JP3684964B2 - Engine intake air amount control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine intake air amount control apparatus configured to control an intake air amount of an engine to a target intake air amount by valve timing control of an intake valve.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there has been known an electromagnetically driven valve having a valve closing electromagnetic coil and a valve opening electromagnetic coil and configured to open and close an intake valve and an exhaust valve by electromagnetic force generated by the electromagnetic coil (Japanese Patent Laid-Open No. 8- No. 200025).
[0003]
[Problems to be solved by the invention]
By the way, if it is the electromagnetically driven valve, the valve timing can be controlled continuously and over a wide range, and the electromagnetically driven valve is used as the intake valve, and the closing timing of the intake valve is advanced, for example (early closing control). By doing so, it becomes possible to control the amount of intake air while taking in the intake air at atmospheric pressure, thereby improving the fuel efficiency by reducing the pumping loss.
[0004]
However, in the case where the intake valve is driven to open and close with electromagnetic force as described above, the intake air amount is controlled 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. There was a case where there was an operation area that could not be performed.
[0005]
That is, when the intake valve is driven to open and close by electromagnetic force, the drive speed is constant (determined by the spring constant and the mass of the movable part) regardless of the engine rotation speed, and changes from the closed state to the open state. In addition, a certain operation time that is unrelated to the engine speed is required until the engine changes from the open state to the closed state. For this reason, the minimum operating angle increases as the engine speed increases. Therefore, in a low load region where the target intake air amount is small and in a high rotation range, the target intake air amount may not be controlled only by controlling the intake valve.
[0006]
The present invention has been made in view of the above problems, and in an apparatus for controlling the intake air amount by controlling the valve timing of the intake valve, the intake air amount can be controlled over a wide range even if the valve timing control is limited. The purpose is to be able to control.
[0007]
Furthermore, it is intended to maximize the area in which the intake air amount can be controlled while taking in the intake air at atmospheric pressure, and to sufficiently obtain the fuel efficiency improvement effect by reducing the pumping loss. .
[0008]
[Means for Solving the Problems]
Therefore, the invention according to claim 1 includes an electromagnetic valve mechanism that opens and closes an intake valve by an urging force of a spring and an electromagnetic force of an electromagnet, and intake air of an engine that includes a throttle valve that is opened and closed by an actuator. This is a quantity control device, which is capable of controlling the valve timing control region in which the throttle valve is fixed substantially fully open and controlled to the target intake air amount by the early closing control of the intake valve closing timing and the operating angle of the intake valve. The minimum operating angle of the intake valve according to the engine rotational speed is determined to be either a throttle control region that is fixed near the minimum operating angle and controlled to the target intake air amount by the throttle valve opening control. It was set as the structure judged according to .
[0011]
According to such a configuration, since the minimum operating angle of the intake valve that is driven to open and close by the electromagnetic valve mechanism varies depending on the engine speed, the target intake air can be controlled even if the valve timing of the intake valve is controlled near the minimum operating angle that can be controlled. It is determined whether it is a region that cannot be controlled by the amount based on the engine speed, and if it is a region that cannot be controlled to the target intake air amount by the minimum operating angle, the throttle valve is closed and the target intake air amount is controlled, In other cases, the throttle valve is held fully open, and the target intake air amount is controlled by early closing control of the intake valve closing timing .
[0012]
In the second aspect of the present invention, an intake air amount corresponding to the boundary between the valve timing control region and the throttle control region is obtained according to the engine speed, and any of the intake air amount and the target intake air amount is compared with each other. It is configured to determine whether it falls within the area.
[0013]
According to such a configuration, it varies with the engine speed minimum operating angle of the intake valve driven to open and close by an electromagnetic valve operating mechanism, I hereinafter, the minimum amount of intake air which can be early closing control to thus control of the intake valve is changed The minimum intake air amount is obtained from the engine speed at that time, and depending on whether the target intake air amount is larger than the minimum intake air amount as the threshold value, either the valve timing control region or the throttle control region is determined. Judge whether it is.
[0014]
【The invention's effect】
According to the first aspect of the present invention, an area determination is made in response to a change in the minimum operating angle of the intake valve that is driven to open and close by the electromagnetic valve mechanism depending on the engine speed, and the target intake is controlled by the early closing control of the intake valve. In the region where the amount of air can be controlled, the throttle valve is fixed in the fully open state and the early closing control is executed. Therefore, the pumping loss can be reduced and the intake air amount can be controlled. In a region where control is not possible, the target intake air amount can be controlled by reducing the opening of the throttle valve .
[0016]
According to the second aspect of the present invention, there is an effect that it is possible to accurately determine which of the intake valve timing and the throttle opening by the early closing control should be changed according to the target intake air amount.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
In FIG. 1 showing the overall configuration of the embodiment, 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 in a four-cycle gasoline engine 1 for a vehicle. Yes.
[0018]
An injector 6 is attached to the intake port 5 upstream of the intake valve 3 of each cylinder, and an ignition plug 8 is attached to the combustion chamber 7. An ignition coil 9 is provided for each ignition plug 8.
[0019]
The main body of the engine 1 outputs a reference signal at the reference piston position of each cylinder and outputs a unit angle signal for each unit crank angle, an air flow meter 11 for detecting an intake air flow rate, and a cooling water temperature. A water temperature sensor 12 for detecting the In addition, an accelerator opening sensor 13 and a vehicle speed sensor 14 for detecting an accelerator pedal opening APO of a vehicle (not shown) are provided.
[0020]
Detection signals from the various sensors are output to the control unit 15, and the control unit 15 outputs an injection pulse signal to the injector 6 based on these detection signals to control the fuel injection amount and fuel injection timing. An ignition signal is output to the ignition coil 9 to control the ignition timing, and 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.
[0021]
Further, a throttle valve 16 is interposed upstream of the intake port 5, and the throttle valve 16 is driven to open and close by a motor 17 as an actuator.
[0022]
The configuration of the electromagnetic valve mechanism 2 is shown in FIG.
In FIG. 2, the electromagnetic valve mechanism 2 is provided integrally with a housing 21 made of a non-magnetic material provided on the cylinder head and a stem 31 of an intake valve 3 (or an exhaust valve 4, hereinafter represented by the intake valve 3). The armature 22 that is freely moved in the housing 21 and the inside of the housing 21 at a position facing the upper surface of the armature 22 so as to exert an electromagnetic force that sucks the armature 22 and closes the intake valve 3. The valve closing electromagnet 23 fixedly arranged in the housing and the housing 21 fixedly arranged in a position facing the lower surface of the armature 22 so as to exert an electromagnetic force for attracting the armature 22 and opening the intake valve 3 The valve opening electromagnet 24, the valve closing side return spring 25 for urging the armature 22 toward the valve closing direction of the intake valve 3, and the armature 22 toward the valve opening direction of the intake valve 3 are attached. The spring 26 returns the valve opening side, configured with a. Then, when both the valve closing electromagnet 23 and the valve opening electromagnet 24 are demagnetized, the valve closing side return spring 25 and the valve closing side return spring 25 are arranged so that the intake valve 3 is at a substantially central position between the fully opened position and the valve closing position. When the spring force with the valve-opening return spring 26 is set and only the valve closing electromagnet 23 is excited, the intake valve 3 is closed, and when only the valve opening electromagnet 24 is excited, the intake valve 3 is opened. To be driven.
[0023]
The valve timing of the intake valve 3 and the exhaust valve 4 by the electromagnetic valve mechanism 2 is controlled to be a target valve timing set based on the operating conditions of the engine 1, and in particular, the closing timing of the intake valve 3. The IVC is variably controlled in the early closing direction based on a target intake air amount (target cylinder intake air amount: target torque) set based on the accelerator opening APO and the engine rotational speed Ne, and each cylinder intake air amount is changed. Control is performed for each cylinder.
[0024]
The closing timing IVC is controlled before the intake bottom dead center, so that a so-called early closing mirror cycle operation is performed.
As described above, the closing timing IVC of the intake valve 3 is controlled to be quickly closed to control the intake air amount to the target intake air amount. However, as shown in FIG. The region (the region shown by hatching in FIG. 3) is a region that cannot be controlled to the target intake air amount (target torque).
[0025]
That is, in the electromagnetic valve mechanism 2, since the valve driving speed is constant regardless of the engine rotational speed and a certain minimum operation time is required, the minimum operating angle becomes large in the high rotation region (closing timing) Is slower at the crank angle). Therefore, the intake air amount obtained when the intake valve 3 is driven to open near the minimum operating time by the electromagnetic valve mechanism 2 with the throttle valve 16 being fully open (the valve timing control region shown in FIG. The air amount at the boundary with the throttle control area) increases as the engine speed increases. In the high engine speed region, there is a region where the target intake air amount cannot be controlled even if the intake valve 3 is driven open near the minimum operating time. is there.
[0026]
Therefore, in the present embodiment, in the region where the intake air amount can be controlled to the target intake air amount by the early closing control (the valve timing control region shown in FIG. 3), the throttle valve 16 is held substantially fully open, In the region where the closing timing IVC of the intake valve 3 is variably controlled according to the amount, but cannot be controlled to the target intake air amount even when the intake valve 3 is at the minimum operating angle (throttle control region shown in FIG. 3), While the intake valve 3 is kept open at a substantially minimum operating angle, the opening of the throttle valve 16 is variably controlled in accordance with the target intake air amount.
[0027]
Specifically, the control unit 15 performs coordinated control of valve timing control of the intake valve 3 and opening control of the throttle valve 16 as shown in the control block diagram of FIG.
[0028]
In FIG. 4, the target intake air amount calculation unit 101 uses a map (see FIG. 5) in which the target intake air amount is stored in advance according to the accelerator opening APO and the engine speed Ne, and the accelerator opening APO at that time and A target intake air amount corresponding to the engine speed Ne is searched.
[0029]
Note that, as described above, an air amount necessary for idle operation is added to the target intake air amount determined in accordance with the accelerator opening APO and the engine speed Ne, and this is used as the final target intake air amount. It is preferable.
[0030]
The target intake air amount calculated by the target intake air amount calculation unit 101 is output to the target throttle opening calculation unit 102 and the target intake valve timing calculation unit 103, respectively. In addition to the target intake air amount, a signal of the engine speed Ne is input to the target throttle opening calculation unit 102 and the target intake valve timing calculation unit 103.
[0031]
In the target throttle opening calculation unit 102, an air amount (threshold value) at the boundary between the valve timing control region and the throttle control region at the engine speed Ne at that time is searched from a table as shown in FIG. By comparing the retrieved threshold value with the target intake air amount, it is determined whether it is the valve timing control region or the throttle control region. The threshold value is output to the target intake valve timing calculation unit 103.
[0032]
Here, in the valve timing control region, the target throttle opening is fixed at full open, and in the throttle control region, the target for obtaining the target intake air amount based on the target intake air amount and the engine rotational speed Ne. An opening area is obtained, and then the target opening area is converted into a target throttle opening. Then, an opening / closing drive signal is output to the motor 17 in order to drive the throttle valve 16 to the target throttle opening.
[0033]
On the other hand, the target intake valve timing calculation unit 103 compares the threshold value output from the target throttle opening calculation unit 102 with the target intake air amount, and in either the valve timing control region or the throttle control region. Determine if there is.
[0034]
Here, in the valve timing control region, a table (see FIG. 6) storing the closing timing IVC of the intake valve 3 according to the target intake air amount is searched, and the closing corresponding to the target intake air amount at that time is searched. Find the time IVC. On the other hand, in the throttle control region, in order to drive the intake valve 3 to open in a certain minimum operation time, a closing timing IVC corresponding to the certain minimum operation time is set as a target value according to the engine speed Ne, The intake valve 3 is driven to open at the minimum operating angle for each rotation.
[0035]
Then, a control signal is output to the electromagnetic valve mechanism 2 to close the intake valve 3 at the closing timing. It is assumed that the opening timing of the intake valve 3 is fixed near the exhaust top dead center.
[0036]
Here, the state of the intake air amount control will be described in detail according to the flowchart of FIG.
In the flowchart of FIG. 7, the accelerator opening APO is read in S1, the engine speed Ne is read in S2, and the target intake air amount is calculated based on the accelerator opening APO and the engine speed Ne in S3.
[0037]
The portions S1 to S3 correspond to the target intake air amount calculation unit 101.
When the processing of S3 is completed, the calculation processing of the target throttle opening after S11 and the calculation processing of the target valve timing after S21 are executed in parallel.
[0038]
Here, the processing of S11 to S15 corresponds to the target throttle opening calculation unit 102, and the processing of S21 to S25 corresponds to the target intake valve timing calculation unit 103.
In S11, the engine rotation speed Ne is read. In S12, it is determined whether or not the valve timing control region is in the target intake air amount and the engine rotation speed Ne.
[0039]
Whether or not it is the valve timing control region is determined by obtaining an intake air amount (threshold value) corresponding to the boundary between the valve timing control region and the throttle control region in accordance with the engine speed Ne at that time (see FIG. 3), the threshold value of the intake air amount is compared with the target intake air amount at that time.
[0040]
When it is in the valve timing control region, the process proceeds to S13, and the target throttle opening in the valve timing control region is calculated. Specifically, the target throttle opening is fixed to be substantially fully open.
[0041]
On the other hand, when it is in the throttle opening control region, the process proceeds to S14, and the intake air amount (threshold value) corresponding to the boundary between the valve timing control region and the throttle control region is set to the target valve timing calculation processing side (target intake air). To the valve timing calculation unit 103).
[0042]
In the next S15, a target opening area is obtained based on the engine speed Ne and the target intake air amount, and a process for obtaining the target throttle opening from the target opening area is performed.
On the other hand, the engine speed Ne is read in S21, and the threshold value of the intake air amount output from S14 (target throttle opening calculation unit 102) is read in S22.
[0043]
In S23, the threshold value is compared with the target intake air amount to determine which of the valve timing control region and the throttle control region is applicable.
[0044]
Here, when it is determined that it is in the valve timing control region, the process proceeds to S24, and the closing timing IVC (target valve timing) of the intake valve 3 is calculated according to the target intake air amount (see FIG. 6).
[0045]
On the other hand, when it is determined that it is in the throttle control region, the routine proceeds to S25, where the intake valve 3 is driven according to the engine speed Ne in order to open the intake valve 3 at a constant operating time (substantially minimum operating angle) near the minimum operating time. A closing timing IVC (target valve timing) corresponding to a certain operation time is calculated (see FIG. 8). That is, the closing timing IVC set in S25 is a value such that the time from the opening timing to the closing timing becomes a certain minimum operation time regardless of the engine rotation speed. It is a value indicating the minimum operating angle.
[0046]
When the target throttle opening and the target valve timing (target closing timing) are calculated as described above, in S31, control signals corresponding to the target throttle opening and target valve timing (target closing timing) are sent to the motor 17, Output to the electromagnetic valve mechanism 2.
[0047]
Note that the boundary between the valve timing control area and the throttle control area shown in FIG. 3 is set to a value slightly higher than the air amount at the minimum operating angle corresponding to the minimum operation time. It is preferable that the intake air amount can be reliably controlled in the valve timing control region.
[0048]
Also, the throttle control area should be as small as possible including the area that cannot be controlled to the target intake air amount only by valve timing control, so that the pumping loss reduction effect can be maximized, but at least valve timing control However, the throttle control region shown in FIG. 3 may be expanded to a low rotation and low load side, for example, as long as it includes a region that cannot be controlled by the target intake air amount alone.
[Brief description of the drawings]
FIG. 1 is a system diagram of an engine in an embodiment.
FIG. 2 is a sectional view showing details of an electromagnetic valve mechanism.
FIG. 3 is a diagram illustrating control characteristics of intake air amount.
FIG. 4 is a control block diagram of an intake air amount.
FIG. 5 is a diagram showing a map of a target intake air amount.
FIG. 6 is a diagram showing a table of intake valve closing timing.
FIG. 7 is a flowchart showing details of intake air amount control.
FIG. 8 is a diagram showing a characteristic of closing timing in a throttle control region.
[Explanation of symbols]
1 Engine 2 Electromagnetic valve mechanism 3 Intake valve 4 Exhaust valve 6 Injector 7 Combustion chamber 8 Spark plug
10 Crank angle sensor
11 Air flow meter
12 Water temperature sensor
13 Accelerator position sensor
15 Control unit
16 Throttle valve
17 Motor

Claims (2)

An engine intake air amount control device having an electromagnetic valve mechanism that opens and closes an intake valve by an urging force by a spring and an electromagnetic force by an electromagnet, and a throttle valve that is driven to open and close by an actuator,
The throttle valve is fixed almost fully open, and the valve timing control region for controlling the target intake air amount by the early closing control of the intake valve closing timing and the operating angle of the intake valve are fixed near the minimum operating angle that can be controlled. Then, it is determined according to a change in the minimum operating angle of the intake valve according to the engine speed whether the throttle control region is controlled to the target intake air amount by the opening degree control of the throttle valve. Engine intake air amount control device. The intake air amount corresponding to the boundary between the valve timing control region and the throttle control region is obtained according to the engine speed, and it is determined which region corresponds to the comparison between the intake air amount and the target intake air amount. The intake air amount control device for an engine according to claim 1, wherein

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