JP2001164947A - Intake air amount control device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continuously transmit torque without a step, in a device for controlling an intake air amount by controlling closing timing of an intake valve and an area of a throttle opening. SOLUTION: An A/NV (the area of the throttle opening A/a revolution speed Ne and an exhaust amount V) corresponding to a target boost is compared with an A/NV corresponding to a target intake air amount, and the smaller A/NV is set as a target value of the A/NV. On the other hard, the closing timing of the intake valve is set depending on the target intake air amount. In a region where the intake air amount is controlled to be the target intake air amount by the closing timing, the intake air amount is controlled to be the target boost by the A/NV. In a region where the intake air amount cannot be controlled to be the target intake air mount by the closing timing, the intake air amount is controlled to be the target intake air amount by reducing the A/NV.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine intake air amount control device configured to control an engine intake air amount to a target intake air amount by controlling valve timing of an intake valve.

[0002]

2. Description of the Related Art Conventionally, there has been known an electromagnetically driven valve that includes a valve closing electromagnetic coil and a valve opening electromagnetic coil and drives an intake valve and an exhaust valve to be opened and closed by an electromagnetic force generated by the electromagnetic coil. (See Japanese Patent Application Laid-Open No. Hei 8-200025).

[0003]

By the way, with the electromagnetically driven valve, the valve timing can be controlled continuously and in a wide range, the electromagnetically driven valve is used as the intake valve, and the closing timing of the intake valve is controlled. For example, if the control is performed so that the intake air is taken in at substantially atmospheric pressure, the amount of intake air can be controlled, thereby improving the fuel efficiency by reducing the pumping loss.

However, in the case of the above-described configuration in which the intake valve is driven to open and close by electromagnetic force, the intake air amount can be reduced to the target intake air amount only by controlling the closing timing of the intake valve due to the limitation of the drive speed of the intake valve. Occasionally, an operating region that could not be controlled occurred.

That is, when the intake valve is opened and closed by electromagnetic force, the driving speed is constant (determined by the spring constant and the mass of the movable portion) regardless of the engine speed, and the closed state is changed to the open state. , And a certain operating time irrespective of the engine speed is required until the state changes from the open state to the closed state. For this reason, the minimum operating angle increases as the engine rotation speed increases. Therefore, in a low-load region where the target intake air amount is small in a high rotation region, the target intake air amount may not be controlled only by controlling the intake valve.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems. In an apparatus for controlling the amount of intake air by controlling the valve timing of an intake valve, even if the control of the valve timing is restricted, a wide range of intake is achieved. In addition to controlling the air amount, the torque can be smoothly changed when switching between a region where the target intake air amount can be controlled by controlling the valve timing and a region where the target intake air amount cannot be controlled by controlling the valve timing. The purpose is to be able to connect.

[0007]

Therefore, according to the present invention, a constant target boost is achieved while controlling the intake air amount of the engine to the target intake air amount by controlling the valve timing of the intake valve. As described above, while the opening area of the throttle valve is controlled to be smaller as the target intake air amount is smaller, when the target intake air amount is equal to or less than the control limit of the intake air amount based on the valve timing, the opening area of the throttle valve is reduced. The intake air amount of the engine is controlled to the target intake air amount by decreasing the opening area corresponding to the target boost.

According to this configuration, in a region where the target intake air amount is controlled by controlling the valve timing (closing timing) of the intake valve, a constant target boost is obtained.
The smaller the target intake air amount, the smaller the throttle opening area is changed. Then, when the limit of the intake air amount control by the valve timing is exceeded, that is, when the target intake air amount becomes smaller than the intake air amount obtained at the minimum operation angle, the opening area corresponding to the constant boost up to that point is obtained. Also, the throttle opening area is reduced, and the amount of air obtained in the minimum operating angle state is reduced and changed by boost control.

According to the second aspect of the present invention, the opening area of the throttle valve for obtaining the target boost is determined, and the opening area of the throttle valve for obtaining the target intake air amount is determined. And select
The throttle valve is driven based on the selected opening area.

With this configuration, the throttle opening area for obtaining the target boost determined according to the target intake air amount is compared with the throttle opening area determined by the valve timing and the target intake air amount. Is selected, and the throttle valve is driven according to the selected throttle opening area.

That is, when the target intake air amount becomes smaller than the lower limit value of the intake air amount which can be controlled by controlling the valve timing in a state where the throttle valve is controlled to a constant target boost, the throttle opening area is made smaller than the target boost. As a result, the throttle opening area determined by the valve timing and the target intake air amount is selected.On the other hand, when the target intake air amount is larger than the lower limit, a certain target boost is set. The throttle opening area to be obtained will be selected.

According to the present invention, the opening area of the throttle valve for obtaining the target intake air amount at the reference valve timing is stored in advance as a reference characteristic, and the target intake air at the valve timing at that time is stored based on the reference characteristic. The configuration was such that the opening area for obtaining the amount was estimated.

According to this structure, the correlation between the intake air amount and the throttle opening area at each valve timing is not stored, but the correlation between the intake air amount and the throttle opening area at the reference valve timing is used as a reference. Characteristics are stored in advance, and an opening area for obtaining a target intake air amount at an actual valve timing at that time is estimated from the reference characteristics.

According to the present invention, the ratio of the intake air amount at the throttle opening area serving as the target boost in the reference characteristic to the lower limit value of the intake air amount which can be controlled by valve timing at that time is determined. Converting the target intake air amount at that time into a value for referencing the reference characteristic based on the ratio, obtaining an opening area corresponding to the converted target intake air amount from the reference characteristic, The obtained opening area is converted into the opening area at the valve timing at that time based on the ratio.

According to this configuration, the lower limit value of the intake air amount which can be controlled by the valve timing at that time is the intake air amount (the lower limit value of the intake air amount) obtained at the minimum operating angle at the engine speed at that time. And the intake air amount obtained in the target boost state. here,
Assuming that the correlation between the intake air amount and the throttle opening area at each valve timing is similar, the ratio indicates a similar ratio. Therefore, the target intake air amount at that time is converted into a target intake air amount on the reference characteristic based on the ratio, and the throttle opening area is searched for by referring to the reference characteristic based on the converted target intake air amount,
Further, the retrieved throttle opening area is converted into an opening area for obtaining a target intake air amount at the minimum operating angle based on the ratio.

[0016]

According to the first aspect of the present invention, it is possible to control the target intake air amount even in a region below the control limit by the valve timing, and to control an arbitrary boost state in the region where the intake air amount is controlled by the valve timing. Thus, there is an effect that the engine can be used as a negative pressure supply source.

According to the second aspect of the present invention, switching between the control of the intake air amount by the valve timing and the control of the intake air amount by the throttle opening area can be performed in the same control air amount state. Therefore, there is an effect that the torque can be smoothly connected.

According to the third aspect of the present invention, it is not necessary to store the correlation between the intake air amount and the throttle opening area for each valve timing, and there is an effect that the storage capacity required for intake air amount control can be saved. .

According to the present invention, the throttle opening area for obtaining the target intake air amount at the valve timing at that time can be simply determined based on the correlation between the intake air amount at the reference valve timing and the throttle opening area. The effect is that it can be estimated.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1 showing the overall configuration of the embodiment, a four-cycle gasoline engine 1 for a vehicle includes:
An intake valve 3 and an exhaust valve 4 whose opening / closing timing is electronically controlled by an electromagnetic valve mechanism 2 are mounted on each cylinder.

An injector 6 is mounted on the intake port 5 on the upstream side of the intake valve 3 of each cylinder, and an ignition plug 8 is mounted on the combustion chamber 7. An ignition coil 9 is provided for each ignition plug 8.

The main body of the engine 1 outputs a reference signal at a reference piston position of each cylinder, outputs a unit angle signal for each unit crank angle, a crank angle sensor 10, an air flow meter 11 for detecting intake air flow, A water temperature sensor 12 for detecting a cooling water temperature is mounted. In addition, an accelerator opening sensor 13 for detecting the opening APO of an accelerator pedal of the vehicle (not shown), a vehicle speed sensor 14, and the like are provided.

The detection signals of the various sensors are output to the control unit 15, and the control unit 15
Based on these detection signals, an injection pulse signal is output to the injector 6 to control the fuel injection amount and fuel injection timing, and an ignition signal is output to the ignition coil 9 to control the ignition timing. A valve drive signal is output to the electromagnetic valve mechanism 2 to control the valve timing of the intake valve 3 and the exhaust valve 4.

A throttle valve 16 is provided upstream of the intake port 5, and the throttle valve 16 is opened and closed by a motor 17 as an actuator.

FIG. 2 shows the structure of the electromagnetic valve mechanism 2.
In FIG. 2, an electromagnetic valve mechanism 2 includes a housing 21 made of a non-magnetic material provided on a cylinder head, and an intake valve 3.
(Or an exhaust valve 4, hereinafter represented by the intake valve 3). An armature 22 provided integrally with the stem 31 and movably housed in a housing 21, and the intake valve 3 is closed by sucking the armature 22. A valve-closing electromagnet 23 fixedly disposed in the housing 21 at a position facing the upper surface of the armature 22 so as to exert an electromagnetic force to be actuated, and an electromagnetic valve for attracting the armature 22 and opening the intake valve 3. A valve-opening electromagnet 24 fixedly arranged in the housing 21 at a position facing the lower surface of the armature 22 so as to exert a force.
And a valve-closing-side return spring 25 for urging the armature 22 toward the valve closing direction of the intake valve 3, and a valve-opening-side return spring 26 for urging the armature 22 toward the valve opening direction of the intake valve 3.
And is provided. Then, when the valve closing electromagnet 23 and the valve opening electromagnet 24 are both demagnetized, the intake valve 3 is positioned substantially at the center between the fully open position and the valve closed position.
When the spring force between the valve-closing-side return spring 25 and the valve-opening-side return spring 26 is set and only the valve-closing electromagnet 23 is excited, the intake valve 3 is closed, and only the valve-opening electromagnet 24 is excited. The intake valve 3 is driven to open.

The valve timing of the intake valve 3 and the exhaust valve 4 by the electromagnetic valve mechanism 2 is controlled so as to be a target valve timing set based on the operating conditions of the engine 1. Closing time I
VC is determined based on a target intake air amount (specifically, a target value of a volume flow ratio which is a volume in a standard state of a fresh air amount with respect to a stroke volume) set based on an accelerator opening APO and an engine rotation speed Ne. The cylinder intake air amount is controlled for each cylinder by variably controlling in the early closing direction.

The opening timing of the intake valve 3 is fixed near the top dead center of the exhaust gas. Hereinafter, the closing timing IV of the intake valve 3
The manner of controlling the intake air amount by C (valve timing) will be described in detail.

FIG. 3 is a control block diagram showing how the control unit 15 controls the amount of intake air. In the target intake air amount calculation unit 101, the target intake air amount is set in advance in accordance with the accelerator opening APO and the engine speed Ne. A target intake air amount corresponding to the accelerator opening APO and the engine rotation speed Ne at that time is retrieved from a map storing the air amount (see FIG. 4).

Incidentally, the amount of air required for idling operation is added to the target intake air amount obtained according to the accelerator opening APO and the engine speed Ne as described above, and this is added to the final target intake air. It is preferred to be an amount.

On the other hand, the threshold value calculating section 102 sets a threshold value which is a lower limit air amount at which the intake air amount can be controlled by the closing timing IVC (valve timing) of the intake valve 3.
It is determined based on the engine speed Ne at that time.

In the electromagnetically driven intake valve 3, there is a restriction on the minimum operating time, and the minimum operating angle becomes large on the high rotation side, and the low load / high rotation area (the area shaded in FIG. 5) The region cannot be controlled to the target intake air amount (target torque) by the early closing control.
This corresponds to the air amount at the boundary between the valve timing control region and the throttle control region shown in FIG.

That is, in the electromagnetic valve mechanism 2, the valve driving speed is constant irrespective of the engine rotation speed.
Since a certain minimum operation time is required, the minimum operation angle is large in the high rotation region (the closing timing is delayed by the crank angle). Therefore, the intake air amount obtained when the intake valve 3 is opened and driven by the electromagnetic valve mechanism 2 near the minimum operation time (the air amount at the boundary between the valve timing control region and the throttle control region shown in FIG. 5: The threshold value increases as the rotation speed increases, and in the high rotation range, a region where the intake air amount cannot be controlled to the target intake air amount even when the intake valve 3 is opened and driven near the minimum operation time occurs. In the present embodiment, a region where the intake air amount can be controlled to the target intake air amount by the valve timing is referred to as a valve timing control region. In a region where the intake air amount cannot be controlled by the valve timing, the intake air amount is targeted by the throttle opening area. Since the air amount is controlled, this region is referred to as a throttle control region.

The data of the threshold value is output to a target intake valve timing calculation section 103. The target intake valve timing calculation section 103 compares the threshold value with a target intake air amount to perform valve timing control. It is determined whether the area is the area or the throttle control area.

Here, if the target intake air amount is in the valve timing control region larger than the threshold value, a table (see FIG. 6) storing the closing timing IVC of the intake valve 3 according to the target intake air amount is stored. A search is performed, and a closing timing IVC corresponding to the target intake air amount at that time is obtained as a target value.
On the other hand, if the target intake air amount is in a throttle control region smaller than the threshold value, the closing timing corresponding to the predetermined minimum operation time is set so that the intake valve 3 is opened and driven with a predetermined predetermined minimum operation time. The IVC is set as a target value in accordance with the engine speed Ne at that time so that the intake valve 3 is driven to open at the minimum operating angle for each rotation.

Then, the electromagnetic valve mechanism 2 is closed to close the intake valve 3 at the set target value of the closing timing.
To output a control signal. The opening timing of the intake valve 3 is
It shall be fixed near the exhaust top dead center.

A / NV calculation unit based on target boost
At 104, the value "throttle opening area A / (engine speed Ne / displacement V)" (hereinafter referred to as A / NV) for obtaining a constant target boost is obtained as shown in FIG. The calculation is performed based on the target intake air amount. The target A / NV calculated by the target boost A / NV calculator 104 is a target value for controlling the boost to a constant target boost in a region where the intake air amount is controlled to the target intake air amount by the valve timing. And is set as a characteristic that monotonously decreases in accordance with a decrease in the target intake air amount.

The target boost is set, for example, for the purpose of securing a negative pressure source necessary for supplying purge air from the canister to the engine, and is controlled to the target boost to provide a constant boost (negative boost). Pressure) to enable canister purging and the like.

On the other hand, in the target air amount similar expansion section 105, based on the threshold value and the reference air amount KOUTEN # stored in advance, the target intake air amount is set to the target intake air amount corresponding to the reference valve timing and A A / NV is converted into a value for searching for A / NV based on the correlation with / NV (reference characteristic).

That is, the correlation between the target intake air amount and the A / NV changes according to the valve timing (closing timing IVC) at that time as shown in FIG. 8, but in this embodiment, it is the latest. Only the correlation between the target intake air amount and A / NV when the closing timing is IVC (maximum operating angle) is stored in advance as a reference characteristic.

In the reference characteristics, the air amount corresponding to A / NV corresponding to the target boost is the reference air amount KOUTEN #, and the threshold value is the minimum operation at the engine speed Ne at that time. It is the amount of intake air obtained when the angle is set, and in the valve timing control region,
Since the throttle valve 16 is controlled so as to achieve a constant target boost, the air amount corresponding to the target boost corresponding A / NV at the minimum operating angle at the engine rotation speed Ne at that time is determined. (See FIG. 9).

It is considered that the correlation between the A / NV and the intake air amount for each valve timing is similar to each other. Therefore, the target air amount similar enlargement unit 105 multiplies the target intake air amount by the ratio of the reference air amount and the threshold value (reference air amount / threshold value) to obtain the target intake air amount. Is performed in a similar manner to the value corresponding to. That is, the above-mentioned processing sets the point corresponding to the target intake air amount on the characteristic curve corresponding to the minimum operating angle (valve timing) at the engine rotation speed Ne at that time to a position similar to the reference characteristic. This is a process for conversion.

The similar-expansion A / NV calculator 106 calculates the A / NV corresponding to the similar-expanded target intake air amount by referring to the reference characteristic based on the similar-expanded target intake air amount. .

The A / NV similar reduction section 107 divides A / NV obtained from the reference characteristic based on the similar expanded target intake air amount by the ratio (reference air amount / threshold value). Thus, the engine speed N at that time
The characteristic is reduced to a value similar to the A / NV corresponding to the target intake air amount on the characteristic curve corresponding to the minimum operating angle (valve timing) at e.

The select row section 108 controls the A / NV for controlling the target boost calculated by the A / NV calculating section 104 based on the target boost, and the A / NV similar reduction section.
At 107, the smaller one of A / NV for obtaining the finally obtained target intake air amount is selected, and the selected A / NV is output.

The output A / NV is multiplied by the engine speed Ne and the displacement V to obtain a target throttle opening area, and a drive control signal corresponding to the target throttle opening area is output to the motor 17. , Throttle valve 16
To the throttle opening area.

In the valve timing control region, the A / NV is controlled to correspond to a predetermined target boost, while the valve timing (closing timing IVC) is changed in accordance with the target intake air amount by the selection in the select low section 108. The intake air amount is controlled to the target intake air amount. On the other hand, when shifting from the valve timing control region to the throttle control region, as shown in FIG. 9, the A / NV that has been controlled so far corresponding to the target boost is controlled to be smaller according to the decrease in the target intake air amount. The target intake air amount is controlled by boost control.

Here, A / A in the valve timing control area
Since the target of A / NV continuously changes from NV to A / NV in the throttle control region, switching is performed in the same control air amount state by the above-mentioned select low process, and torque is smoothly changed without a step. It will be connected.

Since the minimum operating angle of the intake valve 3 changes in accordance with the engine speed Ne, an area in which the air amount is controlled by A / NV (A / NV corresponding to the target boost).
The control characteristic of A / NV in the following region) changes according to the minimum operating angle at that time, as shown in FIG.

The flowcharts of FIGS. 10 to 12 correspond to FIG.
Throttle opening area (A / N) shown in the control block diagram of FIG.
This shows the control contents of V). The flowchart of FIG. 10 shows the A / NV calculation process for obtaining the target intake air amount. In S1, the target intake air amount is set, in S2, the reference air amount KOUTEN #, and in S3, the threshold value is set. Read in.

At S4, the reference air amount KOUTEN
#, A process for expanding the target intake air amount to a value similar to the reference characteristic based on the threshold value. In S5, A / NV for obtaining the target intake air amount is determined by referring to the reference characteristic based on the target intake air amount that has been similarly enlarged.

In S6, the A / N obtained on the reference characteristic is calculated.
V is subjected to similar reduction processing in the direction opposite to the similar expansion of the target intake air amount, and is converted to A / NV for obtaining the target intake air amount at the actual valve timing.

At S7, A / NV for obtaining the target intake air amount obtained at S6 is output. The flowchart of FIG. 11 shows the A / NV for controlling to a constant target boost.
In S11, a target intake air amount is read, in S12, a coefficient corresponding to a constant target boost is read, and in S13, based on the target intake air amount and the coefficient, A / NV for obtaining the target boost at the target intake air amount is obtained.

In S14, A / NV for outputting the target boost obtained in S13 is output. The flowchart of FIG. 12 shows the select row processing, and S
At 21, the A / NV (output of S14) for obtaining the target boost is read, and at S22, the A / NV (output of S6) for obtaining the target intake air amount is read.

Then, in S23, a process of selecting the smaller one of A / NV (output of S14) for obtaining the target boost and A / NV (output of S6) for obtaining the target intake air amount is performed. .

In S24, the selected A / NV is output as a final target for actually driving the throttle valve 16. The boundary between the valve timing control region and the throttle control region shown in FIG. 5 is set to a value slightly higher than the air amount at the minimum operation angle corresponding to the minimum operation time, and even if there are various variations, It is preferable that the intake air amount can be reliably controlled in the valve timing control region.

[Brief description of the drawings]

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

FIG. 2 is a sectional view showing details of an electromagnetic valve mechanism.

FIG. 3 is a control block diagram of an intake air amount.

FIG. 4 is a diagram showing a map of a target intake air amount.

FIG. 5 is a diagram showing control characteristics of an intake air amount.

FIG. 6 is a diagram showing a table of intake valve closing timing;

FIG. 7 is a diagram showing a table of A / NV for setting a target boost.

FIG. 8 is a diagram showing a correlation between a target intake air amount and A / NV for each valve timing.

FIG. 9 is a diagram showing A / NV characteristics when a select row process is performed.

FIG. 10 is a flowchart showing A / NV calculation processing for obtaining a target intake air amount.

FIG. 11 is a flowchart illustrating an A / NV calculation process for setting a target boost.

FIG. 12 is a flowchart illustrating A / NV select row processing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2 Electromagnetic valve mechanism 3 Intake valve 4 Exhaust valve 6 Injector 7 Combustion chamber 8 Ignition plug 10 Crank angle sensor 11 Air flow meter 12 Water temperature sensor 13 Accelerator opening sensor 15 Control unit 16 Throttle valve 17 Motor 101 Target intake air amount calculation Section 102 threshold value calculation section 103 target intake valve timing calculation section 104 A / NV calculation section by target boost 105 target air amount similar expansion section 106 similar expansion A / NV calculation section 107 A / NV similar reduction section 108 select low section

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) F02D 43/00 301 F02D 43/00 301K 301Z F term (reference) 3G065 CA21 DA07 GA05 GA10 GA15 3G084 BA03 BA04 BA05 BA23 DA05 FA07 FA10 FA18 FA33 3G092 BA01 BA03 DA03 DC01 DG09 FA03 HA01X HA06X HA13X HE01X 3G301 HA19 JA03 LA01 LA07 LC01 PA01A PA11A PE01A PE10A

Claims (4)

[Claims] An intake air amount of an engine is controlled to a target intake air amount by controlling a valve timing of an intake valve, and an opening area of the throttle valve is adjusted so that the target intake air amount becomes a constant target boost. On the other hand, when the intake air amount is smaller than the control limit of the intake air amount by the valve timing, the opening area of the throttle valve is made smaller than the opening area corresponding to the target boost to reduce the engine. An intake air amount control device for an engine, wherein an intake air amount is controlled to the target intake air amount. 2. An opening area of a throttle valve for obtaining the target boost is obtained, while an opening area of a throttle valve for obtaining the target intake air amount is obtained, and a smaller one of them is selected. 2. The engine intake air amount control device according to claim 1, wherein the throttle valve is driven based on the determined opening area. 3. An opening area for obtaining a target intake air amount at a valve timing at that time from a reference valve characteristic in which an opening area of a throttle valve for obtaining a target intake air amount at a reference valve timing is stored in advance as a reference characteristic. 3. The intake air amount control device for an engine according to claim 2, wherein the area is estimated. 4. A ratio between an intake air amount at the throttle opening area serving as the target boost in the reference characteristic and a lower limit value of the intake air amount which can be controlled by valve timing at that time is determined, and based on the ratio. The target intake air amount at that time is converted into a value for referencing the reference characteristic, an opening area corresponding to the converted target intake air amount is determined from the reference characteristic, and an opening area determined from the reference characteristic is 4. The intake air amount control device for an engine according to claim 3, wherein the ratio is converted into an opening area at the valve timing at that time based on the ratio.