JPH09158749A - Valve timing control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of the driveability by increasing the inner EGR to improve the fuel consumption and the exhaust emission in the high speed gear position, and reducing the inner EGR to increase the combustion stability in the low speed gear position. SOLUTION: The opening/closing timing of an intake valve 12 of an engine 1 is variable, a variable valve timing mechanism 30 to change the valve overlap is provided, and an engine speed sensor 61 of the engine 1 and an intake air pressure sensor 60 are provided. An electronic control unit(ECU) 50 controls the drive of the variable valve timing mechanism 30 so as to control the valve overlap by the engine speed and the intake air pressure detected by the engine speed sensor 61 and the intake air pressure sensor 60. The ECU 50 detects the gear position from the engine speed and the vehicle speed ratio detected by a vehicle speed sensor 59. The ECU 50 controls the variable valve timing mechanism 30 so that the inner EGR is reduced when the detected result of the gear position is the low speed gear position.

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 varies the valve timing position based on the engine speed and load (for example, intake air amount, throttle opening, etc.). I am trying to do it. For example, when the engine speed is high and the intake air amount is large at full load, the valve overlap amount is reduced so that the torque characteristics are improved and the high output is maximized. so,
During partial load operation where the intake air amount is medium, the overlap amount is expanded to improve fuel efficiency and exhaust emission. Further, at the time of idling, the most retarded angle control is performed to minimize the valve overlap amount to ensure the engine stability.

[0003]

By the way, in a region where it is desired to increase the valve overlap in order to improve exhaust emission and fuel economy (during partial load operation), the valve overlap amount is increased to the limit where combustion becomes unstable. Then, a drivability defect occurs. that time,
The lower the gear shift position of the transmission is, the easier it is to experience poor drivability, so once the vehicle is traveling at a valve timing position that is suitable for a high gear shift position (high speed gear ratio), it changes to a low gear shift position (low speed gear ratio). Deterioration of drivability may occur.

On the contrary, if the valve timing position adapted to the low gear shift position is changed to the high gear shift position, there is a problem that exhaust emission and fuel consumption cannot be improved.

In the prior art, there is also proposed a valve timing control device which adjusts the intake or exhaust timing according to the gear shift position of the gear type transmission (Japanese Patent Laid-Open No. 64-66414). However, in this proposed technology, the output characteristic of the low gear point is emphasized when the current gear shift position is backward and the neutral position, and the output characteristic of the high rotation type is emphasized in the case of the 2nd speed, which is the top. In this case, the valve output position is controlled in order to obtain a stable vehicle speed during high-speed cruising by increasing the engine output characteristic, and improvement of drivability is not disclosed.

The present invention has been made by paying attention to the problems existing in the above-mentioned prior art. In the high speed gear, the internal EGR is increased to improve fuel consumption and exhaust emission, and in the low speed gear, the internal EGR is improved. Since combustion stability can be increased by reducing EGR, it is an object of the present invention to provide a valve timing control device for an internal combustion engine that prevents deterioration of drivability.

[0007]

In order to achieve the above object, the invention of claim 1 makes variable the opening / closing timing of 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, A variable valve timing mechanism for changing the valve overlap amount, an operating state detecting means for detecting the operating state of the internal combustion engine, and the valve overlap amount for controlling the valve overlapping amount based on the detection result of the operating state detecting means. The drive control means includes drive control means for driving and controlling the variable valve timing mechanism, and gear position detection means for detecting the gear position of the transmission means for changing the gear ratio. A valve timing control system for an internal combustion engine, characterized in that a variable valve timing mechanism is controlled so that the internal EGR is reduced when in a gear position. The controller has as its gist.

According to the present invention, when the operating state detecting means detects the operating state of the internal combustion engine, the drive control means changes the valve overlap amount based on the detection result of the operating state detecting means. Drive control of the valve timing mechanism. Further, when the gear position detecting means detects the gear position of the transmission means for changing the gear ratio, the drive control means causes the variable valve timing so that the internal EGR decreases when the detection result of the gear ratio detecting means is the low speed gear position. Control the mechanism.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is embodied in an engine system equipped with a variable valve timing mechanism capable of continuously changing the phase will be described with reference to FIGS.

FIG. 1 is a schematic configuration 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 the cooling water flowing on the outer peripheral surface of the cylinder block 2 is arranged. A piston 6 supported by a crankshaft 4 via a rod 5 is arranged 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 the 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 the exhaust port 11α.

The intake valve 12 and the exhaust valve 13 are provided in the intake port 10α and the 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. Then, the intake valve 12 and the exhaust valve 13 are opened and closed via a cam (not shown) by the rotation of the intake camshaft 14 and the exhaust camshaft 15. An intake side timing pulley 17 and an exhaust side timing pulley 18 as rotating bodies are respectively provided at one ends of the camshafts 14 and 15. Further, the timing pulleys 17 and 18 are drivingly connected to the crankshaft 4 via a timing belt 19.

Therefore, during operation of the engine 1, the camshafts 14 and 15 are driven from the crankshaft 4 through the timing belt 19 and the timing pulleys 17 and 18, respectively.
The rotational power is transmitted to the intake valve 12 and the exhaust valve 13 to open and close. The intake valve 12 and the exhaust valve 13 have predetermined opening / closing timings in synchronization 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. In addition, the 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, the fuel is injected from the injector 21 simultaneously with the intake of the outside air, so that the 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 intake 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, and the driving force of the engine 1 is obtained. To be Then, the exhaust gas after combustion is discharged to the outside from the combustion chamber 7 through 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 middle of 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 is opened / closed in conjunction with the operation of the accelerator pedal 24. By opening / closing the throttle valve 23, the amount of intake air 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" is output.
When DL is output and the accelerator pedal 24 is operated (throttle valve 23 is in a non-fully closed state), an idle signal IDL of "0" is output. The surge tank 25 is provided on the downstream side of the throttle valve 23 and smoothes the 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 a distributor 26.
It is connected to the igniter 27 via. 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 spark plug 9 is determined by the output timing of the high voltage from the igniter 27.

The distributor 26 has a rotor (not shown), which is connected to the exhaust side 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. Further, the cylinder discrimination sensor 56 is the distributor 2
The rotation reference position of the crankshaft 4 is detected at a predetermined ratio according to the rotation of the rotor. The crank angle sensor 57 is provided in the vicinity of 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 arranged near the intake side camshaft 14 and detects the cam angle of the camshaft 14. Further, in this embodiment, a vehicle speed sensor 59 for detecting the traveling 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 an automatic transmission 64 as a transmission unit having a gear mechanism capable of switching between three forward gears and one reverse gear.

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

The 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. Below, the same VVT
30 and its peripheral configuration will be described.

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

The intake side timing pulley 17 is fitted onto the outer periphery of the front part of the intake side camshaft 14 and is arranged between the flange portion 14α of the camshaft 14 and the sleeve 31. The housing 34 is attached to the front side surface of the timing pulley 17 so as to surround the tip end portion of the cam shaft 14, and the space surrounded by the inner peripheral surface of the housing 34 and the front side surface of the timing pulley 17 is an annular space K. Is doing. The helical spline 34α is formed on the inner peripheral surface of the housing 34.

The VVT spool 35 is arranged in the annular space K so as to be movable in the axial direction of the camshaft 14. That is, in the cylindrical VVT spool 35,
Inner and outer helical splines 35α and 35β are formed on the inner and outer peripheral surfaces thereof, respectively. And the same VVT
The spool 35 is interposed between the sleeve 31 and the housing 34, and 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 (on the left side in the drawing) from the sealing portion by the flange portion 35γ is the advance side pressure chamber 36, and the space on the rear side (on the right side) is the retard side pressure chamber 37.

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

An oil pump 38 as a hydraulic pressure generating means,
The oil pan 39, the oil filter 40, etc. are the engine 1
The first and second hydraulic pressure supply holes 16α and 16β are electromagnetic control type oil control valves (hereinafter referred to as OCV) as operating hydraulic pressure adjusting means.
It is connected to this hydraulic pressure generating means via 41. In this OCV 41, the plunger 44 driven by the electromagnetic actuator 42 and the coil spring 43 reciprocates the valve spool 45 in the axial direction,
It is a 4-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 the port described later is adjusted, and the magnitude of the hydraulic pressure supplied to the pressure chambers 36, 37 is adjusted.

That is, the casing 46 of the OCV 41
Is tank port 46α, A port 46β, B port 4
It has 6γ and a reservoir port 46δ. And
The tank port 46α is connected to the oil pan 39 via the oil pump 38 and the oil filter 40, and
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 communicates 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 that communicates between β and 46γ and allows the flow of hydraulic oil, and two passages 45γ positioned on both sides of the central passage 45β.

In the VVT 30 having these configurations, when the electromagnetic actuator 42 is excited by the maximum exciting current (duty ratio = 100%) and the valve spool 45 is moved leftward in the drawing against the coil spring 43. Is the central passage 45β and tank port 46α and A
The hydraulic 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 side pressure chamber 36 via the first hydraulic pressure supply passage 14β, and the hydraulic pressure is applied to the front end 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 of the figure
Communicates the B port 46γ and the reservoir port 46δ, and the hydraulic oil in the retard angle side pressure chamber 37 is the second hydraulic pressure supply passage 1
4γ, the second hydraulic pressure supply hole 16β, and the B port 46γ of the OCV 41 to discharge the oil 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 (right side 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 camshaft 14 with respect to the intake timing pulley 17 (crankshaft 4) is changed, the camshaft 14 rotates from the most retarded position to the most advanced position, and the intake valve 12 The valve opening timing of is advanced. Note that the VVT spool 35 is restricted from moving further by being brought into contact with the intake side timing pulley 17, and the intake valve 12 is in a state in which the VVT spool 35 is displaced to the contact position (the most advanced position). The valve opening timing of is the earliest.

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

At the same time, a passage 45γ on the left side of the figure
Communicates with the A port 46β and the reservoir port 46δ, and the hydraulic oil in the advance side pressure chamber 36 is the first hydraulic pressure supply passage 1
4β, the first hydraulic pressure supply hole 16α, the A port 46β of the OCV 41, and the reservoir port 46δ through the oil pan 3
It is discharged to 9. The maximum connection amount between the first hydraulic pressure supply hole 16α and the reservoir port 46δ is 100%.

Therefore, the VVT spool 35 is moved at the maximum speed while rotating to the front end side (the left side in the drawing) by the hydraulic pressure applied to the rear end side, and is reversely directed to the intake side camshaft 14 via the sleeve 31. Is given a twist. As a result, the rotational phase of the intake camshaft 14 with respect to the intake timing pulley 17 (crankshaft 4) is changed, the camshaft 14 rotates from the most advanced position to the most retarded position, and the intake valve 12 The valve opening timing is retarded. The VVT spool 35 is restricted from moving further by being brought into contact with the housing 34 of the pulley 17, and the intake valve 12 is in a state where the VVT spool 35 is displaced to the contact position (the most retarded position). The valve opening timing of is the latest.

As described above, the electromagnetic actuator 42
The stroke of the VVT spool 35 is changed by changing the duty ratio for controlling the VVT spool from 0% to 100%. Therefore, the first and second hydraulic pressure supply holes 16α, 16
Amount of connection between β and tank port 46α, and first and second
The connection amount 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.

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 where it blocks A port 46β and B port 46γ. Therefore, the first and second hydraulic pressure supply holes 16α, 16β and the tank port 46α,
The connection amount between the first and second hydraulic pressure supply holes 16α and 16β and the reservoir port 46δ is 0%, and VV
The T spool 35 is not displaced on 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, the holding duty value GDVT
H is updated by learning in order to remove errors due to component tolerances, deterioration over time, 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, which constitutes the drive control means and the gear position detection means of the embodiment of the present invention, has a CPU (central processing unit) 51 and a ROM (which stores various programs including a "VVT calculation routine" described later) ( It is composed of a read-only memory) 52, a RAM (readable / writable memory) 53 for temporarily storing various information and the like.

Cylinder discrimination sensor 56, crank angle sensor 5
The CPU 5, 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 the external input circuit 54.
1 connected.

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

Next, a program relating to valve timing control in the valve timing control device 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 the target valve timing VTT for driving and controlling 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 idle is off. This S
At 101, it is determined whether or not the accelerator pedal is operated. If the idle signal IDL is "1" instead of "0", it is determined that the accelerator pedal has not been operated, the process proceeds to S106, and the engine speed NE is referred to by referring to the idle-on VTT map shown in FIG. The target displacement angle VTTN during idling is searched based on The idle-time VTT map is a map of valve timings obtained in advance by experiments or the like so that suitable output characteristics can be obtained corresponding to the engine speed NE at each time during idling. And the next S1
In 07, the target displacement angle VTT at the time of idling found
Store N in the RAM 53 as the target valve timing VTT, and exit this routine.

If the idle signal IDL is "0" in S101, it is determined to be "YES", that is, it is determined to be idle off. Next, in S102, the target displacement angle base value VTTB at idle-off is searched based on the engine speed NE and the intake pressure PM by referring to the idle-off VTT map shown in FIG. In this idle-off VTT map, valve timings obtained in advance by experiments or the like are mapped so that suitable output characteristics can be obtained corresponding to the engine speed NE and intake pressure PM at each idle-off time. It is a thing.

This map shows that when the engine speed NE is high and the intake pressure PM is large at full load, the valve overlap amount is reduced to improve torque characteristics and maximize high output. The target displacement angle base value VTTB is set to, the engine speed NE is medium speed, and the intake pressure PM is
At the time of partial load operation of medium level, the target displacement angle base value VTTB is set in order to increase the overlap amount and improve the fuel consumption and the exhaust emission.

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

The gear position determination index NVR is defined by each gear position,
That is, since a substantially constant value is obtained at the shift position of the automatic transmission 64, in this embodiment with three forward gears, 3 is obtained.
A value between the gear position determination index at rd and the gear position determination index at 2nd is set as the determination value α. Therefore, if the gear position determination index NVR is larger than the determination value α, it is determined that the gear position in the current traveling state is 2nd or 1st low speed gear position (low speed gear ratio), and the gear position determination index NVR is the determination value α. If it is smaller than this, it is determined to be a high speed gear position (high speed gear ratio) of 3rd.

In S103, the gear position determination index NV
When it is determined that R is smaller than the determination value α, that is, 3
If it is determined to be the high speed gear position of rd (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 this routine is exited.

On the contrary, 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 to be the 2nd or 1st low speed gear position (low speed gear ratio), the process proceeds to S104 and the low speed is set. With reference to the gear time correction map, the low speed gear time correction value VTTTL is searched based on the engine speed NE and the intake pressure PM.

The correction value VTTLG at low speed gear is set for the following reason. VT at idle off
In the T map, the valve timing is such that the overlap is enlarged so that the fuel economy and the emission are most improved when the shift position of the automatic transmission is at the high gear position when the load is partly loaded. However, if this overlap is expanded to the limit where combustion becomes unstable, drivability will be poor. This drivability failure will occur when the shift position of the automatic transmission is in the low speed gear position rather than the high speed gear position. Easy to experience. Therefore, if the valve timing at the low speed gear position is the same as that at the high speed gear position, the frequency of occurrence of defective drivability will increase, so the valve timing displacement angle will be smaller than at the high speed gear position, and In order to reduce the lap and suppress the occurrence of a poor drivability, this correction value is preliminarily selected by experiments or the like so that the drivability is not deteriorated in the low speed gear position.

Therefore, at the low speed gear position, the target displacement angle base value VT during idle-off at the high speed gear position is set.
A correction value VTTLG for low speed gear is set as a correction value for retarding the valve timing rather than TB.

At S104, the correction value VTT at low speed gear
When the search for LG is completed, the low-speed gear correction value VTTTL is subtracted from the idle-off target displacement angle base value VTTB in S105, the result of this subtraction is stored in the RAM 53 as the target valve timing VTT, and this routine is exited.

When the VTT calculation routine is completed as described above, the CPU 51 executes 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 drive duty value DVT is calculated by the following equation. DVT = GDVTH + K × (VTT-VT) In the above equation, GDVTH is the above-mentioned 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, so that the phase holding control of the VVT 30 at the target valve timing VTT is performed. (A) Now, 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 is such that the overlap is expanded. Corner base value V
TTB is set as the target valve timing VTT. Therefore, in this case, the internal EGR can be increased,
Fuel economy and emissions are improved.

When it is determined in S103 that the low speed gear position (low speed gear ratio) is determined, the low speed gear correction value VTTLG is subtracted from the idle-off target displacement angle base value VTTB at the high speed gear position. The valve timing is delayed from the valve timing at the high speed gear position. As a result, the valve overlap is reduced, the internal EGR is reduced, and the combustion stability is increased, so that the deterioration of drivability can be prevented. (B) In addition, 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 the shift position sensor is not necessary and the software is compatible, the number of parts can be reduced and the cost can be reduced.

The following embodiments can be carried out without departing from the spirit of the present invention. (A) In the above-mentioned embodiment, the intake side valve has V
The VT30 was provided. By changing this, 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, but a throttle opening sensor that detects 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-described embodiment, the determination value α is set to a value between the gear position determination indexes of 3rd and 2nd in an automatic transmission with three forward gears, but the present invention is not limited to this gear stage. In an automatic transmission having a gear mechanism capable of shifting a plurality of gears, the determination value α may be set between the low speed gear position and the high speed gear position. (E) A diesel engine system may be used instead of the gasoline engine system. (H) In the above embodiment, the gear position determination index NVR is calculated and the gear position is detected by comparing this NVR with the determination value α. However, instead of this, the automatic transmission 64 uses the shift position sensor. May be provided to detect the shift position.

The technical idea which can be understood from the above-described embodiment of the 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 the opening / closing timing of at least one of the intake valve and the exhaust valve. By doing this,
In the exhaust valve, it is possible to obtain the same effects as the above-described embodiment. (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 detected by the operating state detecting means and the engine speed. Since the shift position sensor is not required for the speed change means and the shift position sensor is software compatible, 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 during high speed gears, and
Exhaust emission can be improved, and internal E
By reducing the GR, combustion stability can be increased, so that 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 correction map for a low speed gear.

[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 ... retard side pressure chamber, 3
8 ... Oil pump, 41 ... Oil control valve as operating hydraulic pressure adjusting means, 50 ... ECU that constitutes gear position detecting means and drive controlling means, 59 to 62 ... Sensors and switches that constitute operating state detecting means, 61 ... Rotation Number sensor, 64 ... An automatic transmission that constitutes a transmission means.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location F02M 25/07 550 F02M 25/07 550R

Claims (1)

[Claims] 1. A variable valve timing mechanism for changing opening / closing timing of 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 an operation of the internal combustion engine. An operating state detecting means for detecting the state, a drive control means for driving and controlling the variable valve timing mechanism to control the valve overlap amount based on the detection result of the operating state detecting means, and a gear change for changing the gear ratio. Gear position detecting means for detecting the gear position of the means, and the drive control means controls the variable valve timing mechanism so that the internal EGR decreases when the detection result of the gear position detecting means is the low speed gear position. A valve timing control device for an internal combustion engine, comprising: