JP2018159339A - Control device of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of an engine capable of securing performance of a hydraulic valve stopping mechanism regardless of an operational state.SOLUTION: A control device of an engine has a valve stopping mechanism 14b capable of closing intake valves and exhaust valves of first and fourth cylinders among four cylinders on the basis of establishment of cylinder reduction operation execution conditions, an ECU 110 controlling the valve stopping mechanism 14b, an oil temperature sensor 100, an oil level sensor 101, and a turning acceleration sensor 103. The ECU 110 determines an operation state in which mixing of air to an oil supplied to the valve stopping mechanism 14b is assumed, when an oil level is a determination value D or less, a turning acceleration of a vehicle is a determination value G or more, or an oil temperature is a determination temperature T1b or more, and prohibits switching of an operation even when a switching execution condition from a full-cylinder operation to a cylinder reduction operation is established.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an engine control device, and more particularly to an engine control device capable of executing a reduced-cylinder operation in which operation of some cylinders among a plurality of cylinders is stopped.

Conventionally, a plurality of cylinders and a deactivated cylinder (for example, first to first cylinders) are set from a plurality of cylinders when a condition for executing a reduced-cylinder operation that deactivates some of the plurality of cylinders is established. 2. Description of the Related Art There is known an engine control device that includes a valve stop mechanism that closes intake and exhaust valves of first and fourth cylinders of four cylinders, and a control unit that controls the valve stop mechanism.
The engine control device of Patent Document 1 has a hydraulic valve stop mechanism that closes intake and exhaust valves of a plurality of deactivated cylinders when a condition for executing reduced-cylinder operation is satisfied, and at low load, low engine speed, or low vehicle speed. At this time, the reduced-cylinder operation is prohibited, and the exhaust valve of the deactivated cylinder is opened before the intake valve when the switching execution condition from the reduced-cylinder operation to the all-cylinder operation is satisfied.

In reduced-cylinder operation, the engine output decreases due to a decrease in the number of cylinders and torque shock occurs, so when the reduced-cylinder operation execution condition is satisfied, the throttle valve opening is reduced before stopping combustion in some cylinders. After increasing and increasing the amount of air sucked in all the cylinders, combustion of some cylinders is stopped.
As a result, the amount of air supplied to all four cylinders increases as a result of increasing the amount of air in a stage before the combustion of the cylinders to be stopped is stopped, that is, the so-called switching transition period. There was a possibility that the output of the entire engine before the start would increase and cause a torque shock.

  The engine control device disclosed in Patent Document 2 sets a deactivated cylinder from a plurality of cylinders and closes intake / exhaust valves of the deactivated cylinders when a reduced cylinder operation execution condition is established that deactivates some of the cylinders. A hydraulic valve stop mechanism that controls the hydraulic valve and a control unit that controls the hydraulic valve stop mechanism, and the control unit reduces the amount of air sucked into each cylinder when the reduced cylinder operation execution condition is satisfied. Preparation control to increase the opening of the throttle valve and change the ignition timing of the ignition means to the retard side timing so that the amount of air is larger than the amount of air during normal all-cylinder operation where the execution condition is not satisfied After the completion of the preparation control, the intake / exhaust valve of the cylinder to be deactivated is closed and the ignition means is stopped.

Japanese Patent No. 5563867 Japanese Patent Laid-Open No. 2006-050510

Since the engine control apparatus of Patent Literatures 1 and 2 constitutes a valve stop mechanism using an existing oil pump and oil supply circuit, production cost can be reduced and the size can be reduced.
On the other hand, since the hydraulic valve stop mechanism uses oil (hydraulic oil) as a drive power medium, the response and follow-up of the hydraulic valve stop mechanism may be reduced depending on the state of the oil.
In the engine control device disclosed in Patent Document 1, when the oil temperature is lower than 40 ° C., the fluidity of the oil is lowered. Therefore, the valve stop mechanism is deactivated and switching from the all-cylinder operation to the reduced-cylinder operation is prohibited. ing.

However, even in a situation where the oil itself can ensure sufficient fluidity due to its physical properties, the responsiveness and followability of the hydraulic valve stop mechanism may be reduced depending on the driving state of the vehicle.
For example, when the oil level stored in the oil pan is lowered, air is sucked from the oil strainer. In addition, when the vehicle turns sharply, the oil stored in the oil pan is agitated with air, so that bubbles that are compressed fluid (hereinafter referred to as air) are mixed into the oil that is non-compressed fluid.
Therefore, sufficient oil pressure cannot be applied to the pressure receiving portion, and the switching time from the all-cylinder operation to the reduced-cylinder operation or the switching time from the reduced-cylinder operation to the all-cylinder operation (switching transition period) is prolonged. .

  In particular, as in the engine control device of Patent Document 2, in order to make the required torque constant when switching the reduced cylinder operation, the opening of the throttle valve is increased and the ignition timing of the ignition means is changed to the retard side timing. When the preparation control is adopted, the ignition timing retarding control time becomes longer as the switching time becomes longer, resulting in a deterioration in fuel consumption and, as a result, a sufficient fuel consumption improvement effect by reduced-cylinder operation is obtained. There is a possibility that it cannot be done.

  An object of the present invention is to provide an engine control device or the like that can ensure the performance of a hydraulic valve stop mechanism regardless of the operating state.

  The engine control apparatus according to claim 1 sets a deactivated cylinder from the plurality of cylinders when a plurality of cylinders and an execution condition of a reduced cylinder operation that deactivates some of the plurality of cylinders are established. In an engine control apparatus comprising a hydraulic valve stop mechanism that closes an intake valve and an exhaust valve of a deactivated cylinder, and a control means that controls the hydraulic valve stop mechanism, the control means includes the hydraulic valve stop mechanism. When air is assumed to be mixed in the oil supplied to the mechanism, the operation switching is limited even if the switching execution condition from the all-cylinder operation to the reduced cylinder operation is satisfied.

In this engine control device, when the control means is assumed to be mixed with air in the oil supplied to the hydraulic valve stop mechanism, the operation is performed even if the condition for executing the switching from the all-cylinder operation to the reduced-cylinder operation is satisfied. Since the switching is restricted, the switching operation in a state where air, which is a compressed fluid, is mixed in the oil can be restricted, and the operation switching time can be prevented from being prolonged.
That is, the responsiveness and followability of the hydraulic valve stop mechanism can be maintained regardless of the driving state, and the operability of the vehicle can be improved.

The invention of claim 2 comprises the oil level detection means capable of detecting the oil level of an oil pan for storing oil supplied to the hydraulic valve stop mechanism in the invention of claim 1, wherein the control means comprises: When the oil level detected by the oil level detection means is equal to or lower than a determination value, it is determined that the operating state is assumed to be mixed with air in the oil supplied to the hydraulic valve stop mechanism.
According to this configuration, the oil level can be determined as a parameter for the operation state in which air is assumed to be mixed in the oil. That is, it is possible to determine a state in which air is sucked from the oil strainer and the amount of air in the oil increases according to the oil level.

According to a third aspect of the invention, there is provided a turning acceleration detecting means capable of detecting a turning acceleration of the vehicle according to the first aspect of the invention, and the control means has a turning acceleration detected by the turning acceleration detecting means equal to or greater than a determination value. In this case, it is determined that the operating state in which air is assumed to be mixed in the oil supplied to the hydraulic valve stop mechanism is characterized.
According to this configuration, the turning acceleration can be determined as a parameter for the operating state in which air is assumed to be mixed in the oil. That is, it is possible to determine the state in which the oil stored in the oil pan is agitated with the air based on the turning acceleration.

According to a fourth aspect of the present invention, in the second or third aspect of the invention, there is provided an oil temperature detecting means capable of detecting an oil temperature supplied to the hydraulic valve stop mechanism, and the control means includes the oil temperature detecting means. When the oil temperature detected by the above is larger than a determination value, it is determined that the operating state in which air is assumed to be mixed in the oil supplied to the hydraulic valve stop mechanism is characterized.
According to this configuration, the oil temperature can be determined as a parameter for the operating state in which air is assumed to be mixed in the oil. That is, it is possible to determine a state in which the viscosity of the oil is lowered and air is easily introduced into the oil depending on the oil temperature.

According to a fifth aspect of the invention, in the invention according to any one of the first to fourth aspects, the control means determines that the oil supplied to the hydraulic valve stop mechanism is in an operating state in which air is expected to be mixed. The operation switching to the reduced-cylinder operation is prohibited.
According to this configuration, the operation switching operation in a state where air is mixed in the oil can be prohibited, and the operation switching time can be reliably prevented from being prolonged.

According to a sixth aspect of the present invention, in the invention according to any one of the first to fourth aspects, when the engine operating state is a reduced-cylinder operating region defined by the engine speed and the target indicated torque, When it is determined that the condition for executing the switching from the cylinder operation to the reduced cylinder operation is satisfied, and when it is determined that the air supplied to the oil supplied to the hydraulic valve stop mechanism is in an operating state, the reduction cylinder operation region It is characterized by lowering the upper limit of the engine speed.
According to this configuration, since the operation switching operation in the high-speed operation region where air is likely to be mixed into the oil is limited, it is possible to achieve both improvement in fuel efficiency and performance securing of the hydraulic valve stop mechanism.

  According to the engine control apparatus of the present invention, the performance of the hydraulic valve stop mechanism can be ensured regardless of the operating state.

1 is a schematic plan view showing an overall configuration of an engine according to Embodiment 1. FIG. It is a longitudinal cross-sectional view of an engine. It is a figure which shows a valve stop mechanism, Comprising: (a) A pivot part is a locked state, (b) is a state before a pivot part transfers to a lock release state, (c) A pivot part shows a lock release state ing. It is the schematic which shows the structure of an oil supply apparatus. It is a block diagram which shows the control system of an engine. It is the map which set the all cylinder operation area | region and the reduced cylinder operation area | region. It is explanatory drawing of the calculation method of an air filling rate. It is a flowchart which shows the operating condition determination processing content. It is a flowchart which shows the control processing content by the control apparatus of an engine. It is a time chart which shows the time change of each parameter. 10 is a flowchart showing the operation condition determination processing content according to the second embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
The following description is an example in which the present invention is applied to an engine control device, and does not limit the present invention, its application, or its use.

  Embodiment 1 of the present invention will be described below with reference to FIGS.

(Entire engine configuration)
As shown in FIGS. 1 and 2, the engine 1 is, for example, an in-line four-cylinder gasoline engine in which a first cylinder to a fourth cylinder are sequentially arranged in series, and is mounted on a vehicle such as an automobile.
In the engine 1, a head cover 2, a cylinder head 3, a cylinder block 4, a crankcase (not shown), and an oil pan 5 (see FIG. 4) are connected to each other vertically.
A piston 6 slidable in four cylinder bores 9 formed in each cylinder block 4 and a crankshaft 7 rotatably supported by a crankcase are connected by a connecting rod 8. Combustion chambers 11 are formed in each cylinder by the cylinder bore 9, piston 6, and cylinder head 3 of the cylinder block 4.
Each combustion chamber 11 is provided with an injector 12 and a spark plug 13, and ignition is performed in the order of the first cylinder → the third cylinder → the fourth cylinder → the second cylinder.

  The intake system of the engine 1 includes an intake port 21 that communicates with the combustion chamber 11, an independent intake passage 22 that communicates with each of the intake ports 21, a surge tank 23 that is connected in common to the independent intake passage 22, The intake pipe 24 extends from the surge tank 23 to the upstream side. A butterfly throttle valve 25 capable of adjusting the amount of air introduced into the engine 1 via an air duct (not shown) is provided in the middle of the intake pipe 24, and the throttle valve 25 is driven in the vicinity thereof. An actuator 26 (electric motor) is installed. Further, the exhaust system of the engine 1 includes an exhaust port 31 that communicates with the combustion chamber 11, an independent exhaust passage 32 that communicates with each of the exhaust ports 31, a collective portion 33 in which the independent exhaust passages 32 gather, The exhaust pipe 34 extends downstream from the portion 33. A butterfly type exhaust shutter valve 35 capable of adjusting the amount of exhaust gas discharged from the engine 1 is provided in the middle of the exhaust pipe 34, and an actuator 36 (for driving the exhaust shutter valve 35) is provided in the vicinity thereof. Electric motor) is installed.

As shown in FIG. 2, the intake port 21 and the exhaust port 31 are provided with an intake valve 41 and an exhaust valve 51 for opening and closing each. The intake valve 41 and the exhaust valve 51 are urged in the valve closing direction (upward) by return springs 42 and 52, respectively, and swing by cam portions 43a and 53a provided on the outer periphery of the rotating cam shafts 43 and 53, respectively. Cam followers 44a and 54a, which are rotatably provided at substantially central portions of the arms 44 and 54, are pressed downward.
The swing arms 44 and 54 swing around the tops of the pivot mechanisms 14a and 15a provided on one end sides of the swing arms 44 and 54, respectively, so that the intake valve 41 and the exhaust valve 51 are provided at the other ends of the swing arms 44 and 54, respectively. Is opened downward by being pushed downward against the urging force of the return springs 42 and 52.

  As the pivot mechanism 15a in the swing arms 44 and 54 of the second and third cylinders formed in the center of the engine 1 in the cylinder arrangement direction, the valve clearance is set by oil pressure (hereinafter simply referred to as oil pressure). A known hydraulic lash adjuster (hereinafter abbreviated as HLA) 15 that automatically adjusts to zero is provided. The pivot mechanism 15a has the same configuration as a pivot mechanism 14a of the HLA 14 described later.

As shown in FIG. 2, HLA 14 with a valve stop mechanism having a pivot mechanism 14a is provided for swing arms 44 and 54 of the first and fourth cylinders formed at both ends of the engine 1 in the cylinder arrangement direction. Yes. The HLA 14 with a valve stop mechanism is configured so that the valve clearance can be automatically adjusted to zero by hydraulic pressure, similarly to the HLA 15.
Further, the HLA 14 stops the opening / closing operation of the intake and exhaust valves 41 and 51 of the first and fourth cylinders during the reduced cylinder operation in which the operations of the first and fourth cylinders, which are a part of all four cylinders of the engine 1, are stopped. When all cylinders are operated to operate all four cylinders, the intake and exhaust valves 41 and 51 of the first and fourth cylinders are opened and closed. The intake and exhaust valves 41 and 51 of the second and third cylinders operate in both the reduced cylinder operation and the all cylinder operation.
Therefore, during the reduced cylinder operation, the intake and exhaust valves 41 and 51 of the first and fourth cylinders of the first to fourth cylinders of the engine 1 stop operating, and during the all cylinder operation, the first to fourth cylinders The intake / exhaust valves 41 and 51 are operating. Note that the reduced-cylinder operation and the all-cylinder operation are appropriately switched according to the operating state of the engine 1 as described later.

Mounting holes 45 and 55 for inserting and mounting the lower end portion of the HLA 14 are provided in the intake side and exhaust side portions respectively corresponding to the first and fourth cylinders of the cylinder head 3. Further, in order to insert and mount the lower end portion of the HLA 15 in the intake side and exhaust side portions respectively corresponding to the second and third cylinders, mounting holes (not shown) similar to the mounting holes 45 and 55 are provided, respectively. It has been.
A pair of oil passages 71 and 73 are formed in the mounting hole 45, and a pair of oil passages 72 and 74 are formed in the mounting hole 55. The oil passages 71 and 72 are configured to supply hydraulic pressure for operating the valve stop mechanism 14b of the HLA 14, and the oil passages 73 and 74 are configured to supply hydraulic pressure for operating the pivot mechanism 14a of the HLA 14. Only the oil passages 73 and 74 are communicated with the mounting holes of the HLA 15.

  As shown in FIG. 3A, the valve stop mechanism 14b is provided with a lock mechanism 140 that locks the operation of the pivot mechanism 14a. The lock mechanism 140 can advance and retreat with respect to the through-holes 141a formed at two locations opposed to each other in the radial direction on the side peripheral surface of the bottomed outer cylinder 141 that houses the pivot mechanism 14a slidably in the axial direction. A pair of lock pins 142 formed in the above are provided. The pair of lock pins 142 is biased radially outward by a spring 143. Between the inner bottom portion of the outer cylinder 141 and the bottom portion of the pivot mechanism 14a, a lost motion spring 144 that presses and urges the pivot mechanism 14a above the outer cylinder 141 is disposed.

When both lock pins 142 are fitted in the through holes 141a of the outer cylinder 141, the pivot mechanism 14a located above the lock pins 142 is fixed in a state of protruding upward.
As a result, the top of the pivot mechanism 14a serves as a fulcrum for the swing of the swing arms 44 and 54. Therefore, when the cam portions 43a and 53a push the cam followers 44a and 54a downward by the rotation of the cam shafts 43 and 53, intake and exhaust are performed. The valves 41 and 51 are pushed downward against the urging force of the return springs 42 and 52 to open. That is, the all-cylinder operation is executed by setting both the lock pins 142 in the through holes 141a.

As shown in FIGS. 3B and 3C, when the outer ends of both lock pins 142 are pressed by the hydraulic pressure indicated by the black arrows, both lock pins 142 are resisted against the urging force of the spring 143. The outer cylinder 141 moves backward in the radial direction so as to approach.
As a result, both lock pins 142 come out of the through hole 141a, and the pivot mechanism 14a located above the lock pin 142 moves together with the lock pin 142 to the lower side in the axial direction of the outer cylinder 141 to be in a valve stop state.
The biasing force of the return springs 42 and 52 is set to be stronger than the biasing force of the lost motion spring 144. Therefore, when the cam portions 43a, 53a push the cam followers 44a, 54a downward by the rotation of the cam shafts 43, 53, the top portions of the intake / exhaust valves 41, 51 become fulcrums for swinging of the swing arms 44, 54. The pivot mechanism 14a is pushed downward against the urging force of the lost motion spring 144 while the intake and exhaust valves 41 and 51 are kept closed. That is, the reduced-cylinder operation is executed by setting both the lock pins 142 to the through holes 141a.

(Oil supply circuit)
As shown in FIG. 4, the oil supply circuit includes a variable displacement oil pump 16 driven by rotation of the crankshaft 7, and oil that has been boosted by being connected to the oil pump 16. And an oil supply passage 60 that leads to the hydraulic actuator.
The oil supply passage 60 is an oil passage formed in the cylinder head 3 and the cylinder block 4 or the like. The oil supply passage 60 includes first to third communication passages 61 to 63, a main gallery 64, a plurality of oil passages 71 to 79, and the like.

The first communication path 61 communicates with the oil pump 16 and extends from the discharge port 16 b of the oil pump 16 to the branch point 64 a in the cylinder block 4.
The main gallery 64 extends in the cylinder row direction within the cylinder block 4.
The second communication path 62 extends from a branch point 64 b on the main gallery 64 to a branch part 63 b on the cylinder head 3. The third communication path 63 extends in the horizontal direction between the intake side and the exhaust side in the cylinder head 3. The plurality of oil passages 71 to 79 branch from the third communication passage 63 in the cylinder head 3.

The oil pump 16 is a known variable capacity oil pump that changes the capacity of the oil pump 16 to vary the oil discharge amount of the oil pump 16, and includes a housing, a drive shaft, a pump element, a cam ring, And a spring and a ring member.
The housing has a suction port 16 a for supplying oil to the internal pump chamber 161 and a discharge port 16 b for discharging oil from the pump chamber 161.
A pressure chamber 162 defined by the inner peripheral surface of the housing and the outer peripheral surface of the cam ring is formed inside the housing, and an introduction hole 16c is provided in the pressure chamber 162.

An oil strainer 18 facing the oil pan 5 is provided at the suction port 16 a of the oil pump 16. An oil filter 65 and an oil cooler 66 are arranged in order from the upstream side to the downstream side in the first communication path 61 communicating with the discharge port 16b of the oil pump 16.
The oil stored in the oil pan 5 is pumped up by the oil pump 16 through the oil strainer 18, then filtered by the oil filter 65, cooled by the oil cooler 66, and then the main gallery in the cylinder block 4. 64.
The oil pan 5 is provided with an oil level sensor 101 (see FIG. 5) that detects an oil level (oil amount) stored in the oil pan 5.

The main gallery 64 rotatably connects a metal bearing oil supply portion 81 disposed on five main journals that rotatably support the crankshaft 7 and four connecting rods 8, and a crankpin of the crankshaft 7. Is connected to an oil supply part 82 of a metal bearing arranged in Oil is constantly supplied to the main gallery 64.
On the downstream side of the branch point 64 c of the main gallery 64, an oil supply unit 83 that supplies oil to a hydraulic chain tensioner (not shown) of the timing chain, and oil that supplies oil to the pressure chamber 162 of the oil pump 16. The path 70 is connected. The oil passage 70 communicates from the branch point 64 c of the main gallery 64 to the introduction hole 16 c of the oil pump 16, and a linear solenoid valve 89 capable of electrically controlling the oil flow rate is provided in the middle of the oil passage 70.

  The oil passage 78 branched from the branch point 63 a of the third communication passage 63 is connected to the exhaust side first direction switching valve 84, and the advance side oil passage 201 is controlled by the exhaust side first direction switching valve 84. The oil is supplied to the advance working chamber 203 and the retard working chamber 204 of the exhaust VVT 20 to be described later via the retard angle oil passage 202. Further, the oil passage 74 branched from the branch point 63a is connected to the oil supply unit (see the white triangle Δ in FIG. 4), the HLA 15, the HLA 14, the fuel pump 87, and the vacuum pump 88. . The oil passage 76 that branches from the branch point 74 a of the oil passage 74 is connected to an oil shower that supplies lubricating oil to the exhaust-side swing arm 54, and oil is also constantly supplied to the oil passage 76.

  A hydraulic pressure sensor 90 that detects the hydraulic pressure of the oil passage 77 is disposed in the oil passage 77 that branches from the branch point 63 c of the third communication passage 63. The oil passage 73 branched from the branch point 63d is connected to the cam journal oil supply portion (see the white triangle Δ in FIG. 4), the HLA 15 and the HLA 14 in the cam shaft 43 on the intake side. . The oil passage 75 that branches from the branch point 73 a of the oil passage 73 is connected to an oil shower that supplies lubricating oil to the swing arm 44 on the intake side.

  The oil passage 79 that branches from the branch point 63c of the third communication passage 63 is provided with a check valve that restricts the direction in which the oil flows in only one direction from the upstream side to the downstream side. This oil passage 79 branches at the branch point 79a on the downstream side of the check valve into the two oil passages 71, 72 communicating with the mounting holes 45, 55 for the HLA 14 with a valve stop mechanism. The oil passages 71 and 72 stop the valve of the HLA 14 with each valve stop mechanism on the intake side and the exhaust side via the intake side second direction switching valve 86 and the exhaust side second direction switching valve 85 as the second hydraulic control valves. Each is connected to the mechanism 14b. By controlling each of the intake side second direction switching valve 86 and the exhaust side second direction switching valve 85, oil is supplied to each valve stop mechanism 14b.

(Phase control mechanism)
In the engine 1, when the reduced cylinder operation is switched, a variable valve timing mechanism (hereinafter abbreviated as VVT) is used to set the opening and closing timings of the intake and exhaust valves 41 and 51 to the retarded side, thereby increasing the combustion gas. The torque is increased and the pumping loss is reduced.
The cam pulleys of the intake VVT 19 and the exhaust VVT 20 are driven by a crankshaft sprocket (not shown) through a timing chain.
As shown in FIG. 4, the intake VVT 19 includes an electric motor 191 and a conversion unit (not shown) formed at one end of the cam shaft 43.
The electric motor 191 is integrally formed with a gear pulley that meshes with the timing chain and rotates synchronously with the crankshaft 7, and the conversion portion is integrally formed with the camshaft 43.
The phase between the gear pulley (timing chain) and the cam shaft 43 is changed by relatively displacing the conversion unit around the axis with respect to the electric motor 191.

The exhaust VVT 20 has an annular housing and a vane body accommodated in the housing (both not shown). The housing is coupled to a cam pulley that rotates in synchronization with the crankshaft 7 so as to be integrally rotatable, and rotates in conjunction with the crankshaft 7. The vane body is connected to a camshaft 53 that opens and closes the exhaust valve 51 by a fastening bolt so as to be integrally rotatable.
A plurality of advance working chambers 203 and retard working chambers 204 are formed in the housing, which are partitioned by an inner peripheral surface of the housing and a plurality of vanes provided on the outer peripheral surface of the vane body. As shown in FIG. 4, the advance working chamber 203 and the retard working chamber 204 are connected to the exhaust side first direction switching valve 84 via an advance side oil passage 201 and a retard side oil passage 202, respectively. Yes. The exhaust side first direction switching valve 84 is connected to the variable displacement oil pump 16. A part of the advance side oil passage 201 and the retard side oil passage 202 are formed in the cam shaft 53 and the vane body, respectively.

As shown in FIG. 4, the VVT 20 is provided with a lock mechanism that locks the operation of the VVT 20. The lock mechanism has a lock pin 205 for fixing the phase angle of the camshaft 53 with respect to the crankshaft 7 at a specific phase.
Each vane is rotated to an advanced position with respect to the cam pulley (crankshaft 7) by the oil supplied through the advance side passage 201, and each vane with respect to the cam pulley is supplied with the oil supplied through the retard side passage 202. Is rotated to the retarded position.
Then, the lock pin 205 urged by the urging spring is fitted into a fitting recess formed in a portion of the vane body where the vane is not formed, thereby being locked.
As a result, the vane body is fixed to the housing, and the phase of the camshaft 53 relative to the crankshaft 7 is fixed.

With the above configuration, the amount of oil supplied to the advance working chamber 203 and the retard working chamber 204 of the VVT 20 can be controlled by controlling the exhaust-side first direction switching valve 84. Specifically, when oil is supplied to the advance working chamber 203 with a larger supply amount (higher hydraulic pressure) than the retard working chamber 204 by the control of the exhaust side first direction switching valve 84, the camshaft 53 By rotating in the rotational direction, the opening timing of the exhaust valve 51 is advanced and set to the advance side.
On the other hand, when oil is supplied to the retarded working chamber 204 with a larger supply amount (higher hydraulic pressure) than the advanced working chamber 203 by the control of the exhaust side first direction switching valve 84, the camshaft 53 is moved in its rotational direction. Is rotated in the opposite direction, and the opening timing of the exhaust valve 51 is delayed and set to the retard side.

(Control system)
The engine 1 is controlled by an ECU (Electric Control Unit) 110.
The ECU 110 executes all-cylinder operation by the first to fourth cylinders when the execution condition for all-cylinder operation is satisfied, and stops the operation by the first and fourth cylinders when the execution condition for reduced-cylinder operation is satisfied. In addition, a reduced-cylinder operation is performed in which only the operation by the second and third cylinders is performed.
The ECU 110 includes a CPU (Central Processing Unit), a ROM, a RAM, an in-side interface, an out-side interface, and the like.
As shown in FIG. 5, the ECU 110 includes a hydraulic pressure sensor 90, a vehicle speed sensor 91, an accelerator opening sensor 92, a gear position sensor 93, an intake manifold pressure sensor 94, an intake air amount sensor 95, and an intake air temperature sensor 96. The intake pressure sensor 97, the crank angle sensor 98, the cam angle sensor 99, the oil temperature sensor 100, the oil level sensor 101, the water temperature sensor 102, the turning acceleration sensor 103, and the like are electrically connected.

The vehicle speed sensor 91 detects the traveling speed of the vehicle, and the accelerator opening sensor 92 detects the amount of depression of an accelerator pedal (not shown) by the occupant. The gear stage sensor 93 detects a transmission gear stage currently set in the transmission mounted on the vehicle, and the intake manifold pressure sensor 94 detects the pressure in the intake manifold. The intake air amount sensor 95 detects the intake air amount, the intake air temperature sensor 96 detects the intake air temperature, and the intake pressure sensor 97 detects the intake air pressure. The crank angle sensor 98 detects the rotation angle of the crankshaft 7 and detects the engine rotation speed based on this rotation angle. The cam angle sensor 99 detects the rotation angles of the cam shafts 43 and 53, and detects the rotation phases of the cam shafts 43 and 53 and the phases of the VVTs 19 and 20 based on the rotation angles. The oil temperature sensor 100 detects the oil temperature (oil temperature) flowing through the oil supply passage 70. The oil level sensor 101 detects the oil level stored in the oil pan 5, and the water temperature sensor 102 detects the cooling water temperature for circulating and cooling the engine 1. The turning acceleration sensor 103 detects turning acceleration that acts on the vehicle during turning.
The detection values by these sensors 90 to 103 are output to the ECU 110, and the operation of the engine 1 is controlled.

This ECU 110 is based on the detected values of the sensors 90 to 103 based on the detected values of the sensors 90 to 103 so that the total torque (requested torque) output from the engine 1 becomes substantially constant when switching from one operation to the other operation. The spark plug 13, the HLA 14, the VVTs 19 and 20, the throttle valve 25, and the exhaust shutter valve 35 are coordinated and controlled in time series.
As shown in FIG. 5, the ECU 110 includes an operation condition determination unit 111, a VVT control unit 112, an ignition timing control unit 113, a fuel control unit 114, a throttle valve control unit 115, and a valve stop mechanism control unit 116. And an exhaust shutter valve control unit 117 and the like.

First, the operating condition determination unit 111 will be described.
The operation condition determination unit 111 determines whether or not to execute all-cylinder operation or reduced-cylinder operation based on the operation state.
As shown in FIG. 6, the operation condition determination unit 111 stores in advance a map M in which the all-cylinder operation region A1 and the reduced-cylinder operation region A2 are set, and any operation based on the map M and the operation conditions. It is determined whether the execution condition is satisfied.
In the map M, the horizontal axis is defined by the engine speed, and the vertical axis is defined by the target indicated torque.
The reduced cylinder operation region A2 has a region range set by an engine speed lower limit value N1, an engine speed upper limit value N2 (N1 <N2), and a target indicated torque upper limit value L.
The target indicated torque upper limit L is set based on the maximum torque, the loss region branching torque, the intake pulsation restriction, etc. during the reduced-cylinder operation, and is set in a rearwardly rising inclination.

The target indicated torque is a basic torque calculated based on the target acceleration of the vehicle, and the output of the engine 1 and the shift speed control of the transmission are executed by this basic torque. Specifically, the target acceleration of the vehicle is set from the accelerator pedal depression amount, the vehicle speed, and the gear stage using a preset map (not shown), and the wheel torque is calculated based on the target acceleration.
After calculating the output torque and input torque of the transmission using this wheel torque to obtain the shaft torque necessary for the engine 1, the torque for correction such as auxiliary machine loss and mechanical loss is added to the engine shaft torque to obtain the final torque. Thus, the target indicated torque is obtained.

When a predetermined amount or more of air is mixed in the oil supplied to the valve stop mechanism 14b, the responsiveness and followability of the valve stop mechanism 14b are deteriorated. Therefore, the operation condition determination unit 111 restricts the operation switching even when the condition for executing the switching from the all-cylinder operation to the reduced-cylinder operation is satisfied when the air supplied to the oil supplied to the valve stop mechanism 14b is assumed. Yes.
In the present embodiment, the situation in which air is mixed into the oil supplied to the valve stop mechanism 14b is determined based on the oil level, the turning acceleration, and the oil temperature.
When the oil level is low, air is sucked from the oil strainer 18 to increase the amount of air contained in the oil, and when the turning acceleration is large, the oil stored in the oil pan 5 is mixed with the air and contained in the oil. This is because when the amount of air generated increases and the oil temperature is high, the viscosity of the oil decreases and air is introduced into the oil, increasing the amount of air contained in the oil.

This operating condition determination unit 111 includes a lower limit determination temperature T1a and an upper limit determination temperature T1b (T1a <T1b) as the oil temperature determination temperature, a lower limit determination temperature T2a and an upper limit determination temperature T2b (T2a <T2b) as the water temperature determination temperature, and an oil A level determination value D and a turning acceleration determination value G are stored in advance. The lower limit determination temperature T1a is set based on the viscosity capable of maintaining the responsiveness and followability of the valve stop mechanism 14b due to the physical properties of the oil, and the upper limit determination temperature T1b is an oil that can block the air introduced into the oil. It is set based on viscosity. The lower limit determination temperature T2a and the upper limit determination temperature T2b are set based on the combustibility of the engine 1.
The determination value D corresponds to an oil level such that the surface (upper surface) is positioned a predetermined distance above the suction portion of the oil strainer 18 when the vehicle is in a horizontal state. The judgment value G corresponds to the turning acceleration at which the oil is biased to one side by centrifugal force at the average oil level and the suction part of the oil strainer 18 comes out of the oil.

  The operating condition determination unit 111 is when the coolant temperature is lower than the lower limit determination temperature T2a and higher than the upper limit determination temperature T2b, or when the oil temperature is lower than the lower limit determination temperature T1a and higher than the upper limit determination temperature T1b, or When the level is equal to or lower than the determination value D or when the turning acceleration is equal to or higher than the determination value G, even if the driving state exists in the reduced-cylinder operation region A2, it is not determined that the reduced-cylinder operation execution condition is satisfied. Therefore, it is determined that the all-cylinder operation execution condition is satisfied, and the reduced-cylinder operation is prohibited.

The ECU 110 does not immediately execute the reduced-cylinder operation for stopping the first and fourth cylinders even when the operation condition determining unit 111 determines that the execution condition for the reduced-cylinder operation is satisfied, and prepares for executing the reduced-cylinder operation. It is comprised so that a process may be implemented.
In the reduced-cylinder operation, the intake and exhaust valves 41 and 51 of the first and fourth cylinders are closed, the VVTs 19 and 20 are set on the retard side, and the opening of the throttle valve 25 is set on the increase side.
Therefore, in the preparatory process, the hydraulic pressure is increased to the switching target hydraulic pressure higher than the holding hydraulic pressure supplied to the HLA 14 in order to keep the intake and exhaust valves 41 and 51 of the first and fourth cylinders closed, and the VVT 19 , 20 are controlled to the retard side, and the opening of the throttle valve 25 is controlled to the increase side. Here, in order to make the required torque constant by the engine 1, the ignition timing is controlled to the retard side during the increase side control period of the throttle valve 25, and the ignition timing is retarded to suppress the deterioration of fuel consumption. In consideration of shortening the side control period, the opening operation of the throttle valve 25 is increased after the target hydraulic pressure increase operation for switching and the retarding operation of the VVTs 19 and 20 are completed.
Furthermore, since the amount of hydraulic pressure consumed by the retarding operation of the VVT 20 is large, a decrease in the hydraulic pressure supplied to the HLA 14 or a fluctuation in the hydraulic pressure such as overshoot or undershoot occurs, and the operation switching time becomes longer. The target hydraulic pressure increase operation for switching is performed after the end of the retard operation. As described above, when the operation condition determination unit 111 determines that the reduced cylinder operation execution condition is satisfied, first, the retard operation of the VVTs 19 and 20 is started.

Next, the VVT control unit 112 will be described.
The VVT control unit 112 sets the target phase for the reduced cylinder operation of the VVTs 19 and 20 based on the air charging efficiency (ce) at the time of the operation switching from the all cylinder operation to the reduced cylinder operation (hereinafter referred to as the reduced cylinder operation switching). In addition, the electric motor 191 and the exhaust-side first direction switching valve 84 are retarded. The VVT control unit 112 gradually controls to the retard side so that the target phase for reduced-cylinder operation becomes the target phase for reduced-cylinder operation when switching to reduced-cylinder operation, and switches the operation from reduced-cylinder operation to all-cylinder operation. At the time (hereinafter, referred to as all cylinder operation switching), the control is gradually made to advance to the all cylinder operation target phase from the reduced cylinder operation target phase.

The VVT control unit 112 stores in advance a control map (not shown) in which the relationship between the air filling efficiency and the target phase is set.
As shown in FIG. 7, the intake is determined based on the pressure in the intake manifold detected by the intake manifold pressure sensor 94, the intake air amount detected by the intake air amount sensor 95, and the intake air temperature detected by the intake air temperature sensor 96. The pressure in the manifold is calculated.
Further, the volumetric efficiency ηvp in the intake manifold is calculated based on the engine speed, the phases of the VVTs 19 and 20, the intake manifold pressure and the exhaust pressure.
The air charging efficiency of the engine 1 is calculated from the intake manifold internal pressure and the volumetric efficiency ηvp.

Since the operation of the VVT 20 is stopped and the phase of the VVT 20 is fixed while the hydraulic pressure is raised toward the target hydraulic pressure for switching, the operating state may change. Therefore, in this embodiment, after the switching target hydraulic pressure increase operation and before the opening operation of the throttle valve 25, the correction control is performed to correct the phase of the VVT 20 to the correction target phase for reduced cylinder operation. .
Since this correction control is a small amount of operation compared to the initial retardation operation, the hydraulic pressure fluctuation is small.
Note that when the operating state does not change during the switching target hydraulic pressure boost operation, the correction control of the VVT 20 is omitted.
Since the VVT 19 is driven by the electric motor 191 and does not affect the switching target hydraulic pressure boosting operation, the operation is continued even during the switching target hydraulic pressure boosting operation.
Further, the advance operation speed of the exhaust valve 51 may be slower than the advance operation speed of the intake valve 41 in order to ensure the overlap amount of the intake and exhaust valves 41 and 51 during the shift to the advance side. In this case, the operating speeds of the intake and exhaust valves 41 and 51 are adjusted based on the hydraulic pressure and the oil temperature.

Next, the ignition timing control unit 113 will be described.
The ignition timing control unit 113 determines the ignition timing according to the driving state of the vehicle, and outputs an ignition execution command to the spark plug 13. The ignition timing control unit 113 stores in advance an ignition timing map (not shown) set by the engine speed and the engine load substituted by the accelerator opening, and extracts the ignition timing based on this map. The basic ignition timing is set based on the intake pressure detected by the intake pressure sensor 97 with the extracted ignition timing.
Two types of ignition timing maps are prepared for all cylinder operation and reduced cylinder operation.

The ignition timing control unit 113 is gradually retarded toward the target basic ignition timing in accordance with the operation of increasing the opening of the throttle valve 25 (the air charging efficiency of each cylinder) at the time of switching the reduced cylinder operation. At the time of all-cylinder operation switching, the target is gradually advanced toward the basic ignition timing at the time of all-cylinder operation in accordance with the decreasing operation of the throttle valve 25.
The retard amount during retarded cylinder operation switching and during all cylinder operation switching is set to be inversely proportional to the internal EGR amount flowing into the cylinder bore 9 of each cylinder. The ignition timing retardation control at the time of switching the reduced cylinder operation and at the time of switching all the cylinder operations is once canceled after the start of the reduced cylinder operation, and returned to the retard amount before the cancellation again at the time of switching all the cylinder operations.

Next, the fuel control unit 114 and the throttle valve control unit 115 will be described.
The fuel control unit 114 determines the fuel injection amount and timing according to the operating state, and outputs an injection execution command to the injector 12. The fuel control unit 114 stores a fuel injection map (not shown) preset by the target indicated torque, and sets the fuel injection amount and timing based on this map.
Further, the fuel control unit 114 switches the control of the injectors 12 of the idle cylinders (first and fourth cylinders) according to the all cylinder operation or the reduced cylinder operation. That is, during the all-cylinder operation, the fuel injection is performed by driving the injectors 12 of the first to fourth cylinders, while during the reduced-cylinder operation, the fuel injection by the injectors 12 of the first and fourth cylinders is prohibited.

The throttle valve control unit 115 controls the opening of the throttle valve 25 by controlling the actuator 26 so as to achieve the target indicated torque. This throttle valve control unit 115 reduces the number of cylinders that are operated during the reduced cylinder operation, so the output per cylinder of the cylinders that are operating (second and third cylinders) is output as one cylinder during the entire cylinder operation. The opening degree of the throttle valve 25 is controlled to increase toward the opening side so that the output is larger than the hit output.
In addition, the throttle valve control unit 115 starts an operation of increasing the opening of the throttle valve 25 to the target air charging efficiency at the time of the reduced cylinder operation after the completion of the correction control by the VVT 20 when the reduced cylinder operation is switched. At the time of switching, simultaneously with the start of control of the VVTs 19 and 20 to the advance side, the operation of reducing the opening of the throttle valve 25 to the target air charging efficiency during all cylinder operation is started.

Next, the valve stop mechanism control unit 116 will be described.
The valve stop mechanism control unit 116 switches the control of the linear solenoid valve 89 according to whether all cylinder operation or reduced cylinder operation. The valve stop mechanism control unit 116 turns off the linear solenoid valve 89 during all cylinder operation to enable the opening and closing operations of the intake and exhaust valves 41 and 51 of the first to fourth cylinders. The linear solenoid valve 89 is turned on to maintain the hydraulic pressure supplied to the HLA 14 at the closed state holding hydraulic pressure, and the intake / exhaust valves 41 and 51 of the idle cylinders are maintained in the closed state.

The valve stop mechanism control unit 116 switches the oil pressure by the exhaust side second direction switching valve 85 after the air filling efficiency of each cylinder reaches the target air filling efficiency at the time of the reduced cylinder operation at the time of switching the reduced cylinder operation. And the exhaust valve 51 is closed, and then the intake valve 41 is closed by the intake side second direction switching valve 86.
Further, the valve stop mechanism control unit 116 opens the exhaust valve 51 by the exhaust side second direction switching valve 85 and then opens the intake valve 41 by the intake side second direction switching valve 86 at the time of all cylinder operation switching.

Next, the exhaust shutter valve control unit 117 will be described.
The exhaust shutter valve control unit 117 controls the exhaust shutter valve 35 to the closed side during the reduced-cylinder operation, and the exhaust pressure upstream of the exhaust shutter valve 35 is set to the set pressure (for example, the exhaust valve 51) during the all-cylinder operation. The exhaust shutter valve 35 is controlled to be equal to or lower than (seal pressure).
The exhaust shutter valve control unit 117 is set so that a predetermined exhaust gas flows when the exhaust shutter valve 35 is in the fully closed position and becomes atmospheric pressure at the fully open position. The pressure can be estimated.

Next, the operation condition determination processing content will be described based on the flowchart of FIG.
Si (i = 101, 102...) Indicates a step for each process.
As shown in the flowchart of FIG. 8, first, in S101, the output values of the sensors 90 to 103, the maps, and various types of information are read, and the process proceeds to S102.
In S102, it is determined whether or not the current engine speed is not less than the lower limit value N1 and not more than the upper limit value N2.

If the current engine speed is not less than the lower limit value N1 and not more than the upper limit value N2 as a result of the determination in S102, it is determined whether or not the current target indicated torque is not more than the upper limit value L (S103).
If the current target indicated torque is equal to or lower than the upper limit value L as a result of the determination in S103, the current operation state exists in the reduced-cylinder operation region A2, so that the cooling water temperature is equal to or higher than the lower limit determination temperature T2a and lower than the upper limit determination temperature T2b Whether or not is determined (S104).
If the result of the determination in S104 is that the coolant temperature is not less than the lower limit determination temperature T2a and not more than the upper limit determination temperature T2b, it is determined whether the oil temperature is not less than the lower limit determination temperature T1a and not more than the upper limit determination temperature T1b (S105).

As a result of the determination in S105, if the oil temperature is not lower than the lower limit determination temperature T1a and not higher than the upper limit determination temperature T1b, it is determined whether or not the oil level is higher than the determination value D (S106).
If the result of determination in S106 is that the oil level is greater than the determination value D, it is determined whether or not the turning acceleration is less than the determination value G (S107).
As a result of the determination in S107, if the turning acceleration is less than the determination value G, it is determined that the reduced-cylinder operation execution condition is satisfied (S108), and the process returns.

If the current engine speed is less than the lower limit value N1 or exceeds the upper limit value N2 as a result of the determination in S102, or if the current target indicated torque exceeds the upper limit value L as a result of the determination in S103, the current operating state is the map M Therefore, it is determined that the all-cylinder operation execution condition is satisfied (S109), and the process returns.
If the cooling water temperature is less than the lower limit determination temperature T2a or exceeds the upper limit determination temperature T2b as a result of the determination in S104, or if the oil temperature is lower than the lower limit determination temperature T1a or exceeds the upper limit determination temperature T1b as a result of the determination in S105, the reduced cylinder operation is performed. Since this is an unsuitable operating condition, it is determined that the all-cylinder operation execution condition is satisfied (S109), and the process returns.
As a result of the determination in S106, if the oil level is equal to or less than the determination value D, if the turning acceleration is equal to or greater than the determination value G as a result of the determination in S107, the operation condition is not suitable for reduced-cylinder operation. (S109) and return.

Next, the contents of the control process will be described based on the flowchart of FIG. 9 and the time chart of FIG. This control process is processed in parallel with the operation condition determination process.
Si (i = 201, 202...) Indicates steps for each process, and t1 to t12 indicate time points in the time chart.

As shown in the flowchart of FIG. 9, first, in S201, various information is read, and the process proceeds to S202.
In S202, it is determined whether or not the reduced cylinder operation execution condition is satisfied.
As a result of the determination in S202, when it is determined that the reduced-cylinder operation execution condition is satisfied (t1), a VVT retardation operation is performed on the intake and exhaust valves 41 and 51 to execute a preparation process for reduced-cylinder operation (S203). , The process proceeds to S204.

In S204, it is determined whether or not the phase of the exhaust valve 51 has reached the target phase for reduced cylinder operation.
As a result of the determination in S204, when the phase of the exhaust valve 51 has reached the target phase for reduced cylinder operation (t2), the linear solenoid valve 89 is turned on (S205), and the process proceeds to S206. Since the hydraulic pressure supply to the exhaust side VVT 20 is stopped at the time t2 when the phase of the exhaust valve 51 reaches the target phase for reduced cylinder operation, the hydraulic pressure fluctuation due to the phase change of the exhaust valve 51 is suppressed.
As a result of the determination in S204, if the phase of the exhaust valve 51 has not reached the target phase for reduced cylinder operation, the process returns to S203 to continue the VVT retardation operation of the exhaust valve 51.

In S206, it is determined whether or not the oil pressure in the oil passage 70 has exceeded the switching target oil pressure.
As a result of the determination in S206, when the oil pressure in the oil passage 70 exceeds the switching target oil pressure (t3), it is determined whether or not the operating state has changed during the pressure increasing operation period (S207).
As a result of the determination in S206, if the oil pressure in the oil passage 70 does not exceed the target oil pressure for switching, the process returns to S205 to continue the ON state of the linear solenoid valve 89 and continue the pressure increase.
As a result of the determination in S207, if there is a change in the operating state during the boosting operation period, the target phase for reduced cylinder operation is not compatible with the current operating state, so the exhaust side first direction switching valve 84 is further operated. VVT correction control is executed (S208), and the process proceeds to S209.

In S209, it is determined whether the phase of the exhaust valve 51 has reached the correction target phase for reduced cylinder operation.
As a result of the determination in S209, when the phase of the exhaust valve 51 has reached the correction target phase for reduced cylinder operation (t4), the process proceeds to S210.
As a result of the determination in S209, if the phase of the exhaust valve 51 has not reached the correction target phase for reduced cylinder operation, the process returns to S208 to continue the VVT correction control of the exhaust valve 51.
As a result of the determination in S207, if there is no change in the operating state during the boost operation period, the target phase for reduced-cylinder operation is adapted to the current operating state, and the process proceeds to S210.
In S210, the throttle valve increasing operation for increasing the opening of the throttle valve 25 and the ignition timing retarding control for retarding the ignition timing are started (t4), and the process proceeds to S211.

In S211, it is determined whether the air charging efficiency exceeds the target air charging efficiency during the reduced-cylinder operation.
As a result of the determination in S211, when the air charging efficiency exceeds the target air charging efficiency during the reduced-cylinder operation (t5), the valve closing operation of the intake and exhaust valves 41 and 51 is executed (S212), and the process proceeds to S213. The timing for starting the closing operation of the exhaust valve 51 is started earlier than the timing for starting the closing operation of the intake valve 41.
As a result of the determination in S211, if the air charging efficiency does not exceed the target air charging efficiency during the reduced cylinder operation, the process returns to S210 and the throttle valve increasing operation is continued.
In S213, after the intake / exhaust valves 41 and 51 are closed, the fuel injection of the first and fourth cylinders is prohibited and the ignition timing retarding control is prohibited and returned (t6), and the process proceeds to S214.
At this time, the hydraulic pressure supplied to the HLA 14 is adjusted from the switching target hydraulic pressure to the valve closing holding hydraulic pressure. The start of the reduced cylinder operation is started from t7 due to the followability of the hydraulic pressure. Therefore, the period between t5 and t7 is a switching transition period.
In S214, exhaust shutter valve control is executed, the flag is changed to 1 (S215), and the process returns.

As a result of the determination in S202, when it is not determined that the reduced-cylinder operation execution condition is satisfied, the process proceeds to S216, and it is determined whether or not the flag is 1.
Flag 0 is set during all cylinder operation, and flag 1 is set during reduced cylinder operation.
As a result of the determination in S216, when the flag is 1, since it is determined that the all-cylinder operation execution condition is satisfied during the reduced-cylinder operation (t8), the reduced-cylinder operation is terminated and the process proceeds to S217.
In S217, the prohibition of fuel injection of the first and fourth cylinders is canceled and the prohibition of ignition timing retardation control is canceled (t9), and the process proceeds to S218.
The ignition timing retarding control for all-cylinder operation switching is temporarily returned to the ignition timing at the time of switching the reduced-cylinder operation, and the ignition timing at the time of switching the reduced-cylinder operation is set as the initial ignition timing. In addition, since the valve closing operation release of the intake and exhaust valves 41 and 51 of the first and fourth cylinders is not completed, the operation of the injector 12 and the spark plug 13 is not started.
In S218, the exhaust shutter valve control is terminated, the valve closing operation of the intake / exhaust valves 41 and 51 is released (S219), and then the linear solenoid valve 89 is operated in the off state (S220).
The opening operation start timing of the exhaust valve 51 is started earlier than the opening operation start timing of the intake valve 41.
In S221, it is determined whether or not the hydraulic pressure supplied to the HLA 14 has dropped from the valve closing holding hydraulic pressure to the target hydraulic pressure during all cylinder operation.

As a result of the determination in S221, when the hydraulic pressure supplied to the HLA 14 drops from the valve closing holding hydraulic pressure to the target hydraulic pressure during all cylinder operation (t10), the flow proceeds to S222. The start of all-cylinder operation is started from t10 when the release operation of the intake and exhaust valves 41 and 51 of the first and fourth cylinders is completed. Therefore, the period between t8 and t10 is a switching transition period.
As a result of the determination in S221, if the hydraulic pressure supplied to the HLA 14 has not decreased from the valve closing holding hydraulic pressure to the target hydraulic pressure during all cylinder operation, the process returns to S20 to continue the OFF state of the linear solenoid valve 89 and reduce the pressure. continue.

In S222, the throttle valve increasing operation is terminated and the opening of the throttle valve 25 is gradually decreased, the VVT retarding operation is terminated, and the phase of the VVT 20 is gradually controlled to the advance side. The fuel injection is performed, and the advance angle control is executed to gradually control the ignition timing to the advance side. As a result, the opening degree of the throttle valve 25 reaches the opening degree corresponding to the target air charging efficiency in the all cylinder operation (t11), and the phase of the VVT 20 reaches the all cylinder operation target phase (t12).
In S223, the flag is changed to 0 and the process returns.
If the result of determination in S216 is that the flag is not 1, since the previous operation state is all-cylinder operation, all-cylinder operation is continued (S224) and the process returns.

Next, the operation and effect of the engine control apparatus will be described.
According to the present control device, when the air supplied to the oil supplied to the valve stop mechanism 14b is assumed, the ECU 110 limits the operation switching even if the condition for executing the switching from the all-cylinder operation to the reduced-cylinder operation is satisfied. Therefore, it is possible to limit the switching operation in a state where air that is a compressed fluid is mixed in the oil, and it is possible to prevent the operation switching time from being prolonged. That is, the responsiveness and followability of the valve stop mechanism 14b can be maintained regardless of the driving state, and the operability of the vehicle can be improved.

  The ECU 110 has an oil level sensor 101 that can detect the oil level of the oil pan 5 that stores oil supplied to the valve stop mechanism 14b, and the ECU 110 detects when the oil level detected by the oil level sensor 101 is equal to or less than a determination value D. Since it is determined that the oil supplied to the valve stop mechanism 14b is in an operating state in which air is expected to be mixed, the oil level can be determined as a parameter for the operating state in which air is expected to be mixed in the oil. That is, it is possible to determine a state in which air is sucked from the oil strainer 18 and the amount of air in the oil increases according to the oil level.

  The ECU 110 includes a turning acceleration sensor 103 that can detect turning acceleration of the vehicle. When the turning acceleration detected by the turning acceleration sensor 103 is equal to or higher than a determination value G, air is mixed into the oil supplied to the valve stop mechanism 14b. Since it is determined as the assumed driving state, the turning acceleration can be determined as a parameter for the driving state in which air is assumed to be mixed in the oil. That is, the state in which the oil stored in the oil pan 5 is agitated with air can be determined based on the turning acceleration.

  The ECU 110 has an oil temperature sensor 100 that can detect the oil temperature supplied to the valve stop mechanism 14b, and the ECU 110 supplies the oil temperature to the valve stop mechanism 14b when the oil temperature detected by the oil temperature sensor 100 is larger than the determination value T1b. Therefore, it is possible to determine the oil temperature as a parameter for the operation state in which air is assumed to be mixed in the oil. That is, it is possible to determine a state in which the viscosity of the oil is lowered and the air is easily introduced into the oil depending on the oil temperature.

  When the ECU 110 determines that the oil supplied to the valve stop mechanism 14b is in an operating state in which air is expected to be mixed, the operation switching in a state in which air is mixed in the oil is prohibited in order to prohibit the switching to the reduced-cylinder operation. The operation can be prohibited, and the prolonged operation switching time can be surely prevented.

Next, the operation condition determination processing content according to the second embodiment will be described.
In the first embodiment, the single reduced-cylinder operation region A2 set in the map M is fixed, whereas in the second embodiment, two types of the reduced-cylinder operation region A2 are set according to the operation state. .
The operation condition determination unit 111 includes a first reduced-cylinder operation region A2 used during normal operation, and a second reduced-cylinder operation region A2 used during operation in which air is assumed to be mixed in the oil.
As in the first embodiment, the first reduced-cylinder operation region A2 has a region range defined by an engine speed lower limit value N1, an engine speed upper limit value N2, and a target indicated torque upper limit value L.
In the second reduced-cylinder operation region A2, as indicated by a broken line in FIG. 6, the engine speed upper limit value N2 is set to be lower by ΔN than the upper limit value N2 of the first reduced-cylinder operation region A2.

Next, the contents of the operation condition determination process will be described based on the flowchart of FIG.
As shown in the flowchart of FIG. 11, first, in S301, the output value of each sensor 90-103, each map, and various information are read, and the process proceeds to S302.
In S302, it is determined whether or not the oil level is higher than a determination value D.
As a result of the determination in S302, if the oil level is higher than the determination value D, it is determined whether the turning acceleration is less than the determination value G (S303).
As a result of the determination in S303, when the turning acceleration is less than the determination value G, the first reduced-cylinder operation region A2 is selected (S304).
As a result of the determination in S302, if the oil level is equal to or lower than the determination value D, the second reduced-cylinder operation region A2 is selected if the turning acceleration is equal to or higher than the determination value G as a result of determination in S303 (S311).

In S305, it is determined whether or not the current engine speed is not less than the lower limit value N1 and not more than the upper limit value N2.
As a result of the determination in S305, if the current engine speed is not less than the lower limit value N1 and not more than the upper limit value N2, it is determined whether or not the current target indicated torque is not more than the upper limit value L (S306).
As a result of the determination in S306, if the current target indicated torque is equal to or lower than the upper limit value L, the current operation state exists in the reduced cylinder operation region A2, so whether the cooling water temperature is equal to or higher than the lower limit determination temperature T2a and the upper limit determination temperature T2b. It is determined whether or not (S307).
If the result of determination in S307 is that the coolant temperature is not lower than the lower limit determination temperature T2a and not higher than the upper limit determination temperature T2b, it is determined whether the oil temperature is not lower than the lower limit determination temperature T1a and not higher than the upper limit determination temperature T1b (S308).
As a result of the determination in S308, if the oil temperature is not lower than the lower limit determination temperature T1a and not higher than the upper limit determination temperature T1b, it is determined that the reduced-cylinder operation execution condition is satisfied (S309), and the process returns.

As a result of the determination in S305, if the current engine speed is less than the lower limit value N1 or exceeds the upper limit value N2, if the current target indicated torque exceeds the upper limit value L as a result of the determination in S306, it is within the reduced cylinder operation region A2. Since it does not exist, it is determined that the all-cylinder operation execution condition is satisfied (S310), and the process returns.
As a result of the determination in S307, when the cooling water temperature is less than the lower limit determination temperature T2a or exceeds the upper limit determination temperature T2b, and as a result of the determination in S308, if the oil temperature is lower than the lower limit determination temperature T1a or exceeds the upper limit determination temperature T1b, the reduced cylinder operation is performed. Since this is an unsuitable operating condition, it is determined that the all-cylinder operation execution condition is satisfied (S310), and the process returns.
According to the present control device, since the operation switching operation in the high-speed operation region where air is likely to be mixed into the oil is limited, it is possible to achieve both improvement in fuel efficiency and ensuring the performance of the valve stop mechanism 14b.

Next, a modified example in which the embodiment is partially changed will be described.
1) In the above embodiment, an example of an in-line four-cylinder gasoline engine has been described. However, the present invention can be applied without being limited to an engine type such as a six-cylinder engine or a V-type engine. It is not limited to cylinder gasoline engines.
Further, the example of the engine that performs the reduced cylinder operation in which half of the four cylinders are deactivated has been described, but the number of deactivated cylinders may be arbitrarily set.

2] In the above-described embodiment, the example of the second reduced cylinder operation region in which the upper engine speed upper limit value in the first reduced cylinder operation region has been described has been described. However, both the engine rotational speed upper limit value and the target indicated torque upper limit value are A reduced second reduced cylinder operating region may be used.

3) In the above-described embodiment, the example in which the first and second reduced-cylinder operation areas are set according to the oil level and the turning acceleration has been described. And may be controlled to 2 or more according to the level at which air is expected to be mixed into the oil. Further, the reduced cylinder operating region may be controlled linearly after weighting the oil level and the turning acceleration.

4) In addition, those skilled in the art can implement the present invention in a form in which various modifications are added to the above-described embodiment or in a form in which each embodiment is combined without departing from the gist of the present invention. Various modifications are also included.

1 Engine 14b Valve stop mechanism 41 Intake valve 51 Exhaust valve 101 Exhaust gas temperature sensor 110 ECU
113 Ignition timing control unit 115 Throttle valve control unit 117 Exhaust shutter valve control unit

Claims (6)

A plurality of cylinders and a deactivation cylinder for deactivating a part of the cylinders are established, and a deactivation cylinder is set from the plurality of cylinders and an intake valve and an exhaust valve of the deactivation cylinder are closed. In an engine control device comprising a hydraulic valve stop mechanism for valve and a control means for controlling the hydraulic valve stop mechanism,
The control means restricts the operation switching even if the condition for executing the switching from the all-cylinder operation to the reduced-cylinder operation is satisfied, when air mixing is assumed in the oil supplied to the hydraulic valve stop mechanism. An engine control device. An oil level detecting means capable of detecting an oil level of an oil pan for storing oil supplied to the hydraulic valve stop mechanism;
The control means determines that the oil supplied to the hydraulic valve stop mechanism is assumed to be in an operating state when the oil level detected by the oil level detection means is equal to or less than a determination value. The engine control device according to claim 1. A turning acceleration detecting means capable of detecting turning acceleration of the vehicle;
The control means determines that the oil supplied to the hydraulic valve stop mechanism is assumed to be in an operating state when the turning acceleration detected by the turning acceleration detecting means is equal to or greater than a determination value. The engine control device according to claim 1. Oil temperature detection means capable of detecting the oil temperature supplied to the hydraulic valve stop mechanism;
The control means determines that the oil supplied to the hydraulic valve stop mechanism is assumed to be in an operating state when the oil temperature detected by the oil temperature detection means is larger than a determination value. The engine control device according to claim 2 or 3.   The said control means prohibits the driving | operation switching to a reduced cylinder driving | running, when it determines with the driving | running state in which air mixing is assumed to the oil supplied to the said hydraulic valve stop mechanism. The engine control device according to any one of the above.   When the engine operating state is a reduced cylinder operation region defined by the engine speed and the target indicated torque, the control means determines whether or not the execution condition for switching from all cylinder operation to reduced cylinder operation is satisfied, and the hydraulic type 5. The upper limit value of the engine speed in the reduced-cylinder operation region is lowered when it is determined that the oil supplied to the valve stop mechanism is in an operating state in which air is expected to be mixed. The engine control device according to claim 1.