JP2004183541A - Intake air flow control system of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an intake air flow control system for an internal combustion engine capable of preventing cost increases without having any adverse effect upon the startability of the internal combustion engine. <P>SOLUTION: This control device is structured so as to take a step S5 for using a valve opening corresponding to a reference intake air flow on a reference characteristic in place of a valve opening corresponding to a calculation intake amount when such a first re-reading condition that an absolute value of a difference between a target idling speed and a present idling speed is smaller than a first threshold value and such a second re-reading condition that an absolute value of a difference between a calculated intake air flow and a reference intake air flow is larger than a second threshold value are satisfied, in aligning the reference position of an auxiliary intake air flow control valve. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an intake air flow control device for an internal combustion engine, and more particularly to an intake air flow control device for an internal combustion engine that can prevent cost increase and prevent adverse effects on starting characteristics.
[0002]
[Prior art]
2. Description of the Related Art As an intake flow control device for an internal combustion engine of this type, an intake flow control device which bypasses a throttle valve and has an auxiliary intake passage having an intake control valve is generally known. According to the intake air flow control device, by controlling the opening degree of the intake control valve during idling, the auxiliary intake air flow flowing through the auxiliary intake passage is adjusted, and the engine speed is reduced to the target idle speed. Can be matched.
[0003]
For example, a stepping motor is used for opening and closing the intake control valve. The valve opening when the step motor is adjusted to the reference position is stored in the memory of the electronic control unit (ECU), and by increasing or decreasing the command value for the reference position, an arbitrary valve opening can be obtained. It becomes possible.
The ECU determines the target valve opening of the intake control valve (that is, the target auxiliary intake flow rate) by detecting the engine speed and the like, and calculates the command value to be supplied to the step motor accordingly. . However, the valve opening may deviate due to aging of the step motor or the like.
[0004]
In order to eliminate such a deviation, the reference position is periodically adjusted, that is, the reference position for forcibly matching the valve opening of the intake valve control recognized by the ECU with the actual valve opening is performed. There is a need.
For that purpose, in Patent Document 1 below, immediately after the ignition switch is turned off, the step motor is energized to move the intake control valve to the fully closed position or the fully open position, and that valve position is used as a reference position for valve control. Has been proposed.
Further, Japanese Patent Application Laid-Open No. H11-163873 proposes that the intake control valve is moved to a half-open position after the engine is stopped, and that the valve position is used as a reference position for valve control.
[0005]
[Patent Document 1]
JP-B-63-42106
[Patent Document 2]
JP-A-6-307267
[0006]
[Problems to be solved by the invention]
However, in both of Patent Documents 1 and 2, since the step motor must be operated when the engine is stopped, a drive circuit for backing up the operation power supply of the ECU is required, and complete discharge of the battery, that is, a so-called battery A function such as a timer circuit for preventing rising is required. As a result, there is a problem that the circuit configuration is complicated and the cost is increased.
[0007]
In order to avoid this, it is conceivable to perform the reference position adjustment of the intake control valve immediately after the engine is started. In this case, for example, if the fully closed position is set as the reference position, poor start-up (start time Is long, the engine stalls after startup, etc.). Further, if the fully open position is set as the reference position, the intake air flow rate becomes excessively large, resulting in engine malfunction.
[0008]
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 flow control device for an internal combustion engine that can prevent an increase in cost and does not adversely affect the starting characteristics of the internal combustion engine.
[0009]
[Means for Solving the Problems]
The present invention employs the following means in order to solve the above problems.
That is, the intake air flow control device for an internal combustion engine according to the first aspect flows through the auxiliary intake passage that is driven by a step motor and the auxiliary intake passage that bypasses a throttle valve provided in the main intake passage. An auxiliary intake flow rate control valve that controls an auxiliary intake flow rate, and an intake flow rate control device that stores a valve opening degree of the auxiliary intake flow rate control valve and a reference characteristic between the auxiliary intake flow rates in advance.
When idling,
A first read condition in which an absolute value of a difference between the target idling rotational speed and the current idling rotational speed is smaller than a first threshold value;
The absolute value of the difference between the calculated intake flow rate when the auxiliary intake flow rate for obtaining the target idling speed is obtained by calculation and the reference intake flow rate when calculated based on the reference characteristics is the second. And a second replacement condition that is larger than the threshold value of
When the first read condition and the second read condition are compatible, the valve opening corresponding to the reference intake flow rate is used along the reference characteristic instead of the valve opening corresponding to the calculated intake flow rate. A reading process is performed.
[0010]
According to the intake air flow control device for an internal combustion engine according to the first aspect, when the first replacement condition is satisfied, it is determined that the current idling rotational speed approaches the target idling rotational speed. When the second read condition is satisfied, it is determined that the auxiliary intake air flow control valve is displaced and needs to be corrected. When the first read condition and the second read condition are compatible, the valve opening corresponding to the reference intake flow is more correct than the valve opening corresponding to the calculated intake flow.
[0011]
An intake valve control device for an internal combustion engine according to claim 2, further comprising an auxiliary intake passage that bypasses a throttle valve in an intake system of the internal combustion engine, and that is connected to a step motor to open and close the auxiliary intake passage. In an intake valve control device for an internal combustion engine having a flow control valve, the reference position of the step motor is read when the current idling speed approaches a target idling speed.
[0012]
According to the second aspect of the present invention, the reference position of the stepping motor is replaced when the current idling speed approaches the target idling speed.
[0013]
The intake valve control device for an internal combustion engine according to claim 3, further comprising an auxiliary intake passage that bypasses a throttle valve in an intake system of the internal combustion engine, and that is connected to a step motor to open and close the auxiliary intake passage. In an intake valve control device for an internal combustion engine equipped with a flow control valve, a means for determining whether or not the engine is currently idling and, when it is determined that the engine is currently idling, rewriting the reference position of the step motor And means for performing the operation.
[0014]
According to the third aspect of the present invention, when it is determined that the vehicle is idling at present, the reference position of the stepping motor is read.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
One embodiment of an intake flow control device for an internal combustion engine according to the present invention will be described below with reference to the drawings. However, it is needless to say that the present invention is not limited to this. Note that, in the present embodiment, a case where the present invention is applied to a motorcycle will be described as an example, but it is needless to say that the present invention may be applied to other vehicles.
[0016]
As shown in FIGS. 1 and 2, the motorcycle 1 of the present embodiment is configured as a scooter type in which a power unit 4 is disposed immediately below a luggage box 3 that is long in the front-rear direction while using a tandem seat type seat 2 as a lid. Have been. The power unit 4 is a continuously variable transmission 8 that integrally connects an engine (internal combustion engine) 5 in which a cylinder block 6 is largely inclined forward and a transmission case 10 extending rearward to one side of a crankcase 9 of the engine 5. A rear wheel (drive wheel) 11 is pivotally supported at the rear end of the transmission case 10.
[0017]
As shown in FIG. 2, a cylinder head 7 joined to the front end of the cylinder block 6 has an intake port 7a having an upstream end opening toward the rear of the vehicle body, and fuel flowing toward a downstream end of the intake port 7a. A fuel injection valve 7b for injecting is provided. Further, an intake flow rate control device 21 that controls an intake flow rate supplied to the engine 5 is connected to an upstream end of the intake port 7a.
[0018]
As shown in FIG. 3, the intake flow control device 21 includes an idle valve having a throttle valve 31 having a main intake passage 32a communicating with the intake port 7a and an auxiliary intake passage 42a bypassing the throttle valve 31. And a valve 41.
[0019]
As shown in FIGS. 2 and 3, the throttle valve 31 includes a cylindrical throttle body 32 having a main intake passage 32a formed therein, and a throttle valve 32 provided inside the throttle body 32 to form a main intake passage 32a. A throttle valve 33 that opens and closes and a driving force transmission mechanism (not shown) that transmits driving force to the throttle valve 33 are provided. An air cleaner 23 is connected to an upstream end of the throttle body 32 via an intake duct 22. The downstream end of the throttle body 32 is connected to the cylinder head 7 via a connecting tube 24. A bypass inlet 32b communicating with the main intake passage 32a upstream of the throttle valve 33 and a bypass outlet 32c communicating with the main intake passage 32a downstream of the throttle valve 33 are provided on the side wall of the throttle body 32. Are formed.
[0020]
The idle valve 41 is provided with a casing 46 integrally fixed to the throttle body 32 and a casing 46 formed inside the casing 46. The idle valve 41 communicates between the bypass inlet 32b and the bypass outlet 32c outside the throttle body 32 to thereby control the throttle valve 33. A bypass valve (auxiliary intake flow rate control valve) 43 for controlling an auxiliary intake flow rate flowing through the auxiliary intake flow path 42; a step motor 44 for driving the bypass valve 43; A power transmission unit 45 for converting the rotational driving force of the step motor 44 into an advance / retreat driving force of the bypass valve 43; and an electronic control unit (not shown; hereinafter, ECU) for controlling the step motor 44. ing.
[0021]
The casing 46 has an auxiliary intake inlet 46a communicating with the bypass inlet 32b, an auxiliary intake outlet 46b communicating with the bypass outlet 32c, a communication between the auxiliary intake inlet 46a and the auxiliary intake outlet 46b, and a bypass valve 43 inserted therein. A valve hole 46c is formed.
[0022]
The bypass valve 43 has a substantially hollow cylindrical shape, and has a first valve hole 43a formed at a tip thereof, a second valve hole 43b formed in a side wall and communicating with the first valve hole 43a, and a third valve. And a hole 43c. When the bypass valve 43 moves back and forth in the valve hole 46c, the cross-sectional area of the communication flow path formed when the second valve hole 43b and the third valve hole 43c overlap the auxiliary intake outlet 46b is reduced. The auxiliary intake flow rate is controlled according to the size. Therefore, it is possible to control the flow rate of the auxiliary intake air to the engine 5 according to the position of the bypass valve 43 in the valve hole 46c.
[0023]
That is, as shown in the lower left diagram of FIG. 4, when the engine 5 is started, in order to maximize the intake flow rate to the engine 5, the total opening area of the second valve hole 43b and the third valve hole 43c is reduced. The opening area of the auxiliary intake outlet 46b is overlapped. As a result, as shown in the upper graph of this figure, the opening of the idle valve 41 (IACV opening) can be maximized to increase the engine speed (ENG speed).
In the warm-up operation after the start, as shown in the lower center diagram of FIG. 4, the third valve hole 43c and a part of the second valve hole 43b are communicated with the auxiliary intake outlet 46b. As a result, as shown in the upper graph in the figure, the opening of the idle valve 41 (IACV opening) can be adjusted to the valve opening during the warm-up operation.
Further, in the idling after the warm-up operation, as shown in the lower right diagram of FIG. 4, the second valve hole 43b is completely closed, and only the third valve hole 43c communicates with the auxiliary intake outlet 46b. As a result, as shown in the upper graph in this figure, the opening of the idle valve 41 (IACV opening) can be adjusted to the valve opening during idling.
[0024]
As shown in FIG. 3, the step motor 44 is fixed in the casing 41 so as to be coaxial with the valve hole 46c, and a male screw 44a1 is formed on the rotating shaft 44a. Reference numeral 47 denotes a seal member that prevents the intake air in the auxiliary intake passage 42 from leaking from the inside of the valve hole 46c to the outside.
The power transmission unit 45 includes a driving member 45a having a female screw hole 45a1 screwed to the rotating shaft 44a, and a spring 45b for fixing the bypass valve 43 to the driving member 45a. An Oldham joint 45c is interposed between the drive member 45a and the bypass valve 43, and can be relatively displaced in a radial direction about these axes. The spring 45b is an urging member that urges the bypass valve 43 against a flange 45a2 formed on the driving member 45a, and fixes the bypass valve 43 to the driving member 45a without rattling. ing.
[0025]
The ECU controls the number of steps of the step motor 44, and includes an atmospheric pressure table for obtaining an atmospheric pressure correction coefficient and a water temperature table for determining an auxiliary intake flow rate based on the temperature of cooling water for cooling the engine 5. (See FIG. 5 (a). It is set for each operation mode during starting and running.) And reference characteristics between the valve opening of the bypass valve 43 and the auxiliary intake air flow rate (that is, the step motor 44 is used as a reference). The reference mass flow rate table (see the bold line in FIG. 5B) that defines the step position and the mass flow rate when adjusted to the position, and the “IACV opening” on the horizontal axis indicates the valve opening. .), And a volume flow rate table indicating the step position of the step motor 44 required for obtaining a certain volume flow rate.
The ECU can read the atmospheric pressure value measured by an atmospheric pressure sensor (not shown) and the temperature of the cooling water.
[0026]
The control flow of the above-described intake flow control device 21 (hereinafter, IACV) will be described below with reference to FIGS. FIG. 6 shows an outline of the control flow, and FIGS. 7 and 8 show subroutines accompanying the control flow shown in FIG. In the following description, the idle speed is INE, and the target engine speed is target NE. Also, among the idling rotational speeds, the idling rotational speed to be obtained from now on is set to the current INE, the idling rotational speed obtained one step earlier in time from the present time is set to the previous INE, the actual idling rotational speed obtained by actual measurement is set to the current NE, A description will be given assuming that the idle speed measured one step before in time is NE last time.
[0027]
(1) Flow of step S1
When the ignition is turned on and the control of the IACV is started, first, in step S1, an atmospheric pressure correction coefficient is obtained. That is, as shown in the subroutine of FIG. 7A, in step S1-1, the atmospheric pressure table corresponding to the atmospheric pressure value measured by the atmospheric pressure sensor is referred to by referring to the atmospheric pressure table recorded in the ECU. Calculate the atmospheric pressure correction coefficient. After the atmospheric pressure correction coefficient is obtained in this manner, when starting or running, the process proceeds to step S2 in FIG. If the vehicle is idling, the process proceeds to step S3 in FIG.
[0028]
(2) Flow of step S2
When the process proceeds to step S2, the mass flow rate of intake air at the time of starting or running is obtained. That is, as shown in FIG. 7 (b), in the case of starting, the process proceeds to step S2-1, and among the water temperature tables of the ECU, the water temperature sensor for starting is measured by referring to the water temperature table for starting. The starting mass flow rate corresponding to the set water temperature is calculated. On the other hand, if the vehicle is running, the process proceeds to step S2-2, and among the water temperature tables of the ECU, the running water flow rate corresponding to the water temperature measured by the water temperature sensor is referred to by referring to the running water temperature table. Is calculated. After the mass flow rate of the intake air at the time of starting or traveling is obtained in this way, step S3 in FIG. 6 is skipped and the process proceeds to step S4.
[0029]
(3) Step S3 flow
When the process proceeds to step S3, a mass flow rate required for idling is obtained. That is, as shown in FIG. 7C, in step S3-1, an error is calculated as the absolute value of the difference between the measured current NE and the target NE. In the following step S3-2, the difference △ NE is calculated as the absolute value of the difference between the current NE and the previous NE. In a succeeding step S3-3, a PID mass flow rate is calculated based on the error and the difference ΔNE obtained in steps S3-1 and S3-2. In the subsequent step S3-4, the INE mass flow rate corresponding to the current INE is calculated by adding the PID mass flow rate calculated in step S3-3 to the mass flow rate corresponding to the previous INE. After the current INE mass flow rate is determined in this way, the process proceeds to step S4 in FIG.
[0030]
(4) Flow of step S4
In this step S4, a step position of the motor corresponding to the mass flow rate at the time of starting or running determined in step S2 or the idling mass flow rate (INE mass flow rate) determined in step S3 is determined. That is, as shown in FIG. 8A, first, in step S4-1, it is determined whether or not the engine is at the start. If it is at the time of starting, the process proceeds to step S4-2, and the starting mass flow rate is calculated by correcting the starting mass flow rate using the atmospheric pressure correction coefficient obtained at step S1-1. I do. In the following step S4-3, the target step position corresponding to the starting volume flow rate obtained in step S4-2 is calculated with reference to the volume flow rate table recorded in the ECU. After the target step position is obtained in this way, step S5 in FIG. 6 is skipped and the process proceeds to step S6.
[0031]
On the other hand, when it is determined in step S4-1 that it is not the time of starting, it is determined in step S4-4 whether the vehicle is running. When it is determined that the vehicle is traveling, the process proceeds to step S4-5, and when it is determined that the vehicle is idling, the process proceeds to step S4-7.
If the process proceeds to step S4-5, the running mass flow rate is calculated by correcting the running mass flow rate with the atmospheric pressure correction coefficient obtained in step S1-1. In the following step S4-6, the target step position corresponding to the running volume flow rate obtained in step S4-5 is calculated with reference to the volume flow rate table recorded in the ECU. After the target step position is obtained in this way, step S5 in FIG. 6 is skipped and the process proceeds to step S6.
[0032]
On the other hand, if it is determined in step S4-4 that the vehicle is not running, it is determined that the vehicle is idling and the process proceeds to step S4-7. The idle mass flow rate (INE volume flow rate) is calculated by correcting the idle mass flow rate (INE mass flow rate) with the atmospheric pressure using the atmospheric pressure correction coefficient obtained in step S1-1. In the following step S4-8, the target step position corresponding to the idle volume flow rate obtained in step S4-7 is calculated by referring to the volume flow rate table recorded in the ECU. After the target step position is obtained in this way, the process proceeds to step S5 in FIG.
[0033]
(5) Step S5 flow
In step S5, the reference position of the step motor 44 is replaced when the following first replacement condition and second replacement condition are both satisfied. That is, when the current idling rotational speed approaches the target idling rotational speed, the reference position of the step motor 44 is read (the ECU which is a means for determining whether or not the vehicle is idling at present is idling. When the determination is made, the reference position of the step motor 44 is replaced.
More specifically, as shown in FIG. 8B, first, in step S5-1, the error (the target idling rotational speed and the current idling rotational speed detected by the pulse sensor) obtained in step S3-1 are determined. If the absolute value of the difference is determined to be smaller than the predetermined threshold value (first threshold value), the process proceeds to step S5-2, assuming that the first reading condition is satisfied. If the first rewriting condition is not satisfied, the process proceeds to step S6 in FIG. 6 without rewriting.
[0034]
When the process proceeds to step S5-2, the reference volume flow rate is calculated by correcting the reference mass flow rate table in the ECU with the atmospheric pressure using the atmospheric pressure correction coefficient obtained in step S1-1. In the following step S5-3, the target step position a corresponding to the reference volume flow rate obtained in step S5-2 is calculated with reference to the volume flow table in the ECU. In the following step S5-3a, a target step position b corresponding to the INE volume flow is calculated from the volume flow table.
In a succeeding step S5-4, an absolute value of a difference between the target step position a obtained in the step S5-3 and the target step position b obtained in the step S5-3a is calculated, and this is calculated as a predetermined threshold value (the second threshold). If it is determined to be larger than (threshold), the process proceeds to step S5-5, and if it is determined to be smaller, the process proceeds to step S6 in FIG. That is, in step S5-4, the auxiliary intake air flow rate for obtaining the target idling rotational speed is calculated based on the calculated intake air flow rate and the reference based on the reference mass flow rate table (reference characteristic). When the absolute value of the difference from the intake flow rate becomes larger than the second threshold value, the process proceeds to step S6 assuming that the second reading condition is satisfied.
[0035]
When the process proceeds to step S5-5, the target step position obtained in step S5-3a is replaced with the target step position obtained in step S5-3.
That is, the target step position b (the valve opening corresponding to the calculated intake flow rate) obtained by the calculation is changed to the reference step position a (the valve opening corresponding to the reference intake flow rate on the reference characteristic) obtained based on the reference mass flow rate table. Degree). More specifically, as shown in FIG. 5B, when the IACV opening shifts in parallel with the valve characteristic shown by the broken line due to aging or the like from the valve characteristic at the time of factory shipment shown by the solid line, the same air Instead of the IACV opening (step position) for obtaining the flow rate obtained by calculation, an IACV opening obtained from valve characteristics at the time of factory shipment is adopted. For example, in the example shown in the figure, the IACV opening obtained by the calculation is ST2, but this is replaced with ST1 and read. As a result, even if a deviation occurs in the valve characteristics, it is possible to correct the deviation by software. After the target step position is read in this way, the process proceeds to step S6 in FIG.
[0036]
(6) Step S6 flow
In step S6, the step motor 44 is driven to a step position corresponding to the obtained target step position. That is, as shown in FIG. 8C, in step S6-1, the target step position obtained in any of the above steps S4-3, S4-6, and S4-8, or read in step S5-5. The target valve opening is obtained by rotating the step motor 44 with reference to the target step value thus obtained (that is, a target auxiliary intake flow rate is secured).
[0037]
As described above, the intake flow rate control device 21 of the present embodiment determines that the current idling speed is close to the target idling speed, and furthermore, the bypass valve 43 is displaced to require the reference position adjustment. If it is determined that there is a valve opening corresponding to the calculated intake flow rate, the valve opening corresponding to the reference intake flow rate is read as a correct valve opening degree rather than the valve opening degree for the calculated intake flow rate.
According to this configuration, since the reference position adjustment is not performed when the engine 5 is stopped, a drive circuit for backing up the operating power supply when the engine 5 is stopped is not required, and a timer for preventing the battery from running down is not required. Circuits and the like become unnecessary. Thereby, it is possible to prevent the circuit configuration from becoming complicated and increasing the cost. In addition, since it is not necessary to forcibly close or fully open the bypass valve 43 at the time of the reference position alignment, it is possible to prevent poor starting or sudden vehicle behavior.
Therefore, it is possible to achieve both prevention of cost increase and prevention of adverse effects on the starting characteristics.
[0038]
【The invention's effect】
The intake air flow control device for an internal combustion engine according to claim 1 of the present invention, when performing the reference position adjustment of the auxiliary intake air flow control valve, the absolute value of the difference between the target idle speed and the current idle speed. , The first read condition that becomes smaller than the first threshold value and the second read condition that the absolute value of the difference between the calculated intake flow rate and the reference intake flow rate becomes larger than the second threshold value are compatible. In such a case, a configuration is employed in which a reading step using a valve opening corresponding to a reference intake flow rate on the reference characteristic instead of the valve opening corresponding to the calculated intake air amount is performed.
According to this configuration, since the reference position adjustment is not performed when the internal combustion engine is stopped, a drive circuit for backing up the operating power supply when the internal combustion engine is stopped is not required, and a timer circuit or the like for preventing the battery from running down is also required. It becomes unnecessary. Thereby, it is possible to prevent the circuit configuration from becoming complicated and increasing the cost. In addition, it is not necessary to forcibly fully close or fully open the auxiliary intake flow rate control valve at the time of the reference position alignment, so that poor starting can be prevented.
As described above, according to the present invention, it is possible to achieve both prevention of cost increase and prevention of adverse effects on the starting characteristics.
[0039]
According to the intake valve control device for an internal combustion engine according to the second or third aspect of the present invention, it is possible to obtain the same effect as the intake valve control device for an internal combustion engine according to the first aspect.
[Brief description of the drawings]
FIG. 1 is a side view showing an embodiment of a motorcycle provided with an intake air flow control device for an internal combustion engine of the present invention.
FIG. 2 is a diagram showing a main part of the motorcycle, and is an enlarged sectional view of a part A in FIG. 1;
FIG. 3 is an explanatory diagram showing a schematic configuration of an intake air flow control device of the motorcycle.
FIG. 4 is an explanatory diagram illustrating the operation of the intake flow control device.
FIG. 5 is a diagram showing a table stored in an ECU of the intake air flow control device, wherein (a) is a water temperature table showing an air flow for obtaining a predetermined engine speed at a certain water temperature; b) is a reference mass flow rate table showing the correlation between the opening degree of the bypass valve and the auxiliary intake flow rate flowing at that time. The solid line is shifted from the factory to the valve characteristics, and the broken line is shifted in parallel to the factory shipping. This shows the valve characteristics at the time.
FIG. 6 is an explanatory diagram showing a control flow of the intake air flow control device.
7 is a diagram showing a part of a control flow of the intake air flow control device in detail, and (a) to (c) show respective subroutines of steps S1 to S3 in FIG.
FIG. 8 is a diagram showing a part of a control flow of the intake air flow control device, and (a) to (c) show respective subroutines of steps S4 to S6 in FIG.
[Explanation of symbols]
32a: Main intake passage
33 ・ ・ ・ Throttle valve
42 ... Auxiliary intake passage
43 ・ ・ ・ Bypass valve (auxiliary intake flow rate control valve)
44 ・ ・ ・ Step motor

Claims (3)

An auxiliary intake flow path that bypasses a throttle valve provided in the main intake flow path; an auxiliary intake flow rate control valve that is driven by a step motor to control an auxiliary intake flow rate that flows through the auxiliary intake flow path; In the intake flow rate control device which stores in advance the reference characteristics between the valve opening degree of the control valve and the auxiliary intake flow rate,
When idling,
A first read condition in which an absolute value of a difference between the target idling rotational speed and the current idling rotational speed is smaller than a first threshold value;
The absolute value of the difference between the calculated intake flow rate when the auxiliary intake flow rate for obtaining the target idling speed is obtained by calculation and the reference intake flow rate when calculated based on the reference characteristics is the second. And a second replacement condition that is larger than the threshold value of
When the first read condition and the second read condition are compatible, the valve opening corresponding to the reference intake flow rate is used along the reference characteristic instead of the valve opening corresponding to the calculated intake flow rate. An intake air flow control device for an internal combustion engine, which performs a reading process. In an intake valve control apparatus for an internal combustion engine, an auxiliary intake flow path that bypasses a throttle valve is provided in an intake system of the internal combustion engine, and an auxiliary intake flow rate control valve that is connected to a step motor and opens and closes the auxiliary intake flow path. ,
An intake valve control device for an internal combustion engine, wherein the reference position of the step motor is read when the current idling speed approaches a target idling speed. In an intake valve control apparatus for an internal combustion engine, an auxiliary intake flow path that bypasses a throttle valve is provided in an intake system of the internal combustion engine, and an auxiliary intake flow rate control valve that is connected to a step motor and opens and closes the auxiliary intake flow path. ,
An intake valve control system for an internal combustion engine, comprising: means for determining whether or not the engine is currently idling, and means for rewriting the reference position of the step motor when it is determined that the engine is idle. apparatus.

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