JP3099625B2 - Valve timing control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine having a variable valve timing mechanism for changing the opening / closing timing (valve timing) of at least one of an intake valve and an exhaust valve. The present invention relates to a valve timing control device for controlling the driving of a valve.

[0002]

2. Description of the Related Art Conventionally, a variable valve timing mechanism capable of arbitrarily changing valve timing (opening / closing timing) of an intake valve or an exhaust valve by changing a phase of rotation of a camshaft with respect to rotation of a crankshaft of an engine. Have been proposed. This valve timing is represented by the rotation angle (crank angle) of the crankshaft when the intake and exhaust valves are opened and closed.

As one of the variable valve timing mechanisms, Japanese Patent Laid-Open Publication No. Sho 59-110817 discloses that a valve timing can be continuously changed by changing a rotation angle of a step motor in accordance with an operation state of an engine. Techniques are disclosed. In this technique, a target valve timing according to the operating state is obtained, and a deviation between this value and the valve timing is calculated. The step motor is rotated by the number of steps corresponding to this deviation, and the valve timing is always maintained at the target valve timing.

[0004] Here, the valve timing is not an actually measured value but is determined by an arithmetic processing. Therefore, the determined valve timing may deviate from the actual valve timing. Therefore, in the above technology, a switch such as a limit switch is provided, and when a predetermined reference valve timing (reference value) arrives and the switch is turned on, the valve timing is not determined by arithmetic processing, and the reference value is not determined. Is used as the valve timing at that time. Therefore, every time the switch is turned on, the valve timing determined by the calculation can be corrected, and accurate valve timing control can be performed.

On the other hand, in a vehicle engine of a type in which the valve timing does not change, a concave portion called a valve recess portion is provided on the outer peripheral portion of the top surface of the piston in order to prevent interference between the piston and the intake / exhaust valve. It is known. In determining the depth of the valve recess, it is necessary to satisfy the following two conditions.
Pistons and valves should not come into contact even if the components of the engine vary in size. When the crankshaft and camshaft are driven and connected by a timing belt, the piston and the valve must not come into contact with each other even if the timing belt is incorrectly displaced by several teeth during engine production or inspection. Therefore, the valve recess is formed deeply so that both conditions are satisfied.

[0006]

However, in an engine equipped with the above-described variable valve timing mechanism, when a piston is provided with a valve recess, the following problem occurs. When the valve timing is advanced (advanced) by the variable valve timing mechanism, the valve approaches the piston and the gap between them becomes smaller than when the mechanism is not mounted. This gap becomes minimum when the valve timing is advanced most (at the time of maximum advance). Therefore, in addition to the above, it is necessary to prevent the piston from contacting the valve even at the most advanced angle.

Therefore, when the variable valve timing mechanism is mounted, the valve recess is further deepened by the addition of the above condition. Then, at the top of the piston, the thickness of a portion sandwiched between the annular groove for mounting the piston ring and the valve recess is reduced. Along with this, the rigidity of the same part decreases, and the durability of the piston deteriorates. In addition, since the deep valve recess is provided, the shape of the top of the piston becomes complicated, and there is a possibility that the combustion of fuel may be adversely affected.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide an internal combustion engine equipped with a variable valve timing mechanism in which a valve recess portion of a piston is made shallow to reduce rigidity at a top portion of the piston and reduce flammability. It is an object of the present invention to provide a valve timing control device for an internal combustion engine that can prevent deterioration beforehand.

[0009]

Means for Solving the Problems To achieve the above object, a first aspect of the present invention, as shown in FIG.
An intake valve M6 and an exhaust valve M7 that operate with the rotation of the crankshaft M2 of the internal combustion engine M1 to open and close the intake passage M4 and the exhaust passage M5 communicating with the combustion chamber M3.
Reciprocates with the rotation of the crankshaft M2 in the cylinder M8 communicating with the combustion chamber M3, and has a valve recess M9a at its top for preventing interference with the intake valve M6 and the exhaust valve M7. A piston M9 and at least one valve M corresponding to a crank angle that changes with the rotation of the crankshaft M2.
6, a variable valve timing mechanism M10 for changing the opening / closing timing of M7 within a predetermined angle range, and a valve M on the side provided with the variable valve timing mechanism M10.
6, a timing detecting means M11 for detecting an opening / closing timing of M7, an operating state detecting means M12 for detecting an operating state including a start time of the internal combustion engine M1, and a valve M6 corresponding to an operating state by the operating state detecting means M12. , M7
A target timing calculating means M13 for calculating a target opening / closing timing of the control valve; a control means M14 for driving and controlling the variable valve timing mechanism M10 so that the opening / closing timing by the timing detecting means M11 approaches the target opening / closing timing by the target timing calculating means M13. In the valve timing control device for an internal combustion engine provided with: when the operating state detecting means M12 detects the starting state of the internal combustion engine M1, the target opening / closing timing by the target timing calculating means M13 and the timing detecting means M
A deviation calculating means M15 for calculating a deviation from the opening / closing timing by the valve 11; and when the deviation by the deviation calculating means M15 is larger than a predetermined allowable value, the valve M
The difference between the crank angle when the piston M9 is displaced by the maximum amount toward the piston M9 and the crank angle when the piston M9 is displaced by the maximum amount toward the valves M6 and M7 is the valve M6 and M7.
Target timing changing means M16 forcibly changing the target opening / closing timing of the target timing calculating means M13 so as to be larger than the angle difference at the time of interference between the piston M9 and the piston M9.
Are provided.

[0010] A second invention according to a second aspect is the configuration according to the first aspect, wherein the target timing calculating means M13 comprises:
The target timing changing means M16 calculates the latest timing in the predetermined angle range as the target opening / closing timing of the intake valve M6 when the internal combustion engine M1 is started. It is forbidden to obtain a target opening / closing timing that is earlier than the target opening / closing timing.

[0011]

In the first aspect, as shown in FIG. 1, the intake valve M6 and the exhaust valve M7 operate with the rotation of the crankshaft M2 of the internal combustion engine M1, and the intake passage M
4 and the exhaust passage M5 are opened and closed. Further, the piston M9 reciprocates in the cylinder M8 with the rotation. Then, the piston M9 and the valve M6 (M7) periodically approach and separate from each other. The interval between the two M9, M6 (M7) changes according to the rotation of the crankshaft M2. If this interval becomes zero or negative, the valves M6, M7
Of the valve M enters the valve recess M9a, and the valve M
6, M7 is prevented from contacting the piston M9.

In addition, in the internal combustion engine M1, the valve M
6 and M7, the opening / closing timing of at least one of them is changed by the variable valve timing mechanism M10 as follows. First, the valve M6 on the side provided with the mechanism M10
The opening / closing timing of M7 is detected by timing detecting means M11. The operating state of the internal combustion engine M1 is detected by the operating state detecting means M12. The target opening / closing timing of the valves M6 and M7 according to the operation state is calculated by the target timing calculating means M13. The control unit M1 controls the opening / closing timing to approach the target opening / closing timing.
4 controls the drive of the variable valve timing mechanism M10.

When the opening / closing timing of the valves M6 and M7 is changed as described above, the interval changes accordingly. In general, as the opening / closing timing of the intake valve M6 is advanced (advanced), the interval is narrowed. Therefore, the valve recess M9a has such a depth that the valves M6, M7 and the piston M9 do not come into contact with each other even when the opening / closing timing of the valves M6, M7 is changed to minimize the interval. Become.

If the mechanism M10 is assembled with the opening and closing timings of the valves M6 and M7 deviated from a predetermined timing during the manufacture of the internal combustion engine M1 and the like, the gap may be reduced due to erroneous assembly. Change. If the valve recess M9a is set deeper in consideration of this erroneous assembly, interference between the valves M6 and M7 and the piston M9 is prevented, but problems such as a decrease in strength at the top of the piston M9 and deterioration of flammability arise.

On the other hand, in the first invention, when the operating state detecting means M12 detects the starting state of the internal combustion engine M1, a deviation (deviation) between the target opening / closing timing and the opening / closing timing is obtained by the deviation calculating means M15. Can be At this time, if the variable valve timing mechanism M10 is properly assembled, the deviation is small. However, if the variable valve timing mechanism M10 is incorrectly assembled, the deviation becomes large.

Therefore, when the deviation is larger than a preset allowable value, the target opening / closing timing of the target timing calculating means M13 is forcibly changed by the target timing changing means M16. The variable valve timing mechanism M10 is controlled so that the opening / closing timing approaches the changed target opening / closing timing, so that the valve M
The difference between the crank angle when the piston M9 is displaced by the maximum amount toward the piston M9 and the crank angle when the piston M9 is displaced by the maximum amount toward the valves M6 and M7 is the valve M6 and M7.
And the angle difference when the piston M9 interferes.

As described above, even if the interval between the piston M9 and the valve M6 (M7) becomes narrower than that in the normal assembly due to the erroneous assembly, the two valves M9 and M6 (M7) are opened and closed so as not to come into contact with each other. Timing changes. Therefore, it is not necessary to make the valve recess M9a deep in consideration of erroneous assembly, and the thickness of the top of the piston M9 increases accordingly.

In the second invention, the latest timing in the predetermined angle range as the target opening / closing timing of the intake valve M6 when the internal combustion engine M1 is started is calculated by the target timing calculating means M13. When the deviation is larger than the allowable value, the target timing changing means M16 prohibits the target timing calculating means M13 from obtaining a target opening / closing timing that is earlier than the target opening / closing timing at the time of starting the engine. Due to this prohibition, the opening / closing timing of the valves M6 and M7 is not advanced earlier than the opening / closing timing at the start. That is, even if the internal combustion engine M1 is started while the variable valve timing mechanism M10 is mounted in an incorrect state, the intake valve M6
Is maintained at the latest timing.
At this timing, the interval between the piston M9 and the intake valve M6 is the largest, and the interference between the piston M9 and the intake valve M6 is prevented at the valve recess M9a. Therefore, even if the valve recess M9a is not made deep in consideration of erroneous assembly, the interference is prevented only by prohibiting the arithmetic processing for the advance angle by the target timing calculating means M13. No complicated control is required to cope with erroneous assembly.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the first and second aspects of the present invention will be described below with reference to FIGS.

As shown in FIGS. 2 and 8, the vehicle is equipped with a four-cycle gasoline engine (hereinafter simply referred to as engine) 1 as an internal combustion engine. The engine 1 includes a cylinder block 2 and a cylinder head 3.
A plurality of cylinders 4 extending in the vertical direction are arranged in the cylinder block 2 in parallel in the thickness direction of the drawing, and a piston 5 is accommodated in each cylinder 4 so as to be able to reciprocate. Piston 5
A plurality of annular grooves 20a are formed on the outer periphery of the piston, and a piston ring 20b is mounted on each annular groove 20a. Each piston 5 is connected to a common crankshaft 7 via a connecting rod 6. The reciprocating motion of each piston 5 is converted into a rotational motion by a connecting rod 6 and then transmitted to a crankshaft 7.

As shown in FIG. 2, a combustion chamber 8 is provided above the piston 5 between the cylinder block 2 and the cylinder head 3. The cylinder head 3 is provided with an intake port 9 and an exhaust port 10 for communicating both outer surfaces thereof with the respective combustion chambers 8. In order to open and close these ports 9 and 10, an intake valve 11 and an exhaust valve 12 are supported on the cylinder head 3 so as to be able to reciprocate substantially vertically. In the cylinder head 3, an intake camshaft 13 and an exhaust camshaft 14 are rotatably provided above the valves 11 and 12, respectively. Each camshaft 13,1
4, the timing pulleys 15 and 16 provided at the end of
It is drivingly connected to the crankshaft 7 by a timing belt 17.

When the crankshaft 7 is rotated, the rotation is transmitted to the timing pulleys 15 and 16 via the timing belt 17. When the intake side camshaft 13 rotates with the rotation of the timing pulley 15, the rotation causes the intake valve 11 to reciprocate, and the intake port 9 is opened and closed. Also, when the exhaust side camshaft 14 rotates with the rotation of the timing pulley 16,
The exhaust valve 12 reciprocates by the rotation, and the exhaust port 10 is opened and closed.

Accordingly, as the crankshaft 7 rotates, the piston 5 and the intake / exhaust valves 11 and 12 periodically approach and separate from each other. Then, the distance d between the piston 5 and the valves 11, 12 (the distance between the lower ends of the valves 11, 12 and the top surface 5b, see FIG. 8) changes.

The intake port 9 is connected to an intake passage 23 having an air cleaner 18, a throttle valve 19, a surge tank 21, an intake manifold 22, and the like. Air (outside air) outside the engine 1 sequentially passes through the respective portions 18, 19, 21, and 22 of the intake passage 23 toward the combustion chamber 8.

The throttle valve 19 is rotatably provided in the intake passage 23 by a shaft 24. The shaft 24 is connected to an accelerator pedal (not shown) in the driver's seat via a wire or the like, and is rotated integrally with the throttle valve 19 in conjunction with the depression operation of the accelerator pedal by the driver. At this time, the amount of air flowing through the intake passage 23 (the amount of intake air) is determined according to the inclination angle of the throttle valve 19. The surge tank 21 is for smoothing the pulsation (pressure vibration) of the intake air.

Each intake port 9 is provided in the intake manifold 22.
An injector 25 for injecting fuel toward is mounted. Then, a mixture of fuel injected from each injector 25 and air flowing through the intake passage 23 is:
It is introduced into each combustion chamber 8. To ignite this mixture, an ignition plug 26 is attached to the cylinder head 3.

The ignition plug 26 is connected to a distributor 27
It is driven based on the ignition signal distributed by. The distributor 27 distributes the high voltage output from the igniter 28 to the ignition plug 26 in synchronization with the rotation angle of the crankshaft 7. Then, the air-fuel mixture introduced into the combustion chamber 8 is exploded and burned by the ignition of the spark plug 26. The piston 5 reciprocates by the high-temperature and high-pressure combustion gas generated at this time, the crankshaft 7 is rotated, and the driving force of the engine 1 is obtained.

The exhaust port 10 has an exhaust manifold 2
9. An exhaust passage 32 having a catalytic converter 31 and the like is connected. The combustion gas generated in the combustion chamber 8 passes through the exhaust passage 3
2 are sequentially led out of the engine 1 through the respective members 29 and 31. The catalytic converter 31 has a built-in three-way catalyst 33 for purifying exhaust gas flowing through the exhaust passage 32.

Further, as shown in FIG. 8, in the engine 1 of this embodiment, a valve recess 5a is provided on the outer peripheral portion of the top surface 5b of the piston 5. The valve recess 5a is configured such that the piston 5 rises to near the top dead center with the operation of the engine 1, and the piston 5 and the intake / exhaust valve 1
This is to prevent interference with the exhaust valves 1 and 12 (only the exhaust valve 12 is shown in FIG. 8). The bottom surface of the valve recess 5a is provided with an umbrella portion 12a of the intake / exhaust valve 11, 12.
Is inclined with respect to the top surface 5b of the piston 5 so as to correspond to the shape of.

The depth of the valve recess portion 5a (the distance from the top surface 5b of the piston 5 to the deepest point of the valve recess portion 5a) is determined when the piston 5 rises to near the top dead center. The depth required to prevent contact with the exhaust valves 11 and 12 and the depth necessary to prevent contact between the piston 5 and the intake / exhaust valves 11 and 12 when the components of the engine 1 vary in size. Depth and
This is the sum of the depth required to prevent contact between the piston 5 and the intake / exhaust valves 11 and 12 when the valve timing of the intake valve 11 is advanced by the variable valve timing mechanism described later.

When the timing belt 17 is erroneously attached to the timing pulleys 15 and 16 with a few teeth misaligned at the time of manufacture or inspection of the engine 1, the piston 5 and the piston 5 are not provided with the depth of the valve recess 5 a. Exhaust valve 11,
The depth required to prevent contact with 12 is not included.
Therefore, at the top of the piston 5, the thickness of the portion B sandwiched between the annular groove 20a and the valve recess 5a is:
It is larger than the prior art in which the valve recess is deepened in consideration of erroneous assembly.

As shown in FIG. 2, the following various sensors are attached to the engine 1. A water temperature sensor 34 for detecting the temperature of the cooling water of the engine 1 (cooling water temperature THW) is attached to the cylinder block 2. An intake air temperature sensor 35 for detecting the temperature of the intake air (intake air temperature THA) is attached near the air cleaner 18 in the intake passage 23. In the intake passage 23, near the throttle valve 19, a throttle sensor 36 for detecting the rotation angle of the shaft 24 (throttle opening TA) is provided. The surge tank 21 is provided with an intake pressure sensor 37 for detecting the internal pressure (intake pressure PM). In the middle of the exhaust passage 32, an oxygen sensor 38 for detecting the concentration of residual oxygen in the exhaust gas is mounted.

The distributor 27 has a built-in rotor (not shown) which rotates in synchronization with the rotation of the crankshaft 7. Distributor 27
A rotation speed sensor 3 for detecting the rotation speed NE (engine rotation speed) NE of the crankshaft 7 from the rotation of the rotor
9 are provided. Further, the distributor 27 is provided with a cylinder discrimination sensor 40 for detecting a reference position of the crank at a predetermined ratio from the rotation of the rotor.

Further, the engine 1 is provided with a crank angle sensor 41 comprising a rotor on the crankshaft 7 and an electromagnetic pickup. The rotor is made of a magnetic material, and has a plurality of teeth formed at equal angles on the outer periphery thereof.
The electromagnetic pickup generates a pulse-like crank angle signal each time the rotor rotates and the teeth pass in front of the electromagnetic pickup with the rotation of the crankshaft 7. After the occurrence, the rotation angle (crank angle) of the crankshaft 7 can be detected by measuring the number of occurrences of the crank angle signal from the crank angle sensor 41.

In this embodiment, the throttle sensor 36
And the rotational speed sensor 39 are used as operating state detecting means. A variable valve timing mechanism (hereinafter simply referred to as “VVT”) 46 is provided between the intake side camshaft 13 and the timing pulley 15. VVT
46 is a timing pulley 15 (crankshaft 7)
This is a mechanism for continuously changing the valve timing of the intake valve 11 by changing the phase of rotation of the cam shaft 13 with respect to the rotation of the camshaft 13, and is driven by hydraulic pressure.

Next, the configuration of the VVT 46 will be described with reference to FIGS. The intake-side camshaft 13 is rotatably supported at its journal 47 between the cylinder head 3 and the bearing cap 48. A timing pulley 15 is mounted on the outer periphery of the camshaft 13 near the front of the journal 47 (left side in FIGS. 3 and 5) so as to be relatively rotatable. A large number of external teeth 49 are formed on the outer periphery of the timing pulley 15, and the timing belt 17 is mounted on the external teeth 49. As described above, the rotation of the crankshaft 7 is transmitted to the timing pulley 15 via the timing belt 17.

An inner cap 51 is attached to the front end of the camshaft 13 by a hollow bolt 52 and a pin 53 so as to be integrally rotatable. The timing pulley 15
A cover 55 having a lid 54 is attached so as to be integrally rotatable by bolts 56 and pins 57. This cover 55
The front end of the camshaft 13 and the inner cap 5
1 is entirely covered.

Timing pulley 15 and camshaft 1
3 is connected by a ring gear 58 interposed between the cover 55 and the inner cap 51. The ring gear 58 has a substantially annular shape, and is housed in a space S surrounded by the timing pulley 15, the cover 55, and the inner cap 51 so as to be able to reciprocate in the front-rear direction. A number of teeth 58a, 58b are provided on the inner and outer circumferences of the ring gear 58. Correspondingly, a number of teeth 51a and 55b are provided on the outer periphery of the inner cap 51 and the inner periphery of the cover 55. These teeth 58a, 58b, 51a, 55
b is a helical tooth whose tooth trace intersects the axis of the camshaft 13. And the teeth 51
a and 58a mesh with each other, and the teeth 55b and 58b mesh with each other. The rotation of the timing pulley 15 is transmitted to the camshaft 13 via the cover 55, the ring gear 58, and the inner cap 51 by these meshes. Since the teeth 58a, 58b, 51a, and 55b are helical teeth, when the ring gear 58 moves in the front-rear direction, a torsional force is applied to the inner cap 51 and the cover 55, and as a result, the camshaft 13 It rotates relative to the timing pulley 15.

In the space S, the front side of the ring gear 58 forms a first hydraulic chamber 59, and the rear side forms a second hydraulic chamber 61. As shown in FIG. 2, an existing oil pump 62 is used in the engine 1 to supply the hydraulic pressure by the lubricating oil to each of the hydraulic chambers 59 and 61. Oil pump 62
Is driven and connected to the crankshaft 7 and operates with the operation of the engine 1 to suck and discharge lubricating oil from the oil pan 63. Foreign matter, metal powder, and the like in the discharged lubricating oil are removed by the oil filter 64. Then, the oil pressure of the lubricating oil that has passed through the oil filter 64 is supplied to each of the hydraulic chambers 59 and 61.

As shown in FIGS. 3 and 5, the oil pump 62 is connected to a first hydraulic chamber 59 through a first supply path. That is, a head oil passage 66 extending in the up-down direction is formed in the cylinder head 3 and the bearing cap 48. An oil hole 67 is formed in the bearing cap 48 in parallel with the head oil passage 66. A journal groove 68 is formed over the entire circumference of the camshaft 13 at a location corresponding to the oil hole 67 in the journal 47.

The camshaft 13 has a shaft oil passage 69 extending along its axis. The shaft oil passage 69 is divided into front and rear by a ball 71 arranged on the way. The camshaft 13 has an oil hole 72 penetrating the journal groove 68 and the shaft oil passage 69. The front side of the shaft oil passage 69 is a hollow bolt 5
It communicates with the first hydraulic chamber 59 through the two center holes 52a. Then, the above-described head oil passage 66, oil hole 67,
The journal groove 68, the oil hole 72, the shaft oil passage 69, and the center hole 52a constitute a first supply passage.

The oil pump 62 is in communication with the second hydraulic chamber 61 through a second supply path. That is, the oil hole 74 is formed in the bearing cap 48 in parallel with the oil hole 67. A journal groove 75 is formed over the entire circumference of the camshaft 13 at a location corresponding to the oil hole 74 in the journal 47. In the camshaft 13,
A shaft oil passage 76 is formed in parallel with the shaft oil passage 69. The rear end of the shaft oil passage 76 is connected to the journal groove 75, and the front end is connected to the second hydraulic chamber 6 through an oil hole 77 provided between the camshaft 13 and the inner cap 51.
1 connected. Then, the above-described head oil passage 6
6, oil hole 74, journal groove 75, shaft oil passage 76,
The oil supply hole 77 forms a second supply path.

In the middle of the first supply path and the second supply path, an electromagnetic linear solenoid valve (LS) is used to adjust the magnitude of the hydraulic pressure supplied to each of the hydraulic chambers 59, 61.
V) 78 are provided.

As shown in FIGS. 3 and 4, the casing 79 of the LSV 78 has a first port 81, a second port 82, a third port 83, a fourth port 84 and a Five ports 85 are provided. The first port 81 is connected to the oil hole 67, and the second port 82 is connected to the oil hole 74. Third and fourth
Ports 83 and 84 are connected to the oil pan 63 via oil holes 86 formed in the bearing cap 48. The fifth port 85 is connected to the oil pump 62 via a head oil passage 66, an oil filter 64, and the like.

Inside the casing 79, a spool 87 having four cylindrical valve bodies 87a is accommodated in a reciprocating manner. The spool 87 is provided with springs 88 and electromagnetic solenoids 89 provided on both front and rear sides (left and right in the drawing).
Is moved in the axial direction by the operation of.

For example, as shown in FIG. 6, when the spool 87 is moved forward (to the left in the figure), the fifth port 85 is connected to the first port 81, and the second port 82 is connected to the first port 81. The communication with the fourth port 84 is made. Due to these communications, the hydraulic pressure supplied to the head oil passage 66 is reduced by the LSV 78
The oil is supplied to the first hydraulic chamber 59 through the oil hole 67, the journal groove 68, the oil hole 72, the shaft oil passage 69, and the center hole 52a. When this oil pressure is applied to the ring gear 58 from the front side, the ring gear 58 rotates while moving backward against the lubricating oil in the second hydraulic chamber 61. The movement with this rotation causes the inner cap 51 and the cover 5 to move.
5 is provided with a torsional force.

As a result, the rotation phase of the camshaft 13 with respect to the timing pulley 15 is changed, and the intake valve 1
The valve timing of 1 is advanced. That is, FIG.
As shown in (b), the opening period of the intake valve 11 is advanced, and the period in which both the intake valve 11 and the exhaust valve 12 are open (valve overlap) is expanded. The rearward movement of the ring gear 58 is caused by the timing pulley 1
It is regulated when it comes into contact with 5. When the ring gear 58 comes into contact with the timing pulley 15 and stops, the opening period of the intake valve 11 becomes the earliest.

On the other hand, as shown in FIG. 4, when the spool 87 of the LSV 78 is moved rearward (to the right in the figure), the fifth port 85 is communicated with the second port 82, and
The first port 81 communicates with the third port 83. Then, the hydraulic pressure supplied to the head oil passage 66 becomes LSV 78
The oil is supplied to the second hydraulic chamber 61 through an oil hole 74, a journal groove 75, a shaft oil passage 76, and an oil hole 77. When this hydraulic pressure is applied to the ring gear 58 from the rear side, the ring gear 58 rotates while moving forward against the lubricating oil in the first hydraulic chamber 59. This rotational movement applies a torsional force to the inner cap 51 and the cover 55.

As a result, the rotation phase of the camshaft 13 with respect to the timing pulley 15 is changed, and the intake valve 1
1 is retarded. That is, FIG.
As shown in (a), the valve opening period of the intake valve 11 is delayed, and the valve overlap is reduced and becomes negative. The forward movement of the ring gear 58 is restricted by its contact with the cover 55. When the ring gear 58 comes into contact with the cover 55 and stops, the valve opening period of the intake valve 11 is the latest.

The VVT 46 is configured as described above. By driving the VVT 46, the valve timing of the intake valve 11 and, consequently, the valve overlap are changed, as shown in FIG. 9 (a) and FIG. 9 (b). Can be arbitrarily changed between the states shown in FIG.

When the engine 1 equipped with the VVT 46 is manufactured or inspected at a repair shop, the ring gear 5 is normally used.
The lubricating oil escapes from the hydraulic chambers 59 and 61 around eight.
For this reason, when the engine 1 is started after the manufacture and inspection are completed, the friction of the camshaft 13 causes
Only the timing pulley 15 and the cover 55 are rotated,
The rotation is transmitted to the ring gear 58 via the teeth 55b and 58b. The ring gear 58 moves forward to cover 5
5, the camshaft 13 starts to rotate. Therefore, the intake valve 11 at this time has the most retarded valve timing. Even if lubricating oil remains in both hydraulic chambers 59 and 61, when the engine is started, the LSV is set so that the valve timing is the most retarded as described later.
78 is controlled.

Intake valve 1 changed by VVT 46
In order to detect the first valve timing, the engine 1 is provided with a cam angle sensor 42 as shown in FIG. The sensor 42 includes a rotor on the intake camshaft 13 and an electromagnetic pickup. The rotor is made of a magnetic material, and has a plurality of teeth formed at equal angles on the outer periphery thereof. The electromagnetic pickup generates a pulse-like cam angle signal each time the rotor rotates as the camshaft 13 rotates and the teeth pass in front of the electromagnetic pickup.

The cam angle signal and the crank angle signal are used to determine the amount of change when the rotation phase of the camshaft 13 is changed by the VVT 46. That is, the time required from the generation of the crank angle signal corresponding to the cam angle signal to the generation of another predetermined rotation speed signal is measured, and the rotational phase of the intake camshaft 13 with respect to the crankshaft 7 is determined based on the measured time. The amount of change (displacement angle θ) is calculated. This displacement angle θ corresponds to the opening / closing timing of the intake valve 11.

A warning light 30 is incorporated in the instrument panel at the front of the passenger compartment. The warning light 30
Illuminated when there is a possibility that the piston 5 and the intake valve 11 may come into contact due to erroneous assembly of the timing belt 17.

Each of the injectors 25, the igniter 28, the warning light 3
An electronic control unit (hereinafter simply referred to as “ECU”) 91 is provided to drive and control the LSV 78 and the LSV 78.
The ECU 91 includes, as shown in FIG.
A central processing unit (CP) as target timing calculation means, control means, deviation calculation means and target timing change means.
U) 92, read-only memory (ROM) 93, random access memory (RAM) 94, backup RAM
95, an external input circuit 96 and an external output circuit 97. These units 92 to 97 are connected to each other by a bus 98. The ROM 93 stores a predetermined control program and initial data in advance. The CPU 92 executes various arithmetic processes according to the control program and the initial data. The RAM 94 temporarily stores the calculation result by the CPU 92. The backup RAM 95 stores the ECU 91
A battery (not shown) is used to hold various data in the RAM 94 even after the power supply to the
Have been backed up by

The external input circuit 96 includes the water temperature sensor 34, the intake air temperature sensor 35, the throttle sensor 36, the intake air pressure sensor 37, the oxygen sensor 38, and the rotation speed sensor 3 described above.
9, a cylinder discrimination sensor 40, a crank angle sensor 41, and a cam angle sensor 42 are respectively connected. On the other hand, the external output circuit 97 includes each injector 25, the igniter 2
8, the warning light 30 and the LSV 78 are respectively connected.

Then, the CPU 92 reads, as input values, detection signals of the respective sensors 34 to 42 which are input via the external input circuit 96. Further, the CPU 92 determines each injector 25, the igniter 28, the warning light 3 based on the input value.
0 and the operation of the LSV 78 are controlled to execute fuel injection amount control, ignition timing control, valve timing control, and the like.

For example, when controlling the fuel injection, the CPU 92 controls the engine speed NE by the speed sensor 39.
And the intake pressure PM from the intake pressure sensor 37 are read. The CPU 92 determines the crank angle based on the crank angle detected by the crank angle sensor 41 and the cam angle determined by the cam angle sensor 42.
The change amount (displacement angle θ) of the rotation phase of the intake-side camshaft 13 with respect to the crankshaft 7 is calculated.

The CPU 92 obtains the mass of air charged into each cylinder 4 in one suction stroke based on the engine speed NE, the intake pressure PM and the displacement angle θ. Then, a basic injection time of the fuel according to the air mass is calculated, and the basic injection time is corrected by various correction coefficients to obtain an injection time. CP
U92 outputs a drive signal corresponding to the injection time to the external output circuit 97.
Is output to the injector 25 via the. The valve opening time of the injector 25 is controlled according to this signal, and the amount of fuel corresponding to the time is injected from the injector 25.

Next, the processing content of the valve timing control executed by the CPU 92 will be described with reference to FIG. This valve timing control routine is executed based on a flag F for determining erroneous assembly of the timing belt 17. The flag F is set to “0” when the timing belt 17 is properly assembled, and is set to “1” when the timing belt 17 is mounted on the timing pulley 15 with several teeth shifted.

First, in step 101, the CPU 92 determines whether or not the engine 1 has been started. This determination condition is satisfied, for example, when the starter is turned on and the engine speed NE is equal to or less than a predetermined value (for example, 400 rpm).

If this determination condition is satisfied, the CPU 9
2 calculates a target displacement angle θVTA for making the valve timing the most retarded at the time of engine start in step 102. This target displacement angle θVTA corresponds to a target opening / closing timing of the intake valve 11. The CPU 92 proceeds to step 10
In step 3, a target control amount DV of the LSV 78 corresponding to the target displacement angle θVTA is calculated with reference to a map prepared in advance.

Then, in step 104, the CPU 92 controls the opening of the LSV 78 based on the target control amount DV. With this control, the hydraulic chamber 5 of the VVT 46 is
The magnitude of the hydraulic pressure supplied to the cylinders 9 and 61 is adjusted, the rotation phase of the camshaft 13 is changed, and the valve timing of the intake valve 11 becomes the latest possible timing (the most retarded state).

Subsequently, in step 105, the CPU 92 calculates the actual displacement angle θ using the crank angle of the crank angle sensor 41 and the cam angle of the cam angle sensor 42. That is, the time required from the generation of the crank angle signal corresponding to the cam angle signal to the generation of another predetermined crank angle signal is measured, and based on the time, the intake camshaft 1 with respect to the rotation of the crankshaft 7 is measured.
The change amount (displacement angle θ) of the rotation phase of No. 3 is calculated.

Next, in step 106, the CPU 92 shifts the deviation angle θ from the target displacement angle θVTA (deviation Δθ).
Is calculated. The CPU 92 determines in step 107 that the deviation Δ
It is determined whether or not θ is larger than a predetermined allowable value α. The allowable value α is set to a value slightly smaller than the deviation when the timing belt 17 is assembled with several teeth shifted.

If the determination condition of step 107 is not satisfied (Δθ ≦ α), the CPU 92
7 is determined to be properly assembled to the timing pulley 15, and the flag F is set to "0". On the other hand, when the determination condition is satisfied (Δθ> α), the CPU 92
Determines that the timing belt 17 is mounted on the timing pulley 15 with the teeth shifted by several teeth, and sets the flag F to “1”. And step 108 or 109
Is executed, the CPU 92 once ends this routine.

As described above, when the engine 1 is started, the valve timing of the intake valve 11 is set to the latest possible timing, and erroneous assembly of the timing belt 17 is detected.

On the other hand, if a certain period of time has elapsed since the starter was turned on and the engine rotation speed NE becomes higher than a predetermined value, and the determination condition of step 101 is not satisfied, the CPU 92 proceeds to step 110. Migrate,
It is determined whether or not the flag F is "1". If this determination condition is not satisfied, that is, if the flag F is “0”
, The CPU 92 executes normal valve timing control in steps 111 to 115. That is,
In step 111, the CPU 92 determines the throttle opening degree TA detected by the throttle sensor 36 and the engine rotational speed N detected by the rotational speed sensor 39.
Read E. Subsequently, the CPU 92 proceeds to step 112
In step (2), a target displacement angle θVTA suitable for the driving state at that time is calculated with reference to a predetermined map based on the throttle opening TA and the engine speed NE.

The CPU 92 outputs a drive signal for turning off the warning lamp 30 in step 113. The warning light 30 is turned off in response to this signal.
It can be confirmed that is installed at an appropriate position.

Thereafter, the CPU 92 refers to a map defined in advance in step 114 and refers to the target displacement angle θ.
A target control amount DV of the LSV 78 corresponding to the VTA is calculated. Then, in step 115, the CPU 92 controls the driving of the VVT 46 by controlling the opening of the LSV 78 based on the target control amount DV, and terminates this routine once. As a result, the valve overlap is arbitrarily adjusted and changed according to the operating state of the engine 1.

On the other hand, if the determination condition of the step 110 is satisfied (the flag F is “1”), the CP
If the valve timing is excessively advanced by the operation of the VVT 46, the U92 determines that the intake valve 11 may come into contact with the piston 5 despite the presence of the valve recess 5a, and the target displacement angle θVTA is set to the most retarded angle. Holds the hour value. In other words, the target displacement angle θVTA is prohibited from being changed to a value on the advance side.

That is, in order to prevent interference between the intake valve 11 and the piston 5, it is only necessary to limit the range in which the VVT 46 changes the valve timing. Here, as shown in FIG. 10, the valve timing when the intake valve 11 and the piston 5 come into contact is represented by a characteristic line L0. Further, the crank angle when the intake valve 11 is displaced by the maximum amount toward the piston 5 (the valve lift becomes maximum) and the crank angle when the piston 5 is displaced by the maximum amount toward the intake valve 11 (near top dead center) The angle difference from the angle is represented by β. When the deviation Δθ is larger than a preset allowable value α, that is, in comparison with the valve timing when the timing belt 17 is normally assembled (the characteristic line L1 in FIG. 10), the actual valve timing (in FIG. When the characteristic line L2) is shifted to the advance side by the deviation θ, the angle difference β may be larger than the angle difference β0 when the intake valve 11 and the piston 5 are in contact with each other. The valve timing satisfying this condition exists over a certain angle range (between the characteristic lines L0 and L2).
In this embodiment, the valve timing at the most retarded angle is adopted.

Then, in step 117, the CPU 92 outputs a drive signal for turning on the warning lamp 30. Since the warning light 30 is turned on in response to this signal, the driver can confirm that the timing belt 17 is assembled at an incorrect position by checking the state of the warning light 30.

Thereafter, the CPU 92 proceeds to step 1 described above.
After executing the processing of steps 14 and 115, this routine is temporarily terminated. As a result, the valve timing is maintained at the timing at the time of starting (the latest timing that can be taken at that time). Therefore, even if the interval d between the intake valve 11 and the piston 5 is narrower than normal due to erroneous assembly of the timing belt 17, advancement of the valve timing from the most retarded angle is prohibited. Contact between the piston 11 and the piston 5 is prevented.

As described above, the CPU 92 proceeds to step 105.
Functions as a timing detecting means, and detects the actual opening / closing timing (displacement angle θ) of the intake valve 11. CPU
Reference numeral 92 denotes steps 102 and 112 which function as target timing calculating means to calculate a target opening / closing timing (a target displacement angle θVTA) of the intake valve 11 according to the operating state of the engine 1. In particular, in step 102, the latest timing in the predetermined angle range is calculated as the opening / closing timing of the intake valve 11 when the engine 1 is started. C
The PU 92 functions as control means in steps 103, 104, 114, and 115, and controls the drive of the VVT 46 so that the opening / closing timing approaches the target opening / closing timing.

Further, the CPU 92 functions as a deviation calculating means in step 106, and obtains a deviation Δθ between the target opening / closing timing and the opening / closing timing when the engine is started. CPU
92 functions as target timing changing means in steps 107, 109, 110, and 116, and the deviation Δθ
Is larger than a predetermined allowable value α, the angle difference between the crank angle when the intake valve 11 is displaced by the maximum amount toward the piston 5 and the crank angle when the piston 5 is displaced by the maximum amount toward the intake valve 11 However, the target opening / closing timing is forcibly changed so as to be larger than the angle difference at the time of interference between the intake valve 11 and the piston 5. As a content of this change, the CPU 92 determines in step 116 that the engine 1
Prohibiting the demand for a target opening / closing timing that is earlier than the target opening / closing timing at the start.

Next, the operation and effect of this embodiment will be described. As the crankshaft 7 of the engine 1 rotates, the intake valve 11 operates to open and close the intake passage 23. In addition, the piston 5 moves with the cylinder 4 due to the rotation.
Reciprocate inside. And the piston 5 and the intake valve 11
Periodically approach and leave each other. The distance d between the two 5 and 11 changes according to the rotation of the crankshaft 7. When the distance d becomes zero or negative, the head of the intake valve 11 enters the valve recess 5a, and the contact between the intake valve 11 and the piston 5 is prevented.

In addition, in the engine 1, the valve timing of the intake valve 11 is changed by the VVT 46. With this change, the interval d changes. As for the intake valve 11, the interval d is narrowed as the valve timing is advanced (advanced).
Therefore, the valve recess 5a has a depth that does not allow the intake valve 11 to come into contact with the piston 5 even when the valve timing of the intake valve 11 is changed and the interval d is minimized. .

When the timing belt 17 is assembled with several teeth shifted at the time of manufacture of the engine 1 or the like, and the valve timing of the intake valve 11 is shifted from a predetermined timing, the gap d is set even by the erroneous assembly. Changes. In consideration of this erroneous assembly, the valve recess portion 5a
If is set deeper, interference between the intake valve 11 and the piston 5 is prevented, but a new problem of a decrease in the strength at the top of the piston 5 and a deterioration in flammability arises.

On the other hand, in the present embodiment, when the starting state of the engine 1 is detected, a deviation (shift) Δθ between the target displacement angle θVTA and the displacement angle θ is obtained. At this time, if the timing belt 17 is properly assembled, the deviation Δθ is slight, but if the timing belt 17 is assembled in an incorrect state, the deviation Δθ becomes large.

When the deviation Δθ is larger than the allowable value α, the target displacement angle θVTA is forcibly changed.
The LSV 78 (VVT 46) is controlled so that the displacement angle θ approaches the changed target displacement angle θVTA,
The angle difference β between the crank angle when the intake valve 11 is displaced by the maximum amount toward the piston 5 and the crank angle when the piston 5 is displaced by the maximum amount toward the intake valve 11 is the intake valve 11.
And the angle difference β0 when the piston 5 interferes.

As described above, due to the erroneous assembly, the valve timing is changed so that even if the distance d between the piston 5 and the intake valve 11 becomes narrower than in the normal assembly, the two 5 and 11 do not contact each other. You. Therefore, it is not necessary to make the valve recess 5a deep in consideration of erroneous assembly. Therefore, in the present embodiment, the thickness of the portion B sandwiched between the annular groove 20a of the piston 5 and the valve recess portion 5a is larger than that in the case of preventing interference between the piston and the valve by setting the valve recess portion deep. Become. Therefore, the rigidity of the portion B can be ensured, and the durability of the top of the piston 5 can be improved. Further, since the valve recess 5a can be made shallow, the shape of the top of the piston 5 can be simplified, and deterioration of combustion caused by the shape can be prevented.

In particular, in this embodiment, the latest timing in the predetermined angle range is calculated as the target displacement angle θVTA of the intake valve 11 when the engine 1 is started. When the deviation Δθ is larger than the allowable value α, it is prohibited to obtain the target displacement angle θVTA which is more advanced than the target displacement angle θVTA at the time of starting. This prohibition prevents the valve timing of the intake valve 11 from being advanced earlier than the valve timing at the time of starting. That is, the timing belt 17
Even if the engine 1 is started in a state where it is assembled in an incorrect state, the valve timing of the intake valve 11 is maintained at the latest timing. At this timing, the interval d between the piston 5 and the intake valve 11 becomes the widest, and interference between the piston 5 and the intake valve 11 is prevented by the valve recess 5a. In other words, since the depth of the valve recess 5a originally expects a change in the distance d between the intake valve 11 and the piston 5 due to the advance of the valve timing, the intake air is not advanced unless the valve timing is advanced as described above. No interference between the valve 11 and the piston 5 occurs.

Therefore, even if the valve recess 5a is not made deeper in consideration of erroneous assembly, the interference can be prevented only by prohibiting the calculation process for the advance angle in calculating the target displacement angle θVTA. No complicated control is required to cope with erroneous assembly, and the control can be simplified accordingly.

When the timing belt 17 is erroneously assembled, the valve timing of the intake valve 11 is held at the latest timing as described above, but this does not hinder the running of the vehicle.

The present invention may be embodied with the following modifications other than the above embodiment. (1) The present invention can be applied to the engine 1 in which the valve timing of the intake valve 11 is adjusted to a value intermediate between the most advanced angle and the most retarded angle at the time of starting. In this case, the deviation Δ
When θ is larger than the allowable value α, the crank angle at which the intake valve 11 is displaced by the maximum amount toward the piston 5 and the piston 5 when the intake valve 11 is displaced by the maximum amount It is necessary to drive and control the VVT 46 so that the angle difference from the crank angle at the time of displacement becomes large.

(2) The warning lamp 30 of the above embodiment may be omitted, and the processing of steps 113 and 117 in FIG. 11 may be omitted. In addition, instead of turning on the warning light 30, information (such as a code number) on the erroneous assembly of the timing belt 17 is stored in the backup RAM 95. Then, at the time of inspection at a maintenance shop or the like, the information may be read by a failure diagnosis device. This makes it possible to easily check for erroneous assembly.

(3) A VVT may be provided on the exhaust side camshaft 14, and only the valve timing of the exhaust valve 12 may be changed by the VVT. Further, VVT may be provided on both the intake side and exhaust side camshafts 13 and 14, and the valve timings of the intake valve 11 and the exhaust valve 12 may be respectively changed by the VVT.

(4) In the above embodiment, the VVT 46 driven by hydraulic pressure is used to continuously change the valve timing of the intake valve 11, but the VVT driven by an actuator such as a step motor is used. You may.

(5) The present invention relates to the camshafts 13 and 14
Other valve drive devices, for example, the same camshafts 13, 1
Use an electromagnetically driven valve instead of 4
The present invention is also applicable to an engine that opens and closes an exhaust valve.

[0091]

As described above in detail, in the first invention, the deviation between the target opening / closing timing of the valve and the opening / closing timing at the start of the internal combustion engine is obtained. When the deviation is larger than a preset allowable value, the difference between the crank angle when the valve is displaced by the maximum amount toward the piston and the crank angle when the piston is displaced by the maximum amount toward the valve is the valve and piston. The target opening / closing timing is forcibly changed so as to be larger than the angle difference at the time of interference.

For this reason, at the time of manufacture or inspection of the internal combustion engine, the variable valve timing mechanism is assembled with the opening and closing timing of the valve being different from the preset timing, and the piston and the valve are compared with the normal assembly. Even if the distance between them becomes narrow, interference between them can be prevented. Therefore, it is not necessary to make the valve recess portion deep in consideration of erroneous assembly, and it is possible to prevent the rigidity of the piston top from lowering and the deterioration of the combustibility beforehand.

In the second invention, the latest timing in the predetermined angle range is calculated as the target opening / closing timing of the intake valve when the internal combustion engine is started. When the deviation is larger than the allowable value, it is prohibited to obtain a target opening / closing timing that is earlier than the target opening / closing timing at the time of starting the engine. Therefore, the effects of the above-described first invention can be exerted even without performing complicated control in order to cope with erroneous assembly, and control can be simplified.

[Brief description of the drawings]

FIG. 1 is a conceptual configuration diagram of first and second inventions.

FIG. 2 is a schematic configuration diagram showing an engine and peripheral devices in an embodiment embodying the first and second inventions.

FIG. 3 is a partial cross-sectional view of the VVT when a ring gear is held at a front end position of a movement range in order to operate an intake valve at the latest timing in one embodiment.

FIG. 4 is a partial cross-sectional view of the LSV when the spool is held at a rear end position in a movement range to obtain the state of FIG. 3;

FIG. 5 is a partial cross-sectional view of the VVT when a ring gear is held at a rear end position of a movement range in order to operate an intake valve at the most advanced timing in one embodiment.

6 is a partial cross-sectional view of the LSV when the spool is held at a front end position of a movement range to obtain the state of FIG.

FIG. 7 is a block diagram showing an internal configuration and the like of an ECU in one embodiment.

FIG. 8 is a partial cross-sectional view showing a relationship between an exhaust valve and a valve recess of a piston in one embodiment.

FIGS. 9A and 9B are valve timing diagrams illustrating a period during which an intake valve and an exhaust valve are opened in one embodiment.

FIG. 10 is a characteristic diagram illustrating a relationship between a crank angle and a valve lift amount of an intake / exhaust valve in one embodiment.

FIG. 11 is a flowchart illustrating a “valve timing control routine” executed by a CPU in one embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine as an internal combustion engine, 4 ... Cylinder, 5 ... Piston, 5a ... Valve recess part, 7 ... Crankshaft, 8 ... Combustion chamber, 11 ... Intake valve, 12 ... Exhaust valve, 13 ... Intake as intake valve drive mechanism Side camshaft, 14 ... Exhaust side camshaft as exhaust valve drive mechanism, 23 ... Intake passage, 32 ... Exhaust passage, 42 ... Cam angle sensor as timing detecting means, 46 ... Variable valve timing mechanism (VVT), 92 ... Timing detection means, target timing calculation means, control means, deviation calculation means, CPU as target timing change means, θ: displacement angle corresponding to opening / closing timing, θVTA: target displacement angle corresponding to target opening / closing timing, Δθ: deviation, α: Allowable value.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F02D 13/02 F01L 13/00 301

Claims (2)

(57) [Claims] An intake valve and an exhaust valve that operate with rotation of a crankshaft of an internal combustion engine to open and close an intake passage and an exhaust passage communicating with a combustion chamber, and a rotation of the crankshaft in a cylinder communicating with the combustion chamber. Reciprocating with the piston having a valve recess at its top to prevent interference with the intake and exhaust valves, and at least one of the valves with respect to a crank angle that changes with the rotation of the crankshaft. A variable valve timing mechanism for changing the opening / closing timing within a predetermined angle range; timing detection means for detecting the opening / closing timing of a valve provided with the variable valve timing mechanism; and a time when the internal combustion engine is started. Operating state detecting means for detecting an operating state; and Target timing calculation means for calculating a target opening / closing timing of the valve according to the rotation state; and control means for driving and controlling the variable valve timing mechanism so that the opening / closing timing by the timing detection means approaches the target opening / closing timing by the target timing calculation means. And a deviation between a target opening / closing timing by target timing calculating means and an opening / closing timing by the timing detecting means when the operating state detecting means detects a starting state of the internal combustion engine. When the deviation by the deviation calculating means is larger than a predetermined allowable value, the crank angle when the valve is displaced by the maximum amount toward the piston, and when the piston is displaced by the maximum amount toward the valve side. Angle difference with the crank angle As larger than the angle difference during the interference of the probe and the piston, internal combustion engine valve timing control apparatus provided with a target timing changing means for forcibly changing the target opening and closing timings of the target timing calculation means. 2. The target timing calculating means calculates a latest timing in the predetermined angle range as a target opening / closing timing of the intake valve at the time of starting the internal combustion engine. 2. The valve timing control device for an internal combustion engine according to claim 1, wherein the timing calculation means prohibits obtaining a target opening / closing timing that is earlier than the target opening / closing timing at the time of starting the engine.