JPH0443847A - Air supply device for internal combustion engine - Google Patents

Abstract

PURPOSE:To make generated torque to respective cylinders uniform and prevent generation of engine vibration or surging phenomenon by correcting valve opening time set through a valve opening time setting means at every control valve according to difference between rotating speed of each cylinder and mean value of rotating speed of all cylinders. CONSTITUTION:A valve opening time setting means l sets the valve opening time of a control valve 5 according to an engine operating condition. The set valve opening time is in same value to each control valve. A rotating speed detecting means 2 detects rotating speed of each cylinder from the top dead center of compression stroke to the bottom dead center of expansion stroke, and outputs to a mean rotating speed computing means 3 and a correcting means 4. The mean rotating speed computing means 3 computes the mean rotating speed of all cylinders, and outputs to the correcting means 4. The correcting means 4 corrects the valve opening time set by the valve opening time setting means l at every control valve 5 according to deviation between the input mean rotating speed and the rotating speed of each cylinder, and supply air quantity is adjusted at every cylinder.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention has a shutoff valve and a bypass intake passage for each intake pipe of each cylinder, and closes the shutoff valve during low load such as idling to shut off the intake air of each cylinder. The present invention relates to an air supply device for an internal combustion engine that employs a method (hereinafter referred to as an intake boat filling method) of filling air into an intake pipe portion downstream of a shutoff valve by opening and closing a control valve of a bypass intake passage during a valve closing period.

[Conventional technology]

Generally, in a conventional internal combustion engine having a throttle valve, the throttle valve is substantially fully closed during idling, and the intake pipe pressure on the downstream side of the throttle valve largely shifts to the negative pressure side. Normally, there is a valve overlap period between the opening period of the intake valve and exhaust valve of each cylinder. Immediately after the intake valve opens, the exhaust valve is not closed and the exhaust pipe and cylinder The combustion gas inside the cylinder flows back through the intake valve to the intake port, which is under negative pressure, and the proportion of residual combustion gas in the fresh air supplied into the cylinder increases. As a result, combustion within the cylinder becomes unstable, causing misfires and the like. Furthermore, in this state, the negative pressure in the intake pipe is large, which increases the pumping loss of the engine, which is also a factor in reducing engine efficiency.

In order to solve the above-mentioned problem, the applicant of the present application proposed an air supply system for an internal combustion engine using the above-mentioned intake port filling method.
It is proposed in No.-43976.

In the above air supply system, a cutoff valve is provided in the intake passage of each cylinder of the engine, and when the engine is idling, this cutoff valve is fully closed, and a bypass intake passage is provided that communicates the intake pipes on the upstream and downstream sides of the cutoff valve. The intake port is filled with air by opening and closing the control valve. That is, in the above device, the control valve of the bypass intake passage is opened for a predetermined period while the intake valve is closed, the intake port pressure is increased to near atmospheric pressure, and the control valve is closed before the intake valve is opened. The air required for engine operation is supplied by air filled in the intake pipe downstream of the shutoff valve. This prevents the intake boat pressure at the beginning of the intake valve opening from becoming a large negative pressure unlike in conventional internal combustion engines, and furthermore, while the intake valve is open, the intake pipe is closed to the shutoff valve and control valve. Because it is completely closed by
Even if combustion gas backflows from the cylinder, the pressure inside the intake pipe on the downstream side of the shutoff valve increases, and further backflow of combustion gas can be prevented. Therefore, the amount of combustion gas flowing back into the intake pipe is reduced, and the combustion condition is improved. Additionally, by increasing or decreasing the opening time of the control valve, the amount of air filled into the intake pipe downstream of the shutoff valve can be changed and the amount of air supplied to the cylinder can be adjusted, making it possible to precisely control the engine speed during idling. It becomes.

[Problem to be solved by the invention]

In the device described in the above-mentioned Utility Application No. 1-43976, the torque generated in each cylinder is made uniform by making the control valve opening time the same for each cylinder so that the amount of air supplied to each cylinder is equal. Trying to.

However, in reality, the flow rate when each control valve opens varies within the flow tolerance of the control valve, and leakage when the shutoff valve is fully closed also differs for each cylinder, so the control valve opening time varies. If they are made the same, the amount of air supplied to each cylinder will not be the same. Furthermore, since the combustion state within the cylinders varies slightly from cylinder to cylinder, even if the amount of air supplied is the same, the torque generated by each cylinder cannot be made uniform. Furthermore, the amount of leakage from the above-mentioned shutoff valve and the combustion state within the cylinder may change over time due to the accumulation of dirt and the like. For this reason, in the above method, even if substantially uniform torque is obtained at first, the torque generated in each cylinder may become non-uniform as time passes.

When there is variation in the torque generated by each cylinder, uneven rotation causes excessive engine vibration during idling, and when the vehicle is running at extremely low loads, longitudinal vibration of the vehicle, known as a surge phenomenon, occurs, which significantly worsens the driving sensation. may occur.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an air supply device for an internal combustion engine that can evenly generate torque to each cylinder in the intake boat filling method and prevent engine vibration and surge phenomena from occurring.

[Means to solve the problem]

According to the present invention, as shown in the configuration diagram of the invention in FIG. 1, each intake pipe of each cylinder includes a cutoff valve and a bypass intake passage that communicates between the upstream side and the downstream side of the cutoff valve of each intake pipe. , a control valve 5 for opening and closing the bypass intake passage, and a valve-opening time setting means 1 for setting the valve-opening time of the control valve 5 according to the engine operating state. , a rotational speed detection means 2 for detecting the crankshaft rotational speed during the explosion stroke of each cylinder, and an average rotational speed calculation means 3 for calculating an average value for all cylinders of the rotational speed of each cylinder detected by the rotational speed detection means. , comprising a correction means 4 for correcting the valve opening time set by the valve opening time setting means 1 for each control valve according to the difference between the rotational speed of each cylinder and the average value of rotational speeds of all cylinders. An air supply device for an internal combustion engine, characterized by:

[For production]

The valve opening time setting means 1 sets the valve opening time of the control valve 5 according to the engine operating state. The set valve opening time is the same value for each control valve. The rotational speed detection means 2 detects the rotational speed of each cylinder during the period from the top dead center of the compression stroke to the bottom dead center of the expansion stroke, and outputs it to the average rotational speed calculation means 3 and the correction means 4. The average rotational speed calculation means 3 calculates the average rotational speed of all cylinders and outputs it to the correction means 4.

The correction means 4 corrects the control valve opening time set by the valve opening time setting means 1 for each control valve 5 according to the deviation between the input average rotational speed and the rotational speed of each cylinder, and adjusts the control valve opening time for each cylinder. Adjust the supply air amount.

〔Example〕

Fig. 2 shows an example of an air supply system for an internal combustion engine (intake port filling engine) using the intake boat filling method for carrying out the main air flow.
2 is a cylinder head, 13 is a piston, 14 is a combustion chamber,
15 is an intake port, 16 is an exhaust port, 17 is an intake valve,
18 is an exhaust valve, 19 is an intake pipe forming a main intake passage for each cylinder, and 20 is a surge tank.

A cutoff valve 21 is provided in the intake pipe 19 of each cylinder, and in this embodiment, the cutoff valve 21 also serves as a throttle valve.
At low/medium loads or above, the accelerator pedal operated by the driver opens the required amount to steplessly adjust the flow rate of intake air flowing from the surge tank 20 to the intake port 15. However, in the idling state, the cutoff valve 21 is fully closed, essentially blocking airflow. However, in other embodiments, the isolation valve 21 may simply be in the fully open position.
A throttle valve operated by the driver may be provided in the intake pipe or the like common to all cylinders. In addition, 22
23 indicates an ignition plug, and 23 indicates a fuel injection valve.

24 is an intake boat 15 so as to bypass the shutoff valve 21.
This is a sub-intake pipe that connects the surge tank 20 and the bypass intake passage to form a bypass intake passage, and is provided for each cylinder.A control valve 25, which is a solenoid valve in this embodiment, is provided in a part of the passage. It is designed to interrupt the airflow flowing through the intake passage. The control valve 25 is an electronic control unit (ECU) 2
The ECTL 26 consists of a digital computer with ROM 2g, RAM 29, and CPI connected to each other by a bidirectional bus 27.
It is equipped with an I3Q, an input port 31, and an output port 32.

The ECU 26 performs various controls for engine operation in addition to controlling the opening and closing of the control valve 25.
Engine cooling water temperature, battery voltage, generator load, etc. are input from each sensor, and the air conditioner is turned on/off.
An off signal is being input.

In addition, a crank rotation angle sensor 33 is installed in the distributor (not shown), and in addition to generating 8 engine rotation pulses Ne every 30 degrees of crank angle rotation, it also outputs a reference pulse G1 and a piston of each cylinder every 720 degrees of crank rotation angle. When the CPII 3 reaches the top dead center of the compression stroke, a cylinder discrimination pulse G is output, and the CPII 3
There is 0 manpower. This example shows a four-cylinder internal combustion engine, and the cylinder discrimination pulse G is a crank rotation angle of 180.
output every time.

(See Fig. 4) In addition, in this embodiment, each cutoff valve 21 has an opening sensor 38.
is provided, and outputs a signal when the shutoff valve 21 is fully open, that is, when the engine is in an idling state. Further, 36 is an intake pipe pressure sensor provided downstream of the cutoff valve 21 of each intake pipe, and inputs the pressure of the intake boat 15 of each intake pipe to the manual port 31. Also,
ECL: 26 is output port 32 or drive circuit 34.35
The control valve 25 and the fuel injection valve 23 are driven and controlled via the control valve 25 and the fuel injection valve 23.

FIG. 3 is a diagram showing the conventional opening/closing timing of the control valve 25, intake valve 17, and exhaust valve 18. As shown in the figure, the control valve 25 is controlled to open after the intake valve 17 is closed, and to close before the opening recovery intake valve 17 opens for a predetermined period of time. Here, the opening time of the control valve is determined by the ECU 26 as described later.
Therefore, each cylinder is controlled to the same value depending on the engine load, rotation speed, etc. FIG. 8 shows pressure changes in each intake port 15 when the control valves are controlled to open and close as described above.

When the engine is idling, the shutoff valve 21 is fully closed, and the intake port 15 is a substantially sealed space. Therefore, as shown in FIG. 8, immediately after the intake valve 17 is closed, the intake port 15 is under negative pressure due to the intake stroke of the cylinder (section 2 in FIG. 8). When the control valve 25 is opened in this state, the amount of air necessary for idling flows from the auxiliary intake pipe 24 to the intake port 15, and the pressure at the intake port 15 is determined by the opening time of the control valve 25, which is near atmospheric pressure. Increases to pressure (section ■)
. Even after the control valve 25 closes, the intake port 15 pressure gradually increases due to air flowing in due to leakage of the shutoff valve 21, etc. (section ■). Next, when the intake valve 17 opens, the intake port pressure temporarily increases due to the backflow of combustion gas from the cylinder (section ■), but since the pressure at the intake port 15 has risen to near atmospheric pressure, the combustion gas flows backflow. The amount of gas is less than before. Next, when the piston enters the downward stroke, intake port 1
The air of No. 5 is sucked into the cylinder, and the intake port pressure does not decrease (section (2)), and is maintained at negative pressure even after the intake valve is closed (section (2)). In this way, by increasing the intake port pressure to near atmospheric pressure before opening the intake valve, it is possible to reduce the amount of combustion gas flowing back and increase the cylinder scavenging efficiency.

However, if the opening time of the control valve 25 is controlled to be the same for each cylinder as described above, although the scavenging efficiency is improved, the intake air amount of each cylinder will vary. This is because, as described above, there are differences in the flow rate tolerance of each control valve 25 and the amount of leakage when the cutoff valve 21 is fully closed.

Therefore, the difference in intake air amount causes a difference in the torque generated in each cylinder. Further, since the combustion conditions in each cylinder are originally slightly different due to manufacturing tolerances, it is impossible to completely equalize the generated torque even if the intake air amount is made equal in each cylinder.

For this reason, when the difference in the amount of intake air is added, the variation in the generated torque increases, causing uneven rotation of the engine.

In this example, the engine rotation speed when each cylinder is in the explosion stroke is measured for each cylinder, and the average value is calculated, and the rotation speed of each cylinder during the explosion stroke and the average rotation speed of all cylinders calculated as above. By correcting the opening time of each control valve according to the deviation from the engine speed, the rotational speed of each cylinder during the explosion stroke is made equal. In other words, if the rotation speed of a certain cylinder is lower than the average rotation speed, the control valve opening time is extended, the amount of intake air to that cylinder is increased, and the amount of fuel injection is also increased according to the amount of intake air. By doing so, the torque generated in that cylinder is increased and the rotational speed is increased. Furthermore, if the rotation speed is higher than the average rotation speed, the opposite operation is performed.

Next, the specific control operation of EC[I 26 in the above control will be explained using FIG. 5 and FIG. 6.

FIG. 5 is a flowchart showing the operation for determining the valve opening time correction amount for each control valve 25.

In this embodiment, this control is performed as a routine every 180 degrees of crank rotation angle, and the G
Executed every time a pulse signal is input. As shown in FIG. 4, three types of pulses, Ne, G, and G, are transmitted from the crank rotation angle sensor 33. Pulse G is emitted when either cylinder is at the top dead center of the compression stroke, and in this embodiment is emitted every 180 degrees. Further, the pulse Ne is transmitted every 30 degrees of the crank rotation angle, and is transmitted at the same time as the pulse G every 6 pulses. In addition, the G1 pulse is generated when the engine first ring is at the top dead center of the compression stroke, that is, the G1 pulse
is transmitted simultaneously with pulse G every four pulses.

In FIG. 5, when pulse G is input, the routine starts at step 100 and proceeds to step 110.

Steps 110 to 130 are steps for determining which cylinder is currently at the top dead center of the compression stroke.In step 110, it is determined whether pulse G1 is input together with pulse G, and if G+ is input, determines that the first cylinder is at the top dead center of the compression stroke, proceeds to step 120, and sets flag X representing the cylinder number to X=1. If G1 has not been input, the process proceeds to step 130, and the value obtained by adding 1 to the value of X at the previous execution is set as X. Here, X=1.2, 3.4 represent the first, third, fourth, and second cylinders, respectively, according to the firing order of the cylinders. When the cylinder discrimination is completed in steps 110 to 130, the rotational speed (number of revolutions) N (rpm) is calculated in step 140. The rotation speed is calculated from the time required from the top dead center of the cylinder compression stroke to the bottom dead center of the expansion stroke (corresponding to a crank angle of 180 degrees).
It is calculated from the time until the second pulse Ne is input. When the rotation speed N is calculated in step 140, in step 150, the rotation speed is converted to the rotation speed NX of the cylinder determined in steps 110 to 130 and stored in the RAM of EC[I 26.
29 to be memorized. That is, the latest rotational speeds N1 to N4 of each cylinder are constantly updated and stored in the RAM 29. Next, in step 160, the RAM
The average rotational speed Nave is calculated by averaging the rotational speeds N1 to N4 stored in 29.

From step 170 to step 200, the above average rotation speed N
This step is to obtain a correction amount CTACX for the control valve opening time from ave and NX obtained in step 150.

In step 170 and step 190, NX and Nav+a
It is determined whether the difference between the
If the rotational speed is less than the rpm, it is considered that the rotational irregularity is within the allowable range, and the routine is terminated without making any changes to the CTACX set during the previous execution. If in step 170 NX is lower than NyuV by 10 rpm or more, in step 180 the correction amount CTACX for the X cylinder is increased by 0.3%. At this time, if only the control valve opening time of the X cylinder is increased, the average rotation speed may rise due to the increase in the torque of the X cylinder. Therefore, in order to maintain the average rotation speed constant, the Correction amount CTAC (X+1) for control valve opening time of cylinders other than cylinders ~CTAC
(X+3) are each reduced by 0.1% so that the correction amount change becomes zero as a whole. Since the change in the amount of correction for each cylinder is 0.3% at most, this prevents sudden changes in rotation and overshoots due to excessive amounts of correction. Step 200 shows correction when NX exceeds Nave by more than 1Q rpm. Contrary to step 180, CTACX is shortened by 0.3%, and the correction amounts for the other cylinders are increased by 0.1%.

As described above, the control valve opening time correction amount CTACX of each cylinder can be adjusted according to the rotational speed of each crank.

FIG. 6 shows a control execution routine in which the control valve is opened using the CTA (:X) obtained above.

In this routine, fuel injection control (steps 320 to 360)
) and control valve opening operation (steps 370 to 420)
) at the same time.

This routine is performed every 180 degrees of crank rotation angle, and starts 60 degrees after the top dead center of each cylinder's intake stroke.

In FIG. 6, the routine begins at step 310.
Then, the cylinder number χ which is currently 60 degrees after the top dead center of the intake stroke
is determined. This cylinder number determination is performed by counting pulses G and pulses G1 in the same manner as steps 110 to 130 in FIG. When the cylinder is determined in step 310, the intake pipe pressures P and x of the crank are read out in step 320 using the cylinder number χ determined above. (Intake pipe pressure P, The value is stored in the RAM 29 and used. That is, P and X are the intake boat pressures when the X number ring is at the bottom dead center of the intake stroke immediately before starting execution of this routine.

Next, in step 330, the basic fuel injection time T, is determined from the map stored in R[]M 28 using the rotational speed NX of the X number ring obtained in the routine of FIG. Set. Further, in step 340, the injection time TA is determined by multiplying the above T by a correction coefficient β depending on the engine operating conditions. Here, β is read from a map stored in the ROM 28 based on the cooling water temperature, intake air temperature, load on auxiliary equipment, etc. Step 350 is a final step for setting the injection time of the fuel injection valve of each crank, and the injection time of the cylinders X+1 to X+3, which do not perform fuel injection during the current execution, is set to zero. Next, in step 350, the injection time TAu Since fuel injection is performed at a time when the intake pipe negative pressure is large at the beginning of the opening of the control valve, the fuel is atomized well.

Next, steps 370 to 420 will be explained.

In step 370, the basic valve opening time T of the control valve is determined. settings are made. To is the cooling water temperature Tyo1, and the battery voltage B
, generator load E, air conditioner on/off to R[1M
The time ToTy determined using the map built into 28
It is determined as the sum of w, ToB, ToE, and ToAc, and is common to all cylinders. Once To is set, it is then determined in step 380 whether the engine is in an idling state. This determination is made by the opening sensor 3 of each shutoff valve 21.
The determination is made based on the presence or absence of the output of 8.

When it is determined in step 380 that the engine is in an idling state, the process proceeds to step 390, where T is set for idle speed control. A correction coefficient α is added to .

Idle speed control is an operation for maintaining the idle speed at a set speed, and the correction coefficient α is set according to the difference between the set speed and the actual engine speed.

If it is determined in step 380 that the engine is not idling, then T in step 400. ni-ritsu ni 5cns
is added.

Next, in step 410, the control valve opening time TA of each intake pipe is
C is set. In this case, the valve opening time TACX of the control valve of the No. The control valve opening times TACX+1 to TACX+3 of the cylinders similar to those in step 350 are set to zero, so that only the control valve of the X cylinder is opened, and then in step 420 T in the drive circuit. Outputs X and ends the routine.

In this embodiment, the basic fuel injection time T, is the intake port pressure P,
The reason why the intake boat pressure 9X at the intake bottom dead center of each cylinder is set by X and the rotational speed NX changes depending on the amount of air filled into the intake boat through the control valve 25 before the start of the intake stroke. This is because the intake air amount of each cylinder can be known from P and X. As a result, in this embodiment, the amount of intake air is corrected according to the rotation speed of the explosion stroke of each cylinder, and even if the amount of intake air varies between cylinders, this correction allows the fuel injection of each cylinder to be adjusted. The amount is adjusted according to the amount of intake air, and the air-fuel ratio of each cylinder is kept constant.

By performing the above control, the control valve opening time is corrected for each explosion stroke of each cylinder, and the torque generated in all the cylinders is adjusted uniformly after a certain period of time has passed after the start of the engine. Additionally, in the above embodiment, in addition to the RAM 29 of the ECU 26, there is also a backup R that can retain memory even during the period when the engine is stopped.
AM 29 is set as the control valve opening time correction amount C for each cylinder.
By performing learning control in which the latest value of TAc is constantly updated and stored, it is possible to equalize the torque generated in each cylinder from the time the engine is started.

Next, FIG. 7 shows another embodiment of the present invention.

In the above embodiment, the control valve opening time is corrected based on the difference between the rotation speed of each cylinder and the average rotation speed, not only when the engine is idling but also when running at low load. When the vehicle is running, the running torque constantly fluctuates because the road surface conditions (unevenness, coefficient of friction, etc.) are not constant.

Therefore, even if the torque generated by each cylinder of the engine is uniform when the vehicle is running under low load, the engine speed is not necessarily constant due to load fluctuations.

Therefore, if control is performed based on the above-mentioned difference in cylinder rotation speed during low-load running, the control valve opening time correction amount CTAC of each cylinder will not converge to a constant value and the torque generated by each cylinder will not be equalized. There is a risk that it will not be possible. Therefore, in this embodiment, the control valve opening time correction based on the difference in the rotational speed of each cylinder is stopped only during idling, and under conditions other than idling, the engine speed and load are The control valve opening time is corrected using a correction amount ΔT set in advance for each cylinder based on the above.

7 shows control steps corresponding to steps 370 to 420 in FIG. 6, and as shown in FIG. 6, after the fuel injection execution routine (steps 310 to 350 in FIG. 6), You can run it,
The control routine may be executed as a separate control routine from the fuel injection every 180 degrees of the rank rotation angle.

In this embodiment, in steps 510 and 520 as in steps 370 and 380 in FIG.
. setting and determination of idling are performed, and if it is determined that it is in the idling state, step 390 in FIG.
．． Similar to step 410, idle speed control (step 53
0) and each cylinder rotation speed difference (step 54)
0) is performed to set the control valve opening TACX. However, if it is determined in step 520 that the engine is not in an idling state, the intake pipe pressure Pave of each cylinder is calculated in step 550, and the average value Nave and Pave of the rotational speed of each cylinder is calculated in step 560. The correction amount ΔT is read from the map stored in the ROM 28, and the valve opening time TACX is set to T in step 570. It is set as the sum of and ΔT.

The above correction amount ΔT is calculated by actually driving the vehicle on a flat road where road surface conditions do not change or on a chassis dynamo at the time of shipment from the factory after the vehicle is completed, and while changing the engine load and rotation speed.
The control shown in FIG. 6 and FIG. 6 is carried out, and the correction amount CTAC determined for each cylinder is used as a function (map) of the engine load and rotation speed stored in the backup RAM. In other words, in this embodiment, no correction is made based on the difference in rotational speed of each cylinder except during idling, and the engine load and rotational speed are calculated for each cylinder based on the results of control actually performed without the influence of road surface conditions at the time of shipment from the factory. It is stored as a function of numbers, and the results are used for control. Therefore, in this embodiment, even during low-load running, the torque generated by each cylinder can be reliably equalized without being affected by road surface conditions.

In this example, the average value of each cylinder intake pipe pressure is used as the engine load because of the six-cylinder setting, but in addition to the intake pipe pressure, throttle opening, fuel injection amount, etc. are also used as representative values of the engine load. It's okay.

〔Effect of the invention〕

As described above, according to the present invention, the rotation speed of each cylinder during the explosion stroke is measured, and the opening time of the control valve is corrected for each ring according to the difference from the average rotation speed. By equalizing the generated torque during the explosion stroke, engine vibration during idling can be reduced, and surges can be prevented during low-load running.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a schematic diagram showing an embodiment of the present invention, and FIG. 3 shows a control valve and an intake valve,
Figure 4 is a diagram showing the opening/closing timing of the exhaust valve, Figure 4 is a diagram showing the angle signal sent from the crank rotation angle sensor, Figures 5 and 6 are flowcharts showing control of the opening time of the control valve, and Figure 7 is a diagram showing the angle signal transmitted from the crank rotation angle sensor. FIG. 6 is a flow chart showing another embodiment of the control shown in FIG. 6, and FIG. 8 is a diagram showing changes in the intake boat pressure of each cylinder. 15... Intake boat, 17... Intake valve, 21...
...Shutoff valve, 23...Fuel injection valve, 25...
- Control valve, 26...ECU, 33...Crank rotation angle sensor, 36...Intake pipe pressure sensor.

Claims (1)

[Scope of Claims] 1. For each intake pipe of each cylinder, a shutoff valve, a bypass intake passage communicating with an upstream side and a downstream side of the shutoff valve of each intake pipe, and control for opening and closing the bypass intake passage. In an air supply system for an internal combustion engine, the air supply device for an internal combustion engine is provided with a valve-opening time setting means for setting a valve-opening time of the control valve according to an engine operating state, and a crankshaft rotational speed during an explosion stroke of each cylinder. a rotational speed detection means for detecting, an average rotational speed calculation means for calculating an all-cylinder average value of the rotational speed of each cylinder detected by the rotational speed detection means, and an all-cylinder average of the rotational speed of each cylinder and the rotational speed. An air supply device for an internal combustion engine, comprising: a correction means for correcting the valve-opening time set by the valve-opening time setting means for each control valve according to the difference between the valve-opening time setting means and the valve-opening time setting means.