JP4387633B2 - Engine valve timing control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine valve timing control apparatus having a hydraulically driven variable valve timing mechanism that adjusts a rotational phase between a crankshaft and a camshaft of an engine, and more particularly, to cleaning a hydraulic system under a predetermined condition. The present invention relates to an engine valve timing control apparatus.
[0002]
[Prior art]
In recent years, an engine having a variable valve timing mechanism that adjusts the rotational phase between the crankshaft and the camshaft of the engine has been put into practical use. The variable valve timing mechanism is controlled to continuously change the valve timing of at least one of the intake valve and the exhaust valve.
[0003]
Here, the variable valve timing mechanism generally employs a hydraulic drive type driven by hydraulic pressure, but the oil supplied to the variable valve timing mechanism has impurities due to deterioration over time of use or during cutting. Foreign matter such as fine swarf floats and impurities and foreign matter in the oil easily settle and accumulate when the amount of circulating oil in the hydraulic system is small. Sliding parts such as variable valve timing mechanisms and hydraulic control valves This may cause malfunction due to deterioration of slidability and biting of foreign matter.
[0004]
For this reason, conventionally, the operating amount of the variable valve timing mechanism is forcibly increased under a predetermined condition as compared with the control to the normal target valve timing to increase the circulating oil amount, and the variable valve timing mechanism and the hydraulic control valve The sliding portion and the oil passage are cleaned, and Japanese Patent No. 3098676 discloses that foreign matter is caught in the hydraulic control valve based on the phase shift between the actual cam phase and the target cam phase. Discloses a technique for performing a cleaning operation by changing the amount of movement of the valve body for a predetermined time so as to increase the opening amount of the hydraulic control valve when it is determined that the oil is caught.
[0005]
[Problems to be solved by the invention]
However, performing the cleaning operation based on the phase shift between the actual cam phase and the target cam phase, as in the prior art, directly captures the operating state of the mechanism parts such as the valve timing mechanism and the hydraulic control valve. However, the overall state including other factors of the system is regarded as the operating state of the valve timing mechanism and the hydraulic control valve mechanism, so it is not always the best judgment for the cleaning operation. Not a standard.
[0006]
The present invention has been made in view of the above circumstances, and provides an engine valve timing control device that can optimize the execution judgment criteria of a cleaning operation of a variable valve timing mechanism and improve the effectiveness of the cleaning operation. It is aimed.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 controls a hydraulically driven variable valve timing mechanism that adjusts a rotational phase between a crankshaft and a camshaft of an engine in accordance with an engine operating state. In a valve timing control device for an engine that forcibly increases the operation amount of the variable valve timing mechanism when a condition is satisfied to perform a cleaning operation of the hydraulic system, the control amount for the hydraulic control valve that controls the hydraulic pressure of the variable valve timing mechanism But Based on feedback controlled variable by proportional derivative control It is checked whether or not it is within the set range. If the time during which the control amount is outside the set range continues for a set time or longer, means for determining that the execution condition for the cleaning operation is satisfied, and the execution condition for the cleaning operation is satisfied And a means for operating the variable valve timing mechanism at the most advanced position and the most retarded position by a full stroke.
[0008]
According to a second aspect of the present invention, in the first aspect of the present invention, the setting range is different for each engine speed region. For the feedback control amount The minimum value of the upper limit regulation value is set corresponding to a value obtained by adding or subtracting from a learning value of a control amount for holding the variable valve timing mechanism in a steady state at a predetermined cam phase.
[0009]
That is, according to the first aspect of the present invention, the control amount for the hydraulic control valve that controls the hydraulic pressure of the hydraulically driven variable valve timing mechanism that adjusts the rotational phase between the crankshaft and the camshaft of the engine is small. Based on feedback controlled variable by proportional derivative control If the time outside the setting range continues for more than the set time, it is determined that the conditions for performing the cleaning operation for cleaning the hydraulic system by forcibly increasing the operating amount of the variable valve timing mechanism are satisfied, and the variable valve timing mechanism is By operating the full stroke at the advance angle position and the most retarded angle position, it is possible to optimize the cleaning operation execution criterion, grasp the actual operation state of the mechanical system, and improve the effectiveness of the cleaning operation.
[0010]
At that time, as in the invention described in claim 2, the engine rotation is determined from the learning value of the control amount for maintaining the variable valve timing mechanism in a steady state at a predetermined cam phase. Every few regions For feedback control amount It is desirable to set the value corresponding to the value obtained by adding or subtracting the minimum value of the upper limit regulation value. By reflecting the learning value and the actual control amount that differ depending on the individual mechanism system, the operation state of the mechanism system can be handled more reliably. Thus, the cleaning operation can be performed.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. 1 to 6 relate to an embodiment of the present invention, FIG. 1 is an overall configuration diagram of an engine with a variable valve timing mechanism, FIG. 2 is a schematic configuration diagram of a variable valve timing mechanism, and FIG. FIG. 4 is an explanatory diagram showing the most advanced state in the AA section of FIG. 2, FIG. 4 is an explanatory view showing the most retarded state of the variable valve timing mechanism in the AA section of FIG. 2, and FIG. FIG. 6 is a block diagram of the valve timing control routine.
[0012]
First, the overall configuration of an engine with a variable valve timing mechanism to which the present invention is applied will be described with reference to FIG. In the figure, reference numeral 1 denotes an engine with a variable valve timing mechanism (hereinafter simply abbreviated as “engine”). In the figure, a DOHC horizontally opposed four-cylinder gasoline engine is shown. Cylinder heads 2 are provided in both the left and right banks of the cylinder block 1a of the engine 1, and an intake port 2a and an exhaust port 2b are formed in each cylinder head 2 for each cylinder.
[0013]
As an intake system of the engine 1, an intake manifold 3 is communicated with each intake port 2 a, and a throttle valve 5 a that is linked to an accelerator pedal is connected to the intake manifold 3 through an air chamber 4 in which an intake passage of each cylinder is gathered. The mounted throttle chamber 5 is communicated. An air cleaner 7 is attached upstream of the throttle chamber 5 via an intake pipe 6, and a chamber 8 is communicated with an air intake passage connected to the air cleaner 7.
[0014]
Further, a bypass passage 9 that bypasses the throttle valve 5a is connected to the intake pipe 6. By adjusting the amount of bypass air flowing through the bypass passage 9 according to the opening of the bypass passage 9 during idling. An idle control valve 10 for controlling the idle speed is interposed.
[0015]
Further, an injector 11 is disposed immediately upstream of the intake port 2 a of each cylinder of the intake manifold 3. A spark plug 12 that exposes the discharge electrode at the tip to the combustion chamber is provided in the cylinder head 2 for each cylinder. Each spark plug 12 is connected to an ignition coil 13 with a built-in igniter.
[0016]
On the other hand, as an exhaust system of the engine 1, an exhaust pipe 15 is communicated with a collective portion of the exhaust manifold 14 communicating with each exhaust port 2 b of the cylinder head 2, and a catalyst converter 16 is interposed in the exhaust pipe 15 and a muffler 17. It is communicated to.
[0017]
Here, the variable valve timing mechanism of the engine 1 will be described with reference to FIGS.
[0018]
The rotation of the crankshaft 18 of the engine 1 is caused by the crank pulley 21 fixed to the crankshaft 18 and the timing of the intake camshaft 19 and the exhaust camshaft 20 respectively disposed in the cylinder heads 2 of the left and right banks. The transmission is transmitted via the belt 22, the intake cam pulley 23 provided on the intake cam shaft 19, the exhaust cam pulley 24 fixed to the exhaust cam shaft 20, and the crankshaft 18 and the cam shafts 19 and 20 are in a two-to-one relationship. The rotation angle is set. A cam 19a provided on the intake camshaft 19 and an exhaust cam (not shown) provided on the exhaust camshaft 20 are respectively maintained at a rotation angle of 2: 1 with the crankshaft 18. , 20 is driven to open and close the intake valve 25 and the exhaust valve 26.
[0019]
As shown in FIG. 2, between the intake cam shafts 19 and the intake cam pulleys 23 of the left and right banks, the intake cam pulleys 23 and the intake cam shafts 19 are relatively rotated to rotate the intake cam shaft 19 with respect to the crankshaft 18. A hydraulically driven variable valve timing mechanism 27 for continuously changing the phase (displacement angle) is provided. As is well known, the variable valve timing mechanism 27 has its hydraulic pressure switched by an oil flow control valve 36R (36L) composed of a linear solenoid valve or a duty solenoid valve, and an electronic control unit 60 (see FIG. 5) described later. ) By the drive signal from Note that the subscript R in the reference numeral represents the right bank, and L represents the left bank.
[0020]
The intake camshaft 19 is rotatably supported between the cylinder head 2 and a bearing cap (not shown), and has three vanes 28a at the tip of the intake camshaft 19 as shown in FIGS. A vane rotor 28 is attached by bolts 29 so as to be integrally rotatable.
[0021]
A housing 30 and a housing cover 31 are attached to the intake cam pulley 23 by bolts 32 so as to be integrally rotatable. In addition, on the outer periphery of the intake cam pulley 23, many external teeth 23a for hooking the timing belt 22 are formed.
[0022]
Then, the intake cam shaft 19 passes through the housing cover 31 so as to be rotatable, and each vane 28a of the vane rotor 28 fixed to the intake cam shaft 19 is formed in three fan-shaped spaces formed in the housing 30 integral with the intake cam pulley 23. The part 33 is stored in a freely rotatable manner. Each fan-shaped space 33 is partitioned into an advance chamber 33a and a retard chamber 33b by vanes 28a.
[0023]
The advance chamber 33a is communicated with the A port 36a of the oil flow control valve 36R (36L) via the advance side oil passages 28b, 19b, 34 formed in the vane rotor 28, the intake camshaft 19, and the cylinder head 2, respectively. The retard chamber 33b is connected to the B port 36b of the oil flow control valve 36R (36L) via the retard angle side oil passages 28c, 19c, 35 formed in the vane rotor 28, the intake camshaft 19, and the cylinder head 2, respectively. It is communicated to.
[0024]
The oil flow control valve 36R (36L) includes an oil supply port 36c connected to an oil supply passage 40 to which oil, that is, a predetermined hydraulic pressure is supplied from an oil pan 37 through an oil pump 38 and an oil filter 39, and two drain passages. A spool 36g having drain ports 36d and 36f communicating with 41 and 42, respectively, and having four lands and three passages formed between the lands is reciprocated in the axial direction, whereby A ports 36a and B The port 36b is selectively communicated with the oil supply port 36c and the drain port 36d or 36f.
[0025]
In this embodiment, the oil flow control valve 36R (36L) is a four-way control valve whose energization current is controlled by a duty signal from an electronic control device 60 described later, and the spool 36g is axially proportional to the energization current. The flow direction of oil is switched and the opening degree of the passage is adjusted, and the hydraulic pressure supplied to each advance chamber 33a and retard chamber 33b is adjusted.
[0026]
Reference numeral 28d denotes a stopper pin inserted into the vane 28a of the vane rotor 28, and engages with a hole 30a formed in the housing 30 when the variable valve timing mechanism 27 is in the most retarded state (see FIG. 4). Position. The most retarded position of the variable valve timing mechanism 27 due to this mechanical engagement is determined by the rotational phase (displacement) of the intake camshaft 19 relative to the crankshaft 18 which is calculated based on a signal from a sensor in an electronic control device 60 described later. The reference position for calibrating the angle) is learned, and a deviation from the actual displacement angle (actual valve timing) of the intake camshaft 19 calculated from the sensor value at this reference position is learned. 3 shows the most advanced angle state of the variable valve timing mechanism 27, and FIG. 4 shows the most retarded angle state of the variable valve timing mechanism 27.
[0027]
In the variable valve timing mechanism 27 described above, projections (detected portions) provided at predetermined crank angles on the outer periphery of the crank rotor 43 that is attached to the crankshaft 18 and rotates synchronously as a sensor for detecting the operating position thereof. And a plurality of protrusions provided at equal angles on the outer periphery of a cam rotor 45 that is fixed to the rear end of the intake camshaft 19 and rotates in synchronization with the crank angle sensor 44 that outputs a crank pulse representing the crank angle. A cam position sensor 46R (46L) that detects a detected portion) and outputs a cam position pulse representing the cam position is used.
[0028]
The crank pulse output from the crank angle sensor 44 and the cam position pulse output from the cam position sensor 46R (46L) are input to the electronic control unit 60. The electronic control unit 60 calculates the actual displacement angle (actual valve timing) of the intake cam position with respect to the reference crank angle based on the crank pulse and the cam position pulse, and the actual valve timing is set based on the engine operating state. The variable valve timing mechanism 27 is feedback controlled so as to converge to the timing.
[0029]
In this embodiment, the variable valve timing mechanism 27 is provided only on the intake camshaft 19 side, and the opening / closing timing of the intake valve 25 is changed according to the engine operating state with respect to the opening / closing timing of the exhaust valve 26. In this embodiment, the oil flow control valve 36R (36L) has a larger energization current value as the duty ratio of the control signal output from the electronic control device 60 is larger, and the spool 36g is left as shown in FIG. The angle of movement of the intake camshaft 19 relative to the crankshaft 18 is advanced, and the smaller the duty ratio of the control signal, the smaller the energization current value and the spool 36g moves to the right as shown in FIG. Thus, the displacement angle of the intake camshaft 19 with respect to the crankshaft 18 is retarded.
[0030]
Next, sensors for detecting the engine operating state will be described. A thermal intake air amount sensor 47 using a hot wire or a hot film is provided immediately downstream of the air cleaner 7 of the intake pipe 6, and a throttle opening sensor is connected to a throttle valve 5 a provided in the throttle chamber 5. 48 is continuously provided.
[0031]
Further, a knock sensor 49 is attached to the cylinder block 1a of the engine 1, and a cooling water temperature sensor 51 is exposed in a cooling water passage 50 that communicates both the left and right banks of the cylinder block 1a. Further, an O2 sensor 52 is disposed upstream of the catalytic converter 16. The aforementioned crank angle sensor 44 is provided on the outer periphery of the crank rotor 43 that is axially attached to the crankshaft 18 of the engine 1, and a cylinder discrimination sensor 53 is provided on the back surface of the intake cam pulley 23 that rotates 1/2 with respect to the crankshaft 18. (See FIG. 2), and the cam position sensor 46R (46L) described above is provided on the outer periphery of the cam rotor 45 fixed to the rear end of the intake camshaft 19.
[0032]
The output signals of the above sensors are processed in an electronic control unit (hereinafter abbreviated as “ECU”) 60 shown in FIG. The ECU 60 includes oil flow control valves 36R and 36L for adjusting the hydraulic pressure supplied to the injector 11, the spark plug 12, the idle control valve 10, and the variable valve timing mechanism 27 based on signals from the sensors. It performs control amount calculation for actuators, output of control signals, that is, fuel injection control, ignition timing control, idle speed control, valve timing control for intake valve 25, and the like. CPU 61, ROM 62, RAM 63, backup RAM 64 The counter / timer group 65 and the I / O interface 66 are configured around a microcomputer connected via a bus line, and are connected to a constant voltage circuit 67 and a I / O interface 66 for supplying a stabilized power to each part. Drive circuit 68, A / D converter Peripheral circuits such as 9 have been built.
[0033]
The constant voltage circuit 67 is connected to the battery 71 via a first relay contact of a power relay 70 having two relay contacts. The power relay 70 has one end of its relay coil grounded and the other end of the relay coil. Is connected to the drive circuit 68. A power supply line for supplying power from the battery 71 to each actuator is connected to the second relay contact of the power supply relay 70. One end of an ignition switch 72 is connected to the battery 71, and the other end of the ignition switch 72 is connected to an input port of the I / O interface 66.
[0034]
Further, the constant voltage circuit 67 is directly connected to the battery 71. When the ignition switch 72 is detected to be ON and the contact of the power relay 70 is closed, the constant voltage circuit 67 supplies power to each part in the ECU 60, while the ignition switch 72 is turned on. Regardless of whether 72 is ON or OFF, the backup RAM 64 is always supplied with backup power.
[0035]
The input port of the I / O interface 66 includes a knock sensor 49, a crank angle sensor 44, a cylinder discrimination sensor 53, a right bank (RH) cam position sensor 46R, a left bank (LH) cam position sensor 46L, and a vehicle speed. A vehicle speed sensor 54 is connected, and an intake air amount sensor 47, a throttle opening sensor 48, a coolant temperature sensor 51, and an O2 sensor 52 are connected via an A / D converter 69. The battery voltage VB is input and monitored.
[0036]
On the other hand, to the output port of the I / O interface 66, the idle control valve 10, the injector 11, the oil flow control valves 36R and 36L, and the relay coil of the power relay 70 are connected via a drive circuit 68, and an igniter. An igniter 13a of the built-in ignition coil 13 is connected.
[0037]
In the ECU 60, in accordance with a control program stored in the ROM 62, the CPU 61 processes the detection signals from the sensors / switches and the battery voltage input via the I / O interface 66, and stores various data stored in the RAM 63. , Based on various learning value data stored in the backup RAM 64 and fixed data stored in the ROM 62, the fuel injection amount, the ignition timing, the duty ratio of the control signal for the idle control valve 10, the oil flow control valve 36R, The engine control such as fuel injection control, ignition timing control, idle speed control, and valve timing control is performed by calculating the duty ratio of the control signal for 36L.
[0038]
Here, as described above, the valve timing control by the variable valve timing mechanism 27 is based on the crank pulse output from the crank angle sensor 44 and the cam position pulse output from the cam position sensor 46R (46L). The rotational phase of the intake cam position with respect to the reference crank angle, that is, the actual displacement angle (actual valve timing) of the intake cam shaft 19 with respect to the crankshaft 18 is calculated, and this actual valve timing is set to the target valve timing set based on the engine operating state. The control current values of the oil flow control valves 36R and 36L are calculated so as to converge, and a duty signal that gives this control current value is output to the oil flow control valves 36R and 36L to feedback control the variable valve timing mechanism 27.
[0039]
At that time, the ECU 60 causes deterioration in slidability in sliding portions such as the vane rotor 28 of the variable valve timing mechanism 27 and the spool 36g of the oil flow control valve 36R (36L) due to accumulation and precipitation of impurities and foreign matters in the oil. In order to prevent foreign matter from getting caught, the operation amount of the variable valve timing mechanism 27 is forcibly increased to appropriately perform the operation in the cleaning mode for cleaning the hydraulic system.
[0040]
Whether or not to perform the cleaning mode operation is determined by checking an actual control duty of the oil flow control valve 36R (36L) in which the valve timing mechanism 27 is operating. That is, it is checked whether or not the control duty of the oil flow control valve 36R (36L) is within a setting range that guarantees normal operation of the valve timing mechanism 27, and the state where the control duty is outside the setting range has continued for a set time or more. In this case, it is determined that the execution condition for the cleaning operation is satisfied.
[0041]
Hereinafter, processing related to valve timing control by the ECU 60 will be described with reference to a flowchart of a valve timing control routine shown in FIG.
[0042]
FIG. 6 is a routine that is executed every predetermined time after the ignition switch 72 is turned on, the ECU 60 is powered on, and the system is initialized. First, in step S101, normal control of valve timing is executed. . In the normal control of the valve timing, the oil flow control valves 36R and 36L are operated so that the actual displacement angle (actual valve timing) of the intake cam shaft 19 with respect to the crankshaft 18 converges to the target valve timing set based on the engine operating state. Feedback control.
[0043]
The current value of the oil flow control valve 36R (36L) at this time is obtained by adding or subtracting the feedback current value by proportional differential control (PD control) according to the deviation between the target valve timing and the actual valve timing to the holding current value described below. It is calculated as the value obtained. The holding current value is such that the spool 36g of the oil flow control valve 36R (36L) is held at a position where the A port 36a and the B port 36b are closed by the land, and the advance side oil passage 34 on the cylinder head 2 side. By closing the retard side oil passage 35 from the oil supply port 36c and drain ports 36d and 36f of the oil flow control valve 36L (36R), the vane rotor 28 of the variable valve timing mechanism 27 is also retarded to the advance side. This is a current value for maintaining a steady state converged at a predetermined target valve timing without being displaced to the side (with a moving speed of 0), and is learned for each individual engine oil flow control valve 36R (36L). The
[0044]
That is, the current value of the oil flow control valve 36R (36L) is increased / decreased by the feedback current value corresponding to the deviation between the target valve timing and the actual valve timing, with respect to the holding current value that is different for each individual, and the stroke of the spool 36g is increased. Variable. Due to the change in the stroke, the amount of connection between the advance side oil passage 34 or the retard side oil passage 35 and the oil supply passage 40, and the advance angle side oil passage 34 or the retard side oil passage 35 and the drain passages 41 and 42 are changed. The amount of connection is changed between 0 and 100%, and feedback control is performed so that the actual valve timing converges to the target valve timing.
[0045]
When the actual valve timing is retarded with respect to the target valve timing, the control duty dVVT output to the oil flow control valve 36R (36L) is increased to increase the current value. The spool 36g is moved in a direction in which the amount of connection between the oil supply passage 40 and the amount of connection between the retarded-side oil passage 35 and the drain passage 42 increases. As a result, the hydraulic pressure in the advance chamber 33a of the variable valve timing mechanism 27 increases and the hydraulic pressure in the retard chamber 33b decreases, and the vane rotor 28 rotates in the clockwise direction (see FIG. 3). The rotational phase of the camshaft 19, that is, the rotational phase (displacement angle) of the intake camshaft 19 relative to the crankshaft 18 is advanced, and the opening / closing timing of the intake valve 25 driven by the intake cam 19 a of the intake camshaft 19 is advanced. The
[0046]
Conversely, when the actual valve timing is advanced with respect to the target valve timing, the control duty dVVT output to the oil flow control valve 36R (36L) is decreased to decrease the current value, and the retarded side oil The spool 36g is moved in a direction in which the connection amount between the passage 35 and the oil supply passage 40 and the connection amount between the advance side oil passage 34 and the drain passage 41 are increased. As a result, the hydraulic pressure in the advance chamber 33a of the advance chamber 33a of the variable valve timing mechanism 27 decreases and the hydraulic pressure in the retard chamber 33b increases, and the vane rotor 28 rotates counterclockwise (see FIG. 4). The rotational phase of the intake camshaft 19 relative to the intake cam pulley 23, that is, the rotational phase (displacement angle) of the intake camshaft 19 relative to the crankshaft 18 is retarded, and the intake valve 25 driven by the intake cam 19a of the intake camshaft 19 The opening and closing timing is retarded.
[0047]
When the actual valve timing converges to the target valve timing, the feedback current value becomes 0, and the spool 36g of the oil flow control valve 36R (36L) closes the advance side oil passage 34 and the retard side oil passage 35. The vane rotor 28 of the variable valve timing mechanism 27 is stopped and held.
[0048]
After executing the above normal valve timing control, the process proceeds from step S101 to step S102, where the current control duty dVVT for the oil flow control valve 36R (36L) is determined by the determination values K1, K2 (K1 <K2). Check if it is within range. Determination values K1 and K2 are set based on the holding current value learned for each oil flow control valve 36R (36L) and the upper limit regulation value for regulating the feedback current value for each engine speed range. The control duty corresponding to the value obtained by subtracting the minimum value among the upper limit regulation values for each area from the holding current value is set as the determination value K1, and the minimum value among the upper limit regulation values for each area is added to the holding current value. A control duty corresponding to the determined value is set as a determination value K2.
[0049]
That is, as described above, the current value of the oil flow control valve 36R (36L) is learned for each individual, and feedback according to the difference between the target valve timing and the actual valve timing is learned for this holding current value. Since the current value is added or subtracted, if the control duty dVVT is within the range determined by the determination values K1 and K2, the mechanism of the valve timing mechanism 27 including the oil flow control valve 36R (36L) is slidable. It can be determined that there is no deterioration, foreign matter biting, and the like, and that this is a good operating state that does not require a cleaning operation. For simplicity, the determination values K1 and K2 may be fixed values obtained in advance by simulation or experiment in consideration of the specifications and characteristics of the mechanical system.
[0050]
When K1 ≦ dVVT ≦ K2, it is determined that the variable valve timing mechanism 27 is operating normally, and the routine exits from step S102. When dVVT <K1 or dVVT> K2, the routine proceeds from step S102 to step S103. It is checked whether the control duty dVVT is outside the set range and whether the set time has elapsed. This set time is a determination condition that is added to prevent an erroneous determination with respect to a temporary deviation from the set range of the control duty dVVT caused by an increase in sliding resistance in a short time, foreign object biting, or the like.
[0051]
As a result, in step S103, if the duration when the control duty dVVT is outside the set range is less than the set time, the routine is exited, and if the duration when the control duty dVVT is outside the set range has exceeded the set time, the hydraulic pressure It is determined that a foreign matter bite in the system, sliding failure of the sliding portion, increase or deterioration of the viscosity of the hydraulic oil, and some trouble has occurred in the valve timing mechanism 27, and the process proceeds to step S104, where the variable valve timing mechanism Operate 27 in the cleaning mode to exit the routine.
[0052]
In the cleaning mode, the amount of operation of the variable valve timing mechanism 27 is forcibly increased as compared with the control to the normal target valve timing to increase the circulating oil amount, and the variable valve timing mechanism 27 and the oil flow control valve 36R (36L) are increased. ) In which the sliding portion and the oil passage are cleaned, and the variable valve timing mechanism 27 is operated in the entire movable range or in a range close to the entire range.
[0053]
For example, when the vane rotor 28 of the variable valve timing mechanism 27 is reciprocated by a full stroke alternately between the most advanced angle position and the most retarded angle position in order to enhance the cleaning effect, the oil flow control valve 36R (36L) is used. The control duty to be output is set for each set time to a control duty for providing a minimum cleaning current value for operating the variable valve timing mechanism 27 to the most retarded position and a control duty for providing a maximum cleaning current value for operating to the most advanced position. By alternately switching, the variable valve timing mechanism 27 is operated in full stroke to the most advanced angle position and the most retarded angle position, and the sliding portion and the oil passage of the variable valve timing mechanism 27 and the oil flow control valve 36R (36L) are moved. Clean to recover from poor sliding due to foreign material bites and impurities.
[0054]
If the control duty dVVT is still outside the setting range of the determination values K1 and K2 even after the operation in the cleaning mode is performed for a certain period of time, this control is stopped and the control is shifted to the abnormal control if the problem cannot be resolved. .
[0055]
Thus, in the present embodiment, whether or not the control duty of the oil flow control valve has become too small or too large beyond the set range determined by the determination values K1 and K2 reflecting the learning value and the feedback control amount. Therefore, it is possible to accurately detect the actual operating state of the valve timing mechanism including the oil flow control valve and reliably detect defects such as foreign object biting. Can be improved.
[0056]
【The invention's effect】
As described above, according to the present invention, it is possible to optimize the execution judgment criteria for the cleaning operation of the variable valve timing mechanism and accurately grasp the actual operation state of the mechanism system, thereby improving the effectiveness of the cleaning operation. be able to.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of an engine with a variable valve timing mechanism.
FIG. 2 is a schematic configuration diagram of a variable valve timing mechanism.
3 is an explanatory view showing the most advanced angle state of the variable valve timing mechanism in the AA cross section of FIG.
4 is an explanatory view showing the most retarded state of the variable valve timing mechanism in the AA cross section of FIG. 2;
FIG. 5 is a circuit configuration diagram of an electronic control system.
FIG. 6 is a flowchart of a valve timing control routine.
[Explanation of symbols]
1 Engine with variable valve timing mechanism
5a Throttle valve
27 Variable valve timing mechanism
36R (36L) Oil flow control valve (hydraulic control valve)
60 Electronic control unit
dVVT control duty
K1, K2 judgment value

Claims (2)

A hydraulically driven variable valve timing mechanism that adjusts the rotational phase between the crankshaft and camshaft of the engine is controlled according to the engine operating state, and the operating amount of the variable valve timing mechanism is forcibly set when a predetermined condition is satisfied. In the valve timing control device for the engine that increases the hydraulic system cleaning operation,
Check whether the control amount for the hydraulic control valve that controls the hydraulic pressure of the variable valve timing mechanism is within the setting range based on the feedback control amount by proportional differential control, and set the time when the control amount is outside the setting range Means for determining that the execution condition of the cleaning operation is satisfied, when continuing for more than a time;
A valve timing control device for an engine, comprising: means for operating the variable valve timing mechanism at a most advanced angle position and a most retarded angle position when it is determined that the execution condition for the cleaning operation is satisfied. . The setting range is a value obtained by adding or subtracting the minimum value of the upper limit regulation value for the feedback control amount for each engine speed region from the control amount learning value for maintaining the variable valve timing mechanism in a steady state at a predetermined cam phase. The valve timing control device for an engine according to claim 1, wherein the valve timing control device is set corresponding to

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