JP3161119B2 - Valve timing control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve timing control apparatus provided with a variable valve timing mechanism for continuously changing the opening / closing timing of an intake valve or an exhaust valve in accordance with the operation state of an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, as disclosed in JP-A-59-120707, output control of an internal combustion engine has been described.
The valve overlap is controlled in accordance with operating conditions such as the amount of intake air of the internal combustion engine, engine speed, temperature, etc., i.e., low load, high load, etc. to improve idle stability, reduce emissions, improve fuel efficiency, etc. Achieved in a well-balanced manner.

[0003]

However, in the case where the valve timing is continuously changed based on the intake air amount and the engine speed, the operation of the air conditioner, the shift position of the AT, or the electric control is performed even at the same idling time. There has been a problem that the valve timing changes due to a dynamic load or the like, the idle characteristics deteriorate, and engine stall occurs.

[0004] It is an object of the present invention to continuously control the valve timing based on the engine speed and intake air amount of an internal combustion engine. When the throttle is fully closed, the vehicle speed and the idle speed when the engine speed is lower than a predetermined value are set. It is an object of the present invention to provide a valve timing control device for an internal combustion engine capable of improving characteristics and improving controllability of an idle speed.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a variable valve timing for continuously varying at least one of an intake valve and an exhaust valve of an internal combustion engine mounted on a vehicle. Mechanism, calculating means for calculating a drive target value of the variable valve timing mechanism based on the number of revolutions and load of the engine, and driving force control for controlling the driving force of the variable valve timing mechanism based on the drive target value Means for controlling the valve timing of an internal combustion engine, wherein the vehicle includes an air conditioner serving as a load on the engine and an on / off switch for turning on and off the operation of the air conditioner. The drive target value of the variable valve timing mechanism is differently fixed depending on whether the on / off switch is on or off. It is an gist to set the value.

[0006]

According to the above arrangement, the engine is brought into an idle state.
Here, the drive target value of the variable valve timing mechanism is
More appropriate fixed value depending on the presence or absence of air conditioner load
Are selected and based on the selected fixed drive target values
The drive of the variable valve timing mechanism is now controlled.
You. For this reason, rotation fluctuation and vibration are suppressed and more stable
The obtained idle characteristics can be obtained.

[0007]

[0008]

EXAMPLES Hereinafter, a description will be given of an embodiment embodying the valve timing system for an internal combustion engine in the present invention according to FIGS. 1 to 7.

FIG. 1 is a schematic structural view (only one cylinder is shown) illustrating a gasoline engine 1 as an internal combustion engine mounted on a vehicle according to this embodiment. A piston 3 is provided in a cylinder bore 2a formed in a cylinder block 2 of the engine 1 so as to be vertically movable. The piston 3 is connected to a crankshaft (not shown) via a rod 4. A space surrounded by the piston 3, the cylinder bore 2a, and the cylinder head 5 covering the upper side of the bore 2a is a combustion chamber 6.

In the combustion chamber 6, an intake passage 7 and an exhaust passage 8 are provided in communication with each other. An opening / closing intake valve 9 is attached to an intake port 7a opening to the combustion chamber 6 of the intake passage 7. Further, an exhaust valve 10 for opening and closing is mounted on an exhaust port 8a opening to the combustion chamber 6 of the exhaust passage 8.

Outside air is introduced into the intake passage 7 through an air cleaner (not shown). An injector 1 for fuel injection is provided near the intake port 7a in the intake passage 7.
1 is provided 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.
A mixture of fuel and outside air injected from the injector 11 and taken into the intake passage 7 is supplied to the intake valve 9.
Is opened to the combustion chamber 6 through the intake port 7a. Further, the air-fuel mixture introduced into the combustion chamber 6 explodes and burns, so that the driving force of the engine 1 is obtained via the piston 3 and the crankshaft. Further, the burned gas burned in the combustion chamber 6 is discharged from the exhaust port 8a to the outside through the exhaust passage 8 when the exhaust valve 10 is opened.

In the middle of the intake passage 7, the accelerator pedal 1
2 is provided with a throttle valve 13 which is opened and closed in conjunction with the operation of Step 2. When the throttle valve 13 is opened and closed, the amount of air taken into the intake passage 7 is adjusted.

In the vicinity of the throttle valve 13, a throttle sensor 14 for detecting the throttle opening TA is provided.
"ON" when the throttle valve 13 is in the fully closed position
Fully-closed switches 14a that output the fully-closed signals LL are provided. Further, a surge tank 15 for smoothing the pulsation of the intake air amount is provided downstream of the throttle valve 13. Furthermore, upstream of the throttle valve 13, well-known e Africa for detecting an amount of intake air taken into the intake passage 7 from the external Rometa 1
6 are provided.

Next, a valve operating mechanism for the intake valve 9 and the exhaust valve 10 will be described. An intake valve 9 and an exhaust valve 10 are stems 9a, 10 extending upward, respectively.
The valve springs 17 and 18 and the valve lifters 19 and 20 are mounted on the upper portions of the stems 9a and 10a, respectively. Cams 21a and 22a are provided on the respective valve lifters 19 and 20 so as to engage with each other. The cams 21a and 22a are formed on the intake-side camshaft 21 and the exhaust-side camshaft 22 supported by the cylinder 5 by the number of all cylinders. Then, the intake valve 9 and the exhaust valve 10 are moved upward by the urging force of the valve springs 17 and 18.
Further, it is urged in a direction to close the intake port 7a and the exhaust port 8a. In this biased state, each stem 9a, 1
The upper end of Oa is always in contact with cams 21a and 22a via valve lifters 19 and 20.

In this embodiment, in order to make only the opening / closing timing of the intake valve 9 variable, a camshaft 21 on the intake side is provided.
A variable valve timing mechanism (hereinafter simply referred to as “V
A VT 23 is provided with a timing pulley assembly 24 and a step motor 25. The step motor 25 includes a plurality of electromagnetic coils, and sequentially selects an electromagnetic coil to be excited among them, so as to rotate in a predetermined direction at each step. On the other hand, only the timing pulley 26 is provided at the tip of the camshaft 22 on the exhaust side. These timing pulley rear Sshii 24 and the timing pulley 26 is drivingly connected to the crankshaft via a timing belt, not shown.

Therefore, when the engine 1 is operated, power is transmitted from the crankshaft to the timing pulley assembly 24 and the timing pulley 26 via the timing belt, whereby the respective camshafts 21 and 22 are driven to rotate, and the respective camshafts are respectively driven. 21a and 22a are respectively rotated. Further, the valve lifters 19 and 20 are pressed against the urging forces of the valve springs 17 and 18 according to the profile of each of the cams 21a and 22a to be rotated.
Intake valve 9 and exhaust valve 10 is an intake port 7a and the exhaust port 8 a is opened each move downward. The basic opening / closing timing of the intake valve 9 and the exhaust valve 10 accompanies four strokes (the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke) of the piston 3 performed during two rotations of the crankshaft, as is well known. It is set in advance relative to the vertical movement. Here, when the intake port 7 a is opened by the downward movement of the piston 3 during the intake stroke, that is, when the intake valve 9 is opened, the air-fuel mixture is sucked into the combustion chamber 6. Further, when the exhaust port 8a is opened due to the upward movement of the piston 3 during the exhaust stroke, that is, when the exhaust valve 10 is opened, the burned gas is discharged from the combustion chamber 6 to the exhaust passage 8.

The VVT 23 on the intake side is driven and controlled to change the basic opening / closing timing of the intake valve 9 according to the operating state at each time.
1. The rotating phase of each cam 21a is appropriately changed. That is, the drive of the VVT 23 on the intake side is controlled so as to change the intake timing of the air-fuel mixture into the combustion chamber 6. Then, by changing the basic opening / closing timing of the intake valve 9, the valve overlap between the intake valve 9 and the exhaust valve 10 is changed.

In order to ignite the air-fuel mixture introduced into the combustion chamber 6, an ignition plug 2 is mounted on a cylinder head 5 at the center of the cylinder.
7 is fixed, and a discharge portion 27 a thereof is arranged in the combustion chamber 6. This spark plug 27 is connected to the distributor 2
It is driven based on the ignition signal distributed at 8. The distributor 28 distributes the high voltage output from the igniter to the ignition plug 27 in synchronization with the crank angle of the engine 1. The distributor 28 is provided with a rotor that is rotated in conjunction with the rotation of the engine 1.
Is provided. Further, the distributor 28 is provided with a cylinder discrimination sensor 31 that detects a crank angle reference position of the engine 1 at a predetermined ratio in accordance with the rotation of the rotor 28a and outputs a reference signal G thereof.

The throttle sensor 14 described above, the fully closed switch 14a as the throttle opening state detecting means, e A
Off Rometa 16, speed sensor 30 as a rotation speed detecting means, the starter switch 39 and a cylinder-discriminating sensor 31
Constitutes operating state detecting means for detecting the operating state of the engine 1. In addition, a water temperature sensor 32 for detecting the temperature (cooling temperature) THW of the cooling water of the engine 1 is provided on the cylinder block 2 as the operating state detecting means. Is installed. The water temperature sensor 32 also serves as a temperature detecting means for detecting the temperature of the engine 1. In the middle of the exhaust passage 8, an oxygen sensor 33 for detecting the oxygen concentration in the exhaust gas is mounted. Further, in this embodiment, a vehicle speed sensor 34 is provided as vehicle speed detecting means for detecting the running speed (vehicle speed) SP of the vehicle. The vehicle speed sensor 34 is attached to a transmission (not shown) and is driven by rotation of a gear. In addition, in this embodiment, a brake pedal 35 operated for vehicle braking is provided.
Is provided, a brake sensor 36 is provided which is turned "ON" upon detection of the operation and outputs a brake signal BS.

The brake pedal 35 is provided with a brake booster 37 connected thereto. The brake booster 37 has a one-way valve 37a, and is communicated from the valve 37a to the intake passage 7 downstream of the throttle valve 13 through a communication pipe 37b. As is well known, the brake booster 37 is a braking force doubling device using the negative pressure of the intake passage 7, and the description of the structure is omitted here.

In this embodiment, the engine 1 is provided with a starter 38 for applying a rotational force by cranking when the engine 1 is started. Also, this starter 3
8 is provided with a starter switch 39 for detecting the on / off operation. As is well known, the starter 38
Is turned on / off by operation of an ignition switch (not shown). While the ignition switch is being operated, the starter 38 is turned on, and the starter signal ST is output from the starter switch 39. ing.

As shown in FIG. 1 , the throttle sensor 14, the fully closed switch 14a, the air flow meter 16, the rotation speed sensor 30, the cylinder discrimination sensor 31, the water temperature sensor 32, the oxygen sensor 33, the vehicle speed sensor 34, and the starter The switch 39 and the like are electrically connected to an input side of an engine electronic control unit (hereinafter simply referred to as “engine ECU”) 40. The injector 11 and the igniter 29 described above are electrically connected to the output side of the engine ECU 40. And the engine ECU 4
0, based on an output signal from the fully closed switch 14a, et Africa Rometa 16, each sensor 14,30～34 and starter switch 39, the injector 11 and igniter 2
9 and the like are suitably controlled.

The engine ECU40 is mainly fuel amount control device and Nikki by controller Tsukasa the ignition timing control of the engine 1, in addition to this, as in this embodiment shown in FIG. 1,
A VVT ECU 41 that constitutes a drive control unit for controlling the drive of the VVT 23 is provided. This VVT ECU
Reference numeral 41 controls the rotation direction and the rotation amount of the output shaft of the step motor 25. Therefore, VVT
To the input side of the ECU 41, the throttle opening TA, the fully closed signal LL, the engine speed NE, the cooling water temperature THW, the vehicle speed SP, the starter signal ST, the detected value of the intake air amount Ga, and the like are input from the engine ECU 40 as data signals. You.
Also, the brake sensor 3 is provided on the input side of the VVT ECU 41.
6 is input. Furthermore, VV
TECU41 is to reduce the pumping loss of the engine 1
To control the opening and closing timing of the intake valve 9 as that,
Engine 1 based on input data signal etc.
The magnitude of the valve overlap according to the operating state of the motor is determined, and a valve timing control signal for suitably controlling the step motor 25 is output from the output side.

Next, the engine ECU 40 and the VVTE
The configuration of CU41, be described with reference to the block diagram of FIG. 2, 3. FIG. 2 is a block diagram illustrating an electrical configuration of the engine ECU 40. The engine ECU 40 includes a central processing unit (CPU) 42, a read-only memory (ROM) 43 in which a predetermined control program and the like are stored in advance, a CP
A theory in which a random access memory (RAM) 44 for temporarily storing the operation result of U42, a backup RAM 45 for storing previously stored data, and the like, and each of these units and an external input circuit 46 and an external output circuit 47 are connected by a bus 48 It is configured as an arithmetic circuit.

The external input circuit 46 includes the throttle sensor 14, the fully closed switch 14a, the air flow meter 1
6, a rotation speed sensor 30, a cylinder discrimination sensor 31, a water temperature sensor 32, an oxygen sensor 33, a vehicle speed sensor 34, and a starter switch 39 are connected to each other. On the other hand, the injector 11, the igniter 29, and the VVT ECU 41 are connected to the external output circuit 47, respectively.

The CPU 42 reads, as input values, signals from the fully-closed switch 14a, the air flow meter 16, the sensors 14, 30 to 34, the starter switch 39, and the like, which are input via the external input circuit 46. When reading the input value, the external input circuit 46 controls the throttle sensor 14, the air flow meter 16, the water temperature sensor 3
2 and the input values from the oxygen sensor 3 are subjected to analog / digital conversion processing. External input circuit 4
In 6, the input values from the rotation speed sensor 30, the cylinder discrimination sensor 31, the vehicle speed sensor 34 and the like are subjected to waveform shaping processing. Then, the CPU 42 operates the fully closed switch 14.
a, air flow meter 16, each sensor 14, 30 to 34
The injector 11 and the igniter 29 are suitably controlled based on the input values read from the starter switch 39 and the like.

In addition, the CPU 42 of the signals read as input values from the fully closed switch 14a, the air flow meter 16, the sensors 14, 30 to 34, the starter switch 39, and the like via the external input circuit 46, the throttle opening degree T
A, fully closed signal LL, engine speed NE, cooling water temperature TH
W, vehicle speed SP, starter signal ST, intake air amount Ga, and the like are output as data signals through external output circuit 17 as VVTE.
Output to CU41.

FIG. 3 is a block diagram illustrating an electrical configuration of the VVT ECU 41. The VVT ECU 41 includes a micro processing unit (MPU) 50 and a VVT 2
R in which a predetermined control program for 3 etc. is stored in advance.
RA for temporarily storing the operation results of the OM 51 and the MPU 50
M52 and the like, and these units and the input / output port 53 and the output port 54 and the like are connected as a theoretical operation circuit by a bus 55. The VVT ECU 41 is a clock generator 5 for generating a periodic clock pulse.
6, and a clock pulse is supplied from the generator 56 to the MPU 50. Furthermore, VV
The TECU 41 includes a latch circuit 57 and a gate 58 connected to the output port 54.

The input / output port 53 is connected to the engine ECU 40. The brake sensor 36 is connected to the input / output port 53, and the gate 58 is connected to the step motor 2.
5 is connected.

The MPU 50 receives the throttle opening TA and the fully closed signal LL input through the input / output port 53,
Signals such as the engine speed NE, cooling water temperature THW, vehicle speed SP, starter signal ST, intake air amount GE, and brake signal BS are read as input values, and the step motor 25 is suitably controlled based on the read input values. That is, the MPU 50 reads the ROM 51 based on the read input value.
Step motor 2 according to the control program stored in
The rotation direction and the number of steps of 5 are calculated and determined, and the calculation result is output to the latch circuit 57 through the output port 54 as a valve timing control signal. Latch circuit 5
7 receives the valve timing control signal and outputs an opening / closing command of the gate signal 58 in accordance with a predetermined sequence to execute the signal. Then, the gate 58 selects an electromagnetic coil to be excited and drives the step motor 25 according to the opening / closing command.

Next, the structure of the VVT 23 will be described.
4 will be described. The intake side camshaft 21 for driving the intake valve 9 is rotatably supported by the cylinder head 5 by its cam journal 21b. And
At the tip of the camshaft 21, a timing pulley assembly 24 and a step motor 25 constituting the VVT 23 are provided. The timing pulley assembly 24 includes a pulley main body 62 having a plurality of external teeth 61 on the outer periphery, an inner cap 63 and a cylindrical gear 64 attached to the pulley main body 62.

That is, the pulley body 62 has a boss 62a and a circumferential wall 62b near the center thereof.
A circumferential groove 62c is formed between a and the circumferential wall 62b.
Helical teeth 62d are formed on the inner periphery of the circumferential wall 62b. The pulley body 62 is mounted on the camshaft 21 at its boss 62a so as to be relatively rotatable.
On the other hand, the inner cap 63 includes a large cylindrical portion 63a and a small cylindrical portion 63b extending to the opposite side, and helical teeth 63c are formed on the outer periphery of the large cylindrical portion 63a. The inner cap 63 is fitted so that the large cylindrical portion a covers the boss 62a, and is attached to the pulley main body 62 so as to be relatively rotatable. Further, the inner cap 63 is fixed to the tip of the camshaft 21 so as to be integrally rotatable by a bolt 65 and a knock pin 66. Further, the cylindrical gear 64 has an outer peripheral wall 64.
a and an inner peripheral wall 64b.
c is formed. Helical teeth 64d and 64e are formed on the inner and outer circumferences of the inner peripheral wall 64b, respectively.
A circumferential groove 64f is formed between the inner peripheral wall 64b and the inner peripheral wall 64b. Then, the inner peripheral wall 64b and the circumferential groove 64 of the cylindrical gear 64 are formed.
f is a circumferential wall 62b and a circumferential groove 62c of the pulley body 62.
Are mounted in a concave and convex relationship.

In this assembled state, each helical tooth 6
2d, 63c, 64d, and 64e are meshed with each other, and the cylindrical gear 64 is relatively rotatable with the camshaft 21 by moving in the axial direction due to the meshing relationship. The timing pulley assembly 24 is drivingly connected to the crankshaft via a timing belt (not shown) mounted on the external teeth 61 of the pulley body 62.

Therefore, the driving force is transmitted from the crankshaft to the timing pulley assembly 24, so that the pulley main body 62 and the inner cap 6 connected by the cylindrical gear 64 are connected.
3 are integrally rotated, and the camshaft 21 connected to the inner cap 63 by the bolt 65 and the knock pin 66 is integrally rotated.

The step motor 25 is attached to the engine 1 by a bracket (not shown). The step motor 25 is for moving the cylindrical gear 64 in the axial direction. A worm gear 67 having a cylindrical shape and having teeth 67a on the outer periphery is attached to an output shaft thereof.
The worm gear 67 is a small cylindrical portion 63b of the inner cap 63.
And the cylindrical gear 6
Four holes 64c are disposed through the holes 64c. On the other hand, around the hole 64c of the cylindrical gear 64, a ring gear 68 having teeth 68a on its inner periphery is mounted by a ball bearing 69 so as to be relatively rotatable. And the ring gear 6
8 is meshed on the outer periphery of the worm gear 67, and is rotatable in the axial direction by rotation of the worm gear 67 due to the meshing relationship. In order to prevent the rotation of the ring gear 68, a long groove 68 extending in the axial direction is provided on the outer periphery of the ring gear 68 on the side of the step motor 58.
b is formed. In addition, a detent member 70 which is formed in a tubular shape and extends toward the timing pulley assembly 24 is attached to a casing of the step motor 25. The long groove 68b is provided on the inner periphery of the rotation preventing member 70.
From the engagement between the projection 70a and the long groove 68b
The ring gear 68 is prevented from rotating, and is allowed to move only in the axial direction.

Therefore, when the timing pulley assembly 24 and the camshaft 21 are integrally rotated, the step motor 25 is driven to rotate the worm gear 67 by a predetermined amount in a certain direction, so that the ring gear 68 is rotated.
Is moved in the axial direction while being prevented from rotating on the worm gear 67. Along with this, the cylindrical gear 64 is moved in the same axial direction, and a relative rotation occurs between the pulley main body 62 and the camshaft 21 to impart a twist to the camshaft 21.
Thus, in the VVT 23 of this embodiment, the position of the cylindrical gear 64 in the axial direction is changed by controlling the driving of the stepping motor 25, and as a result, the camshaft 21 is twisted. And the camshaft 2
By imparting the twist to 1, the opening / closing timing of the intake valve 9 is changed, and the valve overlap is changed.

The oil passage 7 is provided inside the camshaft 21.
The lubricating oil is supplied to the inside of the timing pulley assembly 24 through the oil passages 71 and 72.

[0038] Now, FIG. 5及 Beauty view the operation of the valve timing control apparatus for internal combustion engine formed as above 6
It will be described according to. Figure 5 VVT that及 beauty 6 is executed by VVTECU41 for controlling the operations of the VVT23
It is a flowchart of a control routine, which is executed by a periodic interruption every predetermined time.

In this routine, first, in step 101, the throttle opening degree TA, the fully closed signal LL, the engine, and the throttle sensor 14, the fully closed switch 14a, the rotation speed sensor 30, the water temperature sensor 32, the vehicle speed sensor 34 and the starter switch 39 are detected. The rotational speed NE, the cooling water temperature THW, the starter signal ST, the intake air amount Ga, and the vehicle speed SP are read from the engine ECU 40, respectively. Further, a brake signal BS detected by the brake sensor 36 is read.

Subsequently, in step 102, it is determined whether or not the starter signal ST is "ON", that is, whether or not the engine 1 is being started. If the starter signal ST is "ON", it is determined that the engine is being started, and in step 105, the number of steps V for controlling the step motor 25 corresponding to the target advance value (fixed value) after the start is determined.
STA is set as the target step number Vst. If the starter signal ST is not "ON" in step 102, it is determined that the start of the engine 1 has been completed. In step 103, it is determined whether or not the fully closed signal LL is "ON". It is determined whether or not there is.

If the fully closed signal LL is "ON", it is determined that the vehicle is decelerating or idling, and the routine proceeds to step 106. In step 106, the vehicle speed becomes "1".
0 km / h ”is determined. If the vehicle speed SP is "10
If it is not more than "km / h", it is determined in step 107 whether or not the engine speed NE exceeds "2000 rpm". Also, at step 106, the vehicle speed SP is "10 km / h".
If it exceeds, the process proceeds to step 104. If the engine speed NE is equal to or less than "2000 rpm" in step 107, the step number Vidle (fixed value) for controlling the step motor 25 corresponding to the target advance value (fixed value) is set in step 108. Set as Vst. In step 107, the engine speed is set to "2000".
rpm ”, the routine proceeds to step 104.

If the fully closed signal LL is not "ON" in step 103, the routine proceeds to step 104 as normal running, which is neither deceleration nor idling. Step 1
In step 04, based on the previously read engine speed NE and intake air amount GE, a calculation result of a function f (NE, Ga) having these values as parameters is used as a target step number for opening / closing timing control of the intake valve 9. After setting as Vst, the process proceeds to step 109. This function f (NE,
The calculation of Ga) is performed with reference to a map stored in the ROM 51 in advance.

In step 109, based on the previously read water temperature THW, a function f (T
After the calculation result of HW) is set as the number of correction steps VTHW for opening / closing timing control of the intake valve 9, the routine proceeds to step 110. The calculation of the function f (THW) is performed with reference to a map stored in the ROM 51 in advance.

In step 110, the target step number Vst after water temperature correction is obtained by subtracting the correction step number VTHW from the target step number Vst set in step 105 or step 108, and the routine proceeds to step 111. In step 111, it is determined whether or not 2 msec has elapsed since the start of the VVT control routine processing.
If not, the process jumps to step 101 and repeats steps 102 to 110. Step 11
If it is determined at 1 that 2 msec has elapsed, the process proceeds to step 112.

In step 112, the result obtained by subtracting the current step number Vpo of the step motor 25 from the set target step number Vst is used as the control step number STEP.
Set as

Next, at step 113, it is determined whether or not the control step number STEP is "0". Here, if the control step number STEP is “0”, the subsequent processing is temporarily terminated without driving the step motor 25. On the other hand, if the control step number STEP is not “0” in step 113,
In 4, it is determined whether or not the control step number STEP is larger than “0”, that is, whether or not the control step number STEP is a positive number. Here, the number of control steps ST
If EP is a positive number, the control flag DIR is reset to "0" in step 115, and
Move to.

If the number of control steps STEP is a negative number in step 114, step 116
Sets the control flag DIR to "1". Next, in step 117, after setting the absolute value of the control step number STEP as a new control step number STEP,
Move to step 118. Then, in a step 118, it is determined whether or not the control flag DIR is "1". When the control flag DIR is “1”, the step motor 25 of the intake side VVT 23 is determined in step 119.
Is reversed by one step, and then the process proceeds to step 121. When the control flag DIR is “0”, the step motor 25 is rotated forward by one step in step 120, and then the process proceeds to step 121.

In step 121, the number of control steps STE
The result obtained by subtracting “1” from P is set as a new control step number STEP. Then, in step 122, the newly set control step number STEP is “0”.
Is determined. If the new control step number is not "0", the process jumps to step 118 and repeats the processing of steps 118 to 122.
That is, the drive control of the intake side VVT 23 is performed.

On the other hand, if the new control step number STEP is "0" in step 126, the subsequent processing is temporarily terminated. Thus, the drive of the VVT 23 is controlled by the control of the step motor 25, and the opening / closing timing of the intake valve 9 is controlled.

As described above, in this embodiment, when the throttle valve 13 is fully closed, if the vehicle speed is equal to or less than "10 km / h" and the engine speed is equal to or less than "2000 rpm",
The target step number Vidle for controlling the step motor 25 corresponding to the target advance value (fixed value) is a fixed value. Therefore, in such an idle state, the valve timing does not change even if the air conditioner is operated, the shift position of the AT shift lever is changed, or the engine speed is increased by other disturbances. The characteristics do not deteriorate.

Therefore, engine stall due to deterioration of idle stability does not occur, and smooth idle characteristics can be obtained. Further, since the valve timing at the time of idling is fixed, the combustion state at the time of idling can be stabilized, thereby improving the fuel efficiency at the time of idling and reducing the amount of harmful exhaust gas. Can be.

Meanwhile, in this embodiment, a shift position switch have shifted even though not shown for detecting whether a located at any shift shift lever for AT, a air conditioner on-off switch mounted on the vehicle On / off switches of other electric loads are connected to the engine ECU 40. And the CPU of the engine ECU 40
Reference numeral 42 denotes a fully closed switch 14a, an air flow meter 16, and sensors 14 and 30 which are input through an external input circuit 46.
To 34, a starter switch 39, a shift position switch, an on / off switch of an air conditioner mounted on the vehicle, and an on / off switch of another electric component, etc., are read as input values. Next, these
Shift switch, air conditioner on / off switch
Signals from the on / off switches of switches and other electrical loads.
An example of the control procedure when reading together as input values
Will be described.

In this case, in step 101 in the above-described flowchart, the throttle sensor 14, the fully-closed switch 14a, the rotational speed sensor 30, the water temperature sensor 3
2. Vehicle speed sensor, starter switch 39, shift position switch, on / off switch of air conditioner mounted on the vehicle, on / off switch of other electric loads, throttle opening degree TA, fully closed signal LL, engine The rotational speed NE, the cooling water temperature THW, the starter signal ST, the intake air amount GE, the vehicle speed SP, the shift position signal, the on / off signal of the air conditioner, and the on / off signal of other electric loads are read from the engine ECU 40, respectively.

Then, steps 120 to 125 as shown in FIG. 7 are provided between steps 107 and 109 in the above-described flowchart .

That is, if the engine speed NE is equal to or less than "2000 rpm" in step 107, it is determined in step 120 whether or not the shift position of the AT shift lever is in "D". When the shift position is “D”, the process proceeds to step 125. In step 125, the number of steps Vidle for controlling the step motor 25 corresponding to the target advance value (fixed value)
1 (fixed value) is set as the target step number Vst, and the process proceeds to step 109.

If it is determined in step 120 that the shift position of the AT shift lever is not at "D", it is determined in step 121 whether or not the shift lever is turned on based on an on / off signal of the air conditioner. If it is on, the process proceeds to step 124. Step 1
At 24, the step number Vidle2 (fixed value) for controlling the step motor 25 corresponding to the target advance angle value (fixed value) is set as the target step number Vst, and the routine proceeds to step 109.

If it is determined in step 121 that the air conditioner is not turned on based on the on / off signal, that is, if the air conditioner is off, the process proceeds to step 122 to determine whether the air conditioner is turned on based on the on / off signal of another electric load. Judge. If it is on, the process proceeds to step 124.

If the on / off signals of the other electric loads are turned off in step 122, step 123
Move to In step 123, the target advance value (fixed value)
Is set as the target step number Vst for the control of the step motor 25 corresponding to the step number 25, and the process proceeds to step 109.

The above-mentioned step numbers Vidle1, Vidle
2 and Vidle 3 are mutually different values, and are the number of steps for controlling the step motor 25 corresponding to the most suitable target advance value (fixed value) in each state.

Therefore, according to the above configuration, it is possible to obtain more suitable opening / closing timing according to the engine operating state. Note that the present invention is not limited to the above-described embodiment, and can be arbitrarily changed without departing from the spirit of the present invention.

(1) In the above-described embodiment, the VVT 23 that changes only the opening / closing timing of the intake valve 9 is provided.
VV that makes only the opening / closing timing of the exhaust valve 10 variable
It is also possible to provide a VVT that makes T and the opening / closing timing of both the intake valve 9 and the exhaust valve 10 variable.

(2) In the above embodiment, the step motor 2
Although the intake-side VVT 23 having a drive limit of 5 is employed, a hydraulically driven VVT may be employed. (3) In the above embodiment, the present invention is embodied in the gasoline engine 1. However, the present invention can be embodied in a diesel engine.

[0063]

As described in detail above, according to the present invention,
Engine speed of the internal combustion engine, when continuously controlling the valve timing based on the intake air amount, the throttle is fully closed, or particular or air conditioners are actuated, the shift position of the shift lever for AT is changed Alternatively, even if the engine speed increases due to other disturbances, the valve timing does not change, and the idle characteristics do not deteriorate. Therefore, engine stall due to deterioration of idle stability does not occur, and not only smooth idle characteristics can be obtained, but also the combustion state at idle can be stabilized, thereby improving fuel efficiency at idle. And an excellent effect that the amount of harmful exhaust gas can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a gasoline engine according to one embodiment of the invention.

FIG. 2 is a block diagram showing an electrical configuration of the engine ECU.

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

FIG. 4 is a sectional view showing a configuration of the VVT.

FIG. 5 is a diagram showing a “VVT” which is also executed by the VVT ECU.
It is a flowchart explaining a "control routine."

FIG. 6 is a flowchart illustrating a “VVT control routine”;

FIG. 7 is a flowchart illustrating a modified routine of the “VVT control routine”.

[Explanation of symbols] 1: engine as internal combustion engine, 6: combustion chamber, 7: intake
Passage, 8 ... Exhaust passage, 9: Intake valve, 10: Exhaust valve
, 23 ... VVT, 14 ... Throttle sensor, 14a ...
Fully closed switch, 30: speed sensor, 34: vehicle speed sensor
, 39 ... Starter switch (14, 14a, 30, 3)
9 constitutes operating state detecting means), 41 ... drive control
VVT ECU constituting the control means.

Continuation of front page (56) References JP-A-59-113221 (JP, A) JP-A-1-117976 (JP, A) JP-A-4-347342 (JP, A) JP-B-63-29102 (JP, A) , B2) Jikgyo 4-13381 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 13/02 F01L 1/34

Claims (1)

(57) [Claims] 1. A variable valve timing mechanism for continuously varying at least one of an intake valve and an exhaust valve of an internal combustion engine mounted on a vehicle, and the variable valve based on a rotation speed and a load of the engine. A valve timing control device for an internal combustion engine, comprising: a calculation unit that calculates a drive target value of a timing mechanism; and a drive force control unit that controls a drive force of the variable valve timing mechanism based on the drive target value. An air conditioner serving as a load on the engine; and an on / off switch for turning on / off the operation of the air conditioner. The arithmetic unit is configured to change the on / off switch between an on state and an off state when the engine is idle. A valve tie for an internal combustion engine, wherein a drive target value of a valve timing mechanism is set to different fixed values. Ring controller.