JP3360507B2 - 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 intake engine for an internal combustion engine.
The present invention relates to a valve timing control device capable of adjusting the opening / closing timing of an exhaust valve.

[0002]

2. Description of the Related Art Conventionally, in an engine having a variable valve timing mechanism, the variable valve timing mechanism variably operates a valve timing position based on an engine speed and a load (for example, intake air amount, throttle opening, etc.). I'm trying to do it. For example, when the engine speed is high and the load is large and the intake air volume is large, the valve overlap amount is reduced so that the torque characteristics are improved and the high output is maximized. so,
At the time of partial load operation in which the intake air amount is medium, the overlap amount is increased to improve fuel efficiency and exhaust emissions. Further, at the time of idling, the most retarded control is performed to minimize the valve overlap amount, thereby ensuring the engine stability.

[0003]

By the way, in a region where the valve overlap is to be increased in order to improve the exhaust emission and the fuel consumption (at the time of partial load operation), the valve overlap amount is increased to the limit where the combustion becomes unstable. Then, poor driveability occurs. that time,
Since the lower the gear shift position of the transmission is, the easier it is to experience the poor drivability, once the vehicle is running at the valve timing position adapted at the high gear shift position (high gear ratio), if the gear shifts to the low gear shift position (low gear ratio), Drivability may be poor.

On the other hand, if the gear position is changed to a higher gear shift position at a valve timing position suitable for a lower gear shift position, there is a problem that exhaust emission and fuel efficiency cannot be improved.

In the prior art, there has also been proposed a valve timing control device for adjusting the intake or exhaust timing according to the gear shift position of a gear type transmission (Japanese Patent Application Laid-Open No. 64-66414). However, in the proposed technology, the current gear shift position is the reverse, the neutral position is the output characteristic of the low turning point emphasis type, and the second gear is the output characteristic of the high rotation type emphasis type, which is the top. In this case, the valve timing position for obtaining a stable vehicle speed during high-speed cruising is controlled by increasing the engine output characteristics, and there is no disclosure of improving drivability.

The present invention has been made in view of the problems existing in the prior art described above. The internal EGR increases at the time of a high-speed gear, thereby improving fuel efficiency and exhaust emission. An object of the present invention is to provide a valve timing control device for an internal combustion engine that prevents deterioration of drivability because combustion stability can be increased by reducing EGR.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, an invention according to claim 1 is characterized in that at least one of an intake valve and an exhaust valve provided in an intake passage and an exhaust passage of an internal combustion engine has a variable opening / closing timing, A variable valve timing mechanism for changing a valve overlap amount; an operation state detection means for detecting an operation state of the internal combustion engine; and a control means for controlling the valve overlap amount based on a detection result of the operation state detection means. A drive control unit that controls the drive of the variable valve timing mechanism; and a gear position detection unit that detects a gear position of a transmission unit that changes a gear ratio, wherein the drive control unit determines that the detection result of the gear position detection unit is low. A valve timing for an internal combustion engine, wherein the variable valve timing mechanism is controlled such that the internal EGR decreases when the gear is in a gear position. The controller has as its gist.

(Operation) According to the present invention, when the operating state detecting means detects the operating state of the internal combustion engine, the drive control means is varied to control the valve overlap amount based on the detection result of the operating state detecting means. Drive control of the valve timing mechanism. When the gear position detecting means detects the gear position of the speed changing means for changing the gear ratio, the drive control means determines that the detection result of the gear ratio detecting means is a variable valve timing such that the internal EGR decreases when the gear position is the low gear position. Control the mechanism.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in an engine system having a variable valve timing mechanism capable of continuously changing the phase will be described below with reference to FIGS.

FIG. 1 is a schematic diagram showing a gasoline engine (hereinafter referred to as an engine) 1 as an internal combustion engine.
A cylinder bore 3 is formed in the cylinder block 2, and a water temperature sensor 63 for detecting the temperature of cooling water flowing on the outer peripheral surface of the cylinder block 2 is provided. A piston 6 supported by a crankshaft 4 via a rod 5 is disposed in the cylinder bore 3.
The combustion chamber 7 is formed in the cylinder bore 3, and a cylinder head 8 covering the cylinder bore 3 is provided on the upper surface of the cylinder block 2.
Has been fixed. The spark plug 9 is mounted so as to face the combustion chamber 7. The intake passage 10 is an intake port 10
It is connected to the combustion chamber 7 via α and communicates with the exhaust passage 11 from the combustion chamber 7 via an exhaust port 11α.

An intake valve 12 and an exhaust valve 13 are provided at an intake port 10α and an exhaust port 11α, respectively. The intake side camshaft 14 and the exhaust side camshaft 15 are rotatably supported between the cylinder head 8 and the bearing cap 16, respectively. The intake valve 12 and the exhaust valve 13 are opened and closed via a cam (not shown) by rotation of the intake camshaft 14 and the exhaust camshaft 15. Further, an intake-side timing pulley 17 and an exhaust-side timing pulley 18 as rotating bodies are provided at one ends of the camshafts 14 and 15, respectively. Further, each of the timing pulleys 17 and 18 is drivingly connected to the crankshaft 4 via a timing belt 19.

Therefore, when the engine 1 is operating, each of the camshafts 14, 15 from the crankshaft 4 via the timing belt 19 and each of the timing pulleys 17, 18 is provided.
, The intake valve 12 and the exhaust valve 13 are opened and closed. The intake valve 12 and the exhaust valve 13 are synchronized with the rotation of the crankshaft 4, that is, in synchronization with a series of four strokes of an intake stroke, a compression stroke, an explosion / expansion stroke, and an exhaust stroke. Driven by

The air cleaner 20 is provided on the inlet side of the intake passage 10. Also, an injector 2 for fuel injection
1 is provided near the intake port 10α. Then, outside air is taken into the intake passage 10 through the air cleaner 20. Further, by injecting fuel from the injector 21 simultaneously with the intake of the outside air, a mixture of the outside air and the fuel is sucked into the combustion chamber 7 in synchronization with the opening of the intake valve 12 in the suction stroke.

Further, the air-fuel mixture sucked into the combustion chamber 7 is exploded and burned by the operation of the ignition plug 9, whereby the crankshaft 4 is rotated via the piston 6 and the rod 5 to obtain the driving force of the engine 1. Can be Then, the exhaust gas after combustion is discharged from the combustion chamber 7 to the outside via the exhaust port 11α and the exhaust passage 11 in synchronization with the opening of the exhaust valve 13 in the exhaust stroke. Catalytic converter 22
Is provided in the exhaust passage 11 and purifies the exhaust gas by a built-in three-way catalyst.

The throttle valve 23 is provided in the middle of the intake passage 10 and opens and closes in conjunction with the operation of an accelerator pedal 24. By opening and closing the throttle valve 23, the amount of air taken into the intake passage 10 is adjusted. The idle switch 62 is provided on the accelerator pedal 24,
When the accelerator pedal 24 is not operated (the throttle valve 23 is fully closed), the idle signal I of "1"
When the accelerator pedal 24 is operated (the throttle valve 23 is not fully closed), the idle signal IDL of “0” is output. The surge tank 25 is provided downstream of the throttle valve 23 and smoothes intake pulsation. The intake pressure sensor 60 is provided in communication with the surge tank 25 and detects the intake pressure PM.

The spark plug 9 is connected to a distributor 26
And to the igniter 27. The igniter 27 outputs a high voltage, and the distributor 26 applies the high voltage to the ignition plug 9 in synchronization with the rotation angle (crank angle) of the crankshaft 4. The ignition timing of the ignition plug 9 is determined by the output timing of the high voltage from the igniter 27.

The distributor 26 has a rotor (not shown). The rotor is connected to the exhaust camshaft 15 and is rotated in synchronization with the rotation of the crankshaft 4.
The rotation speed sensor 61 is attached to the distributor 26 and detects the engine rotation speed NE from the rotation of the rotor. The cylinder discrimination sensor 56 is connected to the distributor 2
6 and detects a rotation reference position of the crankshaft 4 at a predetermined ratio according to the rotation of the rotor. The crank angle sensor 57 is provided near the crankshaft, and detects the rotation angle of the crankshaft 4 based on the detection timing of the rotation reference position signal of the crankshaft 4 by the cylinder discrimination sensor 56. The cam angle sensor 58 is provided near the intake camshaft 14 and detects a cam angle of the camshaft 14. Further, in this embodiment, a vehicle speed sensor 59 for detecting the running speed (vehicle speed) SPD of the vehicle is provided. The vehicle speed sensor 59 detects the number of rotations of a gear on the output shaft side of the automatic transmission 64 as a speed change means having a gear mechanism capable of switching between three forward speeds and one reverse speed.

In the embodiment of the present invention, the vehicle speed sensor 59, the intake pressure sensor 60, the rotational speed sensor 61, and the idle switch 62 constitute an operating state detecting means for detecting the operating state of the engine 1. Further, a rotation speed detecting means for detecting the rotation speed of the engine 1 by the rotation speed sensor 61 is configured. Further, the crank angle sensor 57 and the cam angle sensor 58 constitute a valve timing detecting means. The vehicle speed sensor 59 forms a vehicle speed detecting means.

A variable valve timing mechanism (hereinafter referred to as VVT) 30 is interposed between the intake side camshaft 14 and the intake side timing pulley 17 to change the opening / closing timing of the intake valve 12. Hereinafter, the same VVT
30 and its peripheral configuration will be described.

As shown in FIG. 2, a cylindrical sleeve 31 is provided.
Is externally fitted to the distal end of the intake-side camshaft 14 and is attached by a hollow bolt 32 and a pin 33 so as to be integrally rotatable. The helical spline 31α is formed on the outer peripheral surface of the sleeve 31.

The intake-side timing pulley 17 is fitted around the front outer periphery of the intake-side camshaft 14 and is disposed between the flange portion 14α of the camshaft 14 and the sleeve 31. The housing 34 is mounted on the front side of the timing pulley 17 so as to surround the tip of the camshaft 14. The space surrounded by the inner peripheral surface of the housing 34 and the front side of the timing pulley 17 is an annular space K. Has made. The helical spline 34α is formed on the inner peripheral surface of the housing 34.

The VVT spool 35 is disposed in the annular space K so as to be movable in the axial direction of the camshaft 14. That is, the cylindrical VVT spool 35 has:
Inner and outer helical splines 35α and 35β are formed on the inner and outer peripheral surfaces, respectively. And the same VVT
The spool 35 is interposed between the sleeve 31 and the housing 34. The inner helical spline 35α is meshed with the helical spline 31α of the sleeve 31, and the outer helical spline 35β is meshed with the helical spline 34α of the housing 34. Therefore, the rotational force of the crankshaft 4 transmitted to the intake-side timing pulley 17 is transmitted to the intake-side camshaft 14 via the VVT spool 35 and the sleeve 31.

A flange portion 35γ is formed on the outer peripheral surface of the VVT spool 35, and an annular space K is defined by a sealing member 35δ of the flange portion 35γ. The space on the front side (left side in the drawing) from the sealing portion formed by the flange portion 35γ is the advance pressure chamber 36, and the space on the rear side (right side in the drawing) is the retard pressure chamber 37.

The first and second hydraulic pressure supply holes 16α, 16β are formed in the bearing cap 16. Also, the first
And the second hydraulic pressure supply passages 14β and 14γ are formed in the intake camshaft 14, and the first hydraulic pressure supply passage 14β connects the first hydraulic pressure supply hole 16α to the advance side pressure chamber 36 via the hollow bolt 32. The second hydraulic pressure supply passage 14γ connects the second hydraulic pressure supply hole 16β to the retard pressure chamber 37.

An oil pump 38 as a hydraulic pressure generating means,
The oil pan 39, the oil filter 40, etc.
The first and second hydraulic supply holes 16α and 16β are provided with electromagnetically controlled oil control valves (hereinafter referred to as OCVs) as operating hydraulic pressure adjusting means.
It is connected to this hydraulic pressure generating means via 41. The OCV 41 is configured such that a plunger 44 driven by an electromagnetic actuator 42 and a coil spring 43 reciprocates a valve spool 45 in an axial direction.
This is a four-port directional control valve that switches the flow direction of hydraulic oil. Then, by controlling the duty ratio of the electromagnetic actuator 42, the opening degree of a port described later is adjusted, and the magnitude of the hydraulic pressure supplied to each of the pressure chambers 36 and 37 is adjusted.

That is, the casing 46 of the OCV 41
Are tank port 46α, A port 46β, B port 4
6γ and a reservoir port 46δ. And
The tank port 46α is connected to an oil pan 39 via an oil pump 38 and an oil filter 40.
The port 46β is connected to the first hydraulic pressure supply hole 16α and the B port 46
γ is connected to each of the second hydraulic pressure supply holes 16β.
Further, the reservoir port 46δ is communicated with the oil pan 39.

The valve spool 45 is a cylindrical valve body, and has four lands 45α for sealing the flow of hydraulic oil between the two ports 46β and 46γ, and two ports 46.
It has a central passage 45β communicating between β and 46γ and allowing the flow of hydraulic oil, and two passages 45γ located on both sides of the central passage 45β.

In the VVT 30 having these structures, when the electromagnetic actuator 42 is excited by the maximum exciting current (duty ratio = 100%), and the valve spool 45 is moved to the left in the drawing against the coil spring 43, Is the center passage 45β is tank port 46α and A
The operating oil is supplied to the first hydraulic pressure supply hole 16α by communicating with the port 46β. Then, the hydraulic oil supplied to the first hydraulic pressure supply hole 16α is supplied to the advance pressure chamber 36 via the first hydraulic pressure supply path 14β, and the hydraulic pressure is applied to the tip side of the VVT spool 35. The connection amount between the first hydraulic pressure supply hole 16α and the tank port 46α is maximum (100%).

At the same time, the passage 45γ on the right side in the figure is
Communicates the B port 46γ with the reservoir port 46δ, and the hydraulic oil in the retard pressure chamber 37 is supplied to the second hydraulic supply passage 1
4γ, the second hydraulic pressure supply hole 16β, and the B port 46γ of the OCV 41 are discharged to the oil pan 39. This second
The connection amount between the hydraulic pressure supply hole 16β and the reservoir port 46δ is maximum (100%).

Therefore, the VVT spool 35 is moved at the maximum speed while rotating to the rear end side (rightward in the drawing) by the hydraulic pressure applied to the front end side, and twisted to the intake side camshaft 14 via the sleeve 31. Is given. As a result, the relative rotation phase of the intake side camshaft 14 with respect to the intake side timing pulley 17 (crankshaft 4) is changed, and the camshaft 14 rotates from the most retarded position to the most advanced position, and the intake valve 12 Is advanced. The VVT spool 35 contacts the intake-side timing pulley 17 to restrict further movement, and when the VVT spool 35 is displaced to the contact position (the most advanced position), the intake valve 12 is stopped. Becomes the earliest.

On the other hand, when the electromagnetic actuator 42 is deenergized (duty ratio = 0%), the valve spool 45 is moved rightward in the drawing by the urging force of the coil spring 43. Then, the central passage 45β communicates the tank port 46α with the B port 46γ, and hydraulic oil is supplied to the second hydraulic pressure supply hole 16β. The hydraulic oil supplied to the second hydraulic supply hole 16β is supplied to the second hydraulic supply passage 1
The pressure is supplied to the retard pressure chamber 37 via 4γ, and the hydraulic pressure is applied to the rear end of the VVT spool 35. The connection amount between the second hydraulic pressure supply hole 16β and the tank port 46α is maximum (1
00%).

At the same time, the passage 45γ on the left side in FIG.
Communicates the A port 46β with the reservoir port 46δ, and the hydraulic oil in the advance side pressure chamber 36 is supplied to the first hydraulic supply passage 1
4β, the first oil pressure supply hole 16α, the A port 46β of the OCV 41, and the reservoir port 46δ,
It is discharged to 9. The connection amount between the first hydraulic pressure supply hole 16α and the reservoir port 46δ is maximum (100%).

Accordingly, the VVT spool 35 is moved at the maximum speed while rotating to the front end side (left side in the drawing) by the hydraulic pressure applied to the rear end side, and is directed in the opposite direction to the intake side camshaft 14 via the sleeve 31. Is imparted. As a result, the rotation phase of the intake side camshaft 14 with respect to the intake side timing pulley 17 (crankshaft 4) is changed, and the camshaft 14 rotates from the most advanced position to the most retarded position. The valve opening timing is retarded. The VVT spool 35 contacts the housing 34 of the pulley 17 to restrict further movement, and when the VVT spool 35 is displaced to this contact position (most retarded position), the intake valve 12 Becomes the latest.

As described above, the electromagnetic actuator 42
Is changed between 0% and 100%, the stroke of the VVT spool 35 is changed. Therefore, the first and second hydraulic supply holes 16α, 16
the connection amount between β and the tank port 46α, and the first and second
The amount of connection between the hydraulic pressure supply holes 16α, 16β and the reservoir port 46δ is changed between 0% and 100%, and the moving speed of the VVT spool 35 to the most advanced side or the most retarded side is changed.

Here, when the electromagnetic actuator 42 is controlled by a certain duty ratio, the valve spool 4
5 is displaced by its land 45α to a position that closes the A port 46β and the B port 46γ. Therefore, the first and second hydraulic pressure supply holes 16α, 16β and the tank port 46α,
And the connection amount between the first and second hydraulic pressure supply holes 16α and 16β and the reservoir port 46δ is 0%, and the VV
The T spool 35 is not displaced to either the advance side or the retard side (the moving speed becomes zero), and is held at that position. A signal corresponding to this duty ratio is predetermined as a holding duty value GDVTH. Then, in the embodiment of the present invention, this holding duty value GDVT
H is updated by learning in order to remove errors due to component tolerances, aging, and the like.

Next, an electronic control unit (EC) for controlling the engine 1 having the VVT 30 according to the embodiment of the present invention.
The electrical configuration of U) 50 will be described with reference to the block diagram of FIG.

The ECU 50 constituting the drive control means and the gear position detection means according to the embodiment of the present invention includes a CPU (central processing unit) 51 and a ROM (ROM) storing various programs including a "VVT calculation routine" described later. A read-only memory) 52 and a RAM (readable / writable memory) 53 for temporarily storing various information.

Cylinder discrimination sensor 56, crank angle sensor 5
7, the cam angle sensor 58, the vehicle speed sensor 59, the intake pressure sensor 60, the rotation speed sensor 61, the idle switch 62, and the water temperature sensor 63 are connected to the CPU 5 via an external input circuit 54.
1 connected.

The OCV 41 (electromagnetic actuator 42), the injector 21 and the igniter 27 are connected to the CPU 51 via an external output circuit 55. The CPU 51 preferably controls the OCV 41, the injector 21 (fuel injection timing, etc.), the igniter 27 (ignition timing, etc.) based on signals from the sensors 56 to 61, the idle switch 62, and the like, according to a control program stored in the ROM 52. To control.

Next, a program relating to valve timing control in the valve timing control apparatus for an internal combustion engine having the above configuration will be described with reference to the flowchart of FIG. This flowchart is a "VVT calculation routine" for calculating a target valve timing VTT for controlling the drive of the VVT 30, and is periodically executed at predetermined time intervals.

First, in step (hereinafter, step is referred to as S) 101, it is determined whether or not the idle signal IDL is "0", that is, whether or not the idle signal is off. This S
In 101, it is determined whether or not the accelerator pedal is operated. If the idle signal IDL is not “0” but “1”, it is determined that the accelerator pedal has not been operated, and the process shifts to S106 to refer to the idle-on VTT map shown in FIG. The target displacement angle VTTN at the time of idling is searched based on. The idle-on VTT map is a map of valve timing obtained in advance through experiments or the like so as to obtain a suitable output characteristic corresponding to the engine speed NE at the time of idling. And the next S1
At 07, the retrieved idling target displacement angle VTT
N is stored in the RAM 53 as the target valve timing VTT, and the process exits from this routine.

In step S101, if the idle signal IDL is "0", it is determined as "YES", that is, it is determined that the idle is off. Next, the process proceeds to S102, and the idle-off target displacement angle base value VTTB is searched based on the engine speed NE and the intake pressure PM with reference to the idle-off VTT map shown in FIG. The idle-time VTT map maps valve timings obtained in advance through experiments and the like so as to obtain suitable output characteristics in accordance with the respective engine speed NE and intake pressure PM at the time of idle-off. Things.

This map shows that when the engine speed NE is high and the intake pressure PM is full load, the valve overlap amount is reduced, the torque characteristics are improved, and the high output is maximized. Is set to the target displacement angle base value VTTB, the engine speed NE is medium, the intake pressure PM
In the middle partial load operation, the target displacement angle base value VTTB is set in order to increase the overlap amount and improve the fuel efficiency and the exhaust emission.

Next, in S103, it is determined whether the gear position determination index NVR is larger or smaller than a determination value α. The gear position determination index NVR is obtained by the following equation. Gear position determination index NVR = engine speed NE / vehicle speed S
PD The discrimination value α is determined as follows.

The gear position determination index NVR is calculated for each gear position,
That is, since a substantially constant value is obtained at the shift position of the automatic transmission 64, in this embodiment of three forward speeds,
The value between the gear position determination index at rd and the gear position determination index at 2nd is defined as the determination value α. Therefore, if the gear position determination index NVR is larger than the determination value α, the gear position in the current running state is determined to be the second or first low gear position (low gear ratio), and the gear position determination index NVR is determined to be the determination value α. If smaller, it is determined to be a 3rd high-speed gear position (high-speed gear ratio).

In S103, the gear position determination index NV
When it is determined that R is smaller than the determination value α, ie, 3
If it is determined that the rd high-speed gear position (high-speed gear ratio), S1
08, the target displacement angle base value VTTB is stored as it is in the RAM 53 as the target valve timing VTT, and the routine exits.

Conversely, if it is determined in S103 that the gear position determination index NVR is larger than the determination value α, that is, if it is determined that the gear position is the second or first low gear position (low gear ratio), the process proceeds to S104, and The low-speed gear correction value VTTLG is searched based on the engine speed NE and the intake pressure PM with reference to the gear correction map.

The low-speed gear correction value VTTLG is set for the following reason. VT at idle-off
In the T map, when the shift position of the automatic transmission is in the high gear position at the time of partial load, the valve timing is such that the overlap is enlarged so that the fuel efficiency and emission are most improved. However, if this overlap is expanded to the limit where combustion becomes unstable, drivability will be poor, but this drivability defect will occur when the shift position of the automatic transmission is lower in the low gear position than in the high gear position. Easy to feel. Accordingly, if the valve timing is the same as that of the high-speed gear position at the low-speed gear position, the frequency of occurrence of poor drivability and the like increases. In order to reduce the lap and suppress the occurrence of poor drivability, an optimal value is previously selected as the correction value by experiments or the like so that the drivability does not deteriorate at the low gear position.

Therefore, in the low gear position, the target displacement angle base value VT during idle-off when the gear is in the high gear position.
The low-speed gear correction value VTTLG is set as a correction value for delaying the valve timing more than TB.

In step S104, the low-speed gear correction value VTT
When the LG search is completed, in S105, the low-speed gear correction value VTTLG is subtracted from the idle-off target displacement angle base value VTTB, the result of the subtraction is stored in the RAM 53 as the target valve timing VTT, and the routine exits.

When the VTT calculation routine is completed as described above, the CPU 51 executes the drive control of the VVT 30. In this drive control, first, the actual valve timing VT of the VVT 30 is calculated from the values detected by the cam angle sensor 58 and the crank angle sensor 57.

Next, the calculation of the drive duty value DVT is calculated by the following equation. DVT = GDVTH + K × (VTT−VT) In the above equation, GDVTH is the aforementioned VVT spool 3
5 represents a holding duty value for holding 5 at an arbitrary position, and K represents a proportional control gain value.

By outputting the drive duty value DVT, the VVT 30 is feedback-controlled so that the actual valve timing VT converges to the target valve timing VTT. Then, when the actual valve timing VT converges to the target valve timing VTT (VTT
= VT), the holding duty value GDVTH is output, and therefore, the phase holding control of the VVT 30 at the target valve timing VTT is performed. (A) In the embodiment configured as described above, at the time of the high-speed gear position (high-speed gear ratio) in S103, the target displacement at idle-off is set so that the valve timing at which the overlap is enlarged is set. Angle base value V
TTB is set as the target valve timing VTT. Therefore, in this case, the internal EGR can be increased,
Fuel efficiency and emissions are improved.

If it is determined in S103 that the vehicle is at the low gear position (low gear ratio), the low gear correction value VTTLG is subtracted from the idle-off target displacement angle base value VTTB at the high gear position. The valve timing is delayed from the valve timing at the high gear position. As a result, the valve overlap is reduced, the internal EGR is reduced, and the combustion stability is increased, so that the drivability can be prevented from deteriorating. (B) In this embodiment, the CPU 51 calculates the gear position determination index NVR from the engine speed NE and the vehicle speed SPD and compares the NVR with the determination value α to detect the gear position. As a result, the automatic transmission 64
Since a shift position sensor is not required and the software is used, the number of parts can be reduced, and the cost can be reduced.

The present invention can be practiced in the following modes without departing from the spirit of the present invention. (A) In the above embodiment, V is set to the valve on the intake side.
VT30 was provided. This may be changed, and the VVT 30 may be provided on the exhaust side valve, or the VVT 30 may be provided on both valve sides. (B) In the above embodiment, the idle switch is used to determine whether or not the engine is in the idle state. However, a throttle opening sensor for detecting the opening of the throttle may be used instead. (C) In calculating the target valve timing VTT, other parameters such as the throttle opening and the intake air amount may be used. (D) In the above embodiment, the determination value α is set to a value between the gear position determination indices of 3rd and 2nd in the automatic transmission of three forward speeds. However, the present invention is not limited to this speed. In an automatic transmission having a gear mechanism capable of shifting a plurality of speeds, the determination value α may be set between a low gear position and a high gear position. (E) A diesel engine system may be embodied instead of a gasoline engine system. (F) In the above embodiment, the gear position determination index NVR is calculated, and the gear position is detected by comparing the NVR with the determination value α. May be provided to detect the shift position.

The technical ideas which can be grasped from the embodiment of the present invention will be described together with the effects. (1) The valve timing control device for an internal combustion engine according to claim 1, wherein the variable valve timing mechanism continuously changes at least one of opening and closing timings of an intake valve and an exhaust valve. By doing this,
In the exhaust valve, the same functions and effects as those of the above embodiment can be obtained. (2) The valve timing control device for an internal combustion engine according to claim 1, wherein the gear position detecting means determines the gear position based on a ratio between the vehicle speed and the engine speed detected by the operating state detecting means. Since the shift means does not require a shift position sensor and is compatible with software, the number of parts can be reduced, and the cost can be reduced.

[0057]

As described above in detail, according to the present invention, the internal EGR increases at the time of a high-speed gear, so that the fuel efficiency,
Exhaust emissions can be improved and the internal E
Since the combustion stability can be increased by reducing the GR, an excellent effect of preventing deterioration of drivability can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an engine.

FIG. 2 is a schematic configuration diagram of a variable valve timing mechanism and its peripheral configuration.

FIG. 3 is a block diagram showing an electrical configuration of an ECU.

FIG. 4 is a flowchart showing a VTT calculation routine according to the embodiment of the present invention.

FIG. 5 is an explanatory diagram showing an idle-on map.

FIG. 6 is an explanatory diagram showing an idle-off VTT map.

FIG. 7 is an explanatory diagram showing a low-speed gear correction map.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Gasoline engine as an internal combustion engine, 12 ... Intake valve, 14 ... Intake side camshaft, 17 ... Intake side timing pulley, 30 ... Variable valve timing mechanism (valve timing control mechanism), 35 ... VVT spool, 35α
... Inner helical spline, 35β ... Outer helical spline, 36 ... Advance side pressure chamber, 37 ... Retardation side pressure chamber, 3
8 oil pump, 41 oil control valve as operating oil pressure adjusting means, 50 ECU constituting gear position detecting means and drive control means, 59 to 62 sensors and switches constituting operating state detecting means, 61 rotation Number sensor, 64: automatic transmission constituting a transmission means.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F02D 13/02 F01L 1/34 F02D 29/00 F02M 25/07 510

Claims (1)

(57) [Claims] 1. A variable valve timing mechanism for changing at least one of an intake valve and an exhaust valve provided in an intake passage and an exhaust passage of an internal combustion engine to change a valve overlap amount, and operating the internal combustion engine. Operating state detecting means for detecting a state; driving control means for driving and controlling the variable valve timing mechanism to control the valve overlap amount based on a detection result of the operating state detecting means; Gear position detection means for detecting the gear position of the means, wherein the drive control means controls the variable valve timing mechanism such that the internal EGR decreases when the detection result of the gear position detection means is a low gear position. A valve timing control device for an internal combustion engine, comprising: