JPH11218035A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of a shock when overlap is increased, in an internal combustion engine having valve characteristic control devices arranged to respective intake valve and exhaust valve. SOLUTION: When a load is rapidly increased from a low load to a high load, first, variation from a position on the delay side of the phase of an intake cam shaft 50 to a position on the advance side by an intake valve characteristic control device 100 is started. After the variation reaches a given ratio of a whole variation amount, variation from a position on the advance side of the phase of an exhaust cam shaft 50 deg. to a position on the delay side by an exhaust valve characteristic control device 100 deg. is started.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an internal combustion engine having a valve characteristic control device for variably controlling the opening and closing characteristics of a valve, and more particularly to an internal combustion engine having valve characteristic control devices for both an intake valve and an exhaust valve.

[0002]

2. Description of the Related Art An internal combustion engine is known which has a valve characteristic control device for controlling the opening and closing characteristics of each of an intake valve and an exhaust valve so as to change the overlap (see Japanese Patent Application Laid-Open No. 9-79056). . By the way, if the overlap period in which both the exhaust valve and the intake valve are open is increased, the volume efficiency is improved. Therefore, the overlap is increased when the load requiring a high output is increased. However, when the load is increased in this manner, another control parameter, for example, the fuel amount is also increased to increase the output. In addition, when the improvement of the volumetric efficiency due to the increase of the overlap is superimposed, the output increases sharply, which may cause a shock.

[0003] In particular, when a valve characteristic control device is provided for each of the intake valve and the exhaust valve as in the device of the above-mentioned publication, the overlap is often increased, and it is necessary to consider the above problem. However, none of the above-mentioned problems have been considered.

[0004]

SUMMARY OF THE INVENTION In view of the above problems, the present invention has been made to prevent a shock from occurring when an overlap is increased in an internal combustion engine equipped with a valve characteristic control device for each of an intake valve and an exhaust valve. The purpose is to do.

[0005]

According to the claimed invention,
Operating load detecting means for detecting an operating load, target valve opening / closing timing storing means for storing target opening / closing timing of an intake valve and an exhaust valve set according to the operating load, and opening / closing of the intake valve at the set target opening / closing timing An intake valve characteristic control device that adjusts the opening / closing timing of the intake valve so that the exhaust valve opens and closes at the set target opening / closing timing. The target opening / closing timing stored in the valve opening / closing timing storage means is the intake first opening / closing timing with the intake valve opening / closing timing lagging with respect to the first stage light load, and the exhaust valve opening / closing timing with the advanced side exhaust timing. At the first timing, the opening / closing timing of the intake valve advances with respect to the second stage medium load. The opening / closing timing of the exhaust valve is the first exhaust timing on the advanced side at the second intake timing on the side, and the opening / closing timing of the intake valve is the second intake timing on the advanced side for the third stage high load. When the opening / closing timing of the exhaust valve is the exhaust second timing on the lag side and the load is increased by only one stage, an internal combustion engine that changes only the opening / closing timing of either the intake valve or the exhaust valve is provided. .

In the internal combustion engine configured as described above, when the load is increased by only one stage, only the opening / closing timing of either the intake valve or the exhaust valve is changed, and the overlap does not increase rapidly.

According to a second aspect of the present invention, in the first aspect of the invention, when the load is rapidly increased from a light load to a high load, the intake valve opening / closing timing of the intake valve by the intake valve characteristic control device is controlled by the first intake valve. After the change from the timing to the intake second timing reaches a predetermined ratio to the total change amount, the change of the opening / closing timing of the exhaust valve by the exhaust valve characteristic control device from the exhaust first timing to the exhaust second timing is started. An internal combustion engine is provided.

In the internal combustion engine configured as described above, when the load is rapidly increased from a light load to a high load, the intake valve opening / closing timing of the intake valve opening / closing timing by the intake valve characteristic control device is changed from the intake first timing to the intake second timing. After the change to the predetermined amount with respect to the total change amount, the change of the opening / closing timing of the exhaust valve from the exhaust first timing to the exhaust second timing by the exhaust valve characteristic control device is started, and the opening / closing timing of the intake valve is started. And simultaneous change of the opening and closing timing of the exhaust valve is avoided, and the overlap does not increase rapidly.

According to a third aspect of the present invention, in the first aspect of the invention, when the load is rapidly reduced from a high load to a light load, the intake valve opening / closing timing of the intake valve opening / closing timing by the intake valve characteristic control device is increased. There is provided an internal combustion engine configured to simultaneously start the change from the timing to the intake first timing and the change of the exhaust valve opening / closing timing from the exhaust second timing to the exhaust first timing by the exhaust valve characteristic control device. .

In the internal combustion engine configured as described above, when the load is rapidly reduced from a high load to a light load, the opening and closing timing of the intake valve and the opening and closing timing of the exhaust valve are not overlapped at the same time. It is changed, and the unstable combustion due to the sudden decrease of the load is suppressed.

According to a fourth aspect of the present invention, in the first aspect of the present invention, when the load is reduced from a high load to a medium load, the exhaust valve opening / closing timing of the exhaust valve opening / closing timing by the exhaust valve characteristic control device is changed from the second exhaust timing. In addition to the change to the first exhaust timing, the opening / closing timing of the intake valve by the intake valve characteristic control device is simultaneously changed from the second intake timing to the first intake timing. There is provided an internal combustion engine adapted to change the opening / closing timing from a first intake timing to a second intake timing.

In the internal combustion engine configured as described above, when the load is reduced from a high load to a medium load, the opening / closing timing of the intake valve and the opening / closing timing of the exhaust valve are simultaneously returned without overlap, and thereafter, Since the opening / closing timing of the intake valve is changed, combustion instability due to a decrease in load is suppressed.

According to a fifth aspect of the present invention, in the first aspect of the invention, when the opening / closing timing of the exhaust valve is changed from the first exhaust timing to the second exhaust timing as the load increases to a high load, There is provided an internal combustion engine adapted to change the fuel injection timing of a fuel injection valve such that fuel is injected during a period in which an exhaust valve is closed and an intake valve is open before a change is started.

In the internal combustion engine configured as described above, when the opening / closing timing of the exhaust valve is changed from the first exhaust timing to the second exhaust timing as the load increases to a high load, before the change is started, The fuel injection timing of the fuel injection valve is changed such that fuel is injected during a period in which the exhaust valve is closed and the intake valve is open, and blow-by is prevented.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram showing the overall structure of the first embodiment of the present invention. An intake port (not shown) of the engine 1 is supplied with intake air via an intake pipe 2, a surge tank 3, and an intake manifold 4. The intake pipe 2 is provided with an air cleaner 5, an air flow meter 211, and an electronic throttle 251. A fuel injection valve 252 is attached to the intake manifold 4 for each cylinder.

The electronic throttle 251 changes the throttle opening according to the amount of depression of an accelerator pedal (not shown), and also has a function as a throttle opening sensor.

On the other hand, an exhaust manifold (not shown) of the engine 1 is provided with an exhaust manifold 6. Here, the order of ignition of the engine is # 1 cylinder → # 3 cylinder → # 4 cylinder → # 2 cylinder, whereas the exhaust manifold 6 is, as shown in FIG. And # 4
The cylinders, # 2 cylinder and # 3 cylinder, are once gathered isometrically, respectively, and are further gathered into one. The length is optimized so that the exhaust port has a negative pressure during the overlap period.

A catalyst 8 is provided in an exhaust pipe 7 connected downstream of the exhaust manifold 6. An air-fuel ratio sensor 215 is provided upstream of the catalyst 8, and the fuel injection amount of the fuel injection valve 252 is feedback-controlled based on a signal from the air-fuel ratio sensor 215 so that the catalyst 8 performs an optimal purifying operation. Is done. An ignition plug 253 integrated with an igniter is provided for each cylinder of the engine 1.

The engine 1 has a crank position sensor 212 for detecting an angular position of a crankshaft, a water temperature for detecting a cooling water temperature of the engine, in addition to the above-described air flow meter 211, which is particularly related to the present invention. A cam angle sensor 214 for detecting the phases of the sensor 213, the intake camshaft 50, and the exhaust camshaft 50 ';
Sensors such as 214 ′ are provided, and signals from these sensors are sent to an electronic control unit (ECU) 200.

The air flow meter 211 generates a signal voltage corresponding to the amount of air passing through the intake pipe as a load. Although the details of the structure of the crank position sensor 212 are omitted, for example, an electromagnetic pickup is arranged near a protrusion of a signal generating disk attached to the crankshaft, and the electromagnetic pickup outputs a signal voltage every time the protrusion passes. Occur. The signal generating disk has projections at every 10 °, but there are 34 projections because two teeth are missing. Since the missing tooth portion is provided at a predetermined angle position with respect to the top dead center of the first cylinder, for example, the top dead center can be accurately obtained from the signal generated by the missing tooth portion. The signal generated at intervals of 10 ° is further divided, and the crank angle from the top dead center at the time of measurement can be accurately determined.

The engine water temperature sensor 213 generates a signal corresponding to the cooling water temperature TW of the engine 1. The intake cam angle sensor 214 and the exhaust cam angle sensor 214 'generate a signal voltage each time the electromagnetic pickup passes through the protrusion near the signal generating protrusion provided at an appropriate location on the camshaft. The projection generates a signal once per revolution of the camshaft, ie, once every two revolutions of the crankshaft. The protrusion is provided, for example, so as to generate a signal at the time of the maximum lift of the cam peak of the first cylinder.

The ECU 200 has an input interface 210 and a central processing unit (CPU) 22 connected to each other.
0, a random access memory (RAM) 230, a read only memory (ROM) 240, and an output interface 250. ECU2
The CPU 220 of the electronic control unit 200 performs calculations according to the present invention, which will be described later, from signals of the respective sensors input to the input interface 210, data stored in the ROM 240, and the like, and outputs the electronic throttle 251 and the ignition plug 253 via the output interface 250. Valve characteristic control device 1 described later
00, 100 ′ to execute the control of the present invention,
In addition, it performs feedback control of the air-fuel ratio, control of the ignition timing, and the like.

In order to change the overlap period by changing the phase of the opening period of the intake valve (not shown) and the phase of the opening period of the exhaust valve (not shown), the vane type having the same structure is used. Valve characteristic control device 10
0 and 100 'are attached to the intake camshaft 50 and the exhaust camshaft 50'. Therefore, the valve characteristic control device 100 attached to the intake camshaft 50 will be described below as an example.

Note that the same numbers with "'" are for exhaust.

FIG. 2 is a cross-sectional view of the vane type valve characteristic control device 100 attached to the intake camshaft 50, taken along a plane passing through the central axis X of the intake camshaft 50. Referring to FIG. 2, a crankshaft (not shown) is connected to a 1/1 via a chain (not shown).
The housing 20 and the side cover 30 which form the advance oil chamber 110 and the retard oil chamber 120 in cooperation with the gear 10 are B1 (only one out of four gears is shown). ). A rotor 40 is disposed inside the housing 20 so as to be rotatable by a predetermined angle. The rotor 40 is fixed to the intake camshaft 50 with bolts B2.

FIG. 3 is a view of the valve characteristic control device 1 from the shaft end side (left side in FIG. 1) with the side cover 30 and the bolts B1 and B2 removed. As shown in FIG. 3, the housing 20 has an outer peripheral portion 21 and four inner protrusions 2.
Consists of two. A sealing member 2 is provided on the inner peripheral side of the inner protrusion 22.
3 are provided. 24 is a hole through which the bolt B1 passes. In FIG. 2, the outer peripheral portion 21 and the inner protruding portion 22 of the housing 20 are shown together with the seal member 23 above the central axis X of the intake camshaft 50 and below the central axis X of the intake camshaft 50. In the figure, the outer peripheral portion 21 is shown in the housing 20, and a broken line 20a is a boundary between the outer peripheral portion 21 and the inner protruding portion 22.

Further, as shown in FIG.
Comprises a boss 41 and four vanes 42 projecting radially outward therefrom. A seal member 43 is provided on the outer peripheral side of each vane 40. In FIG. 2, the rotor 40
Shows only the boss 41 above the central axis X of the intake camshaft 50, and shows the boss 41 and the vane 42 together with the seal member 43 below the central axis X of the intake camshaft 50. Dashed line 40a is the boss 41
And the vane 42.

Hydraulic oil that has passed through the camshaft advance oil passage 55 to the boss 41 of the rotor 40 at the time of advance is guided to the central oil chamber 44 formed around the bolt B2 at the center of the boss 41. 4 introduces hydraulic oil from the inclined oil passage 45 and the central oil chamber 44 to the advance oil chamber 110 formed between the vane 42 of the rotor 40 and the inner projection 22 of the housing 20.
A distribution oil passage 46 is formed.

Returning to FIG. 2, paying attention to the intake camshaft 50, the intake camshaft 50 has a half upper metal bearing 6 between the outer flange 51 and the inner flange 52.
0A, and is rotatably supported by a cylinder head 70 and a cam cap 80 via a lower metal bearing 60B. Then, the outer flange 51 and the inner flange 5
2, the annular advance oil passage 5
3, an annular retard oil passage 54 is formed closer to the outer flange 52.

The annular advance oil passage 53 includes a camshaft advance oil passage 55 formed parallel to the central axis X and a short oil passage 55a.
Is communicated through. The camshaft advance oil passage 55 communicates with the inclined oil passage 45 of the rotor 40. The annular retard oil passage 54 communicates with a camshaft retard oil passage 56 formed parallel to the central axis X through a short oil passage 56a. The camshaft advance angle oil passage 56 is connected to the outer flange 51.
Shaft end side annular retard oil passage 57 provided on the shaft end side
Is in communication with

The shaft end side annular retard oil passage 57 communicates with a retard oil chamber 120 via an in-gear annular oil passage 11 and an in-gear distribution oil passage 12 provided on the inner peripheral side of the gear 10. I have.

On the other hand, the cylinder head 70 has an oil control valve 90 for controlling the supply of hydraulic oil to each oil chamber.
Is inserted. FIG. 4 shows the oil control valve 9.
0 is shown in detail. As shown in FIG. 4, the oil control valve 90 moves the spool valve 95 within the sleeve 91 by the plunger 93 of the electromagnetic solenoid 92 and the spring 94 to switch the flow direction of the hydraulic oil.

The sleeve 91 includes an advance port 91a, a retard port 91b, a supply port 91c, and a drain port 91.
d and 91e. On the other hand, the spool valve 95
It has one land 95a, 95b, 95c, 95d and three groove passages 95e, 95e, 95f. The electromagnetic solenoid 92 is connected to an electronic control unit (hereinafter referred to as EC).
U) Excited by duty control by a signal from 200, but by changing the duty ratio, spool valve 9
The position of 5 is changed to control the supply and discharge of hydraulic oil to the advance oil chamber 110 and the retard oil chamber 120.

For example, when energized at a duty ratio of 100%, the spool valve 95 moves to the leftmost position and the advance port 9
1a is fully open and communicates with the supply port 91c, the retard port 91b is fully open and communicates with the drain port 91e, and hydraulic oil is supplied at the maximum capacity to the advance oil chamber 110 of the valve characteristic control device 100, Hydraulic oil is discharged from the oil chamber 120 at the maximum capacity, and the intake camshaft 50 moves in the advance direction at the maximum speed with respect to the crankshaft.

Also, duty ratio 0% (not excited)
In the case of, the spool valve 95 moves to the rightmost side, the supply port 91c and the retard port 91b communicate with the full opening, the advance port 91a communicates with the drain port 91d with the full opening, and the retard oil of the valve characteristic control device 100 Hydraulic oil is supplied to the chamber 120 with the maximum capacity, hydraulic oil is discharged from the advance oil chamber 110 with the maximum capacity, and the intake camshaft 50 moves in the retard direction at the maximum speed with respect to the crankshaft.

FIG. 4 shows a state in which the supply port 91c and the retard port 91b are in full communication with each other.

On the other hand, the engine 1 has the intake cam angle sensor 214 for detecting the phase difference of the intake camshaft 50 with respect to the crankshaft as described above (see FIG. 1), and the position of the intake camshaft 50 with respect to the crankshaft. When the phase difference becomes a predetermined phase difference, the electromagnetic solenoid 92 is excited at an intermediate duty ratio, and the spool valve 95 is turned by the lands 95a, 95b, 95c, and 95d to the advance port 91a, the supply port 91c, and the drain port 91.
d, and stops at positions where the communication between the retard port 91b and the supply port 91c and the drain port 91d is cut off, and the intake camshaft 50 maintains its phase difference with respect to the crankshaft.

In FIG. 2, reference numeral 71 denotes an advance oil passage in the cylinder head for communicating the advance port 91a of the oil control valve 90 with the annular advance oil passage 53 formed in the intake camshaft 50. is there. Reference numeral 72 denotes a retard oil passage in the cylinder head for communicating the retard port 91b of the oil control valve 90 with the annular retard oil passage 54 formed in the intake camshaft 50.

Similarly, reference numeral 73 in FIG. 2 denotes a supply oil passage for communicating the supply port 91c of the oil control valve 90 with an oil pump (not shown), and reference numeral 74 denotes an oil control valve 9
This is a drain oil passage for communicating the drain pans 91d and 91e with the oil pan.

FIG. 5 is a sectional view taken along the line 4-4 in FIG. 2 and shows the communication between the annular advance oil passage 53 and the cylinder head advance oil passage 71, and the annular retard oil passage. The communication between the cylinder 54 and the retard oil passage 72 in the cylinder head is shown. As shown in FIG. 4, the cylinder head advance oil passage 71 extends upward from the advance port 91 a of the oil control valve 90 toward the cam cap 80, and extends from the cylinder head 70.
Penetrates through the upper surface 76.

A groove 82 is formed in the lower surface 81 of the cam cap 80 so as to connect the cylinder head advance oil passage 71 to the outside of the upper bearing metal 60A. On the other hand, a hole 61 is formed in the upper bearing metal 60 </ b> A, and the diameter of the hole 61 is set larger than the width of the annular advance oil passage 53. Then, the hole 61 and the cam cap 80
An inclined oil passage 83 is formed so as to communicate a groove 82 with a lower surface 81 of the oil passage.

On the other hand, the retard oil passage 72 in the cylinder head extends upward from the advance port 91a of the oil control valve 90 toward the cam cap 80, but bends obliquely on the way to open the outside of the lower bearing metal 60B. 7
2a has been reached. A crescent-shaped groove 78 having a cross section larger than the diameter of the opening 72a is formed in the cylinder head 70 that receives the lower bearing metal 60B from the opening 72a toward the axial end.

On the other hand, the lower bearing metal 60B has
A notch 62 is formed at the corner where the flange portion 60F rises.
Are formed. The size of the notch as viewed from the axial direction is at least larger than the crescent-shaped cross section of the groove 78, and the width of the notch as viewed from a direction perpendicular to the axis is the annular shape of the intake camshaft 50 inscribed in this portion. It is larger than the width of the retard oil passage 54.

Accordingly, the working oil for advancing is supplied from the advancing port 91a of the oil control valve 90 to the oil passage 71 in the cylinder head, the groove 82 of the cam cap 80, the inclined oil passage 83, and the hole 61 of the upper bearing metal 60A. Thus, it reaches the annular advance oil passage 53 of the intake camshaft 50. From the annular advance oil passage 53, through the short communication oil passage 55a, enter the camshaft advance oil passage 55, proceed toward the shaft end, and reach the central oil chamber 44 through the inclined oil passage 45 of the rotor 40, From there, through the distribution oil passage 46, each advance oil chamber 110
Distributed to

The hydraulic oil for retarding is formed between the retarding port 91b of the oil control valve 90, the oil passage 72 in the cylinder head, and between the groove 78 having a crescent cross section and the back surface of the lower bearing metal 60B. After entering the oil passage 79 and proceeding in the axial direction, the annular retarded oil passage 5 of the intake camshaft 50 passes through a notch 62 formed at a corner where the flange 60F at the shaft end of the lower bearing metal 60B rises.
Reaches four. From the annular retard oil passage 54, a short connecting oil passage 56
a, enters the camshaft retard oil passage 56, advances toward the shaft end, and reaches the shaft end side annular retard oil passage 57 through the short communication oil passage 56b. From there, the shaft end side annular retard oil passage 5
7 enters an inclined distribution oil passage 12 via an annular oil passage 11 formed in the gear 10, and is distributed to each retard oil chamber 120.

Next, optimization of the length of the exhaust manifold 6 will be described. As described above, in this engine, the length of the exhaust manifold 6 is optimized so that the pressure Pe of the exhaust port becomes negative during the overlap period. Therefore, when the throttle opening increases, the pressure at the intake port Pi becomes higher than the pressure at the exhaust port, and the intake air flows through the exhaust port. FIG. 6 is an explanatory diagram thereof.

Hereinafter, control in the embodiment of the present invention configured as described above will be described. This control
As shown in FIG. 7, the amount of overlap is set according to the load, and a shock is not generated when the amount of overlap is changed according to a change in load.

FIG. 8 shows the phases of the intake cam 50 and the exhaust cam 50 'when there is no overlap, middle and large, and they are set as follows. <When there is no overlap amount> Phase of intake cam 50: INRET on the lag side Exhaust cam 50 'phase: EXADV on the leading side <When overlap amount is medium> Phase of intake cam 50: INADV on the leading side Exhaust Phase of cam 50 ': EXADV on the leading side <When the amount of overlap is large> Phase of intake cam 50: INRET on the leading side Phase of exhaust cam 50': EXADV on the leading side

FIGS. 9A and 9B show examples of the opening start position and the opening end (closed) position of the exhaust valve and the intake valve when there is no overlap, middle and large, and FIG. In this case, (b) shows the case where the overlap is being performed, and (c) shows the case where the overlap is large.

FIGS. 10 to 13 are flowcharts for executing the control. Steps 101 to 10 in FIG.
Steps up to 6 are steps for reading each parameter. In step 107, the load, for example, the throttle opening THA,
By comparing the current value with the previous value, it is determined whether acceleration (including a constant speed) or deceleration is performed. In the case of acceleration, the process proceeds to step 108 in FIG. Go to 119.

First, the case where it is determined that acceleration has occurred will be described. The following cases are assumed for acceleration. (1) Sudden acceleration from the region without overlap (light load) to the region with large overlap (high load) in FIG. (2) Acceleration from the region without overlap (light load) in FIG. 7 to the region with overlap (medium load). (3) Acceleration from the area of the overlap (medium load) in FIG. 7 to the area of the large overlap (high load). (4) Small acceleration in each area.

In this embodiment, of the above cases,
In case (4), there is no need to change the overlap, so nothing is done. Among the cases (1) to (3), the case (1) is a feature of the present invention in that a predetermined ratio is set to a phase change amount required to change the phase of the intake camshaft 50 in order to avoid a shock. After that, the phase of the exhaust camshaft 50 'is changed before performing the operation.

The determination in step 108 is to determine whether the current phase INACT of the intake camshaft 50 does not match the target value INMAP obtained from the map.
As shown in FIG. 8, a positive determination is made in the cases (1) and (2), and a negative determination is made in the cases (3) and (4).
In the cases of (1) and (2), step 1 is performed as described above.
After a positive determination is made in step 08, the set value (command value) INS of the intake camshaft 50 is set in steps 110 and 111.
ET is set to a value INRET for increasing the overlap, and the routine proceeds to step 112.

In step 112, the exhaust camshaft 5
It is determined whether the current phase EXACT of 0 'does not match the target value EXMAP obtained from the map.
In the case of (2), since the phase of the exhaust camshaft 50 'does not change, a negative determination is made and the routine returns.
In the case of (1), an affirmative determination is made and the routine proceeds to step 113.

In step 113, the intake camshaft 50
It is determined whether or not a predetermined ratio is not reached with respect to the amount of phase change required for the phase change. Step 113
If the determination in step 114 is affirmative, the routine proceeds to step 114 in which the set value of the phase of the exhaust camshaft 50 'is set to the current value, that is, the target value EXMAP obtained from the map is stopped, and the routine returns.

When the phase change amount of the intake camshaft 50 reaches a predetermined ratio with respect to the required phase change amount, a negative determination is made in step 113. When the phase change amount of the intake camshaft 50 reaches a predetermined ratio with respect to the required phase change amount, the phase set value of the exhaust camshaft 50 'is set to the target value EXMAP obtained from the map. At 115 and 116, the change of the injection timing is completed. The change of the injection timing will be described later.

Then, after the change of the injection timing is completed, in steps 117 and 118, the set value of the phase of the exhaust camshaft 50 'is set to the target value EXMAP obtained from the map, and the routine returns.

On the other hand, in the cases of (3) and (4), a negative determination is made in step 108 and the routine proceeds to step 109. In step 109, it is determined whether or not the current phase EXACT of the exhaust camshaft 50 'does not match the target value EXMAP obtained from the map. Therefore, in the case of (4), a negative determination is made, and nothing is performed. Return without In the case of (3), an affirmative determination is made in step 109, and then, as in the case of (1), after the change of the injection timing is completed in steps 115 and 116, the exhaust cam is changed in steps 117 and 118. Shaft 50 '
Is set as the target value EXMAP obtained from the map, and the process returns.

Next, a case where it is determined that the vehicle is decelerated will be described. The following cases are assumed for deceleration. (5) Deceleration from the region of large overlap (high load) in FIG. 7 to the region of no overlap (light load). (6) Deceleration from the region of large overlap (high load) in FIG. 7 to the region of overlap (medium load). (7) Deceleration from the area of the overlap (medium load) in FIG. 7 to the area of no overlap (light load). (8) Small deceleration in each area.

In this embodiment, of the above cases,
In case (8), there is no need to change the overlap, so nothing is done. Of the cases (5) to (8), the case (6) finally ends the overlap. However, in order to avoid unstable combustion due to deceleration, the case (6) is once again used. Make sure there is no overlap before returning during overlap.

Since the determination in step 119 is whether or not the current phase EXACT of the exhaust camshaft 50 'does not match the target value EXMAP obtained from the map, FIG. In the case of 6), an affirmative determination is made, and in the cases of (7) and (8), a negative determination is made.
In the cases of (5) and (6), step 1 is performed as described above.
After an affirmative determination in step 19, in steps 120 and 121, the set value EXSET of the exhaust camshaft 50 'is set to a value EXADV for eliminating overlap.

Then, after the change of the injection timing is completed in steps 122 and 123, steps 124 and 1
25, the set value INSE of the intake camshaft 50
T is set to a value INRET for eliminating overlap.

As described above, in the case of (6), after the phase of the intake camshaft 50 is set to INRET, I
It is necessary to return to NADV. Therefore, in step 126, the set value INSET of the intake camshaft 50 is set to I
It is determined whether it is NADV. In the case of (6), a positive determination is made, but in the case of (5), a negative determination is made.

If a negative determination is made in the case (5), the process returns. If the determination in step (6) is affirmative, the routine proceeds to step 127, where the current phase INACT of the intake camshaft 50 is changed to the previous phase INACT.
Determines if it is behind _OLD . Step 12
The affirmative determination at 7 means that the phase of the intake camshaft 50 is being changed to INRET, that is, has not reached INRET, and in this case, the routine returns without doing anything.

Conversely, if a negative determination is made in step 127, it means that the phase of the intake camshaft 50 has reached INRET.
In step, the target phase INSET is set to INMAP and the process returns.

Next, the case of the above (7) will be considered. In this case, the target phase EXSET of the exhaust camshaft 50 'does not change from the table of FIG. In step 130, the current phase of the intake camshaft 50 is set to the target phase INM.
It is determined whether it is different from the AP. Therefore, in the case of (7), an affirmative determination is made, and steps 131 and 132
Sets the target phase INMAP and returns.

In the case of (8), step 1
A negative determination is made at 30 and the process returns without doing anything.

Next, the change of the overlap amount performed as described above will be described. The case where the overlap is enlarged will be described below. The enlargement of the overlap is performed by shifting the valve opening period of the intake valve to the advance side and / or shifting the valve opening period of the exhaust valve to the retard side in accordance with the command value. These are achieved by moving the rotational phases of the intake camshaft 50 and the exhaust camshaft 50 'to the advance side and the retard side, respectively. This movement of the camshaft is performed by feedback control as follows while detecting the phases of the intake camshaft 50 and the exhaust camshaft 50 'with the crank position sensor 212, the intake cam angle sensor 214, and the exhaust cam angle sensor 214'. Do it.

The current phases of the intake camshaft 50 and the exhaust camshaft 50 ′ are determined by the crank position sensor 212.
From the intake cam angle sensor 214 and the exhaust cam angle sensor 214 '. As a parameter representing this phase, the crank angle from the compression top dead center of the # 1 cylinder to the time when the intake cam angle sensor 214 and the exhaust cam angle sensor 214 'generate a signal, that is, the maximum lift of the cam of the # 1 cylinder, is set. calculate. Note that the compression top dead center is determined as a point that has passed a predetermined crank angle since the crank position sensor 212 generated the signal of the missing tooth portion as described above.

The intake valve and the exhaust valve are connected, for example, as shown in FIG.
The phase for opening and closing as shown in FIG. 8C is shown in FIG. 8, which is indicated by EXRET and INADV in FIG. 8, but actually used for measuring the camshaft phase described above. With the same parameters as above, that is, the crank from the compression top dead center of the # 1 cylinder to the time when the intake cam angle sensor 214 and the exhaust cam angle sensor 214 'generate signals, that is, the maximum lift of the cam of the # 1 cylinder. In the corner, memorized.

If the actually measured phase of the camshaft is behind the target phase value of the camshaft obtained from the map, for example, if the phase of the intake camshaft 50 is to be changed, the oil control valve 90 A command to send an exciting current having a duty ratio of 100% to the electromagnetic solenoid 92 is issued to make the working oil flow into the advance oil chamber 110 of the valve timing control device 100, and the phase of the camshaft is advanced to approach the target phase. Conversely, if the actually measured phase of the camshaft is ahead of the target phase value of the camshaft obtained from the map, a command to demagnetize the electromagnetic solenoid 92 of the oil control valve 90 is issued, and the valve timing control device The hydraulic oil is caused to flow through the retard oil chamber 120 at 100 to delay the phase of the camshaft to approach the target phase. Then, when the phase of the camshaft matches the target value, an exciting current having an intermediate duty ratio is sent to maintain the phase.

FIGS. 14 and 15 show the valve housings 20 of the valve characteristic control devices 100 and 100 'when the phase of the intake camshaft 50 is most advanced and the phase of the exhaust camshaft 50' is most retarded. , 20 'and the vanes 4 of the rotors 40, 40'.
The relative positional relationship between 2, 42 'is shown. In each of the drawings, the housings 20, 20 'and the rotors 40, 40' rotate clockwise as indicated by the arrows in the drawings. In addition, in each figure, only a minimum number is shown for easy understanding.

First, as shown in FIG.
When the phase is most advanced, the electromagnetic solenoid 92 of the oil control valve 90 is excited at a duty ratio of 100%, and the advanced oil chamber 110 is filled with the hydraulic oil introduced as shown by the thick broken arrow, and Then, all the hydraulic oil in the retard oil chamber 120 is discharged, and then the duty ratio is set to an intermediate value to maintain that state.

On the other hand, as shown in FIG.
When the phase of 0 'is most retarded, the electromagnetic solenoid 92' of the oil control valve 90 'is degaussed, and the retarded oil chamber 120' is filled with hydraulic oil introduced as shown by a thick broken arrow, Conversely, all of the hydraulic oil in the advance oil chamber 110 'is discharged, and then the duty ratio is set to an intermediate value and the state is maintained.

The oil control valves 90, 9
0 'sets the duty ratio of the electromagnetic solenoids 92 and 92' to 1
Advance ports 91a, 91a 'only after being excited to 00%
Is opened, and the retard port 91 is first turned on at 0% (demagnetization).
b, 91b 'does not open, but it is lower than 100% or larger than 0%, gradually starts to open from the duty ratio, and reaches the maximum opening at 100%, 0% (demagnetization). Yes, it does not always need to be 100% or 0%. Rather, it is not desirable to always control at 100% or 0% because overshoot occurs and it takes time to reach the target phase. Therefore, in this embodiment, the duty ratio is changed according to the difference from the target phase, but the details are omitted.

Next, the change of the injection timing in steps 115 and 116 of the flowchart of FIG. 11 and steps 122 and 123 of the flowchart of FIG. 12 will be described. In this embodiment, the fuel injection timing is basically determined according to a predetermined map based on the rotational speed and the load. When the fuel injection flag FINJ = 0, the fuel injection timing is determined according to this determination method. Is done. As is well known, the fuel is more atomized when the injection is completed before the intake valve is opened. Therefore, the map is set as such.

However, in the internal combustion engine of the present embodiment,
When the load is large, the negative pressure of the exhaust port becomes larger than the negative pressure of the intake port as described above, and when the fuel injection timing is set as described above, a part of the fuel introduced into the cylinder is exhausted together with air into the exhaust port. Unburned HC
(Hydrocarbon) emissions increase. Therefore, in this embodiment, before the phase of the exhaust camshaft 50 'is changed in accordance with the shift to a high load, the fuel injection is performed in a state where the exhaust valve is closed and the intake valve is opened after the end of the overlap. . Fuel injection flag FINJ =
At the time of 1, such fuel injection timing is set.

FIG. 15 is a flowchart showing the operation when the flag FINJ is set to 1 (step 15).
02 is affirmative, the exhaust valve closing timing TEXVC is calculated from the map of FIG. 8 (step 15).
03), a predetermined appropriate time TAS is added to the exhaust valve closing timing TEXVC, and the fuel injection valve opening timing TI is added.
BGN is determined (step 1504), and the fuel injection time TAU separately calculated at the fuel injection valve opening timing TIBGN.
Is added to determine the valve closing timing TIFIN of the fuel injection valve (step 1506). In the execution of the routine of the flowchart in FIG. 14, the air amount determination method flag FOLG is set to 0.
In the case of (NO in step 1502), in step 1505, the TI
Determine BGN.

By injecting the fuel at the timing determined in this manner, the fuel can flow into the cylinder without blowing through the exhaust port, and the air-fuel mixture having an appropriate air-fuel ratio together with the air remaining in the cylinder can be obtained. The occurrence of problems such as formation and deterioration of combustion is prevented.

[0080]

According to the invention described in each of the claims, the opening and closing timing of the intake valve and the opening and closing timing of the exhaust valve are not simultaneously changed in the direction of increasing the overlap. The occurrence is prevented. In particular, when the load is rapidly reduced from a high load to a light load, the opening and closing timing of the intake valve and the opening and closing timing of the exhaust valve are changed so that there is no overlap at the same time. The combustion instability due to the rapid decrease of the temperature is suppressed.

In particular, when the opening / closing timing of the exhaust valve is changed from the first exhaust timing to the second exhaust timing in accordance with the increase of the load to a high load, the exhaust valve may be exhausted before the start of the change. The fuel injection timing of the fuel injection valve is changed so that the fuel is injected during a period in which the valve is closed and the intake valve is open, thereby preventing the fuel from flowing into the exhaust port.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the structure of the valve timing control device cut along a plane passing through a cam center axis.

FIG. 3 is a view of the device of FIG. 1 as viewed from an axial direction.

FIG. 4 is a view showing a structure of an oil control valve 90.

FIG. 5 is a cross-sectional view showing communication between the oil control valve 90 and an oil passage in the camshaft 50, taken along line 4-4 in FIG. 1;

FIG. 6 is a diagram illustrating a decrease in exhaust port pressure due to optimization of an exhaust pipe length.

FIG. 7 is a map showing a change in an amount of overlap with respect to an engine speed NE and a throttle opening THA.

FIG. 8 is a table showing phases of an exhaust cam and an intake cam with respect to each overlap amount.

FIGS. 9A and 9B are diagrams showing an opening period and an overlapping period of the exhaust valve and the intake valve when the overlap is large, medium, and no, and FIG. In the case (c), the overlap is large.

FIG. 10 is a flowchart of an overlap control routine.

FIG. 11 is a flowchart of a routine of overlap control.

FIG. 12 is a flowchart of an overlap control routine.

FIG. 13 shows the valve housing 20 of the valve characteristic control device 100 when the phase of the intake camshaft is most advanced.
2 shows the relative positional relationship between the motor and the rotor 40.

FIG. 14 shows the valve housing 2 of the valve characteristic control device 100 ′ when the phase of the exhaust camshaft is most retarded.
The relative positional relationship between 0 'and the rotor 40' is shown.

FIG. 15 is a flowchart of calculation of injection timing.

[Explanation of symbols]

2 ... intake pipe 3 ... surge tank 4 ... intake manifold 5 ... air cleaner 6 ... exhaust manifold 7 ... exhaust pipe 10 ... gear 20, 20 '... housing 22, 22' ... inner protrusion 30 ... side cover 40, 40 '... rotor 42, 42 '... vanes 50, 50' ... camshaft 70 ... cylinder head 80 ... cam cap 90 ... oil control valve 100, 100 '... valve characteristic control device 200 ... ECU 211 ... airflow meter 212 ... crank position sensor 213 ... cooling a water temperature sensor 214, 214 '... cam angle sensor 215 ... O ₂ sensor 251 ... electronic throttle 253 ... ignition plug

Claims (5)

[Claims] An operating load detecting means for detecting an operating load, a target valve opening / closing timing storing means for storing target opening / closing timing of an intake valve and an exhaust valve set according to the operating load, and an intake valve are set. An intake valve characteristic controller that adjusts the opening and closing timing of the intake valve so that it opens and closes at the target opening and closing timing, and an exhaust valve characteristic controller that adjusts the opening and closing timing of the exhaust valve so that the exhaust valve opens and closes at the set target opening and closing timing The target opening / closing timing stored in the target valve opening / closing timing storage means is the intake first opening / closing timing with the intake valve opening / closing timing being delayed with respect to the first stage light load, and the exhaust valve opening / closing timing. Is the first timing of the exhaust on the advancing side. The closing timing is the advanced intake second timing, the exhaust valve opening / closing timing is the advanced exhaust first timing, and the intake valve opening / closing timing is advanced for the third stage high load. At two timings, when the opening / closing timing of the exhaust valve is the second exhaust timing on the delay side and the load is increased by only one stage, only the opening / closing timing of either the intake valve or the exhaust valve is changed. Features internal combustion engine. 2. When the load is rapidly increased from a light load to a high load, the change of the opening / closing timing of the intake valve from the first intake timing to the second intake timing by the intake valve characteristic control device becomes the total change amount. 2. The internal combustion engine according to claim 1, wherein after a predetermined ratio has been reached, the exhaust valve characteristic control device starts changing the opening / closing timing of the exhaust valve from the first exhaust timing to the second exhaust timing. . 3. When the load is rapidly decreased from a high load to a light load, the intake valve characteristic control device changes the opening / closing timing of the intake valve from the second intake timing to the first intake timing, and the exhaust valve characteristic. 2. The internal combustion engine according to claim 1, wherein the control device simultaneously starts changing the opening / closing timing of the exhaust valve from the second exhaust timing to the first exhaust timing. 3. 4. When the load is reduced from a high load to a medium load, in addition to the change of the opening / closing timing of the exhaust valve from the second exhaust timing to the first exhaust timing by the exhaust valve characteristic control device, the characteristic of the intake valve is changed. The control device simultaneously changes the intake valve opening / closing timing from the intake second timing to the intake first timing, and then changes the intake valve opening / closing timing from the intake first timing to the intake second timing by the intake valve characteristic control device. The internal combustion engine according to claim 3, wherein: 5. When the opening / closing timing of the exhaust valve is changed from the first exhaust timing to the second exhaust timing as the load increases to a high load, the exhaust valve is closed and the intake valve is opened before the change is started. 2. The internal combustion engine according to claim 1, wherein the fuel injection timing of the fuel injection valve is changed so that the fuel is injected during the predetermined period.