JPH04287846A - Control method of engine with variable valve timing device - Google Patents

Abstract

PURPOSE:To compensate the mechanical operation delay of a variable valve timing device during acceleration so as to eliminate the response delay of valve timing control. CONSTITUTION:A variable valve timing device(VVT) for changing the operating timing of an intake valve 9 is formed of a timing pulley assembly 23 and a step motor 24. At the accelerating time of an engine 1, an ECU 42 controls the VVT so as to advance the closing timing of the intake valve 9, and determines the fuel injection quantity in such a way as to further increase the fuel supply quantity set by various parameters such as engine speed and intake pressure to perform the control of an injector 11 on the basis of this fuel injection quantity. At the accelerating time, the quantity increased fuel is supplied to a combustion chamber 6, and the output of the engine 1 is increased with more speed and smoothness by this increased quantity part, so that mechanical operation delay that cannot be compensated only by the VVT itself can be compensated appropriately.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine equipped with a variable valve timing device that varies the opening and closing timing of an intake valve during operation, and more particularly to a control method for compensating for a delay in the operation of a variable valve timing device during acceleration. It is something.

0002

2. Description of the Related Art Hitherto, as a technique of this type, there has been known an "engine valve timing control device" disclosed in, for example, Japanese Patent Application Laid-open No. 190610/1983. This control device includes a variable valve timing device that changes the closing timing of the intake valve. In particular, when the engine accelerates, there is a mechanical delay in the operation of the variable valve timing device, so in order to compensate for this delay in operation, the control target value of the variable valve timing device during acceleration is set to the control target value in the steady operating state. I was trying to set it larger than that. In other words, the variable valve timing device is controlled to hasten the time it takes to reach its target control timing, thereby improving the responsiveness of the intake valve closing timing during acceleration.

0003

[Problems to be Solved by the Invention] However, in the prior art described above, although the control target value of the variable valve timing device is set to a large value during acceleration, the variable valve timing device inherently has mechanical A delay in operation remains. As a result, there remained a delay in the rise of the engine intake air amount, resulting in poor acceleration feeling. Therefore, simply devising control of the variable valve timing device itself has not been a sufficient measure against the delay in operation.

The present invention has been made in view of the above-mentioned circumstances, and its object is to properly compensate for the mechanical operation delay that cannot be compensated for by the variable valve timing device itself during acceleration, and to adjust the valve timing. An object of the present invention is to provide a control method for an engine equipped with a variable valve timing device that can eliminate control response delays.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an intake valve for opening and closing an intake passage leading to a combustion chamber of an engine, a fuel supply means for supplying fuel to the combustion chamber, In a method for controlling an engine equipped with a variable valve timing device, the variable valve timing device is provided with a variable valve timing device that varies the opening and closing timing of an intake valve, and the variable valve timing device is controlled to advance the closing timing of the intake valve when the engine accelerates.
When accelerating the engine, the fuel supply means is controlled so that the amount of fuel supplied is further increased than the amount of fuel supplied based on various parameters of the operating state.

[0006]

[Operation] According to the above configuration, the closing timing of the intake valve is advanced by the control of the variable valve timing device when the engine accelerates, but there remains a mechanical delay in operation that cannot be compensated for by the variable valve timing device itself. . At this time, the fuel supply amount from the fuel supply means is further increased than the fuel supply amount set by various parameters of the engine operating state and is supplied to the combustion chamber, so the engine output increases immediately by the increased amount. This compensates for the mechanical delay in actuation of the variable valve timing device.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the method of controlling an engine equipped with a variable valve timing device according to the present invention will be described in detail below with reference to FIGS. 1 to 6. FIG. 1 is a schematic configuration diagram (only one cylinder is shown) for explaining a gasoline engine 1 of this embodiment. Engine 1 cylinder bore 2
A piston 3 is provided to be movable up and down. The piston 3 is connected to a crankshaft (not shown) via a rod 4. And piston 3, cylinder bore 2
A space surrounded by a cylinder head 5 covering the upper part of the bore 2 is a combustion chamber 6.

The combustion chamber 6 is provided with an intake passage 7 and an exhaust passage 8 which communicate with each other. An intake valve 9 for opening and closing is assembled into an intake port 7a of the intake passage 7 that opens into the combustion chamber 6. Further, an exhaust port 8a of the exhaust passage 8 that opens into the combustion chamber 6 is provided with an exhaust valve 10 for opening and closing.
is assembled. Outside air is introduced into the intake passage 7 via an air cleaner (not shown). Further, the intake passage 7 is provided with a fuel injector 11 as a fuel supply means near the intake port 7a, so that fuel is taken into the intake passage 7. As is well known, fuel at a predetermined pressure is supplied to the injector 11 from a fuel tank (not shown) by the operation of a fuel pump. Then, when the intake valve 9 is opened, the mixture of fuel and outside air taken into the intake passage 7 is introduced into the combustion chamber 6 through the intake port 7a. Furthermore, the air-fuel mixture introduced into the combustion chamber 6 is exploded and burned, thereby providing driving force for the engine 1 via the piston 3, crankshaft, and the like. Furthermore, the combustion chamber 6
When the exhaust valve 10 is opened, the burned gas is discharged from the exhaust port 8a to the outside through the exhaust passage 8.

In the middle of the intake passage 7, there is an accelerator pedal 1.
A throttle valve 13 is provided which is opened and closed in conjunction with the operation of step 2. By opening and closing the throttle valve 13, the amount of intake air into the intake passage 7 is adjusted. Further, a throttle sensor 14 is provided near the throttle valve 13 to detect the throttle opening TA. Furthermore, a surge tank 15 is provided downstream of the throttle valve 13 to smooth out pulsations in the intake air. This surge tank 15 is provided with an intake pressure sensor 16 that communicates with the tank 15 and detects intake air pressure (intake pressure) PM.

[0010] The valve train mechanism will be explained. Intake valve 9
and the exhaust valve 10 each have a stem 9a extending upward.
, 10a, and valve springs 17, 18, valve lifters 19, 20, etc. are assembled to the upper part of each stem 9a, 10a, respectively. Each valve lifter 19,
20 is provided with cams 21a and 22a to engage with each other. These cams 21a and 22a are formed on the intake side camshaft 21 supported by the cylinder head 5 and on the exhaust side camshaft 22, the number of which corresponds to all the cylinders. The intake valve 9 and the exhaust valve 10 are urged upward by the urging force of the valve springs 17 and 18 in a direction that closes the intake port 7a and the exhaust port 8a. In this biased state, the upper end of each stem 9a, 10a is connected to the valve lifter 19, 2.
0 and is always in contact with the cams 21a and 22a.

In this embodiment, the camshaft 2 on the intake side
A timing pulley assy 23 and a step motor 24, which constitute a variable valve timing device, are provided at the tip of the valve 1. On the other hand, the camshaft 22 on the exhaust side
Only a timing pulley 25 is provided at the tip. These timing pulley assy 23 and timing pulley 25 are drivingly connected to the crankshaft via a timing belt (not shown).

Therefore, when the engine 1 is operating, power is transmitted from the crankshaft to the timing pulley assy 23 and the timing pulley 25 through the timing belt, thereby rotating the camshafts 21 and 22, thereby causing the cams 21a to rotate. , 22a are rotated. Also, each valve lifter 19, 20 moves the valve spring 1 according to the profile of each rotated cam 21a, 22a.
By being pressed against the biasing forces of 7 and 18, the intake valve 9 and the exhaust valve 10 move downward, opening the intake port 7a and the exhaust port 8a, respectively. As is well known, the basic opening/closing timing of the intake valve 9 and the exhaust valve 10 depends on the rotation of the crankshaft (two revolutions), that is, the four strokes of the piston 3 (intake stroke, compression stroke,
It is set in advance relative to the vertical movement accompanying the expansion stroke and exhaust stroke. Here, when the intake port 7a is opened due to the downward movement of the piston 3 during the intake stroke, that is, when the intake valve 9
When the combustion chamber 6 is opened, air-fuel mixture is sucked into the combustion chamber 6. Furthermore, when the exhaust port 8a is opened by the upward movement of the piston 3 during the exhaust stroke, that is, when the exhaust valve 10 is opened, burned gas is discharged from the combustion chamber 6 to the exhaust passage 8.

The timing pulley assy 23 on the intake side is driven and controlled in order to change the basic opening/closing timing of the intake valve 9 according to the operating conditions at the time, and the timing pulley assy 23 on the intake side The rotational phase of 21a is changed as appropriate. That is, the timing pulley assy 23 on the intake side is driven and controlled to change the intake timing of the air-fuel mixture into the combustion chamber 6.

In order to ignite the air-fuel mixture introduced into the combustion chamber 6, a spark plug 2 is installed in the cylinder head 5 at the center of the cylinder.
6 is fixed, and its discharge portion 26a is disposed within the combustion chamber 6. This spark plug 26 is connected to the distributor 2
It is driven based on the ignition signal distributed at 7. The distributor 27 synchronizes the high voltage output from the igniter 28 with the crank angle of the engine 1 to the spark plug 2.
It is for distributing to 6 people. Further, the distributor 27 is provided with a rotor 27a that rotates in conjunction with the rotation of the engine 1, and is provided with a rotation speed sensor 29 that detects the engine rotation speed NE from the rotation of the rotor 27a.

Next, the configuration of the variable valve timing device described above will be explained in detail with reference to FIG. An intake-side camshaft 21 that drives the intake valve 9 is rotatably supported by the cylinder head 5 through its cam journal 21b. A timing pulley assy 23 is provided at the tip of the camshaft 21. The timing pulley assembly 23 is composed of a pulley body 32 having a plurality of external teeth 31 on the outer periphery, an inner cap 33 and a cylindrical gear 34 assembled to the pulley body 32.

That is, the pulley main body 32 has a boss 32a and a circumferential wall 32b near its center, and a circumferential groove 32c is formed between the boss 32a and the circumferential wall 32b. Helical teeth 32d are formed on the inner periphery of the circumferential wall 32b. The pulley main body 32 is mounted on the camshaft 21 at its boss 32a so as to be relatively rotatable. On the other hand, the inner cap 33 includes a large cylindrical portion 33a and a small cylindrical portion 33b extending to the opposite side thereof, and helical teeth 33c are formed on the outer periphery of the large cylindrical portion 33a. The inner cap 33 is fitted so that its large cylindrical portion 33a covers the boss 32a, and is assembled to the pulley body 32 so as to be relatively rotatable. Further, the inner cap 33 is fixed to the tip of the camshaft 21 by a bolt 35 and a knock pin 36 so as to be able to rotate integrally therewith. Further, the cylindrical gear 34 is connected to the outer peripheral wall 3
4a and an inner circumferential wall 34b, and a hole 3 is formed in the bottom wall of the inner peripheral wall 34b.
4c is formed. Helical teeth 34d and 34e are formed on the inner and outer peripheries of the inner peripheral wall 34b, respectively, and the outer peripheral wall 34
A circumferential groove 34f is formed between a and the inner peripheral wall 34b. Then, the inner circumferential wall 34b and the circumferential groove 3 of the cylindrical gear 34
4f is the circumferential wall 32b and circumferential groove 32 of the pulley main body 32
It is assembled in an uneven relationship with c.

In this assembled state, the helical teeth 32d, 33c, 34d, and 34e are meshed with each other, and due to the meshing relationship, the cylindrical gear 34 can rotate relative to the camshaft 21 by moving in the axial direction. There is. Further, the timing pulley assy 23 is drivingly connected to the crankshaft via a timing belt (not shown) that is hung around the external teeth 31 of the pulley main body 32.

Therefore, by transmitting the drive from the crankshaft to the timing pulley assy 23, the pulley main body 32 and the inner cap 33, which are connected by the cylindrical gear 34, are rotated together, and further, by the bolt 35 and the knock pin 36, the pulley body 32 and the inner cap 33 are rotated together. The camshaft 21 connected to the inner cap 33 is integrally driven to rotate. The step motor 24 mentioned above is attached to the engine 1 by a bracket (not shown). The step motor 24 has a cylindrical gear 34
A worm gear 37 having a cylindrical shape and having teeth 37a on its outer periphery is attached to its output shaft. This worm gear 37 is fitted to the small cylinder portion 33b of the inner cap 33 so as to be relatively rotatable, and is disposed so as to pass through the hole 34c of the cylindrical gear 34. On the other hand, around the hole 34c of the cylindrical gear 34,
A ring gear 38 having teeth 38a on its inner periphery is assembled by a ball bearing 39 so as to be relatively rotatable. The ring gear 38 is meshed with the outer periphery of the worm gear 37, and due to the meshing relationship, it is movable in the axial direction by rotation.

Therefore, when the timing pulley assy 23 and the camshaft 21 are being rotated together, the step motor 24 is driven and the worm gear 37 is rotated by a predetermined amount, so that the ring gear 38 is rotated on the worm gear 37. while moving in the axial direction. Along with this, the cylindrical gear 34 is moved in the same axial direction, and the pulley main body 3
Relative rotation occurs between the camshaft 2 and the camshaft 21, and the camshaft 21 is twisted. As described above, in the variable valve timing device of this embodiment, the position of the cylindrical gear 34 in the axial direction is changed by driving and controlling the step motor 24, and as a result, the camshaft 21 is twisted. . And camshaft 21
By twisting the intake valve 9, the opening/closing timing of the intake valve 9 is changed from the basic opening/closing timing.

Note that there is an oil passage 40 inside the camshaft 21.
, 41 are formed, and lubricating oil is supplied into the timing pulley assy 23 through the oil passages 40 and 41. As shown in FIG. 1, the aforementioned throttle sensor 14, intake pressure sensor 16, rotation speed sensor 29, etc. are electrically connected to the input side of an electronic control unit (ECU) 42. Further, the above-mentioned injector 11, igniter 28, step motor 24, etc. are electrically connected to the output side of the ECU 42. This E
The CU42 includes a central processing unit (CPU), a read-only memory (ROM), and a readable and rewritable memory (R
AM), etc., is configured as a logic operation circuit.

[0021] In such an electrical configuration, the ECU 4
2 reads the detection values of the respective sensors 14, 16, and 29, and suitably controls the step motor 24 to control the opening/closing timing of the intake valve 9 according to the operating state of the engine 1. In particular, when the engine 1 is accelerated by pressing the accelerator pedal 12, the step motor 24 is driven and controlled to advance the closing timing of the intake valve 9. Also, E
The CU 42 appropriately drives and controls the injector 11 in order to control fuel injection into the intake passage 7 according to the operating state of the engine 1. Similarly, the ECU 42 suitably controls the igniter 28 in order to control the ignition timing by the spark plug 26 according to the operating state of the engine 1.

Next, a method of controlling the engine 1 with the variable valve timing device configured as described above will be explained. In this embodiment, the variable valve timing device is drive-controlled in order to advance the closing timing of the intake valve 9 when the engine 1 accelerates.
The closing timing control of the intake valve 9 executed by the CU 42 will be explained. FIG. 3 is a flowchart illustrating a timing angle calculation routine for controlling the closing timing, which is executed by a regular interrupt at every predetermined time.

When the process shifts to this routine, first, in step 101, the throttle opening degree TA is read based on the detected value of the throttle sensor 14. Also, step 1
At step 02, the engine rotation speed NE is read based on the detected value of the rotation speed sensor 29. Subsequently, in step 103, a timing angle θCAM related to the intake valve 9 is determined from the throttle opening degree TA and the engine speed NE that have been previously read. This timing angle θCAM
As shown in FIG. 4, is determined by referring to a predetermined map using engine speed NE and throttle opening TA as parameters.

Furthermore, in step 104, the difference between the timing angle θCAM found in the current control cycle and the timing angle θCAM0 found in the previous control cycle is found as an angular deviation ΔθCAM. This angular deviation ΔθCAM corresponds to the mechanical operation delay time of the variable valve timing device that occurs between the previous control cycle and the current control cycle.

Then, in step 105, it is determined whether the angular deviation ΔθCAM is greater than or equal to a predetermined value. In other words, it is determined whether the delay in operation of the variable valve timing device is excessive. Here, the angular deviation ΔθCAM
is greater than a predetermined value, that is, if the delay in the operation of the variable valve timing device is excessive, in step 106, a fuel increase value g is determined according to the magnitude of the angular deviation ΔθCAM, and this value is used as the angular deviation correction coefficient. FCAM (F
CAM > 1.0). As shown in FIG. 5, the fuel increase value g is determined by referring to a predetermined map using the angular deviation ΔθCAM as a parameter. This fuel increase value g is a value determined to correct the mechanical operation delay of the variable valve timing device itself described above by increasing the amount of fuel supplied to the combustion chamber 6.

Thereafter, in step 107, the timing angle θCAM in the current control cycle is set as the timing angle θCAM0 in the previous control cycle, and the subsequent processing is temporarily terminated. On the other hand, in step 105, if the angular deviation ΔθCAM is smaller than the predetermined value,
That is, if the delay in the operation of the variable valve timing device is not excessive, the angular deviation correction coefficient F is determined in step 108.
Uniformly set CAM to "1.0".

Thereafter, in step 107, the current timing angle θCAM is changed to the previous timing angle θC.
It is set as AM0, and the subsequent processing is temporarily terminated. Then, the ECU 42 calculates the timing angle θCAM obtained by the above-mentioned timing angle calculation routine to the intake valve 9.
As the target closing timing, the timing angle θC
The step motor 24 is driven and controlled in accordance with AM to advance the closing timing of the intake valve 9.

Next, the fuel injection amount control executed by the ECU 42 together with the above-mentioned closing timing control of the intake valve 9 will be explained. FIG. 6 is a flowchart illustrating a fuel injection amount calculation routine for fuel injection amount control, which is executed by a regular interrupt at every predetermined time. When the process moves to this routine, first in step 201,
Based on the detected value of the rotation speed sensor 29, the engine rotation speed NE
Load. Further, in step 202, the intake pressure PM is read based on the detected value of the intake pressure sensor 16.

Subsequently, in step 203, a basic injection time TP is calculated from the engine speed NE and intake pressure PM read previously. This basic injection time TP is
It is determined by referring to a predetermined map (not shown) using the engine speed NE and intake pressure PM as parameters. Next, in step 204, the air-fuel ratio correction coefficient F
Load AF. This air-fuel ratio correction coefficient FAF is determined by a separate calculation routine, and its explanation will be omitted here.

Furthermore, in step 205, the angular deviation correction coefficient FCAM obtained in the timing angle calculation routine described above is read. Finally, in step 206, the previously calculated basic injection time TP is multiplied by the air-fuel ratio correction coefficient FAF and the angular deviation correction coefficient FCAM, and set as the fuel injection amount TAU in the current control cycle. Terminate the process once.

When the injection timing arrives, the ECU 42 drives and controls the injector 11 in accordance with the fuel injection amount TAU determined as described above, and supplies fuel to the combustion chamber 6. As described above, in the method for controlling an engine with a variable valve timing device according to this embodiment, the variable valve timing device is drive-controlled so as to advance the closing timing of the intake valve 9 when the engine 1 is accelerated. Moreover, at the same time, the fuel injection amount TAU is determined to be further increased than the amount set by various parameters related to the operating state, and the injector 11 is drive-controlled based on the fuel injection amount TAU, and the fuel is injected into the combustion chamber 6.
supplied to That is, if there is a mechanical delay in the variable valve timing device, that is, the angular deviation ΔθCAM
is greater than a predetermined value, the basic injection time TP determined by the engine speed NE and the intake pressure PM is calculated using the well-known air-fuel ratio correction coefficient FAF and the mechanical operation delay compensation of the variable valve timing device. is multiplied by the newly added angular deviation correction coefficient FCAM to obtain the fuel injection amount TA.
U is determined, and the injector 11 is driven and controlled based on the fuel injection amount TAU. Therefore, the output of the engine 1 is quickly and smoothly increased by the increase in the fuel injection amount TAU due to the angular deviation correction coefficient FCAM.

Therefore, when the engine 1 accelerates, the mechanical operation delay that remains unavoidably in the variable valve timing device is compensated for by the rapid and smooth increase in output of the engine 1, and the closing timing control of the intake valve 9 is compensated for. Response delays can be eliminated. As a result, the rise of the intake air amount in the engine 1 can be improved, thereby improving the acceleration feeling.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and may be practiced by changing a part of the structure as appropriate without departing from the spirit of the invention. For example, in the above embodiment, the gasoline engine 1 is used, but it can also be applied to a diesel engine.

[0034]

[Effects of the Invention] As detailed above, according to the present invention,
When the engine accelerates, the variable valve timing device is controlled to advance the closing timing of the intake valve, and
Since the fuel supply means is controlled to increase the fuel supply amount further than the amount of fuel supplied according to various parameters of the operating state, the output of the engine is quickly and smoothly increased during acceleration, and the variable valve timing device It is possible to properly compensate for mechanical operation delays that cannot be compensated for by itself, and thereby exhibits the excellent effect of eliminating response delays in valve timing control.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram illustrating a gasoline engine in an embodiment embodying the present invention.

FIG. 2 is a sectional view showing the configuration of a variable valve timing device in one embodiment.

FIG. 3 is a flowchart illustrating a timing angle calculation routine for intake valve closing timing control in one embodiment.

FIG. 4 is a diagram showing a map in which the timing angle of the intake valve is predetermined using engine speed and throttle opening as parameters in one embodiment.

FIG. 5 is a diagram showing a map in which a fuel increase value is predetermined using an angular deviation as a parameter in one embodiment.

FIG. 6 is a flowchart illustrating a fuel injection amount calculation routine for fuel injection amount control in one embodiment.

[Explanation of symbols]

1... Engine 6... Combustion chamber 7... Intake passage 9... Intake valve 11... Injector 23 as a fuel supply means... Timing pulley assy 24 forming a variable valve timing device... Step motor 42 forming a variable valve timing device... ECU

Claims (1)

[Claims] 1. An intake valve that opens and closes an intake passage leading to a combustion chamber of an engine, a fuel supply means that supplies fuel to the combustion chamber, and a variable valve timing device that varies the opening and closing timing of the intake valve. , in a method for controlling an engine with a variable valve timing device, wherein the variable valve timing device is controlled to advance the closing timing of the intake valve when the engine is accelerating; A method for controlling an engine with a variable valve timing device, characterized in that the fuel supply means is controlled so that the amount of fuel supplied is further increased than a set amount of fuel supplied.