JPH10220259A - Valve timing control device for internal combustion engine - Google Patents

Abstract

(57) [Summary] [PROBLEMS] Hydraulic drive type variable valve timing (VVT)
In an internal combustion engine equipped with a mechanism, it is possible to detect a state in which air is mixed into the hydraulic system and the oil pressure and oil amount are abnormally reduced by a simple method, and when such an abnormality is detected, a failure may occur. The VVT mechanism is controlled so as not to be present. SOLUTION: Air is mixed into a hydraulic system, and a VVT mechanism 7 is formed.
When the hydraulic pressure and the oil amount supplied to 0 decrease, the moving speed of the helical splined ring gear in the mechanism, that is, the speed of the relative rotation of the camshaft 13 with respect to the crankshaft 7 increases, so that the relative rotational speed is detected. Thus, the mixing of air is determined. Further, when such air entrapment is detected, by setting the target valve timing displacement amount to half of the maximum value, control for positioning the ring gear at the intermediate position is performed to avoid collision of the ring gear with the stopper. .

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 mechanism (hereinafter referred to as "VVT") capable of continuously changing the timing of opening and closing an intake valve or an exhaust valve.
The present invention also relates to a valve timing control apparatus for controlling a VVT mechanism by setting a target valve timing in an internal combustion engine having a hydraulic drive type.

[0002]

2. Description of the Related Art Conventionally, various variable mechanisms of a valve train have been put to practical use in an automobile engine in order to achieve an optimal valve timing according to an operating state. The main type of such a variable mechanism is a two-stage switching type, that is, an ON / OFF control type.
In recent years, in order to respond to the demand for higher performance of engines, such variable valve timing mechanisms must always set an optimal valve timing instead of the conventional two-stage switching type. A continuously variable type that is capable of being developed is being developed. In an internal combustion engine having a variable valve timing mechanism, in view of contributing intake efficiency to the improvement of the output performance, and contributes to the improvement of the fuel economy due to a reduction in improved and pumping loss of the exhaust gas purification performance (emission) due to the reduction of the NO _x From the viewpoint of internal exhaust gas recirculation (internal EGR), the valve timing is controlled according to the engine operating state.

For example, Japanese Patent Application Laid-Open No. Hei 8-218823 discloses a VVT
An example of a valve timing control device in an internal combustion engine having a mechanism is disclosed. In the VVT mechanism disclosed in the publication, a timing pulley that is driven to rotate by a timing belt that transmits the rotation of a crankshaft and a camshaft that drives a valve are connected by a ring gear having helical splines (twisted vertical grooves) on the inner and outer circumferences. By moving the movable piston integrated with the ring gear in the axial direction by oil pressure, the rotational phase of the two is shifted to continuously change the valve timing.

[0004]

It has been pointed out that in the above-described hydraulically driven VVT mechanism, a malfunction may occur when the hydraulic pressure and oil amount decrease. In other words, when driving a car with the oil pressure and oil amount reduced,
Air starts to enter from the oil pump. In particular, when the vehicle turns, the oil level fluctuates, so that air is likely to be mixed. If the VVT mechanism continues to be driven in the state where the oil pressure and the oil amount are reduced, the above-described ring gear shifts from a predetermined position, and its moving speed increases. When the ring gear is controlled by setting the target value to a position near both ends of the range in which the ring gear can be displaced, the ring gear collides with stoppers provided on both ends of the displacement, generating a tapping sound and abnormal wear. Happens. A system that detects an abnormality in oil pressure and oil amount by a sensor and turns on a warning lamp to notify a user of the abnormality has been adopted in many vehicles.
During a turn, the user is distracted by driving and is less likely to notice it.

In view of the above circumstances, an object of the present invention is to provide an internal combustion engine having a hydraulically driven variable valve timing mechanism in which air is mixed into a hydraulic system and the hydraulic pressure and oil amount are abnormally reduced. And a valve timing control device capable of controlling the hydraulically driven variable valve timing mechanism so that no trouble occurs when such abnormality is detected. .

[0006]

According to a first aspect of the present invention, the rotation is transmitted from a rotating body that rotates in conjunction with a crankshaft to a camshaft that drives a valve. And by rotating the camshaft relative to the rotating body within a predetermined angle range in accordance with the supplied hydraulic pressure, a phase difference between the rotating phase of the rotating body and the rotating phase of the camshaft. A rotation transmission member that makes the rotation variable, a control unit that controls a hydraulic pressure to be supplied to the rotation transmission member according to an engine operating state, and a speed of relative rotation of the camshaft with respect to the rotating body by the rotation transmission member. A valve timing control device for an internal combustion engine, comprising: a detection unit for detecting; and a determination unit for determining whether there is an abnormality in a hydraulic system based on a relative rotational speed detected by the detection unit. It is provided.

According to a second aspect of the present invention, in the above apparatus, the determining means determines that the hydraulic system is abnormal when the relative rotation speed is higher than a predetermined value. And the control means controls the hydraulic pressure to the rotation transmitting member such that when the determination means determines that there is an abnormality, the cam shaft relatively rotates to a substantially intermediate position within the predetermined angle range. Is what you do.

[0008] In the valve timing control apparatus for an internal combustion engine according to the first aspect of the present invention configured as described above, air is mixed into the hydraulic system to supply the hydraulic pressure supplied to the rotation transmitting member. When the amount of liquid decreases, the speed of the relative rotation of the camshaft with respect to the rotating body increases. By detecting this, it becomes possible to determine the incorporation of air. Further, according to the second aspect of the present invention, when such an abnormality occurs, the hydraulic pressure to the rotation transmitting member is controlled such that the camshaft relatively rotates to the substantially middle position within the predetermined angle range, and thus the rotation is controlled. The occurrence of a collision in the transmission member is suppressed.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an overall schematic diagram of an electronically controlled internal combustion engine provided with a valve timing control device according to one embodiment of the present invention. The vehicle is equipped with a four-cycle gasoline engine (hereinafter simply referred to as engine) 1 as an internal combustion engine. The engine 1 includes a cylinder block 2 and a cylinder head 3. A plurality of cylinders 4 extending in the vertical direction are arranged in the cylinder block 2 in parallel in the thickness direction of the drawing, and a piston 5 is accommodated in each cylinder 4 so as to be reciprocable. Each piston 5 is connected to a common crankshaft 7 via a connecting rod 6. The reciprocating motion of each piston 5 is converted into a rotational motion of a crankshaft 7 via a connecting rod 6.

A combustion chamber 8 is provided between the cylinder block 2 and the cylinder head 3 above each piston 5. The cylinder head 3 is provided with an intake port 9 and an exhaust port 10 for communicating both outer surfaces thereof with the respective combustion chambers 8. In order to open and close these ports 9 and 10, an intake valve 11 and an exhaust valve 12 are supported on the cylinder head 3 so as to be able to reciprocate substantially vertically. In the cylinder head 3,
Above each valve 11, 12, an intake side camshaft 1 is provided.
3 and the exhaust-side camshaft 14 are provided rotatably. Camshafts 13 and 14 have cams 15 for driving the intake valve 11 and the exhaust valve 12.
And 16 are attached. Timing pulleys 17 provided at the ends of camshafts 13 and 14, respectively.
And 18 are connected by a timing belt 20 to a timing pulley 19 provided at the end of the crankshaft 7.

That is, when the timing pulley 19 rotates with the rotation of the crankshaft 7, the rotation is transmitted via the timing belt 20 to the timing pulleys 17 and 1.
8 is transmitted. At this time, the rotation of the timing pulley 19 is transmitted to the timing pulleys 17 and 18 with its rotation speed reduced to half. When the intake side camshaft 13 rotates with the rotation of the timing pulley 17,
The intake valve 11 is reciprocated by the action of the cam 15, and the intake port 9 is opened and closed. When the exhaust camshaft 14 rotates with the rotation of the timing pulley 18, the exhaust valve 12 reciprocates by the action of the cam 16, and the exhaust port 10 is opened and closed. Thus, the camshafts 13 and 14 are rotationally driven by the crankshaft 7, and the intake valve 11 and the exhaust valve 12 are opened and closed at a constant crank angle of 720 ° cycle.

The intake port 9 is connected to an intake passage 30 having an air cleaner 31, a throttle valve 32, a surge tank 33, an intake manifold 34 and the like. The air (outside air) outside the engine 1 sequentially passes through the respective portions 31, 32, 33, and 34 of the intake passage 30 toward the combustion chamber 8. The throttle valve 32 is rotatably provided in the intake passage 30 by a shaft 32a. The shaft 32a is connected to an accelerator pedal (not shown) in the driver's seat via a wire or the like, and is rotated integrally with the throttle valve 32 in conjunction with the depression operation of the accelerator pedal by the driver. The amount of air flowing through the intake passage 30 (the amount of intake air) is determined according to the inclination angle of the throttle valve 32 at this time. The surge tank 33 is for smoothing the pulsation (pressure vibration) of the intake air. In addition, the idle adjustment passage 3 that bypasses the throttle valve 32
5 is provided with an idle rotation speed control valve (ISCV) 36 for adjusting the air flow during idling.

Each intake port 9 has an intake manifold 34.
An injector 40 for injecting fuel toward is mounted. The fuel is stored in a fuel tank 41, from which the fuel is pumped by a fuel pump 42, and a fuel pipe 4
3 and is supplied to the injector 40. Then, a mixture of fuel injected from the injector 40 and air flowing in the intake passage 30 is introduced into the combustion chamber 8 via the intake valve 11.

A spark plug 50 is attached to the cylinder head 3 to ignite the mixture. At the time of ignition, the igniter 51 that has received the ignition signal controls the supply and cutoff of the primary current of the ignition coil 52, and the secondary current is supplied to the ignition plug 5 via the ignition distributor 53.
0 is supplied. The ignition distributor 53 distributes the secondary current to the ignition plug 50 of each cylinder in synchronization with the rotation of the crankshaft 7. And the combustion chamber 8
The air-fuel mixture introduced into the fuel cell is exploded and burned by ignition by the spark plug 50. The piston 5 reciprocates by the high-temperature and high-pressure combustion gas generated at this time, the crankshaft 7 is rotated, and the driving force of the engine 1 is obtained.

The burned air-fuel mixture is guided as exhaust gas to an exhaust port 10 via an exhaust valve 12. The exhaust port 10 has an exhaust manifold 61 and a catalytic converter 62.
The exhaust passage 60 provided with the above is connected. HC (hydrocarbon), which is an incomplete combustion component, is supplied to the catalytic converter 62.
And a three-way catalyst that simultaneously promotes the oxidation of CO (carbon monoxide) and the reduction of NO _x (nitrogen oxide) generated by the reaction of nitrogen in the air with unburned oxygen. . The exhaust gas thus purified in the catalytic converter 62 is discharged into the atmosphere.

In particular, in the engine 1, a generally known continuously variable valve timing mechanism 70 is provided between the intake side camshaft 13 and the timing pulley 17 (a rotating body that rotates in conjunction with the crankshaft). Have been. This is because the camshaft 13 and the timing pulley 1
And 7 are relatively rotated. That is, the continuously variable valve timing mechanism 70 uses the camshaft 13 and the timing pulley 17 as external teeth, connects them via ring gears having helical splines on the inner and outer circumferences, and moves the ring gears in the axial direction. The aforementioned relative rotation is realized. The movement of the ring gear is performed by controlling a hydraulic pressure supplied from a hydraulic pressure source, and an oil control valve (OCV) 110 is provided for controlling the hydraulic pressure.

Next, details of the VVT mechanism 70 and the OCV 110 will be described with reference to FIGS. The intake camshaft 13 is rotatably supported by the journal 71 between the cylinder head 3 and the bearing cap 72. A timing pulley 17 is mounted on the outer periphery of the camshaft 13 near the front of the journal 71 (leftward in FIGS. 2 and 4) so as to be relatively rotatable.
A large number of external teeth 73 are formed on the outer periphery of the timing pulley 17, and the timing belt 20 is mounted on the external teeth 73.
As described above, the rotation of the crankshaft 7 is transmitted to the timing pulley 17 via the timing belt 20.

An inner cap 75 is attached to the front end of the camshaft 13 by a hollow bolt 76 and a pin 77 so as to be integrally rotatable. The timing pulley 17
A cover 79 having a lid 78 is attached by a bolt 80 and a pin 81 so as to be integrally rotatable. This cover 79
The front end of the camshaft 13 and the inner cap 7
5 is entirely covered.

Timing pulley 17 and camshaft 1
3 is connected by a ring gear 82 interposed between the cover 79 and the inner cap 75. The ring gear 82 has a substantially annular shape, and a space S surrounded by the timing pulley 17, the cover 79, and the inner cap 75.
It is housed inside so as to be able to reciprocate in the front-rear direction. A number of teeth 82a and 82b are provided on the inner and outer circumferences of the ring gear 82. Correspondingly, a number of teeth 75a, 79b are provided on the outer circumference of the inner cap 75 and the inner circumference of the cover 79. These teeth 82a, 82b, 75a, 7
9 b is a helical tooth whose tooth trace intersects the axis of the camshaft 13. And tooth 7
5a and 82a mesh with each other, and teeth 79b and 82b mesh with each other. Due to these meshes, the rotation of the timing pulley 17 is transmitted to the camshaft 13 via the cover 79, the ring gear 82, and the inner cap 75.
Further, since each tooth 82a, 82b, 75a, 79b is a helical tooth, when the ring gear 82 moves in the front-back direction, a torsional force is applied to the inner cap 75 and the cover 79, and as a result, the camshaft 13 It rotates relative to the timing pulley 17.

In the space S, the front side of the ring gear 82 forms a first hydraulic chamber 83, and the rear side forms a second hydraulic chamber 85. As shown in FIG. 3 and FIG. 5, the engine 1
The existing oil pump 86 is used. The oil pump 86 is drivingly connected to the crankshaft 7,
It operates with the operation of the engine 1 to suck and discharge lubricating oil from the oil pan 87. Foreign matter in the discharged lubricating oil,
The metal powder and the like are removed by the oil filter 88. Then, the oil pressure of the lubricating oil that has passed through the oil filter 88 is supplied to each of the hydraulic chambers 83 and 85.

As shown in FIGS. 2 and 4, the oil pump 86 is connected to a first hydraulic chamber 83 by a first supply path described later.
Is communicated to. That is, a head oil passage 90 extending in the vertical direction is formed in the cylinder head 3 and the bearing cap 72. An oil hole 91 is formed in the bearing cap 72 in parallel with the head oil passage 90. Oil hole 9 in journal 71 of camshaft 13
At a location corresponding to 1, a journal groove 92 is formed over the entire circumference.

The camshaft 13 has a shaft oil passage 93 extending along its axis. The shaft oil passage 93 is divided into front and rear by a ball 95 arranged on the way. An oil hole 96 is formed in the camshaft 13 to allow the journal groove 92 and the shaft oil passage 93 to communicate with each other. The front side of the shaft oil passage 93 is communicated with the first hydraulic chamber 83 through the center hole 76a of the hollow bolt 76. Then, the above-described head oil passage 90, oil hole 9
1. A first supply path is constituted by the journal groove 92, the oil hole 96, the shaft oil path 93, and the center hole 76a.

The oil pump 86 is connected to a second hydraulic chamber 85 through a second supply path described later. That is, an oil hole 98 is formed in the bearing cap 72 in parallel with the oil hole 91. A journal groove 99 is formed in the journal 71 of the camshaft 13 at a position corresponding to the oil hole 98 over the entire circumference. The camshaft 13 has a shaft oil passage 1 parallel to the shaft oil passage 93.
00 is formed. The rear end of the shaft oil passage 100 is connected to the journal groove 99, and the front end is connected to the camshaft 13.
It is connected to a second hydraulic chamber 85 via an oil hole 101 provided between the second hydraulic chamber 85 and the inner cap 75. Then, the above-described head oil passage 90, oil hole 98, journal groove 99,
The shaft oil passage 100 and the oil hole 101 constitute a second supply passage.

In the middle of the first supply path and the second supply path, an oil control valve (a solenoid control valve) composed of an electromagnetic linear solenoid valve is used to adjust the magnitude of the hydraulic pressure supplied to each of the hydraulic chambers 83, 85. An OCV) 110 is provided.

As shown in FIGS. 2 and 3, the OCV 110
The first port 113, the second port 114, the third port 11
5, a fourth port 116 and a fifth port 117 are provided. The first port 113 is connected to the oil hole 91, and the second port 114 is connected to the oil hole 98. The third and fourth ports 115 and 116 are connected to an oil pan 87 via an oil hole 118 formed in the bearing cap 72. The fifth port 117
It is connected to an oil pump 86 via a head oil passage 90, an oil filter 88 and the like.

Inside the casing 111, a cylindrical 4
A spool 119 having two valve elements 119a is accommodated so as to be able to reciprocate. The spool 119 is moved before and after the spool 119 (FIG. 3).
Are moved in the axial direction by the operation of the springs 120 and the electromagnetic solenoids 121 provided on both sides.

For example, as shown in FIG.
Is moved forward (to the left in the figure), the fifth port 11
7 is connected to the first port 113, and the second port 114 is connected to the fourth port 116. By these communication, the hydraulic pressure supplied to the head oil passage 90 is
Oil hole 91, journal groove 92, oil hole 9 from OCV110
6. The oil is supplied to the first hydraulic chamber 83 through the shaft oil passage 93 and the center hole 76a. When this oil pressure is applied to the ring gear 82 from the front side, the ring gear 82 rotates while moving backward against the lubricating oil in the second hydraulic chamber 85. By this movement accompanied by the rotation, a torsional force is applied to the inner cap 75 and the cover 79.

As a result, the angle of the relative rotation of the camshaft 13 with respect to the timing pulley 17 is changed, and the valve timing of the intake valve 11 is advanced. That is,
The valve opening start timing of the intake valve 11 is advanced. The rearward movement of the ring gear 82 is caused by the timing pulley 17
It is regulated when it comes into contact with. When the ring gear 82 comes into contact with the timing pulley 17 and stops, the opening timing of the intake valve 11 is the earliest.

On the other hand, as shown in FIG. 3, when the spool 119 of the OCV 110 is moved rearward (to the right in the figure), the fifth port 117 is communicated with the second port 114, and the first port 117 is connected to the first port 114. Port 113 communicates with third port 115. Then, the hydraulic pressure supplied to the head oil passage 90 is supplied from the OCV 110 to the second hydraulic chamber 85 through the oil hole 98, the journal groove 99, the shaft oil passage 100, and the oil hole 101. When this hydraulic pressure is applied to the ring gear 82 from behind, the ring gear 82 rotates while moving forward against the lubricating oil in the first hydraulic chamber 83. By this movement accompanied by the rotation, a torsional force is applied to the inner cap 75 and the cover 79.

As a result, the angle of relative rotation of the camshaft 13 with respect to the timing pulley 17 is changed, and the valve timing of the intake valve 11 is retarded. That is,
The valve opening start timing of the intake valve 11 is delayed. The forward movement of the ring gear 82 is restricted by its contact with the cover 79. When the ring gear 82 comes into contact with the cover 79 and stops, the valve opening start timing of the intake valve 11 becomes the latest, and the valve timing becomes the most retarded state.

The VVT mechanism 70 is configured as described above. By driving the VVT mechanism 70, the valve timing of the intake valve 11 can be arbitrarily changed within a predetermined range.

As shown in FIG. 1, the following various sensors are attached to the engine 1. A water temperature sensor 144 for detecting the temperature of the cooling water of the engine 1 (cooling water temperature THW) is attached to the cylinder block 2. A thermal air flow meter 140 for detecting an intake air amount (mass flow rate GA) is attached to the intake passage 30. An intake air temperature sensor 143 for detecting the temperature of the intake air (intake air temperature THA) is attached near the air cleaner 31 in the intake passage 30. Intake passage 30
In the vicinity of the throttle valve 32, the shaft 3
A throttle opening sensor 142 for detecting the rotation angle 2a (throttle opening TA) is provided. When the throttle valve 32 is in the fully closed state, the idle switch 152 is turned on, and the throttle fully closed signal output from the idle switch 152 becomes active. Surge tank 33
Is provided with an intake pressure sensor 141 for detecting the internal pressure (intake pressure PM). Exhaust passage 60
An O ₂ sensor 145 for detecting the concentration of residual oxygen in the exhaust gas is mounted in the middle of the process.

The distributor 53 has a built-in rotor that rotates in synchronization with the rotation of the crankshaft 7, and converts the crank angle (CA) based on the rotation of the rotor to detect the reference position of the crankshaft 7. A crank reference position sensor 150 for generating a reference position detection pulse every 720 ° CA is provided. In addition, the crank reference position sensor 150 detects the rotation speed of the crankshaft 7 (engine rotation speed NE) based on the rotation of the rotor. A rotation speed detection pulse is generated for each CA and the rotation speed sensor 15
1 is provided. The vehicle is provided with a vehicle speed sensor 153 that generates an output pulse representing the actual vehicle speed.

Further, the engine 1 is provided with a crank angle sensor 154 comprising a rotor on the crankshaft 7 and an electromagnetic pickup. The rotor is made of a magnetic material, and has a plurality of teeth formed at equal angles on the outer periphery thereof. The electromagnetic pickup generates a pulse-like crank angle signal each time the rotor rotates and the teeth pass in front of the electromagnetic pickup with the rotation of the crankshaft 7. Then, after the reference position signal is generated by the crank reference position sensor 150, the rotation angle (crank angle) of the crankshaft 7 can be detected by measuring the number of pulses of the crank angle signal from the crank angle sensor 154. .

Similarly, the engine 1 includes a cam angle sensor 1
55 are provided. The sensor 155 includes a rotor on the intake camshaft 13 and an electromagnetic pickup. The rotor is made of a magnetic material, and has a plurality of teeth formed at equal angles on the outer periphery thereof. The electromagnetic pickup generates a pulse-like cam angle signal each time the rotor rotates as the camshaft 13 rotates and the teeth pass in front of the electromagnetic pickup. By calculating the phase difference between the rotation phase of the camshaft 13 and the rotation phase of the crankshaft 7 based on the cam angle signal and the crank angle signal, the actual valve timing of the intake valve 11 can be detected.

An engine electronic control unit (engine ECU) 170 shown in FIG. 1 is a microcomputer system that executes valve timing control according to the present invention in addition to fuel injection control, ignition timing control, idle speed control, and the like. The hardware configuration is shown in the block diagram of FIG. According to a program and various maps stored in a read-only memory (ROM) 173, the central processing unit (CPU) 171 converts signals from various sensors and switches into an A / D conversion circuit (ADC) 175 or an input interface circuit 176. , And executes arithmetic processing based on the input signal, and outputs various actuator control signals via the drive control circuits 177a to 177d based on the arithmetic result. Random access memory (R
AM) 174 is used as a temporary data storage location during the arithmetic and control processing. Further, the backup RAM 179 is supplied with power by being directly connected to a battery (not shown), and stores data (for example, various learning values) to be held even when the ignition switch is off. Used for Each component in these ECUs is an address bus,
They are connected by a system bus 172 composed of a data bus and a control bus.

The fuel injection control is basically performed by the engine 1
A drive control circuit 177a calculates a fuel injection amount for achieving a predetermined target air-fuel ratio, that is, an injection time by the injector 40, based on the intake air mass per revolution, and injects fuel when a predetermined crank angle is reached. Is used to control the injector 40. The engine 1
The mass of intake air per revolution is calculated using the thermal air flow meter 1
It is calculated from the intake air mass flow rate measured by 40 and the engine rotation speed obtained from the rotation speed sensor 151. In calculating the fuel injection amount, a basic correction based on signals from sensors such as a throttle opening sensor 142, an intake air temperature sensor 143, and a water temperature sensor 144,
An air-fuel ratio feedback correction based on a signal from the O ₂ sensor 145, an air-fuel ratio learning correction for making the median of the feedback correction value a stoichiometric air-fuel ratio, and the like are added.

The ignition timing is controlled by the rotation speed sensor 1
Based on the engine speed obtained from 51 and signals from other sensors, the state of the engine is comprehensively determined,
The optimum ignition timing is determined, and an ignition signal is sent to the igniter 51 via the drive control circuit 177b.

In the idle speed control, the idle state is detected by a throttle fully closed signal from an idle switch 152 and a vehicle speed signal from a vehicle speed sensor 153, and a target determined by an engine coolant temperature from a water temperature sensor 144 and the like. The engine speed is compared with the actual engine speed, a control amount is determined so as to reach the target engine speed according to the difference, and the air amount is adjusted by controlling the ISCV 36 via the drive control circuit 177c. , To maintain an optimum idle rotation speed.

Hereinafter, the valve timing control according to the present invention will be described in detail. The valve timing control is for controlling the continuously variable valve timing mechanism 70 by setting a target valve timing (valve opening / closing timing) of the intake valve 11 in accordance with an operation state. The crank angle sensor 154 and the cam angle described above are used so that the rotation phase maintains a desired phase difference with respect to the rotation phase of the crankshaft 7, that is, the camshaft 13 is relatively rotated by a specific angle with respect to the timing pulley 17. The oil control valve 110 is feedback-controlled based on a signal from the sensor 155.

FIG. 7 shows the intake valve 11 and the exhaust valve 1.
FIG. 4 is a valve timing diagram showing the opening / closing timing of No. 2 by a crank angle. As shown in FIG.
Is opened at a fixed valve opening timing EVO (50 ° before the bottom dead center in the present embodiment), and at a fixed valve closing timing EVC (3 ° after the top dead center in the present embodiment). Is closed. On the other hand, the intake valve 11 has a fixed valve opening period, but has a valve opening timing IVO.
And the valve closing timing IVC is variable, and the opening / closing timing on the most retarded side (IVOr and IVCr in the same figure) is used as a reference position.
Both timings can be set at timings displaced by an arbitrary amount in the advance direction. However, the maximum value of the valve timing displacement amount VTD is 60 ° in the present embodiment. Then, the valve timing displacement amount VTD from the reference position
Is the control target amount. Here, in the present embodiment, as the reference position, the reference valve opening timing IOr is 3 ° after the exhaust top dead center, and the reference valve closing timing IVCr is 65 ° after the intake bottom dead center. Therefore, in this case, when the valve timing displacement amount VTD is, for example, 30 ° CA (crank angle), the IVO becomes 27 ° before the exhaust top dead center, and the IVC
Is 35 ° after the intake bottom dead center. In the present embodiment,
Reference valve opening timing IVOr of intake valve 11 and exhaust valve 2
Since the valve closing timing EVC of No. 6 is the same as 3 ° after the exhaust top dead center, the valve timing displacement amount VTD coincides with the valve overlap amount. However, FIG.
So, in consideration of generality and to make it easier to understand,
IOr and EVO are drawn so as not to match.

By the way, as described above, in the hydraulically driven VVT mechanism 70 as described above, there is a possibility that a malfunction occurs when the hydraulic pressure and the oil amount decrease. FIG. 8 is a time chart illustrating a state in which the actual valve timing displacement (advance angle) VTD deviates from the target valve timing displacement VTDt when the vehicle is turned with the oil amount reduced. That is, when the vehicle is operated in a state where the hydraulic pressure and the oil amount are reduced, air starts to be mixed in from the oil pump 86. In particular, when the vehicle turns, the oil level fluctuates, so that air is likely to be mixed. V when the oil pressure and oil amount are low
When the VT mechanism 70 continues to be driven, the ring gear 82 deviates from the desired control position, and its moving speed increases. When the target value is set at the position closest to the most retarded position or the most advanced position and the ring gear 82 is controlled, the ring gear 82 collides with the cover 79 or the timing pulley 17, generating a tapping sound and a collision. The parts are worn.

As described above, when air is mixed into the hydraulic system, V
When the hydraulic pressure and the amount of oil supplied to the VT mechanism 70 decrease, the moving speed of the ring gear 82, that is, the speed of the relative rotation of the camshaft 13 with respect to the crankshaft 7 increases. The detection is intended to determine the mixing of air. Further, this embodiment, when such air contamination is detected, the target valve timing displacement VTDt the maximum valve timing displacement VTD _max (= 60 ° C
By setting half of A), that is, 30 ° CA, the ring gear 82 is positioned at the intermediate position, and the ring gear 82 is prevented from colliding with the cover 79 and the timing pulley 17.

FIG. 9 is a flowchart showing a processing procedure of a valve timing control routine that embodies the above control principle. This routine is configured to be executed at a predetermined cycle. First, the current engine rotational speed NE is detected based on the output of the rotational speed sensor 151, and the current intake air mass flow rate GA is detected based on the output of the thermal air flow meter 140 (step 2).
02). Next, an engine load (a mass of intake air per one revolution of the engine) GN is calculated by a calculation of GN ← GA / NE (step 204).

Next, it is determined whether or not a hydraulic pressure abnormality detection flag F operated in a later-described routine is set to 1 (step 206). When no oil pressure abnormality is detected, that is, when F = 0, the target valve timing displacement amount VTDt according to the current engine load GN and the engine speed NE is calculated by interpolation calculation based on a map as shown in FIG. Calculate (Step 20
8). The map of the target valve timing displacement VTDt is stored in the ROM 173 in advance. On the other hand, when an oil pressure abnormality is detected, that is, when F = 1, the target valve timing displacement amount VTDt is set to the maximum value VT.
It is set to half of _Dmax , that is, 30 ° CA (step 210).

In the following steps after the target valve timing displacement amount VTDt is determined, feedback control of the OCV 110 is performed. First, the actual valve timing displacement amount VTD obtained by the previous running of this routine is
It is stored as TDO (step 212). VT
DO is used in a routine described later. Next, the current actual valve timing displacement VTD is detected based on the phase difference between the crank angle signal from the crank angle sensor 154 and the cam angle signal from the cam angle sensor 155 (step 214). Next, the actual valve timing displacement amount V
A required valve timing advance amount ΔVTD representing how much the TD is retarded from the target valve timing displacement amount VTDt, that is, how much the TD needs to be advanced, is calculated by an operation of ΔVTD ← VTDt−VTD (step 216). Therefore,
When ΔVTD <0, it indicates that it is necessary to retard the actual valve timing displacement amount VTD.

Next, by referring to a map as shown in FIG. 11, the required valve timing advance amount ΔVTD
, A duty ratio increase request amount ΔDR representing how much the duty ratio DR for controlling the OCV 110 needs to be increased is obtained (step 218). As shown in the figure, when ΔVTD> 0, ΔDR>
0, ΔVTD = 0, ΔDR = 0, ΔVTD <0
At the time, ΔDR <0. Finally, the duty ratio D
R is updated by an operation of DR ← DR + ΔDR to control the OCV 110 (step 220). This routine is started at a predetermined cycle, and the above-described steps 214, 216, 218, and 220 are repeatedly executed, thereby realizing feedback control.

FIG. 12 is a flowchart showing a processing procedure of a hydraulic pressure / oil amount abnormality detection routine for operating the oil pressure abnormality detection flag F. This routine is configured to be executed at the same cycle as the cycle of the above-described valve timing control routine. First, it is determined whether the deviation of the current actual valve timing displacement VTD from the target valve timing displacement VTDt is less than 5 ° CA (step 30).
2) If it is less than 5 ° CA, this routine ends.
On the other hand, at 5 ° CA or more, the change speed of the phase difference between the rotation phase of the crankshaft 7 and the rotation phase of the camshaft 13, that is, the speed S [° CA / sec] of the relative rotation of the camshaft 13 with respect to the crankshaft 7 Is obtained by an operation of S ← (VTD−VTDO) / T (step 304). Note that T
Is an execution cycle of the valve timing control routine.

Next, it is determined whether or not the absolute value | S | of the relative rotational speed is greater than a predetermined reference value α [° CA / sec] (step 306). When | S | ≦ α, the present routine is terminated. However, when | S |> α, it is considered that there is an abnormality in the hydraulic pressure and oil amount due to the mixing of air, the hydraulic pressure abnormality detection flag F is set to 1 (step 308), and this routine ends. Note that this flag F is, as shown in FIG.
Is reset together with the initialization of the RAM (step 402) (step 40).
If only abnormality is detected during the operation of the engine, the state remains set until the power-off time. As a result, it is possible to prevent hitting noise and wear.

Although the embodiments of the present invention have been described above, the present invention is of course not limited to these embodiments. For example, the present embodiment employs a so-called ring gear type VV.
Although a T mechanism is used, a so-called vane type VV
The present invention is applicable to the T mechanism as long as it is of a hydraulic drive type. Further, the present embodiment has been described with respect to an engine employing a belt drive system as a camshaft drive system, but the present invention is also applicable to a chain drive system or a gear drive system.

[0052]

As described above, according to the present invention,
A simple method of monitoring the relative rotation speed of the camshaft in a state where air is mixed into the hydraulic system and the hydraulic pressure and fluid volume are abnormally reduced in an internal combustion engine equipped with a hydraulically driven variable valve timing mechanism Can be detected. Also,
When such an abnormality is detected, by setting the relative rotation angle of the camshaft to a substantially intermediate value, it becomes possible to control the hydraulically driven variable valve timing mechanism so that no trouble occurs. In addition, the present invention
There is also an effect that there is no need to provide a hot water sensor.

[Brief description of the drawings]

FIG. 1 is an overall schematic diagram of an electronically controlled internal combustion engine including a valve timing control device according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of the VVT mechanism when the VVT mechanism is driven so as to achieve the most retarded state of the intake valve timing.

FIG. 3 is a partial cross-sectional view of an OCV when an oil control valve (OCV) is controlled so as to achieve a most retarded state of intake valve timing.

FIG. 4 is a partial cross-sectional view of the VVT mechanism when the VVT mechanism is driven so as to achieve the most advanced state of the intake valve timing.

FIG. 5 is a partial cross-sectional view of the OCV when the oil control valve (OCV) is controlled so as to achieve the most advanced state of the intake valve timing.

FIG. 6 is a block diagram showing a hardware configuration of an engine ECU according to one embodiment of the present invention.

FIG. 7 is a valve timing chart showing the opening and closing timings of an intake valve and an exhaust valve by a crank angle.

FIG. 8 is a time chart illustrating a state in which the actual valve timing displacement amount (advance angle from the most retarded position) VTD deviates from the target valve timing displacement amount VTDt when the vehicle is turned with the oil amount reduced. It is.

FIG. 9 is a flowchart illustrating a processing procedure of a valve timing control routine.

FIG. 10 shows an engine speed NE and an engine load GN.
FIG. 7 is a diagram showing a map for obtaining a target valve timing displacement amount VTDt according to FIG.

FIG. 11 is a view showing a map for obtaining an OCV control duty ratio increase request amount ΔDR according to a valve timing advance request amount ΔVTD.

FIG. 12 is a flowchart illustrating a processing procedure of a hydraulic pressure / oil amount abnormality detection routine.

FIG. 13 is a flowchart illustrating a processing procedure of an initialization routine.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... 4 cycle gasoline engine 2 ... Cylinder block 3 ... Cylinder head 4 ... Cylinder 5 ... Piston 6 ... Connecting rod 7 ... Crankshaft 8 ... Combustion chamber 9 ... Intake port 10 ... Exhaust port 11 ... Intake valve 12 ... Exhaust valve 13 ... Intake side camshaft 14 ... Exhaust side camshaft 15 ... Intake side cam 16 ... Exhaust side cam 17,18,19 ... Timing pulley 20 ... Timing belt 30 ... Intake passage 31 ... Air cleaner 32 ... Throttle valve 32a ... Throttle valve shaft 33 ... Surge tank 34 ... Intake manifold 35 ... Idle adjust passage 36 ... Idle speed control valve (ISCV) 40 ... Injector 41 ... Fuel tank 42 ... Fuel pump 43 ... Fuel pipe 50 ... Spark plug 51 ... Igniter 52 ... Ignition coil DESCRIPTION OF SYMBOLS 3 ... Ignition distributor 60 ... Exhaust passage 61 ... Exhaust manifold 62 ... Catalyst converter 70 ... Continuously variable valve timing mechanism 110 ... Oil control valve (OCV) 140 ... Air flow meter 141 ... Intake pressure sensor 142 ... Throttle opening sensor 143 ... Intake air temperature sensor 144 ... temperature sensor 145 ... O ₂ sensor 150 ... crank reference position sensor 151 ... rotational speed sensor 152 ... idle switch 153 ... vehicle speed sensor 154 ... crank angle sensor 155 ... cam angle sensor

Claims (2)

[Claims] 1. A camshaft that transmits rotation from a rotating body that rotates in conjunction with a crankshaft to a camshaft that drives a valve, and moves the camshaft relative to the rotating body in a predetermined angle range according to a supplied hydraulic pressure. A rotation transmission member for making the phase difference between the rotation phase of the rotating body and the rotation phase of the cam shaft variable by rotating relatively within the rotation transmission member; Control means for controlling the rotation of the camshaft relative to the rotating body by the rotation transmitting member; detecting means for detecting the relative rotation speed of the camshaft relative to the rotating body; A valve timing control device for an internal combustion engine, comprising: a determination unit configured to determine whether there is an abnormality. 2. The determining means determines that there is an abnormality in the hydraulic system when the relative rotation speed is higher than a predetermined value, and the control means determines that there is an abnormality by the determining means. 2. The valve of the internal combustion engine according to claim 1, wherein, when determined, the hydraulic pressure to the rotation transmitting member is controlled such that the camshaft relatively rotates to a substantially intermediate position within the predetermined angle range. Timing control device.