JP4532004B2 - Fuel injection control device for variable valve timing mechanism and supercharged engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a variable valve timing mechanism that optimizes fuel injection timing according to a valve overlap amount and a supercharging pressure, and a fuel injection control device for a supercharged engine.
[0002]
[Prior art]
In an engine having a variable valve timing mechanism that varies the opening / closing timing of at least one of the intake valve and the exhaust valve, the valve timing of at least one of the intake valve and the exhaust valve is changed according to the engine operating state. For example, during idling, the opening and closing timing of the intake valve is retarded to reduce the overlap amount between the exhaust valve and the intake valve to stabilize idle rotation. During high load operation, the opening and closing timing of the intake valve Advancing the angle to increase the overlap amount between the exhaust valve and the intake valve to improve the scavenging efficiency and improve the engine output, and to obtain the optimal valve timing for improving fuel efficiency during low and medium load operation I have to.
[0003]
However, when the valve overlap amount is increased by the valve timing control via the variable valve timing mechanism, there is a problem that the air-fuel mixture blows out from the intake side to the exhaust side. For this reason, at the conventional fuel injection timing in which the fuel injection is terminated immediately before the intake stroke, the rich air-fuel mixture or fuel remaining in the vicinity of the intake valve of the intake port is blown out to the exhaust side at the initial stage of the valve overlap, increasing the HC, It causes an increase in exhaust gas temperature due to combustion of unburned gas in the exhaust pipe, deterioration of fuel consumption, and the like.
[0004]
For this reason, in an engine equipped with a variable valve timing mechanism, a technique for controlling the fuel injection timing in response to a change in valve timing is employed. For example, in Japanese Patent Laid-Open No. 6-241102, when the load on the internal combustion engine is in a steady state, the first timing before the intake valve is opened is the fuel injection timing, and the load on the internal combustion engine is in a transient state. The fuel injection timing is the second timing after the first timing, and the longer the valve overlap time in which both the intake valve and the exhaust valve are open, the longer the second timing is delayed from the first timing. Technology is disclosed. In this prior art, when the load of the internal combustion engine fluctuates and the intake air amount is in a transitional state, the injected fuel is injected into the intake pipe inner wall by a backflow in which exhaust gas flows back into the intake pipe at the time of valve overlap. This prevents the difference between the required amount of fuel adhering to the fuel and the amount of fuel actually flowing into the combustion chamber, and improves the responsiveness of the internal combustion engine.
[0005]
[Problems to be solved by the invention]
However, in an engine equipped with a supercharger in addition to a variable valve timing mechanism, the pressure in the intake pipe is often higher than the exhaust gas pressure due to supercharging even in a steady state, and the fuel injection timing is only in the transient state as in the prior art. With the technology that delays the air flow, it is not possible to prevent the air-fuel mixture from blowing through from the intake side to the exhaust side, and deposit accumulation at the injection port of the injector due to exhaust blow-back and the heat of the resin cover around the injector and the injection port Damage may occur, and it is difficult to continue proper fuel injection.
[0006]
The present invention has been made in view of the above circumstances, and appropriately retards the fuel injection timing in accordance with the valve overlap amount and the supercharging pressure to prevent the air-fuel mixture from blowing through from the intake side to the exhaust side. An object of the present invention is to provide a variable valve timing mechanism and a fuel injection control device for a supercharged engine.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a first aspect of the present invention provides a variable valve timing mechanism and a supercharger comprising a variable valve timing mechanism and a supercharger for varying the opening / closing timing of at least one of an intake valve and an exhaust valve. A fuel injection control device for an attached engine, a fuel injection timing setting means for setting a fuel injection timing based on an engine load and an engine speed, and valves of an intake valve and an exhaust valve that are variable by the variable valve timing mechanism The retard amount of fuel injection timing is set based on the overlap amount and the boost pressure by the turbocharger. And a first correction coefficient that decreases as the opening degree of the control valve for controlling the supercharging pressure by the supercharger increases or a second correction coefficient that decreases as the opening degree of the throttle valve decreases. Correct the above retardation amount The fuel injection timing retarding means retards the fuel injection timing set by the fuel injection timing setting means as the valve overlap amount is large and the boost pressure is high.
[0008]
The invention according to claim 2 is the invention according to claim 1, The fuel injection timing retarding means sets a third correction coefficient based on the engine speed, and corrects the retard amount by the third correction coefficient. It is characterized by
[0012]
That is, according to the first aspect of the present invention, the valve overlap amounts of the intake valve and the exhaust valve that are variable by the variable valve timing mechanism with respect to the fuel injection timing set based on the engine load and the engine speed, and the supercharger The retard amount of fuel injection timing is set based on the supercharging pressure by In addition, the delay is caused by the first correction coefficient that decreases as the opening degree of the control valve for controlling the supercharging pressure by the supercharger increases or the second correction coefficient that decreases as the opening degree of the throttle valve decreases. Compensate angular amount However, the larger the valve overlap amount and the higher the supercharging pressure, the more retarded the fuel injection timing prevents the air-fuel mixture from blowing from the intake side to the exhaust side during supercharging.
[0013]
In that case, the invention of claim 2 of like , D It is desirable to set the retardation amount of the fuel injection timing more precisely according to the operating state by correcting the retardation amount of the fuel injection timing by the third correction coefficient based on the engine speed.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. 1 to 16 relate to a first embodiment of the present invention, FIG. 1 is an overall configuration diagram of a variable valve timing mechanism and a supercharged engine, FIG. 2 is a schematic configuration diagram of a variable valve timing mechanism, and FIG. FIG. 4 is an explanatory view showing the most advanced angle state of the variable valve timing mechanism in section AA in FIG. 2, FIG. 4 is an explanatory view showing the most retarded state of the variable valve timing mechanism in section AA in FIG. FIG. 6 is a front view of the crank rotor and the crank angle sensor, FIG. 7 is a rear view of the intake cam pulley, and FIG. 8 is a front view of the cam rotor and cam position sensor. 9 is a time chart showing the relationship among the crank pulse, cylinder discrimination pulse, and cam position pulse, FIG. 10 is a circuit configuration diagram of an electronic control system, FIG. 11 is a flowchart of a valve timing control routine, and FIG. 2 is an explanatory diagram showing a valve timing control region, FIG. 13 is a flowchart of a fuel injection amount / injection timing setting routine, FIG. 14 is an explanatory diagram of a basic fuel injection start timing, and FIG. 15 is an explanatory diagram of an injection timing retard amount, FIG. 16 is a flowchart of the INJST interrupt routine.
[0015]
First, the overall configuration of a variable valve timing mechanism and a supercharged engine to which the present invention is applied will be described with reference to FIG. In the figure, reference numeral 1 denotes a variable valve timing mechanism and an engine with a supercharger (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.
[0016]
As an intake system of the engine 1, an intake manifold 3 communicates with each intake port 2a, and a throttle chamber 5 in which a throttle valve 5a is interposed via an air chamber 4 in which intake passages of the respective cylinders gather in the intake manifold 3 is provided. It is communicated. An intercooler 6 is interposed upstream of the throttle chamber 5, and the intercooler 6 is communicated with a compressor 17 b of a turbocharger 17 as an example of a supercharger via an intake pipe 7. Further, an air cleaner 8 An air intake chamber 9 is communicated with the air intake chamber 9.
[0017]
Further, a bypass passage 10 for bypassing the throttle valve 5 a is provided in the throttle chamber 5, and an idle control valve that controls the idle speed by adjusting the amount of bypass air flowing through the bypass passage 10 in the bypass passage 10 ( ISC valve) 11 is interposed. Further, an injector 12 is disposed immediately upstream of the intake port 2 a of each cylinder of the intake manifold 3, and a spark plug 13 is disposed for each cylinder of the cylinder head 2. The spark plug 13 is connected to the secondary winding side of the igniter built-in ignition coil 14 (see FIG. 10).
[0018]
On the other hand, as an exhaust system of the engine 1, exhaust is joined by an exhaust manifold 15 communicating with each exhaust port 2 b of the cylinder head 2, and an exhaust pipe 16 is connected to the exhaust manifold 15. A turbine 17a of the turbocharger 17 is interposed in the exhaust pipe 16, and a catalyst 18 and a muffler 19 are disposed downstream of the exhaust pipe 16 and released to the atmosphere. In the turbocharger 17, a compressor 17b is rotationally driven by the energy of exhaust gas introduced into the turbine 17a and sucks and pressurizes air to supercharge, and a wastegate valve comprising a diaphragm actuator is provided on the turbine 17a side. A wastegate valve 21 having an actuating actuator 20 is provided.
[0019]
The actuator 20 for operating the wastegate valve is divided into two chambers by a diaphragm, one of which is a duty solenoid valve for boost pressure control. A pressure chamber communicating with the SOL is formed, and the other houses a spring that urges the wastegate valve 21 in the closing direction, and a spring chamber in which a rod that connects the diaphragm and the wastegate valve 21 is extended. The spring chamber is open to the atmosphere.
[0020]
In addition, a supercharging pressure control duty solenoid valve D.E. The SOL is a port communicating with the pressure chamber of the actuator 20 for operating the wastegate valve, the intake pipe 7 downstream of the compressor 17b of the turbocharger 17 via the orifice 22, and a port communicating with the intake pipe 7 upstream of the compressor 17b. The valve opening degree of the port communicating with the intake pipe 7 upstream of the compressor 17b is adjusted according to the duty ratio of the control signal output from the electronic control device 60 (see FIG. 10) described later. Then, the pressure on the upstream side and the pressure on the downstream side of the compressor 17b are regulated to supply the control pressure to the pressure chamber of the actuator 20 for operating the wastegate valve, and the opening degree of the wastegate valve 21 is adjusted to supercharge. The pressure is controlled.
[0021]
Here, the variable valve timing mechanism of the engine 1 will be described with reference to FIGS. The rotation of the crankshaft 23 of the engine 1 is caused by the crank pulley 26 fixed to the crankshaft 23, the timing of the intake camshaft 24 and the exhaust camshaft 25 respectively disposed in the cylinder heads 2 of the left and right banks. Transmission is performed via a belt 27, an intake cam pulley 28 interposed in the intake cam shaft 24, an exhaust cam pulley 29 fixed to the exhaust cam shaft 25, etc., and the crankshaft 23 and the cam shafts 24, 25 are two-to-one. The rotation angle is set. A cam 24a provided on the intake camshaft 24 and an exhaust cam (not shown) provided on the exhaust camshaft 25 are respectively maintained at a rotation angle of 2: 1 with the crankshaft 23. , 25, the intake valve 30 and the exhaust valve 31 are driven to open and close.
[0022]
As shown in FIG. 2, between the intake cam shafts 24 and the intake cam pulleys 28 in the left and right banks, the intake cam pulleys 28 and the intake cam shafts 24 are rotated relative to each other to rotate the intake cam shaft 24 with respect to the crankshaft 23. A hydraulically driven variable valve timing mechanism 32 that continuously changes the phase (displacement angle) is provided. As is well known, the variable valve timing mechanism 32 has its hydraulic pressure switched by an oil flow control valve 41R (41L) made up of a linear solenoid valve, a duty solenoid valve or the like, and an electronic control device 60 for engine control which will be described later. It operates by the drive signal from Note that the subscripts L and LH in each symbol represent the right bank, and the subscripts R and RH represent the left bank.
[0023]
The intake camshaft 24 is rotatably supported between the cylinder head 2 and a bearing cap (not shown), and has three vanes 33a at the tip of the intake camshaft 24 as shown in FIGS. A vane rotor 33 is attached by bolts 34 so as to be integrally rotatable. A housing 35 and a housing cover 36 are attached to the intake cam pulley 28 by bolts 37 so as to be integrally rotatable. In addition, a large number of external teeth 28 a for hooking the timing belt 27 are formed on the outer periphery of the intake cam pulley 28.
[0024]
The intake camshaft 24 passes through the housing cover 36 in a freely rotatable manner, and each vane 33a of the vane rotor 33 fixed to the intake camshaft 24 has three fan-like spaces formed in the housing 35 integral with the intake cam pulley 28. The part 38 is rotatably accommodated. Each fan-shaped space 38 is partitioned into an advance chamber 38a and a retard chamber 38b by vanes 33a.
[0025]
The advance chamber 38a is communicated with the A port 41a of the oil flow control valve 41R (41L) via the advance side oil passages 33b, 24b, 39 formed in the vane rotor 33, the intake camshaft 24, and the cylinder head 2, respectively. The retard chamber 38b is connected to the B port 41b of the oil flow control valve 41R (41L) via the retard angle side oil passages 33c, 24c, 40 formed in the vane rotor 33, the intake camshaft 24, and the cylinder head 2, respectively. It is communicated to.
[0026]
The oil flow control valve 41R (41L) includes an oil supply port 41c connected to an oil supply passage 45 to which oil, that is, a predetermined hydraulic pressure is supplied from an oil pan 42 via an oil pump 43 and an oil filter 44, and two drain passages. A port 41a, B is provided by reciprocating in the axial direction a spool 41g having drain ports 41d, 41f communicating with 46, 47 respectively, and having four lands and three passages formed between the lands. The port 41b is selectively communicated with the oil supply port 41c and the drain port 41d or 41f.
[0027]
In the present embodiment, the oil flow control valve 41R (41L) is a four-way control valve provided with a linear solenoid that is current-controlled by an electronic control device 60 described later as an actuator, and the spool 41g is proportional to the energization current of the linear solenoid. Moves in the axial direction, switches the oil flow direction and adjusts the opening of the passage to adjust the magnitude of the hydraulic pressure supplied to each advance chamber 38a and retard chamber 38b.
[0028]
Reference numeral 33d denotes a stopper pin inserted through the vane 33a of the vane rotor 33, and engages with a hole 35a formed in the housing 35 when the variable valve timing mechanism 32 is in the most retarded state (see FIG. 4). Position. 3 shows the most advanced angle state of the variable valve timing mechanism 32, and FIG. 4 shows the most retarded angle state of the variable valve timing mechanism 32.
[0029]
In the variable valve timing mechanism 32 described above, projections 48a, 48b, and 48c at predetermined crank angles on the outer periphery of the crank rotor 48 that is attached to the crankshaft 23 and rotates synchronously as sensors for detecting the operation position (see FIG. 6). ) And outputs a crank pulse representing the crank angle, and a plurality of protrusions 50a at equal angles on the outer periphery of the cam rotor 50 which is fixed to the rear end of the intake camshaft 24 and rotates synchronously. And a cam position sensor 51R (51L) that outputs a cam position pulse representing the cam position.
[0030]
The crank pulse output from the crank angle sensor 49 and the cam position pulse output from the cam position sensor 51R (51L) are input to the electronic control unit 60, and the electronic control unit 60 controls the crank pulse and the cam position. The displacement angle (actual valve timing) of the intake cam position with respect to the reference crank angle is calculated based on the pulse, and the variable valve timing mechanism 32 is fed back so that the actual valve timing converges to the target valve timing set based on the engine operating state. Control.
[0031]
In the present embodiment, the variable valve timing mechanism 32 is provided only on the intake camshaft 24 side, and the opening timing of the intake valve 30 is set according to the engine operating state with respect to the opening / closing timing of the exhaust valve 31, as shown in FIG. To change. Further, in the linear solenoid type oil flow control valve 41R (41L) employed in this embodiment, the spool 41g moves to the left as shown in FIG. 3 as the control current value output from the electronic control unit 60 increases. Thus, the displacement angle of the intake camshaft 24 relative to the crankshaft 23 is advanced, and the smaller the control current value, the more the spool 41g moves to the right as shown in FIG. Is retarded.
[0032]
That is, the crank pulse output from the crank angle sensor 49 and the cam position pulse output from the cam position sensor 51R (51L) with respect to the target displacement angle (target valve timing) set based on the engine operating state. Based on the rotation phase of the intake cam position with respect to the reference crank angle, that is, when the displacement angle of the intake cam shaft 24 with respect to the crankshaft 23 is advanced, the electronic control unit 60 outputs to the oil flow control valve 41R (41L). When the displacement angle of the intake camshaft 24 relative to the crankshaft 23 is retarded by decreasing the control current value and operating the variable valve timing mechanism 32, the displacement angle of the intake camshaft 24 relative to the crankshaft 23 is retarded. Variable valve timing by increasing the control current value output to the oil flow control valve 41R (41L) Advancing the displacement angle of the intake camshaft 24 relative to the crankshaft 23 by the operation of the structure 32.
[0033]
When the control current value of the oil flow control valve 41R (41L) increases, the spool 41g moves to the left as shown in FIG. 3, and the A port 41a and the oil supply port 41c communicate with each other so that the variable valve timing mechanism 32 The advance chamber 38a communicates with the oil supply passage 45 via the advance side oil passages 33b, 24b, 39 and the oil flow control valve 41R (41L). At the same time, the B port 41b and the drain port 41f communicate with each other, so that the retard chamber 38b of the variable valve timing mechanism 32 connects the retard side oil passages 33c, 24c, 40, and the oil flow control valve 41R (41L). To the drain passage 47.
[0034]
As a result, oil is supplied to the advance chamber 38a of the variable valve timing mechanism 32 to increase the hydraulic pressure acting on the advance chamber 38a, and the hydraulic pressure acting on the retard chamber 38b by the drain of oil in the retard chamber 38b. As shown in FIG. 3, the vane rotor 33 rotates in the clockwise direction in the figure, and the rotational phase of the intake camshaft 24 relative to the intake cam pulley 28, that is, the displacement angle of the intake camshaft 24 relative to the crankshaft 23 advances. The opening / closing timing of the intake valve 30 driven by the intake cam 24a of the intake cam shaft 24 is advanced by being angulated.
[0035]
Conversely, when the control current value of the oil flow control valve 41R (41L) decreases, the spool 41g moves to the right as shown in FIG. 4, and the A port 41a and the drain port 41d communicate with each other to change the valve timing mechanism. The 32 advance chambers 38a communicate with the drain passage 46 via the advance side oil passages 33b, 24b, 39 and the oil flow control valve 41R (41L). At the same time, the B port 41b and the oil supply port 41c communicate with each other, so that the retard chamber 38b of the variable valve timing mechanism 32 becomes the retard oil passages 33c, 24c, 40, and the oil flow control valve 41R (41L). Through the oil supply passage 45.
[0036]
As a result, the hydraulic pressure acting on the advance chamber 38a is reduced by the drain of oil in the advance chamber 38a of the variable valve timing mechanism 32, and the oil pressure is supplied to the retard chamber 38b and acts on the retard chamber 38b. As shown in FIG. 4, the vane rotor 33 rotates counterclockwise in the figure, and the rotational phase of the intake cam shaft 24 with respect to the intake cam pulley 28, that is, the displacement angle of the intake cam shaft 24 with respect to the crankshaft 23. The opening / closing timing of the intake valve 30 driven by the intake cam 24a of the intake cam shaft 24 is delayed by being retarded.
[0037]
Next, sensors for detecting the engine operating state will be described. A thermal intake air amount sensor 52 using a hot wire or a hot film is interposed immediately downstream of the air cleaner 8 of the intake pipe 7. A throttle opening sensor 53 is connected to a throttle valve 5 a provided in the throttle chamber 5, and an intake pipe pressure sensor 54 is exposed to the air chamber 4. Further, a knock sensor 55 is attached to the cylinder block 1a of the engine 1, and a cooling water temperature sensor 56 is exposed to the cooling water passage 1b communicating with both the left and right banks of the cylinder block 1a.
[0038]
In addition, an air-fuel ratio sensor 57 is disposed at a junction where the exhaust manifolds 15 of the banks merge, and a crank angle sensor 49 is provided on the outer periphery of a crank rotor 48 that is attached to the crankshaft 23 of the engine 1. A cylinder discrimination sensor 58 is provided on the back surface of the intake cam pulley 28 that rotates 1/2 with respect to the crankshaft 23 (see FIG. 2). Further, a cam position sensor 51R (51L) is provided on the outer periphery of the cam rotor 50 fixed to the rear end of the intake camshaft 24.
[0039]
As shown in FIG. 6, the crank rotor 48 has protrusions 48a, 48b, 48c formed on the outer periphery thereof, and these protrusions 48a, 48b, 48c are connected to the cylinders (# 1, # 2 cylinders and # 3, # 3). (4-cylinder) before compression top dead center (BTDC) θ1, θ2, and θ3. In this embodiment, θ1 = 97 ° CA, θ2 = 65 ° CA, and θ3 = 10 ° CA.
[0040]
Further, as shown in FIG. 7, cylinder discriminating projections 28b, 28c, 28d are formed on the outer peripheral side of the back surface of the intake cam pulley 28, and the projection 28b is located after compression top dead center (ATDC) of the # 3 and # 4 cylinders. ) Formed at the position of θ4, the protrusion 28c is composed of three protrusions, and the first protrusion is formed at the position of ATDC θ5 of the # 1 cylinder. Further, the protrusion 28d is formed by two protrusions, and the first protrusion is formed at the position of ATDCθ6 of the # 2 cylinder. In this embodiment, θ4 = 20 ° CA, θ5 = 5 ° CA, and θ6 = 20 ° CA. The cylinder discrimination protrusions 28b, 28c, 28d and the cylinder discrimination sensor 58 are provided only in one bank.
[0041]
Further, corresponding to the fact that the engine 1 employed in this embodiment is a four-cylinder engine, the cam rotor 50 has cam position detection protrusions 50a on the outer periphery thereof at equal angles of 180 ° CA as shown in FIG. A total of four are formed one by one. The projections 50a change between θ7 = BTDC 40 ° CA and ATDC 10 ° CA with the compression top dead center of each cylinder as a reference by the operation of the variable valve timing mechanism 32.
[0042]
8 shows the cam rotor 50 fixed to the intake camshaft 24 on the RH side, the cam rotor 50 is similarly fixed to the intake camshaft 24 on the LH side, and a cam position is provided on the outer periphery thereof. Four detection projections 50a are formed at an equal angle of 180 ° CA. These projections 50a are operated by the variable valve timing mechanism 32 and θ8 = BTDC 40 with reference to the compression top dead center of each cylinder. It varies between ° CA and ATDC10 ° CA.
[0043]
Then, as shown in the time chart of FIG. 9, the crank rotor 48 and the cam rotor 50 are rotated by the rotation of the crankshaft 23, the intake cam pulley 28, and the intake camshaft 24 in accordance with the engine operation. The protrusions 48a, 48b, and 48c are detected by the crank angle sensor 49, and each crank pulse of θ1, θ2, and θ3 (BTDC 97 °, 65 °, 10 ° CA) is detected from the crank angle sensor 49 by 1/2 engine rotation (180 ° CA). ) Is output every time.
[0044]
Further, the projections 28b, 28c, 28d of the intake cam pulley 28 are detected by the cylinder discrimination sensor 58 between the θ3 crank pulse and the θ1 crank pulse, and a predetermined number of cylinder discrimination pulses are output from the cylinder discrimination sensor 58. Further, each protrusion 50a of the cam rotor 50 fixed to the rear end of each intake camshaft 24 of the right bank and the left bank whose rotational phase is changed with respect to the crankshaft 23 by the variable valve timing mechanism 32 is provided with cam position sensors 51R and 51L. And cam position pulses of θ7 and θ8 are output from the cam position sensors 51R and 51L, respectively.
[0045]
Then, in the following electronic control unit (hereinafter abbreviated as “ECU”) 60, the engine speed NE is calculated based on the input interval time of the crank pulse output from the crank angle sensor 49, and each cylinder Based on the pattern of the combustion stroke order (for example, # 1 cylinder → # 3 cylinder → # 2 cylinder → # 4 cylinder) and the value obtained by counting the cylinder discrimination pulse from the cylinder discrimination sensor 58 by the counter, Cylinder discrimination of the fuel injection target cylinder and the ignition target cylinder is performed. Further, the ECU 60 is based on the crank pulse output from the crank angle sensor 49 (for example, the θ2 crank pulse corresponding to the protrusion 48b) and the θ7 and θ8 cam position pulses output from the cam position sensors 51R and 51L. An actual displacement angle (actual valve timing) of the intake cam position with respect to the reference crank angle is calculated.
[0046]
The ECU 60 processes signals from the various sensors and switches described above to calculate control amounts for the various actuators, and performs fuel injection control, ignition timing control, idle speed control, supercharging pressure control, and valve for the intake valve 30. Timing control and the like are performed. As shown in FIG. 10, the ECU 60 is composed mainly of a microcomputer to which a CPU 61, ROM 62, RAM 63, backup RAM 64, counter / timer group 65, and I / O interface 66 are connected via a bus line. Peripheral circuits such as a constant voltage circuit 67 for supplying a power source, a drive circuit 68 connected to the I / O interface 66, and an A / D converter 69 are incorporated.
[0047]
The counter / timer group 65 includes a free-run counter, various counters such as a cylinder discrimination sensor signal (cylinder discrimination pulse) counting counter, a fuel injection timer, an ignition timer, and a periodic interrupt for generating a periodic interrupt. Timers, timers for interval measurement of crank angle sensor signals (crank pulses), watchdog timers for system abnormality monitoring, etc. are collectively referred to for convenience, and other software counters and timers are used. It is done.
[0048]
The constant voltage circuit 67 is connected to the battery 71 via a first relay contact of a power supply relay 70 having two relay contacts. In the power supply relay 70, one end of the relay coil is 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.
[0049]
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. 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.
[0050]
The input port of the I / O interface 66 is connected to a knock sensor 55, a crank angle sensor 49, a cylinder discrimination sensor 58, cam position sensors 51R and 51L, a vehicle speed sensor 59 for detecting the vehicle speed, and the like. Via an A / D converter 69, an intake air amount sensor 52, a throttle opening sensor 53, an intake pipe pressure sensor 54, a cooling water temperature sensor 56, an air-fuel ratio sensor 57, and the like are connected, and a battery voltage VB is input. Monitored. On the other hand, the output port of the I / O interface 66 includes an ISC valve 11, an injector 12, a supercharging pressure control duty solenoid valve D.P. The SOL, oil flow control valves 41R and 41L, and the relay coil of the power supply relay 70 are connected via a drive circuit 68, and the ignition coil 14 with a built-in igniter is connected.
[0051]
The CPU 61 processes detection signals from the sensors and switches, the battery voltage, and the like input via the I / O interface 66 according to a control program stored in the ROM 62, and stores various data stored in the RAM 63, and Based on various learning value data stored in the backup RAM 64, fixed data stored in the ROM 62, etc., the injector 12, the igniter built-in ignition coil 14, the ISC valve 11, the supercharging pressure control duty solenoid valve D.E. Control amounts for the SOL, oil flow control valves 41R, 41L, etc. are calculated, and engine control such as fuel injection control, ignition timing control, ISC control, supercharging pressure control, valve timing control, etc. is performed.
[0052]
Here, in the fuel injection control by the ECU, the fuel injection timing set based on the engine load and the engine speed is set to the intake valve 30 and the exhaust valve 31 together by the valve timing control via the variable valve timing mechanism 32. The angle is retarded in consideration of the valve overlap amount to be opened and the supercharging pressure by supercharging pressure control via the turbocharger 17. Then, as the valve overlap amount is larger and the boost pressure is higher, the fuel injection timing is retarded, thereby preventing the air-fuel mixture from blowing through from the intake side to the exhaust side.
[0053]
That is, the ECU 60 realizes functions as fuel injection timing setting means and fuel injection timing retarding means according to the present invention. Hereinafter, processing related to retarding the fuel injection timing by the ECU 60 will be described with reference to flowcharts shown in FIGS.
[0054]
FIG. 11 is a valve timing control routine executed by the ECU 60 at predetermined intervals (predetermined times). In this routine, first, in step S101, the basic fuel injection pulse width Tp as the engine load and the engine speed NE are set. Based on the table, the target valve timing (target displacement angle) VTTGT is set by interpolation calculation (VTTTGT ← TBL (Tp, NE)).
[0055]
As shown in FIG. 12, in the valve timing control, the engine 1 is controlled to an optimum state by setting the target valve timing VTTGT for each of the four control regions according to the operating state depending on the engine load and the engine speed. In the low load and low rotation idling region, the target valve timing VTTGT is set to 0 °, and the opening / closing timing of the intake valve 30 is controlled to the most retarded state with the advance amount = 0 °. And the intake valve 30 are eliminated to stabilize the idling rotation.
[0056]
In the middle load operation region, the target valve timing VTTGT is set to a small to medium advance amount, the opening / closing timing of the intake valve 30 is controlled to the advance side, and the overlap amount between the exhaust valve 31 and the intake valve 30 is controlled. Is increased to increase the internal EGR rate, thereby reducing engine pumping loss and improving fuel efficiency. In the high load operation region, the target valve timing VTTGT is set to a large advance amount, and the opening / closing timing of the intake valve 30 is controlled to the advance side with respect to the medium load region, and the overlap amount between the exhaust valve 31 and the intake valve 30 is controlled. Is further increased to increase the charging efficiency and scavenging efficiency and improve the engine output. Further, in the low-load high-rotation operation region, the target valve timing VTTGT is set to a small advance amount so that the opening / closing timing of the intake valve 30 is controlled to the retard side, thereby reducing the valve overlap amount to prevent engine overspeed. .
[0057]
Then, after setting the target valve timing VTTGT in step 101, the process proceeds to step S102, where the crankshaft is driven based on the crank pulse output from the crank angle sensor 49 and the cam position pulse output from the cam position sensor 51R (51L). The actual valve timing (actual displacement angle) VT of the intake camshaft 24 with respect to 23 is calculated. Specifically, the actual valve timing VT is calculated by calculating the rotation time per unit angle from the engine speed NE calculated by the crank pulse, and the θ2 crank pulse is input to the time per unit angle rotation. Is multiplied by the time from when the θ7, θ8 cam position pulse is input, to the rotational phase of the intake cam position relative to the reference crank angle by the θ2 crank pulse, that is, the displacement angle VT of the intake camshaft 24 relative to the crankshaft 23. Is done.
[0058]
Next, the process proceeds to step S103, and the feedback current value (K × (VTTTGT−) obtained by multiplying the holding current value IVTH of the oil flow control valve 41R (41L) by the proportional gain K to the deviation between the target valve timing VTTGT and the actual valve timing VT. VT)) is added to calculate the control current value IVT of the oil flow control valve 41R (41L). In step S104, the control current value IVT is set to output the control current based on the control current value IVT to the oil flow control valve 41R (41L) via the drive circuit 68, and the routine is exited.
[0059]
The holding current value IVTH holds the spool 41g of the oil flow control valve 41R (41L) at a position that closes the A port 41a and the B port 41b with the land, and advances the oil passage on the cylinder head 2 side. 39. By blocking the retard side oil passage 40 from the oil supply port 41c and drain ports 41d and 41f of the oil flow control valve 41L (41R), the vane rotor 33 of the variable valve timing mechanism 32 is also retarded to the advance side. It is a current value for maintaining a steady state converged at a predetermined target valve timing without being displaced also on the corner side, and is learned for each oil flow control valve 41R (41L) of an individual control system.
[0060]
The control current value IVT of the oil flow control valve 41R (41L) is a feedback current value (K × (VTTTGT−VT) corresponding to a deviation between the target valve timing VTTGT and the actual valve timing VT with respect to the holding current value IVTH. ) (For example, IVT = 100 mA to 1000 mA), the stroke of the spool 41g is changed, the amount of connection between the advance side oil passage 39 or the retard side oil passage 40 and the oil supply passage 45, and the advance side oil. The amount of connection between the passage 39 or the retarded-side oil passage 40 and the drain passages 46 and 47 is changed between 0 and 100%, and feedback control is performed so that the actual valve timing VT converges to the target valve timing VTTGT.
[0061]
That is, when the actual valve timing VT is retarded with respect to the target valve timing VTTGT, the control current value IVT of the oil flow control valve 41R (41L) is increased, and the spool 41g is supplied to the advance side oil passage 39 and the oil supply. The amount of connection with the passage 45 and the amount of connection between the retard angle side oil passage 40 and the drain passage 47 are increased. As a result, the hydraulic pressure in the advance chamber 38a of the variable valve timing mechanism 32 increases and the hydraulic pressure in the retard chamber 38b decreases, and the vane rotor 33 rotates in the clockwise direction (see FIG. 3). The rotational phase of the cam shaft 24, that is, the rotational phase (displacement angle) of the intake cam shaft 24 relative to the crank shaft 23 is advanced, and the opening / closing timing of the intake valve 30 driven by the intake cam 24a of the intake cam shaft 24 is advanced. The
[0062]
Conversely, when the actual valve timing VT is advanced with respect to the target valve timing VTTGT, the control current value IVT of the oil flow control valve 41R (41L) is decreased and the spool 41g is retarded by the retarded oil passage 40. And the oil supply passage 45 and the connection amount between the advance side oil passage 39 and the drain passage 46 are increased. As a result, the hydraulic pressure in the advance chamber 38a of the advance chamber 38a of the variable valve timing mechanism 32 decreases and the hydraulic pressure in the retard chamber 38b increases, and the vane rotor 33 rotates counterclockwise (see FIG. 4). The rotation phase of the intake camshaft 24 relative to the intake cam pulley 28, that is, the rotation phase (displacement angle) of the intake camshaft 24 relative to the crankshaft 23 is retarded, and the intake valve 30 driven by the intake cam 24a of the intake camshaft 24 The opening and closing timing is retarded.
[0063]
When the actual valve timing VT converges to the target valve timing VTTGT (VTTGT = VT), the feedback current value becomes 0, and the spool 41g of the oil flow control valve 41R (41L) moves to the advance side oil passage 39 and the retard side. The oil passage 40 is moved to a position where it is closed, and the vane rotor 33 of the variable valve timing mechanism 32 is stopped and held.
[0064]
As a result of the above valve timing control, when the valve overlap amount increases in the middle / high load operation range, in response to this, in fuel injection control, the larger the valve overlap amount and the higher the boost pressure, the higher the fuel injection. Delay the time. Hereinafter, processing related to fuel injection control will be described.
[0065]
FIG. 13 is a fuel injection amount / injection timing setting routine executed every predetermined period (predetermined time). First, in step S201, the basic fuel injection amount is determined based on the intake air amount Q and the engine speed NE. A basic fuel injection pulse width Tp to be determined is calculated (Tp ← K × Q / NE; K is an injector characteristic correction constant). In step S202, the basic fuel injection pulse width Tp is multiplied by various correction terms and added to the engine. A fuel injection pulse width Ti that determines the final fuel injection amount is calculated. Examples of correction multiplication terms for the basic fuel injection pulse width Tp include various correction coefficients COEF related to cooling water temperature correction, acceleration / deceleration correction, full-open increase correction, post-idle increase correction, etc., and air-fuel ratio correction based on the output of the air-fuel ratio sensor 57 An air-fuel ratio feedback correction coefficient α, an air-fuel ratio learning correction coefficient KBLRC for correcting variations in production of the intake air amount measurement system such as the intake air amount sensor 52 and fuel supply system such as the injector 12 and deterioration over time, etc. There is a fuel cut coefficient KFC for fuel cut, and the correction addition term includes a voltage correction pulse width Ts for correcting the invalid injection time of the injector 12 that changes according to the battery voltage VB. Then, the final fuel injection pulse width Ti is calculated from these correction terms (Ti ← Tp × COEF × α × KBLRC × KFC + Ts).
[0066]
Next, the process proceeds to step S203, and the basic fuel injection start injection timing INJSTB is set by referring to the table with interpolation calculation based on the fuel injection pulse width Ti as the engine load and the engine speed NE (INJSTB ← TBL (Ti , NE) As shown in Fig. 14, the basic fuel injection start injection timing INJSTB increases the air utilization rate for each operating region with the engine speed NE and the fuel injection pulse width Ti as parameters. The optimum injection start timing for obtaining good mixing with the fuel is obtained in advance from simulations or experiments, and the injection start timing is advanced as the shift from the low load range to the high load range is made.
[0067]
In the following step S204, the valve overlap amount VOR is calculated based on the actual valve timing VT, and in step S205, the table is calculated based on the valve overlap amount VOR and the actual boost pressure P sensed by the intake pipe pressure sensor 54. The injection timing retardation amount RINJ is set with reference to the interpolation calculation (RINJ ← TBL (VOR, P)). As shown in FIG. 15, the injection timing retardation amount RINJ prevents the air-fuel mixture from blowing through from the intake side to the exhaust side in each operation region using the valve overlap amount VOR and the actual boost pressure P as parameters. In other words, an appropriate delay amount is obtained in advance from simulation or experiment. Since the influence of the blow-through is smaller in the region where the valve overlap amount VOR is smaller and the actual boost pressure P is lower, the injection timing retard amount RINJ is The smaller the valve overlap amount VOR is, and the higher the actual supercharging pressure P is, the larger the influence of the blow-through is, so the injection timing retard amount RINJ is increased.
[0068]
Thereafter, the process proceeds to step S206, where the final fuel injection start timing INJST is set by adding the injection timing retard amount RINJ to the basic fuel injection start timing INJSTB (INJST ← INJSTB + RINJ). In this embodiment, a time control method is adopted, and the fuel injection start timing for the corresponding cylinder is controlled by the time after the input of the θ1 crank pulse. Therefore, the injection timing retard amount RINJ is added to the basic fuel injection start timing INJSTB as an addition term. As a result, the fuel injection start timing is retarded. In steps S207 and S208, the fuel injection start timing INJST and the fuel injection pulse width Ti are set in the injection timer, and the routine is exited.
[0069]
When the time measurement by the injection timer starts and the fuel injection start timing INJST is reached, the INJST interrupt routine of FIG. 16 is started. In this routine, in step S301, a drive signal having a fuel injection pulse width Ti is output to the injector 12 to start fuel injection from the injector 12, and the routine is exited.
[0070]
That is, as indicated by a broken line in the time chart of FIG. 9, the fuel injection timing based on the fuel injection pulse width Ti output to the injector 12 is set as the fuel injection timing set based on the engine load and the engine speed, and the valve overlap amount is set. The angle is retarded according to. As a result, it is possible to prevent the exhaust gas from being blown back at the time of valve overlap and to continue proper fuel injection, and to avoid deposit accumulation on the injection port of the injector 12 and thermal damage around the injector 12 and the injection port. , Exhaust emissions and fuel consumption can be prevented from deteriorating.
[0071]
17 to 20 relate to a second embodiment of the present invention, FIG. 17 is a flowchart of a fuel injection amount / injection timing setting routine, FIG. 18 is an explanatory diagram of a first correction coefficient, and FIG. 19 is a second correction. FIG. 20 is an explanatory diagram of a third correction coefficient.
[0072]
In the second mode, the fuel injection timing is controlled more precisely by correcting the injection timing retard amount RINJ in accordance with the operating state such as the opening degree of the wastegate valve 21, the opening degree of the throttle valve 5a, and the engine speed. It is. For this reason, in the second embodiment, some processing is added to the fuel injection amount / injection timing setting routine (see FIG. 13) of the first embodiment.
[0073]
That is, as shown in FIG. 17, in the fuel injection amount / injection timing setting routine of the second embodiment, the routine proceeds to steps S205-1 through steps S201 to S205 described in the first embodiment, and the opening degree of the wastegate valve 21 is set. Corresponding supercharging pressure control duty solenoid valve Based on the control amount for the SOL (duty ratio DUTY in this embodiment), the table is referred to with interpolation calculation, and a first correction coefficient R1 for correcting the injection timing retardation amount RINJ is set appropriately.
[0074]
Since the turbine efficiency of the turbocharger 17 decreases as the opening degree of the wastegate valve 21 increases, the first correction coefficient R1 increases the exhaust pressure to obtain the same supercharging pressure, so Duty solenoid valve for boost pressure control D.D. An appropriate correction factor for the injection timing retardation amount RINJ is obtained in advance by simulation or experiment using the duty ratio DUTY of the control signal for SOL as a parameter. That is, as shown in FIG. The duty ratio DUTY of the control signal with respect to SOL is equal to or less than the set value (the opening degree of the wastegate valve 21 is equal to or less than the set opening degree), and R1 = 1 without substantial correction. As the duty ratio DUTY of the control signal with respect to SOL increases (as the opening degree of the wastegate valve 21 increases), 1> R1 is set to prevent an excessive delay of the fuel injection timing.
[0075]
Next, the process proceeds from step S205-1 to step S205-2, and a second correction coefficient R2 for correcting the injection timing retard amount RINJ by an appropriate rate by referring to the table with interpolation calculation based on the throttle opening THV. Set. The second correction coefficient R2 takes into account that the smaller the opening of the throttle valve 5a, the higher the pressure on the upstream side of the throttle valve 5a, the higher the exhaust pressure, and the smaller the influence of blow-through. As a parameter, an appropriate correction factor for the injection timing retardation amount RINJ is obtained in advance by simulation or experiment. That is, as shown in FIG. 19, R2 = 1 without substantial correction at the set throttle opening, and as the throttle opening decreases, 1> R2 and an excessive retardation of the fuel injection timing is prevented.
[0076]
In the subsequent step S205-3, the table is referred to with interpolation calculation based on the engine speed NE, and a third correction coefficient R3 for correcting the injection timing retardation amount RINJ is set appropriately. The third correction coefficient R3 is injected by simulation or experiment in advance using the engine speed NE as a parameter, considering that the exhaust pulsation changes depending on the engine speed and the amount of blow-through from the intake side to the exhaust side changes. An appropriate correction factor for the timing retardation amount RINJ is obtained. That is, as shown in FIG. 20, with respect to R3 = 1 without substantial correction, as the engine speed NE increases, 1> R3 is set to prevent the fuel injection timing from being excessively retarded.
[0077]
Thereafter, the process proceeds to step S205-4, and the injection timing retardation amount RINJ is multiplied by the first, second, and third correction coefficients R1, R2, and R3 to correct the injection timing retardation amount RINJ (RINJ ← RINJ × R1 × R2 × R3). Then, the process proceeds from step S205-4 to step S206, and the final fuel injection start timing INJST is set by adding the corrected injection timing retard amount RINJ to the basic fuel injection start timing INJSTB (INJST ← INJSTB + RINJ). In S207 and S208, the fuel injection start timing INJST and the fuel injection pulse width Ti are set in the injection timer, and the routine is exited.
[0078]
In the second mode, as in the first mode described above, not only can the exhaust blow-back at the time of valve overlap be prevented and proper fuel injection can be continued, but also the pressure conditions on the intake and exhaust sides can be taken into account. In addition, the amount of retardation of the fuel injection timing can be set more precisely, and the controllability can be improved.
[0079]
The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. For example, in each embodiment, the fuel injection timing is set based on the fuel injection start timing. However, the fuel injection start timing is determined based on the fuel injection end timing, and the fuel injection start is calculated from the fuel injection end timing by the fuel injection pulse width. You may set the time.
[0080]
In each of the embodiments, the example in which the variable valve timing mechanism is disposed only on the intake camshaft side has been described. However, the present invention is not limited to this, and the variable valve timing mechanism is used as the intake camshaft. What is necessary is just to arrange | position to at least one side with an exhaust camshaft.
[0081]
Furthermore, in each embodiment, the example applied to an engine with a continuously variable valve timing mechanism has been described. However, the present invention is not limited to this, and a variable valve timing mechanism is disclosed in JP-A-7-11981. It is also possible to apply to a device that selectively switches between a low speed cam and a high speed cam.
[0082]
【The invention's effect】
As described above, according to the present invention, it is possible to appropriately retard the fuel injection timing in accordance with the valve overlap amount and the boost pressure, thereby preventing the air-fuel mixture from blowing through from the intake side to the exhaust side. In addition, it is possible to avoid deposit accumulation at the injection port of the injector and thermal damage around the injector and the injection port.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a variable valve timing mechanism and an engine with a supercharger according to a first embodiment of the present invention.
FIG. 2 is a schematic configuration diagram of the 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 diagram showing the most retarded angle state of the variable valve timing mechanism in the AA cross section of FIG. 2;
FIG. 5 is an explanatory diagram showing a change in valve timing of the intake valve with respect to the exhaust valve;
FIG. 6 is a front view of the crank rotor and the crank angle sensor.
FIG. 7 is a rear view of the intake cam pulley.
FIG. 8 is a front view of the cam rotor and the cam position sensor.
FIG. 9 is a time chart showing the relationship between a crank pulse, a cylinder discrimination pulse, and a cam position pulse.
FIG. 10 is a circuit configuration diagram of the electronic control system as above.
FIG. 11 is a flowchart of a valve timing control routine as above.
FIG. 12 is an explanatory diagram showing a valve timing control region as above;
FIG. 13 is a flowchart of a fuel injection amount / injection timing setting routine;
FIG. 14 is an explanatory diagram of basic fuel injection start timing
FIG. 15 is an explanatory diagram of the injection timing retardation amount as above.
FIG. 16 is a flowchart of the INJST interrupt routine.
FIG. 17 is a flowchart of a fuel injection amount / injection timing setting routine according to the second embodiment of the present invention.
FIG. 18 is a diagram for explaining the first correction coefficient, same as above.
FIG. 19 is an explanatory diagram of the second correction coefficient, same as above.
FIG. 20 is a diagram for explaining the third correction coefficient, same as above.
[Explanation of symbols]
1 Variable valve timing mechanism and turbocharged engine
17 Turbocharger (supercharger)
30 Intake valve
31 Exhaust valve
32 Variable valve timing mechanism
60 Electronic control unit (fuel injection timing setting means, fuel injection timing retarding means)
NE engine speed
VOR Valve overlap amount
P Supercharging pressure
INJST Fuel injection start time
RINJ Injection timing retard amount
DUTY Duty ratio (opening degree of control valve for controlling supercharging pressure)
THV throttle opening (throttle valve opening)
R1 first correction factor
R2 Second correction factor
R3 Third correction factor

Claims (2)

A variable valve timing mechanism having a variable valve timing mechanism and a supercharger for varying the opening and closing timing of at least one of an intake valve and an exhaust valve, and a fuel injection control device for a supercharged engine,
Fuel injection timing setting means for setting the fuel injection timing based on the engine load and the engine speed;
Sets the retard amount of the fuel injection timing based on the supercharging pressure by the valve overlap amount and the supercharger of the intake and exhaust valves are varied by the variable valve timing mechanism, over by the supercharger The retardation amount is corrected by a first correction coefficient that decreases as the opening of the control valve for controlling the supply pressure increases or a second correction coefficient that decreases as the opening of the throttle valve decreases. A variable valve timing mechanism comprising fuel injection timing retarding means for retarding the fuel injection timing set by the fuel injection timing setting means as the overlap amount is large and the boost pressure is high And a fuel injection control device for a supercharged engine. The fuel injection timing retard means is a variable valve according to claim 1, wherein setting the third correction coefficient based on the engine speed, by the third correction coefficient and corrects the retard amount A fuel injection control device for a timing mechanism and a supercharged engine.

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