JP3801783B2 - Control device for idle cylinder engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for a cylinderless engine that can be switched between an all-cylinder operation in which all cylinders are operated and a cylinder-inactive operation in which some cylinders are deactivated.
[0002]
[Prior art]
Conventionally, this kind of cylinder-less engine has valve switching means for switching the intake / exhaust valves of some cylinders between a drive state and a drive stop state. The cylinders are deactivated. (See JP-A-8-74545)
[0003]
[Problems to be solved by the invention]
During idle cylinder operation, the pressure difference between the combustion chamber pressure of the idle cylinder and the crankcase pressure increases during the stroke corresponding to the intake stroke and explosion stroke during all cylinder operation, and oil in the crank chamber is sucked into the combustion chamber. In other words, so-called oil rising occurs. Then, the amount of oil in the combustion chamber of the deactivated cylinder increases with the continuation of the idle cylinder operation, and when the cylinder is restored from the idle cylinder operation to the all cylinder operation, the oil in the combustion chamber is discharged and exhaust emission deteriorates.
[0004]
In view of the above, it is an object of the present invention to provide a control device that can prevent deterioration of exhaust emission when all cylinders are returned to operation due to oil rising in a deactivated cylinder.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the present invention switches between all-cylinder operation in which all cylinders are operated and cylinder-inactive operation in which driving of intake and exhaust valves of some cylinders is stopped and some cylinders are deactivated. In a control system for a closed cylinder engine, a predicting unit that predicts the amount of oil accumulated in the combustion chambers of some of the cylinders during the idle cylinder operation, and a predicted amount by the prediction unit reaches a predetermined value. Then, temporary return means for temporarily returning to all-cylinder operation, and predetermined value setting means for setting the predetermined value low in order to prevent an increase in oil in the deactivated cylinder as the engine temperature decreases. I have.
[0006]
According to the present invention, when the amount of oil accumulated in the combustion chamber of the idle cylinder reaches a predetermined value after the oil has risen, the idle cylinder operation is temporarily returned to the all cylinder operation. Here, the predetermined amount is set so that the amount of oil accumulated in the combustion chamber when the oil reaches the idle cylinder is very small and can be temporarily returned to the all-cylinder operation while the oil can be burned well. If this is the case, exhaust emissions will not deteriorate during temporary all-cylinder operation. In particular, during the temporary all-cylinder operation, if the air-fuel ratio of the intake air mixture to the some cylinders that are the idle cylinders is made leaner than the air-fuel ratio of the intake air mixture to the other cylinders, the oil combustibility is improved. The exhaust emission can be effectively prevented from deteriorating. In this way, since the oil in the combustion chamber of the idle cylinder can be burned at any time during the idle cylinder operation, when returning to the all cylinder operation by the transition from the idle cylinder operation area to the all cylinder operation area, Exhaust emissions will not deteriorate due to oil discharge from the combustion chamber. Further, if the cylinder is temporarily returned to the full cylinder operation during the idle cylinder operation, the oil rise does not occur during that period, and the oil consumption due to the oil rise decreases compared to the case where the idle cylinder operation is continued.
[0007]
As the predicting means, it is possible to use a timer for measuring the elapsed time during the cylinder resting operation, and to temporarily return to the all cylinder operation when the elapsed time reaches the set time which is the predetermined value. The amount of oil accumulated by the engine is almost proportional to the number of engine revolutions. Therefore, the counting means that counts how many times the engine has rotated during idle cylinder operation constitutes a prediction means, and the accumulated oil amount is predicted by the count number of the counting means. However, the prediction accuracy is high. In this case, temporary return to all-cylinder operation is performed when the count by the counting means reaches a predetermined value. When using a timer, it is desirable to change the set time according to the operating state of the engine.
[0008]
By the way, when the engine temperature is lowered, the clearance between the inner wall surface of the cylinder and the piston is increased, and the oil rises easily. Here, if the predetermined value is set lower as the temperature becomes lower in accordance with the engine temperature, the operation is temporarily returned to the all-cylinder operation at an early time when the temperature is low, and the amount of oil in the combustion chamber of the idle cylinder is prevented from increasing at a low temperature. Can be advantageous.
[0009]
In the embodiment described later, the processing corresponding to the counting means is processing in steps S5 and S6 in FIG. 2, and the temporary returning means is processing in steps S7 and S8 in FIG. Yes, CT1 corresponds to the count number, and CTNML corresponds to the predetermined value.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
1, first and shows a V-type 6-cylinder engine provided with respective three cylinders 2 Bank 1 _1, 1 ₂ of the second pair, the common intake in both the banks 1 _1, 1 ₂ A manifold 3 and separate exhaust manifolds 4 ₁ and 4 ₂ for the first bank 1 ₁ and the second bank 1 ₂ are provided, a throttle valve 5 is provided upstream of the intake manifold 3, and an intake manifold is provided. A fuel injection valve 6 is provided at each branch portion connected to each cylinder 2 downstream of the cylinder 3 so that fuel is supplied from each fuel injection valve 6 to each cylinder 2.
[0011]
The first bank 1 _1, the valve switching means for switching the intake and exhaust valves of the first bank 1 ₁ of the cylinder 2 to the drive stopped state and the driving state (not shown) is provided, the valve switching means by the controller 7 stops the driving of the intake and exhaust valves controlled by the first bank 1 ₁ cylinder 2, by stopping the fuel injection from the first bank 1 ₁ of the fuel injection valves 6, both the banks 1 _1, 1 the _second cylinder 2 from all cylinders operation to run all have to switch to cylinder deactivation operation to pause the first bank 1 ₁ of cylinder 2.
[0012]
FIG. 2 shows a control program executed by the controller 7 when the cylinder is closed. This control program is executed at regular time intervals. First, in step S1, it is determined whether or not the idle cylinder satisfaction flag FST is set to 1. Can pause the first bank 1 ₁ of the cylinder 2, when stable operation in the operation of only the cylinders 2 of the second bank 1 ₂ can be maintained, specifically, the engine rotational speed NE is low and medium speed region (e.g. When three conditions are satisfied: 1500 rpm <NE <3500 rpm), vehicle speed V is equal to or higher than the start completion speed (eg, V> 15 km / h), and throttle opening TH is low (eg, 0.5 ° <TH <20 °). And FST is set to 1 when the above three conditions are satisfied by the background processing. Note that by a process in a main routine (not shown), the cylinder resting operation is performed when FST = 1, and the all cylinder operation is performed when FST = 0.
[0013]
If FST ≠ 1, the temporary return flag FNML, the cylinder rest rotation counter value CT1, and the all cylinder rotation counter value CT2 are each reset to 0 in step S2, and one process is completed.
[0014]
If FST = 1, it is determined whether or not FNML is set to 1 in step S3. Since FNML = 0 at the beginning of switching to the idle cylinder operation, the process proceeds from step S3 to step S4, and a table search is performed for an all-cylinder return determination value CTNML corresponding to the engine temperature, for example, the engine coolant temperature TW. CTNML is set so as to decrease as TW becomes lower in temperature.
[0015]
Next, the process proceeds to step S5, where a table representing the number of engine revolutions #CT within the execution time interval of the control program as a parameter of the engine speed NE is retrieved, and the previous time of the control program based on the current NE is searched. The number of rotations #CT of the engine that has rotated from the time of execution until now is obtained. Next, in step S6, CT1 is set to a value obtained by adding #CT to the previous value. Thus, CT1 represents the total number of revolutions of the engine since the start of cylinder resting operation.
[0016]
Next, in step S7, it is determined whether or not CT1 has reached CTNML. When CT1 ≧ CTNML, the process proceeds to step S8, and all cylinders that resume driving the intake and exhaust valves of the cylinder 2 of the first bank are resumed. Perform return control to operation. Next, it is determined whether the return control in step S9 has been completed, the process proceeds to step S10 when completed, the fuel supply to the first bank 1 ₁ of the cylinder 2, the first bank 1 ₁ cylinder 2 so that the air-fuel ratio of the intake mixture to the cylinder 2 becomes leaner than the air-fuel ratio of the intake mixture to the cylinder ₂ of the second bank 12, and FNML is set to 1 in step S 11. Reset CT1 to zero.
[0017]
Next time, it is determined that FNML = 1 in step S3, and the process proceeds to step S12. Based on the current engine speed NE, the number of rotations #CT of the engine that has rotated from the previous execution of the control program to the present is tabled. Search is performed, and CT2 is set to a value obtained by adding #CT to the previous value in step S13. Thus, CT2 represents the total number of rotations of the engine after returning to the all-cylinder operation. Next, in step S14, it is determined whether or not CT2 has reached a predetermined cylinder deactivation resumption determination value CTST. When CT2 ≧ CTST, the process proceeds to step S15, and the intake and exhaust of the cylinder 2 in the first bank 1 is performed. Pause control for stopping the valve drive and stopping the fuel supply to the cylinder 2 is executed. Next, it is determined in step S16 whether or not the suspension control is completed. When the control is completed, FNML is reset to 0 and CT2 is reset to 0 in step S17.
[0018]
Thus, during cylinder resting operation, every time the engine rotates the same number as CTNML, it temporarily returns to all cylinder operation while it rotates the same number as CTST. Here, CTNML, the oil amount accumulated in the first bank 1 ₁ of the cylinder 2 a combustion chamber by the oil up in the cylinder deactivation operation is, values such as within the range that can be favorably burned oil (e.g. 2000-4000 rotation ) intended to be set in, it until the accumulated oil in the first bank 1 ₁ of the cylinder 2 a combustion chamber by the return to the full-cylinder operation is well burned. Thus also in this embodiment, when a temporary full-cylinder operation, since the air-fuel mixture sucked into the cylinder 2 of the first bank 1 ₁ is lean, the air-fuel ratio becomes rich in the combustion chamber of the oil However, the combustibility is maintained well, and the exhaust emission is reliably prevented from deteriorating. Further, when the engine temperature is lowered, the clearance between the cylinder inner wall and the piston is increased, and the oil rises easily. However, in this embodiment, CTNML is set to become lower as the temperature becomes lower. Even at low temperatures, the entire cylinder operation can be temporarily restored before the amount of oil in the combustion chamber exceeds the appropriate range, and exhaust emission does not deteriorate. In this way, in order to burn oil at any time during the idle cylinder operation, a large amount of oil is discharged from the cylinder 2 of the first bank 1 when the FST is reset to 0 and switched from the idle cylinder operation to the all cylinder operation. As a result, exhaust emissions do not deteriorate. Incidentally, CTST is set to required value sufficient to burn the first bank 1 ₁ of all the cylinders 2 of the combustion chamber of the oil (e.g., 5 to 10 rotations).
[0019]
Although the V-type six-cylinder engine has been described above, the present invention can be similarly applied to a case where some of the cylinders are deactivated in an in-line multi-cylinder engine.
[0020]
【The invention's effect】
As apparent from the above description, according to the present invention, it is possible to prevent the exhaust emission from deteriorating when all cylinders are returned to operation due to the oil rising in the idle cylinder, and further contribute to the reduction of oil consumption due to the oil rising.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of an engine to which the present invention is applied. FIG. 2 is a flowchart showing a control program during cylinder idle operation.
1 ₁ 1st bank (bankless side bank) 1 ₂ 2nd bank 2 cylinder 7 controller CT1 Resting cylinder rotation counter value (count)
CTNML All cylinder return judgment value (predetermined value)

Claims (2)

In a control apparatus for a cylinder-cylinder engine that can be switched between all-cylinder operation for operating all cylinders and cylinder-cylinder operation for stopping drive of intake and exhaust valves of some cylinders to deactivate some cylinders. ,
Predicting means for predicting the amount of oil accumulated in the combustion chambers of some of the cylinders during the idle cylinder operation,
Temporary return means for temporarily returning to all-cylinder operation when the predicted amount by the prediction means reaches a predetermined value;
A predetermined value setting means for setting the predetermined value low in order to prevent an increase in oil in the idle cylinder as the engine temperature becomes lower;
A control device for a cylinderless engine, comprising: When said temporary full-cylinder operation, according to claim 1, characterized in that the lean of the air-fuel ratio of the intake mixture of an air-fuel ratio of the intake mixture of the to part of the cylinders to other cylinders Control device for idle cylinder engine.

Images