JP2000018056A - Variable valve train for internal combustion engines - Google Patents

Abstract

(57) [Object] To provide a variable valve actuation device for an internal combustion engine, which can prevent the output torque of the internal combustion engine from dropping when the target value of the valve timing is largely changed by changing the valve lift amount. I do. A valve timing of an intake valve in an engine is adjusted by bringing an actual advance amount of the valve timing closer to a target advance amount calculated based on an operation state of the engine. And
When the valve lift amount of the intake valve 19 is changed, the target advance amount greatly changes. When the valve lift amount is changed, the response speed of the actual advance amount change with respect to the change of the target advance amount is increased. Therefore, the actual advance amount follows the change in the target advance amount when the valve lift amount is changed with good responsiveness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve apparatus for varying the valve lift and valve timing of an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, in an internal combustion engine such as a vehicle-mounted engine, the opening and closing characteristics of an intake valve and an exhaust valve are appropriately changed in order to improve output and reduce emission. As a device for changing the valve characteristics in this way, for example, a valve operating device described in Japanese Patent Publication No. 5-43847 is known.

This device includes a variable valve lift mechanism for varying the valve lift of the internal combustion engine and a variable valve timing mechanism for varying the valve timing of the engine. The variable valve lift mechanism switches the valve lift of the internal combustion engine between low speed and high speed in accordance with the operating state of the engine. Further, the variable valve timing mechanism brings the valve timing of the internal combustion engine closer to a target value set based on the engine operating state with a predetermined response speed.

The variable valve lift mechanism and the variable valve timing mechanism change the valve lift in accordance with the engine operating condition and bring the valve timing closer to a target value set in accordance with the engine operating condition. Thus, the output of the internal combustion engine can be improved and the emission can be reduced.

[0005]

By the way, when the valve lift is changed by the above-described variable valve lift mechanism, the amount of intake air changes greatly based on the change, and the operating state of the internal combustion engine changes greatly. Also, a large change occurs in the target value of the valve timing set based on the engine operating state.

However, when the target value of the valve timing greatly changes as described above, it takes a long time from the change of the target value to the actual valve timing reaching the target value. Until the valve timing reaches the target value, the actual valve timing deviates from the target value and becomes inappropriate for the engine operating state.

Therefore, as described above, it takes a long time for the actual valve timing to reach the target value, so that the period during which the actual valve timing deviates from the target value becomes longer, and the output of the internal combustion engine is increased during the same period. The torque will drop.

The present invention has been made in view of such circumstances, and an object of the present invention is to reduce the output torque of the internal combustion engine when the valve lift is changed and the target value of the valve timing is largely changed. It is an object of the present invention to provide a variable valve operating device for an internal combustion engine that can prevent the occurrence of the internal combustion engine.

[0009]

According to a first aspect of the present invention, there is provided a variable valve apparatus for an internal combustion engine, wherein the valve lift and valve timing of the internal combustion engine are variable. Valve timing variable means for approaching a target value set according to the engine operating state with a predetermined response speed, and a response speed of the valve timing when the valve lift amount is changed is the same response speed when the valve lift amount is not changed Response speed control means for controlling the valve timing variable means so as to be larger than the above.

According to this configuration, when the valve lift amount is changed, the target value set in accordance with the engine operating state changes greatly. However, the response speed of the valve timing approaching the target value changes when there is no valve lift amount. Since the valve timing is made larger than that at the time of the change, the actual valve timing is quickly brought closer to the target value after the change. Therefore, even if the valve timing target value greatly changes, the period during which the target value deviates from the actual valve timing is shortened, and it is possible to prevent the output torque of the internal combustion engine from dropping during the same period. .

According to a second aspect of the present invention, in the first aspect of the present invention, the response speed control means is provided for a period from when the valve lift is changed to when the valve timing first reaches the target value. However, the response speed of the valve timing is increased.

When the response speed of the valve timing approaching the target value is increased, the valve timing can quickly approach the target value, but it takes time to converge the valve timing to the target value. become. However, according to this configuration, since the response speed of the valve timing is increased only until the valve timing reaches the target value for the first time after the valve lift is changed, the valve timing is quickly changed when the valve lift is changed. The target value is approached and quickly converges to the target value.

According to the third aspect of the present invention, the first or second aspect is provided.
In the described invention, the valve timing variable means is driven in accordance with a control amount obtained based on the target value and the actual valve timing, and the response speed control means changes the valve timing by changing the control amount. The response speed was increased.

According to this structure, the response speed of the valve timing can be accurately increased by changing the control amount for driving the variable valve timing means. A drop in output torque is suitably prevented.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment in which the present invention is applied to an automobile engine will be described below with reference to FIGS.

As shown in FIG. 1, a piston 12 is provided in a cylinder block 11a of the engine 11 so as to be able to reciprocate. This piston 12 is connected to a connecting rod 13
Through a crankshaft 14 which is an output shaft of the engine 11. The reciprocating movement of the piston 12 is converted into rotation of the crankshaft 14 by the connecting rod 13.

A signal rotor 14a is mounted on the crankshaft 14. A plurality of protrusions 14b are provided on the outer periphery of the signal rotor 14a at equal angles around the axis of the crankshaft 14. A crank sensor 14c is provided on the side of the signal rotor 14a. Then, the crankshaft 14 rotates, and each protrusion 1 of the signal rotor 14a is rotated.
4b sequentially passes by the side of the crank sensor 14c, so that the sensor 14c outputs a pulse-like detection signal corresponding to the passage of each of the projections 14b.

A cylinder head 15 is provided at the upper end of the cylinder block 11a, and a combustion chamber 16 is provided between the cylinder head 15 and the piston 12.
An intake port 17 and an exhaust port 18 provided on the cylinder head 15 communicate with the combustion chamber 16. Further, the intake port 17 and the exhaust port 18 are provided with an intake valve 19 and an exhaust valve 20, respectively.

An intake camshaft 21 and an exhaust camshaft 22 for opening and closing the intake valve 19 and the exhaust valve 20 are rotatably supported on the cylinder head 15. These intake and exhaust camshafts 21,
To 22, the rotation of the crankshaft 14 is transmitted via a timing belt 23. Then, when the intake camshaft 21 rotates, the intake valve 19 is driven to open and close, and the intake port 17 and the combustion chamber 16 are communicated and shut off. When the exhaust camshaft 22 rotates, the exhaust valve 20 is opened and closed to drive the exhaust port 18 and the combustion chamber 1.
6 is communicated / blocked.

In the cylinder head 15, a cam sensor 22b for detecting a protrusion 22a provided on the outer peripheral surface of the intake camshaft 21 and outputting a detection signal is provided on a side of the intake camshaft 21. Then, when the intake camshaft 21 rotates, the protrusion 22a of the shaft 21 passes by the side of the cam sensor 22b. In this state, a detection signal is output from the cam sensor 22b at predetermined intervals corresponding to the passage of the protrusions 22a.

An intake pipe 30 is connected to the intake port 17. The intake port 17 and the interior of the intake pipe 30 form an intake passage 32. An exhaust pipe 31 is connected to the exhaust port 18, and an exhaust passage 33 is provided between the intake port 17 and the exhaust pipe 31. The intake passage 32
A throttle valve 35 whose opening degree is adjusted based on the amount of depression of an accelerator pedal 34 provided in the cabin of the vehicle is provided in the upstream part of the vehicle. The amount of air drawn into the combustion chamber 16 is adjusted by adjusting the opening of the throttle valve 35. A vacuum sensor 36 that detects the pressure in the intake passage 32 and outputs a detection signal corresponding to the detected pressure is provided downstream of the throttle valve 35 in the intake pipe 30.

Further, at the downstream end of the intake pipe 30, a combustion chamber 1 is provided.
A fuel injection valve 37 for injecting fuel into the inside 6 is provided. The fuel injection valve 37 is connected to the intake passage 32.
When the air inside the combustion chamber 16 is drawn into the combustion chamber 16, the combustion chamber 1
The fuel is injected toward 6 to form a mixture comprising fuel and air. On the other hand, the combustion chamber 1
An ignition plug 38 for igniting the air-fuel mixture filled in the fuel cell 6 is provided. This spark plug 38
It is connected to a vehicle battery 40 via an igniter module 39 provided in the engine 11.

In such an engine 11, during the intake stroke, the combustion chamber 16
A negative pressure is generated in the internal combustion engine, and air is sucked into the combustion chamber 16 through the intake passage 32 by the negative pressure. Also, the fuel injection valve 3
From 7, an amount of fuel corresponding to the amount of air sucked into the combustion chamber 16 is injected toward the combustion chamber 16, and as a result, the combustion chamber 16 is filled with an air-fuel mixture. You.

Thereafter, in the compression stroke of the engine 11, the mixture in the combustion chamber 16 is compressed by the rise of the piston 12. The air-fuel mixture compressed in the combustion chamber 16 is ignited by the spark plug 38 and explodes, and the explosive force lowers the piston 12 to move the engine 11 to an explosion stroke. By this explosion stroke, the engine 11 obtains the driving force. The air-fuel mixture burned in the combustion chamber 16 is sent out to the exhaust passage 33 as exhaust gas by the rise of the piston 12 in the exhaust stroke of the engine 11.

Next, a variable valve apparatus for varying valve characteristics such as the valve lift and valve timing of the intake valve 19 will be described with reference to FIGS.
As shown in FIG. 2, the variable valve operating device includes a variable valve timing mechanism 24 provided at an end of the intake camshaft 21 and a variable valve lift mechanism provided between the intake camshaft 21 and the intake valve 19. 71.

The variable valve timing mechanism 24 has a pulley 24 a for transmitting the rotation of the crankshaft 14 from the timing belt 23 to the intake camshaft 21.
It has. The variable valve timing mechanism 24
Is driven by the hydraulically driven crankshaft 14.
, The rotational timing of the intake camshaft 21 is changed, and the valve timing of the intake valve 19 is adjusted.

The hydraulic drive of the variable valve timing mechanism 24 is performed by supplying and discharging oil in an oil pan 25 provided below the engine 11 to and from the variable valve timing mechanism 24. The supply and discharge of oil to and from the variable valve timing mechanism 24
Advance control oil passage 4 provided between oil pan 4 and oil pan 25
7, retard control oil passage 48, oil control valve (O
CV) 49, a supply passage 50, a discharge passage 51, and an oil pump 52.

Also, the valve lift variable mechanism 71
Are located corresponding to the high-speed cam 72a and the low-speed cam 72b provided on the intake camshaft 21 and having different cam profiles. The variable valve lift mechanism 71 includes a high-speed cam 72a and a low-speed cam 72 that are hydraulically driven to open and close the intake valve 19.
By switching between b and b, the valve lift of the intake valve 19 is changed. The cam profiles of the high-speed cam 72a and the low-speed cam 72b are the same as those of the high-speed cam 72.
a when the intake valve 19 is opened / closed by the low speed cam 72b.
Is formed so as to be larger than the valve lift amount when the valve is opened and closed.

The hydraulic drive of the variable valve lift mechanism 71 is performed by supplying and discharging the oil in the oil pan 25 to and from the variable valve lift mechanism 71. The supply and discharge of oil to and from the variable valve lift mechanism 71 are performed by a cam switching control oil passage 73 provided between the mechanism 71 and the oil pan 25, and an oil switching valve (O).
SV) 74, the supply passage 75, the discharge passage 76, and the oil pump 52.

Here, the variable valve timing mechanism 2
4 and an oil supply structure for driving the variable mechanism 24 will be described with reference to FIGS. FIG. 3 is a sectional view showing an oil supply structure for the variable valve timing mechanism 24, and FIG.
FIG. 4 is a cross-sectional view illustrating an internal structure of a fourth example. As shown in FIG.
The journal 21a of the intake camshaft 21 provided with the variable valve timing mechanism 24 is rotatably supported by a bearing 15a of the cylinder head 15.
The tip (left end in FIG. 3) of the intake camshaft 21 passes through the center of the pulley 24a. The pulley 24a is rotatable with respect to the intake camshaft 21. Further, a rotary member 41 is fixed to a distal end surface of the intake camshaft 21 by a bolt 42, and the rotary member 41 rotates integrally with the intake camshaft 21 about the axis L of the intake camshaft 21.

On the other hand, a housing 43 provided so as to cover the rotating member 41 is in contact with the tip side surface of the pulley 24a. The housing 43 includes a ring cover 44 provided so as to surround the outer periphery of the rotating member 41, and a closing plate 4 provided so as to close a distal end opening of the ring cover 44.
And 5. The pulley 24a, the ring cover 44, and the closing plate 45 are connected by bolts 46 so as to be integrally rotatable about the axis L of the intake camshaft 21.

The advance control oil passage 4 for supplying and discharging oil to and from the variable valve timing mechanism 24 is provided in the bearing portion 15a of the cylinder head 15 and the intake camshaft 21.
7 and a retard control oil passage 48 are provided. The advance control oil passage 47 and the retard control oil passage 48 extend to the inside of the variable valve timing mechanism 24, and are connected to the OCV 49 through the inside of the bearing 15a of the cylinder head 15. Further, a supply passage 50 and a discharge passage 51 are connected to the OCV 49. The supply passage 50 is connected to the oil pan 25 via an oil pump 52 driven by the rotation of the crankshaft 14, and the discharge passage 51 is directly connected to the oil pan 25.

The OCV 49 is a two-position, five-port electromagnetic switching valve, which is switched to select the A-side flow path by the biasing force of the coil spring 49b when the electromagnetic solenoid 49a is in a demagnetized state. When the electromagnetic solenoid 49a is excited, the OCV 49 is switched to select the B-side flow path.

When the OCV 49 is switched to select the A-side flow path, the supply passage 50 and the advance control oil passage 47 communicate with each other, and the discharge passage 51 and the retard control oil passage 48 communicate with each other. In such a state, the oil pump 5
2, the oil in the oil pan 25 is supplied to the supply passage 50,
The oil is supplied to the variable valve timing mechanism 24 via the OCV 49 and the advance control oil passage 47. The oil in the variable valve timing mechanism 24 is supplied to the retard control oil passage 4.
8. The oil is returned into the oil pan 25 via the OCV 49 and the discharge passage 51. In the variable valve timing mechanism 24 to which oil is supplied from the advance angle control oil passage 47, the intake camshaft 21 includes the crankshaft 14 (not shown in FIG. 3).
The drive timing of the intake valve 19 is advanced by changing the relative rotational phase between the pulley 24a and the intake camshaft 21 so as to advance the drive timing.

When the OCV 49 is switched to select the B-side flow path, the supply passage 50 and the retard control oil passage 4
8, and the discharge passage 51 and the advance control oil passage 47 communicate with each other. In such a state, the oil in the oil pan 25 is supplied to the variable valve timing mechanism 2 through the supply passage 50, the OCV 49, and the retard control oil passage 48.
4. The variable valve timing mechanism 24
The oil inside the oil pan 25 is returned to the oil pan 25 via the advance control oil passage 47, the OCV 49, and the discharge passage 51. The variable valve timing mechanism 24 supplied with oil from the retard control oil passage 48 operates the pulley 24 a so that the intake camshaft 21 is retarded with respect to the crankshaft 14.
And the relative rotation phase between the intake camshaft 21 and
The drive timing of the intake valve 19 is delayed.

Next, the detailed structure of the rotating member 41 and the housing 43 in the variable valve timing mechanism 24 is shown in FIG.
This will be described with reference to FIG. As shown in FIG.
3, four projecting portions 66 projecting toward the axis L of the intake camshaft 21 (FIG. 3) are formed at equal intervals in the circumferential direction of the housing 43 on the inner peripheral surface 44a of the ring cover 44. . Grooves 67 are formed at regular intervals in the circumferential direction of the housing 43 between the overhangs 66. Further, on the outer peripheral surface of the rotating member 41, each groove 67
Four vanes 68 projecting outwardly to be inserted into
Are provided at equal intervals in the circumferential direction of the rotating member 41.
The inside of each groove 67 into which each vane 68 is inserted is partitioned into an advance side hydraulic chamber 69 and a retard side hydraulic chamber 70 by the vane 68. The advance side hydraulic chamber 69 and the retard side hydraulic chamber 70 are located so as to sandwich the vane 68 from both sides in the circumferential direction of the rotating member 41. And, the advance side hydraulic chamber 69
The advance control oil passage 47 and the retard control oil passage 48 communicate with the retard hydraulic pressure chamber 70, respectively.

In the variable valve timing mechanism 24, when the electromagnetic solenoid 49a of the OCV 49 is demagnetized, oil is supplied from the advance control oil passage 47 to the advance hydraulic chamber 69, and the retard hydraulic oil Oil is discharged from the chamber 70 via the retard control oil passage 48. as a result,
The relative movement of each vane 68 in the direction of arrow A causes the rotation member 41 to relatively rotate rightward in the figure, and changes the relative rotation phase of the intake camshaft 21 with respect to the pulley 24a. In the variable valve timing mechanism 24, both the pulley 24a (housing 43) and the intake camshaft 21 rotate rightward in the figure based on the rotation of the crankshaft 14 transmitted via the timing belt 23. I do. Therefore, in this case, the intake camshaft 21 advances with respect to the crankshaft 14, and as a result, the valve timing of the intake valve 19 also advances.

Further, the electromagnetic solenoid 49a of the OCV 49
Is excited, the retard control oil passage 48 moves to the retard side hydraulic chamber 7.
The oil is supplied to the oil chamber 0 and the oil is discharged from the advance hydraulic chamber 69 via the advance control oil passage 47. As a result, as each vane 68 relatively moves in the direction opposite to the arrow A, the rotating member 41 relatively rotates in the same left direction, and the relative rotation phase of the intake camshaft 21 with respect to the pulley 24a changes in the opposite direction. Is done. In the variable valve timing mechanism 24, in this case, the intake camshaft 21
Is retarded with respect to the crankshaft 14, and as a result, the valve timing of the intake valve 19 is also retarded.

Next, the valve lift variable mechanism 71,
An oil supply structure for driving the variable mechanism 71 will be described with reference to FIGS. FIG. 5 is a perspective view showing the entire valve lift variable mechanism 71,
6 and 7 are enlarged sectional views showing the internal structure of the variable valve lift mechanism 71.

As shown in FIG. 5, the variable valve lift mechanism 71 includes a rocker arm body 78 rotatably mounted on a rocker shaft 77 parallel to the intake camshaft 21 (not shown in FIG. 5). ing. The rocker arm main body 78 is provided with a pressing contact portion 79 that contacts the upper end of the intake valve 19. A roller 80 is rotatably supported by the rocker arm body 78, and a low-speed cam 72b (FIG. 2) abuts the roller 80. Therefore, when the intake camshaft 21 rotates, the low-speed cam 7
2b pushes the intake valve 19 via the roller 80 and the rocker arm main body 78, and the intake valve 19 is driven to open and close.

In the rocker arm body 78, the roller 8
A cam follower 81 is provided next to 0. The cam follower 81 is supported so as to be able to reciprocate in a direction (up and down direction in the drawing) with respect to the rocker arm main body 78 and is urged upward by a coil spring 82. The head of the cam follower 81 is provided with a pressed portion 81a with which the high-speed cam 72a contacts. The cam follower 81 is fixed in the direction of immersion into the rocker arm main body 78 based on the oil pressure of the oil supplied to the cam switching control oil passage 73 formed inside the rocker shaft 77, or the lock is released. It will be.

An OSV 74 is provided in the cam switching control oil passage 73.
The supply path 75 and the discharge path 76 are connected to the OSV 74. The supply passage 75 is connected to the oil pan 25 via the oil pump 52, and the discharge passage 76 is directly connected to the oil pan 25. The OSV 74 is a 2-position 3-port type electromagnetic switching valve,
In the demagnetized state of the electromagnetic solenoid 74a, switching is performed so as to select the A-side flow path by the urging force of the coil spring 74b. When the electromagnetic solenoid 74a is excited, the OSV 74 is switched to select the B-side flow path.

When the OSV 74 is switched to select the A-side flow path, the supply passage 75 and the cam switching control oil passage 73
The oil in the oil pan 25 is supplied to the cam switching control oil passage 73 through the supply passage 75 and the OSV 74 by the oil pump 52. Thus, the cam follower 81 is fixed in the direction of immersion into the rocker arm body 78 based on the oil pressure of the oil supplied to the cam switching control oil passage 73. In this state, the rotation of the intake camshaft 21 causes the high-speed cam 72a to push the intake valve 19 via the cam follower 81 and the rocker arm main body 78, and the intake valve 19 is opened and closed.

When the OSV 74 is switched so as to select the B-side flow path, the cam switching control oil passage 73 and the retard control oil passage 48 communicate with each other, and the oil in the cam switching control oil passage 73 becomes the OSV 74 and the oil in the cam switching control oil passage 73. Oil pan 2 through discharge passage 76
Returned to 5. In this way, by discharging the oil from the cam switching control oil passage 73, the fixing of the cam follower 81 in the direction of immersion into the rocker arm main body 78 is released. In this state, when the cam follower 81 is pressed by the high-speed cam 72a, the cam follower 81 is immersed in the rocker arm main body 78, so that the intake valve 19 is opened and closed by the low-speed cam 72b.

Next, a structure for fixing the cam follower 81 in the direction of immersion in the rocker arm body 78 and a structure for releasing the fixation will be described with reference to FIGS. 6 and 7 are enlarged cross-sectional views of a portion of the rocker arm main body 78 where the cam follower 81 is provided.

As shown in FIG. 6, the rocker arm main body 78
Has a guide cylinder 83 into which the cam follower 81 is inserted.
Are provided to extend in the vertical direction in the figure. Also,
The rocker arm main body 78 is provided with a sliding hole 84 that communicates with the lower end of the guide cylinder 83 and extends in a direction perpendicular to the guide cylinder 83. The inner part of the sliding hole 84 is
A communication passage 84a communicating with the cam switching control oil passage 73 (FIG. 5).
Is connected to. A fixing member 85 is provided on the communication passage 84 a side of the cam follower 81 in the sliding hole 84 so as to be able to reciprocate along the sliding hole 84. Further, between the fixed member 85 and the communication passage 84a in the sliding hole 84, the cam switching control oil passage 73 is connected to the communication passage 84a.
A hydraulic chamber 84b to which oil is supplied via a.

The fixing member 85 has, at one end (the right end in FIG. 6), a contact portion 85a with which the lower end surface of the cam follower 81 contacts, and a contact surface at the lower end of the cam follower 81 on the side of the communication passage 84a. A spring receiving member 86 is provided in contact therewith. In the fixing member 85, a guide hole 87 extending in the same direction as the sliding hole 84 is provided at a position corresponding to the spring receiving member 86. A coil spring 88 for urging the fixing member 85 toward the communication passage 84a is provided in the guide hole 87. Then, the fixing member 85
Reciprocates in the sliding hole 84 based on the oil pressure of the oil supplied to the hydraulic chamber 84b and the urging force of the coil spring 88.

Therefore, when oil is supplied from the cam switching control oil passage 73 (FIG. 5) into the hydraulic chamber 84b through the communication passage 84a, the oil pressure of the oil causes the fixing member 85 to apply the urging force of the coil spring 88. It moves to the position shown in FIG. In this state, the lower end surface of the cam follower 81 comes into contact with the contact portion 85 a of the fixing member 85, and the cam follower 81 is fixed in the direction of immersion in the rocker arm body 78. Therefore, in this case, the high-speed cam 72
The opening of the intake valve 19 is driven by a.

When the oil is discharged from the hydraulic chamber 84b through the communication passage 84a and the cam switching control oil passage 73, the urging force of the coil spring 88 causes the fixing member 8 to move.
5 moves to the position shown in FIG. In this state, the contact portion 85a of the fixing member 85 is displaced from the position corresponding to the lower end surface of the cam follower 81, and the cam follower 81 can be immersed in the rocker arm body 78. Therefore, in this case, the opening and closing drive of the intake valve 19 is performed by the high-speed cam 72.
This is performed by the low-speed cam 72b instead of a.

Next, an electrical configuration of the variable valve operating device according to the present embodiment will be described with reference to FIG. The variable valve gear includes an electronic control unit (hereinafter referred to as “ECU”) 92 for controlling valve characteristics such as the valve timing and valve lift of the intake valve 19. The ECU 92 includes a ROM 93, a CPU 94, a RAM 95,
And a theoretical operation circuit including a backup RAM 96 and the like.

The ROM 93 is a memory that stores various control programs and maps and the like that are referred to when the various control programs are executed.
The arithmetic processing is executed based on various control programs and maps stored in the OM 93. The RAM 95 is a CPU
94 is a memory for temporarily storing the calculation result at 94, data input from each sensor, and the like.
Reference numeral 6 denotes a nonvolatile memory for storing data to be stored when the engine 11 is stopped. And ROM93, CP
The U 94, the RAM 95, and the backup RAM 96 are connected to each other via a bus 97, and are also connected to an external input circuit 98 and an external output circuit 99.

The external input circuit 98 includes the crank sensor 14
c, the cam sensor 22b, the vacuum sensor 36, and the like are connected, and the OCV 49 and the OSV
74 and the like are connected.

The ECU 92 configured as described above determines the engine speed NE based on the detection signal from the crank sensor 14c, and determines whether the engine speed NE exceeds a predetermined value (6000 rpm in the present embodiment). ,
The valve lift is changed between a high-speed valve and a low-speed valve.

That is, the ECU 92 determines the engine speed NE.
Is smaller than 6000 rpm, the OSV 74 is switched so that the electromagnetic solenoid 74a of the OSV 74 (FIG. 5) is excited to select the B-side flow path, and the low-speed cam 72b is selected as the cam for driving the intake valve 19 to open and close. In this state, the valve lift of the intake valve 19 is reduced, so that the low-speed torque of the engine 11 is improved and the idling operation is stabilized. When the low-speed cam 72b is selected, the shaft torque of the crankshaft 14 (engine output torque) changes with a change in the engine speed NE as shown by a solid line LL1 in FIG. 9A.

The ECU 92 determines the engine speed NE.
Is higher than 6000 rpm, the OSV 74 is switched so that the electromagnetic solenoid 74a of the OSV 74 is demagnetized and the A-side flow path is selected, and the high-speed cam 72a is selected as a cam for driving the intake valve 19 to open and close. In this state, the valve lift of the intake valve 19 is increased, and the maximum output of the engine 11 is increased. When the high-speed cam 72a is selected, the shaft torque of the crankshaft 14 changes as shown by a solid line LH1 in FIG. 9A with respect to a change in the engine speed NE.

The engine speed NE (6000 rpm), which is a criterion for cam switching, is determined by the solid lines LL and LH.
Is the engine speed NE when the vehicle crosses. By using such an engine speed NE as a criterion for cam switching, both low-speed performance and high-speed performance of the engine 11 can be improved.

On the other hand, the ECU 92 is provided with the vacuum sensor 3
The intake air amount is obtained based on the detection signal from the engine 6, and the target advance amount Tvt of the valve timing of the intake valve 19 is calculated based on the intake air amount and the engine speed NE with reference to the map of FIG. Further, the ECU 92 obtains the actual advance amount Rvt of the valve timing of the intake valve 19 based on the detection signals from the crank sensor 14c and the cam sensor 22b.

When the target advance amount Tvt is calculated as described above, the ECU 92 adjusts the valve timing of the intake valve 19 by duty controlling the voltage applied to the electromagnetic solenoid 49a of the OCV 49 (FIG. 3). The actual advance angle Rvt is made to coincide with the target advance angle Tvt. By adjusting the valve timing of the intake valve 19 in this manner, a high output torque can be obtained in the entire operation range of the engine 11.

As is apparent from the map shown in FIG. 16, when the low-speed cam 72b is selected as the cam for driving the intake valve 19 to open and close, and when the high-speed cam 72a is selected, the intake air amount is different. The transition tendency of the target advance amount Tvt based on the change of the engine speed NE differs. Therefore, when the cam that drives the opening and closing of the intake valve 19 is switched due to the engine speed NE exceeding 6000 rpm, the target advance angle amount Tvt for which the map calculation is performed is greatly changed. Here, the cam switching mode when the engine speed NE changes and exceeds 6000 rpm, and the target advance amount Tvt and the actual advance amount Rv of the valve timing of the intake valve 19 are described.
The transition of t is shown in FIGS.

FIG. 12 shows that the engine speed NE increases to 6
6 is a time chart showing a cam switching mode when the rotation speed exceeds 000 rpm, and changes in a target advance angle Tvt and an actual advance angle Rvt. As can be seen from this time chart, as shown in FIG.
When the cam for opening and closing the intake valve 19 is switched from the low-speed cam 72b to the high-speed cam 72a as shown in FIG. 12A, the target advance angle Tv
t greatly changes as shown in FIG. This is because, as indicated by the solid lines LL2 and LH2 in FIG. 9B, the transition tendency of the target advance angle Tvt with respect to the change in the engine speed NE is greatly different from 6000 rpm.

When the target advance angle Tvt greatly changes during cam switching as described above, the actual advance angle Rvt is reduced by the mechanical response delay in the operation of the variable valve timing mechanism 24. It takes a lot of time to match Tvt. That is, when changing the valve lift amount by switching the cam, the target advance angle amount Tvt
12C immediately changes greatly as shown by the solid line in FIG. 12C, whereas the actual advance amount Rvt gradually changes as shown by the broken line in FIG. Then, the actual advance amount R
Until vt reaches the target advance angle Tvt, the actual advance angle Rvt deviates from the target advance angle Tvt and becomes inappropriate for the operating state of the engine 11, and the shaft torque of the engine 11 May fall.

The drop in the engine output torque will be described with reference to the graph of FIG. This graph is
The change of the shaft torque with respect to the change of the valve timing advance amount Rvt under the condition that the engine speed NE is kept constant is shown by separate solid lines LL3 and LH for each of the cams 72a and 72b.
3.

The engine speed NE increases to 6000 r
pm, the actual advance angle Rvt becomes equal to the target advance angle T
Assuming that the shaft torque and the advance amount Rvt immediately change in response to a large change in vt, the shaft torque and the advance angle Rvt sequentially change from the state indicated by the point P1 to the state indicated by the points P2 and P3 as indicated by solid arrows in the figure. It will be. However, actually, the advance amount Rvt changes with a delay with respect to the change in the target advance amount Tvt, and the changes in the advance amounts Rvt and Tvt are shifted. As shown by the two-dot chain line arrow, the state sequentially changes from the state indicated by the point P1 to the state indicated by the points P4 and P3. Due to such a change from the state indicated by the point PI to the state indicated by the point P4, a drop occurs in the shaft torque of the engine 11 as indicated by a solid line X1 in FIG.

On the other hand, the engine speed NE decreases to 60
FIG. 14 is a time chart showing the cam switching mode when the rotation speed exceeds 00 rpm, and changes in the target advance angle Tvt and the actual advance angle Rvt. As can be seen from this time chart, the engine speed NE exceeds 6000 rpm as shown in FIG. 14 (b), and the cam for opening and closing the intake valve 19 is moved to the high speed cam 72a as shown in FIG. 14 (a).
When the cam is switched to the low-speed cam 72b, the target advance amount Tvt greatly changes as shown in FIG.

When the target advance angle Tvt greatly changes during the cam switching as described above, the actual advance angle Rvt is reduced by the mechanical response delay in the operation of the variable valve timing mechanism 24. It takes a lot of time to match Tvt. That is, when changing the valve lift amount by switching the cam, the target advance angle amount Tvt
14C immediately changes greatly as shown by the solid line in FIG. 14C, whereas the actual advance angle Rvt gradually changes as shown by the broken line in FIG. Then, the actual advance amount R
Until vt reaches the target advance angle Tvt, the actual advance angle Rvt deviates from the target advance angle Tvt and becomes inappropriate for the operating state of the engine 11, and the shaft torque of the engine 11 May fall.

The decrease in the engine output torque will be described with reference to the graph of FIG. This graph also
The change of the shaft torque with respect to the change of the valve timing advance amount Rvt under the condition that the engine speed NE is kept constant is shown by separate solid lines LL3 and LH for each of the cams 72a and 72b.
3.

The engine speed NE decreases to 6000 r
pm, the actual advance angle Rvt becomes equal to the target advance angle T
Assuming that the shaft torque and the lead angle Rvt immediately change in response to a large change in vt, the shaft torque and the advance amount Rvt sequentially change from the state indicated by the point P5 to the state indicated by the points P6 and P7 as indicated by solid arrows in the figure. It will be. However, actually, the advance amount Rvt changes with a delay with respect to the change in the target advance amount Tvt, and the changes in the advance amounts Rvt and Tvt are shifted. As indicated by the two-dot chain line arrow, the state sequentially changes from the state indicated by the point P5 to the state indicated by the points P8 and P7. Due to such a change from the state shown at the point P5 to the state shown at the point P8, a drop occurs in the shaft torque of the engine 11 as shown by the solid line X1 in FIG.

In order to prevent such a drop in the shaft torque, the target advance angle Tvt is changed at a speed of about 6000 rpm with respect to a change in the engine speed NE as shown by a dashed line X2 in FIG.
It is also conceivable to make the transition as shown by. in this case,
Since a large change in the target advance amount Tvt does not occur when the cam is switched, the shaft torque and the advance amount Rvt before and after the cam switch are performed.
Are fixed at the point P2 in FIG. 10 and the point P6 in FIG. 11, so that the drop of the shaft torque of the engine 11 as described above can be prevented. However, in this case 600
Since the target advancing amount Tvt near 0 rpm does not become a value that maximizes the shaft torque, the shaft torque becomes ΔT around 6000 rpm in FIGS. 10 and 11, respectively.
It becomes smaller by the amount indicated by 1 and ΔT2. As a result, the transition tendency of the shaft torque with respect to the change of the engine speed NE becomes as shown by a broken line X3 in FIG. 9A, and although the shaft torque does not drop at the time of cam switching, the shaft torque near 6000 rpm decreases. Would.

Therefore, in the present embodiment, when changing the valve lift amount by switching the cam, FIG.
As shown by a solid line in FIG.
The response speed of the change of the actual advance amount Rvt with respect to the change of t (the response speed of the valve timing change) is increased. By increasing the response speed of the advance amount Rvt in this manner,
It is possible to prevent a drop in the shaft torque at the time of changing the valve lift amount while suppressing a decrease in the shaft torque near 6000 rpm as described above.

Next, an OCV driving duty ratio calculation procedure for determining the response speed of the advance angle amount Rvt will be described with reference to FIG.
8 will be described. FIG. 18 is a flowchart illustrating a duty ratio calculation routine for driving the OCV 49. This duty ratio calculation routine is executed by the ECU 9
2 through, for example, a time interruption every predetermined time.

In the OCV drive duty ratio calculation routine, the ECU 92 performs the process of step SS101 by referring to the map shown in FIG.
And the duty ratio D based on the difference between the advance amounts Tvt and Rvt.
Is calculated. As is apparent from the above map, the calculated duty ratio D decreases as the difference between the advance amounts Tvt and Rvt increases in the negative direction under the condition that the engine speed NE is constant, and the calculated advance ratio D Tvt,
The larger the difference in Rvt is in the plus direction, the larger the difference becomes.

In the process of step S 102, the ECU 92 determines whether or not “0” is stored in a predetermined area of the RAM 95 as the lift amount change flag F. The lift amount change flag F is set to “1” in the processing of step S104 described later when the valve lift amount is changed by switching the cam, and starts counting up when the valve lift amount is changed. When the counter C exceeds a predetermined value a, it is reset to “0” in the processing of step S110 described later. Accordingly, when the valve lift amount is not changed by switching the cam, it is determined that “F = 0” in the process of step S102, and the process proceeds to step S103.

The ECU 92 determines whether or not the valve lift has been changed by switching the cam based on the engine speed NE and the like as the process of step S103. When it is determined that the valve lift has not been changed, the process proceeds to step S110. The ECU 92 determines in step S
In the process at 110, the lift amount change flag F is set to “0”
Is stored in a predetermined area of the RAM 95, the counter C is reset to “0” in the process of step S111, and then the duty ratio calculation routine is temporarily terminated.

When the duty ratio calculation routine is completed, the ECU 92 performs duty control on the voltage applied to the electromagnetic solenoid 49a of the OCV 49 based on the duty ratio D calculated by the processing in step S101. By such duty control, the intake valve 1
9, the actual advance amount Rvt of the valve timing is made closer to the target advance amount Tvt.

If it is determined in step S103 that the valve lift has been changed, the process proceeds to step S104. The ECU 92 determines in step S104
"1" as the lift amount change flag F in the RAM
95 in a predetermined area. Then, step S105
Proceed to. Further, when the lift amount change flag is set to “1” in the processing of step S104, the next step S104
When the process proceeds to step 102, it is determined that “F = 1”, and the process proceeds from step S102 to step S105.

Therefore, when the valve lift amount is changed, it is determined that “F = 1” in the processing of step S102 until a predetermined time elapses after the change, and the process proceeds to step S105. Proceed to steps S105 to S
The processing of 109 is executed. This step S
The processing of 105 to S109 is for increasing or decreasing the duty ratio D for a predetermined period when the valve lift amount is changed.

The ECU 92 increments the counter C by "1" as the process of step S105. This counter C is normally set to “0” by the process of step S111, but starts counting up as described above when the valve lift amount is changed. Subsequently, the ECU 92 determines whether or not the counter C is smaller than a predetermined value a, that is, whether or not a predetermined time has elapsed since the valve lift amount was changed, in the process of step S106.

If it is determined in step S106 that "C <a" is not satisfied and a predetermined period has elapsed since the valve lift was changed, step S110 is performed.
Proceed to. Further, in the process of step S106, “C
If it is determined that the predetermined period has not elapsed since <a> and the valve lift amount is changed, step S107 is performed.
Proceed to. The process in step S107 is performed to determine whether the switching of the cam for changing the valve lift amount is performed from the low-speed cam 72b to the high-speed cam 72a,
This is for determining whether or not the operation has been performed on the low-speed cam 72b.

In the process of step S107, YES
If it is determined that the switching of the cam has been performed from the low-speed cam 72b to the high-speed cam 72a, step S1 is executed.
Proceed to 08. When the process proceeds to step S108, the target advance amount Tvt suddenly increases as shown in FIG. The ECU 92 determines in step S108
As a process of (1), a value obtained by adding “30%” to the duty ratio D calculated in the process of step S101 is set as a new duty ratio D, and then the duty ratio calculation routine is temporarily terminated.

As described above, the duty ratio D is set to “30%”.
Is added, the actual advance amount Rvt of the valve timing of the intake valve 19 follows the sudden increase of the target advance amount Tvt with good responsiveness as shown by the solid line in FIG. It will increase. That is, by adding "30%" to the duty ratio D, the response speed of the change in the advance amount Rvt (response speed of the change in the valve timing) with respect to the increase in the target advance amount Tvt is increased.

By increasing the response speed of the advance amount Rvt in this manner, the time t1 from when the cam shown in FIG. 13 is switched to when the actual advance amount Rvt first reaches the target advance amount Tvt is obtained. That is, it is possible to shorten a period in which the advance amounts Rvt and Tvt are shifted. In addition,
The value “30%” added to the duty ratio D is a value that can minimize the time t1.

Then, the time t1 is shortened and the advance amount R
By shortening the period in which vt and Tvt deviate from each other, it is possible to prevent the shaft torque (output torque) of the engine 11 from dropping in the engine. FIG.
Since there is no need to set the target advance angle Tvt as shown by the broken line X2 in FIG. 9B, the shaft torque around 6000 rpm does not decrease as shown by the broken line X3 in FIG.

When the actual advance Rvt first reaches the target advance Tvt after the cam is switched, the actual advance Rvt is changed to the target advance Tvt as shown in FIG. It fluctuates around and eventually converges to the target advance amount Tvt. When the response speed of the advance amount Rvt is increased as described above, the time t1 can be shortened, but it takes time to converge the actual advance amount Rvt to the target advance amount Tvt. The time t2 increases.

Therefore, in the present embodiment, the actual advance angle Rv
The response speed of t is increased only for a predetermined period after the cam switching, and after the predetermined period has elapsed, the response speed of the translation angle amount Rvt is returned to the normal state. That is, the predetermined period during which the response speed of the actual advance amount Rvt is increased is determined by the value of the predetermined value a used in the process of step S105 (FIG. 18). The predetermined period is set to a value that matches the time t1 shown in FIG.

When the time t1 has elapsed after the cam switching, "30%" is no longer added to the duty ratio D, and the actual response speed of the advance amount Rvt is returned to the normal state. In this state, the response speed of the actual advance angle Rvt is such that the time t2 (FIG. 13) required to converge the advance angle Rvt to the target advance angle Tvt can be minimized. It is said. That is, the advance angle amount Rv at this time
The response speed of t is determined by the duty ratio D calculated based on the map shown in FIG. 17, and the duty ratio D calculated from the map is set in advance so that the time t2 is minimized.

Now, the description returns to the duty ratio calculation routine (FIG. 18). Step S10 in the same routine
In the process of No. 7, if NO and it is determined that the cam has been switched from the high-speed cam 72a to the low-speed cam 72b, the process proceeds to step S109. When the process proceeds to step S109, the target advance amount Tvt suddenly decreases as shown in FIG. ECU 9
2 is the same as the processing in step S109
From the duty ratio D calculated in the process of 101, “30
% Is set as a new duty ratio D, and the duty ratio calculation routine is temporarily terminated.

As described above, from the duty ratio D, “30
% ", The actual advance amount Rvt of the valve timing of the intake valve 19 is reduced as shown in FIG.
As shown by the solid line in FIG. 5, the target follow-up amount Tvt follows the rapid decrease and increases with good responsiveness. That is, by subtracting "30%" from the duty ratio D, the response speed of the change in the advance amount Rvt with respect to the decrease in the target advance amount Tvt (the response speed of the valve timing change) is increased.

By increasing the response speed of the advance amount Rvt in this manner, the time t3 from when the cam shown in FIG. 15 is switched to when the actual advance amount Rvt first reaches the target advance amount Tvt is obtained. That is, it is possible to shorten a period in which the advance amounts Rvt and Tvt are shifted. In addition,
The value “30%” added to the duty ratio D is a value that can minimize the time t3.

Then, the time t3 is shortened and the advance amount R
By shortening the period in which vt and Tvt are shifted, it is possible to prevent the shaft torque (output torque) of the engine 11 from dropping in the engine. FIG.
Since there is no need to set the target advance amount Tvt as shown by the broken line X2 in FIG. 9B, the shaft torque around 6000 rpm does not decrease as shown by the broken line X3 in FIG.

In this case as well, the actual advance Rvt eventually converges to the target advance Tvt as shown in FIG. 15, but in order to shorten the time t4 required for the convergence, After a lapse of a predetermined period for increasing the response speed of the advance angle Rvt, the response speed of the advance angle Rvt is returned to the normal state. That is, the predetermined value a used in the process of step S105 (FIG. 18) is set as a value in which the above-mentioned predetermined period coincides with the time t3 shown in FIG.

When the time t3 has elapsed after the cam switching, "30%" is no longer subtracted from the duty ratio D, and the actual response speed of the advance amount Rvt is returned to the normal state. In this state, the response speed of the actual advance amount Rvt is such that the time t4 (FIG. 15) required to converge the advance amount Rvt to the target advance amount Tvt can be minimized. It is said. That is, the duty ratio D calculated based on the map shown in FIG. 17 is set in advance so that the time t4 is minimized.

According to the present embodiment in which the processing described in detail above is performed, the following effects can be obtained. (1) When the valve lift amount is changed by the switching of the cam, the target advance amount Tvt of the valve timing of the intake valve 19 greatly changes. Tvt
The response speed of the actual advance angle amount Rvt change with respect to the change of is made larger than usual. Therefore, even if the target advance angle Tvt greatly changes as described above, the actual advance angle Rvt follows the change in the target advance angle Tvt with good responsiveness. Therefore, when the valve lift amount is changed, the advance amount Rv
The period during which t and Tvt are shifted (time t in FIGS. 13 and 15)
1, t3) can be shortened to prevent the output torque of the engine 11 from dropping during that period.

(2) Since it is not necessary to set the target advance amount Tvt at the time of changing the valve timing as shown by the broken line X2 in FIG. 9B, the target advance amount Tvt is around 6000 rpm as shown by the broken line X3 in FIG. 9A. Shaft torque (engine output torque) does not decrease.

(3) The response speed of the actual advance amount Rvt is accurately determined by adding or subtracting “30%” to or from the duty ratio D for performing duty control of the voltage applied to the electromagnetic solenoid 49 a of the OCV 49. And the times t1 and t3 are set to be the shortest.
Since the times t1 and t3 are minimized, it is possible to preferably prevent the output torque of the engine 11 from dropping when the valve lift is changed.

(4) Increasing the response speed of the actual advance Rvt allows the advance Rvt to quickly approach the target advance Tvt. The times t2 and t4 (FIGS. 13 and 15) required to converge Rvt to the target advance amount Tvt become longer.
However, the response speed of the actual advance amount Rvt is increased only during a predetermined period after the valve lift amount is changed, so that the actual advance amount Rvt is changed to the target advance amount T when the valve lift amount is changed.
vt, and the target advance amount Tv
t can be quickly converged.

(5) The response speed of the actual advance angle Rvt when the valve lift is not changed is equal to the time t
2 and t4 are set to be the shortest. That is, the duty ratio D calculated based on the map of FIG. 17 is set as a value suitable for making the times t2 and t4 the shortest. Therefore, after the valve timing is changed, the time t1,
For example, after elapse of t3, the actual advance angle Rvt can be promptly converged to the target advance amount Tvt.

(6) When the valve lift amount is changed in two steps by switching the cam for opening and closing the intake valve 19 between the high speed cam 72a and the low speed cam 72b, the lift amount is changed steplessly. When the valve lift amount is changed, the target advance amount Tvt changes greatly as compared with the case where a variable valve lift amount mechanism of the type is adopted. However, by rapidly bringing the actual advance amount Rvt closer to the target advance amount Tvt, it is possible to prevent a drop in output torque when the valve timing is changed due to the cam switching.

The present embodiment can be modified, for example, as follows. In the present embodiment, in the map shown in FIG. 17, the duty ratio D calculated from the map is the actual advance angle Rv.
The time t required to converge t to the target advance amount Tvt
2, t4 is set to be the shortest value,
It is not necessary to set such a map.

In this embodiment, in order to increase the response speed of the change of the actual advance Rvt to the change of the target advance Tvt, the duty ratio D calculated from the map of FIG. Was added or subtracted,
The value “0%” may be changed as appropriate.

In this embodiment, when the valve lift is switched, “30%” is added or subtracted from the duty ratio D calculated based on the map shown in FIG.
Although the response speed of the actual advance amount Rvt is increased, the present invention is not limited to this. That is, when switching the valve lift amount, the duty ratio D may be calculated with reference to a map prepared separately from the map of FIG.
In this case, the duty ratio D calculated based on the separate map is a value that can increase the response speed of the actual advance angle Rvt.

In the present embodiment, the duty ratio D is calculated using a map, but the duty ratio D may be calculated using an equation instead. In this case, the storage capacity of the ROM 93 in which the map is stored can be reduced.

In the present embodiment, the predetermined value a used in the processing of step S105 in the duty ratio calculation routine (FIG. 18) is set so that the predetermined period during which the response speed of the actual advance angle Rvt is increased is time t1, Although it is set so as to coincide with t3, the predetermined value a may be appropriately changed.

In the present embodiment, the opening / closing characteristics of the intake valve 19 are made variable. Instead, the opening / closing characteristics of the exhaust valve 20 are made variable.
The opening and closing characteristics of both 0 may be variable.

In this embodiment, the valve lift variable mechanism 71 of the type that changes the valve lift by switching the cam for opening and closing the intake valve 19 has been described, but the present invention is not limited to this. For example, instead of the variable valve lift mechanism 71, a variable valve lift mechanism that changes the valve lift amount using a three-dimensional cam, or a variable valve lift amount by projecting and retracting a projection from the cam surface of the cam. A variable valve lift mechanism may be employed.

In this embodiment, the variable valve timing mechanism of the vane type is exemplified, but another type of variable valve timing mechanism may be employed. As such a variable valve timing mechanism, there is a variable valve timing type in which a ring piston having a helical spline is reciprocated in the axial direction of the intake camshaft 21 to change the valve timing.

In this embodiment, the valve lift and valve timing of the intake valve 19 are variable. However, the valve lift and valve timing of the exhaust valve 20 may be variable. Further, the valve lift and valve timing of both the intake valve 19 and the exhaust valve 20 may be variable.

Next, technical ideas other than the claims which can be grasped from the above embodiments will be described below together with their effects. (1) In the variable valve operating apparatus for an internal combustion engine according to any one of claims 1 to 3, the response speed control means determines a response speed of the valve timing when the valve lift amount is not changed. A variable valve operating device for an internal combustion engine, wherein the variable value is a value that converges to the target value in a short time.

According to this configuration, when the response speed of the valve timing approaching the target value is increased, the valve timing can quickly approach the target value, but the valve timing converges to the target value. Takes time. However, according to the configuration, when the valve lift amount is not changed, and after the valve timing response speed is returned to the original value after the valve lift amount is changed, the actual valve timing is quickly changed to the target value. Can be converged.

(2) In the variable valve operating apparatus for an internal combustion engine according to any one of claims 1 to 3 and (1), the valve lift amount is changed to one of a high speed and a low speed. A variable valve train for an internal combustion engine, comprising:

According to this configuration, when the valve lift is changed between high speed and low speed, the target value of the valve timing greatly changes. Since the response speed is increased, the actual valve timing can be quickly brought close to the target value to prevent a drop in the engine output torque.

[0111]

According to the first aspect of the present invention, when the valve lift is changed, the target value set in accordance with the engine operating state changes greatly, but the response of the valve timing approaching the target value changes. Since the speed is made larger than when the valve lift amount is not changed, the actual valve timing can quickly approach the target value after the change. Therefore, even if the valve timing target value changes greatly, the period during which the target value deviates from the actual valve timing is shortened, and it is possible to prevent the output torque of the internal combustion engine from dropping during the same period.

According to the second aspect of the present invention, the response speed of the valve timing is increased only until the valve timing reaches the target value for the first time after the valve timing is changed. The timing can be quickly brought close to the target value and quickly converged to the target value.

According to the third aspect of the present invention, by changing the control amount for driving the valve timing variable means, the response speed of the valve timing can be accurately increased. In this case, it is possible to preferably prevent a decrease in the output torque of the internal combustion engine at the time of.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an entire engine to which a variable valve apparatus according to the present invention is applied.

FIG. 2 is a schematic diagram showing a hydraulic circuit of the variable valve operating device.

FIG. 3 is a sectional view showing a variable valve timing mechanism and an oil supply structure thereof.

FIG. 4 is a sectional view showing the internal structure of the variable valve timing mechanism.

FIG. 5 is a perspective view showing a variable valve lift mechanism and an oil supply structure thereof.

FIG. 6 is an enlarged sectional view showing the internal structure of the variable valve lift mechanism.

FIG. 7 is an enlarged sectional view showing the internal structure of the variable valve lift mechanism.

FIG. 8 is a block diagram showing an electrical configuration of the variable valve operating device.

FIG. 9 is a graph showing changes in the shaft torque of the crankshaft with respect to changes in the engine speed and the target advance amount Tvt of the valve timing of the intake valve.

FIG. 10 is a graph showing changes in the shaft torque of the crankshaft and the advance amount Rvt of the valve timing when the cam is switched due to an increase in the engine speed.

FIG. 11 is a graph showing changes in the shaft torque of the crankshaft and the advance amount Rvt of the valve timing when the cam is switched due to a decrease in the engine speed.

FIG. 12 is a time chart showing a cam switching mode when the engine speed increases, and changes in the engine speed NE, the target advance angle Tvt, and the actual advance angle Rvt.

FIG. 13 shows a target advance angle Tvt at the time of the cam switching,
6 is a time chart showing a transition of an actual advance angle Rvt.

FIG. 14 is a time chart showing a cam switching mode when the engine speed decreases, and changes in the engine speed NE, the target advance angle Tvt, and the actual advance angle Rvt.

FIG. 15 shows a target advance amount Tvt at the time of cam switching,
6 is a time chart showing a transition of an actual advance angle Rvt.

FIG. 16 is a map referred to when calculating a target advance angle amount Tvt.

FIG. 17 is a map referred to when calculating a duty ratio for driving an OCV.

FIG. 18 is a flowchart showing a procedure for calculating the duty ratio.

[Explanation of symbols]

11 ... engine, 14 c ... crank sensor, 19 ... intake valve, 20 ... intake valve, 21 ... intake camshaft,
22: exhaust cam shaft, 22b: cam sensor, 24:
Variable valve timing mechanism, 36 ... vacuum sensor,
49 ... Oil control valve (OCV), 71 ... Variable valve lift mechanism, 72a ... High speed cam, 72b ...
Low speed cam, 74 ... oil switching valve (OS
V), 92 ... Electronic control unit (ECU).

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) 3G092 AA01 AA05 AA11 DA01 DA04 DA09 DF04 DF09 DG02 DG05 DG09 EA29 EC02 EC08 FA09 GA14 HA05Z HA13X HA13Z HE01Z HE03Z 3G301 HA01 HA19 JA14 KA11 LA07 LC08 LC10 ND05 PE03

Claims (3)

[Claims] 1. A variable valve operating apparatus for an internal combustion engine, wherein a valve lift amount and a valve timing of the internal combustion engine are made variable. The valve timing approaches a target value set in accordance with an engine operating state with a predetermined response speed. Valve timing variable means, response speed control means for controlling the valve timing variable means so that the response speed of the valve timing when the valve lift amount is changed is larger than the response speed when the valve lift amount is not changed, Variable valve train for internal combustion engine characterized by comprising: 2. The response speed control means increases the response speed of the valve timing only after the valve lift amount is changed until the valve timing reaches the target value for the first time. A variable valve train for an internal combustion engine according to claim 1. 3. The valve timing varying means is driven according to a control amount obtained based on the target value and the actual valve timing, and the response speed control means changes the control amount to change the valve timing. 3. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein a response speed of the variable valve operating speed is increased.