JP3209141B2 - Variable valve timing control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve timing control device for controlling the opening / closing operation timing of a valve of an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, as this kind of technology, for example, a technology disclosed in Japanese Patent Application Laid-Open No. 5-90007 is known. In this technique, a variable valve timing mechanism for adjusting the opening / closing timing of an intake valve of an engine is mounted. When the deceleration state of the engine is detected, that is, the throttle valve is in the fully closed state,
When the intake pressure is on the negative pressure side than a predetermined value, the variable valve timing mechanism is controlled to control the opening / closing timing of the intake valve on the advance side.

According to this technique, the amount of valve overlap increases, and a high pressure flows from the exhaust side to the intake side, and the pressure in the intake passage increases. Therefore, the so-called "oil rising" in which the engine oil is sucked into the combustion chamber side from between the cylinder and the piston is prevented. As a result, wasteful oil consumption is suppressed.

[0004]

However, in the above-mentioned prior art, the opening / closing timing of the intake valve is uniformly controlled to the advance side by a constant amount regardless of the gear position (shift position) at that time. . Here, in the case of a light load, when the displacement angle is advanced, the amount of overlap increases, so that the degree of vacuum in the cylinder is not ensured, and the pumping loss becomes small. For this reason, when the shift position is a high gear position such as the fourth speed or the fifth speed, there is a possibility that the effect of the engine brake is particularly deteriorated.

The present invention has been made in view of the above-mentioned circumstances, and has as its object to provide a variable valve timing control device capable of suppressing wasteful oil consumption without deteriorating the effectiveness of engine braking. Is to do.

[0006]

In order to achieve the above object, according to the first aspect of the present invention, a variable valve for adjusting the opening / closing timing of at least one of an intake valve and an exhaust valve provided in an internal combustion engine is provided. A valve timing mechanism; deceleration state determination means for determining whether the internal combustion engine is in a deceleration state; and a gear position for detecting a parameter corresponding to a gear ratio between an output shaft of the internal combustion engine and a drive wheel shaft of the vehicle. When the detection means and the deceleration state determination means determine that the internal combustion engine is in a deceleration state, the valve overlap amount is large when the gear position detected by the gear position detection means is smaller than a predetermined position. The variable valve timing mechanism is controlled so that the valve overlap amount decreases when the gear position is larger than a predetermined position. The variable valve timing control device that includes a valve timing control means for controlling the variable valve timing mechanism is set to its gist.

Here, that the gear position is small means that the gear position is at a low gear position such as a first speed, a second speed, or the like. Further, in the invention described in claim 2, a variable valve timing mechanism for adjusting the opening / closing timing of at least one of an intake valve and an exhaust valve provided in the internal combustion engine, and whether the internal combustion engine is in a deceleration state A gear position detecting means for detecting a parameter corresponding to a gear ratio between an output shaft of the internal combustion engine and a driving wheel axle of the vehicle; A variable valve timing control means for controlling the variable valve timing mechanism such that the smaller the gear position detected by the gear position detection means is, the larger the valve overlap amount is. The gist is a timing control device.

According to a third aspect of the present invention, in the variable valve timing control apparatus according to the first or second aspect, the deceleration state determining means may include a throttle valve provided in an intake passage of the internal combustion engine. When in a closed state and when the intake pressure in an intake passage downstream of the throttle valve is lower than a predetermined value, or when supply of fuel to a combustion chamber of the internal combustion engine is stopped. The gist is to judge that the vehicle is in a deceleration state.

According to a fourth aspect of the present invention, in the variable valve timing control apparatus according to any one of the first to third aspects, the valve timing control means may be arranged so that the rotational speed of the internal combustion engine is a predetermined rotational speed. Smaller than
The gist of the invention is to allow control of the valve overlap amount to be small.

(Operation) According to the first aspect of the present invention, at least one of the opening and closing timing of the intake valve and the exhaust valve provided in the internal combustion engine mounted on the vehicle is determined by:
It is adjusted by a variable valve timing mechanism. Also, whether or not the internal combustion engine is in a deceleration state is determined by a deceleration state determination unit. Further, a parameter corresponding to a gear ratio between the output shaft of the internal combustion engine and the drive wheel shaft of the vehicle is detected by the gear position detecting means. When the gear position detected by the gear position detecting means is smaller than the predetermined position when the deceleration state determining means determines that the internal combustion engine is in a decelerating state, the valve overlap amount is determined by the valve timing control means. The variable valve timing mechanism is controlled so as to increase, and when the gear position is larger than the predetermined position, the variable valve timing mechanism is controlled so that the valve overlap amount decreases.

Here, when the gear position is smaller than the predetermined position, the engine brake is originally in a state where it is easily applied, so that even if the valve overlap amount becomes large, the effect of the engine brake is not easily disturbed. Also,
By increasing the valve overlap amount, the degree of vacuum in the combustion chamber of the internal combustion engine does not decrease, and so-called "oil rise" is prevented.

Further, when the gear position is larger than the predetermined position, the intake pressure of the internal combustion engine does not fluctuate rapidly even if the vehicle is in a deceleration state, so that the pressure fluctuation in the combustion chamber of the internal combustion engine is small. That is, there is a tendency that so-called "oil rise" hardly occurs. In such a case, by controlling the valve overlap amount to be small, a degree of vacuum in the combustion chamber is ensured to some extent, and a reduction in pumping loss is suppressed. Therefore, even when the gear position is larger than the predetermined position, deterioration of the effectiveness of the engine brake is suppressed.

According to the second aspect of the present invention, when the deceleration state determination means determines that the internal combustion engine is in a deceleration state, the valve timing control means detects the gear position detected by the gear position detection means. Is smaller, the variable valve timing mechanism is controlled such that the valve overlap amount becomes larger.

Therefore, as the gear position is smaller, the engine brake is more effective. However, in this case, the valve overlap amount is larger, so that "oil rising" is also prevented.

Further, as the gear position is larger, the "oil rise" tends to be less likely to occur. However, in this case, the valve overlap amount is smaller, so that the deterioration of the engine braking effect is suppressed.

Further, according to the third aspect of the present invention,
In addition to the functions of the invention described in claims 1 and 2, the deceleration state determination means may include a state in which a throttle valve provided in an intake passage of the internal combustion engine is in a fully closed state and is located downstream of the throttle valve. When the intake pressure in the intake passage is lower than a predetermined value, or when the supply of fuel to the combustion chamber of the internal combustion engine is stopped, it is determined that the vehicle is in the deceleration state.

Further, according to the invention described in claim 4,
In addition to the effects of the invention as set forth in claims 1 to 3, the valve timing control means allows the valve overlap amount to be controlled to be small when the rotation speed of the internal combustion engine is lower than a predetermined rotation speed. .

Here, when the rotation speed of the internal combustion engine is equal to or higher than the predetermined rotation speed, the intake pressure of the internal combustion engine may fluctuate rapidly when the internal combustion engine is decelerated. For this reason, in the present invention, only when the intake pressure of the internal combustion engine does not fluctuate rapidly, the valve overlap amount is allowed to be controlled to be small, so that the so-called “oil rise” is more unlikely to occur. Become.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a multi-cylinder gasoline engine 1 (only one cylinder is shown) provided with the variable valve timing control device of the present embodiment. The cylinder 2 of the engine 1 mounted on the vehicle includes:
Piston 3 that moves up and down with rotation of crankshaft
Is housed. A combustion chamber 4 is formed above the piston 3, and an intake passage 5 and an exhaust passage 6 communicate with the combustion chamber 4. The communication portion between the combustion chamber 4 and the intake passage 5 is an intake port 7, which is opened and closed by an intake valve 9 movably mounted on a cylinder head 8. The communication portion between the combustion chamber 4 and the exhaust passage 6 is an exhaust port 11.
Is opened and closed by an exhaust valve 12 attached to the cylinder head 8 so as to be vertically movable.

Each of the intake valve 9 and the exhaust valve 12 has a stem 9a, 12a extending upward.
a, a valve spring 1 in a compressed state
3, 14 and valve lifters 15, 16 and the like are assembled. An intake camshaft 17 and an exhaust camshaft 18 are rotatably provided above the valve lifters 15 and 16, and the camshafts 17 and 18 have cams 17 a for opening and closing the intake valve 9 and the exhaust valve 12. , 1
8a are integrally formed. Intake side camshaft 17
Timing pulleys 21 and 22 are attached to each end of the exhaust side camshaft 18.
Reference numerals 1 and 22 are connected to the crankshaft by a timing belt.

The valve springs 13, 14
Means that the valve lifters 15 and 16 always have the cams 17a and 18a
, The intake valve 9 and the exhaust valve 12 are urged upward. This biasing direction depends on the intake port 7.
And the direction in which the exhaust port 11 is closed. Therefore, when the rotation of the crankshaft is transmitted to each of the timing pulleys 21 and 22 via the timing belt, the intake-side camshaft 17 and the exhaust-side camshaft 18 rotate.
As a result, the cams 17a and 18a
When the valve lifters 15 and 16 are periodically pressed down against the urging forces of the valve lifters 15 and 16,
Pushes the intake valve 9 and the exhaust valve 12 downward to open and close.

In the intake passage 5, a fuel injection valve 23 is mounted near the intake port 7. In the intake passage 5 upstream of the fuel injection valve 23, a throttle valve 25 that is opened and closed in conjunction with operation of an accelerator pedal 24 is provided. By opening and closing the throttle valve 25, the amount of intake air to the intake passage 5 is adjusted. Further, a surge tank 26 for smoothing the pulsation of the intake air is provided between the fuel injection valve 23 and the throttle valve 25.

A mixture of the fuel injected from the fuel injection valve 23 and the outside air introduced into the intake passage 5 is introduced into the combustion chamber 4 through the intake port 7 when the intake valve 9 is opened. You. In order to ignite the air-fuel mixture introduced into the combustion chamber 4, a spark plug 2
7 is attached. The ignition plug 27 is driven based on an ignition signal distributed by a distributor 28. The distributor 28 distributes the high voltage output from the igniter 29 to the ignition plug 27 in synchronization with the crank angle of the engine 1. And
The mixture introduced into the combustion chamber 4 is exploded and burned by the ignition of the spark plug 27, and the driving force of the engine 1 is obtained via the piston 3, the crankshaft, and the like. When the exhaust valve 12 is opened, the burned gas burned in the combustion chamber 4 flows from the exhaust port 11 to the exhaust passage 6.
Is discharged to the outside through

In this embodiment, the following various sensors are provided to detect the operating state of the engine 1.
In the vicinity of the throttle valve 25, it is detected whether or not the throttle valve 25 is in a fully closed state.
A throttle opening sensor 31 for detecting the throttle opening TA when not in the fully closed state is attached. The surge tank 26 is provided with an intake pressure sensor 32 for detecting the intake pressure PM. Further, the distributor 28 is provided with a rotor 28a that rotates in conjunction with the rotation of the engine 1, and is provided with a rotation speed sensor 33 that detects the engine rotation speed NE from the rotation of the rotor 28a. A water temperature sensor 34 for detecting a cooling water temperature THW is attached to the cylinder block 19 of the engine 1.

Further, in this embodiment, a manual transmission 40 for transmitting the output of the output shaft of the engine 1 to the drive wheel axle of the vehicle is mounted, and the output of the engine 1 is changed according to the shift position at that time. The gear ratio between the shaft and the drive wheel shaft of the vehicle is switched. The manual transmission 40 is provided with a shift position sensor 40A for detecting a current shift position (a parameter corresponding to a gear ratio). In the present embodiment, the gear position detecting means is constituted by the shift position sensor 40A. A vehicle speed sensor 30 for detecting a vehicle speed SPD at that time is provided near the manual transmission 40.

In addition to the basic configuration of the engine 1 described above, in the present embodiment, a variable valve timing mechanism 35 for adjusting the opening / closing timing of the intake valve 9 is provided as shown in FIG. Next, the variable valve timing mechanism (VVT) 35 will be described in detail.

The tip of the intake side camshaft 17 (FIG. 2)
The left end of the timing pulley 21 has a substantially disk shape, a large number of external teeth 21a are formed on the outer periphery thereof, and a boss 21b is formed at the center. In addition, external teeth 2
A tubular portion 21c is formed at an intermediate portion between 1a and the boss 21b. Then, the timing pulley 21 is
At b, it is fitted to the outer periphery of the distal end portion of the intake side camshaft 17 so as to be relatively rotatable.

An inner sleeve 36 is attached to a tip end surface of the intake side camshaft 17. The inner sleeve 36 includes a large cylindrical portion 36a and a small cylindrical portion 3 extending to the opposite side.
6b, the large cylindrical portion 36a is fitted to the outer periphery of the boss 21b, and the inner sleeve 36 is rotatable relative to the timing pulley 21. Further, the inner sleeve 36 is fixed to the tip end of the intake side camshaft 17 by a bolt 37 and a knock pin 38 so as not to rotate relatively. The inner sleeve 36 restricts the timing pulley 21 from moving in the axial direction of the intake camshaft 17.

The timing pulley 21 and the inner sleeve 36 are connected by an outer sleeve 39. The outer sleeve 39 includes an outer cylindrical portion 39a and an inner cylindrical portion 39b.
And has a double cylindrical shape. Outer sleeve 3
9 is the cylindrical portion 21 of the timing pulley 21.
c of the inner sleeve 3 of the outer sleeve 39
9b is inserted between the cylindrical portion 21c of the timing pulley 21 and the large cylindrical portion 36a of the inner sleeve 36.

Further, the large cylindrical portion 36 of the inner sleeve 36
Helical teeth 36c, 39c, 39d, 21d are formed on the outer periphery of a, the inner periphery of the inner cylindrical portion 39b of the outer sleeve 39, and the inner periphery of the cylindrical portion 21c of the timing pulley 21. These helical teeth 36c, 39c, 39d, and 21d are meshed with each other. Due to the meshing relationship, when the outer sleeve 39 moves in the axial direction, the timing pulley 2
The intake-side camshaft 17 rotates relative to 1.

A timing belt 41 is mounted on the external teeth 21a of the timing pulley 21, and the rotation of the crankshaft is transmitted to the timing pulley 21 by the timing belt 41 as described above. Accordingly, the transmission of this rotational force causes the timing pulley 21 and the inner sleeve 36 connected by the outer sleeve 39 to rotate integrally, and furthermore, the bolt 37 and the knock pin 38
As a result, the intake camshaft 17 connected to the inner sleeve 36 is integrally rotated.

In the vicinity of the outer sleeve 39, a step motor 42 for moving the outer sleeve 39 in the axial direction of the intake camshaft 17 is provided. As is well known, the step motor 42 is a motor that rotates by a predetermined angle when a pulse signal is input, and a drive cylinder 43 having an open rear surface is attached to an output shaft thereof. An outer screw 43a is threaded around the outer periphery of the drive cylinder 43 to form a worm gear. A tubular guide member 45 is fixed to the step motor 42 so as to cover the drive cylinder 43.

The driving cylinder 43 is rotatably fitted to the outer periphery of the small cylinder portion 36b of the inner sleeve 36, and penetrates the center of the outer sleeve 39. On the other hand, a bearing 44 having an inner thread 44a on the inner periphery is attached to the outer sleeve 39 so as to be relatively rotatable. The inner screw 44a of the bearing 44 and the outer screw 43 of the drive cylinder 43
are engaged with each other.

An axially extending groove 44b is formed in a part of the outer peripheral surface of the bearing 44.
A projection 45a provided on the inner periphery of the guide member 45 is engaged. The projection 45a prevents the bearing 44 from rotating and allows the bearing 44 to move in the axial direction. Therefore, when the step motor 42 is driven and the driving cylinder 43 is rotated by a predetermined angle while the timing pulley 21 and the intake camshaft 17 are rotating integrally,
The bearing 44, which is prevented from rotating, is moved in the axial direction. Accordingly, the outer sleeve 39 to which the bearing 44 is attached is moved in the same axial direction, and a relative rotation occurs between the timing pulley 21 and the intake camshaft 17, and the intake camshaft 17 is twisted. Granted.

As described above, in the variable valve timing mechanism 35 of this embodiment, the position of the outer sleeve 39 in the axial direction is changed by controlling the driving of the stepping motor 42. As a result, the intake camshaft 1
7 is twisted. Thereby, the closing timing of the intake valve 9 is adjusted. In the present embodiment, when the drive cylinder 43 of the step motor 42 rotates forward, the outer sleeve 39 moves rightward in FIG. 2 and the opening / closing timing of the intake valve 9 is advanced (advanced). Further, when the drive cylinder 43 rotates in the reverse direction, the outer sleeve 39 is moved to the left in FIG. 3 so that the opening / closing timing of the intake valve 9 is delayed (retarded).

Oil passages 46 and 47 are formed inside the intake-side camshaft 17, and lubricating oil is supplied to the inside of the timing pulley 21 through the oil passages 46 and 47.

As shown in FIG. 1, the throttle opening sensor 31, intake pressure sensor 32, rotation speed sensor 33, water temperature sensor 34, shift position sensor 40A and vehicle speed sensor 3
Numeral 0 is electrically connected to an input side of an electronic control unit (ECU) 48 constituting a valve timing control means.
The output side of the ECU 48 is provided with a step motor 42.
Are electrically connected. The ECU 48 includes a central processing unit (hereinafter referred to as a CPU) 49, a read-only memory (hereinafter referred to as a ROM) 51, a random access memory (hereinafter referred to as a RAM) 52, an input port 53, and an output port 54. They are connected to each other by a bus 55. The CPU 49 executes various arithmetic processing according to a preset control program, and the ROM 51 stores in advance a control program and initial data necessary for the CPU 49 to execute the arithmetic processing. Also, RAM
52 temporarily stores the calculation result of the CPU 49.

The CPU 49 controls the throttle opening sensor 31, the intake pressure sensor 32, the rotation speed sensor 33, the water temperature sensor 34, and the shift position sensor 40 via the input port 53.
A and signals from the vehicle speed sensor 30 are input. CPU4
9 outputs a drive signal to the step motor 42 in order to control the closing timing of the intake valve 9 according to these detection signals.

Next, the processing operation of the ECU 48 in the variable valve timing control device configured as described above will be described. That is, FIG. 3 is a flowchart showing a “VVT control routine” for controlling the opening / closing timing of the intake valve 9 among the processes executed by the ECU 48, and is executed by interruption every predetermined crank angle.

When the processing shifts to this routine, the ECU
48, first, in step 101, the basic step number VVTBASE based on the currently detected operating state.
Is calculated. In this calculation, a map or the like set in advance for parameters representing various operating states is taken into consideration.

Next, at step 102, the ECU 4
8 determines whether or not the vehicle is currently in a deceleration state. For example, when the current throttle opening TA detected by the throttle opening sensor 31 is zero and the current intake pressure PM detected by the intake pressure sensor 32 is lower than a predetermined value (negative pressure state). In some cases, it is determined that the vehicle is currently decelerating. Alternatively, it may be determined that the vehicle is in the deceleration state when the fuel cut is currently being performed. If the vehicle is not currently in the deceleration state, in step 100, the basic step number VVTB
ASE is directly set as the target step number VSTEP, and the subsequent processing is temporarily terminated.

On the other hand, if the vehicle is currently in the deceleration state, the process proceeds to step 103. In step 103, the current engine speed NE detected by the speed sensor 33 is changed to a predetermined engine speed NE1.
It is determined whether it is smaller than. If the engine speed NE is equal to or higher than the predetermined engine speed NE1, that is, if the engine speed is high, the routine jumps to step 105. If the engine speed NE is smaller than the predetermined engine speed NE1, that is, if the engine speed is low, the process proceeds to step 104.

In step 104, the ECU 48
The current N / V ratio (NVR) is a predetermined N / V
It is determined whether it is greater than the V ratio (NVR1). Here, the N / V ratio (NVR) is a value obtained by dividing the engine speed NE at that time by the vehicle speed SPD at that time. This N / V ratio (NVR) can be a parameter corresponding to the gear position (however, the reciprocal of NVR can correspond to the shift position). Then, the current N / V ratio (N
If (VR) is larger than the predetermined N / V ratio (NVR1), the process proceeds to step 105 assuming that the gear position is small.

After shifting from step 103 or step 104, in step 105, the ECU 48 sets a value obtained by adding a predetermined value α to the currently calculated basic step number VVTBASE as a target step number VSTEP,
Thereafter, the processing is temporarily terminated.

On the other hand, if the current N / V ratio (NVR) is not larger than the predetermined N / V ratio (NVR1), the process proceeds to step 106 assuming that the gear position is large. Then, in step 106, the ECU 48 sets a value obtained by subtracting the predetermined value β from the basic step number VVTBASE calculated this time as the target step number VSTEP,
Thereafter, the processing is temporarily terminated.

As described above, the "VVT control routine"
In the above, when the engine 1 is in a deceleration state, the target step number VSTEP is made variable in accordance with the current gear position and the engine speed NE, and the valve overlap amount is controlled.

Next, the operation and effect of this embodiment will be described. In this embodiment, when it is determined that the engine 1 is in the decelerating state, the engine speed NE is increased to the predetermined speed NE1.
If the current gear position is smaller than the predetermined position (when NVR> NVR1), V is set so that the valve overlap amount becomes large.
The VT 35 is controlled, and when the gear position is larger than the predetermined position (when NVR ≦ NVR1), the VVT 35 is controlled such that the valve overlap amount is reduced.

Here, when the gear position is smaller than the predetermined position, the engine brake is originally in a state where it is easily applied, so that even if the valve overlap amount becomes large, the effect of the engine brake is hardly hindered. Also,
By increasing the valve overlap amount, the degree of vacuum in the combustion chamber of the internal combustion engine does not decrease, and so-called "oil rise" is prevented. As a result, useless oil consumption can be suppressed without deteriorating the effectiveness of the engine brake.

When the gear position is larger than the predetermined position, the intake pressure PM does not fluctuate abruptly even in the deceleration state, so that the pressure fluctuation in the combustion chamber 4 of the engine 1 is small. That is, there is a tendency that so-called "oil rise" hardly occurs. In such a case, by controlling the valve overlap amount to be small, a certain degree of vacuum in the combustion chamber 4 is ensured, and a reduction in pumping loss is suppressed. Therefore, even when the gear position is larger than the predetermined position, deterioration of the effectiveness of the engine brake is suppressed. As a result, even in such a case, useless oil consumption can be suppressed without deteriorating the effectiveness of the engine brake.

In the present embodiment, even when it is determined that the engine 1 is in the deceleration state, if the engine speed NE is equal to or higher than the predetermined speed NE1,
The VVT 35 is controlled such that the valve overlap amount increases regardless of the gear position. That is, only when the engine speed NE is lower than the predetermined speed NE1, it is allowed to control the valve overlap amount to be small.

Here, when the engine speed NE is equal to or higher than the predetermined speed NE1, when the engine 1 is decelerated, the intake pressure PM may fluctuate rapidly. Therefore, in the present embodiment, only when the intake pressure PM does not fluctuate abruptly, the valve overlap amount is allowed to be controlled to be small, so that the so-called “oil rise” is more unlikely to occur. Become. As a result, the above operation and effect can be further ensured.

It should be noted that the present invention is not limited to the above-described embodiment, and may be carried out as follows by appropriately changing a part of the configuration without departing from the spirit of the invention. (1) In the above embodiment, the displacement angle of the VVT 35 is variably controlled based on the current N / V ratio (NVR). On the other hand, the displacement angle of the VVT 35 in the deceleration state may be variably controlled according to the current shift position detected by the shift position sensor 40A.

(2) In the above embodiment, the engine 1 is in the deceleration state, and the engine speed NE is equal to the predetermined speed NE.
When it is smaller than 1, the valve overlap amount is increased or decreased depending on whether the current gear position is smaller than a predetermined position (NVR> NVR1 or not). On the other hand, as shown in FIG. 4, the target step number VSTEP may be made variable according to the current gear position (N / V ratio). That is, control may be performed so that the valve overlap amount increases as the gear position decreases.

Therefore, as the gear position is smaller, the engine brake is more effective. However, in this case, the valve overlap amount is larger, so that "oil rising" can be prevented. Further, as the gear position is larger, "oil rise" tends to be less likely to occur, but in this case, the valve overlap amount is smaller, so that the deterioration of the engine braking effect is also suppressed. From these facts, by performing this control, the operation and effect described in the above embodiment can be further ensured.

(3) In the above embodiment, the engine 1 is in the deceleration state, and the engine speed NE is equal to the predetermined speed NE.
When the gear position is smaller than 1 and the current gear position is smaller than the predetermined position, the basic step number VVTBASE is set so that the valve overlap amount increases.
Is subtracted by a predetermined value β from the target step number VSTEP.
It was decided to set as. On the other hand, it may be set to the most retarded side so that the valve overlap amount becomes maximum.

(4) In the above-described embodiment, the valve timing is controlled by controlling the step motor 42.
The VT may be used to control the hydraulic control valve.
It is also possible to adopt a vane type VVT.

(5) In the above embodiment, the intake valve 9
Although the opening / closing timing of the exhaust valve 12 is controlled, the opening / closing timing of the exhaust valve 12 may be controlled. (6) In the above-described embodiment, the vehicle equipped with the manual transmission 40 has been embodied. However, the present invention can be embodied also with the case equipped with an automatic transmission.

[0058]

As described above in detail, the variable valve timing control device according to the present invention has an excellent effect that unnecessary oil consumption can be suppressed without deteriorating the effectiveness of the engine brake. .

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a variable valve timing control device according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a variable valve timing mechanism.

FIG. 3 is a flowchart illustrating a “VVT control routine” executed by an ECU.

FIG. 4 is a graph (map) showing a relationship between a target step number and an N / V ratio in another embodiment.

[Explanation of symbols]

1: engine as internal combustion engine, 9: intake valve, 12
... exhaust valve, 30 ... vehicle speed sensor, 31 ... throttle opening sensor, 32 ... intake pressure sensor, 33 ... rotation speed sensor,
35 ... Variable valve timing mechanism (VVT), 40A ...
Shift position sensor, 48... ECU constituting valve timing control means.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ identification code FI F02D 41/04 320 F02D 41/04 320 41/12 320 41/12 320 (58) Investigated field (Int.Cl. ⁷ , DB Name) F02D 13/00-28/00 F02D 29/00-29/06 F02D 41/00-41/40 F02D 43/00-45/00 F01L 1/34

Claims (4)

(57) [Claims] 1. A variable valve timing mechanism provided in an internal combustion engine for adjusting opening / closing timing of at least one of an intake valve and an exhaust valve; and a deceleration state determination for determining whether the internal combustion engine is in a deceleration state. Means, gear position detecting means for detecting a parameter corresponding to a gear ratio between an output shaft of the internal combustion engine and a drive wheel shaft of the vehicle, and the internal combustion engine is determined to be in a decelerated state by the deceleration state determining means. When the gear position detected by the gear position detecting means is smaller than a predetermined position, the variable valve timing mechanism is controlled so that the valve overlap amount becomes large, and when the gear position is larger than the predetermined position, Valve timing control means for controlling the variable valve timing mechanism so that the valve overlap amount is reduced. A variable valve timing control device. 2. A variable valve timing mechanism provided in the internal combustion engine for adjusting the opening / closing timing of at least one of an intake valve and an exhaust valve; and a deceleration state determination for determining whether the internal combustion engine is in a deceleration state. Means, gear position detecting means for detecting a parameter corresponding to a gear ratio between an output shaft of the internal combustion engine and a drive wheel shaft of the vehicle, and the internal combustion engine is determined to be in a decelerated state by the deceleration state determining means. And a valve timing control means for controlling the variable valve timing mechanism such that the smaller the gear position detected by the gear position detection means, the larger the valve overlap amount. apparatus. 3. The deceleration state determination means, wherein a throttle valve provided in an intake passage of the internal combustion engine is in a fully closed state, and an intake pressure in an intake passage downstream of the throttle valve is lower than a predetermined value. 3. The vehicle according to claim 1, wherein when the vehicle is in a low state, or when the supply of fuel to the combustion chamber of the internal combustion engine is stopped, it is determined that the vehicle is in a deceleration state. Variable valve timing control device. 4. The valve timing control means according to claim 1, wherein when the rotation speed of the internal combustion engine is lower than a predetermined rotation speed, the valve timing control means allows the valve overlap amount to be controlled to be small. 4. The variable valve timing control device according to any one of 1 to 3.