JP2004092452A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine for changing the phase to correct the dispersion of average cylinder internal pressure of each bank to substantially equalize the internal pressure. <P>SOLUTION: This internal combustion engine comprises a first cam 2 for determining the lift quantity and opening timing of an intake valve; a second cam 2 for determining the lift quantity and opening timing of the intake valve, which has a lift quantity and working angle set smaller than the first cam; a plurality of banks having a variable valve gear 1 for switching the first cam to the second cam according to the load and rotating speed of the internal combustion engine to set the lift quantity and opening timing of the intake valve; a means 8 for detecting the cylinder internal pressure of each cylinder; a means 4 for calculating the average value of cylinder internal pressure of each bank; and a means 4 for correcting the opening timing to equalize the cylinder internal pressure average value of each bank. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an internal combustion engine.
[0002]
[Prior art]
Conventionally, two types of cams (an output cam suitable for exhibiting high output and an output cam and a lift Japanese Patent Application Laid-Open No. 8-260927 discloses a configuration in which a fuel consumption cam having a small amount and a small operating angle and suitable for improving fuel efficiency is provided, and these cams are switched according to the load and the rotation speed of the internal combustion engine. Such a variable valve mechanism can be applied to a V-type internal combustion engine.
[0003]
[Problems to be solved by the invention]
However, when a variable valve mechanism is applied to a V-type internal combustion engine, there is a problem of deviation of the central angle of each bank of the V-type internal combustion engine. For example, a deviation occurs in the central angle due to an assembly error of the internal combustion engine, an operation error of the continuous phase variable device, and the like, but the deviation amount is not a problem because the amount of intake air is large in the operation with the intake valve responding to the output cam. When operating with the intake valve that responds to the fuel consumption cam with a small operating angle, differences in the intake air amount between the left and right banks and imbalance in the residual gas rate between the left and right banks occur, resulting in poor drivability, low fuel efficiency, and low emissions. There is a problem that deterioration is caused.
[0004]
The present invention has been made in view of such a problem, and corrects variations in the average in-cylinder pressure of each bank due to a deviation of the center angle of the left and right banks during fuel economy cam operation, and adjusts the phases so as to be substantially the same. It is an object to provide an internal combustion engine for correction.
[0005]
[Means for Solving the Problems]
The present invention determines a lift amount of an intake valve and a valve opening period, switches between a first cam and a second cam having different lift amounts and operating angles, and switches between the first cam and the second cam. A plurality of banks each having a variable valve operating device for varying a valve period; a unit for detecting an in-cylinder pressure of each cylinder; a unit for calculating an average value of the in-cylinder pressure for each bank; and an in-cylinder pressure for each bank. Means for correcting the opening timing of the intake valve so that the average value is the same.
[0006]
【The invention's effect】
According to the present invention, in an internal combustion engine having a plurality of banks, since the phase of the intake valve is changed so that the average in-cylinder pressure of each bank is the same, imbalance in the intake air amount of each bank is suppressed, It is possible to suppress deterioration of fuel efficiency, drivability, and emission.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0008]
FIG. 1 is a schematic diagram of an internal combustion engine to which the present invention is applied. This V-type internal combustion engine includes a variable valve operating device 1. The variable valve operating device 1 controls an output cam (first cam) that emphasizes drivability and a fuel efficiency based on a cam 2 based on a rotational speed and a required load. And the intake valve 3 is opened and closed. Here, the operation angle (= opening period of the intake valve) of the output cam is set to 240 ° crank angle or less, and the fuel consumption cam is set to 180 ° crank angle or less.
[0009]
A control unit 4 composed of a microcomputer or the like for controlling the variable valve device 1 is installed. The control unit 4 includes an output of a sensor 5 for detecting an amount of depression of an accelerator pedal (hereinafter, referred to as APO), and , The output of the inhibitor switch 6 and the output of the rotation speed sensor 8 for detecting the rotation speed of the crankshaft 7 (= the rotation speed of the internal combustion engine). The control unit 4 calculates, for example, a fuel injection amount based on these input values, and controls an injector (not shown). Further, a cam and a phase to which the intake valve 3 responds are selected, and the lift amount, the valve opening period and the valve opening timing of the intake valve 3 are controlled.
[0010]
The variable valve apparatus 1 has, for example, the configuration of a variable valve described in Japanese Patent Application Laid-Open No. 8-260927, and the control unit 4 includes two solenoid valves (switching between a fuel efficiency cam and an output cam) and a variable phase. Above, three electromagnetic switching valves for changing the phase are provided in each bank, so that a total of three valves are controlled based on the input value. FIG. 2 shows a block diagram of the configuration of the control unit 4.
[0011]
The rotation speed from the rotation sensor 8, the APO from the sensor 5, and the in-cylinder pressure from the in-cylinder pressure detecting means are input to the control unit 4. Here, the detection of the in-cylinder pressure can be calculated based on the crank angular speed detected by the rotation speed sensor 8 using the technique disclosed in Japanese Patent Application Laid-Open No. 10-278585. Alternatively, the detection may be performed by installing a piezoelectric sensor in a washer portion of an ignition plug (not shown) desired in the combustion chamber of each cylinder. Further, a piezoelectric element may be installed in the cylinder as desired, and detection may be performed using this element.
[0012]
The engine rotation speed and the APO are output to a cam switching determination unit 4a and a continuously variable phase conversion angle calculation unit 4b that constitute the control unit 4. The in-cylinder pressure is output to the left and right bank average pressure and average pressure variation calculation unit 4c, and the average pressure and average pressure variation calculated by the calculation unit 4c are output to the continuously variable phase conversion angle calculation unit 4b.
[0013]
The continuously variable phase conversion angle calculation unit 4b calculates a phase conversion angle according to the engine speed, APO, average pressure and average pressure variation, and outputs the calculated angle to the continuously variable phase instruction unit 4e. The variable phase solenoid valve installed in each bank is controlled based on the phase conversion angle thus set.
[0014]
On the other hand, the cam switching determining section 4a determines whether or not cam switching is necessary according to the input value, and the switching solenoid instructing section 4d controls the cam switching solenoid valve based on the determination result.
[0015]
FIG. 3 shows an example of the difference between the characteristics of the fuel efficiency cam and the output cam. As is clear from the figure, the fuel efficiency cam is set to have a smaller valve lift amount and operating angle than the output cam. In addition, the lift center angle of the fuel efficiency cam is advanced with respect to the lift center angle of the output cam, thereby increasing the overlap between the intake valve and the exhaust valve to improve fuel efficiency. Further, the pumping loss can be reduced by making the phase variable, that is, by advancing the phase at the time of operation with the fuel efficiency cam, and the fuel efficiency can be further improved by operating the internal EGR.
[0016]
FIG. 4 is a diagram showing an example of an operation area of the fuel efficiency cam and the output cam.
[0017]
FIG. 5 is a flowchart for explaining the in-cylinder pressure correction control contents of the present invention. This control is executed by the control unit 4. In this flowchart, it is assumed that the in-cylinder pressure is detected for each cylinder.
[0018]
First, the cam currently used is checked in step 1, and if it is a fuel-saving cam, the process proceeds to step 2, and if it is an output cam, this determination is repeated. Here, the reason why the in-cylinder pressure correction control is limited to the fuel-efficient cam operation is that the output cam operation has a large amount of intake air supplied to the engine, so that the sensitivity to the phase change of the center angle of the cam is low, and the response is slow. Is not good and the effect is small. Further, if the in-cylinder pressure correction control is performed during the operation of the output cam, hunting or the like may occur, and the combustion state may be unstable. Therefore, during the output cam operation, the in-cylinder pressure correction is not performed, and the calculation load is reduced.
[0019]
In step 2, the in-cylinder pressure of each cylinder in each bank is detected to determine whether the pressure is within the allowable pressure. If the pressure is within the allowable pressure, the process proceeds to Step 3, and if the pressure is higher than the allowable pressure, the process proceeds to Step 4. Here, when the difference between the upper and lower limits of the in-cylinder pressure during one cycle of the in-cylinder pressure detecting means or the standard deviation of the detected pressure exceeds a predetermined value, it is determined that the variation is large, and the next step is performed. Correct the phase. Alternatively, the difference between the upper and lower limits may be divided by the average in-cylinder pressure of each bank and compared with another predetermined value. Since the phase is retarded when the in-cylinder pressure of each cylinder in each bank is not within the allowable pressure, the accuracy of in-cylinder pressure correction control can be improved.
[0020]
In step 4, the phase is retarded according to the difference between the detected value and the allowable pressure. The retard amount can be set based on a preset map or the like. Subsequently, it is determined whether or not the in-cylinder pressure is within the allowable pressure based on the phase corrected in step 5. If the determination is satisfied, the process proceeds to step 3, and if not, the process returns to step 4 and the phase correction is repeated.
[0021]
In step 3, the average in-cylinder pressure in each of the left and right banks is calculated, the difference is determined, and it is determined whether or not the difference is within a reference value. If it is within the reference value, the combustion state of each cylinder is determined to be stable, and the control is terminated. , The phase of the cam is corrected for retardation.
[0022]
By such control, the imbalance of the intake air amount between the left and right banks is suppressed, and the deterioration of fuel efficiency, the operability, and the emission can be suppressed.
[0023]
In the following step 7, it is determined once again whether or not the difference between the average in-cylinder pressures of the left and right banks is within the reference value. If the value is within the reference value, the combustion is considered stable, and the control is terminated. If the value is not within the reference value, the process returns to step 6, and the retard correction is repeated.
[0024]
The present invention is not limited to the above-described embodiments, and it is apparent that various changes can be made within the scope of the technical idea of the present invention.
[Brief description of the drawings]
FIG. 1 is a diagram showing a system configuration according to an embodiment of the present invention.
FIG. 2 is a block diagram illustrating a configuration of a control unit.
FIG. 3 is a diagram showing a difference in cam characteristics.
FIG. 4 is a diagram illustrating an example of an operation area of a fuel efficiency cam and an output cam.
FIG. 5 is a flowchart for explaining in-cylinder pressure correction control performed by a control unit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Variable valve apparatus 2 Cam 3 Intake valve 4 Control unit 5 APO sensor 6 Inhibitor switch 7 Crankshaft 8 Rotation speed sensor

Claims (6)

A first cam that determines a lift amount and a valve opening period of the intake valve;
A second cam that determines a lift amount and a valve opening period of the intake valve, and sets a lift amount and an operating angle smaller than the first cam;
A plurality of banks each provided with a variable valve operating device that switches between the first cam and the second cam according to a load and a rotation speed of the internal combustion engine to set a lift amount and a valve opening period of an intake valve;
Means for detecting the in-cylinder pressure of each cylinder;
Means for calculating an average value of the in-cylinder pressure for each bank,
Means for correcting the opening timing of the intake valve so that the in-cylinder pressure average value for each bank is the same,
Internal combustion engine equipped with. A first cam that determines a lift amount and a valve opening period of the intake valve;
A second cam that determines the lift amount and valve opening period of the intake valve, and sets the lift amount and the operating angle smaller than the first cam;
A plurality of banks each provided with a variable valve operating device that switches between the first cam and the second cam according to a load and a rotation speed of the internal combustion engine to set a lift amount and a valve opening period of an intake valve;
Means for detecting the in-cylinder pressure of each cylinder;
Means for detecting variation between cylinders of the detected in-cylinder pressure,
Means for correcting the variation of the in-cylinder pressure for each cylinder to a predetermined value or less,
Means for calculating an average value of the in-cylinder pressure for each bank,
Means for correcting the opening timing of the intake valve so that the in-cylinder pressure average value for each bank is the same,
Internal combustion engine equipped with. 3. The internal combustion engine according to claim 1, wherein the cylinder arrangement is V-shaped. 3. The internal combustion engine according to claim 1, wherein the operation of the first cam does not correct the opening timing of the intake valve. 4. The internal combustion engine according to claim 1 or 2, wherein the opening timing of the intake valve of the bank having the smaller in-cylinder pressure average value for each bank is retarded. Means for detecting the rotational speed of the crankshaft;
3. An internal combustion engine according to claim 1, further comprising means for calculating an average value of the in-cylinder pressure based on the detected rotation speed.

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