chamber 102 by the urging force of the spring 42. At this time, since the pump 46 is stopped, the oil in the retard chamber 102 is allowed to return to the oil pan 47. Further, since the spool 44 is stopped at the position shown in FIG. 4, the oil in the advance chamber 101 returns to the oil pan 47 via the port 45a and the port 45r.

When the oil returns, the oil pressure acting on the first pressure receiving surface 25 or the second pressure receiving surface 26 of the lock pin 20 also decreases, and the lock pin 20 is moved toward the rear plate 14 by the urging force of the spring 24. Be moved. On the other hand, when the engine is stopped, the rotor 1 and the camshaft 15 and the rear plate 14 are driven based on the reaction force from the intake valve 77.
2 rotates on the retard side, that is, the counterclockwise direction in FIG. With the rotation, when the lock concave portion 145 faces the lock pin 20, the lock pin 20 engages with the lock concave portion 145. As a result, the relative rotation between the rotor 12 and the sprocket 11 is restricted. When the two do not face each other, the lock pin 20 is maintained in a state of being engaged with the front surface of the rear plate 14.

As described above, the variable valve timing mechanism 10 of the internal combustion engine according to the present embodiment has a phase separated from the phase for realizing the valve timing of the most retarded angle by a predetermined angle α on the advance side. The relative rotation between the sprocket 11 and the camshaft 15 is restricted, and the engine 70 can be started in that phase. Therefore, by setting the predetermined angle α to an appropriate value, it is possible to ensure good starting characteristics of the engine 70.

Further, in this embodiment, the relative rotation between the sprocket 11 and the rear plate 14 is regulated by engaging the lock pin 20 in the lock recess 145. 14 can be more reliably restricted, and the lock pin 2
By the movement of 0, the regulation can be easily released.

Further, in the variable valve timing mechanism 10 of the internal combustion engine according to the present embodiment, during the operation of the engine 70, the valve timing can be changed to a more retarded side than the phase for starting the engine. for that reason,
In the high rotation range of the engine 70, a desired intake inertia effect can be obtained and the output characteristics can be improved. Furthermore, since the valve timing of the most retarded angle is not restricted by the valve timing at the time of starting the engine, it is possible to reduce the pumping loss, and as a result, it is possible to improve the fuel efficiency characteristics.

Further, in the present embodiment, it is possible to always apply hydraulic pressure to the lock pin 20 during a valve timing change period in which the rotor 12 and the sprocket 11 are kept rotatable relative to each other. Therefore, during the valve timing change period, the lock pin 20 is
The projections 17 do not protrude, so that wear of the lock pin 20 and the rear plate 14 due to contact between them can be prevented.

In this embodiment, the oil is supplied by connecting the pressure chamber 181, the lock recess 145, and the inside of the rear end of the housing hole 117 to the advance chamber 101 or the retard chamber 102. The position of the lock pin 20 is changed by the pressure and the urging force of the spring 24. Therefore, for example, as compared with a configuration in which the position of the lock pin 20 is changed by an actuator such as an electromagnetic solenoid, the number of components can be reduced and the configuration can be simplified.

Further, according to the present embodiment, the advance chamber 101
When the oil pressure supplied to the retard chamber 102 is not sufficient, that is, when the rotor 12 cannot be controlled to a predetermined rotation phase by the oil pressure of each of the chambers 101 and 102, the first pressure receiving surface 25 of the lock pin 20 and the 2 The oil pressure acting on the pressure receiving surface 26 is also necessarily reduced. Accordingly, when the oil pressure is not sufficient as described above, the lock pin 20 is always engaged with the lock recess 145 by the urging force of the spring 24, and the rotor 12 vibrates in the recess 114, and The problem that abnormal noise occurs due to collision with the inner peripheral wall of the portion 114 can be prevented beforehand.

The above embodiment can be implemented by changing the configuration as described below. Even if the configuration is changed in this way, the same operation and effect as the above embodiment can be obtained.

In the above embodiment, the VVT mechanism 10 is provided on the intake camshaft 15. On the other hand, a VVT mechanism may be provided on the exhaust-side camshaft 71, and the valve timing of the exhaust valve may be changed by the same mechanism. Further, a VVT mechanism may be provided on both the intake side camshaft 15 and the exhaust side camshaft 71 to change the valve timing of each of the intake valve and the exhaust valve.

In the above embodiment, each shaft 15, 7
Although the first and second wheels 72 are driven and connected by the sprockets 11, 73 and 74 and the chain 175, the first and second wheels may be driven and connected by a timing belt and a gear.

In the above embodiment, the intake camshaft 15, the exhaust camshaft 71, the crankshaft 72
And a chain 175 for each shaft 15, 7
1, 72 were driven and connected. On the other hand, in the VVT mechanism 10, the sprocket 11 is changed to a drive gear having a plurality of teeth on the outer periphery. The VVT mechanism is provided at one end of the exhaust camshaft.
On the other hand, a sprocket is provided at the other end of the exhaust-side camshaft. Then, a chain is hung on the sprocket and the sprocket of the crankshaft to drive and connect the exhaust side camshaft and the crankshaft. Further, a driven gear is provided at one end of the intake camshaft, and the driven gear is meshed with a drive gear of the exhaust camshaft. According to such a configuration, the V provided on the exhaust-side camshaft is
The valve timing of the intake valve can be changed by changing the rotation phase of the intake camshaft by the VT mechanism. In this configuration, the exhaust-side camshaft corresponds to the drive shaft of the present invention, and the intake-side camshaft corresponds to the driven shaft. In the above-described embodiment, the sprocket 11 has the accommodation hole 117 for accommodating the lock pin 20, and the rear plate 14 has the lock recess 145 with which the lock pin 20 is engaged. On the other hand, the accommodation hole of the lock pin may be provided in the rear plate that rotates together with the rotor, and the engagement hole may be provided in the sprocket.

In the above embodiment, the relative rotation between the sprocket 11 and the rear plate 14 is regulated by engaging the lock pin 20 with the lock recess 145. On the other hand, for example, the lock pin 20 is changed to a pressing member pressed against the front surface of the disk portion 141, and the relative rotation between the sprocket 11 and the rear plate 14 is regulated by the frictional force generated by the pressing. Is also good.

The technical idea grasped from the above embodiment will be described below together with its effects. (A) In the variable valve timing mechanism for an internal combustion engine according to claim 1, the relative rotation restricting means includes a first valve.
An engaging recess formed in one of the rotating body and the second rotating body is movably supported by the other of the first rotating body and the second rotating body. A detachable pin that engages with the engagement recess when the internal combustion engine is started and separates from the engagement recess after a lapse of a predetermined time from the start of the internal combustion engine. It is characterized by.

According to such a configuration, the relative rotation of the two rotating bodies can be more reliably restricted by the engagement between the pin and the engagement recess, and the restriction can be easily released by the movement of the pin. (B) In the variable valve timing mechanism for an internal combustion engine described in (a) above, the relative rotation restricting means includes an urging means for constantly urging the pin in a direction of engaging with the engaging recess. A pressure applied to at least one of the first pressure chamber and the second pressure chamber on the pressure receiving surface formed on the pin to release the pin from the engagement recess. Means is further provided.

According to such a configuration, the state of engagement and disengagement between the pin and the engagement recess is changed according to the magnitude of the pressure in the first pressure chamber or the second pressure chamber. Therefore, when the pressure in the first pressure chamber or the second pressure chamber is small and the pressure cannot control the relative rotation between the first rotating body and the second rotating body,
The pin is engaged with the engagement concave portion, so that the relative rotation of the two rotating bodies can be regulated, and the relative rotation of the two rotating bodies in an uncontrollable state can be suppressed.

[0084]

According to the present invention, relative rotation restricting means
When the internal combustion engine is started, the vane is held at a position corresponding to the start of the internal combustion engine, which is located substantially in the middle of the concave portion, to regulate the relative rotation between the first rotating body and the second rotating body, and to start the internal combustion engine. The regulation is released after a predetermined time has elapsed from the time.

Therefore, when the internal combustion engine is started, the valve timing is maintained at a predetermined valve timing suitable for starting. On the other hand, after a lapse of a predetermined time from the start, that is, after the start is completed, the first rotating body and the second rotating body can relatively rotate, and the valve timing is set to a valve timing suitable for starting the engine. Can be further changed to both the retard side and the advance side. As a result, according to the present invention, the startability of the internal combustion engine can be ensured, and the variable region of the valve timing can be expanded.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a schematic configuration of a variable valve timing mechanism of the internal combustion engine.

FIG. 3 is a front view of a variable valve timing mechanism of the internal combustion engine with a cover removed.

FIG. 4 is a sectional view taken along line 4-4 in FIG. 3;

FIG. 5 is a sectional view taken along the line 5-5 in FIG. 3;

FIG. 6 is an explanatory diagram showing an operation region of a variable valve timing mechanism.

FIG. 7 is a front view of a conventional variable valve timing mechanism.

[Explanation of symbols]

11 sprocket, 15 camshaft on intake side, 20
... lock pin, 24 ... spring, 70 ... engine, 7
2 ... crankshaft, 77 ... intake valve, 101 ... advance chamber, 102 ... retard chamber, 114 ... recess, 122 ... vane, 145 ... lock recess.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-9-60508 (JP, A) JP-A-9-209724 (JP, A) JP-A-61-87910 (JP, A) JP-A-7-107 238806 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) F01L 1/34

Claims (1)

(57) [Claims] 1. A first rotating body having at least one concave portion therein, and a plurality of vanes dividing the concave portion into a first pressure chamber and a second pressure chamber, and the first rotating member being relatively rotatable. A second rotating body combined with a body, a drive shaft for synchronously rotating one of the first rotating body or the second rotating body at a reference rotation phase of the internal combustion engine, and the first rotating body or the second rotating body. And a valve selectively driven to an open position or a closed position by the driven shaft, and a pressure applied to the first pressure chamber and the second pressure chamber. The first rotating body and the second rotating body are relatively rotated by the rotation of the internal combustion engine, and the rotation phase of the driven shaft with respect to a reference rotation phase of the internal combustion engine is changed. Change valve timing In the variable valve timing mechanism for an internal combustion engine, when the internal combustion engine is started, the vane is held at a position corresponding to the start of the internal combustion engine located substantially in the middle of the concave portion, and the first rotating body and the first A variable valve for an internal combustion engine, further comprising relative rotation restricting means for restricting relative rotation with respect to the two rotating bodies and releasing the restriction after a predetermined time has elapsed from the start of the internal combustion engine. Timing mechanism.