JP4103821B2 - Intake control device for internal combustion engine - Google Patents

Description

  The present invention relates to an intake control device for an internal combustion engine that adjusts an intake air amount by using a variable valve mechanism that can continuously change the lift characteristics of an intake valve and a throttle that opens and closes an intake passage.

In the field of internal combustion engines suitably used for vehicles, a technique for adjusting the intake air amount using a variable valve mechanism capable of continuously changing the valve lift amount and the operating angle of the intake valve is known. Patent Document 1 discloses a technique for correcting a lift characteristic based on an intake air amount detected by an air flow meter or the like so as to eliminate a shift in the lift characteristic of a variable valve mechanism due to a deposit or the like accumulated on an intake valve. ing. Patent Document 2 calculates an air-fuel ratio at the time of acceleration operation based on the oxygen concentration in the exhaust gas detected by the oxygen sensor, learns the estimated deposit amount based on this result, and learns this value. A technique for correcting the lift characteristics of a variable valve mechanism based on the above is disclosed.
JP 2003-148177 A JP-A-9-303165

  When such a variable valve mechanism and a throttle valve that opens and closes the intake passage are used together to control the lift characteristics and the throttle opening according to the required intake air amount, there are the following problems. Comparing the required intake air amount with the detected value of the intake air amount detected by the air flow meter, and trying to correct the lift characteristics and throttle opening based on the deviation (variation / error), the above deviation is If it is not possible to determine whether the cause is due to the variable valve mechanism side or the throttle side, accurate correction cannot be performed. As a cause on the variable valve mechanism side, for example, there is a change in valve clearance due to deposits accumulated around the intake valve. As a cause on the throttle side, for example, clogging of the throttle can be cited.

  FIG. 4 is a characteristic diagram showing the influence of the intake air amount due to errors and variations in the lift characteristics (valve lift amount and operating angle) of the intake valve. A characteristic F2 indicates a characteristic when the lift characteristic is smaller than the reference characteristic F1 due to deposits or the like adhering to the intake valve. As shown in the figure, the influence of the intake air amount due to the variation in lift characteristics tends to be more prominent as the lift characteristics become smaller. The reason for this is that in the operating range Rs with a small lift characteristic in which the lift amount is, for example, about 1 mm, the front and rear of the intake valve are in a so-called choked state, and the intake air amount is caused by a slight error in the effective opening area of the intake valve. This is because of a relatively large fluctuation. In other words, in the operating range Rl where the lift characteristics are relatively large, fluctuations in the intake air amount due to errors and variations in the lift characteristics are so small that they can be substantially ignored. That is, there is a standard state in which fluctuations in the intake air amount due to errors and variations in lift characteristics can be substantially ignored.

  On the other hand, with respect to the throttle opening, the influence of the throttle opening error and variation due to the throttle valve clogging etc. on the intake air amount tends to appear relatively uniformly regardless of the throttle opening. As in the case of the lift characteristic, there is no standard state in which the fluctuation of the intake air amount can be substantially ignored.

  The present invention has been made paying attention to such characteristics, and corrects both the lift characteristics and the throttle opening of the variable valve mechanism based on the detected value of the intake air amount. is there.

  An intake control apparatus for an internal combustion engine according to the present invention has intake detection means for detecting an intake air amount, and can continuously change a lift characteristic including at least one of a valve lift amount and an operating angle of an intake valve. The intake air amount is adjusted by using a variable valve mechanism and a throttle valve that opens and closes the intake passage. Under a predetermined correction operation region, first, a constant lift operation is performed to maintain the lift characteristic at a predetermined large lift, and under this constant lift operation, the throttle is based on the intake air amount detected by the intake air detection means. Correct the opening. Subsequently, reflecting this correction, a constant throttle operation is performed to maintain the throttle opening at a predetermined large opening, and the above-described intake air amount detected by the intake air detection means is based on the intake air amount under the constant throttle operation. Correct the lift characteristics.

First, based on the detected value of the intake air amount under a constant lift operation in which the lift characteristic of the intake valve is maintained at a predetermined large lift and fluctuations in the intake air amount due to errors and variations in the lift characteristic can be substantially ignored. It can be accurately corrected throttle opening Te, and a constant throttle operation to maintain the throttle opening to reflect this correction to a predetermined large opening can be accurately performed, under this constant throttle operation, suction The lift characteristic is corrected based on the detected value of the air amount. Thus, both the throttle opening degree and the lift characteristic can be accurately corrected based on the detected value of the intake air amount.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a system configuration diagram showing an intake control device for an internal combustion engine according to the present invention. An internal combustion engine 1 composed of a spark ignition gasoline engine has an intake valve 3 and an exhaust valve 4, and a variable valve mechanism 2 described later is provided as a valve mechanism on the intake valve 3 side. The valve operating mechanism on the exhaust valve 4 side is a direct acting type that drives the exhaust valve 4 by the exhaust camshaft 5, and its valve lift characteristic is always constant.

  The outlet side of the exhaust manifold 6 that collects the exhaust of each cylinder is connected to the catalytic converter 7. An air-fuel ratio sensor 8 for detecting the air-fuel ratio is provided upstream of the catalytic converter 7. A second catalytic converter 10 and a silencer 11 are provided on the downstream side of the catalytic converter 7. The air-fuel ratio sensor 8 may be an oxygen sensor that detects only the rich or lean air-fuel ratio, or may be a wide-area air-fuel ratio sensor that can provide an output corresponding to the value of the air-fuel ratio.

  A fuel injection valve 12 is disposed so as to inject and supply fuel to each cylinder toward the intake port of each cylinder. A branch passage 15 is connected to each intake port. The upstream ends of the plurality of branch passages 15 are connected to the collector 16. An intake inlet passage 17 is connected to one end of the collector 16. The intake inlet passage 17 is provided with an electronically controlled throttle valve 18 that opens and closes the intake passage. The electronically controlled throttle valve 18 includes an actuator 18a made of an electric motor, and its opening degree is controlled by a control signal supplied from an engine control unit 19. For example, a sensor 18b for detecting the actual opening of the throttle valve 18 is integrally provided, and the throttle valve opening is closed-loop controlled to the target opening based on the detection signal. An air flow meter 20 that detects the intake air flow rate is disposed upstream of the throttle valve 18, and an air cleaner 21 is further disposed upstream.

  In order to detect the engine speed and the crank angle position, a crank angle sensor 22 is provided for the crankshaft, and a vibration sensor 25 for detecting engine vibration is attached to the side wall of the cylinder block. Further, an accelerator opening sensor 23 for detecting an accelerator pedal opening (depression amount) operated by the driver is provided. These detection signals are input to the engine control unit 19 together with detection signals from the air flow meter 20, the air-fuel ratio sensor 8, and the like. In the engine control unit 19, based on these detection signals, the injection amount and injection timing of the fuel injection valve 12, the ignition timing by the ignition plug 24, the valve lift characteristics by the variable valve mechanism 2, the opening of the throttle valve 18, etc. To control.

  The variable valve mechanism 2 on the intake valve 3 side is known, for example, from Japanese Patent Application Laid-Open No. 2002-89341, and the valve lift amount and operation of the intake valves 3 of a plurality of cylinders are shown in FIG. A variable lift / operating angle mechanism 51 that continuously and variably controls both angles, and a phase variable mechanism that continuously advances or retards the central phase (phase relative to the crankshaft) of the operating angles of the intake valves of a plurality of cylinders. 52. In this way, according to the variable valve mechanism 2 that combines the lift / operating angle variable mechanism 51 and the phase variable mechanism 52, both the intake valve opening timing (IVO) and the intake valve closing timing (IVC) are independently set. It can be arbitrarily controlled, and in the low load range, by reducing the lift amount (maximum lift amount), it is possible to limit the intake air amount according to the load. In the region where the lift amount is large to some extent, the air amount flowing into the cylinder is mainly determined by the opening / closing timing of the intake valve 3, whereas in the state where the lift amount is sufficiently small, the air amount is mainly determined by the lift amount. .

  The variable lift / operating angle mechanism 51 includes a hollow drive shaft 53 that rotates in conjunction with the crankshaft, a drive eccentric cam portion 55 that is eccentrically provided on the drive shaft 53, and an obliquely upper side of the drive shaft 53. A control shaft 56 disposed in parallel, a control eccentric cam portion 57 provided eccentric to the control shaft 56, a rocker arm 58 swingably attached to the control eccentric cam portion 57, and the upper end of each intake valve 3 And a swing cam 60 that opens and closes the intake valve in contact with the tappet (or valve lifter) 59.

  The drive shaft 53 and the control shaft 56 are rotatably supported on the cylinder head side using a bearing bracket or the like. The drive eccentric cam portion 55 and the rocker arm 58 are linked by a first link 61. The first link 61 has an annular portion 61 a rotatably fitted on the outer peripheral surface of the drive eccentric cam portion 55, and an extension portion 61 b linked to one end portion of the rocker arm 58. The rocker arm 58 and the swing cam 60 are linked by a second link 62. The circular outer peripheral surface of the control eccentric cam portion 57 into which the rocker arm 58 is rotatably fitted is eccentric with respect to the axis of the control shaft 56. Therefore, the rocking center of the rocker arm 58 changes according to the angular position of the control shaft 56.

  The swing cam 60 is fitted to the outer periphery of the drive shaft 53 and is rotatably supported, and the lower end of the second link 62 is linked to the end extending sideways. On the lower surface of the swing cam 60, a base circle surface concentric with the drive shaft 53 and a cam surface extending in a predetermined curve from the base circle surface to the end are continuously provided. Is formed. The base circle surface is a section where the lift amount becomes zero, and when the swing cam 60 swings and the cam surface contacts the tappet 59, the lift is gradually lifted.

  The rotational position of the control shaft 56 is controlled by a lift / operating angle control actuator 65 formed of, for example, an electric motor provided at one end. Since the initial position of the control eccentric cam portion 57 can be continuously changed, the valve lift characteristic continuously changes accordingly. That is, the valve lift amount and the operating angle can be expanded and reduced simultaneously and continuously.

  Next, as shown in FIG. 2, the phase variable mechanism 52 relatively connects the sprocket 71 provided at the front end portion of the drive shaft 53 and the sprocket 71 and the drive shaft 53 within a predetermined angle range. And a hydraulic actuator 72 for phase control that is rotated to the right. The sprocket 71 is linked to the crankshaft via a timing chain or timing belt (not shown). Therefore, by the hydraulic pressure control to the phase control hydraulic actuator 72, the sprocket 71 and the drive shaft 53 are relatively rotated, and the lift center angle is retarded. That is, the lift characteristic curve itself does not change, and the whole advances or retards.

  As the control of the lift / working angle variable mechanism 51 and the phase variable mechanism 52, a sensor for detecting an actual lift / working angle or phase may be provided to perform closed-loop control, or simply according to operating conditions. You may make it open-loop control.

  In the above configuration, the opening degree of the electric control throttle valve 18 and the lift characteristic of the variable valve mechanism 2 are controlled so that the required intake air amount corresponding to the required torque determined by the accelerator pedal opening degree is obtained. The Typically, the opening degree of the electronically controlled throttle valve 18 is controlled so that a minimum negative pressure necessary for exhaust gas recirculation or the like is generated in the collector 16, and the suction negative pressure close to the atmospheric pressure is reduced. Thus, the variable valve mechanism 2 is controlled so that the amount of air flowing into the cylinder becomes optimum. In particular, in a low load range including idle, the throttle opening is relatively large by limiting the intake air amount by controlling the lift amount of the intake valve 3 to a minimum value of about 1 mm by the variable lift / operating angle mechanism 51. Thus, the throttle loss can be greatly reduced.

  As described above, the intake air amount can be adjusted and controlled by both the lift characteristic and the throttle opening. However, there is a possibility that the lift characteristics may have errors and variations over time due to deposits accumulated on the intake valves, deviations in valve clearance, and the like. Further, the throttle opening may cause an error or variation over time due to a throttle valve clogging or the like. Therefore, in order to accurately control the intake air amount, it is necessary to accurately correct both the lift characteristics and the throttle opening.

  FIG. 3 is a flowchart showing a flow of control for correcting the lift characteristic and the throttle opening according to the first embodiment of the present invention. First, in step 1, it is determined whether or not a predetermined correction operation region in which the lift characteristics and the throttle opening should be corrected. Here, as the correction operating range, the amount of intake air is small, so errors are likely to appear, and even if the in-cylinder pressure changes because the vehicle is stopped, there is little impact on the passengers. The later idle operating range is used.

  In step 2, a constant lift operation is started to maintain a lift characteristic at a predetermined large lift set in advance. That is, in this constant lift operation, the throttle opening is limited and controlled according to the required intake air amount in the idle operation region while fixing the lift characteristic to a large lift. Accordingly, the throttle opening in the constant lift operation is a minimum value near or close to the fully closed state. The above-mentioned large lift is a value that is much larger than the lift characteristics used in the normal idle operation range, for example, as described later in the constant throttle operation, and is within the range Rl shown in FIG. This corresponds to a range in which the variation in the intake air amount due to the variation is substantially negligible. For example, the operating angle used in a high load region is a value of 180 ° CA or more.

  In step 3, the throttle opening correction process is executed under this constant lift operation. Specifically, the required intake air amount is compared with the detected value of the intake air amount detected by the air flow meter 20, and a correction value for the reference position of the throttle opening is calculated based on the deviation between the two. . This correction value is stored and updated in the backup memory, and is reflected in the subsequent throttle control.

  In step 4, in the idling operation range after warming up, and immediately after completion of the correction of the throttle opening in step 3, the throttle opening correction value is reflected by reflecting the correction value of the throttle opening obtained in step 3. A constant throttle operation is performed to maintain a predetermined large opening. That is, in this constant throttle operation, the lift characteristic is limited to a small amount according to the required intake air amount while fixing the throttle opening to a large opening. Therefore, the lift characteristic in this constant throttle operation is a minimum value with a lift amount of about 1 mm. The large opening is a value that is much larger than, for example, the opening near the fully closed position used in the above-described constant lift operation, and is, for example, a value that is fully open or near the fully opened position.

  In step 5, the learning / correction processing of the lift characteristics is executed under this constant throttle operation. Specifically, the required intake air amount is compared with the detected value of the intake air amount detected by the air flow meter 20, and a correction value for the reference position of the lift characteristic is calculated based on the deviation between the two. This correction value is reflected in the subsequent control of the lift characteristic.

  As described above with reference to FIG. 4, in the operating range Rl where the lift characteristic is relatively large, fluctuations in the intake air amount due to errors and variations in the lift characteristic become so small that they can be substantially ignored. On the other hand, with regard to the throttle opening, fluctuations in the intake air amount due to errors and variations in the throttle opening due to clogging of the throttle valve, etc. tend to appear relatively uniformly regardless of the throttle opening. As in the case of characteristics, there is no region where the influence of errors and variations can be substantially ignored.

  Therefore, contrary to the present embodiment, when the lift characteristic is corrected under a constant lift operation after the lift characteristic is corrected under a constant throttle operation, the former lift characteristic is not accurately corrected. The latter correction of the throttle opening, which reflects this correction, is also inaccurate.

  According to the present embodiment, first, a constant lift operation is performed in which the lift characteristic is maintained at a predetermined large lift that can substantially ignore fluctuations in the intake air amount due to the error, and under this constant lift operation, the intake air is maintained. The throttle opening can be accurately corrected based on the detected value of the amount, and a constant throttle operation in which the throttle opening is a predetermined large opening can be accurately performed by reflecting this correction. Then, under such a constant throttle operation, the lift characteristics can be accurately corrected based on the detected value of the intake air amount. That is, it is possible to accurately correct both the throttle opening degree and the lift characteristic based on the detected value of the intake air amount.

  Further, according to the present embodiment, since the throttle opening correction and the lift characteristic correction are continuously performed in the idling operation region which is the same operation condition, there is no occurrence of error / variation due to environmental changes.

  When shifting from constant lift operation to constant throttle operation, it is necessary to greatly reduce the lift characteristics and greatly increase the throttle opening, although the intake air amount may fluctuate transiently, In the idling operation region after warming up, the influence of the transitional intake air amount as described above on the drivability is less than when the vehicle is running.

  Preferably, at the time of lift correction in step 5, a variation in the lift characteristic of the intake valve between the cylinders is detected, and when this variation is large, the minimum set value of the lift characteristic is corrected to the increase side. Thereby, the dispersion | variation in the lift characteristic between cylinders can also be eliminated favorably.

  More preferably, the lower limit value of the lift characteristic for performing the lean operation is corrected to the increase side in accordance with the correction amount to the increase side of the minimum set value. Thereby, when using the control to ensure the robustness by performing lean operation with the lift characteristic as the minimum set value, by increasing the lower limit value of the lift characteristic according to the correction amount to the increase side of the minimum set value, The lower limit of the lift characteristic for executing the lean operation is raised, and even if deterioration due to long-time operation occurs, it is possible to avoid a decrease in drivability.

  As described above, the present invention has been described based on the specific embodiments. However, the present invention is not limited to the above-described embodiments, and includes various modifications and changes without departing from the spirit of the present invention. . For example, the variable valve mechanism is not limited to the combination of the lift / operating angle variable mechanism 51 and the phase variable mechanism 52 as in the above embodiment, and at least one of the valve lift amount and the operating angle of the intake valve is not limited. The present invention can be similarly applied to a variable valve mechanism that can continuously change the lift characteristics including it.

  The technical ideas of the present invention that can be understood from the above description are listed together with the effects thereof.

(1) Variable valve mechanism 2 (lift / operating angle variable mechanism 51) capable of continuously changing the lift characteristics including at least one of the valve lift amount (maximum lift amount) and the operating angle of intake valve 3, and intake passage An intake control device for an internal combustion engine that adjusts the intake air amount in combination with a throttle valve 18 that opens and closes,
Intake air detection means (air flow meter 20) for detecting the intake air amount;
A constant lift operation means for performing a constant lift operation for maintaining the lift characteristics at a predetermined large lift under a predetermined correction operation region (step 2);
Throttle correction means for correcting the throttle opening based on the intake air amount detected by the intake detection means under the constant lift operation (step 3);
A constant throttle operation means for performing a constant throttle operation to maintain the throttle opening at a predetermined large opening reflecting the correction by the throttle correction means under the correction operation range (step 4);
Lift correcting means for correcting the lift characteristics based on the intake air amount detected by the intake detecting means under the constant throttle operation (step 5);
Have

(2) More specifically, the throttle opening is reduced according to the required intake air amount in the idle operation region while maintaining the lift characteristics at a predetermined large lift under the idle operation region after warming up. Constant lift operation means for performing a constant lift operation (step 2);
Throttle correction means for correcting the throttle opening based on the comparison between the required intake air amount and the intake air amount detected by the intake detection means under the constant lift operation (step 3);
In accordance with the required intake air amount while maintaining the throttle opening at a predetermined large opening, reflecting the correction by the throttle correction means after the constant lift operation in the idling operation area after warming up. Constant throttle operation means for performing constant throttle operation to reduce the lift characteristic (step 4);
Under this constant throttle operation, there is a lift correcting means (step 5) for correcting the lift characteristics based on a comparison between the required intake air amount and the intake air amount detected by the intake detecting means.

  According to the inventions of (1) or (2), first, the throttle is determined based on the detected value of the intake air amount under a constant lift operation in which the influence on the intake air amount due to the lift characteristic error can be substantially ignored. It is possible to accurately correct the opening, and to reflect this correction, it is possible to accurately perform a constant throttle operation in which the throttle opening is a predetermined large opening. Under this constant throttle operation, the intake air The lift characteristic can be accurately corrected based on the detected value of the amount. That is, it is possible to accurately correct both the throttle opening degree and the lift characteristic based on the detected value of the intake air amount. In addition, since a sensor or the like that directly detects the throttle opening degree and the lift characteristic is not required for the correction, the number of parts and the cost are not increased.

  (3) Typically, the large lift is at least a value larger than the lift characteristic in the constant throttle operation, and the large opening is at least a value larger than the throttle opening in the constant lift operation.

  (4) Preferably, the variable valve mechanism (lift / operating angle variable mechanism 51) includes a control shaft 56, a control eccentric cam portion 57 provided eccentric to the control shaft 56, and the control eccentric cam portion 57. A rocker arm 58 that is swingably attached to the drive shaft 53, a drive shaft 53 that rotates in conjunction with the crankshaft, a valve cam 60 that is swingably attached to the drive shaft 53 and opens and closes the intake valve, and A drive eccentric cam portion 55 provided eccentric to the drive shaft 53, a first link 61 that links the drive eccentric cam portion 55 and one end of the rocker arm 58, the other end of the rocker arm 58, and a valve cam And a second link 62 that links 60.

  In such a mechanism 51, the drive shaft 53 and the valve cam 60 can be arranged at substantially the same positions as the cam shaft and fixed cam of a general direct acting valve system. It can be easily applied to a valve-type internal combustion engine without significantly changing the layout, and it is compact and has excellent engine mountability. In addition, since many of the connecting portions of the link elements, such as the connecting portion of the drive eccentric cam portion 55 and the first link 61, are in surface contact with a slide bearing or the like, lubrication is easy, and durability and reliability are also improved. Are better.

  (5) Preferably, the lift correction means detects variations in lift characteristics of the intake valves between the cylinders, and corrects the minimum setting value of the lift characteristics to the increase side when the variations are large. Thereby, the dispersion | variation in the lift characteristic between cylinders can also be eliminated favorably.

  (6) More preferably, the lower limit value of the lift characteristic for performing the lean operation is corrected to the increase side in accordance with the correction amount to the increase side of the minimum set value. Thereby, when using the control to ensure the robustness by performing lean operation with the lift characteristic as the minimum set value, by increasing the lower limit value of the lift characteristic according to the correction amount to the increase side of the minimum set value, The lower limit of the lift characteristic for executing the lean operation is raised, and even if deterioration due to long-time operation occurs, it is possible to avoid a decrease in drivability.

1 is a system configuration diagram showing an intake control device for an internal combustion engine according to an embodiment of the present invention. The perspective view which shows the principal part of a variable valve mechanism. The flowchart which shows the flow of correction control of a lift characteristic and throttle opening. The characteristic view which shows the influence on the amount of intake air by the error of a lift characteristic.

Explanation of symbols

2 ... Variable valve mechanism 3 ... Intake valve 18 ... Throttle valve 20 ... Air flow meter (intake amount detection means)
51. Lift / operating angle variable mechanism

Claims (7)

An internal combustion engine that adjusts an intake air amount by using a variable valve mechanism that can continuously change a lift characteristic including at least one of a valve lift amount and an operating angle of an intake valve and a throttle valve that opens and closes an intake passage Intake control device of
Intake detection means for detecting the amount of intake air;
A constant lift operation means for performing a constant lift operation for maintaining the lift characteristics at a predetermined large lift in which fluctuations in the intake air amount due to errors and variations in the lift characteristics are substantially negligible under a predetermined correction operation range;
Under this constant lift operation, throttle correction means for correcting the throttle opening based on the intake air amount detected by the intake detection means,
A constant throttle operation means for performing a constant throttle operation for maintaining the throttle opening at a predetermined large opening reflecting the correction by the throttle correction means under the correction operation range;
Lift correction means for correcting the lift characteristics based on the intake air amount detected by the intake air detection means under the constant throttle operation;
An intake control device for an internal combustion engine. An internal combustion engine that adjusts an intake air amount by using a variable valve mechanism that can continuously change a lift characteristic including at least one of a valve lift amount and an operating angle of an intake valve and a throttle valve that opens and closes an intake passage Intake control device of
Intake detection means for detecting the amount of intake air;
Under the idle operation range after warming up, the above-mentioned lift characteristics are maintained at a predetermined large lift that can substantially ignore the fluctuations in the intake air amount due to errors and variations in the lift characteristics, and the required intake in this idle operation area A constant lift operation means for performing a constant lift operation to reduce the throttle opening according to the amount of air;
Under this constant lift operation, throttle correction means for correcting the throttle opening based on a comparison between the required intake air amount and the intake air amount detected by the intake detection means;
In accordance with the required intake air amount while maintaining the throttle opening at a predetermined large opening, reflecting the correction by the throttle correction means after the constant lift operation in the idling operation area after warming up. Constant throttle operation means for performing constant throttle operation to reduce lift characteristics;
Under this constant throttle operation, based on a comparison between the required intake air amount and the intake air amount detected by the intake detection means, lift correction means for correcting the lift characteristics;
An intake control device for an internal combustion engine.   The intake control device for an internal combustion engine according to claim 1 or 2, wherein the large lift is at least larger than a lift characteristic in the constant throttle operation, and the large opening is at least larger than a throttle opening in the constant lift operation. The variable valve mechanism is
A control axis;
A control eccentric cam provided eccentric to the control shaft;
A rocker arm swingably attached to the control eccentric cam portion;
A drive shaft that rotates in conjunction with the crankshaft;
A valve operating cam that swingably attaches to the drive shaft and opens and closes the intake valve;
A drive eccentric cam portion provided eccentric to the drive shaft;
A first link that links the drive eccentric cam portion and one end of the rocker arm;
A second link linking the other end of the rocker arm and the valve cam;
The intake control device for an internal combustion engine according to any one of claims 1 to 3.   The lift correction means detects a variation in lift characteristics of the intake valves between the cylinders, and corrects the minimum set value of the lift characteristics to the increase side when the variation is large. Intake control device for internal combustion engine.   6. The intake control apparatus for an internal combustion engine according to claim 5, wherein the lower limit value of the lift characteristic for performing lean operation is corrected to the increase side according to the correction amount to the increase side of the minimum set value. A variable valve mechanism having intake detection means for detecting the intake air amount and capable of continuously changing a lift characteristic including at least one of a valve lift amount and an operating angle of the intake valve, and a throttle for opening and closing the intake passage An intake control method for an internal combustion engine that adjusts the intake air amount by using a valve together,
Under a predetermined correction operation area, a constant lift operation is performed to maintain the lift characteristic at a predetermined large lift in which fluctuations in the intake air amount due to errors and variations in the lift characteristic can be substantially ignored ,
Under this constant lift operation, the throttle opening is corrected based on the intake air amount detected by the intake detection means,
Reflecting this correction, a constant throttle operation is performed to maintain the throttle opening at a predetermined large opening,
An intake control method for an internal combustion engine, wherein the lift characteristic is corrected based on an intake air amount detected by the intake detection means under the constant throttle operation.

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