JP2010037967A - Controller of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller for an internal combustion engine capable of reducing variation in the suction air amount by stabilizing at early stage the pressure in the suction passage when the suction valve is started operating, and of establishing a high precision in the air-fuel ratio control. <P>SOLUTION: The controller of the internal combustion engine is equipped with valve stopping mechanisms 27 and 28 capable of stopping the suction valve 21 and an exhaust valve 22 at the closing positions of a suction port 19 and an exhaust port 20 respectively, a suction chamber capacity changing mechanism which consists of an auxiliary port 32, communication valves 36 and 37, and a communication valve opening/closing mechanism 38 and changes the capacity of the suction chamber 61 between a throttle valve 33 and the suction valve 21, and an ECU 51 which changes smaller the capacity of the suction chamber 61 by closing the communication valves 36 and 37 when the suction valve 21 and the exhaust valve 22 are stopped by the valve stopping mechanisms 27 and 28, and when the suction and exhaust valves 21 and 22 are put in operation by the mechanisms 27 and 28 respectively, changes larger the capacity of the suction chamber 61 by opening the communication valves 36 and 37 after elapse of a certain period of time since the valves 21 and 22 were started operating. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine having a valve closing mechanism capable of stopping an intake valve capable of opening and closing an intake port at a closed position.

  In a general internal combustion engine, an intake valve and an exhaust valve are urged and supported at positions where the intake port and the exhaust port are closed by an urging force of a spring. The intake port and exhaust port can be opened at the timing. By the way, there has been proposed one in which the operation of all or some of the cylinders is stopped depending on the operation state of the internal combustion engine. For example, during fuel cut control of an internal combustion engine, the intake valve and the exhaust valve are stopped at a position where the intake port and the exhaust port are closed by the valve closing mechanism, thereby improving the fuel consumption and the air (oxygen) to the catalyst. The supply is stopped to prevent deterioration of the catalyst.

  As a control device for an internal combustion engine having such a valve closing mechanism, for example, there is one described in Patent Document 1 below. In the control apparatus for an internal combustion engine described in Patent Document 1, the opening degree of the throttle valve is set to a first threshold value and a second threshold value set to a higher load side than the first threshold value. When the stop operation is continued for a predetermined time, and the stop operation is continued for a predetermined time, and when this stop operation is switched to the all cylinder operation, the upper limit of the throttle valve opening is set for this predetermined time. A value is set to prevent the throttle valve from opening more than necessary.

JP 2006-283720 A

  In the control device for an internal combustion engine having the conventional valve closing mechanism described above, as described above, the intake valve and the exhaust valve are stopped at the position where the intake port and the exhaust port are closed by the valve closing mechanism during the fuel cut control. The catalyst is prevented from deteriorating by stopping the supply of air (oxygen) to the catalyst. However, at the time of fuel cut control, the throttle valve is closed and the intake valve and the exhaust valve are closed. Therefore, the pressure in the intake passage from the throttle valve to the intake valve is almost atmospheric pressure. When the valve closing mechanism is stopped from this state and the operation of the intake valve and the exhaust valve is started, the atmospheric pressure air in the intake passage is introduced into the combustion chamber through the intake port. Therefore, until the air in the intake passage is consumed, that is, until the pressure in the intake passage is stabilized from the atmospheric pressure to a predetermined negative pressure state, the amount of air taken into the combustion chamber varies, and the air-fuel ratio control is increased. It becomes difficult to carry out with accuracy.

  The present invention is for solving such a problem, and by stabilizing the pressure of the intake passage when starting the operation of the intake valve at an early stage, the variation in the intake air amount is reduced to reduce the air-fuel ratio. An object of the present invention is to provide a control device for an internal combustion engine that enables high-precision control.

  In order to solve the above-described problems and achieve the object, a control device for an internal combustion engine according to the present invention is provided with a combustion chamber, an intake passage communicating with the combustion chamber, and between the combustion chamber and the intake passage. An intake valve, a valve closing mechanism capable of stopping the intake valve at a closed position, an intake control valve provided in the intake passage, and a volume of the intake chamber between the intake control valve and the intake valve in the intake passage Control device for an internal combustion engine, comprising: an intake chamber volume changing mechanism capable of changing the intake valve; and an intake control means capable of controlling the intake valve control valve and the intake chamber volume changing mechanism in accordance with an operating state of the internal combustion engine The intake control means closes the intake control valve when the intake valve is stopped by the valve rest mechanism and changes the volume of the intake chamber to be small by the intake chamber volume change mechanism. Stop by valve mechanism When operating the intake valve, the volume of the intake chamber is largely changed by the intake chamber volume changing mechanism after a predetermined period of time has elapsed since the start of the operation of the intake valve. .

  In the control device for an internal combustion engine of the present invention, the intake control means stops the intake valve by the valve closing mechanism and closes the intake control valve at the time of fuel cut control, and closes the intake control valve by the intake chamber volume changing mechanism. It is characterized by changing the volume of the intake chamber to be small.

  In the control device for an internal combustion engine according to the present invention, the predetermined period is a period from when the intake valve starts operating by the valve closing mechanism until the pressure in the intake chamber is stabilized in a steady state. Yes.

  In the control apparatus for an internal combustion engine of the present invention, the predetermined period is a period until the rate of change of the pressure in the intake chamber becomes smaller than a preset threshold value.

  In the control apparatus for an internal combustion engine according to the present invention, the predetermined period is a period until the rate of change of the air amount in the intake chamber becomes smaller than a preset threshold value.

  According to the control device for an internal combustion engine of the present invention, a valve closing mechanism capable of stopping the intake valve at the closed position, and an intake chamber volume capable of changing the volume of the intake chamber between the intake control valve and the intake valve in the intake passage. The intake control means closes the intake control valve when the intake valve is stopped by the valve closing mechanism, and changes the volume of the intake chamber to be small by the intake chamber volume changing mechanism. When the stopped intake valve is operated, the volume of the intake chamber is largely changed by the intake chamber volume changing mechanism after a predetermined period has elapsed since the start of the operation of the intake valve. Therefore, when the operation of the intake valve is started, the pressure of the intake chamber is stabilized at an early stage by greatly changing the volume of the intake chamber after a lapse of a predetermined period from the start of the operation of the intake valve, and the air taken into the combustion chamber The variation in the amount can be reduced, and the air-fuel ratio control can be made highly accurate.

  Embodiments of an internal combustion engine control apparatus according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this Example.

  FIG. 1 is a schematic configuration diagram illustrating an internal combustion engine control apparatus according to an embodiment of the present invention, FIG. 2 is a flowchart illustrating air-fuel ratio control by the internal combustion engine control apparatus of the present embodiment, and FIG. It is a time chart showing the air-fuel ratio control by the control apparatus of the example internal combustion engine.

  In the internal combustion engine of this embodiment, as shown in FIG. 1, a cylinder head 12 is fastened on a cylinder block 11, and pistons 14 are respectively movable up and down in a plurality of cylinder bores 13 formed in the cylinder block 11. It is mated. A crankcase 15 is fastened to the lower part of the cylinder block 11, and a crankshaft 16 is rotatably supported in the crankcase 15. Each piston 14 is connected to the crankshaft 16 via a connecting rod 17. Has been.

  The combustion chamber 18 is constituted by the wall surface of the cylinder bore 13 in the cylinder block 11, the lower surface of the cylinder head 12, and the top surface of the piston 14, and the combustion chamber 18 has a high central portion at the upper portion (lower surface of the cylinder head 12). It has a pent roof shape that is slanted. An intake port 19 and an exhaust port 20 are formed on the upper portion of the combustion chamber 18, that is, the lower surface of the cylinder head 12, and the intake valve 19 and the exhaust valve 20 are opposed to the intake port 19 and the exhaust port 20. The lower end portions of 22 are respectively positioned. The intake valve 21 and the exhaust valve 22 are supported by the cylinder head 12 so as to be movable in the axial direction, and the intake port 19 and the exhaust port 20 are closed by a valve spring (not shown) (upward in FIG. 1). Is supported by urging. An intake camshaft 23 and an exhaust camshaft 24 are rotatably supported on the cylinder head 12, and the intake cam 25 and the exhaust cam 26 are in contact with upper ends of the intake valve 21 and the exhaust valve 22.

  Although not shown, the crankshaft sprocket fixed to the crankshaft 16 and the camshaft sprockets respectively fixed to the intake camshaft 23 and the exhaust camshaft 24 are wound with endless timing chains. The crankshaft 16, the intake camshaft 23, and the exhaust camshaft 24 can be interlocked.

  Accordingly, when the intake camshaft 23 and the exhaust camshaft 24 rotate in synchronization with the crankshaft 16, the intake cam 25 and the exhaust cam 26 move up and down the intake valve 21 and the exhaust valve 22 at a predetermined timing. 19 and the exhaust port 20 can be opened and closed so that the intake port 19 and the combustion chamber 18 can communicate with the combustion chamber 18 and the exhaust port 20, respectively. In this case, the intake camshaft 23 and the exhaust camshaft 24 are set to rotate once (360 degrees) while the crankshaft 16 rotates twice (720 degrees). Therefore, the engine performs four strokes of the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke while the crankshaft 16 rotates twice. At this time, the intake camshaft 23 and the exhaust camshaft 24 rotate once. Will be.

  In addition, the valve mechanism of the engine includes valve stop mechanisms 27 and 28 that stop the intake valve 21 and the exhaust valve 22 at positions where the intake port 19 and the exhaust port 20 are closed according to the operating state. The valve stop mechanisms 27 and 28 are, for example, locks (not shown) that allow the intake cam 25 to be engaged and disengaged with respect to the intake cam shaft 23 and the exhaust cam 26 to be disengaged from the exhaust cam shaft 24 Mechanism. Therefore, when the intake cam 25 is detached from the intake camshaft 23 and the exhaust cam 26 is detached from the exhaust camshaft 24 by this lock mechanism, the intake valve 21 and the exhaust valve 22 close the intake port 19 and the exhaust port 20. You can stop at the position you want.

  An intake pipe 30 is connected to the intake port 19 via an intake manifold 29, and an air cleaner 31 is attached to an air intake port of the intake pipe 30. The intake pipe 30 is provided with an auxiliary port 32 having a U-shape. An electronic throttle device 34 having a throttle valve 33 is provided downstream of the air cleaner 31 and upstream of the auxiliary port 32. A communication valve opening / closing device 38 having communication valves 36, 37 that are linked by a support shaft 35 is provided at each communication portion of the auxiliary port 32 with the intake pipe 30. In this embodiment, the auxiliary port 32, the communication valves 36 and 37, and the communication valve opening / closing device 38 constitute the intake chamber volume changing mechanism of the present invention.

  An exhaust pipe 40 is connected to the exhaust port 20 via an exhaust manifold 39, and the exhaust pipe 40 has a three-way catalyst 41 and a NOx occlusion reduction type catalyst 42 for purifying harmful substances contained in the exhaust gas. Is installed. The three-way catalyst 41 simultaneously purifies HC, CO, and NOx contained in the exhaust gas by an oxidation-reduction reaction when the air-fuel ratio (exhaust air-fuel ratio) is stoichiometric. The NOx occlusion reduction type catalyst 42 is in a rich combustion region or a stoichiometric combustion region where the NOx contained in the exhaust gas is temporarily stored when the air-fuel ratio (exhaust air-fuel ratio) is lean, and the oxygen concentration in the exhaust gas is reduced. Sometimes, the stored NOx is released and NOx is reduced by the added fuel as a reducing agent.

  An exhaust gas recirculation passage (EGR passage) 43 is provided between the downstream side of the auxiliary port 32 in the intake pipe 30 and the upstream side of the three-way catalyst 41 in the exhaust pipe 40. Are provided with an EGR valve 44 and an EGR cooler 44. Further, an EGR gas temperature sensor 46 for detecting the temperature of the EGR gas is provided on the EGR passage 43 closer to the intake pipe 30 than the EGR valve 44.

  An injector (fuel injection valve) 47 that injects fuel into the intake port 19 is attached to the cylinder head 12, and this injector 47 is attached to the cylinder head 12. The injectors 47 attached to the respective cylinders are connected to a delivery pipe (not shown), and a fuel supply system is connected to the delivery pipe via a fuel supply pipe. In addition, the cylinder head 12 is provided with a spark plug 48 that is positioned above the combustion chamber 18, specifically, on the uppermost wall portion of the ceiling of the combustion chamber 18 to ignite the air-fuel mixture.

  The vehicle is equipped with an electronic control unit (ECU) 51, which can control the fuel injection timing of the injector 47, the ignition timing of the spark plug 48, and the like. The fuel injection amount, injection timing, ignition timing, and the like are determined based on engine operating conditions such as temperature, throttle opening, accelerator opening, intake pipe pressure, engine speed, and coolant temperature.

  That is, an airflow sensor 52 and an intake air temperature sensor 53 are mounted on the upstream side of the intake pipe 30, and the measured intake air amount and intake air temperature are output to the ECU 51. The electronic throttle device 34 is provided with a throttle position sensor 54, and the accelerator pedal is provided with an accelerator position sensor 55, which outputs the current throttle opening and accelerator opening to the ECU 51. Further, a pressure sensor 56 is attached corresponding to the auxiliary port 32 in the intake pipe 30, and the measured intake pipe pressure is output to the ECU 51. The crankshaft 16 is provided with a crank angle sensor 57 and outputs the detected crank angle to the ECU 51. The ECU 51 discriminates an intake stroke, a compression stroke, an expansion stroke, an exhaust stroke in each cylinder based on the crank angle, and an engine. Calculate the number of revolutions. The cylinder block 11 is provided with a water temperature sensor 58 and outputs the detected engine cooling water temperature to the ECU 51.

  An air-fuel ratio (A / F) sensor (or oxygen sensor) 59 is provided upstream of the three-way catalyst 41 in the exhaust pipe 40. The A / F sensor 59 detects the exhaust air / fuel ratio (oxygen amount) of the exhaust gas exhausted from the combustion chamber 18 to the exhaust pipe 40 through the exhaust port 20 and the exhaust manifold 39, and outputs the detected exhaust air / fuel ratio to the ECU 51. is doing. The ECU 51 corrects the fuel injection amount by feeding back the exhaust air-fuel ratio detected by the A / F sensor 59 and comparing it with the target air-fuel ratio set according to the engine operating state.

  Further, the ECU 51 can control the valve stop mechanisms 27 and 28 based on the engine operating state. For example, the ECU 51 executes fuel cut control for stopping fuel injection from the injector 47 when the driver is using the engine brake, thereby suppressing wasteful fuel consumption and improving fuel efficiency. . At this time, the supply of air (oxygen) to the three-way catalyst 41 is stopped by stopping the intake valve 21 and the exhaust valve 22 at positions where the intake port 19 and the exhaust port 20 are closed by the valve stop mechanisms 27 and 28. The deterioration of the three-way catalyst 41 is prevented.

  However, during this fuel cut control, the throttle valve 33 is closed and the intake valve 21 is closed by the valve stop mechanisms 27 and 28, so the pressure in the intake chamber from the throttle valve 33 to the intake valve 21 is almost atmospheric pressure. When the valve stop mechanisms 27 and 28 are stopped from this state and the operation of the intake valve 21 is started, atmospheric pressure air in the intake chamber is introduced into the combustion chamber 18 through the intake port 19. Therefore, until the air in the intake chamber is consumed, that is, until the pressure in the intake chamber is stabilized from the atmospheric pressure to a predetermined negative pressure state, the amount of air sucked into the combustion chamber 18 varies, and the air-fuel ratio control is performed. It becomes difficult to carry out with high accuracy.

  Therefore, in the control device for the internal combustion engine of the present embodiment, the intake chamber volume changing mechanism (auxiliary port 32, communication valve 36, etc.) that can change the volume of the intake chamber 61 between the throttle valve 33 and the intake valve 21 in the intake passage. 37, the communication valve opening / closing device 38) is provided, and the ECU 51 as the intake control means closes the throttle valve 33 and stops the communication valve by the communication valve opening / closing device 38 when the intake valve 21 is stopped by the valve stop mechanisms 27, 28. When the intake valve 21 stopped by the valve stop mechanisms 27 and 28 is operated while the volumes 36 and 37 are closed to reduce the volume of the intake chamber 61, the predetermined period of time set in advance from the start of the operation of the intake valve 21 is used. After the passage, the communication valves 36 and 37 are opened by the communication valve opening / closing device 38 to greatly change the volume of the intake chamber 61.

  Specifically, during fuel cut control, the ECU 51 stops the intake valve 21 by the valve stop mechanisms 27 and 28, closes the throttle valve 33, and closes the communication valves 36 and 37 by the communication valve opening / closing device 38. The volume of the intake chamber 61 is changed to be small.

  In this case, the predetermined period is a period from when the intake valve 21 starts operating by the valve stop mechanisms 27 and 28 until the pressure in the intake chamber 61 is stabilized in a steady state. Specifically, the predetermined period is a period until the pressure change rate of the intake chamber 61 becomes smaller than a preset threshold value. Further, the predetermined period is a period until the rate of change of the air amount in the intake chamber 61 becomes smaller than a preset threshold value.

  Hereinafter, the air-fuel ratio control by the control device for the internal combustion engine of the present embodiment will be described based on the flowchart of FIG.

  In the air-fuel ratio control by the control device for the internal combustion engine of this embodiment, as shown in FIG. 2, stop / operation switching control of the intake valve 21 and the exhaust valve 22 by the valve stop mechanisms 27 and 28 is performed in step S11. . In step S <b> 12, the ECU 51 determines whether or not there is a request for “large” intake capacity by the intake chamber volume changing mechanism due to fuel consumption and emission according to the engine operating state. If it is determined that there is no request for “large” intake capacity by the intake chamber volume changing mechanism, the communication valves 36 and 37 are closed by the communication valve opening / closing device 38 in step S16, and the intake pipe 30 and the auxiliary port 32 are closed. Is changed so that the capacity (volume) of the intake chamber 61 is reduced.

  On the other hand, if it is determined in step S12 that there is a request for “large” intake capacity by the intake chamber volume changing mechanism, the ECU 51 determines in step S13 whether the intake valve 21 and the exhaust valve 22 are operating. To do. Here, the ECU 51 determines that the intake valve 21 and the exhaust valve 22 are not operating when the intake valve 21 and the exhaust valve 22 are stopped by the valve stop mechanisms 27 and 28 in order to perform the fuel cut control. In step S16, the communication valves 36 and 37 are closed by the communication valve opening / closing device 38, the intake pipe 30 and the auxiliary port 32 are shut off, and the capacity of the intake chamber 61 is changed.

  On the other hand, if it is determined in step S13 that the intake valve 21 and the exhaust valve 22 are operating, in step S14, the ECU 51 is set in advance after the intake valve 21 and the exhaust valve 22 start (return). It is determined whether the predetermined time has elapsed.

  Here, the predetermined period set in advance is that the pressure in the intake chamber 61 that has been atmospheric pressure after the intake valve 21 and the exhaust valve 22 stopped by the valve stop mechanisms 27 and 28 start operating again. This is a period until the steady state (predetermined negative pressure state) is stabilized, and is a period set in advance by experiments based on the volume of the intake chamber 61. Instead of the predetermined period set in advance, a period until the rate of change of the pressure in the intake chamber 61 (suction pipe pressure) detected by the pressure sensor 56 becomes smaller than a preset threshold or the air flow sensor 52 is set. It is good also as a period until the change rate of the air quantity of the intake chamber 61 detected by becomes smaller than the preset threshold value.

  If it is determined in step S14 that the predetermined time has not elapsed after the intake valve 21 and the exhaust valve 22 are started (returned), the communication valves 36 and 37 are turned on by the communication valve opening / closing device 38 in step S16. The intake pipe 30 and the auxiliary port 32 are shut off, and the capacity of the intake chamber 61 is kept small.

  On the other hand, if it is determined in step S14 that a predetermined time has elapsed after the intake valve 21 and the exhaust valve 22 are started (returned), the communication valves 36 and 37 are connected by the communication valve opening / closing device 38 in step S15. Is opened, the intake pipe 30 and the auxiliary port 32 are connected, and the capacity of the intake chamber 61 is changed.

  Here, the operation of the air-fuel ratio control by the above-described internal combustion engine control apparatus of the present embodiment will be described based on the time chart of FIG.

In the air-fuel ratio control by the control apparatus for an internal combustion engine of the present embodiment, as shown in FIG. 3, at time t _1, when the fuel cut control is performed, the intake valve 21 and the exhaust valve by the valve stop mechanism 27, 28 When 22 closes the intake port 19 and the exhaust port 20, the pressure in the intake chamber 61 (intake pipe pressure) increases to near atmospheric pressure, and the air amount in the intake chamber 61 decreases to near zero. At this time, conventionally, the capacity switching of the intake chamber 61 is not executed, but in this embodiment, the communication valves 36 and 37 are closed by the communication valve opening and closing device 38, the intake pipe 30 and the auxiliary port 32 are shut off, and the intake air The chamber 61 is switched so as to reduce the capacity.

Then, at time _{t 2,} when the fuel cut control is terminated, the intake valve 21 and the exhaust valve 22 by the valve stop mechanism 27 releases the operation (return) to the intake port 19 and exhaust port 20. At this time, since the capacity of the intake chamber 61 remains large in the past, the pressure of the intake chamber 61, which was atmospheric pressure, returns to the steady state (predetermined negative pressure state), and the intake air amount is stable. A predetermined period A (time t _{2 to} t ₅ ) is required until the air-fuel ratio (A / F) returns to the stoichiometric air-fuel ratio. On the other hand, in this embodiment, since the volume of the intake chamber 61 is switched to a small volume in advance, the pressure of the intake chamber 61, which was atmospheric pressure, returns to the steady state (predetermined negative pressure state), and the suction is performed. The time required until the air amount is stabilized, that is, until the air-fuel ratio (A / F) returns to the stoichiometric air-fuel ratio, is a predetermined time B (time t _{2 to} t ₃ ) shorter than the conventional predetermined period A. .

Thereafter, when the intake valve 21 and the exhaust valve 22 start to operate (time t ₂ ) and reach a time t ₄ that is a predetermined period C, the communication valves 36 and 37 are opened by the communication valve opening / closing device 38, and the intake pipe 30 The capacity of the intake chamber 61 is increased by communicating with the auxiliary port 32.

  As described above, in the control apparatus for the internal combustion engine of the present embodiment, the valve stop mechanisms 27 and 28 capable of stopping the intake valve 21 and the exhaust valve 22 at the closed positions of the intake port 19 and the exhaust port 20 are provided, and the throttle As an intake chamber volume changing mechanism capable of changing the volume of the intake chamber 61 between the valve 33 and the intake valve 21, an auxiliary port 32, communication valves 36 and 37, and a communication valve opening / closing mechanism 38 are provided. The ECU 51 is a valve stop mechanism. When the intake valve 21 and the exhaust valve 22 are stopped by the valves 27 and 28, the communication valves 36 and 37 are closed to reduce the volume of the intake chamber 61, while the intake valves 21 and 27 stopped by the valve stop mechanisms 27 and 28 and When the exhaust valve 22 is operated, the communication valves 36 and 37 are opened after a predetermined period from the start of the operation of the intake valve 21 and the exhaust valve 22 to greatly change the volume of the intake chamber 61.

  Accordingly, when the operation of the intake valve 21 and the exhaust valve 22 is started, the intake chamber 61 is changed so that the volume of the intake chamber 61 becomes larger after a predetermined period from the start of the operation of the intake valve 21 and the exhaust valve 22. Can be reduced and stabilized at an early stage, variation in the amount of air taken into the combustion chamber 18 can be reduced, and high-precision air-fuel ratio control can be achieved. Further, by shortening the lean operation period until the pressure in the intake chamber 61 is stabilized, it is possible to suppress the deterioration of the three-way catalyst 41 and to purify the exhaust gas at an early stage, thereby reducing the NOx emission amount. While being able to reduce, a misfire can be prevented and the response of an engine can be improved.

  In the control device for the internal combustion engine of the present embodiment, the ECU 51 stops the intake valve 21 and the exhaust valve 22 by the valve stop mechanisms 27 and 28, closes the throttle valve 33, and closes the communication valve 36 during fuel cut control. , 37 are closed, and the volume of the intake chamber 61 is changed to be small. Therefore, at the time of fuel cut control, by stopping the intake valve 21 and the exhaust valve 22 by the valve stop mechanisms 27, 28, it is possible to improve fuel efficiency and suppress deterioration of the three-way catalyst 41, When the throttle valve 33 is closed and the communication valves 36 and 37 are closed and the volume of the intake chamber 61 is changed to be small, the valve stop mechanisms 27 and 28 start the operation of the intake valve 21 and the exhaust valve 22. The amount of air in the intake chamber 61 can be reduced, and the pressure in the intake chamber 61 can be stabilized at an early stage.

  Further, in the control apparatus for an internal combustion engine of the present embodiment, after the intake valve 21 and the exhaust valve 22 are activated by the valve stop mechanisms 27 and 28 for a predetermined period, until the pressure in the intake chamber 61 is stabilized in a steady state. It's a period. Therefore, the pressure of the intake chamber 61 can be stabilized at an early stage by changing the volume of the intake chamber 61 after the pressure of the intake chamber 61 is stabilized.

  Specifically, the predetermined period is a period until the rate of change of the pressure in the intake chamber 61 becomes smaller than a preset threshold value, or the rate of change of the air amount in the intake chamber 61 is greater than a preset threshold value. The period until it becomes smaller. Therefore, by using the pressure sensor 56 and the air flow meter 52, the predetermined period can be easily set by an existing apparatus, and the cost can be reduced.

  As described above, the control device for an internal combustion engine according to the present invention greatly changes the volume of the intake chamber after a predetermined period has elapsed since the start of the operation of the intake valve when operating the stopped intake valve. By stabilizing the pressure in the intake passage at the start of the engine at an early stage, it is possible to reduce the variation in the intake air amount and to improve the accuracy of the air-fuel ratio control, which is useful for any internal combustion engine It is.

1 is a schematic configuration diagram illustrating a control device for an internal combustion engine according to an embodiment of the present invention. It is a flowchart showing the air fuel ratio control by the control apparatus of the internal combustion engine of a present Example. It is a time chart showing the air fuel ratio control by the control apparatus of the internal combustion engine of a present Example.

Explanation of symbols

18 Combustion Chamber 19 Intake Port 20 Exhaust Port 21 Intake Valve 22 Exhaust Valve 27, 28 Valve Stop Mechanism (Valve Close Mechanism)
30 Intake pipe 32 Auxiliary port (Intake chamber volume changing mechanism)
33 Throttle valve (intake control valve)
34 Electronic throttle device 36, 37 Communication valve (Intake chamber volume changing mechanism)
38 Communication valve switch (Intake chamber volume changing mechanism)
47 injector 48 spark plug 51 electronic control unit, ECU (intake control means)

Claims (5)

A combustion chamber;
An intake passage communicating with the combustion chamber;
An intake valve provided between the combustion chamber and the intake passage;
A valve closing mechanism capable of stopping the intake valve at a closed position;
An intake control valve provided in the intake passage;
An intake chamber volume changing mechanism capable of changing the volume of the intake chamber between the intake control valve and the intake valve in the intake passage;
In a control apparatus for an internal combustion engine comprising an intake control means capable of controlling the valve closing mechanism, the intake control valve, and the intake chamber volume changing mechanism according to an operating state of the internal combustion engine,
The intake control means closes the intake control valve when the intake valve is stopped by the valve closing mechanism, and changes the volume of the intake chamber to be small by the intake chamber volume changing mechanism. When the intake valve stopped by the operation is operated, the volume of the intake chamber is largely changed by the intake chamber volume changing mechanism after the elapse of a predetermined period from the start of the operation of the intake valve. Engine control device.   In the fuel cut control, the intake control means stops the intake valve by the valve closing mechanism, closes the intake control valve, and changes the volume of the intake chamber to be small by the intake chamber volume changing mechanism. The control device for an internal combustion engine according to claim 1, wherein   3. The internal combustion engine according to claim 1, wherein the predetermined period is a period from when the intake valve is started to operate by the valve closing mechanism to when the pressure in the intake chamber is stabilized in a steady state. Engine control device.   4. The control apparatus for an internal combustion engine according to claim 3, wherein the predetermined period is a period until the rate of change of the pressure in the intake chamber becomes smaller than a preset threshold value.   The control apparatus for an internal combustion engine according to claim 3, wherein the predetermined period is a period until the rate of change of the air amount in the intake chamber becomes smaller than a preset threshold value.

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