JP4108789B2 - Engine valve timing control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine valve timing control device including a variable valve timing mechanism that changes the valve timing of at least one of an intake valve and an exhaust valve.
[0002]
[Prior art]
Conventionally, as this type of technology, one disclosed in Japanese Patent Application Laid-Open No. 8-74530 is known. In this technique, the control hydraulic 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 thus the valve timing. . By the way, 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. A control duty value is calculated based on the deviation and the holding duty value. Note that the holding duty value is a duty value when the VVT advance speed is “0”, in other words, a duty value for maintaining the current advance value.
[0003]
This holding duty value can vary depending on OCV manufacturing tolerance, aging, hydraulic oil temperature, engine speed, and the like. For this reason, in the above technique, this holding duty value is updated according to the operation state at that time, except immediately after starting or when the oil temperature is equal to or lower than a predetermined temperature (for example, α2 in FIG. 7). In the prior art, the hold duty value is learned and updated so as to be used at the next engine start-up. That is, in the above prior art, learning is performed 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 holding duty value learned last time. I am trying to calculate.
[0004]
[Problems to be solved by the invention]
However, the prior art has the following problems. That is, the inventors of the present application show that the actual holding duty value DA with respect to the oil temperature (or water temperature) is high on the low temperature side (for example, α1) and the high temperature side (for example, α4) as shown in FIG. For example, it has been found that α3) has a low relationship. Under such circumstances, the following problems may occur when learning control is performed as in the prior art.
[0005]
That is, at the time of the previous operation, it is assumed that the holding duty value DA is learned with the oil temperature α3 in the intermediate region, and then the engine is stopped. In the next operation, when the engine is started at the oil temperature α1 on the low temperature side, the appropriate holding duty value DA is β3 corresponding to the oil temperature α1, but the above prior art has learned last time. Β1 corresponding to the oil temperature α3 will be adopted as the holding duty value DA. Therefore, there is a possibility that a VVT control error (error on the retard side) corresponding to the deviation ΔDA1 between β3 and β1 may occur. As a result, there is a risk that torque shortage and consequently acceleration failure may occur due to insufficient advance amount of VVT.
[0006]
The present invention has been made in view of the above-described circumstances, and an object of the present invention is to calculate a control value based on a hold control value and control a variable valve timing mechanism based on the control value. It is an object to provide an engine valve timing control device that can obtain an appropriate holding control value at the time of starting or cold, and can prevent adverse effects on the engine such as poor acceleration. .
[0007]
[Means for Solving the Problems]
In order to achieve the above object, in the invention described in claim 1,
At least one of the intake valve and the exhaust valve is driven at a predetermined timing in synchronization with the crankshaft of the engine and opens and closes the intake passage and the exhaust passage respectively leading to the combustion chamber. The variable valve timing mechanism to be changed, the actuator for driving the variable valve timing mechanism, the operating state detecting means for detecting the operating state of the engine, and the variable valve timing based on the detection result of the operating state detecting means. Target valve timing calculation means for calculating a target value of valve timing changed by a mechanism, actual valve timing detection means for detecting actual valve timing changed by the variable valve timing mechanism, and target valve timing calculation means Calculation A deviation calculating means for calculating a deviation between the set target value and the actual valve timing detected by the actual valve timing detecting means, at least the deviation calculated by the deviation calculating means, and the variable valve timing mechanism Control value calculation means for calculating a control value based on a holding control value for maintaining a constant advance amount, and variable by controlling the actuator based on the control value calculated by the control value calculation means Control means for controlling the valve timing mechanism, and the holding control value during operation of the engine Holding control learning value that is the learning value of Holding control value learning means for learning update, and learned by the learning means when the engine is started or cold Said A variable valve timing control device for an engine that uses a hold control learning value as a hold control value, wherein the hold control value is high at a low temperature side and a high temperature side with respect to the temperature of the engine, and low in an intermediate region Yes, said holding control value learning means The holding control learning value by The gist of the invention is that a learning update permission means for allowing the learning update only when the temperature of the engine is on the high temperature side is provided.
[0008]
According to a second aspect of the present invention, in the variable valve timing control device for an engine according to the first aspect, When the engine temperature is high The main point is that the engine is satisfied when the engine is completely warmed up.
[0009]
Further, according to a third aspect of the present invention, in the variable valve timing control device for an engine according to the first or second aspect, the actuator is duty-controlled to adjust a control hydraulic pressure supplied to the variable valve timing mechanism. The gist of this is an oil control valve.
[0010]
(Function)
According to the first aspect of the present invention, the intake valve and the exhaust valve are each driven at a predetermined timing in synchronization with the crankshaft of the engine, and open and close the intake passage and the exhaust passage leading to the combustion chamber, respectively. The variable valve timing mechanism is driven by an actuator and changes the valve timing of at least one of the intake valve and the exhaust valve.
[0011]
The operating state of the engine is detected by the operating state detecting means, and based on the detection result, the target valve timing calculating means calculates the target value of the valve timing changed by the variable valve timing mechanism. Further, the actual valve timing detection means detects the actual valve timing changed by the variable valve timing mechanism. Further, the 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. Then, the control value calculation means calculates the control value based on at least the deviation calculated by the deviation calculation means and the hold 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.
[0012]
Further, during the operation of the engine, the holding control value is learned by the holding control value learning means. Hold control learning value that is the learning value of Is updated. For this reason, the holding control value may fluctuate due to manufacturing tolerances of the actuator or the like, a change with time, and the like, but the holding control value is optimized by performing such learning update.
[0013]
Further, when the engine is started or 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 above invention, the actual holding with respect to the engine temperature (for example, oil temperature or water temperature). control The value is high on the low temperature side and high temperature side, and low in the intermediate region. On the other hand, in the present invention, the holding control value learning means The holding control learning value by The learning update is permitted only when the engine temperature is high by the learning update permission means. For this reason, the holding control learning value that is allowed to be updated only on the high temperature side does not differ much from the actual holding control value on the low temperature side, and is therefore used at the next start-up or cold time. The holding control value that can be obtained can be almost appropriate.
[0014]
According to the invention described in claim 2, in addition to the action of the invention described in claim 1, When the engine temperature is high Is satisfied when the engine is completely warmed up. For this reason, the said effect | action is more reliably show | played.
[0015]
Furthermore, according to the invention described in claim 3, in addition to the operation of the invention described in claims 1 and 2, the actuator is duty-controlled to adjust the control hydraulic pressure supplied to the variable valve timing mechanism. This is an oil control valve. That is, the holding duty value of the oil control valve used at the next start or cold can be almost appropriate.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which a valve timing control device for an engine of the present invention is embodied in a gasoline engine will be described with reference to the drawings.
[0017]
First, the configuration of the valve timing control device VC of the engine 10 will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic configuration diagram showing a gasoline engine system including an engine valve timing control device VC.
[0018]
The engine 10 includes a cylinder block 11 in which a plurality of cylinders are formed, a cylinder head 12 connected to the upper portion of the cylinder block 11, 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 portion of the piston 13, and the crankshaft 14 is rotated when the piston 13 moves up and down.
[0019]
Further, a crank angle sensor 40 is disposed in the vicinity of the crankshaft 14, and the crank angle sensor 40 includes a magnetic rotor (not shown) connected to the crankshaft 14 and an electromagnetic pickup (not shown). It consists of and. Here, equiangular teeth having missing teeth are formed on the outer periphery of the rotor, and a pulsed crank angle signal is detected each time the equiangular teeth of the rotor pass in front of the electromagnetic pickup. Then, after a reference position signal is generated by a cylinder discrimination sensor 42 described later, the rotation angle (crank angle) of the crankshaft 14 is detected by measuring the number of crank angle signals generated from the crank angle sensor 40.
[0020]
A space defined by each cylinder block 11 and the inner wall of the cylinder head 12 and the top of the piston 13 functions as a combustion chamber 15 for burning the air-fuel mixture. A spark plug 16 for igniting the air-fuel mixture is disposed on the top of the cylinder head 12 so as to protrude into the combustion chamber 15. Each spark plug 16 is connected to a distributor 18 via a plug cord or the like (not shown). The high voltage output from the igniter 19 is distributed to each spark plug 16 by the distributor 18 in synchronization with the crank angle.
[0021]
Further, the distributor 18 is provided with an engine speed sensor 41 that is connected to the exhaust side camshaft 33 and detects the speed of the crankshaft 14. 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), and the crankshaft is detected when the electromagnetic pickup detects the speed of the rotor. 14 (engine speed NE) is detected. Further, the distributor 18 is provided with a cylinder discrimination sensor 42 for detecting a reference position of the crank at a predetermined ratio from the rotation of the rotor.
[0022]
The cylinder block 11 is provided with a water temperature sensor 43 for detecting the temperature (cooling water temperature) THW of the cooling water flowing through the cooling water passage. The cylinder head 12 has an intake port 22 and an exhaust port 32, the intake passage 20 is connected to the intake port 22, and the exhaust passage 30 is connected to the exhaust port 32. An intake valve 21 is disposed in the intake port 22 of the cylinder head 12, and an exhaust valve 31 is disposed in the exhaust port 32.
[0023]
An intake side camshaft 23 for opening and closing the intake valve 21 is disposed above the intake valve 21, and an exhaust side camshaft 33 for opening and closing the exhaust valve 31 is disposed above the exhaust valve 31. Is arranged. An intake side timing pulley 27 and an exhaust side timing pulley 34 are attached to one end of each camshaft 23, 33, and each timing pulley 27, 34 is connected to the crankshaft 14 via a timing belt 35. Has been.
[0024]
Therefore, when the engine 10 is operated, the rotational driving force is transmitted from the crankshaft 14 to the camshafts 23 and 33 via the timing belt 35 and the timing pulleys 27 and 34, and the camshafts 23 and 33 rotate so that the intake air is generated. The valve 21 and the exhaust valve 31 are driven to open and close. These valves 21 and 31 are synchronized with the rotation of the crankshaft 14 and the vertical movement of the piston 13, that is, synchronized with a series of four strokes in the engine 10 including an intake stroke, a compression stroke, an explosion / expansion stroke, and an exhaust stroke. Then, it is driven at a predetermined opening / closing timing.
[0025]
Further, a cam angle sensor 44 for detecting the valve timing of the intake valve 21 is disposed in the vicinity of the intake side cam shaft 23, and the cam angle sensor 44 is a magnetic connected to the intake side cam shaft 23. It consists of a body rotor (not shown) and an electromagnetic pickup. Further, a plurality of teeth are formed at equal angles on the outer periphery of the magnetic rotor. For example, before the compression top dead center (TDC) of a predetermined cylinder, the intake side cam is between BTDC 90 ° and 30 °. A pulsed cam angle signal accompanying the rotation of the shaft 23 is detected.
[0026]
An air cleaner 24 is connected to the air intake side of the intake passage 20, and a throttle valve 26 that is opened and closed in conjunction with an accelerator pedal (not shown) is disposed in the intake passage 20. The intake air amount is adjusted by opening and closing the accelerator pedal.
[0027]
In the vicinity of the throttle valve 26, a throttle sensor 45 for detecting the throttle opening degree TA and a fully closed switch 46 for detecting the fully closed state of the throttle valve 26 are provided.
[0028]
Further, a surge tank 25 for suppressing intake pulsation is formed on the downstream side of the throttle valve 26. The surge tank 25 is provided with an intake pressure sensor 47 that detects intake pressure (PiM) in the surge tank 25. In addition, an injector 17 for supplying fuel to the combustion chamber 15 is disposed near the intake port 22 of each cylinder. Each injector 17 is an electromagnetic valve that is opened by energization, and fuel that is pumped from a fuel pump (not shown) is supplied to each injector 17.
[0029]
Therefore, when the engine 10 is in operation, 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 simultaneously with the intake of the air. 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 as the intake valve 21 is opened in the intake stroke.
[0030]
A catalytic converter 36 having a built-in three-way catalyst for purifying exhaust gas is disposed in the middle of the exhaust passage 30. Further, an oxygen sensor 48 that detects the oxygen concentration in the exhaust gas is disposed in the middle of the exhaust passage 30.
[0031]
Further, the engine 10 is provided with a starter 28 for starting the engine 10. The starter 28 is provided with a starter switch 49 that detects its operating state. The starter switch 49 is a starter signal when an ignition switch (not shown) is operated from the OFF position to the start position by the driver when the engine 10 is started, and the starter is operating (in the cranking state). The STA is output as “ON”. In addition, when the start of the engine 10 is completed (a complete explosion state) and the ignition switch is returned from the start position to the ON position, the starter switch 49 outputs the starter signal STA as “off”.
[0032]
In the present embodiment, the crank angle sensor 40, the engine speed sensor 41, the cylinder discrimination sensor 42, the water temperature sensor 43, the cam angle sensor 44, the throttle sensor 45, the fully closed switch 46, the intake pressure sensor 47, and the oxygen sensor 48 described above. The operation state detecting means is constituted by the starter switch 49 and the like. In particular, the actual valve timing detection means is configured by the cam angle sensor 44, the crank angle sensor 40, and the like.
[0033]
In the gasoline engine system of the present embodiment, a variable valve timing mechanism 50 (hereinafter referred to as “VVT”) driven by hydraulic pressure in order to change the opening / closing timing of the intake valve 21 (change of the valve overlap amount). Is arranged. The VVT 50 is a mechanism for continuously changing the valve timing of the intake valve 21 by changing the rotation phase of the intake side camshaft 23 with respect to the rotation of the crankshaft 14 (intake side timing pulley 27).
[0034]
The system configuration of the VVT 50 will be described with reference to FIG. FIG. 2 is an explanatory diagram showing a cross section in the vicinity of the intake camshaft 23 where the VVT 50 is disposed, and the entire control system of the VVT 50.
[0035]
The control system of the VVT 50 includes an oil control valve 80 (hereinafter referred to as “OCV”) that constitutes an actuator that applies a driving force to the VVT 50, a cam angle sensor 44 that detects a cam angle signal, various other sensors, And an electronic control unit (hereinafter referred to as “ECU”) 70 that drives and controls the OCV 80 based on input signals from various sensors including the cam angle sensor 44.
[0036]
The VVT 50 is disposed between the intake side camshaft 23 and the intake side timing pulley 27, and the intake side camshaft 23 is rotatably supported between the cylinder head 12 and the bearing cap 51. An intake side timing pulley 27 is mounted in the vicinity of the front end portion of the intake side camshaft 23 so as to be relatively rotatable, and an inner cap 52 is attached to the front end of the intake side camshaft 23 by a hollow bolt 53 and a pin 54. It is attached so that it can rotate integrally.
[0037]
A housing 56 having a cap 55 is attached to the intake side timing pulley 27 so as to be integrally rotatable by a bolt 57 and a pin 58, and this housing 56 allows the front end of the intake side camshaft 23 and the entire inner cap 52 to be rotated. Is covered. In addition, a large number of external teeth 27 a for hooking the timing belt 35 are formed on the outer periphery of the intake side timing pulley 27.
[0038]
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 capable of reciprocating in the axial direction of the intake side camshaft 23. A large number of teeth 59 a and 59 b are formed on the inner and outer periphery of the ring gear 59.
[0039]
Correspondingly, a large number of teeth 52a and 56b are formed on the outer periphery of the inner cap 52 and the inner periphery of the housing 56, respectively. All of these teeth 59a, 59b, 52a, 56b are helical teeth whose tooth lines intersect with the axis of the intake camshaft 23 at a predetermined angle. That is, a helical spline is formed in which the teeth 52a and the teeth 59a mesh with each other, and the teeth 56b and the teeth 59b mesh with each other. The rotation of the intake side timing pulley 27 is transmitted to the intake side camshaft 23 through the housing 56 and the inner cap 52 by these meshing. Since each tooth 59a, 59b, 52a, 56b is a helical tooth, 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.
[0040]
In the space S, in order to move the ring gear 59 in the axial direction, a first hydraulic chamber 60 is formed on the front end side of the ring gear 59 and a second hydraulic chamber 61 is formed on the rear end side of the ring gear 59. The bearing cap 51 is formed with a first hydraulic pressure supply hole 51a and a second hydraulic pressure supply hole 51b. Further, in the intake side camshaft 23, the first hydraulic pressure supply passage 62 that communicates the first hydraulic pressure supply hole 51a and the first hydraulic chamber 60, and the second hydraulic pressure supply hole 51b and the second hydraulic chamber 61 communicate. A second hydraulic pressure supply passage 63 is formed.
[0041]
Then, the lubricating oil sucked up from the oil pan 65 by the hydraulic pump 64 is supplied to the hydraulic supply holes 51a and 51b through the oil filter 66 with a predetermined pressure. Further, an OCV 80 is connected to each of the hydraulic pressure supply holes 51a and 51b in order to selectively supply the hydraulic pressure to the respective hydraulic chambers 60 and 61 via the respective hydraulic pressure supply paths 62 and 63.
[0042]
The OCV 80 is a 4-port directional control valve that switches the flow direction of the lubricating oil when the plunger 83 driven by the electromagnetic actuator 81 and the coil spring 82 reciprocates the spool 84 in the axial direction. The opening degree of the electromagnetic actuator 81 is adjusted by duty control of the electromagnetic actuator 81, and the hydraulic pressure supplied to the hydraulic chambers 60 and 61 is adjusted.
[0043]
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 the hydraulic pump 64, the A port 85a is connected to the first hydraulic pressure supply hole 51a, and the B port 85b is connected to the second hydraulic pressure supply hole 51b. . The reservoir port 85r is in communication with the oil pan 65.
[0044]
The spool 84 is a cylindrical valve body, and four lands 84a that seal the flow of the lubricating oil between the two ports, and a passage 84b that communicates between the two ports and allows the flow of the lubricating oil, Furthermore, it has two other passages 84c.
[0045]
In the VVT 50 having these configurations, when the OCV 80 is driven and controlled and the spool 84 is moved to the left in the drawing, the central passage 84b communicates the tank port 85t and the A port 85a, and the first hydraulic pressure supply hole Lubricating oil is supplied to 51a. The lubricating oil supplied to the first hydraulic pressure supply hole 51 a is supplied to the first hydraulic chamber 60 via the first hydraulic pressure supply path 62, and the hydraulic pressure is applied to the tip side of the ring gear 59.
[0046]
At the same time, the passage 84c on the right side in the drawing communicates the B port 85b and the reservoir port 85r, and the lubricating oil in the second hydraulic chamber 61 flows through the second hydraulic supply path 63, the second hydraulic supply hole 51b, The oil is discharged to the oil pan 65 through the B port 85b and the reservoir port 85r of the OCV 80.
[0047]
Accordingly, the ring gear 59 is moved while being rotated to the rear end side (right side in the drawing) by the hydraulic pressure applied to the front end side, and the intake side camshaft 23 is twisted 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, the intake side camshaft 23 rotates from the most retarded position to the most advanced position, and the intake valve 21 Is advanced (the valve overlap amount is large).
[0048]
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 overlap amount at which the intake valve 21 and the exhaust valve 31 are simultaneously opened is large. Enlarged. The movement of the ring gear 59 toward the rear end side is restricted by the ring gear 59 coming into contact with the intake side timing pulley 27, and when the ring gear 59 stops coming into contact with the intake side timing pulley 27, the intake valve 21 is moved. The valve opening timing is the earliest.
[0049]
On the other hand, when the OCV 80 is driven and controlled, and the spool 84 is moved to the right in the drawing, the central passage 84b communicates the tank port 85t and the B port 85b and supplies lubricating oil to the second hydraulic pressure supply hole 51b. Is done. The lubricating oil supplied to the second hydraulic pressure supply hole 51 b is supplied to the second hydraulic chamber 61 via the second hydraulic pressure supply path 63, and the hydraulic pressure is applied to the rear end side of the ring gear 59.
[0050]
At the same time, the passage 84c on the left side in the drawing communicates the A port 85a and the reservoir port 85r, and the lubricating oil in the first hydraulic chamber 60 flows through the first hydraulic supply passage 62, the first hydraulic supply hole 51a, The oil is discharged to the oil pan 65 through the A port 85a and the reservoir port 85r of the OCV 80.
[0051]
Accordingly, the ring gear 59 is moved while being rotated to the front end side (left side in the drawing) by the hydraulic pressure applied to the rear end side, and a reverse twist is applied 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, the intake side camshaft 23 rotates from the most advanced position to the most retarded position, and the intake valve 21 Is delayed (the valve overlap amount is small).
[0052]
Thus, by delaying the opening timing of the intake valve 21, the valve overlap amount at which the intake valve 21 and the exhaust valve 31 are opened simultaneously is shortened or made zero. The movement of the ring gear 59 toward the tip side is restricted by the ring gear 59 coming into contact with the housing 56, and when the ring gear 59 comes into contact with the housing 56 and stops, the opening timing of the intake valve 21 becomes the latest. .
[0053]
The actual valve timing of the intake valve 21 changed by the VVT 50 is calculated from the cam angle signal output from the cam angle sensor 44 and the crank angle signal output from the crank angle sensor 40. That is, a time required for inputting the crank angle signal (reference NE timing signal) of BTDC 30 ° after the cam angle signal is input to the ECU 70, for example, the engine speed NE is measured, and the time is used as the displacement angle. By converting, the actual displacement angle of the intake camshaft 23 with respect to the crankshaft 14 is calculated.
[0054]
Next, the 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 the 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 calculation means, deviation calculation means, control value calculation means, control means, holding control value learning means, learning update permission means, and the like.
[0055]
The ECU 70 has a ROM 71 that stores various control programs such as a VVT control program and a map for changing the valve timing corresponding to various conditions. Further, the ECU 70 executes a calculation process based on a control program stored in the ROM 71, a RAM 73 that temporarily stores calculation results in the CPU 72, data input from each sensor, and the like, and stores in the RAM 73 when power supply is stopped. A backup RAM 74 for holding the various data. The CPU 72, ROM 71, RAM 73, and backup RAM 74 are connected to each other via a bidirectional bus 75 and are connected to an input interface 76 and an output interface 77.
[0056]
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, an intake pressure sensor 47, an oxygen sensor 48, a starter. A switch 49 or the like is connected. If the signal output from each sensor or the like is an analog signal, it is converted to a digital signal by an A / D converter (not shown) and then output to the bidirectional bus 75. The output interface 77 is connected to external circuits such as the injector 17, the igniter 19, and the OCV 62, and these external circuits are controlled based on the calculation result of the control program executed by the CPU 72.
[0057]
Next, a variable valve timing (VVT) control program in the engine valve timing control device VC according to the present embodiment having the above-described configuration will be described with reference to the flowcharts shown in FIGS. That is, the flowcharts shown in FIGS. 4 to 6 show a “holding duty value learning control routine” executed by the ECU 70 in order to calculate the control duty value Uk and to learn the holding duty value DA. It is executed by interruption every predetermined crank angle.
[0058]
When the processing shifts to this routine, the ECU 70 first reads signals indicating various operation states based on detection signals from various sensors in step 101 (see FIG. 4).
[0059]
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 cam shaft advance value (hereinafter referred to as "actual advance angle"). Read VTB (referred to as "value"). In step 103, a target camshaft advance value (hereinafter referred to as "target advance value") VTT is calculated based on the current operating state.
[0060]
Further, in the subsequent 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.
In step 105, the ECU 70 compares the currently calculated deviation Ek with “0”. When the deviation Ek is “0” or more, the process proceeds to step 106.
[0061]
In step 106, the ECU 70 calculates a control duty value Uk according to the following equation (1) in order to set the valve timing to the advance side.
Uk = Kp1 * Ek + Kd1 (Ek−Ek _i-1 ) + DA ...... (1)
Here, Kp1 and Kd1 are feedback gains. Ek _i-1 Is the previous deviation Ek.
[0062]
On the other hand, when the deviation Ek is negative in step 105, the routine proceeds to step 107.
In step 107, the ECU 70 calculates a control duty value Uk according to the following equation (2) in order to set the valve timing to the retard side.
[0063]
Uk = Kp2 * Ek + Kd2 (Ek−Ek _i-1 ) + DA ...... (2)
Here, Kp2 and Kd2 are feedback gains. In the present embodiment, the feedback gain is set to a different value between the above formulas (1) and (2), but the same value may be used. Then, the calculated control duty value Uk is output to the OCV 80 (linear solenoid) as a control signal.
[0064]
Now, shifting from step 106 or step 107, in step 108, the ECU 70 determines whether or not the starter signal STA is on. If the starter signal STA is on, it is determined that the current time is the start time, and the routine proceeds to step 109. In step 109, the learned hold duty learning value DAM stored in the RAM 73 is set as the hold duty value DA, and the hold duty learned value DAM is used as the hold duty value DA (i) used for the current calculation. Set as. Then, the ECU 70 once ends the subsequent processing.
[0065]
If the starter signal STA is off in step 108, it is determined that the current time is not the start time, and the routine proceeds to step 110. In step 110, it is determined whether or not the current coolant temperature THW is equal to or higher than a predetermined value α2 (see FIG. 7). Here, the predetermined value α2 is a value serving as a boundary for determining whether or not the time is cold. If the current coolant temperature THW is less than the predetermined value α2, the ECU 70 determines that the current time is cold and proceeds to step 109 as described above. In other words, the holding duty learning value DAM that is learned and stored in the 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) that is used for the current calculation. . Then, the ECU 70 once ends the subsequent processing.
[0066]
On the other hand, when the current coolant temperature THW is equal to or higher than the predetermined value α2, the ECU 70 determines that the present is neither the start time nor the cold time, and proceeds to step 111 (see FIG. 5). In step 111, the ECU 70 determines whether or not a reference setting flag XKIJUN, which will be described later, is “1”. If the reference setting flag XKIJUN is not “1”, that is, “0”, step 112 (FIG. 6) is set in order to set a reference value (actual reference value YA, target reference value RA) for determining learning condition establishment. Go to Reference).
[0067]
In step 112, the ECU 70 inputs the current target advance value VTT as the target reference value RA and also inputs the current actual advance value VTB as the actual reference value YA. At the same time, the reference setting flag XKIJUN is set to “1”.
[0068]
Further, in the next step 113, the count value C1 of the counter is cleared to “0”, and in the subsequent step 114, the learning flag XGKS for determining the learning condition is set to “0”. Further, in step 115, the ECU 70 erases the stored value UkM of the control duty value Uk currently stored in the RAM 73. Then, the subsequent processing is temporarily terminated.
[0069]
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, is “0”, the process proceeds to step 117.
[0070]
In step 117, the ECU 70 determines whether or not the target advance value VTT is substantially constant. That is, it is determined whether or not the fluctuation range of the target advance value VTT with respect to the target reference value RA is within the minute range ΔR. If the target advance value VTT is not substantially constant, the process proceeds to step 112 described above, and the input of the target reference value RA, the actual reference value YA, etc. is performed again (steps 112 to 115).
[0071]
On the other hand, when 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 fluctuation range of the actual advance value VTB with respect to the actual reference value YA is within the minute range ΔY. Even when the actual advance value VTB is not substantially constant, the process proceeds to step 112 described above, and the input of the target reference value RA, the actual reference value YA, etc. is performed again (steps 112 to 115). On the other hand, when the actual advance value VTB is substantially constant, the routine proceeds to step 119 in order to execute the learning control of the holding duty DA.
[0072]
In step 119, it is determined whether or not the count value C1 of the counter described above is equal to or greater than a predetermined time T1. If the count value C1 is not yet 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 routine proceeds to step 120.
[0073]
In step 120, the ECU 70 sets the learning flag XGKS to “1”, and in the subsequent step 121, sets the current control duty value Uk as the stored value UkM. Further, in the next step 122, the count value C2 of the counter is cleared to “0”, and the subsequent processing is once ended.
[0074]
If the learning flag XGKS is “1” in step 116, the process proceeds to step 123. In step 123, it is determined again whether or not the actual reference value YA is substantially constant. That is, it is determined whether or not the fluctuation range of the actual advance value VTB with respect to the actual reference value YA is within the minute range ΔY. If the actual advance value VTB is not substantially constant, the process proceeds to step 112 described above, and the input of the target reference value RA, the actual reference value YA, etc. is performed again (steps 112 to 115). If the actual advance value VTB is substantially constant, it is confirmed that the actual advance value VTB is not substantially changed even if the stored control duty value Uk (stored value UkM) is used. To do.
In step 124, it is determined whether or not the count value C2 of the counter is equal to or longer than a predetermined time T2. If the count value C2 is not yet equal to or longer than the predetermined time T2, the subsequent processing is temporarily terminated. On the other hand, if the count value C2 is equal to or longer than the predetermined time T2, it can be confirmed that the actual advance value VTB is substantially unchanged during the predetermined time (T2) even if the stored value UkM is used. 125.
[0075]
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 fact that the coolant temperature THW is equal to or higher than the predetermined value α4 means that the engine 10 is in a completely warm-up state, and the holding duty value DA is equal to or higher than a corresponding level as shown in FIG. Means. If the current coolant 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-up or cold time, and thereafter The process is temporarily terminated. On the other hand, when the current coolant temperature THW is equal to or higher than the predetermined value α4, the ECU 70 determines in step 127 that the holding duty value DA is stored for the next start-up or cold time. The holding duty value DA is set as the holding duty learning value DAM. 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 is temporarily terminated.
[0076]
Thus, in the “holding duty value learning control routine”, the control duty value Uk is calculated based on the deviation Ek between the target advance angle value VTT and the actual advance angle value VTB and the hold duty value DA. Is done. At the same time, the holding duty value DA is learned and updated for the next start-up or cold time under predetermined conditions.
[0077]
Next, the operation and effect of the present embodiment will be described.
In the present embodiment, the holding duty value DA is updated as appropriate during the operation of the engine 10. For this reason, the holding duty value DA is inherently variable due to the manufacturing tolerance of the OCV 80, a change with time, and the like, but the holding duty value DA is optimized by such learning update.
[0078]
Further, when the engine 10 is started or cold, the hold duty learned value DAM learned in advance is set as the hold duty value DA. Incidentally, as shown in FIG. 7, the actual holding duty value DA with respect to the temperature of the engine 10 (for example, the oil temperature or the cooling water temperature THW) is high on the low temperature side and high temperature side, and low in the intermediate region. In contrast, in the present embodiment, learning update of holding duty learning value DAM is allowed only when the temperature of engine 10 is equal to or higher than a predetermined temperature, that is, only when cooling water temperature THW is equal to or higher than predetermined value α4.
[0079]
For this reason, the holding duty learning value DAM that is greater than or equal to the predetermined value α4, that is, the learning update permitted only on the high temperature side, is between the actual holding duty value DA on the low temperature side at the next start (or cold). There is not much difference. For example, if learning is performed at a time when the coolant temperature THW corresponds to the predetermined value α4 in the figure, the holding duty value DA (holding duty learning value DAM) is “β2”, whereas in the cold time, etc. The actual holding duty value DA at the time when the cooling water temperature THW corresponds to the predetermined value α1 is “β3”, and the difference between them is as small as ΔDA2. Therefore, the holding duty value DA used at the next start or cold time can be almost appropriate.
[0080]
Therefore, it is possible to prevent a valve timing control error (error on the retard side) from occurring. As a result, it is possible to surely prevent an adverse effect on the engine 10 that a torque shortage and an acceleration failure occur due to a short valve timing advance amount.
[0081]
In particular, the predetermined value α4 satisfies one condition when the engine 10 is in a completely warmed-up state. For this reason, the said effect is more reliably show | played.
[0082]
Furthermore, in the present embodiment, learning control is performed only when the target advance value VTT and the actual advance value VTB are both substantially constant. For this reason, it is possible to improve learning accuracy by breaking erroneous learning.
[0083]
In addition, this invention is not limited to the said embodiment, A part of structure can be changed suitably in the range which does not deviate from the meaning of invention, and it can also implement as follows.
(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 or the like. This takes into account that the characteristic of the holding duty value DA as shown in FIG. 7 can also vary depending on the engine speed NE. Therefore, the controllability can be further improved by making the predetermined values α2 and α4 variable as described above.
[0084]
(2) In the above embodiment, the cooling water temperature THW is adopted as a parameter for determining whether or not learning update of the holding duty value DA is permitted. However, if the parameter corresponds to the temperature of the engine 10, other parameters are used. (For example, oil temperature etc.) may be adopted.
[0085]
(3) In the above-described embodiment, the VVT 50 in which the ring gear 59 moves is employed as the variable valve timing mechanism, but other types of VVT (for example, vane type VVT) may be employed.
[0086]
(4) In the above embodiment, the valve timing control of a gasoline engine as an engine is embodied, but it can also be embodied to that of a diesel engine.
[0087]
【The invention's effect】
As described above in detail, according to the present invention, in the valve timing control of the engine that calculates the control value based on the holding control value and controls the variable valve timing mechanism based on the control value, It is possible to obtain an appropriate holding control value at the time, and therefore, it is possible to prevent an adverse effect on the engine such as an acceleration failure.
[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 the configuration of VVT, OCV, and the like.
FIG. 3 is a block diagram showing an electrical configuration of the ECU.
FIG. 4 is a flowchart showing a “holding duty value learning control routine” executed by the ECU.
FIG. 5 is a flowchart continued from FIG. 4 and showing a “holding duty value learning control routine”;
FIG. 6 is a continuation of FIG. 5 and shows a “holding duty value learning control routine”;
FIG. 7 is a graph showing a characteristic of a holding duty value with respect to a cooling water temperature (or oil temperature).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 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 ... full-closed switch, 47 ... intake pressure sensor, 48 ... oxygen sensor, 49 ... starter switch (each sensor of 41-49 constitutes an operating state detecting means. , 44, 40, etc. constitute actual valve timing detection means.), 50 ... VVT, 70 ... Target valve timing calculation means, deviation calculation means, control value calculation means, control means, hold control value learning ECU which comprises a means, a learning update permission means, etc.

Claims (3)

An intake valve and an exhaust valve that are driven at predetermined timings in synchronization with the crankshaft of the engine and open and close the intake passage and the exhaust passage respectively leading to the combustion chamber;
A variable valve timing mechanism for changing the valve timing of at least one of the intake valve and the exhaust valve;
An actuator for driving the variable valve timing mechanism;
An operating state detecting means for detecting an operating state of the engine;
Target valve timing calculation means for calculating a target value of valve timing changed by the variable valve timing mechanism based on the detection result of the operating state detection means;
An actual valve timing detecting means for detecting an actual valve timing changed by the variable valve timing mechanism;
Deviation calculating means for calculating 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;
Control value calculation means for calculating 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;
Control means for controlling the variable valve timing mechanism by controlling the actuator based on the control value calculated by the control value calculating means;
Holding control value learning means for learning and updating a holding control learning value that is a learning value of the holding control value during operation of the engine, and learned by the learning means when the engine is started or cold. a variable valve timing control apparatus for an engine according to the holding control value with a said holding control learning value,
The holding control value is higher in the low temperature side and the higher temperature side than the engine temperature and low in the intermediate region, and learning update of the holding control learning value by the holding control value learning unit is performed by the engine A variable valve timing control device for an engine, characterized by comprising learning update permission means that permits only when the temperature of the engine is higher. The variable valve timing control device for an engine according to claim 1,
The variable valve timing control device for an engine, characterized in that when the temperature of the engine is on a high temperature side, the engine is satisfied when the engine is completely warmed up. The variable valve timing control device for an engine according to claim 1 or 2,
The variable valve timing control apparatus for an engine, wherein the actuator is an oil control valve that is duty-controlled to adjust a control hydraulic pressure supplied to the variable valve timing mechanism.

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