JP2827638B2 - 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 device provided with a variable valve timing mechanism for varying the opening and closing timing of an intake valve according to the operating state of an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, adjustment of an intake air amount related to output control of an internal combustion engine has been generally performed by controlling opening and closing of a throttle valve provided in the middle of an intake passage. However, at a partial load when the throttle valve is not fully opened, a negative pressure is generated in the intake passage during the intake stroke of the engine, causing a pumping loss at the time of intake of the air-fuel mixture, resulting in a large friction and a deterioration in fuel efficiency.

Therefore, Japanese Patent Application Laid-Open No. 59-119007 proposes to abolish the throttle valve and to provide a variable valve timing mechanism (VVT) for changing the opening / closing timing of the intake valve immediately before the combustion chamber. Was. By driving and controlling the VVT by operating the accelerator pedal to change the opening / closing timing of the intake valve, the amount of intake air to the combustion chamber is adjusted to reduce pumping loss, thereby improving fuel efficiency. .

[0004] By the way, the technology of an evaporative fuel emission suppression device for reducing the amount of evaporative fuel (vapor) released into the atmosphere from the fuel system of an internal combustion engine is already known. As a typical example of this device, an activated carbon canister is used, and vapor generated from a fuel tank or the like when the engine is stopped is
It is led to a canister filled with activated carbon and adsorbed.
On the other hand, during engine operation, the vapor adsorbed on the activated carbon is purged into the intake passage using the negative pressure generated in the intake passage,
Combustion is performed together with the air-fuel mixture sucked into the combustion chamber. Also, activated carbon after purging a certain amount of vapor will restore its ability to adsorb vapor from the fuel system again.

[0005] It is conceivable to employ such an evaporative fuel emission suppression device in an internal combustion engine equipped with the above-mentioned VVT.

[0006]

However, when an evaporative emission control device is employed in an internal combustion engine equipped with a VVT as described above, the evaporative emission control device operates as intended due to the operation of the VVT. There was a risk of disappearing. In other words, the main purpose of the VVT is to reduce the pumping loss of the engine, that is, to reduce the negative pressure in the intake passage to make it closer to the atmosphere. Therefore, by operating the VVT, the negative pressure itself generated in the intake passage is reduced or the negative pressure itself is eliminated. Therefore, a negative pressure required to operate the evaporative fuel emission suppression device cannot be obtained, and it may be difficult to purge the vapor from the canister. In addition, as a result, the vapor may overflow from the canister.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to reduce pumping loss of an internal combustion engine and to utilize the negative pressure generated in an intake passage for fuel vapor from a fuel system. It is an object of the present invention to provide a valve timing control device for an internal combustion engine which can reliably purge the intake passage through an intake passage.

[0008]

In order to achieve the above object, according to the present invention, as shown in FIG. 1, the motor is driven at a predetermined timing in synchronization with the rotation of the internal combustion engine M1,
An intake valve M5 and an exhaust valve M6 for opening and closing an intake passage M3 and an exhaust passage M4, respectively, which communicate with the combustion chamber M2;
A variable valve timing mechanism M7 driven to change the opening / closing timing of the intake valve M5;
Operating state detecting means M8 for detecting the operating state of the internal combustion engine M based on the detection result of the operating state detecting means M8.
1 to reduce the pumping loss of the intake valve M5.
And a first drive control means M9 for driving and controlling the variable valve timing mechanism M7 to control the opening / closing timing of the internal combustion engine. A canister M10, a purging means M11 for purging the fuel vapor adsorbed by the canister M10 into the intake passage M3 by utilizing a negative pressure generated in the intake passage M3, and detecting a value corresponding to an adsorbed state of the fuel vapor in the canister M10 Based on the detection results of the adsorption state detection means M12, the operation state detection means M8, and the adsorption state detection means M12, it is determined that the condition in which the canister M10 has adsorbed a predetermined amount or more of the fuel vapor and the fuel vapor should be purged. When it is determined, at least the closing timing among the opening and closing timings of the intake valve M5. The second driving control means for driving and controlling the variable valve timing mechanism M7 so as to advance M13
And

[0009]

According to the above arrangement, as shown in FIG. 1, during operation of the internal combustion engine M1, the intake valve M5 and the exhaust valve M
6 is driven at a predetermined timing in synchronization with the rotation of the internal combustion engine M1, the intake passage M3 and the exhaust passage M4 are respectively opened and closed, and the intake and exhaust in the combustion chamber M2 is performed. The operating state detecting means M8 detects the operating state of the internal combustion engine M1. Then, the first drive control means M9 drives and controls the variable valve timing mechanism M7 based on the detection result of the operation state detection means M8 to control the opening / closing timing of the intake valve M5 so as to reduce the pumping loss of the internal combustion engine M1. I do.

On the other hand, the evaporated fuel generated in the fuel system of the internal combustion engine M1 is temporarily adsorbed by the canister M10. Further, the purge execution means M11 operates to purge the adsorbed fuel vapor into the intake passage M3 by utilizing the negative pressure generated in the intake passage M3. Here, canister M
The value corresponding to the adsorption state of the evaporated fuel in 10 is detected by the adsorption state detecting means M12. Then, based on the detection results of the operation state detection means M8 and the adsorption state detection means M12, the second drive control means M13 sets a condition in which the canister M10 adsorbs a predetermined amount or more of the evaporated fuel and purges the evaporated fuel. When it is determined that the opening timing of the intake valve M5 is higher, the variable valve timing mechanism M7 is drive-controlled so as to advance at least the closing timing of the opening / closing timing of the intake valve M5.

Therefore, only before the canister M10 is filled with the evaporated fuel, the closing timing of the intake valve M5 is advanced, and the negative timing in the intake passage M3 is advanced only when the conditions for purging the evaporated fuel are met. The generation of pressure is promoted. Therefore, it is possible to use the negative pressure generated in the intake passage M3 when the purge execution means M11 operates.

[0012]

【Example】

(First Embodiment) A first embodiment of a valve timing control apparatus for an internal combustion engine according to the present invention will now be described with reference to FIGS.
This will be described in detail with reference to FIG.

FIG. 2 is a schematic structural view (only one cylinder is shown) illustrating the gasoline engine 1 as an internal combustion engine mounted on the vehicle of 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 intake valve 9 for opening and closing is mounted on an intake port 7a opening to the combustion chamber 6 of the intake passage 7. An exhaust valve 8 for opening and closing is provided in an exhaust port 8a opening to the combustion chamber 6 of the exhaust passage 8.
Is assembled.

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 80 constituting a fuel system by the operation of a fuel pump (not shown). When the intake valve 9 is opened, a mixture of fuel and outside air injected from the injector 11 and taken into the intake passage 7 is supplied to the intake port 7.
a to the combustion chamber 6. 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 is provided downstream of the throttle valve 13. Furthermore, throttle valve 1
The upstream side of the air flow meter 3 is provided with a well-known air flow meter 16 for detecting an intake air amount Q taken into the intake passage 7 from the outside.
Is 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 camshaft 21 on the intake side and the camshaft 22 on the exhaust side supported by the cylinder head 5 by the number of all cylinders. The intake valve 9 and the exhaust valve 10 are urged upward by the urging forces of the valve springs 17 and 18 and in a direction to close the intake port 7a and the exhaust port 8a. In this biased state, each stem 9
The upper ends of a and 10a are always in contact with the cams 21a and 22a via the valve lifters 19 and 20.

In this embodiment, in order to make only the opening / closing timing of the intake valve 9 variable, the camshaft 21 on the intake side is made variable.
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. The timing pulley assembly 24 and the timing pulley 26 are drivingly connected to a 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.
The intake valve 9 and the exhaust valve 10 move downward, and the intake port 7a and the exhaust port 8a are opened. As is well known, the basic opening and closing timings of the intake valve 9 and the exhaust valve 10 include four strokes of the piston 3 performed during two rotations of the crankshaft (an intake stroke, a compression stroke, and a compression stroke).
It is set in advance in relation to the vertical movement accompanying the expansion stroke and the exhaust stroke. Here, when the intake port 7a 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. or,
The exhaust port 8a is moved by the upward movement of the piston 3 during the exhaust stroke.
Is opened, 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 rotation 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 synchronizes the high voltage output from the igniter 29 with the crank angle of the engine 1 and
7 for distribution. Distributor 2
Reference numeral 8 denotes a rotor 2 which rotates in conjunction with the rotation of the engine 1.
8a, and a rotation speed sensor 30 for detecting the engine speed NE from the rotation of the rotor 28a. Further, the distributor 28 is provided with a cylinder discriminating sensor 31 which 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 position signal G.

The above-described throttle sensor 14, fully-closed switch 14a, air flow meter 16, rotation speed sensor 30
The cylinder discriminating sensor 31 constitutes operating state detecting means for detecting the operating state of the engine 1.
A cooling water temperature sensor 32 for detecting the cooling water temperature (cooling water temperature) THW. In the middle of the exhaust passage 8, an oxygen sensor 33 for detecting the oxygen concentration Ox 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. This vehicle speed sensor 34
It is attached to a transmission (not shown) and is driven by rotation of its gear.

In addition, in this embodiment, a canister 81 capable of temporarily adsorbing the evaporated fuel (vapor) in the fuel tank 80 is provided. This canister 81
Constitutes an evaporative fuel discharge suppression device for reducing the amount of vapor released from the fuel tank 80 into the atmosphere, in which activated carbon for vapor adsorption is stored. In addition, an introduction passage 82 communicating with the fuel tank 80 is connected to the canister 81.
The vapor introduced into the canister 81 through the introduction passage 82 is adsorbed on the activated carbon inside the canister 81. On the other hand, a purge passage 83 extending from the canister 81 is connected to the surge tank 15 in order to purge the vapor temporarily absorbed by the canister 81 into the intake passage 7. Further, between the purge passage 83 and the surge tank 15, a vacuum switching valve (VS) composed of an electromagnetic two-way valve that is driven to open and close is provided.
V) 84 are provided. This VSV 84 is “ON”
As a result, the valve is opened to allow the communication between the purge passage 83 and the surge tank 15, and when the valve is turned off, the valve is closed to shut off the communication between the two.

Therefore, for example, when the engine 1 is stopped,
Vapor generated from the fuel tank 80 is guided to the canister 81 and is sucked. Also, the purge passage 83 and V
The purge execution means is constituted by the SV 84 and the like. When the VSV 84 is opened during operation of the engine 1, the vapor temporarily absorbed by the canister 81 utilizes the negative pressure generated on the downstream side of the throttle valve 13. The surge tank 15 is purged. Furthermore, surge tank 15
The vapor purged to the combustion chamber 6 through the intake passage 7
The fuel is supplied to the combustion together with the air-fuel mixture sucked into the air. Then, the activated carbon after purging a certain amount of vapor from the canister 81 restores the ability to adsorb the vapor from the fuel tank 80 again.

In addition, in this embodiment, the canister 81
Is provided with a weight sensor 85. The weight sensor 85 detects an activated carbon weight Wx that changes in proportion to the amount of vapor adsorbed on activated carbon, as a value corresponding to the adsorption state of vapor in the canister 81.

As shown in FIG. 2, the throttle sensor 14, the fully-closed switch 14a, the air flow meter 16, the rotational speed sensor 30, the cylinder discriminating sensor 31, the water temperature sensor 32, the oxygen sensor 33, the vehicle speed sensor 34 and the like are provided. An engine electronic control unit (hereinafter simply referred to as “engine ECU”) 40 is electrically connected to an input side. The injector 11 and the igniter 29 described above are electrically connected to the output side of the engine ECU 40. Then, the engine ECU 40 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 output signal from the controller.

In this embodiment, the engine ECU 40
Is a control device that mainly controls fuel injection amount control and ignition timing control of the engine 1. In addition, in this embodiment, as shown in FIG. 2, a first drive for controlling the drive of the VVT 23 is provided. A VVT ECU 41 that constitutes control means is provided. The VVT ECU 41 controls the rotation direction and the rotation amount of the output shaft of the step motor 25. For this purpose, the throttle valve opening degree TA, the fully closed signal LL, the intake air amount Q, the engine speed NE, the oxygen concentration Ox, the detected value of the vehicle speed SP, and the like are input from the engine ECU 40 to the input side of the VVT ECU 41 as data signals. . Also, the activated carbon weight Wx from the weight sensor 85 is input to the input side of the VVT ECU 41. And V
The VTECU 41 determines the magnitude of the valve overlap according to the operating state of the engine 1 based on the input data signal and the like in order to control the opening / closing timing of the intake valve 9 so as to reduce the pumping loss of the engine 1. Then, a valve timing control signal for suitably controlling the step motor 25 is output from the output side. In addition, the VVT ECU 41 constitutes a purge execution unit and a second drive control unit. Based on an input data signal or the like, the VVT ECU 41 should purge the vapor in a state where the canister 81 has adsorbed a predetermined amount or more of vapor. When it is determined that the condition is satisfied, the VVT 2 is opened such that the VSV 84 is opened and the closing timing of the intake valve 9 is advanced.
3 is drive-controlled.

Next, the aforementioned engine ECU 40 and V
The configuration of the VT ECU 41 will be described with reference to the block diagrams of FIGS. FIG. 3 is a block diagram illustrating an electrical configuration of the engine ECU 40. Engine ECU
Reference numeral 40 denotes a central processing unit (CPU) 42, a read-only memory (ROM) 4 in which a predetermined control program and the like are stored in advance.
3. A random access memory (RAM) 44 for temporarily storing the calculation results of the CPU 42, a backup RAM 45 for storing previously stored data, and the like, and these components, an external input circuit 46, an external output circuit 47, and the like are connected by a bus 48. It is configured as a connected theoretical operation circuit.

The external input circuit 46 is connected to the aforementioned throttle sensor 14, fully closed switch 14a, air flow meter 16, rotation speed sensor 30, cylinder discrimination sensor 31, water temperature sensor 32, oxygen sensor 33, and vehicle speed sensor 34, respectively. ing. On the other hand, the injector 11, the igniter 29, and the VVT ECU 41 are connected to the external output circuit 47, respectively.

Then, the CPU 42 reads, as input values, signals from the fully closed switch 14a, the air flow meter 16, and the sensors 14, 30 to 34, etc., which are input via the external input circuit 46. When reading this input value,
In the external input circuit 46, input values from the throttle sensor 14, the air flow meter 16, the water temperature sensor 32, and the oxygen sensor 33 are subjected to analog / digital conversion processing. In the external input circuit 46, 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 suitably controls the injector 11 and the igniter 29 based on the input values read from the fully closed switch 14a, the air flow meter 16, the sensors 14, 30 to 34, and the like.

The CPU 42 includes a throttle opening degree TA and a full closing signal LL among signals read as input values from the full closing switch 14a, the air flow meter 16, the sensors 14, 30 to 34, and the like via the external input circuit 46. , Intake air amount Q, engine speed NE, oxygen concentration Ox, and vehicle speed S
P or the like as a data signal via the external output circuit 47 as VV
Output to TECU 41.

FIG. 4 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. In addition, VVT
The ECU 41 includes a latch circuit 57 connected to the output port 54, a gate 58, and a drive circuit 59.

The input / output port 53 is connected to the engine ECU 40. Also, a weight sensor 85 is connected to the input / output port 53. Further, the gate 58 is connected to the step motor 25, and the drive circuit 59 is connected to VSV.

The MPU 50 controls the throttle opening TA and the fully closed signal LL input through the input / output port 53,
Signals such as the engine speed NE and the vehicle speed SP are read as input values, and the step motor 25 is suitably controlled based on the read input values. That is, the MPU 50 calculates and determines the direction to rotate the step motor 25 and the number of steps according to the control program stored in the ROM 51 based on the read input value, and latches the calculation result as a valve timing control signal via the output port 54. Output to the circuit 57. The latch circuit 57 receives the valve timing control signal, and outputs a gate 58 opening / closing command according to a predetermined sequence to execute the signal. And
The gate 58 selects an electromagnetic coil to be excited and drives the step motor 25 according to the opening / closing command.

The MPU 50 is provided with a throttle opening TA, a fully closed signal LL, an intake air amount Q, an engine speed NE, an oxygen concentration Ox, and a vehicle speed S input through the input / output port 53.
Signals such as P and activated carbon weight Wx are read as input values, and the VSV 84 is suitably controlled based on the read input values. That is, the MPU 50 determines the conditions for purging the vapor in accordance with the control program stored in the ROM 51 based on the read input values, and drives the VSV 84 to open and close via the drive circuit 59 according to the determination result.

Next, the configuration of the above-described VVT 23 will be described in detail with reference to FIG. The camshaft 21 on the intake side that drives the intake valve 9 has its cam journal 2
At 1b, it is rotatably supported by the cylinder head 5. Then, 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, and a space between the boss 62a and the circumferential wall 62b is a circumferential groove 62c. Helical teeth 62d are formed on the inner periphery of the circumferential wall 62b. The pulley main body 62 is mounted on the camshaft 21 with 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 63a 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 is attached to the outer peripheral wall 6.
4a and an inner peripheral wall 64b.
4c 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 a and the inner peripheral wall 64b.
The inner peripheral wall 64b of the cylindrical gear 64 and the circumferential groove 6
4f is a circumferential wall 62b and a circumferential groove 62 of the pulley body 62.
It is assembled in an uneven relationship with c.

In this assembled state, the helical teeth 62d, 63c, 64d, and 64e are meshed with each other. Due to the meshing relationship, the cylindrical gear 64 is relatively rotatable with the camshaft 21 by moving in the axial direction. I have. 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.

Accordingly, by transmitting the driving force from the crankshaft to the timing pulley assembly 24, the pulley main body 62 and the inner cap 63 connected by the cylindrical gear 64 are integrally rotated. The camshaft 21 connected to the inner cap 63 is driven to rotate integrally.

The above-described 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 cylinder 6 of the inner cap 63.
3b so as to be rotatable relative to each other, and is disposed so as to pass through a hole 64c of the cylindrical gear 64. 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 assembled by a ball bearing 69 so as to be relatively rotatable. The ring gear 68 is meshed on the outer periphery of the worm gear 67, and is movable in the axial direction by the 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 6 extending in the axial direction is provided on the outer periphery of the ring gear 68 on the step motor 25 side.
8b are formed. At the same time, a detent member 70, which has a tubular shape and extends toward the timing pulley assembly 24, is attached to the casing of the step motor 25. On the inner periphery of the detent member 70, the aforementioned long groove 6 is provided.
A projection 70a engaging with the projection 8b is formed. And
Due to the relationship between the engagement of 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.

Accordingly, when the timing pulley assembly 24 and the camshaft 21 are being rotated integrally, 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. Accordingly, the cylindrical gear 64 is moved in the same axial direction, a relative rotation occurs between the pulley main body 62 and the camshaft 21, and the camshaft 21 is twisted. As described above, in the VVT 23 of this embodiment, the drive of the step motor 25 is controlled so that the cylindrical gear 6 is driven.
The position of the camshaft 21 in the axial direction is changed, so that the camshaft 21 is twisted. When the camshaft 21 is twisted, 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.
1 and 72 are formed, and lubricating oil is supplied to the inside of the timing pulley assembly 24 through the oil passages 71 and 72.

Next, the operation of the valve timing control device for an internal combustion engine configured as described above will be described with reference to FIGS. FIG. 6 is a flowchart for explaining a “VVT control routine” executed by the VVT ECU 41 to drive and control the VVT 23, and is executed by a periodic interruption every predetermined time.

After the engine 1 is started, when the processing shifts to this routine, first, in step 101,
From the engine ECU 40, the throttle opening TA, the fully closed signal LL, the engine speed NE, and the vehicle speed SP detected by the throttle sensor 14, the fully closed switch 14a, the speed sensor 30, and the vehicle speed sensor 34 are read.

Subsequently, in step 102, it is determined whether or not the vehicle is running normally based on the fully closed signal LL and the vehicle speed SP. That is, it is determined whether the fully closed signal LL is not “ON” and the vehicle speed SP is not “0”. Then, if the vehicle is not running normally, the subsequent processing is once ended as it is.

If it is determined in step 102 that the vehicle is traveling normally, in step 103, the previously read engine speed NE and throttle opening TA
And a function f (N
E, TA) is set as an advance angle value θCAM for opening / closing timing control of the intake valve 9. The calculation of the function f (NE, TA) is performed with reference to a map as shown in FIG. Here, the map of FIG.
In advance. In this map, a function f () for controlling the opening / closing timing of the intake valve 9 so as to reduce the pumping loss of the engine 1 in accordance with changes in the throttle opening TA and the engine speed NE, that is, changes in the load on the engine 1. NE, TA) are set.

Subsequently, at step 104, in order to drive and control the step motor 25, the target step number Vs corresponding to the advance angle value θCAM is set from the previously set advance angle value θCAM.
Set t.

Thereafter, at step 105, the stepping motor 25 is deduced from the set target step number Vst.
Is set as the control step number STEP.

Next, at step 106, it is determined whether or not the control step number STEP is "0". Here, when the control step number STEP is “0”,
The subsequent processing is once ended without driving the step motor 25.

On the other hand, if the number of control steps STEP is not “0” in step 106,
In 7, 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 STEP
Is a positive number, after resetting the control flag DIR to “0” in step 108,
Move to 11.

If the control step number STEP is a negative number in step 107, step 109
, The control flag DIR is set to "1". Next, at step 110, the number of control steps STE
After the absolute value of P is set as the new control step number STEP, the process proceeds to step 111.

Then, step 108 or step 11
In step 111 after shifting from 0, it is determined whether or not the control flag DIR is "1". Here, when the control flag DIR is “1”, step 112
, The step motor 25 of the intake side VVT 23 is set to 1
After the step has been reversed, the process proceeds to step 114. If the control flag DIR is "0", the flow proceeds to step 114 after the step motor 25 is rotated forward by one step in step 113.

After shifting from step 112 or 113, in step 114, the number of control steps ST
A result obtained by subtracting “1” from EP is set as a new control step number STEP. In step 115, it is determined whether or not the new control step number STEP is "0". Then, the new control step number ST
If the EP is not “0”, the process jumps to step 111 and repeats the processing of steps 111 to 115. 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 115, the subsequent processing is once ended as it is. As described above, the drive of the VVT 23 is controlled by the control of the step motor 25,
The opening / closing timing of the intake valve 9 is controlled.

Next, a processing operation for purging the vapor adsorbed by the canister 81 into the intake passage 7 will be described. FIG. 8 is a flowchart for explaining a "purge control routine" executed by the VVT ECU 41 to drive and control the VSV 84 and the VVT 23, and is executed by a periodic interruption every predetermined time.

When the processing shifts to this routine, first, at step 201, the throttle sensor 14, the fully closed switch 14a, the air flow meter 16 and each sensor 3
The throttle opening TA, the fully closed signal LL, the intake air amount Q, the engine speed NE, the oxygen concentration Ox, and the vehicle speed SP based on the detection of 0, 33, and 34 are read from the engine ECU 40, respectively. Further, the activated carbon weight Wx is read from the weight sensor 85.

Next, in step 202, it is determined whether or not the purge execution condition is satisfied. This determination is made based on “OFF” of the fully closed signal LL, the vehicle speed SP equal to or higher than a predetermined value, the intake air amount Q larger than the idling equivalent value, and the oxygen concentration O.
It is determined that the purge execution condition is satisfied when all the conditions for the feedback condition of the air-fuel ratio determined from x and the like are satisfied. If the purge execution condition is not satisfied, the subsequent processing is temporarily terminated without executing the purge.

On the other hand, if the purge execution condition is satisfied, it is determined in step 203 whether the activated carbon weight Wx is equal to or more than the predetermined amount α. That is, the canister 81
Is determined to be in a state in which more than a predetermined amount of vapor that is not full is adsorbed. If the activated carbon weight Wx is not equal to or larger than the predetermined amount α, it is determined that there is a sufficient amount of vapor adsorbed in the canister 81, and the subsequent processing is temporarily terminated without executing the purge.

On the other hand, if the activated carbon weight Wx is equal to or more than the predetermined amount α in step 203, the VSV 84 is turned on to open the valve in step 204 to purge the vapor from the canister 81.

Subsequently, at step 205, a purge advance value θPA for advancing the closing timing of the intake valve 9 is calculated. The calculation of the purge advance value θPA is performed by referring to a predetermined map based on the throttle opening TA, the engine speed NE, and the like.
The purge advance value θPA is determined by referring to the map shown in FIG.
Is a value set in advance so as to advance by a predetermined angle. That is, the advance value θCAM is mainly determined by the engine 1
, Ie, a value for reducing the negative pressure generated in the intake passage 7 so as to approach the atmosphere.
On the other hand, the purge advance value θPA is a value for promoting the generation of a negative pressure in the intake passage 7.

Thereafter, in step 206, in order to drive and control the step motor 25, the target step number Vst corresponding to the previously set purge advance value θPA is set from the previously set purge advance angle θPA.

Then, in step 207, processing for controlling the drive of the step motor 25 is performed based on the set target step number Vst, and the subsequent processing is temporarily terminated. Here, the process for controlling the drive of the step motor 25 is described in “V
Steps 105 to 115 of "VT Control Routine"
Here, a detailed description is omitted here as it is equivalent to the processing of FIG.

In this way, the VSV 84 is opened, and the VVT 23 is controlled by the step motor 25.
Is controlled so that the closing timing of the intake valve 9 is controlled.

As described above, according to the valve timing control apparatus of this embodiment, the VVT 23 is driven and controlled in accordance with the operating state of the engine 1, that is, the load state, so that the pumping loss of the engine 1 is reduced. The opening / closing timing of the valve 9 is controlled. Therefore, since the pumping loss can be reduced, the intake air amount Q to the combustion chamber 6 can also be increased in the operation region equal to or more than the medium load region,
The output of the engine 1 and the fuel efficiency can be improved.

FIG. 9 shows the valve timing control device of this embodiment, in which the shaft torque of the engine 1, the negative pressure of the intake pipe (the negative pressure in the intake passage 7), and the closing angle of the intake valve 9 (the closing angle ( 6 is a time chart for explaining a change in the intake valve 9 closing timing).
In this time chart, the valve timing is VV
The case where it is made variable by T23 is shown by a solid line, and the case where it is kept at the base valve timing is shown by a broken line. As is clear from this time chart, in the region where the throttle opening TA is small, the closing angle of the intake valve 9 by the VVT 23 is constant similarly to the base valve timing.
It can be seen that the shaft torque is controlled by the intake pipe load that decreases as the throttle opening TA increases. That is, it is understood that the output torque is controlled by the intake air amount Q that increases with the increase in the throttle opening TA. On the other hand, in the region where the throttle opening TA is large, it can be seen that the intake pipe negative pressure hardly disappears and the shaft torque does not change. In the middle range of the throttle opening TA, the negative pressure of the intake pipe gradually decreases. However, when the closing angle is varied by the VVT 23, the negative pressure of the intake pipe is generated as compared with the case where the base valve timing is maintained. As a result, it can be seen that they are relatively suppressed. That is, according to the valve timing control device of this embodiment, it is understood that the pumping loss is reduced by lowering the intake pipe negative pressure as compared with the case where the base valve timing is maintained.

On the other hand, according to the valve timing control device of this embodiment, the vapor generated in the fuel tank 80 is guided through the introduction passage 82 and is temporarily adsorbed by the activated carbon of the canister 81. Therefore, it is possible to prevent the vapor generated in the fuel tank 80 from being released into the atmosphere.

During the operation of the engine 1, the purge execution condition for purging the vapor adsorbed by the canister 81 into the intake passage 7 is satisfied.
When the amount of vapor adsorbed at the time is equal to or more than a predetermined amount, the VSV 84 is opened to allow communication between the purge passage 83 and the surge tank 15, and the canister 81 is connected to the surge tank 15. At the same time, the drive control of the VVT 23 is performed so that the closing timing of the intake valve 9 is advanced by a predetermined angle from the relatively advanced closing value θCAM for reducing the pumping loss.

Therefore, before the canister 81 is filled with the vapor, the closing timing of the intake valve 9 is advanced only when the purge execution condition is satisfied, and the generation of the negative pressure in the intake passage 7 is promoted. Therefore, when the vapor is to be purged from the canister 81, the negative pressure generated in the intake passage 7 can be used. By utilizing the generated negative pressure, the vapor adsorbed by the canister 81 can be reliably purged to the surge tank 15 through the purge passage 83.

That is, according to the valve timing control device of this embodiment, the pumping loss of the engine 1 can be reduced in accordance with the operating state of the engine 1, and the vapor from the fuel tank 80 is discharged when the purge execution condition is satisfied. By using the negative pressure generated in the intake passage 7, the intake passage 7 can be reliably purged. Moreover, since the vapor can be purged before the canister 81 becomes full of vapor, it is possible to prevent the vapor from overflowing from the canister 81 beforehand.

(Second Embodiment) Next, a second embodiment of the internal combustion engine valve timing control apparatus according to the present invention will be described with reference to FIG. Note that the configuration of the valve timing control device in this embodiment is basically the same as that of the first embodiment, and the same members are denoted by the same reference numerals and description thereof will be omitted. Only the points will be described.

FIG. 10 is a sectional view showing the structure near the throttle valve 13 in the valve timing control device of this embodiment. The throttle valve 13 is rotatably supported in the intake passage 7 about a support shaft 13a. A pulley 86 is fixed to one end of the support shaft 13a, and a wire 87 wound around the pulley 86 is
It is connected to. Accordingly, in conjunction with the operation of the accelerator pedal 12, the throttle valve 13 is opened and closed via the wire 87 and the pulley 86.

In this embodiment, when the purge is performed, the amount of vapor guided from the canister 81 to the surge tank 15 through the purge passage 83 and the VSV 84 is increased or decreased in proportion to the opening of the throttle valve 13. Purge throttle mechanism 88 linked to the opening and closing of
Is provided.

That is, the purge throttle mechanism 88 has a casing 89, and the casing 89 is fixed to the intake passage 7 by bolts 90. The interior of the casing 89 is divided into two chambers 89b and 89c by a partition wall 89a, and the other end of the support shaft 13a extending through the intake passage 7 is arranged in one of the chambers 89b.
In the other chamber 89c, two ports 89d and 89e communicating with the outside are formed. This other room 89c
Inside is a partition wall 8 located between both ports 89d and 89e.
9f, a valve hole 89g is formed in the center of the partition wall 89f. One end of a purge passage 83 extending from the canister 81 is connected to one port 89d, and one end of the purge passage 83 extending to the VSV 84 is connected to the other port 89e.

The support shaft 13 arranged in one chamber 89b
A needle valve 91 is attached to a so as to extend in the axial direction of the coaxial 13a. The needle valve 91 is screwed to the support shaft 13a by a male screw 91a provided on the base end side thereof.
9a to the other chamber 89c, and further to a valve hole 89g.
It is arranged corresponding to. A key 91c is projected on the shaft of the needle valve 91, and a key groove 89h is formed in the casing 89 so as to be engaged with the key 91c and extend in parallel with the needle valve 91. When the throttle valve 13 is opened and closed and the support shaft 13a is rotated, the needle valve 91 does not rotate integrally with the support shaft 13a, but rotates by the engagement relationship between the key 91c and the key groove 89h. It is moved in the axial direction while being stopped.
When the needle valve 91 is moved, the valve element 91b opens and closes the valve hole 89g to open both ports 89d and 89e.
The communication between is opened and closed. That is, the needle valve 91 is opened and closed. In this embodiment, as shown in FIG.
3 is set such that the effective passage area (opening) between the valve hole 89g and the valve element 91b becomes largest in the fully opened state, and the opening degree of the valve hole 89g becomes smallest in the fully closed state of the throttle valve 13. ing.

Accordingly, as the opening of the throttle valve 13 decreases, the needle valve 91 is gradually closed, and the purge passage 83 is throttled by the purge throttle mechanism 88, so that the passage of vapor through the purge passage 83 is suppressed. In other words, the purge throttle mechanism 88 controls the purge flow rate of the vapor into the intake passage 7 in proportion to the opening of the throttle valve 13, that is, the intake air amount Q of the intake passage 7 when the VSV 84 is open. Has become.

Next, the operation of the valve timing control device configured as described above will be described. When the purge execution condition is satisfied during the operation of the engine 1 and the amount of vapor adsorbed in the canister 81 becomes a predetermined amount or more, the VVT ECU 41 opens the VSV 84 to purge the vapor in the canister 81. At the same time, the closing timing of the intake valve 9 is changed to the relatively advanced closing angle θ to reduce the pumping loss.
VVTEC to advance the CAM by a predetermined angle
U41 drives and controls VVT23.

Accordingly, the closing timing of the intake valve 9 is advanced to promote the generation of a negative pressure in the intake passage 7, and by utilizing the generated negative pressure, the vapor adsorbed by the canister 81 is removed from the purge passage. Surge tank 1 through 83
5 can be reliably purged.

When the opening of the throttle valve 13 is large, the opening of the purge throttle mechanism 88 is also large, and a large amount of vapor is purged in accordance with the large amount of intake air Q passing through the intake passage 7. be able to. On the other hand, when the opening of the throttle valve 13 is small, the opening of the purge throttle mechanism 88 is also small, so that a small amount of vapor can be purged in accordance with the small amount of intake air Q passing through the intake passage 7.

Therefore, also in the valve timing control device of this embodiment, the pumping loss of the engine 1 can be reduced in accordance with the operating state of the engine 1, and when the vapor execution condition is satisfied, the vapor from the fuel tank 80 is removed from the intake passage. By using the negative pressure generated in the intake passage 7, the intake passage 7 can be reliably purged. Moreover, since the vapor can be purged before the canister 81 becomes full of vapor, it is possible to prevent the vapor from overflowing from the canister 81 beforehand.

At the same time, the purge flow from the canister 81 to the intake passage 7 can be suppressed as the opening of the throttle valve 13 decreases, that is, as the intake air amount Q decreases, by the action of the purge throttle mechanism 88. Therefore, the purge flow rate taken into the intake passage 7 in the light load region of the engine 1 does not become too large, and the fuel amount supplied to the combustion chamber 6 due to the excessive purge flow rate does not increase too much, and stable air-fuel ratio control is performed. And the stable operation of the engine 1 can be ensured.

The present invention is not limited to the above-described embodiments, but may be implemented as follows by appropriately changing a part of the configuration without departing from the spirit of the invention. (1) In each of the above embodiments, the weight sensor 85 for detecting the activated carbon weight Wx in the canister 81 is provided as the adsorption state detecting means for detecting the value corresponding to the adsorption state of the vapor in the canister 81.
An HC meter for detecting the concentration of hydrocarbon (HC) inside the canister 81 may be provided. In addition, a temperature sensor that detects the reaction heat of activated carbon that changes according to the amount of vapor adsorbed inside the canister 81 or a sensor that detects the presence or absence of refueling of the fuel tank 80 is provided as an adsorption state detection unit. Or you may.
Alternatively, the VVT ECU 41 itself may be used as the adsorption state detecting means to temporarily execute the purge when executing the air-fuel ratio control,
A change in the feedback correction coefficient (FAF) at that time may be used to detect whether the amount of vapor suction in the canister 81 is large or small.

(2) In the second embodiment, the purge throttle mechanism 88 is provided in combination with the VSV 84 that is simply turned on and off in order to control the purge flow according to the opening of the throttle valve 13. The purge throttle mechanism 88 may be omitted and the VSV 84 may be duty-controlled according to the opening of the throttle valve 13.

(3) In each of the above embodiments, the case where only the closing timing of the intake valve 9 is made variable by the VVT 23 has been embodied. Embody,
This may be embodied in a case where both the closing and opening timings of the intake valve 9 are made variable.

(4) In each of the above embodiments, the intake side VVT 23 driven by the stepping motor 25 is employed, but a hydraulically driven VVT may be employed. (5) In each of the embodiments described above, the present invention is embodied in the gasoline engine 1, but it may be embodied in a diesel engine.

[0086]

As described in detail above, according to the present invention,
Evaporated fuel in the fuel system can be temporarily absorbed in a valve timing control device that drives and controls a variable valve timing mechanism according to the operating state of the internal combustion engine to control the opening and closing timing of the intake valve so as to reduce the pumping loss of the internal combustion engine The evaporative fuel adsorbed in the canister is purged to the intake passage by utilizing the negative pressure generated in the intake passage, and the evaporative fuel is removed while the canister adsorbs a predetermined amount or more of the evaporative fuel. When the condition to be purged is satisfied, since the drive control of the variable valve timing mechanism is performed so as to advance at least the closing timing of the opening and closing timing of the intake valve, the pumping loss of the internal combustion engine can be reduced and Before the canister is filled with evaporative fuel,
The generation of a negative pressure in the intake passage is promoted only when the conditions for purging the evaporated fuel are satisfied. When necessary, the evaporated fuel from the fuel system is utilized by utilizing the negative pressure generated in the intake passage. Therefore, an excellent effect that the vapor can be prevented from overflowing from the canister can be prevented.

[Brief description of the drawings]

FIG. 1 is a conceptual configuration diagram illustrating a basic conceptual configuration of the present invention.

FIG. 2 is a schematic configuration diagram illustrating a gasoline engine according to a first embodiment of the present invention.

FIG. 3 is a block diagram illustrating an electrical configuration of an engine ECU according to the first embodiment.

FIG. 4 is a block diagram illustrating an electrical configuration of a VVT ECU according to the first embodiment.

FIG. 5 is a cross-sectional view illustrating a configuration of a VVT according to the first embodiment.

FIG. 6 is a flowchart illustrating a “VVT control routine” executed by a VVT ECU in the first embodiment.

FIG. 7 is a map in which the relationship of the advance value to the engine speed and the throttle opening in the first embodiment is determined in advance.

FIG. 8 is a flowchart illustrating a “purge control routine” executed by the VVT ECU in the first embodiment.

FIG. 9 is a time chart for explaining changes in an engine shaft torque, an intake pipe negative pressure, and an intake valve closing angle with respect to the magnitude of a throttle opening in the first embodiment.

FIG. 10 is a sectional view showing the vicinity of a throttle valve showing a purge throttle mechanism in a second embodiment of the invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine as an internal combustion engine, 6 ... Combustion chamber, 7 ... Intake passage, 8 ... Exhaust passage, 9 ... Intake valve, 10 ... Exhaust valve, 14 ... Throttle sensor, 14a ... Fully closed switch,
16 ... air flow meter, 30 ... rotation speed sensor, 33 ...
Oxygen sensor, 34 ... vehicle speed sensor (14, 14a, 16,
Reference numerals 30, 33, and 34 constitute operating state detection means), 23 ... variable valve timing mechanism (VVT), 4
DESCRIPTION OF SYMBOLS 1 ... VVT ECU which comprises 1st drive control means, purge execution means, and 2nd drive control means, 80 ... fuel tank which comprises a fuel system, 81 ... canister, 83 ... purge passage, 84 ... VSV (83, 84 , 41 constitute a purge execution means), 85 ... weight sensors for detecting the suction state.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-69715 (JP, A) JP-A-3-156148 (JP, A) JP-A-4-301147 (JP, A) 90338 (JP, U) Fully open 1986-625642 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F02D 13/02 F01L 1/34 F02D 43/00 301 F02M 25/08 301

Claims (1)

(57) [Claims] An intake valve and an exhaust valve that are driven at a predetermined timing in synchronization with the rotation of an internal combustion engine to open and close an intake passage and an exhaust passage that communicate with a combustion chamber, respectively, and that the opening and closing timing of the intake valve is made variable. A variable valve timing mechanism that is driven for operating the engine; an operating state detecting unit that detects an operating state of the internal combustion engine; and the intake air that reduces a pumping loss of the internal combustion engine based on a detection result of the operating state detecting unit. A valve timing control device for an internal combustion engine, comprising: first drive control means for driving and controlling the variable valve timing mechanism to control the opening / closing timing of a valve. A canister; and evaporating the fuel adsorbed by the canister using a negative pressure generated in the intake passage. Purging executing means for purging the intake passage; adsorbing state detecting means for detecting a value corresponding to an adsorbing state of the evaporated fuel in the canister; and detecting the operating state detecting means and the adsorbing state detecting means. When it is determined that the vaporized fuel is adsorbed at a fixed amount or more and the conditions for purging the vaporized fuel are determined, the variable valve timing mechanism is driven to advance at least the closing timing of the opening and closing timing of the intake valve. A valve timing control device for an internal combustion engine, comprising: second drive control means for controlling.