JP2000080936A - Cylinder intake air amount detection device for variable valve engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect the quantity of cylinder suction air quantity (in-cylinder new gas quantity) without using any airflow meter in a variable valve system engine provided with the intake and exhaust valves of solenoid driving systems to control the quantity of suction air by controlling the closing time of the intake valve. SOLUTION: A cylinder capacity at the closing time of an exhaust valve is calculated (S2 to S4), an exhaust density is calculated based on an engine running condition (S5), and an in-cylinder remaining gas quantity is calculated based on the cylinder capacity at the closing time of the exhaust valve and the exhaust density (S6). On the other hand, a cylinder capacity at the closing time of an intake valve is calculated (S1, S7 and S8), an in-cylinder gas density is calculated based on an intake pressure and an intake temperature (S9, and S10), and an in-cylinder total gas quantity is calculated based on the cylinder capacity at the closing time of the intake valve and the in-cylinder gas density (S11). Then, an in-cylinder remaining gas quantity is subtracted from the in- cylinder total gas quantity, and an in-cylinder new gas quantity is calculated (S12).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve having an intake valve and an exhaust valve of a variable valve type capable of arbitrarily controlling opening and closing timing, and controlling a closing timing of the intake valve to control an intake air amount. The present invention relates to a device for detecting a cylinder intake air amount (new air amount in a cylinder) of an engine.

[0002]

2. Description of the Related Art As a conventional cylinder intake air amount detecting device for a variable valve engine, as described in Japanese Patent Application Laid-Open No. 9-303242, an intake air amount is detected by an air flow meter in an intake passage. In some cases, the average value of the intake air amount during the intake valve opening timing and the intake valve closing timing, or the intake air amount at an intermediate time point during the intake valve opening period, is used as the cylinder intake air amount (representative value of the intake air amount).

[0003]

However, such a cylinder intake air amount detecting device requires an air flow meter, and closes the intake valve when the cylinder intake air flow rate is large by a variable valve operating mechanism. Equal,
When the intake air flow rate changes suddenly, an error occurs in the output value of the air flow meter, and there is a problem that the cylinder intake air amount cannot be accurately detected.

There is also a method of calculating the cylinder intake air amount from the operating conditions of the engine and the intake pipe pressure (and the intake air temperature). In a variable valve engine, the intake valve closing timing at the same intake pipe pressure is used. Since the cylinder volumes of the cylinders differ greatly, the amount of cylinder intake air fluctuates and cannot be accurately detected. SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional problems, and an air flow meter is provided in a variable valve engine that includes a variable valve type intake valve and an exhaust valve and controls an intake air amount by controlling a closing timing of the intake valve. It is an object of the present invention to accurately detect a cylinder intake air amount (cylinder fresh air amount) without using a cylinder.

[0005]

For this purpose, the invention according to claim 1 is configured as shown in FIG. That is, an intake valve closing cylinder volume calculating means for calculating the cylinder volume of the intake valve closing timing, an in-cylinder gas density calculating means for calculating the in-cylinder gas density of the intake valve closing timing, Means for calculating a total gas amount in the cylinder from the cylinder volume and the gas density in the cylinder.

Further, an exhaust valve closing cylinder volume calculating means for calculating the cylinder volume at the time of closing the exhaust valve, an exhaust density calculating means for calculating the exhaust density, and the cylinder volume and the exhaust density at the closing timing of the exhaust valve are used. And a cylinder residual gas amount calculation means for calculating the cylinder residual gas amount. Then, subtract the remaining gas amount in the cylinder from the total gas amount in the cylinder,
An in-cylinder fresh air amount calculating means for calculating an in-cylinder fresh air amount is provided.

The invention according to claim 2 is characterized in that the in-cylinder gas density calculating means calculates the in-cylinder gas density based on the intake pressure when the intake valve is closed. The invention according to claim 3 is characterized in that the in-cylinder gas density calculation means calculates the in-cylinder gas density based on the intake pressure and the intake temperature when the intake valve is closed.

According to a fourth aspect of the present invention, the exhaust density calculating means calculates the exhaust density based on the engine speed and the load. The invention according to claim 5 is characterized in that the variable valve type intake valve and the exhaust valve are electromagnetically driven.

[0009]

According to the first aspect of the present invention, the total gas amount in the cylinder is calculated based on the cylinder volume at the time of closing the intake valve, while the total amount of gas in the cylinder is calculated based on the cylinder volume at the time of closing the exhaust valve. By calculating the remaining gas amount in the cylinder and subtracting the remaining gas amount in the cylinder from the total gas amount in the cylinder to calculate the new air amount in the cylinder, the cylinder intake air amount (new air amount in the cylinder) is accurately obtained. The effect that it can be obtained is obtained.

According to the second aspect of the present invention, the gas density in the cylinder for accurately obtaining the total gas amount in the cylinder is determined by:
It can be accurately calculated based on the intake pressure at the time of closing the intake valve. According to the third aspect of the present invention, the gas density in the cylinder for accurately obtaining the total gas amount in the cylinder can be calculated more accurately based on the intake pressure and the intake temperature when the intake valve is closed.

According to the fourth aspect of the invention, the exhaust gas density for accurately obtaining the residual gas amount in the cylinder can be accurately estimated based on the engine speed and the load. According to the invention of claim 5, controllability is improved by using the electromagnetically driven intake and exhaust valves.

[0012]

Embodiments of the present invention will be described below. FIG. 2 is a system diagram of a variable valve engine showing one embodiment of the present invention. A combustion chamber 3 defined by a piston 2 of each cylinder of the engine 1 is provided with an electromagnetically driven intake valve 5 and an exhaust valve 6 so as to surround an ignition plug 4. 7 is an intake passage, and 8 is an exhaust passage.

FIG. 3 shows a basic structure of an electromagnetic drive device (variable valve device) for the intake valve 5 and the exhaust valve 6. A plate-like mover 22 is attached to a valve shaft 21 of the valve body 20, and the mover 22 is biased to a neutral position by springs 23 and 24. The valve opening electromagnetic coil 25 is disposed below the movable element 22, and the valve closing electromagnetic coil 26 is disposed above the movable element 22.

Accordingly, when the valve is opened, the power supply to the upper valve closing electromagnetic coil 26 is stopped, and then the current is supplied to the lower valve opening electromagnetic coil 25 to attract the movable element 22 to the lower side. As a result, the valve body 20 is lifted to open the valve. vice versa,
When the valve is closed, the energization of the lower valve opening electromagnetic coil 25 is stopped, and then the upper valve closing electromagnetic coil 26 is energized to attract the movable element 22 to the upper side.
Is seated on the seat and the valve is closed.

Returning to FIG. 2, an electromagnetic fuel injection valve 9 is provided in the intake passage 7 at an intake port for each cylinder. Here, the operation of the intake valve 5, the exhaust valve 6, the fuel injection valve 9, and the ignition plug 4 is controlled by the control unit 10
The control unit 10 includes:
A crank angle sensor 1 that outputs a crank angle signal in synchronization with the engine rotation and thereby detects the engine rotation speed
1, an accelerator pedal sensor 12 for detecting an accelerator opening (accelerator pedal depression amount), an intake pressure sensor 13 for detecting an intake pressure in the intake passage 7, an intake temperature sensor 14 for detecting an intake temperature in the intake passage 7, and the like. , A signal is input.

In the engine 1, non-throttle operation is performed by controlling the closing timing of the electromagnetically driven intake valve 5 (early closing control) to control the amount of intake air for the purpose of improving fuel efficiency by reducing pump loss. Do. That is, the opening timing (IVO) of the intake valve 5 is a fixed timing near the top dead center (TDC), and the closing timing (IV
C) is determined by the engine operating conditions.

The opening timing (EVO) and closing timing (EVC) of the exhaust valve 6 are controlled so as to be the timing having the highest thermal efficiency. The fuel injection amount by the fuel injection valve 9 is controlled based on a cylinder intake air amount (new cylinder air amount) detected by a cylinder intake air amount detection routine of FIG. I do.

The ignition timing of the ignition plug 4 is controlled to the MBT or knock limit based on the engine operating conditions. FIG. 4 is a flowchart of a cylinder intake air amount detection routine, which is executed at predetermined time intervals. In step 1 (referred to as S1 in the figure, the same applies hereinafter), it is determined whether or not it is the intake valve closing timing.
It is determined whether or not it is the closing time of the exhaust valve. If it is not the closing time of the exhaust valve, this routine ends.

If it is time to close the exhaust valve, steps 3-6
Execute In step 3, the crank angle at that time is measured. In step 4, the cylinder volume at the closing timing of the exhaust valve is calculated from the crank angle at the closing timing of the exhaust valve by referring to a predetermined table. This part corresponds to the cylinder volume calculation means when the exhaust valve is closed.

In step 5, the exhaust density is calculated from the engine speed and the load (the target torque or the basic fuel injection amount based on the accelerator opening) with reference to a predetermined map such as that shown in FIG. . This portion corresponds to the exhaust density calculating means. In Step 6, as shown in the following equation,
The residual gas amount in the cylinder is calculated from the cylinder volume at the time of closing the exhaust valve and the exhaust gas density.

Cylinder residual gas amount = cylinder volume at closing timing of exhaust valve × exhaust density This portion corresponds to cylinder residual gas amount calculating means. On the other hand, in the case of the closing timing of the intake valve, Step 7 to Step 1
Execute Step 2. In step 7, the crank angle at that time is measured. In step 8, the cylinder volume at the closing timing of the intake valve is calculated from the crank angle at the closing timing of the intake valve by referring to a predetermined table. This portion corresponds to cylinder volume calculation means when the intake valve is closed.

In step 9, the intake pressure and the intake temperature at the closing timing of the intake valve are measured. In step 10, the in-cylinder gas density at the intake valve closing timing is calculated based on the measured intake pressure and intake temperature of the intake valve closing timing as in the following equation. In-cylinder gas density at intake valve closing timing = intake pressure / intake temperature / gas constant This portion corresponds to the in-cylinder gas density calculation means.

In step 11, the total gas amount in the cylinder is calculated from the cylinder volume when the intake valve is closed and the gas density in the cylinder as in the following equation. Total gas amount in cylinder = cylinder volume when intake valve closes x
Cylinder gas density This portion corresponds to the cylinder total gas amount calculation means. Finally, in step 12, as shown in the following equation, step 11
Subtract the remaining gas amount in the cylinder obtained in step 6 from the total gas amount in the cylinder obtained in step (1) to obtain the new air amount in the cylinder.

New air volume in cylinder = Total gas volume in cylinder-
Cylinder residual gas amount This portion corresponds to the cylinder fresh air amount calculation means. By such a method, the cylinder fresh air amount, that is, the cylinder intake air amount can be accurately obtained. In addition, when a throttle valve is used in combination, the gas density in the cylinder that changes in accordance with the intake pressure is taken into consideration, so that it can be handled. In this case, it is more preferable to provide an atmospheric pressure sensor separately from the intake pressure sensor, and to correct the gas density in the cylinder to a higher side when the atmospheric pressure is high.

In this embodiment, it is assumed that there is no overlap between the exhaust valve and the intake valve. However, if there is an overlap, the correction may be made according to the amount of overlap. Further, although the electromagnetically driven type is used as the variable valve operating device, a hydraulically driven type may be used.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing a configuration of the present invention.

FIG. 2 is a system diagram of a variable valve engine showing one embodiment of the present invention.

FIG. 3 is a basic structural diagram of an electromagnetic drive device of the intake and exhaust valves.

FIG. 4 is a flowchart of a cylinder intake air amount detection routine.

FIG. 5 is a diagram showing an exhaust density calculation map;

[Explanation of symbols]

 Reference Signs List 1 engine 2 piston 3 combustion chamber 4 ignition plug 5 electromagnetically driven intake valve 6 electromagnetically driven exhaust valve 7 intake passage 8 exhaust passage 9 fuel injection valve 10 control unit 11 crank angle sensor 12 accelerator pedal sensor 13 intake pressure sensor 14 Intake air temperature sensor

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Takahiko Hirasawa 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa F-term (reference) in Nissan Motor Co., Ltd. 3G084 BA23 DA04 FA00 FA01 FA02 FA07 FA18 FA33 3G092 AA11 BA01 DA01 DA02 DA07 DA12 DD03 DG02 DG09 FA06 HA01X HA01Z HA04Z HA05Z HA11Z HA13X HA13Z HD00Z HE01Z 3G301 HA01 HA19 JA20 LA07 LC01 PA01A PA01Z PA07Z PA10Z PA17Z PD00Z PE01Z PE10A PE10Z

Claims (5)

[Claims] In a variable valve engine having a variable valve type intake valve and an exhaust valve and controlling the intake valve closing timing by controlling the closing timing of the intake valve, the cylinder volume at the closing timing of the intake valve is calculated. Means for calculating cylinder volume when the intake valve is closed, means for calculating gas density in the cylinder when the intake valve is closed, and means for calculating the total gas in the cylinder from the cylinder volume and the gas density in the cylinder when the intake valve is closed. Cylinder total gas amount calculating means for calculating the amount, exhaust valve closing cylinder volume calculating means for calculating the cylinder volume at the time of closing the exhaust valve, exhaust density calculating means for calculating the exhaust density, exhaust valve closing timing Cylinder residual gas amount calculating means for calculating the residual gas amount in the cylinder from the cylinder volume and the exhaust density of the cylinder, and calculating the fresh air amount in the cylinder by subtracting the residual gas amount in the cylinder from the total gas amount in the cylinder A cylinder intake air amount detection device for a variable valve engine, comprising: an in-cylinder fresh air amount calculating means. 2. The cylinder intake of a variable valve engine according to claim 1, wherein said in-cylinder gas density calculation means calculates the in-cylinder gas density based on the intake pressure at the time of closing the intake valve. Air volume detector. 3. The variable dynamic motor according to claim 1, wherein said in-cylinder gas density calculating means calculates the in-cylinder gas density based on the intake pressure and the intake temperature when the intake valve is closed. Cylinder intake air amount detection device for valve engines. 4. The variable valve according to claim 1, wherein said exhaust density calculating means calculates the exhaust density based on an engine speed and a load. Engine cylinder intake air amount detection device. 5. The variable valve engine according to claim 1, wherein the variable valve type intake valve and the exhaust valve are electromagnetically driven. Air volume detector.