JP2010223126A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a possibility of the rise of oil by negative pressure by preventing the inside of a combustion chamber from being brought into negative pressure during deceleration in speed. <P>SOLUTION: An internal combustion engine 10 includes a variable valve train 38 capable of holding an intake valve 34 in a stop state for each cylinder 12. During the deceleration of the internal combustion engine, the intake valve 34 is held in a stop state, an exhaust valve 36 is held in normal open and close states, and fuel injection is stopped in each cylinder to be controlled which is a part of a plurality of cylinders. In the remaining cylinders to be controlled, normal combustion control is performed. Since the in-cylinder pressure of the cylinders to be controlled can be raised during the deceleration, the negative pressure generated in the cylinders to be controlled can be suppressed while an engine brake is sufficiently applied to reduce the rise of oil by the negative pressure. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly to a control device for an internal combustion engine capable of temporarily holding a valve in a closed state.

  As a conventional technique, for example, as disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-137969), a control device for an internal combustion engine provided with a variable valve mechanism is known. The variable valve mechanism of the prior art includes a valve stop mechanism that can hold the valve in a temporarily closed state (valve stop state). And in the prior art, when performing fuel cut at the time of deceleration, the intake valve and the exhaust valve are held in the valve stop state, and when the engine brake is required, the opening and closing operation of the exhaust valve is resumed. Yes.

JP 2004-137969 A

  In the above-described conventional technology, the engine brake is applied by restarting the opening and closing operations of the exhaust valve while holding the intake valve in the valve stop state. However, after the exhaust valve is closed (after the exhaust stroke is finished), the pressure in the combustion chamber is almost equal to the atmospheric pressure. When the intake stroke of the next cycle is started in this state, the combustion chamber is in a negative pressure state due to the lowering operation of the piston, and a phenomenon (so-called oil rise) in which oil on the crankcase side is sucked into the combustion chamber by this negative pressure. There is a problem that occurs.

  Here, for example, when both the intake valve and the exhaust valve are in the valve stop state, air enters the combustion chamber from the crankcase side, so the negative pressure in the combustion chamber gradually decreases and the oil rises. Decreases over time. However, when only the intake valve is stopped, the air entering the combustion chamber from the crankcase side is exhausted, so the negative pressure state in the combustion chamber is not sufficiently eliminated and the oil rise continues. Will occur.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to suppress a negative pressure state in the combustion chamber during deceleration or the like, and to reduce oil increase due to the negative pressure. An object of the present invention is to provide a control device for an internal combustion engine that can perform the above-described operation.

A first invention is provided in at least some cylinders of a plurality of cylinders of an internal combustion engine, and an intake variable valve mechanism capable of holding an intake valve of the cylinder in a valve stop state;
When the internal combustion engine is in a specific operation state including deceleration, the intake valve is held in the valve stop state and the exhaust valve is normally opened and closed only by the control target cylinder that is at least part of the plurality of cylinders. A partial cylinder stopping means for maintaining the state and stopping fuel injection of the cylinder;
Exhaust pressure increasing means for increasing the pressure of the exhaust passage of the internal combustion engine when the exhaust stroke of the cylinder to be controlled is performed;
It is characterized by providing.

  According to the second invention, the exhaust pressure increasing means is configured to be exhaust gas discharged from other cylinders excluding the control target cylinder.

  According to a third aspect of the present invention, the control target cylinder is selected from the plurality of cylinders such that an exhaust valve of the control target cylinder is closed during an exhaust stroke of the other cylinder.

According to a fourth aspect of the present invention, there is provided an exhaust variable valve mechanism that is provided in at least some of the plurality of cylinders and is capable of holding an exhaust valve of the cylinder in a valve stop state.
A reduced-cylinder operation means for performing a reduced-cylinder operation for stopping the intake valve, the exhaust valve, and fuel injection in a part of the cylinders including the control target cylinder,
The partial cylinder stopping means is configured to return the exhaust valve of the control target cylinder to a normal open / closed state when the internal combustion engine enters the specific operation state during the reduced cylinder operation.

  According to a fifth aspect of the invention, there is provided an exhaust valve advance means that advances at least the opening / closing timing of the exhaust valve of the control target cylinder more than usual when the intake valve of the control target cylinder is in a valve deactivation state. .

  According to a sixth aspect of the invention, the exhaust pressure increasing means includes an exhaust throttle valve provided in the exhaust passage so as to be openable and closable.

  In a seventh aspect of the present invention, a cylinder to be selected as the control target cylinder among the plurality of cylinders is changed every time the specific operation state appears, and target cylinder switching is performed so that normal combustion is performed in cylinders other than the control target cylinder. It is set as the structure provided with a means.

  According to the first invention, the partial cylinder stop means can hold the intake valve of the cylinder to be controlled in the valve stop state and open and close the exhaust valve when the internal combustion engine is in a deceleration state or the like. . In this state, the exhaust pressure increasing means can increase the exhaust pressure in the exhaust passage when the exhaust stroke of the control target cylinder is performed, and can increase the in-cylinder pressure of the control target cylinder. In addition, since the exhaust valve opens and closes in the cylinder to be controlled, pump loss can be generated and the engine brake can be applied. Therefore, the negative pressure generated in the cylinder of the cylinder to be controlled can be suppressed while the engine brake is sufficiently applied at the time of deceleration, and the oil increase due to the negative pressure can be reduced.

  According to the second aspect of the invention, the exhaust pressure can be increased by the exhaust gas discharged from the non-control target cylinder, and the in-cylinder pressure of the control target cylinder can be increased by the exhaust pressure.

  According to the third invention, the control target cylinder can be selected such that the exhaust valve of the control target cylinder is closed during the exhaust stroke of the non-control target cylinder. Therefore, when the exhaust pressure is increased by the exhaust gas of the non-control target cylinder, this exhaust pressure can be applied to the cylinder of the control target cylinder, and the cylinder pressure of the control target cylinder can be efficiently increased.

  According to the fourth invention, the partial cylinder stopping means can return the exhaust valve of the cylinder to be controlled to the normal open and closed states when the internal combustion engine is in a decelerating state or the like during the reduced cylinder operation. . As a result, in the cylinder to be controlled, the exhaust valve can be opened and closed while the intake valve and the fuel injection are held in the stopped state, as in the case of the deceleration state during normal operation. Therefore, the present invention can also be applied to a cylinder that performs a reduced-cylinder operation.

  According to the fifth aspect of the invention, the exhaust valve advance means can advance the opening / closing timing of the exhaust valve of the cylinder more than usual when the intake valve of the cylinder to be controlled is in the valve resting state. As a result, in the cylinder to be controlled, it is possible to introduce more exhaust gas into the combustion chamber at an earlier time as the opening timing of the exhaust valve becomes earlier. Therefore, the cylinder pressure of the cylinder to be controlled can be reliably increased and the oil rise can be suppressed.

  According to the sixth invention, when the exhaust valve of the cylinder to be controlled is closed, a part of the exhaust passage is closed by the exhaust throttle valve, and the exhaust pressure in the closed space can be further increased. As a result, the in-cylinder pressure of the cylinder to be controlled can be efficiently increased, and oil rise can be reliably suppressed.

  According to the seventh aspect, the target cylinder switching means can change the cylinder to be selected as the control target cylinder every time the internal combustion engine enters a deceleration state or the like. Accordingly, the cylinders to be controlled can be sequentially changed, so that the frequency and amount of oil increase can be equalized for each cylinder. Therefore, for example, it is possible to avoid oil concentration from occurring intensively in a specific cylinder, and deposits and the like caused by oil in the cylinder. That is, oil rise can be suppressed evenly in all cylinders.

It is a whole block diagram for demonstrating the system configuration | structure of Embodiment 1 of this invention. FIG. 3 is a cross-sectional view showing the variable intake valve mechanism provided in each cylinder of the internal combustion engine in a state where the intake variable valve mechanism is broken perpendicular to the camshaft. It is sectional drawing shown in the state which fractured | ruptured the intake variable valve mechanism along the axial direction of a cam shaft. It is explanatory drawing for demonstrating the intake valve stop control at the time of deceleration. In Embodiment 1 of this invention, it is a flowchart which shows the control performed by ECU. In Embodiment 2 of this invention, it is explanatory drawing for demonstrating the reduced cylinder driving | running | working before performing intake valve stop control. In Embodiment 2 of this invention, it is a flowchart which shows the control performed by ECU. In Embodiment 3 of this invention, it is explanatory drawing for demonstrating the intake valve stop control at the time of deceleration. In Embodiment 3 of this invention, it is a flowchart which shows the control performed by ECU. In Embodiment 4 of this invention, it is a flowchart which shows the control performed by ECU. In Embodiment 5 of this invention, it is a flowchart which shows the control performed by ECU.

Embodiment 1 FIG.
[Configuration of Embodiment 1]
The first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is an overall configuration diagram for explaining a system configuration according to the first embodiment of the present invention. The system of the present embodiment includes an internal combustion engine 10 mounted on a vehicle, and the internal combustion engine 10 is constituted by a multi-cylinder engine having, for example, four cylinders. FIG. 1 illustrates only one cylinder of the internal combustion engine 10. Each cylinder 12 of the internal combustion engine 10 is provided with a combustion chamber 16 that expands and contracts by reciprocating movement of the piston 14. The piston 14 is connected to the crankshaft 18.

  The internal combustion engine 10 also includes an intake passage 20 that sucks intake air into the cylinder 12 and an exhaust passage 22 that discharges exhaust gas from the cylinder 12. The intake passage 20 is provided with an air flow meter 24 for detecting the amount of intake air and an electronically controlled throttle valve 26. The throttle valve 26 is driven by a throttle motor 28 based on the accelerator opening and the like to increase or decrease the intake air amount. Further, in the cylinder 12 of the internal combustion engine, a fuel injection valve 30 for injecting fuel into the intake passage 20, an ignition plug 32 for igniting the air-fuel mixture in the combustion chamber 16, and the intake passage 20 are opened with respect to the combustion chamber 16. , An intake valve 34 for closing, and an exhaust valve 36 for opening and closing the exhaust passage 22 with respect to the combustion chamber 16 are provided. Note that two intake valves 34 and two exhaust valves 36 are arranged per cylinder.

  The internal combustion engine 10 also includes an intake variable valve mechanism 38, an exhaust variable valve mechanism 40, and a VVT 42. Here, the intake variable valve mechanism 38 has a function of temporarily stopping the opening / closing operation of the intake valve 34 (holding the valve in a valve stop state). 36 has a function of holding the valve in the valve stop state. The configuration of these variable valve mechanisms 38 and 40 will be described later. The VVT 42 is a known variable valve timing system as described in, for example, Japanese Patent Application Laid-Open No. 2003-293711, and is provided in the exhaust valve 36, for example. The VVT 42 advances and retards the phase (opening timing and closing timing) of the exhaust valve 36 in accordance with a control signal input from the ECU 50 described later.

  Furthermore, the system of the present embodiment includes a sensor system including a crank angle sensor 44, an accelerator sensor 46, a vehicle speed sensor 48, and the like, and an ECU (Electronic Control Unit) 50 that controls the operating state of the internal combustion engine 10. . The crank angle sensor 44 outputs a signal synchronized with the rotation of the crankshaft 18, and the ECU 50 detects the engine speed based on this output. The accelerator sensor 46 detects the driver's accelerator operation, and the vehicle speed sensor 48 is configured to detect the speed of the vehicle.

  In addition to the air flow meter 24 and the sensors 44 to 48 described above, the sensor system includes various sensors necessary for controlling the vehicle and the internal combustion engine (for example, a water temperature sensor for detecting a cooling water temperature of the internal combustion engine, an air-fuel ratio of the exhaust gas). Air-fuel ratio sensors to be detected and the like are included, and these are connected to the input side of the ECU 50. Various actuators including a throttle motor 28, a fuel injection valve 30, a spark plug 32, variable valve mechanisms 38 and 40, a VVT 42, and the like are connected to the output side of the ECU 50.

  Then, the ECU 50 drives each actuator while detecting the operation state of the internal combustion engine by the sensor system. Specifically, based on the output of the sensor system, the fuel injection amount and injection timing, the ignition timing, the operating states and phases of the valves 34 and 36, etc. are set, and the actuator is driven according to these setting contents. . The operation control by the ECU 50 includes intake valve stop control during deceleration, which will be described later.

  Next, the configuration of the variable valve mechanisms 38 and 40 will be described with reference to FIGS. Since these variable valve mechanisms have the same configuration, the intake variable valve mechanism 38 will be described as an example, and the description of the exhaust variable valve mechanism 40 will be omitted.

  FIG. 2 is a cross-sectional view showing a state in which the variable intake valve mechanism provided in each cylinder of the internal combustion engine is broken perpendicularly to the camshaft. FIG. 3 is a cross-sectional view showing the intake variable valve mechanism broken along the axial direction of the camshaft. As shown in these drawings, the intake variable valve mechanism 38 is disposed between the camshaft 60 and the intake valve 34 of the internal combustion engine. The camshaft 60 is provided with one main cam 62 made of an eccentric normal cam and two sub cams 64 made of a circular zero lift cam for each cylinder.

  The intake variable valve mechanism 38 includes one drive arm 66 and left and right driven arms 68L and 68R (in some cases, both are collectively referred to as a driven arm 68) disposed on both sides of the drive arm 66. These arms 66 and 68 are supported by a support shaft 70 so as to be swingable. The drive arm 66 is in contact with the main cam 62 via a roller, and is configured to swing under the action force of the main cam 62. The driven arm 68 is in contact with the auxiliary cam 64 via a roller and is in contact with the valve stem of the intake valve 34. In addition, the arms 66 and 68 are provided with a switching mechanism 72 for switching the connection state between them.

  The switching mechanism 72 includes sleeves 74, 76L, and 76R provided on the arms 66, 68R, and 68L, two switching pins 78 and 80, a return spring 82, and an actuator 84, respectively. Then, the center switching pin 78 is displaced to either the connection release position inserted only in the center sleeve 74 or the connection position inserted across the two sleeves 74 and 76L. Further, the right switching pin 80 is displaced to either a connection release position inserted only in the right sleeve 76R or a connection position inserted across the two sleeves 74 and 76R. On the other hand, the return spring 82 urges the switching pins 78 and 80 toward the connection release position. The actuator 84 is controlled by the ECU 50 and pushes the switching pins 78 and 80 toward the coupling position.

  According to the above configuration, when the actuator 84 is operated, the switching pins 78 and 80 pushed by the actuator 84 are displaced to the coupling position against the spring force of the return spring 82. As a result, the arms 66 and 68 are connected by the switching pins 78 and 80, and the acting force of the main cam 62 is transmitted from the drive arm 66 to the driven arm 68, so that the exhaust valve 34 is normally opened and closed. Further, when the actuator 84 is stopped, as shown in FIG. 3, the switching pins 78 and 80 are displaced to the connection release position by the spring force of the return spring 82 and the connection of the arms 66 and 68 is released. The driven arm 68 remains stationary even when the oscillates, and the exhaust valve 34 enters a valve stop state in which the opening and closing operations are stopped. Therefore, the ECU 50 can switch the intake valve 34 of each cylinder to the valve stop state at a desired timing by controlling the actuator 84 of each cylinder.

(Intake valve stop control during deceleration)
Next, the intake valve stop control during deceleration executed by the ECU 50 will be described. As a valve control performed when the internal combustion engine decelerates, a control method is known in which the exhaust valve 36 is opened and closed while the intake valve 34 is held in a valve stop state in order to sufficiently apply the engine brake. However, in this method, the pressure in the combustion chamber 16 becomes substantially equal to the atmospheric pressure after the exhaust stroke ends. When the intake stroke of the next cycle is started in this state, the inside of the combustion chamber 16 is brought into a negative pressure state by the lowering operation of the piston 14, and a phenomenon in which the oil on the crankcase side is sucked into the combustion chamber 16 by this negative pressure ( Oil rise) will occur. On the other hand, for example, if both the valves 34 and 36 are opened and closed during fuel cut during deceleration, deterioration of the exhaust catalyst may be promoted, and both the valves 34 and 36 are set to the valve stop state. In such a case, the engine brake may be insufficient.

  In order to solve these problems, the present embodiment is configured to execute intake valve stop control during deceleration. FIG. 4 is an explanatory diagram for explaining intake valve stop control during deceleration. As shown in this figure, in each cylinder 12 of the internal combustion engine 10, two intake valves 34 and two exhaust valves 36 are arranged per cylinder. Of these four valves 34, 36, the black circle (●) indicates the intake valve held in the valve stop state by the intake variable valve mechanism 38, and the white circle (◯) indicates the normal opening / closing operation. Shows the valve being performed.

  As shown in FIG. 4, in the intake valve stop control, when the internal combustion engine is decelerated, the intake valves 34 of specific control target cylinders (for example, # 1 cylinder and # 4 cylinder) are held in the valve stop state. To do. In the cylinder to be controlled, fuel injection and ignition are also stopped, but only the exhaust valve 36 is opened and closed as usual. Note that the cylinders to be controlled are some cylinders selected in advance from the four cylinders by a selection method described later. On the other hand, in cylinders other than the control target cylinder (for example, # 2 cylinder and # 3 cylinder), the opening and closing operations of the intake valve 34 and the exhaust valve 36, fuel injection and ignition are executed as usual, and the combustion chamber 16 The air-fuel mixture is burned inside.

  Further, when selecting the cylinder to be controlled, the ignition order (combustion cycle order and phase difference) of each cylinder is taken into consideration, for example, during the exhaust stroke of the non-control target cylinder (# 2, # 3 cylinder) The control target cylinder is determined so that the exhaust valves 36 of (# 1, # 4 cylinders) are closed. When the control target cylinder is selected in this way, when the pressure (exhaust pressure) of the exhaust passage 22 is increased by the exhaust gas discharged from the non-control target cylinder, this exhaust pressure is applied to the cylinder of the control target cylinder. Therefore, the in-cylinder pressure of the cylinder to be controlled can be increased efficiently. That is, the exhaust gas discharged from the non-control target cylinder constitutes an exhaust pressure increasing means for increasing the exhaust pressure when the exhaust stroke of the control target cylinder is performed.

  Therefore, according to the above configuration, the in-cylinder pressure of the cylinder to be controlled can be increased as compared with the case where the intake valve stop control is not executed. Moreover, in the cylinder to be controlled, the exhaust valve 36 opens and closes even when the intake valve 34 is in the valve stop state, so that a pump loss can be generated and the engine brake can be applied. As described above, in the present embodiment, the negative pressure generated in the cylinder of the cylinder to be controlled can be suppressed and the oil increase due to the negative pressure can be reduced while the engine brake is sufficiently applied during deceleration. . Therefore, it is possible to avoid wasteful consumption of the oil in the oil pan due to the oil rising.

  Further, in the intake valve stop control, the intake valve 34 of the control target cylinder is brought into a valve stop state during deceleration, so that air (oxygen) is not supplied from the control target cylinder to the exhaust catalyst. Moreover, the non-control target cylinder discharges the exhaust gas that has become substantially oxygen-free by combustion in the cylinder toward the exhaust catalyst. Therefore, at the time of deceleration, it is possible to prevent oxygen from being supplied to the high temperature exhaust catalyst and to suppress deterioration of the catalyst.

  Further, in the present embodiment, in the non-control target cylinder, the intake air amount is reduced as much as possible within a range where combustion is established, and the fuel injection amount is controlled according to the intake air amount. Specifically, the intake air amount of the non-control target cylinder is reduced by appropriately reducing the opening degree of the throttle valve 26 (throttle opening degree). Here, when the intake valve stop control is not executed, the intake air amount per cylinder becomes too small compared to the minimum injection amount of the fuel injection valve 30 when the throttle opening is reduced during deceleration. As a result, an amount of fuel corresponding to the amount of intake air cannot be accurately injected, and A / F deviation, misfire, and the like are likely to occur. On the other hand, if the throttle opening during deceleration is increased in consideration of avoiding misfire and the minimum injection amount of the injection valve, the effectiveness of the engine brake becomes worse and the drivability is reduced.

  On the other hand, in the present embodiment, even if the entire intake air amount is reduced by reducing the throttle opening at the time of deceleration, the amount of control target cylinders per cylinder of the non-control target cylinders is as much as the valve stop state. The amount of intake air can be increased. As a result, in each non-control target cylinder, accurate fuel injection can be performed according to the intake air amount, and A / F deviation, misfire, and the like can be prevented. In addition, considering the avoidance of misfire and the minimum injection amount of the injection valve, it is not necessary to increase the throttle opening at the time of deceleration, so that the engine braking force can be sufficiently ensured.

[Specific Processing for Realizing Embodiment 1]
FIG. 5 is a flowchart showing the control executed by the ECU in the first embodiment of the present invention. In the routine shown in FIG. 5, first, in steps 100 and 102, it is determined whether or not the vehicle has been decelerated. That is, in step 100, the vehicle speed is detected by the vehicle speed sensor 48, and it is determined whether or not the vehicle speed is equal to or higher than a predetermined value corresponding to the traveling. In step 102, the accelerator operation amount of the driver is detected by the accelerator sensor 46, and it is determined whether or not the accelerator operation amount is equal to or less than a predetermined value close to zero.

  When both the determinations in steps 100 and 102 are satisfied, it is determined that the vehicle is in a deceleration state, and the above-described intake valve stop control during deceleration is executed (step 104). On the other hand, when the determination is not established in any one of steps 100 and 102, since the vehicle is not in a deceleration state, normal operation is performed (step 106). Thus, when the deceleration state of the vehicle is detected, intake valve stop control can be performed.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIGS. The feature of this embodiment is that the present invention is applied to a system that performs reduced-cylinder operation. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  FIG. 6 is an explanatory diagram for explaining the reduced-cylinder operation before the intake valve stop control is executed in the second embodiment of the present invention. As shown in this figure, in the reduced-cylinder operation, by using the variable valve mechanisms 38 and 40 on the intake side and the exhaust side, the intake valve 34 and the exhaust gas in the control target cylinder (or a part of the cylinders including this). The valve 36 is held in the valve stop state, and the fuel injection of the cylinder is stopped. This reduced-cylinder operation is executed, for example, during a light load operation or the like according to the operating state of the internal combustion engine.

  In the present embodiment, when the internal combustion engine is decelerated during the reduced cylinder operation, the exhaust valve 36 of the cylinder to be controlled is returned to the normal open and closed states. At this time, since the intake valve 34 and the fuel injection of the control target cylinder are held in a stopped state, the control target cylinder is in a state in which the same intake valve stop control as that in the first embodiment is executed. On the other hand, in the non-control target cylinder, as in the first embodiment, the intake air amount is reduced as much as possible within a range where combustion is established, and the fuel injection amount is controlled in accordance with the intake air amount.

[Specific Processing for Realizing Embodiment 2]
FIG. 7 is a flowchart showing the control executed by the ECU in the second embodiment of the present invention. In the routine shown in FIG. 7, first, in steps 200 and 202, it is determined whether or not the vehicle has been decelerated by performing the same processing as in steps 100 and 102 of the first embodiment. When it is determined that the vehicle is decelerating, the intake valve stop control is executed in the cylinder by returning the exhaust valve 36 of the cylinder that is in the reduced cylinder operation to the normal open / closed state (step 204). ). On the other hand, when it is determined that the vehicle is not decelerating, normal reduced-cylinder operation is continued (step 206).

  In the present embodiment configured as described above, it is possible to obtain substantially the same operational effects as in the first embodiment. And especially in this Embodiment, this invention is applicable also to the cylinder which performs a reduced cylinder driving | operation.

Embodiment 3 FIG.
Next, Embodiment 3 of the present invention will be described with reference to FIGS. The feature of this embodiment is that an exhaust throttle valve is provided in the exhaust passage as one of the exhaust pressure increasing means. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  FIG. 8 is an explanatory diagram for illustrating intake valve stop control during deceleration in the third embodiment of the present invention. As shown in FIG. 8, an electric exhaust throttle valve 90 is provided in the exhaust passage 22. The exhaust throttle valve 90 opens and closes the exhaust passage 22 in accordance with a control signal input from the ECU 50. Is configured to do. Further, the exhaust throttle valve 90 is provided in a joining portion where exhaust pipes connected to the respective cylinders join in the exhaust passage 22.

  In this embodiment, when the internal combustion engine is decelerated, the exhaust throttle valve 90 is further closed while executing the same intake valve stop control as in the first embodiment. More specifically, the exhaust throttle valve 90 is closed when the exhaust valve 36 of the cylinder to be controlled is closed, and the exhaust pressure is further increased at this timing.

[Specific Processing for Realizing Embodiment 3]
FIG. 9 is a flowchart showing the control executed by the ECU in the third embodiment of the present invention. In the routine shown in FIG. 9, first, in steps 300 and 302, it is determined whether or not the vehicle has been decelerated by performing the same processing as in steps 100 and 102 of the first embodiment. When it is determined that the vehicle is in a deceleration state, intake valve stop control is executed, and the exhaust throttle valve 90 is closed at the timing when the exhaust valve 36 of the control target cylinder is closed. On the other hand, when it is determined that the vehicle is not decelerating, the normal operation state is continued while the exhaust throttle valve 90 is kept open (step 306).

  In the present embodiment configured as described above, it is possible to obtain substantially the same operational effects as in the first embodiment. In particular, in the present embodiment, the exhaust throttle valve 90 is provided. Therefore, when the exhaust valve 36 of the cylinder to be controlled is closed, a part of the exhaust passage 22 is closed by the exhaust throttle valve 90, and the closed space. The exhaust pressure inside can be further increased. As a result, the in-cylinder pressure of the cylinder to be controlled can be efficiently increased, and oil rise can be reliably suppressed.

Embodiment 4 FIG.
Next, a fourth embodiment of the present invention will be described with reference to FIG. A feature of the present embodiment is that in any of the first to third embodiments, when the intake valve stop control is executed, the opening / closing timing (phase) of the exhaust valve of each cylinder is advanced. is there. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[Specific processing for realizing Embodiment 4]
FIG. 10 is a flowchart showing the control executed by the ECU in the fourth embodiment of the present invention. The routine shown in this figure is performed in parallel with any of the control routines (FIGS. 5, 7, and 9) of the first to third embodiments. In the routine shown in FIG. 10, it is first determined whether or not it is the execution timing of the intake valve stop control (step 400). When this determination is established, the VVT 42 is operated to advance the opening / closing timing of the exhaust valve 36 in all cylinders more than usual (step 402). On the other hand, when the determination in step 400 is not established, the exhaust valve 36 is operated at a normal opening / closing timing (step 404).

  According to this embodiment configured as described above, the following effects can be obtained in addition to the functions and effects of the first to third embodiments. That is, in the cylinder to be controlled, more exhaust gas can be introduced into the combustion chamber 16 at an earlier time as the opening timing of the exhaust valve 36 becomes earlier. Thereby, the in-cylinder pressure of the cylinder to be controlled can be reliably increased and oil rise can be suppressed.

  Further, in the non-control target cylinder, higher-pressure exhaust gas can be discharged to the exhaust passage 22 by an amount corresponding to the earlier opening timing of the exhaust valve 36. Thereby, high-pressure exhaust gas can be supplied to the cylinder to be controlled. In the present embodiment, the opening / closing timing of the exhaust valve 36 is advanced from the normal angle in all cylinders. However, the present invention is not limited to this, and the opening / closing timing of the exhaust valve 36 may be advanced only by the control target cylinder, and the exhaust valve 36 may be operated at the normal opening / closing timing in the non-control target cylinder.

Embodiment 5 FIG.
Next, a fifth embodiment of the present invention will be described with reference to FIG. The feature of this embodiment is that, in any of the first to third embodiments, the cylinder selected as the control target cylinder is changed every time the intake valve stop control is executed. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[Specific Processing for Realizing Embodiment 5]
FIG. 11 is a flowchart showing the control executed by the ECU in the fifth embodiment of the present invention. The routine shown in this figure is performed in parallel with any of the control routines (FIGS. 5, 7, and 9) of the first to third embodiments. In the routine shown in FIG. 11, it is first determined whether or not it is the execution timing of the intake valve stop control (step 500). When this determination is established, a cylinder to be controlled in the current intake valve stop control is selected from the four cylinders (step 502).

  Here, in the selection process of step 502, the control target cylinder is changed so that the current control target cylinder is different from the control target cylinder at the time of the previous execution of the intake valve stop control. For example, if the previous control target cylinders are # 1 and # 4 cylinders, # 2 and # 3 cylinders are selected as the current control target cylinders, and the remaining # 1 and # 4 cylinders are selected. The cylinder is a non-control target cylinder in the current intake valve stop control. The ECU 50 is configured to store the control target cylinder at that time each time the intake valve stop control is executed.

  According to this embodiment configured as described above, the following effects can be obtained in addition to the functions and effects of the first to third embodiments. That is, every time the intake valve stop control at the time of deceleration is performed, the cylinders to be controlled can be changed sequentially, so that the frequency and amount of oil rise can be equalized for each cylinder. As a result, for example, it is possible to avoid oil concentration from occurring intensively in a specific cylinder, and deposits and the like due to oil in the cylinder. That is, in all the cylinders, oil rise can be suppressed evenly, and the operational effects of the first to third embodiments can be stably exhibited in each cylinder.

  In the first to third embodiments, step 104 in FIG. 5, step 204 in FIG. 7, and step 304 in FIG. 9 show specific examples of the partial cylinder stopping means. In the second embodiment, step 206 in FIG. 7 shows a specific example of the reduced cylinder operation means. Further, in the fourth embodiment, step 402 in FIG. 10 shows a specific example of the exhaust valve advance means, and in the fifth embodiment, step 502 in FIG. 11 shows a specific example of the target cylinder switching means. .

  In the embodiment, a four-cylinder internal combustion engine has been described as an example. However, the present invention is not limited to this and can be applied to an internal combustion engine having three or less cylinders or five or more cylinders. Further, the present invention is not limited to the embodiment with respect to the number of control target cylinders with respect to the total number of cylinders and combinations of cylinders to be controlled. That is, for example, the # 1 cylinder and the # 2 cylinder may be combined to be a control target cylinder, or only one of the four cylinders may be a control target cylinder. This applies to the case where the present invention is applied to a multi-cylinder engine other than four cylinders.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Cylinder 16 Combustion chamber 20 Intake passage 22 Exhaust passage 26 Throttle valve 30 Fuel injection valve 32 Spark plug 34 Intake valve 36 Exhaust valve 38 Intake variable valve mechanism 40 Exhaust variable valve mechanism 42 VVT
46 Accelerator sensor 48 Vehicle speed sensor 50 ECU
90 Exhaust throttle valve (exhaust pressure increasing means)

Claims (7)

An intake variable valve mechanism provided in at least some of the plurality of cylinders of the internal combustion engine and capable of holding the intake valve of the cylinder in a valve stop state;
When the internal combustion engine is in a specific operation state including deceleration, the intake valve is held in the valve stop state and the exhaust valve is normally opened and closed only by the control target cylinder that is at least part of the plurality of cylinders. A partial cylinder stopping means for maintaining the state and stopping fuel injection of the cylinder;
Exhaust pressure increasing means for increasing the pressure of the exhaust passage of the internal combustion engine when the exhaust stroke of the cylinder to be controlled is performed;
A control device for an internal combustion engine, comprising:   The control apparatus for an internal combustion engine according to claim 1, wherein the exhaust pressure increasing means is exhaust gas discharged from other cylinders excluding the cylinder to be controlled.   The control device for an internal combustion engine according to claim 2, wherein the control target cylinder is selected from the plurality of cylinders so that an exhaust valve of the control target cylinder is closed during an exhaust stroke of the other cylinder. . An exhaust variable valve mechanism provided in at least some of the plurality of cylinders and capable of holding an exhaust valve of the cylinder in a valve stop state;
A reduced-cylinder operation means for performing a reduced-cylinder operation for stopping the intake valve, the exhaust valve, and fuel injection in a part of the cylinders including the control target cylinder,
2. The partial cylinder stopping means is configured to return an exhaust valve of the cylinder to be controlled to a normal open / closed state when an internal combustion engine enters the specific operation state during the reduced-cylinder operation. 4. The control device for an internal combustion engine according to any one of items 1 to 3.   5. An exhaust valve advance means for at least opening / closing timing of an exhaust valve of the control target cylinder more than usual when the intake valve of the control target cylinder is in a valve deactivation state. The control device for an internal combustion engine according to any one of the preceding claims.   The control apparatus for an internal combustion engine according to any one of claims 1 to 5, wherein the exhaust pressure increasing means includes an exhaust throttle valve provided in the exhaust passage so as to be openable and closable.   A cylinder that is selected as the control target cylinder among the plurality of cylinders is changed each time the specific operation state appears, and a target cylinder switching unit that performs normal combustion in cylinders other than the control target cylinder is provided. Item 7. The control device for an internal combustion engine according to any one of Items 1 to 6.

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