JPH10121999A - Valve timing control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent combustion from being unstable since the degree of overlap is excessive during idle operation or low load operation and to prevent occurrence of engine stall in such a case that a variable valve timing mechanism falls in trouble so as to be inoperative. SOLUTION: An ECU 70 controls the drive of VVTs 29L, 29R, and determines whether or not the phase angles θ01, θ02, of actual valve timings of the VVTs 29L, 29R fall in a phase angle range based upon desired valve timing angles θT1, θT2 calculated from an engine rotational speed NE, a water cooling temperature THW and the like, and whether or not such a condition is successively determined by a number of repetitions greater than 5. If it is determined by a number of repetitions greater than 5 that the phase angles are out of the phase angle range, the ECU 70 determines that the VVTs 29L, 29R are erroneously operated, and forces the desired valve timing of the VVTs 29L, 29R which are not erroneously operated, to be fixed to a valve timing which has the minimum degree of overlap.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve timing control device for an internal combustion engine having a variable valve timing mechanism capable of adjusting the opening and closing timing of a valve according to the operating state of the internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, as this kind of technology, for example, a technology disclosed in Japanese Patent Application Laid-Open No. 5-98916 is known. According to this technique, in an engine having a plurality of cylinder groups, when the actual valve timing of a variable valve timing mechanism of one cylinder group is determined to be abnormal (hereinafter, referred to as “fail”), the other cylinder group side is determined. The actual valve timing of the variable valve timing mechanism described above is forcibly made to coincide with the actual valve timing of the variable valve timing mechanism determined to have failed.

Accordingly, even if only one of the plurality of variable valve timing mechanisms malfunctions, the valve timings of all the variable valve timing mechanisms are the same. As a result, even if one of the variable valve timing mechanisms malfunctions and does not operate, the torque balance between the cylinder groups is maintained, and an extremely unstable state such as unnecessary vibration or deterioration of exhaust gas characteristics is caused. Can be avoided.

[0004]

However, in the above-mentioned prior art, the state where the variable valve timing mechanism on one cylinder group side has failed is, for example, the position (maximum advance angle) where the amount of overlap becomes maximum. If fixed to
Other variable valve timing mechanisms are also forcibly fixed to the most advanced angle. In such a state, the overlap amount becomes large in all the cylinder groups, and particularly at the time of idling or light load, the exhaust gas from the exhaust port is sucked back into the cylinder due to the negative pressure in the intake pipe, and the residual gas remains. The proportion of gas increases. As a result, combustion becomes unstable, and engine stall is likely to occur.

The present invention has been made in view of the above-mentioned problem, and when the variable valve timing mechanism malfunctions and does not operate, the overlap amount becomes large at the time of idling or light load, and the combustion failure occurs. It is an object of the present invention to provide a variable valve timing control device that prevents the engine from stalling and prevents the engine from stalling.

[0006]

According to a first aspect of the present invention, there is provided a variable valve timing control apparatus for an internal combustion engine, as shown in FIG.
M2, and is provided for each of the cylinder groups M1 and M2, and is used to open and close at least one of the intake valve M4 and the exhaust valve M5 of the cylinder group M1 and the intake valve M of the cylinder group M2.
6 and a plurality of variable valve timing mechanisms M capable of adjusting the opening / closing timing of at least one of the exhaust valves M7
8 and M9, one cylinder group M1
When the variable valve timing mechanism M8 (M9) of (M2) malfunctions, the variable valve timing mechanism M9 (M9) of another cylinder group M2 (M1) that does not malfunction.
The drive control means M10 that enables the valve timing of 8) to be forcibly set to a timing at which the amount of overlap between the intake valve M6 (M4) and the exhaust valve M7 (M5) becomes small is provided. Make a summary.

According to a second aspect of the present invention, there is provided the variable valve timing control apparatus for an internal combustion engine according to the first aspect, wherein: an operating state detecting means for detecting an operating state of the internal combustion engine; A plurality of actual timing detection means provided for each of the variable valve timing mechanisms M8 and M9 for detecting actual valve timings of the valves M4 to M7 adjusted by the variable valve timing mechanisms M8 and M9; Target timing calculating means for calculating target valve timings of the variable valve timing mechanisms M8 and M9 according to the operating state of the internal combustion engine detected by the operating state detecting means;
Each of the variable valve timing mechanisms M is based on a deviation between the target valve timing by the target timing calculation means and each actual valve timing by the actual timing means.
An operation failure detecting means for detecting an operation failure for each of M8 and M9;
When the operation failure detecting means detects the operation failure of the variable valve timing mechanism M8 (M9), the operation failure is detected according to the valve timing of the variable valve timing mechanism M8 (M9) that has caused the operation failure. The gist of the invention is to provide an overlap amount setting means for enabling the target valve timing of the variable valve timing mechanism M9 (M8) to be forcibly set to a timing at which the overlap amount becomes small.

According to a third aspect of the present invention, in the variable valve timing control apparatus for an internal combustion engine according to the second aspect, the overlap amount setting means is configured to detect the operation failure by the operation failure detecting means. When the operation failure of the variable valve timing mechanism M8 (M9) is detected, the target valve timing of the variable valve timing mechanism M9 (M8) in which the malfunction is not detected is forcibly set to the timing at which the overlap amount is minimized. The main point is to set.

(Operation) According to the variable valve timing control device for an internal combustion engine according to the first aspect, as shown in FIG. 1, when the internal combustion engine M3 is operating, one variable valve timing mechanism M8 (M9) is operated. When an operation failure is detected, another variable valve timing mechanism M9 (M8) that does not cause the operation failure according to the state of the valve timing of the valve by the variable valve timing mechanism M8 (M9) in which the operation failure is detected. Target valve timing of the intake valve M6 (M4) and the exhaust valve M7
Forcibly set at the timing when the amount of overlap with (M5) becomes small.

Therefore, for example, one of the plurality of variable valve timing mechanisms M8 and M9 has an operation failure and stops operating, and the valves M4 and M9 are not operated.
When the valve timing of No. 5 is fixed, the valve timing of M6 and M7 by the other variable valve timing mechanism M9 is set to a timing at which the maximum overlap amount becomes small.

According to the variable valve timing control apparatus for an internal combustion engine according to the second aspect, the operating state detecting means detects the operating state of the internal combustion engine M3. Also,
The valves M4 to M4 adjusted by the variable valve timing mechanisms M8 and M9 by the actual timing detecting means.
The actual valve timing of M7 is detected. Then, the target valve timing of the valves M4 to M7 by the variable valve timing mechanisms M8 and M9 is calculated by the target timing calculation means as the drive control means M10 according to the operation state detected by the operation state detection means. . In addition, the variable valve is detected based on a deviation between the target valve timing calculated by the target timing calculating means and the actual valve timing detected by the actual valve timing detecting means. The operation state of the timing mechanisms M8 and M9 is detected. When the operation failure of the variable valve timing mechanism M8 (M9) is detected by the operation failure detection means, the defective operation by the target timing calculation means is detected by the overlap amount setting means as the drive control means M10. The target valve timing of the variable valve timing mechanism M9 (M8) is set forcibly to a timing at which the overlap amount becomes small.

According to the valve timing control apparatus for an internal combustion engine, when one of the variable valve timing mechanisms M8 (M9) malfunctions, another variable valve timing that does not malfunction is generated. Mechanism M9 (M8)
Is forcibly set to a timing at which the overlap amount is minimized.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) Hereinafter, a first embodiment in which the variable valve timing control device according to the present invention is embodied in a V-type engine will be described in detail with reference to FIGS. Note that V
The internal configurations of a left bank as a first cylinder group and a right bank as a second cylinder group that constitute a type engine are as follows.
Since it is basically plane-symmetric, only the left bank will be described here, and the description of the right bank will be omitted.

FIG. 2 is a schematic configuration diagram showing a variable valve timing control device for an internal combustion engine according to this embodiment.
The engine 1 as an internal combustion engine having a plurality of cylinders has a cylinder block 2 provided with a cylinder bore 2a for each cylinder, and a piston 3 is provided in each cylinder bore 2a so as to be vertically movable. The combustion chamber 4 is located above the piston 3 in the cylinder bore 2a. Each combustion chamber 4 is provided with a spark plug 5. Further, each combustion chamber 4 is provided with an intake passage 6 and an exhaust passage 7 which communicate with each other through an intake port 6a and an exhaust port 7a. The intake port 6a and the exhaust port 7a are provided with an intake valve 8 and an exhaust valve 9 for opening and closing, respectively. These intake valve 8 and exhaust valve 9
Are the intake camshaft 10 and the exhaust camshaft 11
Driven by the rotation of. Also, each camshaft 10,
At one end of 11, an intake-side timing pulley 12 and an exhaust-side timing pulley 13 are provided. Further, each of the timing pulleys 12 and 13 is drivingly connected to a crankshaft (not shown) via a timing belt 14.

Therefore, during operation of the engine 1, rotational power is transmitted from the crankshaft to the respective camshafts 10, 11 via the timing belt 14 and the respective timing pulleys 12, 13, and the rotation of the respective camshafts 10, 11 causes intake air to be taken. The valve 8 and the exhaust valve 9 are driven to open and close. The opening and closing timings of the intake valve 8 and the exhaust valve 9 are synchronized with the rotation of the crankshaft, 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. It is designed to be opened and closed at the timing.

An air cleaner 15 is provided on the inlet side of the intake passage 6.
The fuel injectors 16 are provided in the vicinity of the intake ports 6a of the respective cylinders. Then, the engine 1 takes in outside air from the air cleaner 15 through the intake passage 6. At the same time as taking in the outside air, the engine 1 takes in the fuel injected from each injector 16. Then, the engine 1 introduces the mixture of the taken fuel and the outside air into the combustion chamber 4 in synchronization with the opening of the intake valve 8 in the intake stroke. The engine 1 explodes and burns the air-fuel mixture introduced into the combustion chamber 4 by igniting a spark plug 5 to obtain a driving force, and then exhausts the exhaust gas in synchronization with the opening of an exhaust valve 9 in an exhaust stroke. Port 7a
And discharged to the outside through the exhaust passage 7.

In the middle of the intake passage 6, there is provided a throttle valve 17 which is opened and closed in conjunction with operation of an accelerator pedal (not shown). When the throttle valve 17 is opened and closed, the amount of intake air, which is the amount of outside air taken into the intake passage 6, is adjusted. Further, a surge tank 18 for smoothing the pulsation of the intake air is provided downstream of the throttle valve 17. An intake air temperature sensor 61 for detecting the intake air temperature is provided near the air cleaner 15 in the intake passage 6.

In the vicinity of the throttle valve 17, a throttle sensor 62 for detecting the throttle opening is provided. Further, the surge tank 18 is provided with an intake pressure sensor 63 which communicates with the tank 18 and detects an intake air pressure (intake pressure).

On the other hand, a catalyst converter 20 including a three-way catalyst 19 for purifying exhaust gas is provided in the middle of the exhaust passage 7. An oxygen sensor 64 for detecting the concentration of oxygen in the exhaust gas is provided in the exhaust passage 7. Also, the temperature of the cooling water is
(Cooling water temperature) A water temperature sensor 65 for detecting THW is provided.

An ignition signal distributed by a distributor 21 is applied to each ignition plug 5 for each cylinder.
The distributor 21 distributes the high voltage output from the igniter 22 to each ignition plug 5 in synchronization with the rotation of the crankshaft, that is, the crank angle. The ignition timing of each ignition plug 5 is determined by the high voltage output timing from the igniter 22.

The distributor 21 has a built-in rotor (not shown) which is connected to the exhaust camshaft 11 and rotated in conjunction with the rotation of the crankshaft.
The distributor 21 is provided with a rotation speed sensor 66 for detecting the rotation speed NE of the engine 1 (engine rotation speed) NE from the rotation of the rotor. Further, a cylinder discrimination sensor 67 for detecting a crank angle reference signal GP of the engine 1 at a predetermined rate in accordance with the rotation of the rotor is attached to the distributor 21. In this embodiment, assuming that the crankshaft makes two revolutions in a series of four strokes of an intake stroke, a compression stroke, an explosion / expansion stroke, and an exhaust stroke, the rotation speed sensor 66 outputs the crankshaft at a rate of 30 ° CA per pulse. Detect corners. or,
The cylinder discriminating sensor 67 detects the crank angle at a rate of 360 ° CA per pulse.

In addition, in this embodiment, a throttle valve 17 is provided in the intake passage 6 on the upstream side of the intake valve 8.
A bypass passage 23 is provided to bypass the valve 17 and communicate the upstream side and the downstream side of the valve 17. In the middle of the bypass passage 23, a linear solenoid type idle speed control valve that is driven to adjust the amount of intake air in order to stabilize the idling operation during idling of the engine 1 when the throttle valve 17 is fully closed. (ISCV) 24 is provided. As we all know,
The ISCV 24 has a valve shaft extending through an electromagnetic coil (not shown) therein. And IS
In the CV 24, the size of the gap, that is, the opening degree, which changes the magnetic force of the electromagnetic coil in response to a predetermined control signal and moves the valve shaft back and forth and communicates with the bypass passage 23, can be changed.

Therefore, when the engine 1 is idling,
By controlling the opening of the ISCV 24 and the valve opening time, the amount of air flowing through the bypass passage 23 is adjusted, and the supply of the amount of intake air to the combustion chamber 4 is controlled.

Further, in this embodiment, the exhaust passage 7
A well-known exhaust gas recirculation device (EGR device) 25 for recirculating a part of the exhaust gas in the exhaust passage 7 to the intake passage 6 is provided between the exhaust passage 7 and the intake passage 6. That is,
The EGR device 25 includes an EGR pipe 26 whose both ends are connected to and connected to the exhaust passage 7 and the intake passage 6. EG
An EG for adjusting the flow rate of the exhaust gas is provided in the middle of the R line 26.
An R valve 27 is provided. The EGR valve 27 is driven to open and close by the control of a vacuum switching valve (VSV) 28.

In addition, in this embodiment, a variable valve timing mechanism (hereinafter simply referred to as “VVT”) 29L driven by oil pressure to make the opening / closing timing of the intake valve 8 variable is provided on the intake-side timing pulley 12. Is provided.

Next, the configuration of the VVT 29L and the like will be described in detail with reference to FIG. The camshaft 10 has a cam journal 10a which is the cylinder head 1 of the engine 1.
a and the bearing cap 1b so as to be rotatable. A VVT 29 </ b> L provided integrally with the timing pulley 12 is provided at one end of the camshaft 10.

The timing pulley 12 has a plurality of external teeth 31 on the outer circumference and a receiving recess 32 on one side. Also, the camshaft 1 is covered so as to cover the accommodation recess 32.
A cap 33 is fastened and fixed to the leading end of the bolt 0 by a bolt 34. Further, between the opening end of the timing pulley 12 and the outer periphery of the cap 33, a well-known buffering structure including an outer plate 35 press-fitted and fixed to the pulley 12 and an inner plate 36 formed on the cap 33. A viscous coupling (a viscous coupling) 37 is provided.

A ring gear 38 is interposed between the timing pulley 12 and the camshaft 10 so that
10 are connected. That is, the ring gear 38 is accommodated in the accommodating recess 32 of the timing pulley 12 hermetically sealed by the cap 33. The ring gear 38 has a plurality of teeth 38a and 38b provided on the inner and outer circumferences thereof, both of which are helical teeth, and is rotatable relative to the camshaft 10 by moving in the axial direction. The teeth 38a and 38b on the inner and outer circumferences of the ring gear 38 are
The second outer teeth 12a and the inner teeth 33a of the cap 33 are meshed with each other. The timing pulley 12 is drivingly connected to a crankshaft (not shown) via a timing belt 14 wrapped around the external teeth 31.

Accordingly, when the rotation of the crankshaft is transmitted to the timing pulley 12 via the timing belt 14, the timing pulley 12 and the cap 33 connected by the ring gear 38 are rotated integrally, and the camshaft is rotated. 10 is driven to rotate. At this time, when the ring gear 38 is moved in the axial direction (the left-right direction in FIG. 3), the timing pulley 12
Torsion is given. As a result, the relative phase in the rotation direction between the camshaft 10 and the timing pulley 12 is changed, and the opening / closing timing of the intake valve 8 is changed. The rattling caused by the backlash of the ring gear 38 when the camshaft 10 is twisted is buffered by the action of the viscous coupling 37 so that generation of abnormal noise is suppressed.

In order to drive the ring gear 38 by hydraulic pressure, the housing recess 32 of the timing pulley 12
One end of the ring gear 38 in the axial direction is a pressurizing chamber 39 for introducing hydraulic pressure by hydraulic oil. Similarly, in the housing recess 32, the other end of the ring gear 38 is a spring chamber 41 for housing a balancing spring 40 that opposes the oil pressure. Further, a head oil passage 42 and a shaft oil passage 43 communicating with each other are formed in the cylinder head 1a and the camshaft 10 of the engine 1 in order to supply hydraulic oil to the pressurizing chamber 39. .

On the other hand, in order to drain the hydraulic oil from the pressurizing chamber 39, the timing pulley 12 and a part of the camshaft 10 return the hydraulic oil leaking from the pressurizing chamber 39 to the spring chamber 41. An oil passage 44 is formed.
Also, the timing pulley 1 communicates with the return oil passage 44.
2, a camshaft 10 and a cylinder head 1
a, an oil recovery chamber 46 surrounded by a bearing cap 1b and a rubber seal 45 is provided. Furthermore,
At the lower position of the camshaft 10, the cylinder head 1a
Is formed with an oil return hole 48 for returning the hydraulic oil recovered in the oil recovery chamber 46 to the oil pan 47 of the engine 1.

The upper side of the cylinder head 1a is covered by a head cover 49. Also, cylinder head 1
The head oil passage 50 for supplying lubricating oil to the cam journal 10a is formed in a.

In this embodiment, the lubricating oil of the engine is used as the working oil. That is, the oil pump 51 constituting one system of hydraulic circuit for lubricating oil
The lubricating oil stored in the oil pan 47 is sucked up through the oil filter 52. A main oil passage 54 is connected between the oil pump 51 and the head oil passage 42.
Is provided with a solenoid-type three-type control valve 53L. This control valve 53L is duty-controlled. That is, in the control valve 53L, within a certain range of the duty ratio DUTY as the input command value, the hydraulic pressure as the output with respect to the duty ratio DUTY is proportional. That is, within a certain range of the duty ratio DUTY, the hydraulic pressure increases as the duty ratio increases. Then, as the hydraulic pressure controlled by the control valve 53L increases, the rotational phase of the camshaft 10 is advanced.

Accordingly, during the operation of the oil pump 51, the control valve 53L is duty-controlled to open and close in a predetermined manner, so that the lubricating oil discharged from the oil pump 51 is supplied to the main oil passage 54 with a certain hydraulic pressure as working oil. The oil is supplied to the head oil passage 42 via the head. The hydraulic oil supplied to the head oil passage 42 further passes through the shaft oil passage 43 to the pressurizing chamber 39.
Introduced to. Then, the ring gear 38 is pressed in one of the axial directions (rightward in the drawing) against the urging force of the spring 40 by the hydraulic pressure of the hydraulic oil. Thereby, torsion is given to the camshaft 10 and the rotation phase of the camshaft 10 with respect to the timing pulley 12 is changed.
As a result, the opening / closing timing of the intake valve 8 is changed,
The valve overlap amount between the intake valve 8 and the exhaust valve 9 is changed.

On the other hand, when the input command value is turned off (duty ratio D = 0), the control valve 53L is closed to shut off the supply of the operating oil to the head oil passage 42. As a result, the oil pressure is released from the pressurizing chamber 39, and the ring gear 38
Is pressed by the urging force of the spring 40 toward the other axial direction (to the left in the drawing) and returned. Thereby, the reverse twist is given to the camshaft 10 and the camshaft 10
Is changed. As a result, the opening / closing timing of the intake valve is changed, and the valve overlap amount is changed. At this time, the hydraulic oil leaked from the pressurizing chamber 39 to the spring 40 side passes through the return oil passage 44 to the oil collecting chamber 4.
6 through the oil pan 4 through the oil return hole 48.
It is returned to 7.

As shown in FIG. 2, in this embodiment, operating state detecting means for detecting the operating state of the engine 1 by the above-described sensors 61 to 67 and the like is configured. In addition, in this embodiment, a cam angle sensor that detects the rotation of the camshaft 10 at a predetermined angle interval and outputs it as a cam angle reference signal CBS1 is provided at the base end of the camshaft 10 on the intake valve 8 side. 68L are provided. Similarly, a cam angle sensor 68R that outputs a cam angle reference signal CBS2 is provided in the right bank. The cam angle sensors 68L and 68R are composed of a timing rotor that rotates in conjunction with the rotation of the camshaft 2 and a pickup coil (neither is shown). The cam angle sensors 68L and 68R constitute actual timing detection means.

The injectors 16, igniter 22, ISCV 24, VSV 28 and control valve 53L are electrically connected to an electronic control unit (hereinafter simply referred to as "ECU") 70, and their operation timing is controlled by the operation of the ECU 70. Is done. The ECU 70 constitutes a target timing calculating means, a malfunction detecting means and an overlap amount fixing means. The ECU 70 includes an intake air temperature sensor 61, a throttle sensor 62, an intake pressure sensor 63, an oxygen sensor 64, a water temperature sensor 65, a rotational speed sensor 66, a cylinder discriminating sensor 67, and cam angle sensors 68L and 6L.
8R are respectively connected. The ECU 70 controls each of the sensors 6 to control the fuel injection amount of the engine 1, the ignition timing control, the idle speed control, the EGR control, and the like.
1 to 68L, 68R, each injector 16, igniter 22, ISCV 24 and VSV
28 is suitably controlled. At the same time, the ECU 70 controls the valve timing,
Throttle sensor 62, water temperature sensor 65, rotation speed sensor 66, cylinder discrimination sensor 67, and cam angle sensors 68L, 6
Based on output signals from the 8R and the like, the valve overlap amount is determined according to the operating state of the engine 1 at each time, and the drive of the control valves 53L and 53R is suitably controlled. At the same time, the ECU 70 controls the various sensors 6 described above.
VVT29 based on the detection results of 1-68L, 68R, etc.
The abnormality of L, 29R is determined. In this embodiment, the ECU 70 includes VVT 29L, 68R
When an abnormality is determined, a diagnostic lamp 30 that is turned on to notify the driver or the like of the abnormality is connected.

Next, the electrical configuration of the ECU 70 will be described with reference to the block diagram of FIG. The ECU 70 includes a central processing unit (CPU) 71, a read-only memory (ROM) 72 in which a predetermined control program and the like are stored in advance, a CP
A random access memory (RAM) 73 for temporarily storing the operation result of U71, a backup RAM 74 for storing previously stored data, and the like, and these units, an external input circuit 75, an external output circuit 76, and the like are connected by a bus 77. It is configured as a theoretical operation circuit.

The external input circuit 75 includes an intake air temperature sensor 61, a throttle sensor 62, an intake pressure sensor 63,
Oxygen sensor 64, water temperature sensor 65, rotation speed sensor 66,
The cylinder discrimination sensor 67 and the cam angle sensors 68L and 68R are connected respectively.

On the other hand, the external output circuit 76 includes each injector 16, igniter 22, ISCV 24, VSV2
8, the diagnostic lamp 30 and the control valves 53L, 53R are connected respectively.

Then, the CPU 71 reads, as input values, detection signals from the sensors 61 to 68L, 68R, etc., which are input via the external input circuit 75. In addition, the CPU 71 determines each injector 16, igniter 22, ISC based on the input values read from the sensors 61 to 68L, 68R.
V24, VSV28, diagnostic lamp 30, and control valve 5
3L and 53R are suitably controlled.

Next, a processing operation for valve timing control executed by the above-described ECU 70 will be described with reference to FIG.
And FIG. 5 and 6 show a valve timing control routine for changing the opening / closing timing of the intake valve 6 of the left bank and the opening / closing timing of the intake valve of the right bank (not shown) among the processes executed by the ECU 70. Also, in this flowchart, V provided in the left bank (right bank)
VV when malfunction is detected in VT29L (29R)
A fixing control process for fixing the maximum overlap amount of T29R (29L) is included. This routine is executed by a periodic interruption every predetermined time while the engine 1 is operating.

When the process proceeds to this routine, first, in step (hereinafter referred to as S) 101, the flag F1 indicating the operating state of the VVT 29L provided in the left bank is set to "0" or "1". Is determined. At this time, if the flag F1 is “1”, it is determined that an operation failure has occurred in the VVT 29L, and the process shifts to S102.
If it is determined in S101 that a malfunction has occurred in the VVT 29L, then in S102, the phase angle θT2 of the target valve timing of the VVT 29R provided in the right bank (hereinafter referred to as the target phase angle) θT2 is set to the overlap amount. Phase angle (most retarded angle) θ at which valve timing is minimized
It is fixed to min, and the routine goes to S118. Also, the flag F1
Is “0”, the process proceeds to S103 assuming that the VVT 29L is operating normally.

Next, in S103, similarly to S101, the flag F2 indicating the operation state of the VVT 29R is set to
It is determined whether it is “0” or “1”. At this time,
If the flag F2 is "1", it is determined that an operation failure has occurred in the VVT 29R, and the flow shifts to S104. And
If it is determined in S101 that a malfunction has occurred in the VVT 29R, then in S104, as in S102,
The target phase angle θT1 of the VVT 29L is changed from the phase angle (most retarded angle) θmin of the valve timing at which the overlap amount becomes minimum.
And the process proceeds to S118. If the flag F2 is "0", the process proceeds to S105 assuming that the VVT 29R is operating normally.

That is, in S101 and S103, when both the flags F1 and F2 are "0" (normal operation),
Move to 105. The flags F1 and F2 are initially set to “0”.

Subsequently, at S105, the water temperature sensor 6
5, based on the rotation speed sensor 66 and the cylinder discrimination sensor 67,
Each detected value such as the engine speed NE, the coolant temperature THW, and the crank angle reference signal GP is read. In the following S106, the read engine speed NE and cooling water temperature T are read.
VVT29 based on the HW, crank angle reference signal GP, etc.
The target phase angle θT1 of L is calculated.

Next, in S107, the actual valve timing θ01 of the left bank detected by the detection signal of the cam angle sensor 68L of the left bank is read. In S108, the target phase angle θT1 of the VVT 29L calculated in S106
On the other hand, the phase angle of the actual valve timing of the left bank read in S107 (hereinafter referred to as the actual phase angle) θ01 is ± 3 °.
(Here, ± 3 ° is a permissible error set in advance in the present embodiment, and this numerical value may be changed as appropriate).

As a result, if the actual phase angle θ01 satisfies the above condition, it is determined that there is no possibility of a malfunction of the VVT 29L, and the flow shifts to S109. At S109, the counter C1 (the left bank of the left bank in this routine) is determined. The counter C1 for storing the number of control processes is cleared, and the value of the counter C1 is set to "0". Then, the process proceeds to S110. If the actual phase angle θ01 does not satisfy the above condition, VVT2
It is determined that there is a possibility of a 9L operation failure, and the process proceeds to S110 with the value of the counter C1 unchanged.

At S110, the actual phase angle θ02 of the right bank is read based on the detection signal of the cam angle sensor 68R of the right bank, as in S107. Then, in S111, similarly to S108, the VVT calculated in S106.
With respect to the target phase angle θT2 of 29R, it is determined whether or not the actual phase angle θ02 of the right bank read in S110 is within the range of ± 3 °.

As a result, if the actual phase angle θ02 satisfies the above condition, it is determined that there is no possibility of an operation failure of the VVT 29R, and the flow shifts to S112. At S112, the counter C2 (the right bank in the present routine) is executed. The counter for storing the number of times of processing is cleared, and the value of the counter C2 is set to “0”. Then, the process proceeds to S113. If the actual phase angle θ02 does not satisfy the above condition, VVT2
Since it is determined that there is a possibility of a 9R operation failure, the process proceeds to S113 with the value of the counter C2 as it is.

In S113, the phase angle of the valve timing of the left bank is set to the target phase angle θ calculated in S106.
A change amount ΔD1 of the duty ratio required for controlling to T1
And a duty ratio change amount ΔD2 required to control the phase angle of the valve timing of the right bank to the target phase angle θT2 calculated in S106. The change amount ΔD1 of the duty ratio is obtained by subtracting the duty ratio corresponding to the actual phase angle θ01 from the duty ratio corresponding to the target phase angle θT1, as shown in FIG. Similarly, the change amount ΔD2 of the duty ratio is obtained by a difference obtained by subtracting the duty ratio corresponding to the actual phase angle θ02 from the duty ratio corresponding to the target phase angle θT2. Note that FIG.
4 is a graph showing a relationship between a valve timing phase angle and a duty ratio in the device of the embodiment.

At S114, the target duty ratio Di1 of the control valve 53L is calculated by adding ΔD1 calculated at S113 to the previous target duty ratio Di1-1 of the control valve 53L. In subsequent S115,
Similarly to S114, the target duty ratio Di2 of the control valve 53R is calculated by adding ΔD2 calculated in S113 to the previous target duty ratio Di2-1 of the control valve 53R.

Subsequently, in S116, the counter C1
Is incremented, and in S117, the counter C2
Is incremented. In steps S116 and S117, the number of times the left bank and the right bank are processed in this routine is counted.

Thereafter, in S118, each control valve 5 is controlled based on the duty ratios corresponding to the target phase angles θT1 and θT2.
3L and 53R are controlled, and the processing in this routine is temporarily terminated.

On the other hand, in the ECU 70, a processing operation for detecting a malfunction of the VVTs 29L and 29R is performed in parallel with the above processing routine. Next, the processing operation for detecting the operation failure will be described with reference to FIG.

FIG. 8 is a flowchart showing a malfunction detection routine for detecting a malfunction of the VVTs 29L and 29R among the processes executed by the ECU 70. This routine is also executed by a periodic interruption every predetermined time while the engine 1 is operating.

When the processing shifts to this routine, first, S
At 121, the actual phase angle θ01 of the left bank is VVT2
It is determined whether or not the target phase angle θT1 of 9L is within the range of ± 10 ° (here, ± 10 ° is a criterion set in advance in the present embodiment, and this numerical value is appropriately changed. May be used). As a result, if the actual phase angle θ01 satisfies the above condition, it is determined that there is no possibility of a malfunction of the VVT 29L, and the process shifts to S124. If the actual phase angle θ01 does not satisfy the above condition, VVT29
It is determined that there is a possibility that the operation of L is defective, and the flow shifts to S122. In S122, it is determined whether the value of the counter C1 is less than “5”. That is, if the state where the actual phase angle θ01 is out of the allowable range continues in the determination result of S108 in the valve timing control routine (FIGS. 5 and 6), the value of the counter C1 becomes “5” or more in S116. Become. Therefore, at this time, if the value of the counter C1 is less than “5”, it is determined that no operation failure has occurred in the VVT 29L, and the process shifts to S124. Also,
If the value of the counter C1 is not less than “5” (the counter C
If the value of 1 is “5” or more), it is determined that an operation failure has occurred in the VVT 29L, and the flow shifts to S123. S
123, the VVT29L provided in the left bank
Is set to "1".

Next, in S124, similarly to S121, it is determined whether the actual phase angle θ02 of the right bank is within ± 10 ° of the target phase angle θT2 of the VVT 29R (here, ± 10 °). Is a criterion set in advance in the present embodiment, and this numerical value may be appropriately changed. As a result, if the actual phase angle θ02 satisfies the above condition, it is determined that there is no possibility of an operation failure of the VVT 29R, and the processing in this routine is temporarily terminated. If the actual phase angle θ02 does not satisfy the above condition, VVT29
It is determined that there is a possibility of a malfunction of R, and the flow shifts to S125.

In S125, similar to S122,
It is determined whether the value of the counter C2 in the right bank is less than “5”. At this time, if the value of the counter C2 is less than "5", it is determined that no operation failure has occurred in the VVT 29R, and the processing in this routine is temporarily terminated, as described above. If the value of the counter C2 is not less than “5” (if the value of the counter C2 is “5” or more), VVT2
It is determined that a malfunction has occurred in 9R, and the flow shifts to S126. In S126, the flag F2 indicating the operating state of the VVT 29R provided in the right bank is set to "1", and the processing in this routine is temporarily ended. Note that S
The value “5” in 122 and S125 is a criterion set in advance in the present embodiment, and this numerical value may be appropriately changed.

As described above, the ECU 70 performs valve timing control and operation failure detection by repeatedly performing each of these processes (routines). In other words, the malfunction detection routine is performed based on the processing result of the valve timing control routine, and the valve timing control routine is performed based on the processing result of the malfunction detection routine. When an operation failure is detected by each of the above processes,
The ECU 70 turns on the diagnosis lamp 30.

Subsequently, the operation and effect of the variable valve timing control device controlled as described above will be described below. (A) When one of the VVTs 29L (29R) malfunctions, the valve timing of the other normally functioning VVT 29R (29L) is forcibly fixed to the valve timing that minimizes the valve overlap amount. . Therefore, even if the phase angle of the valve timing of one of the VVTs 29L (29R) in which the operation failure occurs is fixed to the phase angle at which the valve overlap amount becomes the maximum, the other VVT29R (29L) in which the operation is normal has the following problem. The phase angle of the valve timing is fixed to a phase angle at which the valve overlap amount is minimized. For this reason, the normal operation VV
When the malfunction also occurs in the T29R (29L), the phase angle of the valve timing is prevented from being fixed to the phase angle that maximizes the valve overlap amount. Therefore,
It is possible to maintain combustion stability during idling or when the load is small, and it is possible to reliably prevent engine stall.

(B) In the malfunction detection routine, the VVTs 29L, 29R have the actual phase angles θ01, θ02 outside the range of ± 10 ° of the target phase angles θT1, θT2, and the values of the counters C1, C2 are “ 5 ”or more (only when the actual phase angles θ01 and θ02 are out of the range of ± 3 ° of the target phase angles θT1 and θT2 five or more times consecutively in the valve timing control routine) It is determined that a defect has occurred. Therefore, V
It is possible to prevent erroneous detection of malfunction of the VTs 29L and 29R.

(C) When it is determined that some abnormality has occurred in the VVT 29, the diagnostic lamp 30 is turned on. For this reason, the abnormality can be promptly notified to the driver or the like.

(Second Embodiment) At the target phase angles θT1 and θT2 of the VVTs 29L and 29R, an upper limit phase angle θmax for limiting the phase angle at which the amount of overlap is maximized is set in advance. When one of the VVTs 29L (29R) malfunctions, the other VVT 29R (2R) having a normal operation operates.
The drive control of the VVT 29R (29L) may be performed within a range where the target phase angle θT2 (θT1) of 9L) does not exceed the upper limit phase angle θmax.

A second embodiment of the variable valve timing control device thus embodied will be described with reference to FIG.
The second embodiment is different from the first embodiment only in a part of the processing in the valve timing control routine. Therefore, the same processes as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

FIG. 9 is a part of a flowchart showing the difference between the processing of the valve timing control routine of the first embodiment and the valve timing control routine of the second embodiment. Note that connectors “1” and “2” in FIG. 9 continue to connectors “1” and “2” in FIG.

According to this flowchart, first, at S10
5, the processing of S106 is performed, and then S101, S10
Step 2 is performed. In S101, if the flag F1 is "1", the flow shifts to S131, and the flag F1
If is “0”, the process proceeds to S103.

In S131, it is determined whether or not the target phase angle θT2 of the VVT 29R exceeds a preset upper limit phase angle θmax. As a result, if the target phase angle θT2 of the VVT 29R exceeds the upper limit phase angle θmax, the flow shifts to S132. Then, in S132, the target phase angle θT2 of the VVT 29R is fixed to the preset upper limit phase angle θmax, and the flow shifts to S118. If the target phase angle θT2 of the VVT 29R does not exceed the upper limit phase angle θmax, the process proceeds to S118.

Next, in S103, if the flag F2 is "1", the flow proceeds to S133, and if the flag F2 is "0", the flow proceeds to S107. In S133, it is determined whether or not the target phase angle θT1 of the VVT 29L exceeds a preset upper limit phase angle θmax. as a result,
If the target phase angle θT1 of the VVT 29L exceeds the upper limit phase angle θmax, the flow shifts to S134. Then, in S134, the target phase angle θT1 of the VVT 29L is fixed to the preset upper limit phase angle θmax, and the flow shifts to S118. The target phase angle θT1 of the VVT 29L is equal to the upper limit phase angle θmax.
If it does not exceed, the process proceeds directly to S118.

Therefore, when one of the VVTs 29L (29R) malfunctions, the other VVT 29 having a normal operation operates.
The valve timing of R (29L) is controlled within a range equal to or less than a preset upper limit valve timing. Therefore, if the upper limit valve timing is set to such an extent that the combustion stability can be maintained at the time of idling or when the load is small, the unstable combustion occurs even when both VVTs 29L and 29R malfunction. Can be prevented.

It should be noted that the present invention is not limited to the above-described embodiment, and a part of the configuration can be appropriately changed without departing from the spirit of the invention, and the present invention can be implemented as follows. (1) In each of the embodiments, the valve timing control of the left bank and the right bank is performed in the same routine.
Although the malfunction detection of the left bank and the right bank is performed in the same routine, the valve timing control and the malfunction detection of the left bank and the right bank may be performed in different routines.

(2) In the first embodiment, the VVT 29
When one of L and 29R malfunctions, the target valve timings .theta.T1 and .theta.T2 of the other VVTs 29L and 29R whose operation is normal are forcibly fixed to the valve timing .theta.min at which the amount of overlap is minimized. . This is achieved by providing means for detecting the fixed position of the valve timing of one of the VVTs 29L and 29R that has malfunctioned, and the fixed position of the valve timing of the one of the VVTs 29L and 29R that has malfunctioned to achieve combustion stability. Is in the fixed position of the valve timing that allows
The VTs 29L and 29R are independently and variably controlled as they are. By doing so, engine stall can be prevented and power reduction can be minimized. This may be embodied in the second embodiment. In this case, the variable control is performed as usual, ignoring the setting of the upper limit phase angle θmax.

(3) In each of the above embodiments, the operation failure of the VVTs 29L and 29R is determined by comparing the phase angle between the target valve timing and the actual valve timing. Angle) and the target retard (advance) speed, and VVT29L, 2
The operation failure of the VVTs 29L and 29R may be determined by comparing the actual retard (advance) time of 9R and the target retard (advance) time.

(4) In each of the above-described embodiments, the case where the abnormality of the VVT 29 whose drive is switched by hydraulic control is determined is specified. However, the present invention is not limited to this. It can also be embodied when judging the abnormality of another type of VVT.

(5) In each of the above embodiments, the present invention is embodied as a ring gear type VVT, but may be embodied as a vane type VVT. (6) In each of the above embodiments, the VVT 29 that changes only the opening / closing timing of the intake valve 8 is provided. However, the VVT that changes the opening / closing timing of the exhaust valve 9 and the opening / closing of both the intake valve 8 and the exhaust valve 9 are provided. A VVT with variable timing may be provided.

(7) In each of the above embodiments, the control device of the VVT 29 is embodied as a V-type engine, but may be embodied as another type of engine. (8) In the above embodiments, the diagnosis lamp 30 is turned on when it is determined that the VVT 29 is abnormal. However, such a lighting process may be omitted.

(9) In each of the above embodiments, the bypass passage 23, the ISCV 24, and the EGR device 25 are provided, but one or both of them may be omitted.

[0078]

As described above in detail, according to the present invention, there are provided a plurality of variable valve timing mechanisms capable of adjusting the valve opening / closing timing in accordance with the operating state of an internal combustion engine having a plurality of cylinder groups. In the variable valve timing control device, when the variable valve timing mechanism malfunctions and stops operating, prevent the engine from stalling by preventing the overlap amount from becoming large and causing unstable combustion at idle or light load. An excellent effect is achieved.

[Brief description of the drawings]

FIG. 1 is a conceptual configuration diagram illustrating a basic conceptual configuration of the present invention.

FIG. 2 is a schematic configuration diagram showing a variable valve timing control device according to an embodiment of the present invention;

FIG. 3 is a sectional view showing a configuration of a VVT or the like in the first embodiment.

FIG. 4 is a block diagram showing a configuration of an ECU and the like in the first embodiment.

FIG. 5 is a flowchart illustrating a “valve timing control routine” executed by the ECU in the first embodiment.

FIG. 6 is a flowchart following FIG. 5;

FIG. 7 is a graph showing a relationship between a phase angle of a valve timing and a duty ratio in the first embodiment.

FIG. 8 is a flowchart illustrating an “operation failure detection routine” executed by the ECU in the first embodiment.

FIG. 9 is a flowchart illustrating a “valve timing control routine” executed by the ECU in the second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine as an internal combustion engine, 4 ... Combustion chamber, 6 ... Intake passage, 7 ... Exhaust passage, 8 ... Intake valve, 9 ... Exhaust valve, 29L, 29R ... Variable valve timing mechanism (VV
T), 61: intake air temperature sensor, 62: throttle sensor,
63: intake pressure sensor, 64: oxygen sensor, 65: water temperature sensor, 66: rotation speed sensor, 67: cylinder discrimination sensor, 6
8L, 68R: cam angle sensor; 70: ECU.

Claims (3)

[Claims] An internal combustion engine having a plurality of cylinder groups and a plurality of variable valve timing mechanisms provided for each of the cylinder groups and capable of adjusting opening / closing timing of at least one of an intake valve and an exhaust valve of the cylinder group. In the engine, when the variable valve timing mechanism of one cylinder group malfunctions, the valve timing of the variable valve timing mechanism of another cylinder group that does not malfunction is determined by the amount of overlap between the intake valve and the exhaust valve. A variable valve timing control device for an internal combustion engine, comprising a drive control means capable of forcibly setting a timing at which the pressure becomes smaller. 2. The variable valve timing control device for an internal combustion engine according to claim 1, wherein: an operating state detecting means for detecting an operating state of the internal combustion engine; and a variable valve timing provided for each of the variable valve timing mechanisms. A plurality of actual timing detection means for detecting actual valve timing of a valve adjusted by a mechanism; and as the drive control means, a variable valve timing mechanism according to an operation state of the internal combustion engine detected by the operation state detection means. Target timing calculating means for calculating a target valve timing of the valve; detecting an operation failure for each of the variable valve timing mechanisms based on a deviation between the target valve timing by the target timing calculating means and each actual valve timing by the actual timing means. Malfunction detecting means for performing the Means for detecting an operation failure of the variable valve timing mechanism, setting the target valve timing of the variable valve timing mechanism in which the operation failure has not been detected in accordance with the valve timing of the variable valve timing mechanism in which the operation failure has occurred. A variable valve timing control device for an internal combustion engine, comprising: overlap amount setting means for forcibly setting a timing at which the overlap amount becomes small. 3. The variable valve timing control device for an internal combustion engine according to claim 2, wherein said overlap amount setting means detects a malfunction when said malfunction detection means detects a malfunction of said variable valve timing mechanism. A variable valve timing control apparatus for an internal combustion engine for forcibly setting a target valve timing of a variable valve timing mechanism in which no overlap is detected to a timing at which the overlap amount is minimized.