JP2003056374A - Variable valve system controller for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To unify suction efficiency between cylinders in an engine having a degraded characteristic of suction efficiency among the cylinders. SOLUTION: In a V-type 8-cylinder engine having a two-plane crank shaft arrangement in which four crank pins are arranged by a 90 deg. phase difference and positioned on two orthogonal planes, exhaust valve closing timing is advanced while intake valve opening timing is delayed in a cylinder, whose interval (crank shaft) from the just previous combustion cylinder is not 180 degrees, in setting operation areas (S1-S3) excepting idling and the like. In this way, a valve overlapping quantity is reduced, and consequently, a residual gas amount is reduced. Intake valve closing timing is corrected in the direction increasing an intake gas total amount for increasing a fresh air amount and respective correction quantities for increasing suction efficiency are computed, and then, control to the valve timing corrected with the respective correction values is carried out (S4-S6, S8).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for controlling intake / exhaust valves (variable valve actuation) of an engine, such as an electromagnetic drive type, which can arbitrarily control opening / closing timings, and more particularly to a combustion efficiency between cylinders by the device. Technology for equalizing

[0002]

2. Description of the Related Art As a V-type 8-cylinder engine, there is a crank arrangement called a 2-plane crankshaft. As shown in FIGS. 2 (A) to 2 (C), in this structure, four crank pins are arranged with a phase of 90 ° each, and they are located on two orthogonal planes.

The other is, as shown in FIGS. 2D to 2E, the crank arrangement for each bank is the same as that of the in-line 4-cylinder engine.
Since four crank pins are arranged with a phase of 180 ° each and are located on one plane, the crank arrangement is called a single plane crankshaft.
The crank arrangement of the above 2 plane crankshaft is
Because of the good balance of inertial force, this crank arrangement is exclusively used for passenger cars that emphasize riding comfort.

However, with this crank arrangement, the combustion order does not alternate between the left and right banks, and the combustion intervals within the same bank are unequal, so the intake and exhaust pulsations are effectively used for all cylinders. Difficult to do. Even if the pulsation effect (inertial supercharging) is set for two cylinders at 180 ° intervals, the effect cannot be obtained for the remaining two cylinders, and the output of the engine as a whole is sacrificed.

In order to effectively utilize the pulsation, a large layout of intake and exhaust manifolds extending over both banks is required, which is not realistic. Incidentally, JP-A-6-2292
No. 12 discloses that the deviation of the intake air amount for each bank is detected and the valve timing for each bank is corrected so as to eliminate the deviation of the intake air amount.
When adopted in a V-type 8-cylinder engine with a plain crankshaft, correction of valve timing for each bank cannot deal with variations in intake air amount that occur between cylinders in the same bank.

The present invention has been made in view of such a conventional problem. When the combustion intervals are unequal and the intake efficiency conditions between the cylinders are not equal, the intake air amount is equalized to improve the combustibility. An object of the present invention is to provide a variable valve operating control system for an engine that can eliminate variations.

[0007]

Therefore, in the invention according to claim 1, the valve characteristics of the intake and exhaust valves can be independently controlled for each cylinder, and one exhaust pipe is connected to the cylinder group. And, in an engine in which the combustion interval between the cylinders in the cylinder group is different, the cylinder group in which the combustion interval between the cylinders is different, and the intake valve of the cylinder whose intake efficiency is inferior to other cylinders or It is characterized in that the valve characteristic of at least one of the exhaust valves is changed so as to increase the suction efficiency.

According to the first aspect of the present invention, the valve characteristic of the cylinder having the poor intake efficiency is changed to increase the intake efficiency to be equal to that of the other cylinders, whereby the potential of the entire engine can be increased and the output performance, Fuel efficiency is improved.
In the invention according to claim 2, the engine is an 8-cylinder engine having a group of four cylinders in each bank, and four crankpins are arranged with a phase of 90 °. , 2 planes located on 2 orthogonal planes
It is characterized by the crank arrangement of the crankshaft.

According to the second aspect of the present invention, as described above, the crank arrangement of the two-plane crankshaft ensures a good balance of inertial forces,
It is possible to eliminate the variation in the intake air amount between the cylinders, which is a problem in the crank arrangement. Further, the invention according to claim 3 is characterized in that, in at least one cylinder group, the valve characteristics are changed between each cylinder having a combustion interval of 180 ° from the immediately preceding combustion cylinder and each cylinder other than that. To do.

According to the invention of claim 3, in the above 8-cylinder engine, the combustion intervals in the same bank are ideally equal intervals, that is, 180 °, and the interval with the pre-combustion cylinder is 1.
A cylinder having an angle of 80 ° is generally not easily affected by exhaust interference or the like. On the contrary, in the other cylinders, the intake efficiency is reduced due to the influence of exhaust interference or the like. Therefore, the intake efficiency of the entire engine can be increased by changing the valve characteristics by dividing into two groups.

Further, in the invention according to claim 4, in at least one cylinder group, the combustion interval from the immediately preceding combustion cylinder is 180.
It is characterized in that the valve characteristics are changed between each cylinder of which the combustion interval is 90 °, a cylinder of which the combustion interval is 90 °, and a cylinder of which the combustion interval is 270 °. According to the invention of claim 4, in the above-mentioned eight-cylinder engine, there are two cylinders having a combustion interval of 180 ° from the immediately preceding combustion cylinder for each bank, and the remaining cylinders have the same combustion interval of 90 °. Since the cylinder has a combustion interval of 270 °, the intake efficiency of the entire engine can be increased by changing the valve characteristics.

Further, the invention according to claim 5 is characterized in that, in at least one cylinder group, the exhaust valve closing timing of the cylinder having inferior intake efficiency is earlier than that of the other cylinders. According to the invention of claim 5, by making the exhaust valve closing timing of the cylinder having the poor suction efficiency earlier than that of the other cylinders,
The intake efficiency can be improved by reducing the valve overlap amount of the cylinder to reduce the residual gas amount and relatively increasing the fresh air amount.

The invention according to claim 6 is characterized in that, in at least one cylinder group, the intake valve opening timing of a cylinder having a poor intake efficiency is delayed as compared with other cylinders. According to the invention of claim 6, by delaying the intake valve opening timing of the cylinder having the poor intake efficiency as compared with the other cylinders,
The intake efficiency can be improved by reducing the valve overlap amount of the cylinder to reduce the residual gas amount and relatively increasing the fresh air amount.

The invention according to claim 7 is characterized in that, in at least one cylinder group, the intake valve closing timing of a cylinder having a poor intake efficiency is corrected so that the intake air amount increases. According to the invention of claim 7, the intake valve closing timing at which the total intake gas amount becomes maximum due to the intake inertia is at a position delayed by a predetermined amount after the bottom dead center. Therefore, the intake air amount (intake efficiency) can be increased by increasing the total intake gas amount by correcting the intake valve closing timing in the direction of approaching the time when the total intake gas amount becomes maximum.

Further, the invention according to claim 8 is to maintain the same valve characteristic between cylinders without changing the valve characteristic in a region where the intake inertia supercharging effect due to the pulsation of intake and exhaust is small. Characterize. According to the invention of claim 8, in a low load region such as idle, the original intake amount is small and the influence from other cylinders is small, so the pulsation effect of intake and exhaust is small, and the difference in residual gas when the valve characteristic is changed. The difference in combustion will increase. Therefore, in such a region, good performance is secured by maintaining the same valve characteristic between the cylinders.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. FIG. 1 illustrates a V-type 8-cylinder engine that employs a 2-plane crankshaft and has a combustion sequence as shown in FIG. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a system configuration diagram of an engine in the embodiment. In FIG. 1, V mounted on the vehicle
Air is drawn into each cylinder of the type 8 cylinder engine 1 through an air cleaner 2, an electronically controlled throttle chamber 3, an intake collector 4, an intake manifold 5, and an intake valve 6. The V-type 8-cylinder engine 1 is referred to as the above-mentioned two-plane crankshaft in which four crankpins are arranged at 90 ° phases as shown in FIGS. 2 (A) to (C). Has a crank arrangement that is

An electromagnetic fuel injection valve 7 for directly injecting fuel (gasoline) is provided in the combustion chamber of each cylinder, and the fuel and intake air injected from the fuel injection valve 7 cause a mixture in the combustion chamber. Is formed. The air-fuel mixture formed in the combustion chamber is ignited and burned by the spark plug 8. However, the engine 1 is not limited to the above direct injection gasoline engine, and may be an engine configured to inject fuel into the intake port.

Exhaust gas from the engine 1 is discharged into the atmosphere through an exhaust valve 9, an exhaust manifold 10, a catalyst 11 and a muffler 12. The exhaust manifold 10 has a structure in which one exhaust pipe 10A, 10B is connected to each bank (cylinder group), and these are joined on the downstream side. The opening and closing of the intake valve 6 and the exhaust valve 9 are electronically controlled by a valve driving device 13.

As sensors for detecting various states of the engine 1, an air flow meter 14 for detecting an intake air amount,
A throttle sensor 15 for detecting the throttle opening, a crank angle sensor 16 capable of outputting a reference signal at the reference crank angle of each cylinder and outputting a unit angle signal for each minute crank angle, and detecting the engine rotation speed based on the signal. A water temperature sensor 17 and the like for detecting the engine cooling water temperature are provided.

The detection signals from the various sensors are input to the control unit 18, which controls the fuel injection valve 7 based on these detection signals.
A fuel injection signal is output to control the fuel injection, an ignition signal is output to the spark plug 8 to perform ignition control, and a valve drive signal is output to the valve drive device 13 to intake valve 6 and exhaust gas. It controls the opening and closing of the valve 9.

Here, the hardware of the electromagnetic valve device including the intake valve 6 and the exhaust valve 9 and the valve drive device 13 for driving them will be described with reference to FIG. In FIG. 3, the exhaust valve 9 is attached to the cylinder head 21 in the same manner as the conventional one. That is, the stem 31 of the exhaust valve 9 is slidably inserted into the valve guide 22 provided in the cylinder head 21, and the stem 3
An upper seat 32 is attached to an upper end portion of the cylinder 1 via a valve cotter or the like, and the exhaust valve 9 is biased in the valve closing direction between the upper seat 32 and the lower seat on the cylinder head side (from a free length. A valve closing spring 33 (compressed by a predetermined amount) is provided.

When the exhaust valve 9 is fully closed and the armature is attracted by the valve-closing electromagnet 43, which will be described later, the stem 31 is separated from the upper end by a predetermined amount,
In other words, the movable shaft 40 of the valve drive device 13 is arranged coaxially with the stem 31 with a predetermined valve clearance. The valve drive device 13 is
A housing 41 made of a non-magnetic material, an armature 42 integrally provided on the movable shaft 40 and slidably housed in the housing 41, and a position facing the upper surface of the armature 42 so that the armature 42 can be magnetically attracted. In housing 42
A valve-closing electromagnet 43 fixedly disposed inside the valve body, and a valve-closing electromagnet 43 fixedly disposed inside the housing 41 at a position facing the lower surface of the armature 42 so that the exhaust valve 4 can be held open by magnetic attraction of the armature 42. An electromagnet 44 and a valve opening spring 45 for urging the armature 42 toward the valve opening direction of the exhaust valve 4.
And are included.

As shown in FIG. 4, when the valve closing electromagnet 43 and the valve opening electromagnet 44 are both demagnetized, the exhaust valve 9 is arranged in a half open position. When only the valve-closing electromagnet 43 is energized and excited, the armature 42 is magnetically attracted by the valve-closing electromagnet 43 in a direction to compress the valve-opening spring 45, while only the valve-opening electromagnet 44 is energized and excited from the half-open position. Then, the armature 42 is magnetically attracted by the valve opening electromagnet 44 in the direction in which the valve closing spring 33 is pressed and contracted to open the exhaust valve 9.

Although the opening / closing operation of the exhaust valve 9 has been described above, the intake valve 6 also operates in the same manner with a completely similar structure. Then, before starting, the intake valve 6 and the exhaust valve 9 are initialized from the half-open position to the open (fully open) position or the closed position, and then opened / closed according to the engine operating state. Opening / closing control is performed so that it is opened / closed at the time.

By the way, in the V-type 8-cylinder engine having the two-plane crankshaft in this embodiment, as described above, the combustion order does not alternate between the left and right banks, and the combustion intervals in the same bank are not uniform. (See Figure 5),
Intake inertial supercharging that effectively utilizes intake and exhaust pulsations cannot be performed, and the explosion pressure of each cylinder will vary. That is, the engine 1 can independently control the valve characteristics of the intake valve 6 and the exhaust valve 9 for each cylinder by the valve drive device 13, one exhaust pipe 10A, 10B is connected to each cylinder group, and The combustion intervals between the cylinders in the cylinder group are different.

Therefore, in the present invention, by changing the valve timing for the cylinder in which the residual gas increases and the combustion deteriorates, the residual gas amount of the cylinder is reduced or the intake fresh air amount is increased, so that By equalizing the combustion characteristics, the combustion efficiency of the entire engine is increased and the potential is improved. That is, in a group of cylinders having different combustion intervals between the cylinders, the valve characteristics of at least one of the intake valve and the exhaust valve of the cylinder whose intake efficiency is inferior to the other cylinders are changed to increase the intake efficiency. As a method of reducing the residual gas amount, there is a method of changing the valve overlap amount of the intake valve 6 and the exhaust valve 9 in a direction of reducing the valve overlap amount. Specifically, as shown in FIG. 6, the closing timing of the exhaust valve 9 (EV
This can be achieved by advancing C) or delaying the opening timing (IVO) of the intake valve 6 as shown in FIG. 7.

Further, as shown in FIG. 8, when the valve overlap center is originally set on the advance side larger than the top dead center, the closing timing (EVC) of the exhaust valve 9 and the opening timing of the intake valve 6 are set. Even if (IVO) is retarded by the same amount, the residual gas amount can be reduced while keeping the valve overlap amount the same. In addition, as a method of increasing the intake fresh air amount by increasing the total amount of intake gas, the closing timing of the intake valve 6 (IV
This can be achieved by changing C) so that the total amount of inhaled gas increases. As shown in FIG. 9, the intake valve closing timing IVC at which the intake air amount is maximized due to the intake inertia is at a position retarded by a predetermined amount after bottom dead center. Therefore, IV that maximizes the intake air amount
The IVC is corrected in the direction closer to CQmax. In a general engine, the IVC itself is set to the position where the air is most admitted, so that it is not feasible. However, as in the present embodiment, the intake valve is electromagnetically driven to control the intake air amount by IVC control. Then it is effective.

The influence of the exhaust interference and the like changes depending on the engine operating conditions (rotational speed, load, atmospheric pressure, etc.). Therefore, it is desirable that the presence / absence of the variation correction of the intake air amount and the correction amount thereof are changed according to the engine operating conditions. For example, during idle operation, there is almost no effect of exhaust gas interference, and conversely, there is a large effect of changes in the residual gas amount due to changes in the valve timing of each cylinder. Therefore, there is a possibility that the stability of rotation may be deteriorated, so it is desirable not to perform the correction itself.

Each embodiment will be described below with reference to the flowcharts shown in FIGS. In FIG. 10, in step 1, the engine operating region (rotational speed, load, etc.) is detected based on detection signals from various sensors. In step 2, it is determined whether or not the detected current engine operating region is a setting region in which the variation of the intake air amount is large and the variation correction is performed. Specifically, the medium / high load region excluding the low load region such as the idle is set as the setting region for correcting the intake air amount.

If it is determined in step 2 that the region is the set region, the process proceeds to step 3 and the cylinder whose intake air amount is to be corrected is determined. Specifically, when the interval (crank angle) from the cylinder that was in the previous combustion stroke in the same bank is 180 °, the exhaust pulsation effect is obtained, so the intake efficiency is high.
When the angle is 0 ° or 270 °, exhaust interference occurs, the exhaust pulsation effect cannot be obtained, the intake efficiency decreases, and the intake air amount needs to be increased and corrected. Referring to FIG. 5, since the seventh cylinder and fifth cylinder in the left bank and the eighth cylinder and fourth cylinder in the right bank are 180 ° apart from the pre-combustion cylinder, intake air amount correction is not performed. Since the first cylinder and the third cylinder in the left bank and the sixth cylinder and the second cylinder in the right bank have an interval of 270 ° or 90 ° from the pre-combustion cylinder, they are determined as cylinders for which the intake air amount is corrected.

In step 4, for the cylinder whose intake air amount is to be corrected, a correction amount for correcting the closing timing EVC of the exhaust valve 9 is calculated based on the engine operating conditions. Step 5
Then, similarly, a correction amount for correcting the opening timing IVO of the intake valve 6 is calculated. In step 6, a correction amount for similarly correcting the closing timing IVC of the intake valve 6 to IVCQmax that maximizes the intake air amount is calculated.

Here, the correction amount in steps 4 to 6 is the reduction amount of the intake air amount with respect to the cylinder whose interval from the pre-combustion cylinder is 180 ° based on the engine operating conditions.
As a correction amount for correcting the amount of residual gas by advancing EVC and delaying IVO to reduce the valve overlap amount so that it can be corrected, and increasing the total intake gas amount by approaching IVCQmax. calculate.

If it is determined in step 2 that the setting range is not for correcting the variation of the intake air amount, step 7
Then, the correction amount of the valve timing is set to 0 and the correction is prohibited. In step 8, the valve timing signals corrected by the respective correction amounts calculated as described above and set are output to control the valve timings of the intake valve 6 and the exhaust valve 9.

FIG. 11 shows a flow chart of the second embodiment in which only EVC and IVO are corrected and IVC is not corrected. With this, EVC hastened I
Not only is VO delayed to reduce the valve overlap amount, but as shown in FIG. 8, EVC and IVO may be retarded by equal amounts while the valve overlap amount is kept constant.

In the flowchart of the third embodiment shown in FIG. 12, only the EVC is advanced and corrected, and the fourth embodiment shown in FIG.
In the flowchart of this embodiment, only IVO is retarded, and in the flowchart of the fourth embodiment shown in FIG. 14, only IVC is corrected so as to approach IVCQmax.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of an engine according to an embodiment.

FIG. 2 is a cross-sectional view showing a configuration of the electromagnetic valve device according to the embodiment when the intake / exhaust valve is closed.

FIG. 3 is a cross-sectional view showing the configuration of the solenoid valve device when the exhaust valve is open.

FIG. 4 is a diagram showing the schematic configuration and operation of a V-type 8-cylinder engine having a two-plane crankshaft, in comparison with the operation of a V-type 8-cylinder engine having a single-plane crankshaft.

FIG. 5 is a diagram for explaining a combustion stroke sequence of a V-type 8-cylinder engine having a two-plane crankshaft.

FIG. 6 is a diagram showing a method of advancing the closing timing of the exhaust valve to reduce the residual gas amount.

FIG. 7 is a diagram showing a method of delaying the opening timing of the intake valve to reduce the residual gas amount.

FIG. 8 is a diagram showing a method of delaying the closing timing of the exhaust valve and the opening timing of the intake valve to reduce the residual gas amount.

FIG. 9 is a diagram showing a method of increasing the intake air amount by correcting the intake valve closing timing to a direction that maximizes the total intake gas amount.

FIG. 10 is a flowchart showing a control routine of the first embodiment.

FIG. 11 is a flowchart showing a control routine of the second embodiment.

FIG. 12 is a flowchart showing a control routine of the third embodiment.

FIG. 13 is a flowchart showing a control routine of a fourth embodiment.

FIG. 14 is a flowchart showing a control routine of the fifth embodiment.

[Explanation of symbols]

1 V type 8 cylinder engine 6 intake valve 9 Exhaust valve 13 Valve drive 14 Air flow meter 16 crank angle sensor 18 control unit

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3G018 AA07 AB16 BA31 CA12 EA31                       EA32 EA35 FA09 GA00 GA06                       GA07 GA32                 3G092 AA01 AA06 AA11 AA15 AB02                       BA01 BA02 BA04 DA01 DA02                       DA03 DA07 DA12 EA03 EA04                       FA00 FA01 FA02 FA15 FA48                       HA01Z HA06Z HE01Z HE03Z                       HE04Z HE08Z

Claims (8)

[Claims] 1. A valve characteristic of an intake / exhaust valve can be independently controlled for each cylinder, one exhaust pipe is connected to a cylinder group, and combustion intervals between the cylinders in the cylinder group are different. In a cylinder group in which the combustion intervals between the cylinders are different, the valve characteristics of at least one of an intake valve and an exhaust valve of a cylinder whose intake efficiency is inferior to those of other cylinders are set to increase the intake efficiency. A variable valve control device for an engine, which is characterized by changing to. 2. The engine is an 8-cylinder engine having a cylinder group of 4 cylinders in each bank, and 4 crankpins are arranged in phases of 90 ° each to form two orthogonal planes. 2. The variable valve operating system for an engine according to claim 1, wherein the crank arrangement is a two-plane crankshaft located above. 3. The valve characteristic of at least one cylinder group, wherein the valve characteristic is changed between each cylinder having a combustion interval of 180 ° from the immediately preceding combustion cylinder and each cylinder other than that. A variable valve control device for the engine described. 4. A valve comprising at least one cylinder group, each cylinder having a combustion interval of 180 ° from the immediately preceding combustion cylinder, a cylinder having a combustion interval of 90 °, and a cylinder having a combustion interval of 270 °. 3. The characteristic is changed.
Alternatively, the variable valve operating system for the engine according to claim 3. 5. The exhaust valve closing timing of a cylinder having inferior intake efficiency in at least one cylinder group is set to be earlier than that of the other cylinders. A variable valve operating system for an engine according to. 6. The intake valve opening timing of a cylinder having inferior intake efficiency in at least one cylinder group is delayed as compared with other cylinders. A variable valve operating system for an engine according to. 7. The method according to claim 1, wherein at least one cylinder group corrects an intake valve closing timing of a cylinder having a poor intake efficiency so as to increase an intake air amount. A variable valve control system for an engine according to item 3. 8. The same valve characteristic is maintained between cylinders without changing the valve characteristic in a region where the effect of intake / inertial supercharging due to intake / exhaust pulsation is small. Item 8. A variable valve operating system for an engine according to any one of items 7.