JPH1136905A - Valve timing control device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a valve timing control device which can obtain an appropriate holding control value upon starting or during cold operation, and which can prevent occurrence of detrimental affection upon an engine, such as inferior acceleration. SOLUTION: In order to realize a change of opening and closing timing of an intake valve 21 for an engine 20, a variable valve timing mechanism (VVT) 50 which is hydraulically driven, is provided. The VVT 50 is controlled through duty control of an oil control valve (OCV) 80 by an electronic control device (ECU) 70. During operation of the engine 10, the ECU 70 suitably updates a holding duty value. During starting or cold operation of the engine 10, the ECU 70 uses a learned holding duty value as the holding duty value. Upon leaning, the ECU 70 allows updating of the holding duty value under leaning only when the temperature of cooling water is higher than a predetermined value. Thus, a holding duty value adapted to be used upon next starting or during next cold operation can become substantially appropriate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve timing control device for an engine having a variable valve timing mechanism for changing at least one of an intake valve and an exhaust valve.

[0002]

2. Description of the Related Art Conventionally, as this kind of technology, Japanese Patent Laid-Open Publication No.
One disclosed in Japanese Patent No. 74530 is known. In this technique, the control oil pressure supplied to the variable valve timing mechanism (VVT) is controlled by controlling the control valve (OCV) based on the control duty value, thereby controlling the VVT and, consequently, the valve timing. . When calculating the control duty value, first, a target value of VVT is calculated based on the operating state of the engine, and a deviation between the target value and the actual valve timing is calculated. Then, a control duty value is calculated based on the deviation and the holding duty value.
The holding duty value is a duty value when the advance angle speed of the VVT becomes "0", in other words, a duty value for maintaining the current advance angle value.

[0003] The holding duty value can fluctuate depending on the manufacturing tolerance of the OCV, the change with time, the temperature of the hydraulic oil, the engine speed, and the like. For this reason, in the above-described technology, the holding duty value is updated according to the current operating state, except immediately after the start or when the oil temperature is equal to or lower than a predetermined temperature (for example, α2 in FIG. 7). Further, in the above-described related art, the holding duty value is learned and updated so as to be used at the next engine start or the like. That is, in the above-described conventional technology, the control duty value is learned at the same time as the holding duty value is updated (stored in the RAM), and at the next engine start, the control duty value is calculated using the previously held holding duty value. It is calculated.

[0004]

However, the above prior art has the following problems. That is, the present inventors have found that the actual holding duty value DA with respect to the oil temperature (or water temperature), as shown in FIG.
It has been found that the relationship is high between 1) and the high temperature side (for example, α4), and low in the middle region (for example, α3). In such a situation, when learning control is performed as in the above-described related art, the following problems may occur.

[0005] That is, it is assumed that during the previous operation, the holding duty value DA was learned at the oil temperature α3 in the intermediate region, and then the engine was stopped. Then, when the engine is started at the low temperature side oil temperature α1 at the next operation, although the appropriate holding duty value DA is β3 corresponding to the oil temperature α1, the above-described prior art learns the previous time. Β1 corresponding to the oil temperature α3 will be adopted as the holding duty value DA. Therefore, the deviation ΔDA between β3 and β1
There is a possibility that a VVT control error (error to the retard side) corresponding to 1 may occur. As a result, there is a possibility that insufficient torque may result due to insufficient amount of advance of the VVT and, consequently, poor acceleration.

The present invention has been made in view of the above circumstances, and has as its object to calculate a control value based on a holding control value, and to control a variable valve timing mechanism based on the control value. Provided is a valve timing control device, which can obtain an appropriate holding control value at the time of starting or in a cold state, and can thereby prevent adverse effects on the engine such as poor acceleration, etc. It is in.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, the intake passage and the intake passage which are driven at predetermined timings in synchronization with the crankshaft of the engine and communicate with the combustion chamber are provided. An intake valve and an exhaust valve that respectively open and close an exhaust passage; a variable valve timing mechanism that changes a valve timing of at least one of the intake valve and the exhaust valve; an actuator that drives the variable valve timing mechanism; Operating state detecting means for detecting an operating state of the valve, target valve timing calculating means for calculating a target value of valve timing changed by the variable valve timing mechanism based on a detection result of the operating state detecting means, and the variable valve Actual valve timing changed by timing mechanism Actual valve timing detection means for detecting the timing, deviation calculation means for calculating a deviation between the target value calculated by the target valve timing calculation means and the actual valve timing detected by the actual valve timing detection means, Control value calculating means for calculating a control value based on at least the deviation calculated by the deviation calculating means and a holding control value for maintaining the advance amount of the variable valve timing mechanism at a constant amount; and Control means for controlling the variable valve timing mechanism by controlling the actuator based on the control value calculated by the value calculation means, and holding control value learning means for learning and updating the holding control value during operation of the engine. When the engine is started or cold, the holding control learning value learned by the learning means is used. A variable valve timing control device for an engine having a holding control value, wherein learning updating of the holding control value learning means is provided only when the temperature of the engine is equal to or higher than a predetermined temperature. This is the gist.

According to a second aspect of the present invention, in the variable valve timing control apparatus for an engine according to the first aspect, the predetermined temperature or more is satisfied when the engine is completely warmed up. The gist is that it is something.

According to a third aspect of the present invention, in the variable valve timing control apparatus for an engine according to the first or second aspect, the actuator adjusts a control oil pressure supplied to the variable valve timing mechanism. The gist is that the oil control valve is duty controlled.

According to the first aspect of the present invention, the intake valve and the exhaust valve are driven at predetermined timings in synchronization with the crankshaft of the engine, and the intake valve or the exhaust passage communicates with the combustion chamber. Open and close respectively. The variable valve timing mechanism is driven by an actuator to change the valve timing of at least one of the intake valve and the exhaust valve.

The operating state of the engine is detected by the operating state detecting means. Based on the detection result, the target valve timing calculating means calculates a target value of the valve timing changed by the variable valve timing mechanism. The actual valve timing detecting means detects the actual valve timing changed by the variable valve timing mechanism. Further, a deviation between the target value calculated by the target valve timing calculating means and the actual valve timing detected by the actual valve timing detecting means is calculated by the deviation calculating means. The control value calculation means calculates a control value based on at least the deviation calculated by the deviation calculation means and a holding control value for maintaining the advance amount of the variable valve timing mechanism at a constant amount. . Based on the control value, the control means controls the actuator to control the variable valve timing mechanism.

During the operation of the engine, the holding control value is learned and updated by the holding control value learning means. Therefore, the holding control value may fluctuate due to a manufacturing tolerance of the actuator or the like, a change over time, or the like. By performing the learning update, the holding control value is optimized.

Further, when the engine is started or when the engine is cold, the holding control learning value learned by the learning means is used as the holding control value. By the way, as pointed out in the problem to be solved by the invention, the actual holding duty value with respect to the engine temperature (for example, oil temperature or water temperature) is high on the low temperature side and high temperature side and low in the middle range. . On the other hand, in the present invention, the learning update of the holding control value learning means is permitted by the learning update permission means only when the engine temperature is equal to or higher than the predetermined temperature. For this reason, the holding control learning value at which the learning update is permitted only at the predetermined temperature or higher, that is, only at the high temperature side, does not significantly differ from the actual holding control value at the low temperature side. Alternatively, the holding control value used in the cold state can be substantially appropriate.

According to the second aspect of the present invention, in addition to the operation of the first aspect, the predetermined temperature or more is satisfied when the engine is completely warmed up. For this reason, the above operation is more reliably achieved.

Further, according to the third aspect of the present invention,
In addition to the functions of the first and second aspects of the invention, the actuator is an oil control valve that is duty-controlled to adjust a control oil pressure supplied to the variable valve timing mechanism. That is, the holding duty value of the oil control valve used at the time of the next start or at the time of cold can be substantially appropriate.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the engine valve timing control device of the present invention is embodied in a gasoline engine will be described below with reference to the drawings.

First, the configuration of the valve timing control device VC of the engine 10 will be described with reference to FIGS. FIG. 1 is a schematic configuration diagram showing a gasoline engine system including an engine valve timing control device VC.

The engine 10 includes a cylinder block 11 in which a plurality of cylinders are formed, and a cylinder block 1.
1 includes a cylinder head 12 connected to an upper portion, and a piston 13 that reciprocates up and down in each cylinder of the cylinder block 11. A crankshaft 14 is connected to the lower end of the piston 13.
The crankshaft 14 is rotated by the vertical movement of the crankshaft 3.

A crank angle sensor 40 is provided near the crankshaft 14. The crank angle sensor 40 includes a magnetic rotor (not shown) connected to the crankshaft 14 and an electromagnetic pickup (not shown). (Not shown). Here, equiangular teeth having missing teeth are formed on the outer periphery of the rotor, and every time the equiangular teeth of the rotor pass in front of the electromagnetic pickup, a pulse-like crank angle signal is detected. Then, the rotation angle (crank angle) of the crankshaft 14 is detected by measuring the number of generations of the crank angle signal from the crank angle sensor 40 after the generation of the reference position signal by the cylinder determination sensor 42 described later.

The space defined by the inner wall of each cylinder block 11 and the cylinder head 12 and the top of the piston 13 defines a combustion chamber 1 for burning an air-fuel mixture.
Functions as 5. At the top of the cylinder head 12, an ignition plug 16 for igniting the air-fuel mixture is provided so as to project into the combustion chamber 15. Each spark plug 1
6 is connected to the distributor 18 via a plug cord or the like (not shown). The high voltage output from the igniter 19 is supplied to the distributor 18
Thus, the fuel gas is distributed to each spark plug 16 in synchronization with the crank angle.

Further, the distributor 18 is connected to the exhaust-side camshaft 33 and is connected to the crankshaft 1.
An engine speed sensor 41 for detecting the speed of the engine 4 is provided. The engine speed sensor 41 includes a magnetic rotor (not shown) that rotates in synchronization with the crankshaft 14 and an electromagnetic pickup (not shown).
The electromagnetic pickup detects the number of rotations of the rotor, so that the number of rotations of the crankshaft 14 (engine speed N
E) will be detected. Further, the distributor 18 is provided with a cylinder discriminating sensor 42 for detecting a reference position of the crank at a predetermined ratio from the rotation of the rotor.

The cylinder block 11 is provided with a water temperature sensor 43 for detecting a temperature (cooling water temperature) THW of the cooling water flowing through the cooling water passage. Cylinder head 1
2 has an intake port 22 and an exhaust port 32, the intake port 22 is connected to the intake passage 20, and the exhaust port 32 is connected to the exhaust passage 30. In addition, the intake port 22 of the cylinder head 12 includes:
An intake valve 21 is provided, and an exhaust port 31 is provided with an exhaust valve 31.

An intake camshaft 2 for opening and closing the intake valve 21 is provided above the intake valve 21.
The exhaust side camshaft 33 for opening and closing the exhaust valve 31 is disposed above the exhaust valve 31. At one end of each of the camshafts 23 and 33, an intake-side timing pulley 27 and an exhaust-side timing pulley 34 are mounted.
7 and 34 are connected to the crankshaft 14 via a timing belt 35.

Therefore, when the engine 10 is operated, the camshafts 23, 3 are transmitted from the crankshaft 14 via the timing belt 35 and the timing pulleys 27, 34.
3 is transmitted to the respective camshafts 23, 33.
, The intake valve 21 and the exhaust valve 31 are opened and closed. These valves 21 and 31 are
At a predetermined opening / closing timing, in synchronization with the rotation of the crankshaft 14 and the vertical movement of the piston 13, that is, in synchronization with a series of four strokes of the engine 10 including an intake stroke, a compression stroke, an explosion / expansion stroke, and an exhaust stroke. Driven.

Further, a cam angle sensor 44 for detecting the valve timing of the intake valve 21 is provided near the intake side camshaft 23.
Reference numeral 4 denotes a magnetic rotor (not shown) connected to the intake-side camshaft 23 and an electromagnetic pickup. A plurality of teeth are formed at equal angles on the outer circumference of the magnetic rotor. For example, before the compression top dead center (TDC) of a predetermined cylinder, between 90 ° and 30 ° BTDC, the intake side cam is formed. A pulse-like cam angle signal accompanying the rotation of the shaft 23 is detected.

An air cleaner 24 is connected to the air intake side of the intake passage 20, and a throttle valve 26 which is opened and closed in conjunction with an accelerator pedal (not shown) is provided in the middle of the intake passage 20. ing. The intake air amount is adjusted by opening and closing the accelerator pedal.

In the vicinity of the throttle valve 26, there are provided a throttle sensor 45 for detecting the throttle opening TA and a fully closed switch 46 for detecting that the throttle valve 26 is fully closed.

Further, on the downstream side of the throttle valve 26,
A surge tank 25 for suppressing intake pulsation is formed. The surge tank 25 is provided with an intake pressure sensor 47 that detects an intake pressure (PiM) in the surge tank 25. An injector 17 for supplying fuel to the combustion chamber 15 is provided near the intake port 22 of each cylinder. Each injector 17 is an electromagnetic valve that is opened by energization, and each injector 17 is supplied with fuel pumped from a fuel pump (not shown).

Therefore, when the engine 10 is operating, the air filtered by the air cleaner 24 is taken into the intake passage 20, and fuel is injected from each injector 17 toward the intake port 22 at the same time as taking in the air. You. As a result, an air-fuel mixture is generated at the intake port 22, and the air-fuel mixture is sucked into the combustion chamber 15 with the opening of the intake valve 21 that is opened during the intake stroke.

A catalytic converter 36 containing a three-way catalyst for purifying exhaust gas is disposed in the exhaust passage 30. In the middle of the exhaust passage 30, an oxygen sensor 48 for detecting the oxygen concentration in the exhaust gas is provided.

Further, the engine 10 includes the engine 1
A starter 28 for starting 0 is provided.
The starter 28 is provided with a starter switch 49 for detecting the operation state. Starter switch 4
Reference numeral 9 denotes a starter signal ST when an ignition switch (not shown) is operated by the driver from an OFF position to a start position when the engine 10 is started, and the starter is operating (in a cranking state).
A is output as “ON”. Further, when the start of the engine 10 is completed (it becomes a complete explosion state) and the ignition switch is returned from the start position to the ON position, the starter switch 49 sets the starter signal STA to “OFF”.
Output as

In the present embodiment, the above-described crank angle sensor 40, engine speed sensor 41, cylinder discrimination sensor 42, water temperature sensor 43, cam angle sensor 44, throttle sensor 45, fully closed switch 46, intake pressure sensor 47,
The operating state detecting means is constituted by the oxygen sensor 48, the starter switch 49 and the like. In particular, the actual valve timing detection means is constituted by the cam angle sensor 44, the crank angle sensor 40, and the like.

In the gasoline engine system according to the present embodiment, a variable valve timing mechanism 50 (hereinafter referred to as "VVT") driven by hydraulic pressure is used to change the opening / closing timing of the intake valve 21 (change of the valve overlap amount). Is provided.) This VVT
Reference numeral 50 denotes a mechanism for continuously changing the valve timing of the intake valve 21 by changing the phase of rotation of the intake side camshaft 23 with respect to the rotation of the crankshaft 14 (intake side timing pulley 27).

The system configuration of the VVT 50 will be described with reference to FIG. Here, FIG.
FIG. 5 is an explanatory diagram showing a cross section near the intake side camshaft 23 where 0 is disposed, and an entire control system of the VVT 50.

The control system of the VVT 50 includes a VVT 5
0, an oil control valve 80 (hereinafter referred to as “O”) constituting an actuator for applying a driving force to the VVT 50.
CV ". ), An OC angle sensor 44 for detecting a cam angle signal, various other sensors, and an OC based on input signals from various sensors including the cam angle sensor 44.
An electronic control unit (hereinafter, referred to as “ECU”) 70 for driving and controlling the V80 is provided.

The VVT 50 is disposed between the intake side camshaft 23 and the intake side timing pulley 27,
The intake camshaft 23 is rotatably supported between the cylinder head 12 and the bearing cap 51. An intake-side timing pulley 27 is mounted near the tip of the intake-side camshaft 23 so as to be relatively rotatable. An inner cap 52 is attached to the tip of the intake-side camshaft 23 by a hollow bolt 53 and a pin 54. It is attached so that it can rotate integrally.

A housing 56 having a cap 55 is provided on the intake side timing pulley 27 with bolts 57 and pins 5.
The housing 56 covers the distal end of the intake-side camshaft 23 and the entire inner cap 52. Further, on the outer periphery of the intake-side timing pulley 27, a number of external teeth 27a for mounting the timing belt 35 are formed.

The intake side camshaft 23 and the intake side timing pulley 27 are connected by a ring gear 59 interposed between the housing 56 and the inner cap 52. The ring gear 59 has a substantially annular shape, and is housed in a space S surrounded by the intake-side timing pulley 27, the housing 56, and the inner cap 52 so as to be able to reciprocate in the axial direction of the intake-side camshaft 23.
A large number of teeth 59a, 5
9b is formed.

Correspondingly, the outer periphery of the inner cap 52 and the inner periphery of the housing 56 have a number of teeth 52a,
6b are respectively formed. These teeth 59a, 5
9b, 52a, and 56b are helical teeth whose tooth traces intersect with the axis of the intake-side camshaft 23 at a predetermined angle. That is, the teeth 52a and the teeth 59a
Form a helical spline in which the teeth 56b and the teeth 59b are in mesh with each other. Then, by the engagement of these, the intake-side timing pulley 2
7, the housing 56 and the inner cap 52 are rotated.
Is transmitted to the intake side camshaft 23 through the Since the teeth 59a, 59b, 52a, and 56b are helical teeth, when the ring gear 59 moves in the axial direction of the intake-side camshaft 23, a twisting force is applied to the inner cap 52 and the housing 56, and the intake-side cam The shaft 23 moves relative to the intake-side timing pulley 27.

In the space S, a first hydraulic chamber 60 is formed at the front end of the ring gear 59 and a second hydraulic chamber 61 is formed at the rear end of the ring gear 59 in order to move the ring gear 59 in the axial direction. I have. The bearing cap 51 has a first hydraulic pressure supply hole 51a and a second hydraulic pressure supply hole 51b. Further, a first hydraulic pressure supply hole 51a and a first hydraulic chamber 6 are provided inside the intake side camshaft 23.
0 and a second hydraulic pressure supply passage 63 that connects the second hydraulic pressure supply hole 51b and the second hydraulic pressure chamber 61 are formed.

The lubricating oil sucked up from the oil pan 65 by the hydraulic pump 64 is supplied to each of the hydraulic supply holes 51a and 51b through the oil filter 66 at a predetermined pressure. In addition, each hydraulic supply path 62, 6
In order to selectively supply the hydraulic pressure to each of the hydraulic chambers 60 and 61 through the respective hydraulic pressure supply holes 51a and 51b, an OCV8 is provided.
0 is connected.

The OCV 80 is a four-port directional control valve for switching the flow direction of lubricating oil by causing a plunger 83 driven by an electromagnetic actuator 81 and a coil spring 82 to reciprocate a spool 84 in the axial direction. The duty of the electromagnetic actuator 81 is controlled, so that the opening is adjusted, and the magnitude of the hydraulic pressure supplied to the hydraulic chambers 60 and 61 is adjusted.

The casing 85 of the OCV 80 has a tank port 85t, an A port 85a, a B port 85b, and a reservoir port 85r. The tank port 85t is connected to the oil pan 65 via a hydraulic pump 64, and the A port 85a is connected to the first hydraulic supply hole 51.
a and the B port 85b are connected to the second hydraulic pressure supply holes 51b, respectively. The reservoir port 85r is connected to the oil pan 65.

The spool 84 is a cylindrical valve body.
It has four lands 84a for sealing the flow of the lubricating oil between the two ports, a passage 84b communicating between the two ports and allowing the flow of the lubricating oil, and two other passages 84c. .

In the VVT 50 having these configurations, OVT
When the drive of the CV 80 is controlled and the spool 84 is moved to the left in the drawing, the central passage 84b communicates the tank port 85t with the A port 85a, and lubricating oil is supplied to the first hydraulic supply hole 51a. . Then, the lubricating oil supplied to the first hydraulic pressure supply hole 51 a is supplied to the first hydraulic pressure chamber 60 via the first hydraulic pressure supply path 62, and the hydraulic pressure is applied to the distal end side of the ring gear 59.

At the same time, the passage 84c on the right side in FIG.
Communicates between the B port 85b and the reservoir port 85r, and the lubricating oil in the second hydraulic chamber 61 is supplied to the second hydraulic supply passage 6
3, the oil pan 6 via the second hydraulic pressure supply hole 51b, the B port 85b of the OCV 80, and the reservoir port 85r.
It is discharged to 5.

Accordingly, the ring gear 59 is moved while rotating to the rear end side (rightward in the drawing) by the hydraulic pressure applied to the front end side, and twist is given to the intake side camshaft 23 via the inner cap 52. . As a result, the rotation phase of the intake side camshaft 23 with respect to the intake side timing pulley 27 (crankshaft 14) is changed, and the intake side camshaft 23 rotates from the most retarded position to the most advanced position, and the intake valve 21 Is advanced (valve overlap amount is large).

The intake valve 21 whose valve opening timing has been advanced in this way is opened while the exhaust valve 31 is open, and the valve over which the intake valve 21 and the exhaust valve 31 are simultaneously opened. The lap amount is enlarged.
The movement of the ring gear 59 toward the rear end is regulated by the ring gear 59 abutting on the intake-side timing pulley 27. When the ring gear 59 abuts on the intake-side timing pulley 27 and stops, the intake valve 21 is stopped. The valve opening timing is the earliest.

On the other hand, when the drive of the OCV 80 is controlled and the spool 84 is moved rightward in the drawing, the central passage 84b communicates the tank port 85t with the B port 85b and lubricates the second hydraulic pressure supply hole 51b. Oil is supplied. Then, the lubricating oil supplied to the second hydraulic pressure supply hole 51b is supplied to the second hydraulic pressure chamber 61 via the second hydraulic pressure supply path 63,
Oil pressure is applied to the rear end side of the ring gear 59.

At the same time, the passage 84c on the left side in FIG.
Communicates the A port 85a with the reservoir port 85r, and the lubricating oil in the first hydraulic chamber 60
2. The oil pan 6 via the first hydraulic pressure supply hole 51a, the A port 85a of the OCV 80, and the reservoir port 85r.
It is discharged to 5.

Accordingly, the ring gear 59 is moved while rotating to the front end side (left side in the drawing) by the hydraulic pressure applied to the rear end side, and the intake camshaft 23 is twisted in the opposite direction via the inner cap 52. Granted. As a result,
Intake side timing pulley 27 (crankshaft 14)
, The rotation phase of the intake-side camshaft 23 is changed, the intake-side camshaft 23 rotates from the most advanced position to the most retarded position, and the opening timing of the intake valve 21 is retarded (valve overlap). Amount).

By delaying the valve opening timing of the intake valve 21 in this manner, the valve overlap amount at which the intake valve 21 and the exhaust valve 31 are simultaneously opened is reduced or set to zero. The movement of the ring gear 59 toward the distal end is regulated by the contact of the ring gear 59 with the housing 56. When the ring gear 59 contacts the housing 56 and stops, the valve opening timing of the intake valve 21 becomes the latest. .

The actual valve timing of the intake valve 21 changed by the VVT 50 is determined by the cam angle sensor 44.
Output from the cam angle signal and the crank angle sensor 40
And the crank angle signal output from the CPU. That is, the time required from the input of the cam angle signal to the ECU 70 until the input of the BTDC 30 ° crank angle signal (reference NE timing signal), for example, the engine speed NE, is measured, and the time is used as the displacement angle. By performing the conversion, the actual displacement angle of the intake camshaft 23 with respect to the crankshaft 14 is calculated.

Next, a control system of the valve timing control device VC for the internal combustion engine according to the present embodiment will be described with reference to a control block diagram shown in FIG. The control system of the valve timing control device VC of the internal combustion engine according to the present embodiment is configured with an electronic control device 70 (hereinafter, referred to as “ECU”) as a core. The ECU 70 constitutes target valve timing calculating means, deviation calculating means, control value calculating means, control means, holding control value learning means, learning update permission means, and the like.

The ECU 70 has a ROM 71 in which various control programs such as a VVT control program and a map for changing a valve timing corresponding to various conditions are stored. The ECU 70 executes a calculation process based on a control program stored in the ROM 71.
72, a RAM 73 for temporarily storing the result of calculation by the CPU 72, data input from each sensor, and the like, and a backup RAM 74 for holding various data stored in the RAM 73 when power supply is stopped. And C
PU72, ROM71, RAM73 and backup R
The AMs 74 are connected to each other via a bidirectional bus 75, and are also connected to an input interface 76 and an output interface 77.

The input interface 76 includes a crank angle sensor 40, an engine speed sensor 41, a cylinder discrimination sensor 42, a water temperature sensor 43, a cam angle sensor 44, a throttle sensor 45, a fully closed switch 46, and an intake pressure sensor 4.
7, an oxygen sensor 48, a starter switch 49 and the like are connected. When the signal output from each sensor or the like is an analog signal, the signal is converted into a digital signal by an A / D converter (not shown), and then converted into a digital signal.
5 is output. Further, external circuits such as the injector 17, the igniter 19, and the OCV 62 are connected to the output interface 77.
The operation is controlled based on the calculation result of the control program executed in U72.

Next, a variable valve timing (VVT) control program in the engine valve timing control device VC according to the present embodiment having the above configuration will be described with reference to flowcharts shown in FIGS.
That is, the flowcharts shown in FIGS. 4 to 6 show a “hold duty value learning control routine” executed by the ECU 70 to calculate the control duty value Uk and learn the hold duty value DA. It is executed by interruption every predetermined crank angle.

When the processing shifts to this routine, the ECU
First, in step 101 (see FIG. 4), signals indicating various operating states are read based on detection signals from various sensors and the like.

Next, in step 102, based on the cam angle signal output from the cam angle sensor 44 and the crank angle signal output from the crank angle sensor 40, an actual camshaft advance value (hereinafter referred to as " (Referred to as "actual advance value"). In step 103, a target camshaft advance value (hereinafter, referred to as "target advance value") VTT is calculated based on the current operation state.

Further, in the following step 104,
A value obtained by subtracting the actual advance value VTB read this time from the target advance value VTT calculated this time is set as the deviation Ek. Then, in step 105, the ECU 70 compares the deviation Ek calculated this time with “0”. If the deviation Ek is equal to or greater than "0", the process proceeds to step 106.

At step 106, the ECU 70
In order to set the valve timing to the advanced side, the following equation (1) is used.
The control duty value Uk is calculated according to: Uk = Kp1 * Ek + Kd1 (Ek-Eki _-1 ) + DA (1) where Kp1 and Kd1 are feedback gains. Eki _-1 is the previous deviation Ek.

On the other hand, in step 105, the deviation Ek
Is negative, the process proceeds to step 107. In step 107, the ECU 70 calculates the control duty value Uk according to the following equation (2) in order to set the valve timing to the retard side.

Uk = Kp2 * Ek + Kd2 (Ek−Eki ₋₁ ) + DA (2) where Kp2 and Kd2 are feedback gains. In the present embodiment, the above equations (1) and (2)
The feedback gain is set to a different value between (2), but the same value may be used. The calculated control duty value Uk is used as a control signal as an OC signal.
Output to V80 (linear solenoid).

Now, step 106 or step 107
In step 108, the ECU 70
Determines whether the starter signal STA is on. If the starter signal STA is on, it is determined that the current time is the starting time, and the process proceeds to step 109. In step 109, the learned RAM 73
Is set as the holding duty value DA, and the holding duty learning value DAM is set as the holding duty value DA (i) used in the current calculation. And the ECU 7
0 ends the subsequent processing once.

If the starter signal STA is off in step 108, it is determined that the current time is not the start, and the process proceeds to step 110. In step 110, it is determined whether or not the current cooling water temperature THW is equal to or higher than a predetermined value α2 (see FIG. 7). Here, the predetermined value α2 is a value that serves as a boundary for determining whether or not a cold state is present. Then, the current cooling water temperature TH
If W is less than the predetermined value α2, the ECU 70 determines that the present time is a cold state, and shifts to step 109 as described above. That is, the held duty learning value DAM learned and stored in the RAM 73 is replaced with the held duty value D
A and hold duty learning value DA
M is the holding duty value DA used in the current calculation.
Set as (i). Then, the ECU 70 once ends the subsequent processing.

On the other hand, if the current cooling water temperature THW is equal to or higher than the predetermined value α2, the ECU 70 determines that the current time is neither the start time nor the cold time, and shifts to step 111 (see FIG. 5). I do. In step 111, the ECU
70 indicates that a later-described reference setting flag XKIJUN is “1”
Is determined. Then, the reference setting flag XK
If IJUN is not "1", that is, if it is "0", the process proceeds to step 112 (see FIG. 6) in order to set reference values (actual reference value YA, target reference value RA) for learning condition satisfaction determination. .

In step 112, the ECU 70
The current target advance value VTT is input to the target reference value RA, and the current actual advance value VTB is input to the actual reference value YA. Also, along with this, the reference setting flag XKIJUN
Is set to “1”.

Further, in the next step 113, the count value C1 of the counter is cleared to "0", and in the following step 114, the learning flag XGKS for determining the satisfaction of the learning condition is set to "0". further,
In step 115, the ECU 70 determines that the current RAM 7
3 is a storage value Uk of the control duty value Uk stored in
M is deleted. Then, the subsequent processing ends once.

On the other hand, if it is determined in step 111 (see FIG. 5) that the reference setting flag XKIJUN is "1", the process proceeds to step 116. In step 116, the ECU 70 determines whether or not the learning flag XGKS is currently set to "1". If the learning flag XGKS is not set to “1”, that is, if the learning flag XGKS is “0”, the process proceeds to step 117.

In step 117, the ECU 70
It is determined whether or not the target advance value VTT is substantially constant.
That is, it is determined whether or not the variation range of the target advance value VTT with respect to the target reference value RA is within the small range ΔR. If the target advance value VTT is not substantially constant, the process returns to step 112 again, where the target reference value RA,
The input of the actual reference value YA and the like are redone (steps 112 to 115).

On the other hand, if the target advance value VTT is substantially constant, the routine proceeds to step 118. In step 118, it is determined whether or not the actual reference value YA is substantially constant. That is, it is determined whether or not the variation range of the actual advance angle value VTB with respect to the actual reference value YA is within the minute range ΔY. Then, even when the actual advance value VTB is not substantially constant, the flow shifts to step 112 again, and the input of the target reference value RA, the actual reference value YA, etc. is performed again (step 1).
12 to Step 115). If the actual advance value VTB is substantially constant, the process proceeds to step 119 to execute the learning control of the holding duty DA.

In step 119, the count value C1 of the above-described counter is set to a predetermined time T1.
It is determined whether or not the above has been achieved. And the count value C
If 1 is not equal to or longer than the predetermined time T1, the subsequent processing is temporarily terminated without performing any processing. On the other hand, when the count value C1 is equal to or longer than the predetermined time T1, the process proceeds to step 120.

In step 120, the ECU 70
The learning flag XGKS is set to "1", and in the following step 121, the current control duty value U
k is set as the stored value UkM. Further, in the next step 122, the count value C2 of the counter is set to "0".
And the subsequent processing is once ended.

If the learning flag XGKS is "1" in step 116, the process proceeds to step 123.
Move to. In step 123, the actual reference value YA
Is again determined whether or not is substantially constant. That is, it is determined whether or not the variation range of the actual advance angle value VTB with respect to the actual reference value YA is within the minute range ΔY. And the actual advance angle value V
If TB is not substantially constant, step 11 described above is repeated.
Then, the process returns to step 2 to re-input the target reference value RA and the actual reference value YA (steps 112 to 115). Also,
When the actual advance angle value VTB is substantially constant, the actual advance angle value Vk can be obtained by using the stored control duty value Uk (stored value UkM).
If it is confirmed that the TB hardly changes, the process proceeds to step 124. In step 124, it is determined whether or not the count value C2 of the counter has exceeded a predetermined time T2. And the count value C2
If has not reached the predetermined time T2 or more, the subsequent processing is temporarily terminated. On the other hand, the count value C2
Is equal to or longer than the predetermined time T2, it is determined that the actual advance value VTB remains substantially the same for the predetermined time (T2) even if the stored value UkM is used, and the routine proceeds to step 125.

In step 125, the stored value UkM currently stored is set as the holding duty value DA. In the next step 126, it is determined whether or not the current cooling water temperature THW is equal to or higher than a predetermined value α4. Here, the cooling water temperature THW is a predetermined value α4
The above means that the engine 10 is in a completely warmed-up state, and also, as shown in FIG. 7, that the holding duty value DA is at or above a considerable level. When the current cooling water temperature THW is less than the predetermined value α4, it is determined that it is not appropriate to store the holding duty value DA for the next start or for the time of cold,
Thereafter, the processing is temporarily terminated. On the other hand, if the current cooling water temperature THW is equal to or higher than the predetermined value α4, the ECU 70 determines in step 127 that the current cooling water temperature THW is equal to or smaller than the predetermined value α4 in order to store the holding duty value DA for the next start or during the cold period. The holding duty value DA is used as the holding duty learning value DAM.
Set as Further, in the following step 128, the ECU 70 sets the reference setting flag XKIJUN to “0” in order to end the learning control. Then, the subsequent processing ends once.

As described above, in the "hold duty value learning control routine", the control duty value is determined based on the deviation Ek between the current target advance value VTT and the actual advance value VTB and the hold duty value DA. Uk is calculated. At the same time, the holding duty value DA is learned and updated under a predetermined condition for the next start or for a cold time.

Next, the operation and effect of this embodiment will be described. In the present embodiment, during operation of the engine 10,
The holding duty value DA is updated as appropriate. For this reason, the holding duty value DA inherently can fluctuate due to a manufacturing tolerance of the OCV 80, a change over time, or the like. However, by performing the learning update, the holding duty value DA is optimized.

Further, when the engine 10 is started or when it is cold, the holding duty value DA is set to the holding duty learning value DAM learned in advance. By the way, FIG.
, The actual holding duty value DA with respect to the temperature of the engine 10 (for example, oil temperature or cooling water temperature THW) is
The relationship is high on the low temperature side and high temperature side, and low on the intermediate region. On the other hand, in the present embodiment, the engine 10
The learning update of the holding duty learning value DAM is permitted only when the temperature of the cooling water temperature THW is equal to or higher than the predetermined temperature, that is, only when the cooling water temperature THW is equal to or higher than the predetermined value α4.

For this reason, the hold duty learning value D which is equal to or larger than the predetermined value α4, that is, the learning update is allowed only on the high temperature side.
AM does not significantly differ from the actual holding duty value DA on the low temperature side at the next start (or at the time of cold). For example, in the figure, if learning is performed at the time when the cooling water temperature THW corresponds to the predetermined value α4, the holding duty value DA (holding duty learning value DAM) is “β2”, while the holding duty value DA is “β2”. The cooling water temperature THW is equal to a predetermined value α.
Actual holding duty value DA at the time corresponding to 1
Is “β3”, and the difference is as small as ΔDA2.
Therefore, the holding duty value DA used at the next start or at the time of cold can be substantially appropriate.

Therefore, it is possible to prevent the occurrence of a valve timing control error (error on the retard side). As a result, it is possible to reliably prevent the engine 10 from being adversely affected by insufficient torque and, consequently, poor acceleration due to insufficient valve timing advance.

In particular, the predetermined value α4 is determined by the engine 10
Is completely warmed up, one condition is satisfied. For this reason, the above-described operation and effect can be more reliably achieved.

Further, in the present embodiment, the learning control is performed only when both the target advance value VTT and the actual advance value VTB are substantially constant. For this reason, it is possible to improve learning accuracy by breaking erroneous learning.

The present invention is not limited to the above-described embodiment, but may be implemented as follows with a part of the configuration appropriately changed without departing from the spirit of the invention. (1) Although not particularly mentioned in the above embodiment, the predetermined values α2 and α4 may be made variable according to the engine speed NE and the like. This is in consideration of the fact that the characteristic of the holding duty value DA as shown in FIG. 7 can fluctuate also according to the engine speed NE. Accordingly, by making the predetermined values α2 and α4 variable as described above, it is possible to further improve controllability.

(2) In the above embodiment, the cooling water temperature THW is employed as a parameter for determining whether or not the learning update of the holding duty value DA is permitted.
Other parameters (for example, oil temperature, etc.) may be adopted as long as they are parameters corresponding to the temperature of (1).

(3) In the above embodiment, the variable valve timing mechanism employs the VVT 50 of the type in which the ring gear 59 moves.
(For example, a vane type VVT) may be adopted.

(4) In the above embodiment, the valve timing control of a gasoline engine as an engine has been embodied, but it may be embodied in a diesel engine.

[0087]

As described in detail above, according to the present invention,
The control value is calculated based on the holding control value, and in the valve timing control of the engine that controls the variable valve timing mechanism based on the control value, it is possible to obtain an appropriate holding control value at the time of starting or at the time of cold. Therefore, an excellent effect that an adverse effect on the engine such as poor acceleration can be prevented is achieved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an engine valve timing control device according to an embodiment.

FIG. 2 is a schematic configuration diagram showing a configuration of a VVT, an OCV, and the like.

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

FIG. 4 is a flowchart showing a “hold duty value learning control routine” executed by the ECU.

FIG. 5 is a continuation of FIG. 4 and is a flowchart showing a “hold duty value learning control routine”;

FIG. 6 is a continuation of FIG. 5, showing a “hold duty value learning control routine”;

FIG. 7 is a graph showing characteristics of a holding duty value with respect to a cooling water temperature (or an oil temperature).

[Explanation of symbols]

Reference numeral 10: engine, 15: combustion chamber, 20: intake passage, 21
... intake valve, 30 ... exhaust passage, 40 ... crank angle sensor, 41 ... engine speed sensor, 42 ... cylinder discrimination sensor, 43 ... water temperature sensor, 44 ... cam angle sensor, 45 ... throttle sensor, 46 ... fully closed switch, 47: intake pressure sensor, 48: oxygen sensor, 49: starter switch (each of the sensors 41 to 49 constitutes operating state detecting means. Sensors such as 44 and 40 constitute actual valve timing detecting means. , 50... VVT, 70
... ECU which constitutes target valve timing calculation means, deviation calculation means, control value calculation means, control means, holding control value learning means, learning update permission means, etc.

Claims (3)

[Claims] 1. An intake valve and an exhaust valve which are driven at predetermined timings in synchronization with a crankshaft of an engine to open and close an intake passage and an exhaust passage respectively leading to a combustion chamber, and at least one of the intake valve and the exhaust valve. A variable valve timing mechanism for changing one of the valve timings; an actuator for driving the variable valve timing mechanism; an operating state detecting means for detecting an operating state of the engine; and a detection result of the operating state detecting means. Target valve timing calculating means for calculating a target value of the valve timing changed by the variable valve timing mechanism; actual valve timing detecting means for detecting an actual valve timing changed by the variable valve timing mechanism; Valve timing Deviation calculating means for calculating a deviation between the target value calculated by the torque calculating means and the actual valve timing detected by the actual valve timing detecting means; and a deviation calculated by at least the deviation calculating means; A control value calculating unit that calculates a control value based on a holding control value for maintaining the advance amount of the variable valve timing mechanism at a constant amount, based on the control value calculated by the control value calculating unit, Control means for controlling the variable valve timing mechanism by controlling an actuator, and a holding control value learning means for learning and updating the holding control value during operation of the engine; and A variable valve timing control device for an engine, wherein a holding control learning value learned by a learning means is used as a holding control value, A variable valve timing control device for an engine, further comprising: a learning update permitting means for permitting a learning update of the holding control value learning means only when the temperature of the engine is equal to or higher than a predetermined temperature. 2. The engine variable valve timing control device according to claim 1, wherein the predetermined temperature or more is satisfied when the engine is completely warmed up. Variable valve timing control device. 3. The variable valve timing control device for an engine according to claim 1, wherein the actuator is an oil control valve that is duty-controlled to adjust a control oil pressure supplied to the variable valve timing mechanism. A variable valve timing control device for an engine.