JPH03217631A - Intake air controller of internal combustion engine - Google Patents

Abstract

PURPOSE:To control intake air quantity high accurately by storing a control result set at an idle-up operation time of a second opening/closing valve arranged parallelly to a first opening/closing valve, and controlling the second opening/closing valve at a normal idle operation time based thereon. CONSTITUTION:A second opening/closing valve F is arranged at a communication passage E which communicates with the downstream of a first opening/ closing valve D of an intake passage C at every cylinder. Intake air flow quantity passes therethrough is varied according to closing/opening of an intake valve A. The second opening/closing valve F is controlled by an idle-up timing control means G by correcting an unbalance condition of output torque between cylinders at the idle-up operation condition set higher than the normal idle operation timing. The control result is stored in a memory means H by means of a writing means I, and the control result from the memory means H is retrieved by a retrieving means J at the normal idle operation time. Each control opening/closing valve F is controlled by a normal idle timing control; means K based on the control result. With this simple structure, a pumping loss is decreased, and an intake air flow quantity is controlled accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an intake air control device for an internal combustion engine that controls the amount of air taken into a cylinder.

(Prior Art) As a conventional example of an intake air control device for an internal combustion engine, the S. A.
There is one as shown in Fig. 2 of E. Paper 880388.

That is, a rotary harp is interposed in the intake passage upstream of the intake valve, and the rotary valve is opened in synchronization with the opening and closing of the intake valve. Then, when the intake valve and the low-return valve overlap, air is sucked into the combustion chamber by the downward movement of the piston. Here, bombing loss is reduced by using the rotary hull to bring the air pressure downstream of the rotary hull to approximately atmospheric pressure at the initial stage of opening of the intake valve.

Furthermore, when the volume of the intake passage between the rotary hull and the intake valve is relatively large, a throttle valve is provided in the intake passage upstream of the rotary hull, although the effect of reducing pumping loss is reduced (S.A.E. paper 88038
(See Figure 9 of 8). Then, by throttling the air with a throttle valve and lowering the pressure in the intake passage below atmospheric pressure in advance, the combustion chamber pressure when the piston is at bottom dead center is set to, for example, -550 mm Hg during idling operation. I'm trying to make it possible.

Furthermore, Japanese Patent Application Laid-Open No. 148932/1984 is a device that includes a rotary hull upstream of the intake valve.

<Problems to be Solved by the Invention> However, in such conventional intake air control devices, a rotary valve is provided in series with the intake valve, so a gear is required to change the rotational phase of the rotary valve. Since it has a complicated structure in which multiple pieces are combined, there is a problem in that the friction loss is large and the overall effect of reducing pumping loss is reduced. Further, due to the complicated structure, it is difficult to control the intake air flow rate for each cylinder.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an intake air control device for an internal combustion engine that can highly accurately control the intake air flow rate for each cylinder while significantly reducing pumping loss with a simple configuration. With the goal.

<Means for Solving the Problems> For this reason, the present invention, as shown in FIG. Intake valve A of each cylinder
A first on-off valve D that opens and closes the intake passage C that communicates with the first on-off valve D, a communication passage E that communicates at least with the intake passage C downstream of each first on-off valve D, and a second on-off valve F that opens and closes the communication passage E, respectively. The intake air flow rate passing through the second on-off valve F is changed according to the opening and closing of the intake valve A,
Idle-up control means G for controlling the second on-off valve F to correct imbalance in output torque between cylinders during idle-up operating conditions in which the idle rotational speed of the engine is set higher than during normal idle operation; , a writing means I for writing the control result of the control means G during idle up into the storage means H, a retrieval means J for retrieving the control result from the storage means H during normal idle operation, and a retrieval means J for retrieving the control result from the storage means H during normal idle operation, A normal idle control means K for controlling each of the second on-off valves F is provided.

<Operation> In this way, by interposing the second on-off valve in parallel with the first on-off valve provided for each cylinder, bombing loss can be significantly reduced with a simple configuration, while the intake air flow rate for each cylinder can be reduced. was able to be controlled. Furthermore, control responsiveness can be improved by controlling the second on-off valve during normal idling operation based on the control results stored during idle-up operating conditions such as startup or warm-up.

<Example> An example of the present invention will be described below based on FIGS. 2 to 11. In the embodiment, a four-cylinder internal combustion engine will be described as an example.

In FIGS. 2 and 3, a butterfly-type throttle valve 2 as a first opening/closing valve that is linked to the depression of an accelerator pedal is arranged in series with an intake valve 3 in an intake passage 1 that is independent for each cylinder. Bypass passages 4 are respectively interposed and serve as communication passages that bypass each calibration valve 2. A second on-off valve 5 is interposed in each of the bypass passages 4, and the second on-off valve 5 is driven to open and close by an electromagnetic actuator 5A.

A control signal is input from the control device 6 to the actuator 5A. Here, the volume of the intake passage 1 from the throttle valve 2 to the intake valve 3 is set to about 2 of the maximum volume of the combustion chamber (combustion chamber volume when the piston is at the bottom dead center).

The control device 6 receives a reference signal (every 180 degrees in crank angle) and a position signal (for example, every 180 degrees in crank angle) from a crank angle sensor 7, and a signal embedded in the washer of the spark plug 8 of each cylinder. A cylinder pressure detection signal from a cylinder pressure sensor (not shown) is input.

The control device 6 operates according to the flowcharts shown in FIGS. 4 to 7, and outputs a control signal to the actuator 5A to control the opening and closing of the second on-off valve 5.

Here, the control device 6 constitutes a storage means (RAM), a writing means, and a retrieval means. In addition, the electromagnetic actuator 5
A and the control device 6 constitute an idle-up control means and a normal idle control means.

Note that 9 is a fuel injection valve.

Next, the process for Itake will be explained according to the flowcharts shown in FIGS. 4 to 7. Here, the routine shown in the flowcharts of FIGS. 4 and 7 is executed by an interrupt routine every time a reference signal is input from the crank angle sensor 7 as shown in FIG. ). Further, the routine shown in the flowchart in Fig. 5 is executed by an interrupt routine when the set crank angle (near the top dead center of #1 cylinder), which will be described later, is reached as shown in Fig. 8. (referred to as a crank job).

The routine shown in the flowchart of FIG. 6 is always executed when the interrupt routine is not executed.

First, the flowchart shown in FIG. 4 will be explained.

In S1, a set crank angle is set for executing the routine shown in the flowchart of FIG. As shown in FIG. 9, this set crank angle is set to a value near the top dead center immediately before the start of combustion of the air-fuel mixture (start of ignition) in the compression stroke of the #1 cylinder.

In S2, it is determined from the reference signal whether or not it is the #1 cylinder. If YES, the process proceeds to S3; if NO, the process proceeds to S6.

In S3, 1 is added to the variable counter value and the process proceeds to S4.

In S4, it is determined whether or not the added variable counter value has reached 3. If YES, the process proceeds to S5, and if NO, the process proceeds to S6.

In S5, the variable counter value is initialized to 0.

Therefore, the variable counter values are 0, 1, 2, 3.0,
1.2 is repeated, and the value is switched when the reference signal is input when the #1 cylinder is in the compression stroke.

In S6, the combustion chamber pressure read in the routine described later is
It is stored in a memory (RAM) at an address corresponding to the variable counter value for each cylinder. Therefore, for each cylinder,
Data of four combustion chamber pressures are stored in the memory as indicated by the broken line in FIG. Then, the combustion chamber pressure is sequentially rewritten from old data to new data.

In S7, the average combustion chamber pressure (indicated by the thin line in FIG. 10) is calculated by simply averaging the four pieces of data stored in the memory for each cylinder.

Next, to explain the flowcharts of FIGS. 5 and 6, in Sll of FIG. Read the combustion chamber pressure just before the start of combustion.

Here, the output torque of the engine is predicted from the combustion chamber pressure just before the start of combustion. Further, at 321 in FIG. 6, the engine rotational speed is read based on the manual cycle of the reference signal from the crank angle sensor 7.

Next, the flowchart shown in FIG. 7 will be explained.

In S31, it is determined whether the engine operating state is an idle-up operating condition. If YES (during idle-up operation), the process proceeds to S32; if NO (during normal idle), the process proceeds to 338. The idle amplifier operating condition is when the idle rotation speed immediately after starting or during warm-up is higher than during normal idle operation.

This is because combustion is essentially unstable during normal idling operation, and if data is sampled by adjusting the intake air flow rate for each cylinder, the data will vary between cylinders. If this is done, there is a risk of promoting instability, so the process proceeds to 332 when the idle-up operating condition is present.

Then, when the idle up operation condition is met, S3
2, the rotational difference NVAR between the engine rotational speed read in S21 and the target rotational speed is calculated.

In S33, a new rotation integral value is calculated by adding the previous rotation integral value to the calculated rotation difference NVAR. Further, NPI is calculated by adding an integral obtained by multiplying the newly obtained rotational integral value by a constant KlO and a proportional component obtained by multiplying the rotational difference NVAR by a constant Kll.

In S34, the total average combustion chamber pressure TOTALAVE is calculated by adding the average combustion chamber pressure of each cylinder calculated in S7 and then dividing it by the number of cylinders.

In S35, the total average combustion chamber pressure TOTA is determined for each cylinder.
The average combustion chamber pressure of the cylinder is subtracted from LAVE to calculate the deviation 'C Y L V A R. Furthermore, a new CYL integral value is calculated for each cylinder by adding the deviation CYLVAR calculated for each cylinder and the previous CYL integral value. Furthermore, by adding the integral obtained by multiplying the calculated CYL integral value by a constant K20 and the proportional component obtained by multiplying the deviation CYLVAR by a constant K21, CYLPT is calculated so that the output torque of all cylinders is approximately the same for each cylinder. Calculate so that

In S36, it is determined for each cylinder whether the combustion chamber pressure deviation CYLVAR calculated in S35 is less than or equal to a predetermined value.
If YES, it is determined that combustion is stable and S37
If the answer is NO, the process advances to S42.

In S37, the calculated CYLPI is stored in the RAM as a learning value CYLL in correspondence with the cylinder number.

On the other hand, during normal idling operation, at 338, the rotational difference NVAR is calculated in the same manner as S32.

In S39, similarly to S33 above, after calculating the rotational integral value, NPI is calculated.

In S40, as in S34, the total average combustion chamber pressure TOTALAVE of all cylinders is calculated based on the average combustion chamber pressure of each cylinder calculated in S7.

341, the total average combustion chamber pressure T calculated in S40
The deviation CYVAR is calculated for each cylinder by subtracting the average combustion chamber pressure of each cylinder from OTALAVE.

Furthermore, a new CYL integral value is calculated for each cylinder by adding the deviation CYLVAR calculated for each cylinder and the previous CYL integral value. Furthermore, the learned value CYLL is stored in the RAM.
is searched for each cylinder, and the searched learning value CYLL
CYLPI is calculated for each cylinder by adding the integral obtained by multiplying the calculated CYL integral value by a constant K30, and the proportional component obtained by multiplying the deviation CYLVAR by a constant K31. Here, the constants (gains) K30 and K31 are S3
Constant (gain) for calculating CYLPI in 5
It is set smaller than K20 and K21, so that CYLPI is set to be largely dependent on learned value CYLL.

In S42, CY calculated in S35 or S41
LP I and NP calculated in S32 or S38
A value obtained by multiplying I by a constant 40 is added to calculate the actuator control value for each cylinder.

Then, a control signal corresponding to the calculated control value is output to the actuator 5A of the corresponding cylinder, and the second on-off valve 5
The opening degree is controlled for each cylinder.

Changes in the opening degree of the second on-off valve 5 and changes in the intake pressure downstream of the throttle valve 2 during such control will be explained with reference to the time chart of FIG. 11. In addition, in this explanation, an example will be given when the throttle valve 2 is fully closed, that is, during idling operation, and in FIG. .

That is, at the start of the intake stroke when the intake valve 3 begins to open, the second on-off valve 5 is fully opened from the compression stroke to the explosion stroke so that the intake pressure downstream of the throttle valve 2 becomes atmospheric pressure. As a result, the intake pressure downstream of the throttle valve 2 is changed to the intake pressure (
This is the intake pressure at the end of the intake stroke, and increases from, for example, 550 to 570, H, to near atmospheric pressure during idling operation.

Here, if the second opening/closing valve 5 is always maintained at a constant opening and opened so that the intake pressure at the start of the intake stroke becomes atmospheric pressure, the intake pressure becomes as shown in A in Fig. 11, and the combustion chamber The intake air flow rate sucked into the unit becomes higher than the desired value. Also,
The intake pressure at the bottom dead center of the piston is 550 to 570, .
If the opening degree of the second on-off valve 5 is always set small so that Hg, the intake pressure at the start of the intake stroke will be B in Fig. 11.
The pressure does not reach atmospheric pressure as shown in .

Therefore, in this embodiment, as shown in FIG. 11, when the intake valve 3 opens, the second opening/closing valve 5 is driven to close from fully open to a predetermined opening. As a result, as shown in C in Fig. 11, the intake pressure at the time the intake valve 3 opens is set to near atmospheric pressure, the intake pressure at the end of the intake stroke is set to a predetermined value, and the intake air flow rate is set to the desired value. This allows it to be set to . Specifically, when the intake valve 3 closes, the second on-off valve 5 is fully opened, and immediately before the intake valve 3 opens, the second on-off valve 5 is closed to a predetermined opening degree.

By controlling the opening degree of the second on-off valve 5 in this manner, the opening degree of the second on-off valve 5 can be simply controlled in proportion to the engine rotation speed. This means that when the intake pressure at the start of the intake stroke is atmospheric pressure, the intake air flow rate can be determined from the ratio of the volume of the intake passage 1 downstream of the throttle valve 2 and the volume of the combustion chamber, which increases as the piston descends. This allows the shortfall to be reduced to the second
This is because it can be compensated for by controlling the opening degree of the on-off valve 5.

Here, in FIG. 11, the timing for switching the opening degree of the second on-off valve 5 is set before the start of the intake stroke (at the beginning of the exhaust stroke) to take into account the response delay of the control system. In reality, the second on-off valve 5 is switched to a predetermined opening degree when the intake valve 3 opens. In this way, the flow rate of intake air passing through the bypass passage 4 during the period when the intake valve 3 is closed becomes greater than during the period when the intake valve 3 is open. Incidentally, the intake air flow rate of the bypass passage 4 may be controlled as described above by controlling the actuator 5A using an on/off duty signal.

As explained above, the second on-off valve 5 is disposed for each cylinder in the high-pass passage 4 that passes through the throttle valve 2, and the volume of the intake passage 1 downstream of each throttle valve 2 is set to 172, which is the maximum volume of the combustion chamber.
and fully open the second on-off valve 5 so that the intake pressure downstream of the throttle valve 2 at the time the intake valve 3 opens is close to atmospheric pressure, and during the intake stroke, the second on-off valve 5 is opened to a predetermined opening degree. Since the valve is driven to close, the following effects can be obtained.

That is, when the intake valve 3 begins to open, the combustion chamber pressure (
Almost the same as the intake pressure in intake passage 1) Atmospheric pressure? As the piston descends, the combustion chamber pressure decreases approximately linearly from atmospheric pressure to the combustion chamber pressure at the bottom dead center position of the piston during idling operation (e.g. -550 to -570, ffiHg). do. Therefore, pumping loss can be significantly reduced compared to changes in intake pressure due to conventional throttle valve control alone, and period output can be maximized. In addition, the second on-off valve 5 of the high-pass passage 4 is operated by an electromagnetic actuator 5A.
Since the structure is controlled by , the structure can be simplified compared to the conventional one.

Here, the reason why the volume of the intake passage 1 from the throttle valve 2 to the intake valve 3 is set to 172 or less, which is the maximum volume of the combustion chamber, will be explained. Assume that the maximum volume of the combustion chamber is A, that the volume of the intake passage 1 from the throttle valve 2 to the intake valve 3 is B, that the compression ratio is 1/10, and that the piston bottom dead center during idling operation is Combustion chamber pressure (intake pressure) at -456■H
The explanation will be made assuming that the value is 9 (in a high-speed engine, the hull overlap period is long, so the value is about this value).

That is, the total volume of the intake passage 1 and the combustion chamber at the piston top dead center is (A/10+B), and the total volume of the intake passage 1 and the combustion chamber at the piston bottom dead center is (A
+B). Under such conditions, the atmospheric pressure (1 atm) decreases by -4
When the combustion chamber pressure and intake pressure change to 56,,H, (0.4 atm), (A/IO + B) / (A + B
) -0.4, and solving this gives A=2B.

Therefore, when the volume of the intake passage 1 is approximately 1/2 or less of the maximum volume of the combustion chamber, an optimum combustion chamber pressure at the piston bottom dead center position can be ensured during low load operation such as idling operation.

In addition, since the deviation (deviation) CYLVAR is calculated for each cylinder from the total average combustion chamber pressure TOTALAVE of all cylinders, the combustion chamber pressure of each cylinder approaches the total average combustion chamber pressure TOTALAVE. Combustion chamber pressure can be made almost the same in all cylinders. This makes it possible to make the output torque of all cylinders substantially the same, thereby stabilizing the drivability during idling operation. Further, after determining the rotational difference (deviation) NVAR of the engine rotational speed of each cylinder from the target rotational speed, NPI is determined for each cylinder, and the NPI that depends on the engine rotational speed is added to the control value of the actuator 5A. This makes it possible to make the engine rotational speeds of all cylinders substantially the same, which also makes it possible to stabilize the drivability during idling operation.

In addition, since the control value of the actuator 5A is determined for each combustion stroke (reference signal) in each cylinder, the output torque and engine rotation speed can be made almost the same in each cylinder, which also makes it possible to maintain the same output torque and engine speed during idling. drivability can be stabilized.

Furthermore, during idle-up operating conditions, the CYPI set based on the combustion chamber pressure (intake pressure) is memorized, and based on the memorized CYPI, CYLPI is calculated during normal idle operation to obtain the control value. So,
Even if changes occur over time in the second on-off valve 5 or the like in each cylinder, the intake air flow rate can be controlled with high precision while improving the control responsiveness of the second on-off valve 5. In addition, the CYLPI stored in the RAM during idle-up operation is set so that the output torque of all cylinders is approximately the same based on the deviation CYLVAR from the total average combustion chamber pressure of all cylinders TOTALAVE. During idling operation, imbalance in output torque between cylinders can be eliminated with good control response, and idling stability can be improved.

In the example, the output torque of the engine was predicted from the combustion chamber pressure, but the intake pressure, intake air flow rate,
The second on-off valve may be controlled based on the air-fuel ratio of the engine (for example, a detection signal from an oxygen sensor that detects the air-fuel ratio based on the oxygen concentration in the exhaust gas) or the actual output torque. In addition, a second on-off valve is interposed in the bypass passage that bypasses the throttle valve. An on-off valve may be provided.

Effects of the Invention> As explained above, the present invention has a structure in which the second on-off valve 5 is interposed in the communication passage communicating with the intake passage downstream of the first on-off valve provided for each cylinder. With this configuration, bombing loss can be significantly reduced and output torque can be improved, and the intake air flow rate can be controlled for each cylinder. In addition, the control results of the second on-off valve set during idle-up operation are stored, and the second on-off valve is controlled during normal idle operation based on the stored control results, so there is no change over time. Since the second on-off valve can also be controlled while improving its control response, the intake air flow rate can be controlled with high precision and idling stability can be improved.

[Brief explanation of drawings]

FIG. 1 is a diagram corresponding to the claims of the present invention, FIG. 2 is a configuration diagram showing a first embodiment of the present invention, FIG. 3 is an enlarged view of the main parts of the same, and FIGS. 4 to 7 are flowcharts of the same, Figures 8 to 11
The figure is an explanatory diagram of the same operation. 1... Intake passage 2... Throttle valve 3... Intake valve 4... Bypass passage 5... Second on-off valve 5A
...Actuator 6...Control device

Claims (1)

[Claims] In an internal combustion engine in which an intake valve is opened when a piston descends to draw air into a combustion chamber, a first opening/closing valve is provided for each cylinder and opens/closes an intake passage communicating with the intake valve of each cylinder, and a first opening/closing valve for each cylinder is provided for each cylinder. a communication passage that communicates at least with the intake passage downstream of the valve; a second on-off valve that opens and closes the communication passage, respectively;
an idle-up operation in which the intake air flow rate passing through the second on-off valve is changed according to the opening and closing of the intake valve, and the idle rotation speed of the engine is set higher than during normal idle operation. an idle-up control means for controlling the second on-off valve to correct an imbalance of output torque between the cylinders when the condition is met; a writing means for writing a control result of the idle-up control means into a storage means; An internal combustion engine characterized by comprising: a retrieval means for retrieving control results from the storage means during idling operation; and a normal idling control means for controlling each of the second on-off valves based on the retrieved control results. intake air control device.