JPH09324613A - Variable valve timing mechanism for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure startability of an internal combustion engine and enlarge a variable area of a valve timing. SOLUTION: A variable valve timing(VVT) mechanism 10 for an internal combustion engine varies a valve timing of an intake valve. The VVT 10 has a sprocket drivingly connected to a crank shaft, a rear plate fixed to an intake cam shaft, and a rotor 12 fixed to the rear plate. Projections 115 are equally spaced on the sprocket and recessions 114 are formed between the projections 115. Each projection 115 has a housing hole 117 in which a lock pin 20 is slidably housed. The lock pin 20 is engaged with a lock recession 145 formed on a rear plate in the state that the rotor 12 is rotated in the phase advancing direction from the most phase lag position by a specified angle α, for regulating relative rotation between the sprocket and the rear plate.

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, which changes the valve timing of at least one of an intake valve and an exhaust valve of the internal combustion engine according to the operating state of the internal combustion engine.

[0002]

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

For example, Japanese Laid-Open Patent Publication No. 1-92504 discloses that a valve timing is changed by relatively rotating a timing pulley rotating in synchronization with a crankshaft and an internal rotor connected to a camshaft. A variable valve timing mechanism is shown. This variable valve timing mechanism will be described with reference to FIG.

The variable valve timing mechanism 90 comprises 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 includes the oil grooves 9 of the timing pulley 91.
The vane 921 arranged in 12 is provided. Pressure chambers 93 are formed on both sides of each vane 921. The timing pulley 91 is connected to the crankshaft via a timing belt (not shown), and the internal rotor 92 is connected to the camshaft 94.

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. Then, the vanes 921 are held by the pressure in the pressure chambers 93 on both sides of each vane 921, so that the internal rotor 92 and the cam shaft 94 are integrally rotated.

Further, each of the two projecting portions 911 facing each other has a slot 913 extending in the radial direction, and a lock pin 95 is housed in each slot 913. Each lock pin is biased toward the axis of the timing pulley 91 by a spring 951.

On the other hand, the internal rotor 92 has lock pins 95.
When the vanes 921 are arranged at the most displaced positions in which the respective vanes 921 engage with the inner walls of one of the oil grooves 912, any one of the lock pins 95 is urged by the spring 951. Is engaged with the engaging hole 922. When the oil is supplied to the passage 97 and the urging force due to the pressure exceeds the urging force of the spring 951, the lock pin 9
5 and the engagement hole 922 are disengaged.

In such a variable valve timing mechanism 90, since the oil pressure is not 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 at the most displaced position. It is locked. As a result, the relative rotation of the timing pulley 91 and the internal rotor 92 is restricted, and the valve timing is changed to the most retarded side (hereinafter referred to as the “most retarded valve timing”) or the most advanced side. It is held at the changed timing (hereinafter, referred to as "the most advanced valve timing").

On the other hand, when a sufficient oil pressure is generated with the operation of the engine, the oil pressure acting on the lock pin 95 causes the lock pin 95 to disengage from the engagement hole 922 against the biasing force of the spring 951. . Then, when a difference occurs in 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 in this manner causes the internal rotor 9 to rotate.
A phase difference is generated between the rotation phase of the camshaft 94 connected to the second shaft 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, there is a suitable timing for starting the engine for each valve timing of the intake valve or the exhaust valve, and the valve timing of each valve at the time of starting is as follows. If the timing is significantly different from the preferable timing, startability will be impaired.

For example, in an engine equipped with a variable valve timing mechanism for changing the valve timing of an intake valve, if the valve timing is changed too late when the engine is started, the closing timing of the intake valve will be delayed. Therefore, the intake air-fuel mixture in the combustion chamber returns to the intake pipe. When the intake air-fuel mixture returns to the inside of the intake pipe during cranking when the engine speed is extremely low, the actual compression ratio decreases, making it difficult to start the engine. In particular, at low temperatures where the volume of the air-fuel mixture is small, even if cranking is performed, the air-fuel mixture is not sufficiently compressed and the startability deteriorates.

On the other hand, if the valve timing is changed to the advance side too much at the engine start, the valve overlap period becomes long and the internal EGR amount (exhaust gas circulation amount) in the combustion chamber increases, so that the engine This leads to a decrease in startability.

Similarly, even in an engine equipped with a variable valve timing mechanism for changing the valve timing of the exhaust valve, if the valve timing is changed to the retard side too much, the valve overlap period becomes long. Therefore, the amount of internal EGR increases and the engine startability deteriorates.

Further, when the valve timing of the exhaust valve is excessively changed to the advance side at the engine start, the valve opening timing of the exhaust valve is advanced, and the valve opening period of the exhaust valve in the explosion stroke becomes long. As a result, the explosion pressure in the combustion chamber cannot be fully utilized, resulting in a decrease in startability.

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. The valve timing must be set to a timing that does not impair the startability.

However, when the most retarded or most advanced valve timing is set in this way, the variable range of the valve timing is limited, and the valve timing is more suitable for the operating condition of the engine. There was a problem that the timing could not be changed further.

For example, when the valve timing of the intake valve is kept at the most retarded valve timing when the engine is started, the valve timing is further delayed than the valve timing suitable for starting when the engine is running at high speed. The volume efficiency cannot be increased by changing to the corner side. That is, even if the closing timing of the intake valve is further delayed, it is possible to improve the engine output by increasing the volumetric efficiency due to the intake inertia effect, but in the above configuration, such an effect is obtained. There will be no.

The present invention has been made in view of the above circumstances, and an object thereof is to secure the startability of the internal combustion engine and to expand the variable range of the valve timing. To provide a mechanism.

[0019]

In order to achieve the above object, the invention according to claim 1 has a first rotating body having at least one recess therein, and a recess having a first pressure chamber and a second pressure chamber. And a second rotating body having a plurality of vanes that are partitioned into and a relatively rotatable combination with the first rotating body, and one of the first rotating body and the second rotating body is synchronously rotated at the reference rotation phase of the internal combustion engine. A first drive shaft, a driven shaft that works with the other of the first rotating body and the second rotating body, and a valve that is selectively driven by the driven shaft to a valve opening position or a valve closing position. By the pressure applied to the chamber and the second pressure chamber, the first rotating body and the second rotating body are relatively rotated to change the rotational phase of the driven shaft with respect to the reference rotational phase of the internal combustion engine. Valve timing of driven valve In the variable valve timing mechanism of the internal combustion engine to be changed, when the internal combustion engine is started, the vane is held at a position corresponding to the starting time of the internal combustion engine, which is located substantially in the middle of the recess, and the relative rotation between the first rotating body and the second rotating body. The purpose of the present invention is to further include a relative rotation restricting unit that restricts the rotation and releases the restriction after a predetermined time has elapsed from the start of the internal combustion engine.

According to the above structure, 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 at the reference rotation phase.

Here, the first rotating body and the second rotating body are combined so as to be capable of relative rotation,
When a pressure difference occurs between the pressure applied to the pressure chamber and the pressure applied to the second pressure chamber and the vane moves to the side of the pressure chamber with the lower pressure, the first rotating body and the second rotating body. It rotates relative to the body. Due to this relative rotation, a phase difference occurs between the rotation phase of the first rotating body and the rotation phase of the second rotating body.

Therefore, the rotational phase of the drive shaft and one of the first rotary body and the second rotary body is the same as that of the first rotary body and the second rotary 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,
It 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 the phase difference.

When the internal combustion engine is started, the relative rotation restricting means holds the vane at a position corresponding to the starting time of the internal combustion engine, which is located approximately in the middle of the recessed portion, and holds the vane relative to 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 regulating means releases the regulation of the relative rotation of both the rotating bodies after a predetermined time has elapsed from the start of the internal combustion engine. That is, the vane held at the start-up corresponding position located substantially in the middle of the recess can be moved from that position. Therefore, by moving the vanes according to the pressure in both pressure chambers and relatively rotating both rotating bodies,
The valve timing can be changed from the valve timing suitable for starting the engine to both the advance side and the retard side.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the invention embodying a variable valve timing (VVT) mechanism of an internal combustion engine according to the present invention will be described below with reference to the drawings.

The engine 70 shown in FIG. 1 comprises an intake side camshaft 15 as a driven shaft, an exhaust side camshaft 71 and a crankshaft 72 as a drive shaft, and these shafts 15, 71, 72 are sprockets 11, 7 respectively.
They are connected by 3, 74 and a chain 75. Two
One idler 76 gives tension to the chain 75. The VVT mechanism 10 in this embodiment is provided on the intake side camshaft 15. Then, as the crankshaft 72 rotates, both camshafts 15, 71 are rotated in synchronization with the crankshaft 72 via the chain 75 and the sprockets 11, 73, 74, and the intake valve 77 and the exhaust valve 78 are predetermined. It is opened and closed with the valve timing of.

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

The intake camshaft 15 is provided with 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 cam shaft 15 has a cylinder head 79 and a bearing cap 80 between the flanges 151a and 151b.
It is rotatably supported by.

The rear plate 14 has a disc portion 141 and a boss 142, and a recess 141 formed in the disc portion 141.
It is fitted to the front flange 151a at a. The engagement pin 31 projects forward from the flange 151 a of the camshaft 15 and is engaged with the pin hole 147 of the disc portion 141. Therefore, the rear plate 14 rotates integrally with the cam shaft 15.

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

The sprocket 11 has a substantially cylindrical shape, and is arranged around the disk portion 141 of the rear plate 14 and the outer circumference of the rotor 12. The sprocket 11 is the disc portion 14
1 has a recess 116 having a shape corresponding to the outer diameter of the recess 1.
It is supported by 16 so as to be relatively rotatable along the outer periphery of the disk portion 141. Incidentally, the sprocket 1 according to the present 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 rotatably mounted on the outer circumference 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 a bolt 32. Therefore,
The front cover 13, the rotor 12, the rear plate 14, and the cam shaft 15 can rotate integrally.

A plurality of teeth 112 are formed on the outer circumference of the sprocket 11 so as to correspond to the recesses 116 of the sprocket 12, and the chain 75 is formed on the outer circumference of the teeth 112.
Is hung. On the inner circumference of the sprocket 12, four protrusions 115 projecting toward the center are formed at equal angular intervals. Between the protrusions 115, four recesses 114 for accommodating the vanes 122 of the rotor 12 and a space for accommodating the cylindrical portion of the rotor 12 are formed. Then, in a state where each vane 122 is arranged in each recess 114, an advance chamber 101 and a retard chamber 102 are formed on both sides of each vane 122.

The seal member 1 is provided on the outer end surface of each vane 122.
23 is attached and pressed against the inner wall surface of each recess 114 by the leaf spring 124. Therefore, each seal member 123
Thus, the advance chamber 101 and the retard chamber 102 are sealed. When oil is supplied into both chambers 101 and 102, the pressure of the oil connects rotor 12 and sprocket 11, and the rotation of sprocket 11 is transmitted to rotor 12 via the oil.
The camshaft 15 is rotated together with 2.

The pressure in the retard chamber 102 becomes larger than the pressure in the advance chamber 101, and 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 arranged at the most retarded position with respect to the crankshaft. On the contrary, 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 15, the camshaft 15 is arranged at the most advanced position with respect to the crankshaft 72.

As shown in FIGS. 2-4, the sprocket 11
A stepped accommodating hole 117 extending parallel to the axis of the camshaft 15 is formed in one of the convex portions 115. The rear plate 1 is provided so as to face the accommodation hole 117.
A lock recess 145 is formed in the disk portion 141 of No. 4. The lock recess 145 has an elliptical shape along the radial direction.

The housing hole 117 has a large diameter portion 117a and a small diameter portion 1a.
17b and. The lock pin 20 includes a large diameter portion 22 located at the front and a small diameter portion 21 located at the rear, and is slidably inserted into the stepped hole 117. The large diameter portion 22 of the lock pin 20 corresponds to the large diameter portion 117 a of the accommodation hole 117.
The smaller diameter portion 21 of the lock pin 20 is set longer than the smaller diameter portion 117b of the accommodation 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 accommodation hole 117.

The pressure of the oil supplied to the pressure chamber 181 acts on the stepped portion 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 constitutes the second pressure receiving surface 26. Also, 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 to engage with the lock recess 145. Therefore, the urging force acting on each pressure receiving surface 25, 26 by the oil pressure causes the spring 24
If it is smaller than the urging force of the
4 or the locking recess 145.

When relative rotation occurs between the sprocket 11 and the rear plate 14 while the lock pin 20 is engaged with the front surface of the disc portion 141, when the lock pin 20 faces the lock recess 145, It engages with the lock recess 145. At this time, the sprocket 11 is the rear plate 1
4 mechanically connected.

Further, the lock pin 20 is locked by the lock recess 145.
, 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 the predetermined angle α toward the advance side.

Contrary to the above case, when the urging force acting on each pressure receiving surface 25, 26 by the oil pressure is larger than the urging force of the spring 24, the lock pin 20 is separated from the front surface of the disc portion 14, and the sprocket is sprocketed. 11 and rear plate 14
Relative rotation between and is permitted. At this time, since the lock pin 20 is immersed in the accommodation hole 117, the disk portion 14
Will not wear due to contact with.

Next, the 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, an annular advance groove 81 is formed on the inner peripheral surfaces of the cylinder head 79 and the bearing cap 80 on the outer periphery of the journal 151.
Is the passage 82 and the oil control valve (OCV) 4
It is connected to the hydraulic pump 46 via 0. The hydraulic pump 46 is a mechanical pump driven by rotation of the crankshaft 72.

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

On the other hand, in order to communicate with each retard chamber 102,
On the rear surface of the rotor 12, a cross-shaped retarded passage 126 having substantially the same shape as the advanced passage 125 is formed (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 forms the passage 83.
, And the OCV 40 to the hydraulic pump 46.

Further, inside the journal 151, a linear connecting passage 15 extending parallel to the axis of the camshaft 15 is provided.
6 are formed, and the connecting passages 15 are formed in the rear plate 14.
6 and the retard passage 126, an intermediate passage 84 is formed. Therefore, the 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 accommodation hole 117 is connected to the retard chamber 102 by a retard connecting passage 119 formed in 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.
A portion of the lock pin 20 that is located on the rear side of the inside of 7 has a lead angle connecting path 1 formed on the rear surface of the protrusion 115.
18 is connected 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.

Further, 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 space 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 chamber 101, 102. OCV
40 includes a casing 45, and the spool 44 is accommodated in the casing 45 so as to be capable of reciprocating. The electromagnetic actuator 41 includes a plunger 43, and the plunger 43 is in contact with the spool 44. The coil spring 42 in the casing 45 connects the spool 44 to the plunger 4
It is biased to the 3rd 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 the oil pan 47 via the 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.
It is connected to the retard groove 157 via. The reservoir port 45r communicates with the oil pan 47.

The spool 44 is a cylindrical valve element, which moves under the duty control of the actuator 41 against or against the urging force of the spring 42. The spool 44 includes a plurality of lands 44a, and with the movement thereof,
Two ports (45a, 4
5t), (45a, 45r), (45b, 45t),
The oil flow between (45b, 45r) is shut off. The spool 44 has a plurality of passages 44b and 44c between the lands 44a.
b and 44c are the two ports (45a, 45t), (45a, 45r), (4) as the spool 44 moves.
5b, 45t) and (45b, 45r) are allowed to flow.

When the engine is stopped, the hydraulic pump 46, O
Both CVs 40 are kept stopped. Therefore,
No oil is supplied to the advance chamber 101 and the retard chamber 102, and no hydraulic pressure is applied to the lock pin 20.
Further, sufficient hydraulic pressure is not generated even when the engine 70 is started, that is, during cranking. As a result, the lock pin 20 causes the lock recess 145 of the rear plate 14 or the rear plate 14 to move due to the biasing force of the spring 24.
Is engaged with the front surface of.

When the sprocket 11 is rotated along with the 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 cam shaft 15 are mechanically connected.
Therefore, when the engine 70 is started, the sprocket 1
Therefore, the rotation 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 camshaft 15 is mechanically determined. Then, the phase is shifted toward the advance side by a predetermined angle α from the phase that realizes the most retarded valve timing, and is set to a phase that can realize the optimum valve timing for engine start.

On the other hand, when the hydraulic pump 46 generates a sufficient hydraulic pressure after the engine 70 is started and the spool 44 is moved to the left in FIG. 4 by the actuator 41, the passage 44b moves to the tank port 45t. To communicate with the A port 45a (hereinafter, the position of the spool 44 will be referred to as an "advance 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 connected to the connection passage 155 in the journal 151,
The oil pressure is supplied to the advance chamber 101 through the gap 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. And 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 radiated through the radiation passage 144 to the lock pin 2.
0 acting on the second pressure receiving surface 26. In addition, 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 advance room 1
When the amount of oil supplied to 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 separated from the lock recess 145 and stored in the accommodation hole 117. 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 rotational 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 in which the intake valve 77 and the exhaust valve 78 are simultaneously opened is expanded. It

On the other hand, when the spool 44 is moved to the right in FIG. 4 by the actuator 41 after the engine is started, the passage 44b will move to the tank port 45t and the B port 4b.
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 through 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 is transferred to the advance passage 125 of the rotor 12, the gap 143, and the connection passage 1 in the journal 151.
55, the advance groove 81 and the passage 82, and the OCV 40A
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 via the connection passage 119 shown in FIG.
Acting on the first pressure receiving surface 25 of. When the urging force due to the pressure of the oil exceeds the urging force of the spring 24,
The lock pin 20 is separated from the lock recess 145 and stored in the accommodation hole 117. Therefore, smooth relative rotation between the rotor 12 and the sprocket 11 is allowed.

After that, the pressure in the retard chamber 102 increases,
And 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 camshaft 15 is delayed, and the valve overlap period is reduced or eliminated.

Since the lock recess 145 of this embodiment has an elliptical shape along the radial direction, when the rotor 12 and the rear plate 14 are rotated toward the retard side, the lock recess 145 is moved into the retard chamber. It does not communicate with 102. Rotor 1
When the rear plate 2 and the rear plate 1 rotate toward the advance side, the lock recess 145 communicates with the advance chamber 101. However, since the lock recess 145 communicates with the advance chamber 101 via the gap 143 and the radiation passage 144, the flow of oil is not hindered.

Further, after the engine is started, the OCV 40 moves the spool 44 to the approximately intermediate position between the "advance position" and the "retard position", and the A port 45
The a and B ports 45b are both closed by the land 44a (hereinafter, the position of the spool 44 at this time is referred to as a "holding position"). Therefore, the oil is supplied to the advance chamber 101 and the retard chamber 102, and both chambers 101, 10
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 this embodiment,
The target phase angle of the camshaft 15 calculated based on the operating 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 deviation of both phase angles. The intake valve 1 can be adjusted by appropriately adjusting the “angular position”, the “retard position”, and the “holding position”.
The valve timing of 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 as the valve timing is changed.

Further, in the present embodiment, as shown in FIG. 6 (b), when the engine is started, the sprocket 11 is in a phase separated by a predetermined angle α from the phase that realizes the most retarded valve timing. And the camshaft 15 are locked. Therefore, unlike the conventional variable valve timing mechanism (see FIG. 6A) in which the engine 70 is started at the most retarded position, the valve timing during engine operation is further retarded from the valve timing at engine startup. Can be changed to.

When the engine 70 is stopped, the hydraulic pump 46 is stopped and the oil supply to the engine 70 is stopped. Further, the spool 44 of the OCV 40 is stopped by the biasing force of the spring 42 at a position where the port 45b and the port 45t shown in FIG. 4 are communicated with each other, that is, an oil supply position to the retard chamber 102. At this time, the pump 46 is stopped, so that 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 ports 45a and 45r.

When the oil flows back, 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, based on the reaction force from the intake valve 77, the camshaft 15 and the rear plate 14 together with the rotor
2 rotates on the retard side, that is, counterclockwise in FIG. When the lock recess 145 faces the lock pin 20 due to the rotation, the lock pin 20 engages with the lock recess 145. As a result, relative rotation between the rotor 12 and the sprocket 11 is restricted. When the two 145 and 20 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 is in the phase separated by the predetermined angle α from the phase that realizes the valve timing with the most retarded angle. 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, good starting characteristics of the engine 70 can be ensured.

Further, in this embodiment, the lock pin 20 is engaged in the lock recess 145 to restrict the relative rotation between the sprocket 11 and the rear plate 14. The relative rotation of 14 can be regulated more reliably, and the lock pin 2
By moving 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, the valve timing can be changed to the retard side further than the phase for starting the engine during the operation of the engine 70. for that reason,
A desired intake inertia effect can be obtained in a high rotation range of the engine 70 to improve output characteristics. Furthermore, since the valve timing with the most retarded angle is not restricted by the valve timing at the time of engine start, it is possible to reduce pumping loss, and as a result, it is possible to improve fuel efficiency characteristics.

Further, in this embodiment, the hydraulic pressure can be constantly applied to the lock pin 20 during the valve timing changing period in which the rotor 12 and the sprocket 11 are kept relatively rotatable. Therefore, the lock pin 20 is held in the receiving hole 1 during the valve timing changing period.
Since the lock pin 20 and the rear plate 14 do not protrude from each other, wear of the lock pin 20 and the rear plate 14 can be prevented.

Further, in the present embodiment, the pressure chamber 181, the lock recess 145, and the rear end side inside of the accommodation hole 117 are communicated with the advance chamber 101 or the retard chamber 102 to supply the oil, and the oil is supplied. The position of the lock pin 20 is changed by the pressure and the biasing force of the spring 24. Therefore, for example, the number of parts can be reduced and the configuration can be simplified as compared with a configuration in which the position of the lock pin 20 is changed by an actuator such as an electromagnetic solenoid.

Further, according to this embodiment, the advance chamber 101
And 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 chamber 101, 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 inevitably small. Therefore, when the oil pressure is not sufficient as described above, the lock pin 20 is always engaged with the lock concave portion 145 by the urging force of the spring 24, so that the rotor 12 vibrates in the concave portion 114. It is possible to prevent the problem that an abnormal noise is generated due to collision with the inner peripheral wall of the portion 114.

The above embodiment can be implemented by changing the configuration as shown 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 side 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 mechanism. Further, a VVT mechanism may be provided on both the intake camshaft 15 and the exhaust camshaft 71 to change the valve timings of the intake valve and the exhaust valve.

In the above embodiment, the shafts 15 and 7
1, 1 and 72 are drive-coupled by the sprockets 11, 73 and 74 and the chain 175, but they may be drive-coupled by a timing belt or a gear.

In the above embodiment, the intake camshaft 15, the exhaust camshaft 71, the crankshaft 72
Chain 175 against each shaft 15,7
1, 72 are connected to be driven. On the other hand, in the VVT mechanism 10, the sprocket 11 is changed to a drive gear having a plurality of teeth on its outer circumference. Then, this VVT mechanism is provided at one end of the exhaust side camshaft.
On the other hand, a sprocket is provided on the other end of the exhaust side camshaft. Then, a chain is hooked on the sprocket and the sprocket of the crankshaft to drively connect the exhaust side camshaft and the crankshaft. Further, a driven gear is provided at one end of the intake side cam shaft, and the driven gear is meshed with the drive gear of the exhaust side cam shaft. According to such a configuration, the V provided on the exhaust side camshaft
The VT mechanism can change the rotation phase of the intake camshaft to change the valve timing of the intake valve. In this configuration, the exhaust side cam shaft corresponds to the drive shaft of the present invention, and the intake side cam shaft corresponds to the driven shaft. In the above embodiment, the sprocket 11 is provided with the accommodation hole 117 for accommodating the lock pin 20, and the rear plate 14 is provided with the lock recess 145 with which the lock pin 20 is engaged. On the other hand, the accommodation hole for the lock pin may be provided in the rear plate that rotates 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 restricted 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 that is pressed against the front surface of the disk portion 141, and the relative rotation between the sprocket 11 and the rear plate 14 is restricted by the frictional force generated by the pressing. Good.

The technical idea understood from the above embodiment will be described below along with its effects. (A) In the variable valve timing mechanism for an internal combustion engine according to claim 1, the relative rotation restricting means is the first
An engaging recess formed in one of the rotating body and the second rotating body, and movably supported by the other of the first rotating body and the second rotating body. A removable pin, which engages with the engagement recess at the time of starting the internal combustion engine, and disengages from the engagement recess after a predetermined time has elapsed from the start of the internal combustion engine. Is characterized by.

According to this structure, the relative rotation of the two rotating bodies can be more reliably restricted by the engagement of the pin and the engaging 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 according to (a) above, the relative rotation restricting means is a biasing means that constantly biases the pin in a direction to engage with the engagement recess. A pressure that causes the pin to disengage from the engagement recess by applying a pressure equal to the pressure supplied to at least one of the first pressure chamber and the second pressure chamber to the pressure receiving surface formed on the pin. Means are further provided.

According to this structure, the engagement / disengagement state of the pin and the engaging 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 relative rotation of the first rotary body and the second rotary body cannot be controlled by the pressure,
The pin can be engaged with the engagement concave portion to restrict the relative rotation of both rotating bodies, and it is possible to suppress the relative rotation of both rotating bodies in an uncontrollable state.

[0084]

According to the present invention, by the relative rotation restricting means,
At the time of starting the internal combustion engine, the vane is held at a position corresponding to the starting time of the internal combustion engine, which is located substantially in the middle of the recessed portion, to restrict the relative rotation of 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 passed from the time.

Therefore, at the time of starting the internal combustion engine, 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 rotate relative to each other, and the valve timing is the valve timing suitable for the engine starting. Can be further changed to both the retard side and the advance side. As a result, according to the present invention, it is possible to secure the startability of the internal combustion engine and expand the variable region of the valve timing.

[Brief description of drawings]

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

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

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

FIG. 4 is a cross-sectional view taken along line 4-4 of FIG.

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

FIG. 6 is an explanatory diagram showing an operating 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 ... Intake side camshaft, 20
… Lock pin, 24… Spring, 70… Engine, 7
2 ... Crank shaft, 77 ... Intake valve, 101 ... Advance chamber, 102 ... Retard chamber, 114 ... Recess, 122 ... Vane, 145 ... Lock recess.

Claims (1)

[Claims] 1. A first rotating body having at least one recess therein, a plurality of vanes partitioning the recess into a first pressure chamber and a second pressure chamber, and the first rotation enabling relative rotation. A second rotating body that is combined with a body, a drive shaft that synchronously rotates one of the first rotating body and the second rotating body at a reference rotation phase of the internal combustion engine, and the first rotating body or the second rotating body A driven shaft that is interlocked with the other of the two, and a valve that is selectively driven by the driven shaft to a valve opening position or a valve closing position, and a pressure applied to the first pressure chamber and the second pressure chamber. Of the valve driven by the driven shaft by rotating the first rotating body and the second rotating body relative to each other and changing the rotational phase of the driven shaft with respect to the reference rotational phase of the internal combustion engine. Change the valve timing In a further variable valve timing mechanism for an internal combustion engine, at the time of starting the internal combustion engine, the vane is held at a position corresponding to the starting time of the internal combustion engine located substantially in the middle of the recess to hold the vane and the first rotating body. A variable valve for an internal combustion engine, further comprising relative rotation restricting means for restricting relative rotation with respect to the two-rotation body and for canceling the restriction after a predetermined time has elapsed from the start of the internal combustion engine. Timing mechanism.