JP2016089812A - Variable cylinder control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the deterioration of exhaust emission when starting full-cylinder operation after finishing reduced-cylinder operation.MEANS FOR SOLVING THE PROBLEM: There is provided a variable cylinder control device of an internal combustion engine which comprises first and second exhaust passages which are independent at a part or remaining cylinders, and a variable valve mechanism which makes variable an operation characteristic of a suction/exhaust valve of a part of the cylinders. The variable cylinder control device comprises a cylinder control part which performs either of a full-cylinder operation and a reduced-cylinder operation for making a part of the cylinders pause, and a dynamic valve control part for controlling the variable valve mechanism. In the reduced-cylinder operation, the dynamic valve control part maintains a suction valve of a part of the cylinders in a valve-closed state, and slightly lifts an exhaust valve of a part of the cylinders so that an exhaust gas in the first exhaust passage is sucked into a part of the cylinders. In the reduced-cylinder operation, when an amount (ΣGb) of the exhaust gas which is consumed from the first exhaust passage exceeds a prescribed amount (α), the cylinder control part stops the reduced-cylinder operation (S207).SELECTED DRAWING: Figure 14

Description

  The present invention relates to a variable cylinder control device for an internal combustion engine, and in particular, all cylinder operation in which all cylinders are operated during operation of the internal combustion engine, and reduced cylinder operation in which some cylinders are deactivated and the remaining cylinders are operated. The present invention relates to a variable cylinder control device for an internal combustion engine capable of executing one of operation and operation.

  In order to improve the fuel consumption of an internal combustion engine, it is known that when a predetermined condition is satisfied, a part of all cylinders is deactivated and the remaining cylinders are operated to perform a reduced cylinder operation. In addition, if the in-cylinder pressure of the idle cylinders, which are some cylinders, greatly deviates from the desired target pressure during reduced-cylinder operation, the rotational fluctuation of the crankshaft of the internal combustion engine increases and the noise vibration (NV) performance of the internal combustion engine deteriorates. To do. For this reason, an in-cylinder pressure of a deactivated cylinder is controlled by appropriately opening an intake valve or an exhaust valve of the deactivated cylinder (see, for example, Patent Document 1).

JP 2005-172001 A

  In some internal combustion engines, exhaust passages are provided independently for each of the deactivated cylinder and the active cylinder. Further, during the reduced cylinder operation, the intake valve is maintained in the closed state in the idle cylinder, and the exhaust valve is in an exhaust state on the idle cylinder side in a state where at least one of the lift amount and the working angle is smaller than in the full cylinder operation. It is conceivable to open the valve at a timing such that the exhaust gas in the passage is sucked into the idle cylinder.

  In this case, if the execution time of the reduced cylinder operation is too long, the exhaust gas existing in the exhaust passage on the idle cylinder side is sucked into the idle cylinder and consumed, and the reduced cylinder operation is performed. There is a problem that exhaust emission deteriorates when all cylinder operation is started after completion.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to provide a variable cylinder control device for an internal combustion engine that can suppress deterioration of exhaust emission when the reduced cylinder operation is finished and the all cylinder operation is started. Is to provide.

According to one aspect of the invention,
The first exhaust passage and the second exhaust passage provided independently for each of some of the cylinders and the remaining cylinder, and the operating characteristics of the intake valves and exhaust valves of at least some of the cylinders. A variable cylinder control device for an internal combustion engine comprising a variable valve mechanism for making it variable,
A cylinder controller configured to perform one of an all-cylinder operation in which all the cylinders are operated during the operation of the internal combustion engine and a reduced cylinder operation in which the remaining cylinders are deactivated and the remaining cylinders are operated; ,
A valve control unit configured to control the variable valve mechanism;
With
The valve control unit maintains the intake valves of the some cylinders in a closed state during the reduced-cylinder operation, and sets the exhaust valves of the some cylinders so that at least one of the lift amount and the operating angle is all cylinders. Controlling the variable valve mechanism so that the valve is opened so that the exhaust gas in the first exhaust passage becomes less than during operation and is sucked into the some cylinders;
The variable cylinder control device for an internal combustion engine, wherein the cylinder control unit stops the cylinder reduction operation when the amount of exhaust gas consumed from the first exhaust passage exceeds a predetermined amount during the cylinder reduction operation. Is provided.

  According to the present invention, it is possible to suppress the deterioration of exhaust emission when the reduced cylinder operation is finished and the all cylinder operation is started.

It is the schematic which shows the structure which concerns on 1st Embodiment of this invention. It is a perspective view of a valve lift variable mechanism. It is sectional drawing of a valve lift variable mechanism, and shows a state when a cam lobe member exists in a protrusion position. It is sectional drawing of a valve lift variable mechanism, and shows a state when a cam lobe member exists in a storing position. It is a valve lift diagram of a 1st embodiment. It is sectional drawing for demonstrating the action | operation of a valve lift variable mechanism. It is sectional drawing for demonstrating the action | operation of a valve lift variable mechanism. It is sectional drawing for demonstrating the action | operation of a valve lift variable mechanism. It is sectional drawing for demonstrating the action | operation of a valve lift variable mechanism. It is sectional drawing for demonstrating the action | operation of a valve lift variable mechanism. It is sectional drawing for demonstrating the action | operation of a valve lift variable mechanism. It is a diagram for showing changes in in-cylinder pressure and crankshaft rotation speed. It is a flowchart regarding the routine for performing cylinder pressure control of a dormant cylinder. It is a flowchart regarding the routine for performing temporary stop of reduced-cylinder operation. It is a valve lift diagram of a 2nd embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[First Embodiment]
FIG. 1 schematically shows a variable cylinder control device for an internal combustion engine according to a first embodiment of the present invention. An illustrated internal combustion engine (engine) 1 is a V-type 6-cylinder spark ignition internal combustion engine (gasoline engine). The engine 1 has a first bank A and a second bank B. The first bank A is provided with odd-numbered cylinders, that is, # 1, # 3, and # 5 cylinders, and the second bank B has Even-numbered cylinders, that is, # 2, # 4, and # 6 cylinders are provided. The # 1, # 3, and # 5 cylinders constitute “a part of the cylinder” according to the present invention, and the # 2, # 4, and # 6 cylinders constitute the “remaining cylinder” according to the present invention. That is, the first bank A includes # 1, # 3, and # 5 cylinders that are deactivated during the reduced cylinder operation, and the second bank B is # 2 that is the active cylinder during the reduced cylinder operation. , # 4, # 6 cylinders are included. Of course, all cylinders # 1 to # 6 are operated during the operation of all cylinders. For convenience, the # 1, # 3, and # 5 cylinders are sometimes referred to as “rest cylinders”, and the # 2, # 4, and # 6 cylinders are sometimes referred to as “working cylinders”. The engine of this embodiment is mounted on a vehicle. However, the use, type, and form of the engine are arbitrary.

  The intake passage 2 for sucking fresh air into the cylinder of each cylinder includes an intake pipe 3, a surge tank 4, an intake manifold 5, and an intake port 6 provided in this order from the upstream side. The intake pipe 3 is provided with an air flow meter 7 and an electronically controlled throttle valve 8 in order from the upstream side. The air flow meter 7 outputs a signal having a magnitude corresponding to the intake air amount per unit time, that is, the intake flow rate. Each cylinder is provided with an injector (fuel injection valve) 9 for injecting fuel into the intake port 6 and an ignition plug 10 for igniting the air-fuel mixture in the cylinder.

  As for the exhaust passage for exhausting exhaust gas from the cylinder, in the present embodiment, the first exhaust passage 11A for the first bank A and the second exhaust passage 11B for the second bank B are independent of each other. Is provided. That is, the engine 1 includes first and second exhaust passages 11A and 11B provided independently for the # 1, # 3, # 5 cylinder and the # 2, # 4, # 6 cylinder, respectively. Since both banks have the same exhaust system configuration including the exhaust passages 11A and 11B, only the first bank A will be described here, and for the second bank B, the last symbol in the figure is replaced from A to B. Therefore, the description is omitted.

  The first exhaust passage 11A includes, in order from the upstream side, the exhaust ports 12A of the cylinders # 1, # 3, and # 5, the exhaust manifold 13A that collects the exhaust gas of these exhaust ports 12A, and the collecting portion of the exhaust manifold 13A. And an exhaust pipe 14A connected to the downstream end. A three-way catalyst having an oxygen storage capacity, that is, an upstream catalyst 15A and a downstream catalyst 16A are provided in series on the upstream side and the downstream side of the exhaust pipe 14A. The gas passages in the upstream catalyst 15A and the downstream catalyst 16A are also included in the first exhaust passage 11A. An exhaust pipe 14A on the upstream side of the upstream catalyst 15A is provided with an air-fuel ratio sensor 17A for detecting the air-fuel ratio of the exhaust gas.

  The throttle valve 8, the injector 9, and the spark plug 10 are electrically connected to an electronic control unit (hereinafter referred to as ECU) 100 that constitutes a control unit. The ECU 100 includes a CPU, a ROM, a RAM, an input / output port, a storage device, and the like, all not shown. In addition to the air flow meter 7 and the air-fuel ratio sensors 17A and 17B, the ECU 100 includes a crank angle sensor 18 for detecting the crank angle of the engine 1, an accelerator opening sensor 19 for detecting the accelerator opening, An in-cylinder pressure sensor 20 for detecting the in-cylinder pressure of the cylinder and other various sensors are electrically connected via an A / D converter or the like (not shown). The ECU 100 controls the throttle valve 8, the injector 9, the spark plug 10, and the like so as to obtain a desired output based on detection values of various sensors, and the like, and controls the fuel injection amount, fuel injection timing, throttle opening, ignition Control time etc.

  The ECU 100 detects the crank angle of the engine 1 based on the output of the crank angle sensor 18 and calculates the rotational speed of the engine. Here, the rotation speed (rpm) per minute is used as the engine rotation speed. Further, the ECU 100 calculates the engine load based on the output of the air flow meter 7.

  Further, the ECU 100 causes the air-fuel ratio (specifically, the air-fuel ratio (specifically, A / F = 14.6), which is a predetermined target air-fuel ratio, to be close to the air-fuel ratio detected by the air-fuel ratio sensors 17A and 17B. The fuel injection amount) is feedback controlled. This air-fuel ratio control is performed individually for each bank. That is, the air-fuel ratio control of the # 1, # 3, and # 5 cylinders belonging to the first bank A is performed based on the output of the air-fuel ratio sensor 17A on the first bank A side. On the other hand, the air-fuel ratio control of the # 2, # 4, and # 6 cylinders belonging to the second bank B is performed based on the output of the air-fuel ratio sensor 17B on the second bank B side.

  The ECU 100 also operates all cylinders to operate all cylinders while the engine 1 is in operation, and pauses # 1, # 3, and # 5 cylinders (first bank A) among all cylinders # 2, # 4, # It is configured to execute one of the reduced-cylinder operation in which 6 cylinders (second bank B) are operated, and constitutes a “cylinder control unit” according to the present invention. Specifically, the ECU 100 causes the engine to operate in all cylinders when a predetermined reduced-cylinder operation condition is not satisfied, that is, during normal operation, and causes the engine to perform a reduced-cylinder operation when the reduced-cylinder operation condition is satisfied. During all cylinder operation, the ECU 100 causes the fuel injection by the injector 9 and the ignition by the spark plug 10 to be executed in all cylinders so that all the cylinders are in operation. On the other hand, during the reduced-cylinder operation, the ECU 100 executes fuel injection and ignition in the # 2, # 4, and # 6 cylinders (second bank B), while operating these cylinders, while # 1, # 3, In the # 5 cylinder (first bank A), fuel injection and ignition are stopped, and the cylinders are stopped.

  Further, the engine 1 of the present embodiment includes a first variable valve mechanism 30A for making the operating characteristics of the intake valves and exhaust valves of the # 1, # 3, and # 5 cylinders variable, and # 2, # 4, A second variable valve mechanism 30B is provided for making the operating characteristics of the # 6 cylinder intake valve and exhaust valve variable. Here, the “operation characteristic” includes at least one of lift, operating angle, and valve timing (open and close timing). The ECU 100 is configured to control these variable valve mechanisms 30A and 30B, and constitutes a “valve control unit” according to the present invention.

  The first variable valve mechanism 30A includes a first intake-side variable valve mechanism 31A and a first exhaust-side variable valve mechanism 32A. Similarly, the second variable valve mechanism 30B includes a second intake-side variable valve mechanism 31B and a second exhaust-side variable valve mechanism 32B. First, the first exhaust side variable valve mechanism 32A will be described.

  The first exhaust side variable valve mechanism 32A includes a variable valve timing mechanism 33 for changing the opening / closing timing of the exhaust valves of the # 1, # 3, and # 5 cylinders. The variable valve timing mechanism 33 changes the relative rotational phase of the camshaft with respect to the crankshaft. Since the variable valve timing mechanism 33 is well-known and will not be described in detail, the mechanism generally includes an input side member that is rotationally driven by a crankshaft via a power transmission mechanism such as a belt and a pulley, and a camshaft. And changing the rotational phase difference between the input side member and the output side member to uniformly change the opening / closing timings of the exhaust valves of the respective cylinders. The valve timing variable mechanism 33 is controlled by the ECU 100.

  The first exhaust-side variable valve mechanism 32A includes a variable valve lift mechanism 40 as shown in FIGS. The variable valve lift mechanism 40 includes the cam shaft 41 described above and a cam unit 42 provided on the cam shaft 41 for each cylinder. The cam is not provided on the camshaft 41 itself, and the cam is provided on the cam unit 42. The camshaft 41 is divided at the positions of the cylinders # 1, # 3, and # 5, and a cam unit 42 is coaxially connected to the divided portion. However, the installation method of the cam unit 42 is arbitrary. As shown in FIGS. 3, 4, and 6, the cam unit 42 simultaneously lifts the two exhaust valves 25 per cylinder through the individual rocker arms 24 during rotation in the rotation direction R. ing. In addition, 26 is a valve spring, 27 is a hydraulic lash adjuster. Two intake valves are also provided per cylinder.

  The cam unit 42 includes a cam base member 43 having a diameter larger than that of the cam shaft 41 and two cam lobe members 44 coupled to the cam base member 43 so as to be swingable or turnable. The two cam lobe members 44 correspond to the two exhaust valves 25.

  The cam base member 43 has a substantially cylindrical shape, and has a substantially circular base circle 45 when viewed from the direction of the central axis X of the cam shaft 41 (hereinafter simply referred to as the axial direction). The base circle 45 corresponds to the outer peripheral surface of the cam base member 43. Two base circular portions 45 are also provided corresponding to the two exhaust valves 25. Each base circular portion 45 is provided with a slit 46, and a cam lobe member 44 is inserted into each slit 46. The cam lobe member 44 has a substantially U-shape or L-shape (so-called boomerang shape) as shown in FIGS. 3 and 4.

  In the cam base member 43, a recess 47 is formed between the two base circles 45. A support shaft 48 is provided so as to penetrate the cam base member 43 in the axial direction. The support shaft 48 is inserted into a shaft hole 49 at the base end portion of the cam lobe member 44. Thereby, the cam lobe member 44 can turn or swing around the support shaft 48.

  The cam lobe member 44 protrudes to the maximum extent from the base circle 45 of the cam base member 43 (shown in FIG. 3) and is stored in the base circle 45 without protruding from the base circle 45 (FIG. 4). ). The two cam lobe members 44 are respectively provided with stopper pins 50 protruding in the axial direction, and these stopper pins 50 are slidably inserted into the long holes 51 provided in the cam base member 43. The movement of the stopper pin 50 is restricted by the long hole 51, and as a result, the swing range, the protruding position, and the retracted position of the cam lobe member 44 are defined. As will be described in detail later, the cam lobe member 44 is locked at either the protruding position or the retracted position.

  In FIG. 2, for the sake of convenience, the cam lobe member 44 located in the axially forward Fr is in the retracted position and the cam lobe member 44 located in the axially rearward Rr is in the protruding position, but both cam lobe members 44 are actually the same. Located in position.

  The recess 47 is provided with two springs 52 and 52 for urging the two cam lobe members 44 toward the protruding positions. These springs 52 and 52 form urging members. The spring 52 is a coil spring and is wound around the outside of the support shaft 33. A base end portion of the spring 52 is fixed to the cam base member 43 via a fixed shaft 53. The tip end of the spring 52 is engaged with the stopper pin 50, and the stopper pin 50 and thus the cam lobe member 44 are urged toward the protruding position.

  In particular, the base circle portion 45 is provided with a cam nose portion 55 that projects the exhaust valve 25 in a small radial direction when the cam lobe member 44 is in the retracted position. However, as shown in FIG. 3, when the cam lobe member 44 is in the protruding position, the lift amount by the cam lobe member 44 is equal to or greater than the lift amount by the cam nose portion 55, and the cam nose portion 55 does not interfere with the lift by the cam lobe member 44 in the protruding position. It is like that.

  As schematically shown in FIG. 6, the rocker arm 24 is disposed so as to be in contact with a portion of the base circle 45 adjacent to the cam lobe member 44 or the slit 46 in the axial direction. As shown in FIGS. 3 and 4, when the rocker arm 24 is in contact with the base circle portion 45 excluding the cam nose portion 55, the lift amount of the exhaust valve becomes zero. On the other hand, when the rocker arm 24 comes into contact with the cam lobe member 44 at the protruding position, the lift amount of the exhaust valve becomes a value larger than zero corresponding to the protruding amount of the cam lobe member 44. When the cam lobe member 44 is in the retracted position and the rocker arm 24 is in contact with the cam nose portion 55, the lift amount of the exhaust valve is greater than zero according to the amount of protrusion of the cam nose portion 55, but at the protrusion position. It is smaller than when it contacts a certain cam lobe member 44.

  FIG. 5 shows a valve lift diagram of the present embodiment. In particular, attention should be paid to lines L1 and L2 indicating valve lift diagrams of the exhaust valves of # 1, # 3, and # 5 cylinders.

  When the cam lobe member 44 is locked at the protruding position, the valve lift diagram of the exhaust valve is as shown by a line L1. That is, a relatively large lift amount and operating angle are exhibited in accordance with the state during normal all-cylinder operation. The exhaust valve opens from the latter stage of the expansion stroke to the initial stage of the intake stroke immediately after the exhaust top dead center (exhaust TDC) through the exhaust stroke. In other words, the profile of the cam lobe member 44 and the base circle 45 is formed so that such a state is realized.

  On the other hand, when the cam lobe member 44 is locked in the retracted position, the valve lift diagram of the exhaust valve is as shown by line L2. That is, corresponding to the state during the reduced cylinder operation, the lift amount and the operating angle are smaller than those during the all cylinder operation. The exhaust valve is opened only in a part of the expansion stroke (particularly in the later stage). In other words, the profile of the base circle portion 45 (including the cam nose portion 55) is formed so that such a state is realized. The base circle portion 45 has a constant radius around the central axis X corresponding to the zero lift amount except for the cam nose portion 55.

  Here, lines L1 and L2 indicate states when the valve timing of the exhaust valve is retarded to the maximum by the valve timing variable mechanism 33. Valve lift diagrams when the valve timing of the exhaust valve is advanced to the maximum are as indicated by lines L1 'and L2'. As described above, the valve timing of the exhaust valve can be arbitrarily changed within the range from the lines L1 'and L2' to the lines L1 and L2. In particular, when the cam lobe member 44 is in the retracted position, the valve opening period (or range of operating angle) of the exhaust valve is changed to approach or move away from the expansion bottom dead center (expansion BDC) within the expansion stroke range. Is possible.

  Next, the configuration of the locking mechanism for locking the cam lobe member 44 to the protruding position or the retracted position and the operation of the variable valve lift mechanism 40 will be described with reference to FIGS. 6 to 11 schematically represent the VI-VI cross section of FIG. 3 in each state.

  FIG. 6 shows a state where the cam lobe member 44 as shown in FIG. 3 is in the protruding position. Here, as can be understood from the above description and related drawings, the cam unit 42 is configured to be symmetrical in the longitudinal direction in the axial direction. Accordingly, only the configuration on the front side will be described here.

  A supply path 61 extending along the central axis X is provided inside the camshaft 41 and the cam base member 43. In the cam base member 43, paths 62 and 63 extending radially outward from the supply path 61 at different angular positions around the central axis X are formed. The paths 62 and 63 extend radially outward and then turn in the axial direction toward the slit 46.

  Inside the cam base member 43, a pin hole 64H communicating with the path 62 and a pin hole 65H coaxial with the pin hole 64H and having the same diameter are provided. The pin hole 65H is located at a position facing the pin hole 64H across the slit 46. A pin hole 66H having the same diameter as the pin hole 64H is also provided at the tip of the cam lobe member 44. Pins 64P, 65P, 66P having the same diameter are slidably inserted into the pin holes 64H, 65H, 66H, respectively. The pin hole 65H is provided with a spring 65S for urging the pin 65P toward the slit 46 side.

  The other path 63 is open to the slit 46. A pin hole 67 </ b> H is provided inside the cam base member 43, and the pin hole 67 </ b> H is in a coaxial position facing the slit 46 from the open end of the path 63. A pin 67P is slidably inserted into the pin hole 67H, and a compressible spring 67S that holds the pin 67P in the pin hole 67H is disposed. The pin hole 67H has the same diameter as the above-described pin holes 64H, 65H, and 66H, and the pin 67P has the same diameter as the above-described pins 64P, 65P, and 66P.

  By changing the engagement state of these pins 64P, 65P, 66P, 67P and the pin holes 64H, 65H, 66H, 67H, the cam lobe member 44 can be locked at the protruding position or the retracted position.

  Oil or hydraulic pressure is supplied to the supply path 61 from an oil pump 69 via an oil control valve (OCV) 68. The oil control valve 68 is an electromagnetically driven flow control valve and is controlled by the ECU 100. The oil pump 69 is a mechanical type driven by a crankshaft and supplies oil stored in an oil pan. However, the configuration for supplying oil to the supply path 61 may be other configurations, for example, the oil pump 69 may be electrically operated.

  FIG. 6 shows a state when the cam lobe member 44 is locked at the protruding position as shown in FIG. At this time, no oil is supplied to the supply path 61 (the hydraulic pressure is off), and the pin holes 66H of the cam lobe member 44 are aligned coaxially with the pin holes 64H and 65H of the cam base member 43 as shown in FIG. Has been. Due to the biasing force of the spring 65S, the pin 65P is commonly inserted in a state straddling the pin holes 65H and 66H, and the pin 66P is also commonly inserted in a state straddling the pin holes 66H and 64H. Thereby, the cam lobe member 44 is locked to the cam base member 43 at the protruding position. The pin 64P is completely inserted into the pin hole 64H.

  From this state, the operation when the cam lobe member 44 is moved to the storage position and locked to the storage position is as follows. First, as shown in FIG. 7, the oil control valve 68 is opened, and oil is supplied to the supply path 61 (hydraulic-on state). Then, due to the hydraulic pressure supplied from the path 62, the adjacent pins 64P, 65P, 66P are pushed forward against the urging force of the spring 65S, and the pins 65P, 66P engage with the pin holes 64H, 65H, 66H. Come off. That is, the three pins 64P, 65P, 66P are arranged only in the corresponding pin holes 64H, 65H, 66H, respectively. As a result, the lock of the cam lobe member 44 is released, and the cam lobe member 44 can move toward the storage position.

  When the cam base member 43 rotates and the cam lobe member 44 rides on the rocker arm 24 in this state, the cam lobe member 44 is pushed by the rocker arm 24 (specifically, by the valve spring reaction force) and gradually moves to the retracted position. . During this movement, the cam lobe member 44 carries the pin 66P while holding the pin 66P in its own pin hole 66H.

  FIG. 8 shows a state at the moment when the cam lobe member 44 reaches the storage position. At this time, the pin hole 66H at the tip of the cam lobe member 44 is aligned with the pin hole 67H of the cam base member 43.

  Since the hydraulic pressure is still on, when the cam lobe member 44 reaches the retracted position, the pins 66P and 67P compress the spring 67S by the hydraulic pressure from the other path 63 as shown in FIG. While being pushed forward, the pin 66P is inserted in common in a state straddling the pin holes 67H and 66H. Thereby, as shown also in FIG. 4, the cam lobe member 44 is locked to the cam base member 43 in the retracted position. The pin 67P is completely inserted into the pin hole 67H. In order to keep the cam lobe member 44 locked in the retracted position, it is necessary to maintain the hydraulic pressure on.

  Next, the operation when the cam lobe member 44 is moved from the retracted position to the protruding position and locked to the protruding position will be described.

  First, the hydraulic pressure is turned off from the state shown in FIG. That is, the oil control valve 68 is closed, the supply of oil to the supply path 61 is stopped, and the oil is discharged from the supply path 61. Then, as shown in FIG. 10, the pins 66P and 67P are pushed backward by the spring 67S, and the engagement of the pin 66P with the pin hole 67H is released. That is, the two pins 66P and 67P are arranged only in the corresponding pin holes 66H and 67H, respectively. Thereby, the lock of the cam lobe member 44 is released, and the cam lobe member 44 can move toward the protruding position.

  When the cam base member 43 is rotated in this state, the cam lobe member 44 is detached from the rocker arm 24, and the base circle 45 of the cam base member 43 rides on the rocker arm 24, the cam lobe member 44 is gradually projected by the biasing force of the spring 52. Move to. During this movement, the cam lobe member 44 carries the pin 66P while holding the pin 66P in its own pin hole 66H.

  FIG. 11 shows a state at the moment when the cam lobe member 44 reaches the protruding position. At this time, the pin hole 66H of the cam lobe member 44 is aligned with the pin holes 64H and 65H of the cam base member 43.

  Then, as shown in FIG. 6, the pins 64P, 65P, 66P are pushed backward by the urging force of the spring 65S, and the pin 65P is inserted in a state straddling the pin holes 65H, 66H. It is inserted in common in the state straddling the holes 66H and 64H. Thereby, the cam lobe member 44 is locked to the cam base member 43 at the protruding position. As long as the hydraulic pressure is off, the cam lobe member 44 is kept locked in the protruding position.

  In summary, the cam lobe member 44 is held at the protruding position when the hydraulic pressure is off, and is held at the retracted position when the hydraulic pressure is on.

  Next, the first intake side variable valve mechanism 31A shown in FIG. 1 will be described. The first intake side variable valve mechanism 31A is configured in substantially the same manner as the first exhaust side variable valve mechanism 32A described above, but is different in that the cam nose portion 55 is not provided in the base circle portion 45. 1 different from the exhaust side variable valve mechanism 32A.

  In FIG. 5, the valve lift diagrams of the intake valves of the # 1, # 3, and # 5 cylinders are as shown by lines L3 and L4. In particular, when the cam lobe member 44 is locked at the retracted position, the lift amount of the intake valve is always zero as shown by the line L4, and the intake valve is maintained in the closed state. This is because there is no cam nose portion 55.

  Since the first intake side variable valve mechanism 31A is also provided with the variable valve timing mechanism 33, the valve timing of the intake valve when the cam lobe member 44 is in the protruding position is within the range from the line L3 ′ to the line L3. Can be changed arbitrarily.

  Next, the second intake side variable valve mechanism 31B and the second exhaust side variable valve mechanism 32B shown in FIG. 1 will be described. These variable valve mechanisms 31B and 32B have substantially the same configuration as each other, and include a variable valve timing mechanism 33, but do not include a cam unit 42 and thus a variable valve lift mechanism. That is, as usual, the camshaft 41 ′ is connected to the output side member of the variable valve timing mechanism 33, and the cam lobe corresponding to each intake valve or exhaust valve is fixed to the camshaft 41 ′. Therefore, the variable valve mechanisms 31B and 32B can change only the valve timings of the intake valve and the exhaust valve. The valve lift diagrams of the intake valves and exhaust valves of cylinders # 2, # 4, and # 6 are as shown by L3 and L1 in FIG. 5 (however, variable to L3 'and L1').

  As described above, in the present embodiment, the ECU 100 controls the first intake side and exhaust so that the cam lobe member 44 is positioned at the protruding position during all cylinder operation and the cam lobe member 44 is positioned at the retracted position during reduced cylinder operation. The variable valve lift mechanism 40 of the side variable valve mechanisms 31A and 32A is controlled.

  In general, in an internal combustion engine capable of reducing cylinder operation, it is preferable to adjust or control the in-cylinder pressure of the idle cylinder to an optimum value during the reduced cylinder operation. This is to suppress crankshaft rotation fluctuations and improve the noise vibration (NV) performance of the internal combustion engine.

  On the other hand, during the reduced-cylinder operation, it is conceivable to keep both the intake valve and the exhaust valve of the idle cylinder closed. However, in this case, due to a change in the cylinder pressure accompanying the vertical movement of the piston, gas leakage from the cylinder into the crankcase and gas suction from the crankcase into the cylinder are repeated through the gap between the piston ring and the cylinder inner wall. As a result, gas gradually leaks from the cylinder. As a result, the in-cylinder pressure of the idle cylinder normally converges to a relatively low pressure of about a fraction of the full load within a few to several tens of cycles (1 cycle = 720 ° CA) from the start of the reduced cylinder operation. To do. During the reduced-cylinder operation, the cylinder shaft pressure and cylinder gas amount (especially the total cylinder pressure and total cylinder gas amount) of the idle cylinder are set to the same level as those of the operating cylinder, so Although it is advantageous for improving the noise vibration performance of the engine, it is difficult to do so when both the intake valve and the exhaust valve of the idle cylinder are kept closed during the reduced-cylinder operation.

  Therefore, in this embodiment, the cam nose portion 55 is provided in the cam unit 42 of the idle cylinder (# 1, # 3, # 5 cylinder), and the exhaust valve is expanded during the reduced cylinder operation as shown in FIG. A small lift is made during the stroke (especially in the latter half). By doing so, an amount of exhaust gas corresponding to the leaked in-cylinder gas amount can be sucked into the cylinder from the first exhaust passage 11A and continuously replenished. This is because the pressure in the cylinder is lower than that of the first exhaust passage 11A in the expansion stroke (particularly in the latter stage). As a result, the cylinder pressure and cylinder gas amount of the idle cylinder can be maintained at optimum desired values. The exhaust gas in the first exhaust passage 11A referred to here is exhaust gas generated during all cylinder operation and staying in the first exhaust passage 11A.

  In this way, the ECU 100 that constitutes the valve operating control unit maintains the intake valve of the deactivated cylinder in the closed state during the reduced-cylinder operation, and the exhaust amount of the deactivated cylinder is higher than that during the operation of all cylinders. The first exhaust-side variable valve mechanism 32A is controlled so as to be opened so that the exhaust gas in the first exhaust passage 11A decreases and is taken into the idle cylinder.

  In FIG. 12, (A) is the in-cylinder pressure of the operating cylinder, (B) is the in-cylinder pressure of the idle cylinder, (C) is the fluctuation of the actual rotational speed of the crankshaft (that is, fluctuation in rotation), and (D) is the crankshaft pressure. Shows fluctuations in ideal rotation speed. Although the illustrated example is an example of an in-line four-cylinder engine, it will be understood that the following description applies similarly to the V-type six-cylinder engine of this embodiment and other types of engines. The illustrated example shows a state during reduced-cylinder operation.

  In the example of the in-line four-cylinder engine described here, the cylinder numbers are # 1, # 2, # 3, and # 4 in order from the front of the engine, the ignition order is # 1, # 3, # 4, and # 2, and the number is reduced. The active cylinders during cylinder operation are # 2, # 3, and the idle cylinders are # 1, # 4. The position (crank angle) of compression TDC of each cylinder is as shown in the lowermost stage of the figure. Regarding (B), it should be noted that the in-cylinder pressure rises even in the exhaust stroke because the exhaust valve is closed in the idle cylinder, and the in-cylinder pressures of the # 1 and # 4 cylinders are the same.

  In (B) and (C), line a shows the case of the comparative example, that is, the case where both the intake valve and the exhaust valve of the idle cylinder are kept closed during the reduced cylinder operation. A line b indicates the case of this embodiment. A line c indicates a case where the technique of the present embodiment is applied excessively and exhaust gas is excessively replenished in the cylinder.

  In the case of the comparative example, even if the in-cylinder pressure initial value of the idle cylinder at the start of the reduced cylinder operation is high, the in-cylinder gas leaks within several to several tens of cycles. Finally, it stabilizes in a low state (line a in (B)). On the other hand, in the case of the present embodiment, it is possible to keep the in-cylinder pressure of the idle cylinder higher than that of the comparative example (line b in (B)), and the actual rotational fluctuation of the crankshaft (of (C)). The line b) can be brought close to an ideal state as shown in (D). As a result, the rotational primary component (in the case of an in-line four-cylinder engine), which is normally a problem during reduced-cylinder operation, can be reduced, and noise vibration performance can be improved.

  However, if the technique of the present embodiment is applied excessively and the cylinder pressure of the idle cylinder is excessively increased (line c in (B)), the actual rotational fluctuation of the crankshaft (line c in (C)). Is larger than the ideal state as shown in (D), and the absolute value of the rotational secondary component increases, which is not preferable in terms of noise vibration performance. As described above, the cylinder internal pressure of the idle cylinder has an optimum value for each engine operating state.

  Therefore, in the present embodiment, as shown in FIG. 5B, during the reduced-cylinder operation, the ECU 100 controls the valve timing variable mechanism 33 in accordance with the engine operating state, so that the exhaust valve opening period or small lift is increased. The period can be changed in the approach / separation direction with respect to the expansion bottom dead center. By doing so, the in-cylinder pressure can be brought close to and maintained at a desired target pressure suitable for the engine operating state in the idle cylinder.

  The closer the exhaust valve opening period approaches the expansion bottom dead center, the lower the in-cylinder pressure relative to the exhaust passage internal pressure, that is, the greater the differential pressure between the in-cylinder pressure and the exhaust passage internal pressure, Inhaled. Therefore, the in-cylinder gas amount and the in-cylinder pressure tend to increase. On the contrary, the exhaust gas is sucked into the cylinder in a state where the differential pressure between the cylinder pressure and the exhaust passage pressure is smaller as the opening period of the exhaust valve is away from the expansion bottom dead center. Therefore, the in-cylinder gas amount and the in-cylinder pressure tend to decrease. However, since in-cylinder gas constantly leaks through the gap between the piston ring and the cylinder inner wall, whether or not the actual in-cylinder gas amount and in-cylinder pressure increase depends on the balance between the intake exhaust gas amount and the leakage amount.

  FIG. 13 shows a flowchart relating to a routine for performing in-cylinder pressure control of such a deactivated cylinder. The routine is repeatedly executed by the ECU 100 at every predetermined calculation cycle τ.

  In step S101, it is determined whether or not the reduced cylinder operation is being performed. If the reduced-cylinder operation is not being performed, the current process is terminated. If the reduced-cylinder operation is being performed, the process proceeds to step S102.

  In step S102, the actual engine speed Ne and load KL are acquired. The rotational speed Ne and the load KL are values as detection values calculated by the ECU 100.

  In step S103, a target in-cylinder gas amount Gt in the idle cylinder is calculated from a predetermined map based on the acquired value of the rotational speed Ne and the load KL. This target in-cylinder gas amount Gt is a value corresponding to the target in-cylinder pressure that can suppress the rotational fluctuation of the crankshaft and improve the noise vibration performance of the engine.

  In step S104, an estimated in-cylinder gas amount Ge, which is an estimated value of the actual in-cylinder gas amount in the idle cylinder, is calculated. In this case, the ECU 100 calculates the estimated in-cylinder gas amount Ge based on the in-cylinder pressure detected by the in-cylinder pressure sensor 20 of the deactivated cylinder (# 1, # 3, # 5 cylinder). Alternatively, the ECU 100 may calculate the estimated in-cylinder gas amount Ge based on a predetermined index value representing the variation amount of the engine rotation speed obtained from the crank angle sensor 18. In addition to these, various estimation methods are possible.

  In step S105, the estimated in-cylinder gas amount Ge is compared with the target in-cylinder gas amount Gt.

  When the estimated in-cylinder gas amount Ge is smaller than the target in-cylinder gas amount Gt, the process proceeds to step S106, and the target value Vt for controlling the valve timing variable mechanism 33 of the first exhaust-side variable valve mechanism 32A is further increased. It is changed or corrected to the value on the retard side (Vt + ΔV). Here, the valve timing is changed to the retard side as the target value Vt increases. ΔV is a positive correction amount having a relatively small absolute value.

  When the target value Vt is changed in this way, the valve timing of the exhaust valve of the deactivated cylinder approaches the expansion bottom dead center by a small amount. Then, the exhaust gas amount per suction can be increased, and the actual in-cylinder gas amount and in-cylinder pressure can be increased (that is, made closer to) the target in-cylinder gas amount Gt and the target in-cylinder pressure. If step S106 is repeatedly executed, the valve timing of the exhaust valve of the idle cylinder gradually approaches the expansion bottom dead center. Therefore, the exhaust gas amount per suction can be increased little by little, and the actual in-cylinder gas amount and in-cylinder pressure can be increased earlier toward the target in-cylinder gas amount Gt and the target in-cylinder pressure.

  On the other hand, if the estimated in-cylinder gas amount Ge is equal to or greater than the target in-cylinder gas amount Gt, the process proceeds to step S107, and the target value Vt is changed or corrected to a more advanced value (Vt−ΔV). Then, the valve timing of the exhaust valve of the idle cylinder moves away from the expansion bottom dead center by a small amount. Then, the amount of exhaust gas per suction can be reduced, and the actual in-cylinder gas amount and in-cylinder pressure can be reduced (that is, approached) toward the target in-cylinder gas amount Gt and the target in-cylinder pressure. If step S107 is repeatedly executed, the valve timing of the exhaust valve of the deactivated cylinder gradually moves away from the expansion bottom dead center. Therefore, the amount of exhaust gas per suction can be reduced little by little, and the actual in-cylinder gas amount and in-cylinder pressure can be reduced earlier toward the target in-cylinder gas amount Gt and the target in-cylinder pressure.

  Thus, the variable valve timing mechanism 33 is feedback controlled so that the estimated in-cylinder gas amount Ge approaches the target in-cylinder gas amount Gt.

  By the way, in this embodiment, exhaust passages 11A and 11B are provided independently for each of the idle cylinders (# 1, # 3, # 5 cylinders) and the active cylinders (# 2, # 4, # 6 cylinders). Yes. In this case, if the execution time of the reduced cylinder operation is too long, the exhaust gas existing in the first exhaust passage 11A on the deactivated cylinder side is sucked into the cylinder of the deactivated cylinder and consumed. There is a problem that exhaust emission deteriorates when the reduced-cylinder operation is terminated and all-cylinder operation is started (or resumed or restored).

  During the reduced cylinder operation, the exhaust gas sucked into the cylinder of the idle cylinder leaks into the crankcase through the gap between the piston ring and the cylinder inner wall, and is sent to the intake passage 2 through the blow-by gas circulation passage (not shown). After being sucked into the working cylinder and used for combustion in the working cylinder, it is discharged to the atmosphere through the second exhaust passage 11B on the working cylinder side. Since the second exhaust passage 11B is not joined to the first exhaust passage 11A, the supply of exhaust gas from the second exhaust passage 11B to the first exhaust passage 11A does not occur.

  Further, during the reduced-cylinder operation, the exhaust gas that exists or stays in the first exhaust passage 11A on the idle cylinder side is gradually sucked into the cylinder of the idle cylinder and is eventually consumed. As the exhaust gas is consumed, fresh air flowing in from the outlet end (tail pipe) of the first exhaust passage 11A gradually flows back in the first exhaust passage 11A and eventually fills the first exhaust passage 11A, and is stopped. It will be sucked into the cylinder.

  As a result, the upstream catalyst 15A and the downstream catalyst 16A made of a three-way catalyst having oxygen storage capacity are in a state of storing oxygen up to the vicinity of the upper limit of their own oxygen storage capacity, and NOx is sufficiently absorbed immediately after returning to all-cylinder operation. Unable to purify and exhaust emissions deteriorate. In addition, since fresh air enters the cylinder of the deactivated cylinder, the ratio between the fresh air amount and the residual exhaust gas amount in the cylinder is different from that in all-cylinder operation, specifically compared to that in all-cylinder operation. As a result, the air-fuel ratio of the in-cylinder gas becomes lean. When returning to the all cylinder operation in this state, there is a problem that the fuel injection amount becomes short immediately after the return, the NOx emission amount increases or misfires, or the accuracy of air-fuel ratio control deteriorates.

  Therefore, in this embodiment, during the reduced-cylinder operation, the reduced-cylinder operation is stopped when the amount of exhaust gas sucked into the idle cylinder from the first exhaust passage 11A and consumed from the first exhaust passage 11A exceeds a predetermined amount. , Especially temporarily stop. By doing so, it is possible to suppress the deterioration of exhaust emission accompanying the consumption of exhaust gas in the first exhaust passage 11A.

  The predetermined amount here is an amount such that the amount of exhaust gas consumption becomes so significant that the exhaust emission deteriorates. For example, if fresh air flows backward with exhaust gas consumption and fills the downstream catalyst 16A, it becomes difficult to purify NOx by the downstream catalyst 16A immediately after returning to the all-cylinder operation. Therefore, the amount of exhaust gas consumed such that fresh air fills the downstream catalyst 16A can be set to a predetermined amount. Alternatively, if exhaust gas is further consumed and fresh air also fills the upstream catalyst 15A, it becomes difficult to purify NOx by the upstream catalyst 15A immediately after returning to the all-cylinder operation. Therefore, the amount of exhaust gas consumed such that fresh air also fills the upstream catalyst 15A can be set to a predetermined amount. Alternatively, if exhaust gas is further consumed and fresh air flows into the cylinder, problems such as an increase in NOx emission, misfire or deterioration in air-fuel ratio control accuracy occur immediately after returning to the all-cylinder operation. Therefore, the consumption amount of exhaust gas that allows fresh air to flow into the cylinder can be set to a predetermined amount.

  When the exhaust gas consumption exceeds a predetermined amount, the reduced-cylinder operation can be stopped not temporarily but continuously. However, this inevitably loses the opportunity to perform the reduced-cylinder operation, and makes it difficult to obtain the original effect of improving the fuel consumption due to the reduced-cylinder operation. Further, the execution time of the all cylinder operation after stopping the reduced cylinder operation may be a time such that the exhaust gas fills the downstream catalyst 16A, for example, and it is considered that a long time is not required. Therefore, in this embodiment, the reduced-cylinder operation is temporarily stopped.

  The reduced-cylinder operation is executed only when a predetermined condition is satisfied, for example, when the vehicle is cruising at high speed and the engine is operating steadily. Even if the condition is satisfied, the reduced-cylinder operation is forcibly suspended when the execution time of the reduced-cylinder operation exceeds a predetermined time.

  FIG. 14 shows a flowchart relating to a routine for temporarily stopping the reduced-cylinder operation. The routine is repeatedly executed by the ECU 100 at every predetermined calculation cycle τ.

  In step S201, it is determined whether or not a flag to be turned on / off in a later-described step is on. If it is on, the process proceeds to step S209. If it is off, the process proceeds to step S202.

  In step S202, it is determined whether or not the reduced cylinder operation is being performed. If the reduced-cylinder operation is not being performed, the current process is terminated. If the reduced-cylinder operation is being performed, the process proceeds to step S203. In step S203, the actual engine speed Ne and load KL are acquired.

  In step S204, the exhaust gas amount actually consumed from the first exhaust passage 11A, that is, the exhaust gas consumption amount Gb is calculated or estimated from a predetermined map based on the acquired value of the rotational speed Ne and the load KL. . The exhaust gas consumption amount Gb here is an amount consumed during one calculation cycle τ. In step S205, the exhaust gas consumption amount Gb is integrated. This integrated value is represented by ΣGb. The exhaust gas consumption integrated value ΣGb is the total amount of exhaust gas estimated to have been consumed from the start of the reduced cylinder operation until the present time.

  In step S206, the exhaust gas consumption integrated value ΣGb is compared with a predetermined threshold value α. The threshold value α is a value corresponding to the predetermined amount. When the exhaust gas consumption integrated value ΣGb is equal to or less than the threshold value α, the current process is terminated.

  On the other hand, if the exhaust gas consumption integrated value ΣGb is larger than the threshold value, the process proceeds to step S207, and the reduced-cylinder operation is stopped. Note that all-cylinder operation is executed or resumed at the same time as the reduced cylinder operation is stopped. In this step, the exhaust gas consumption integrated value ΣGb is reset to zero. Next, in step S208, the flag is turned on.

  In step S209, it is determined whether or not the stop time Tb measured from when the reduced-cylinder operation is stopped exceeds a predetermined time β. The predetermined time β can be arbitrarily determined. For example, the time when the downstream catalyst 16A is filled with exhaust gas or the entire first exhaust passage 11A is filled with exhaust gas by performing all cylinder operation. Set to time. The specific time is about 5 seconds, for example. If the stop time Tb does not exceed the predetermined time β, the current process is terminated.

  On the other hand, when the stop time Tb exceeds the predetermined time β, the process proceeds to step S210, and the reduced-cylinder operation is executed or restarted. As a result, the reduced-cylinder operation is temporarily stopped. All cylinder operation is stopped simultaneously with the resumption of the reduced cylinder operation. In this step, the stop time Tb is reset to zero.

  Finally, in step S211, the flag is turned off.

  According to the above routine, since the flag is off when the first routine is executed, the process proceeds to step S202, and if the reduced-cylinder operation is being performed (step S202: YES), the exhaust gas consumption integrated value ΣGb is calculated in steps S203 to S205. The When the reduced-cylinder operation is executed (as the execution time of the reduced-cylinder operation becomes longer), the exhaust gas consumption integrated value ΣGb gradually increases and the exhaust gas consumption integrated value ΣGb exceeds the threshold value α ( In step S206: Yes), the reduced-cylinder operation is stopped (step S207), and the flag is turned on (step S208). Then, when the next routine is executed, the process moves from step S201 to step S209, and the stop time Tb is compared with the predetermined time β while the reduced-cylinder operation stop state is maintained. If the stop time Tb exceeds the predetermined time β (step S209: YES), the reduced-cylinder operation is restarted (step S210), and the flag is turned off (step S211).

  All-cylinder operation is executed while the reduced-cylinder operation is temporarily stopped, and the exhaust gas can flow into the first exhaust passage 11A. Therefore, after that, even when the reduced-cylinder operation is resumed, the exhaust gas can be sucked and replenished into the cylinder of the deactivated cylinder, and the deterioration of the exhaust emission as described above can be suppressed.

  Further, since the exhaust gas consumption Gb is a value that changes in accordance with the engine operating state (particularly, the rotational speed and the load), the engine operation is determined by determining whether or not to stop the reduced-cylinder operation based on the integrated value ΣGb. The determination can be made in consideration of the state history, and the reduced-cylinder operation can be stopped at an appropriate timing.

  Thus, the ECU 100 constituting the cylinder control unit stops the reduced cylinder operation when the amount of exhaust gas (ΣGb) consumed from the first exhaust passage 11A exceeds the predetermined amount (α) during the reduced cylinder operation. Is.

  Alternatively, the new air amount in the first exhaust passage 11A is estimated by subtracting the exhaust gas consumption integrated value ΣGb from the volume of the first exhaust passage 11A (which is a predetermined fixed value that is physically determined). When the air volume exceeds a predetermined fresh air volume, the reduced-cylinder operation may be stopped. Such a case is also included when the amount of exhaust gas consumed from the first exhaust passage 11A exceeds a predetermined amount.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. Note that a description of the same parts as those in the first embodiment is basically omitted. In general, the second embodiment is different from the first embodiment in that the exhaust stroke is performed at the timing when the exhaust valve of the idle cylinder is slightly lifted during the reduced-cylinder operation.

  FIG. 15 shows a valve lift diagram of the second embodiment. In particular, attention should be paid to a line L5 indicating a valve lift diagram of the exhaust valve of the idle cylinder during the reduced cylinder operation.

  At this time as well, the exhaust valve opens with a smaller lift amount and operating angle than when all cylinders are operating (that is, the valve is slightly lifted), but the exhaust valve is opened only substantially during the exhaust stroke (particularly in the previous period). To do. In other words, the profile of the base circle portion 45 (including the cam nose portion 55A) is formed so that such a state is realized. The cam nose portion 55A of the present embodiment is shown in phantom lines in FIGS.

  As in the first embodiment, the valve timing of the exhaust valve can be arbitrarily changed within the range from the line L5 'to the line L5 by the action of the variable valve timing mechanism 33. In particular, the opening period of the exhaust valve can be changed in the direction of approaching or leaving the expansion bottom dead center within the range of the exhaust stroke. In the illustrated example, the exhaust valve opens before the expansion bottom dead center when it is at the most advanced angle position (L5 ′), but the valve opening period before the expansion bottom dead center is negligible. Can do. Opening the exhaust valve only in the exhaust stroke is synonymous with opening the exhaust valve substantially only in the exhaust stroke.

  In FIG. 15, the other lines L1 (L1 '), L3 (L3'), and L4 are the same as those in FIG.

  Also in the present embodiment, in the exhaust stroke (particularly in the previous period), the pressure in the cylinder is lower than that of the first exhaust passage 11A. Therefore, the exhaust gas is first exhausted by slightly lifting the exhaust valve as described above. It can be sucked into the cylinder from the passage 11A and continuously replenished. As a result, the cylinder pressure and cylinder gas amount of the idle cylinder can be maintained at optimum desired values.

  Also in this embodiment, the in-cylinder gas amount and the in-cylinder pressure increase as the valve opening period of the exhaust valve approaches the expansion bottom dead center, and the in-cylinder gas amount and the cylinder pressure increase as the valve opening period of the exhaust valve increases from the expansion bottom dead center. In-cylinder pressure tends to decrease.

  The cylinder pressure control routine for the idle cylinder shown in FIG. 13 is modified as follows. That is, the target value Vt is corrected to a more advanced value (Vt−ΔV) in step S106, and the target value Vt is corrected to a more retarded value (Vt + ΔV) in step S107. There is no change in the reduced cylinder operation stop routine shown in FIG.

  The preferred embodiment of the present invention has been described in detail above, but various other embodiments of the present invention are conceivable. For example, the following other embodiments are possible.

  (1) In the above embodiment, during the reduced cylinder operation, both the lift amount and the operating angle of the exhaust valve of the idle cylinder are set to be smaller than those during the operation of all cylinders. Either one of the amount and the working angle may be set to a state smaller than that during all-cylinder operation. In this case, it will be apparent to those skilled in the art that the first exhaust-side variable valve mechanism 32A can be modified to do so.

  (2) During the reduced-cylinder operation, the exhaust valve is opened only in the expansion stroke in the first embodiment and only in the exhaust stroke in the second embodiment. Instead, the exhaust valve is exhausted in both the expansion stroke and the exhaust stroke. The valve may be opened. It will be apparent to those skilled in the art that in this case as well, the first exhaust-side variable valve mechanism 32A can be modified to do so. In this case, regarding the in-cylinder pressure control, the variable valve timing mechanism 33 allows the exhaust valve opening period to be changed over both the expansion stroke and the exhaust stroke, and the exhaust valve opening period is set to increase the in-cylinder pressure. It is conceivable to approach the inflated bottom dead center.

  During the reduced-cylinder operation, the exhaust valve of the idle cylinder may be opened in at least one of the intake stroke and the compression stroke. Even during these strokes, if the in-cylinder pressure is lower than the internal pressure of the first exhaust passage 11A while the exhaust valve is open (especially near the intake bottom dead center, late in the intake stroke or early in the compression stroke), the exhaust gas is discharged. This is because it can be inhaled into the cylinder.

  (3) The first exhaust-side variable valve mechanism 32A is not limited to the one provided with the cam unit 42 as described above, and an arbitrary one can be applied. For example, a variable valve mechanism including an electromagnetic drive actuator or a hydraulic drive actuator that can change the operating characteristics of the exhaust valve relatively freely can be applied.

  (4) The variable valve mechanisms 31B and 32B on the operating cylinder side can be omitted. Further, the variable valve timing mechanism 33 can be omitted in all the variable valve mechanisms 31A, 32A, 31B, and 32B.

  (5) The type of the internal combustion engine is not limited to the V type, and may be any, for example, a series type or a horizontally opposed type. The number of cylinders of the internal combustion engine is not limited to six as long as it is plural, and may be any number, for example, 2, 3, 4, 5, 8, 10, 12.

  The embodiment of the present invention is not limited to the above-described embodiment, and includes all modifications, applications, and equivalents included in the concept of the present invention defined by the claims. Therefore, the present invention should not be construed as being limited, and can be applied to any other technique belonging to the scope of the idea of the present invention.

1 Internal combustion engine
11A First exhaust passage 11B Second exhaust passage 25 Exhaust valve 30A First variable valve mechanism 30B Second variable valve mechanism 31A First intake side variable valve mechanism 32A First exhaust side variable valve Mechanism 31B Second intake side variable valve mechanism 32B Second exhaust side variable valve mechanism 33 Valve timing variable mechanism 40 Valve lift variable mechanism 100 Electronic control unit (ECU)

Claims (1)

The first exhaust passage and the second exhaust passage provided independently for each of some of the cylinders and the remaining cylinder, and the operating characteristics of the intake valves and exhaust valves of at least some of the cylinders. A variable cylinder control device for an internal combustion engine comprising a variable valve mechanism for making it variable,
A cylinder controller configured to perform one of an all-cylinder operation in which all the cylinders are operated during the operation of the internal combustion engine and a reduced cylinder operation in which the remaining cylinders are deactivated and the remaining cylinders are operated; ,
A valve control unit configured to control the variable valve mechanism;
With
The valve control unit maintains the intake valves of the some cylinders in a closed state during the reduced-cylinder operation, and sets the exhaust valves of the some cylinders so that at least one of the lift amount and the operating angle is all cylinders. Controlling the variable valve mechanism so that the valve is opened so that the exhaust gas in the first exhaust passage becomes less than during operation and is sucked into the some cylinders;
The variable cylinder control device for an internal combustion engine, wherein the cylinder control unit stops the cylinder reduction operation when the amount of exhaust gas consumed from the first exhaust passage exceeds a predetermined amount during the cylinder reduction operation. .

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