JP2016151230A - Control device of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further surely enhance fuel economy in an engine in which a reduced-cylinder operation is performed.SOLUTION: A reduced-cylinder operation continuation time tr being a time up to restoration to a full-cylinder operation region A2, a reduction amount IEF of a fuel consumption rate at the execution of a reduced-cylinder operation, and a fuel economy deterioration amount DEF being an increase amount of a fuel consumption amount accompanied by the execution of preparation control are calculated by executing the preparation control for making ignition timing retard while increasing an intake amount before a start of the reduced-cylinder operation, a final fuel economy improvement amount IEF_f being a reduction amount of the fuel consumption amount accompanied by changeover to the reduced-cylinder operation is calculated on the basis of these calculation items, the reduced-cylinder operation is started when the final fuel economy improvement amount IEF_f is not smaller than a reference amount, and on the other hand, when the final fuel economy improvement amount IEF_f is smaller than the reference amount, a normal full-cylinder operation is executed irrespective of whether or not the preparation control is in execution.SELECTED DRAWING: Figure 10

Description

  The present invention is provided between the all-cylinder operation in which the combustion of the air-fuel mixture is performed in all the cylinders and the reduced-cylinder operation in which the combustion in the specific cylinder is stopped and the specific cylinder is brought into a resting state. The present invention relates to a device for controlling a switchable engine.

  Conventionally, various studies have been conducted to improve the fuel efficiency of an engine. As one technique for improving fuel consumption performance, as disclosed in Patent Document 1, in a multi-cylinder engine having a plurality of cylinders, combustion in some cylinders is stopped in a predetermined operation region, and A technique is known in which an intake valve and an exhaust valve are held closed to make these cylinders inactive, and the operation is performed only with the remaining cylinders.

JP 58-187508 A

  According to the above technique, by stopping some of the cylinders, it is possible to reduce the pumping loss caused by operating these cylinders and improve the fuel efficiency.

  However, the present inventors have found that depending on the operating state of the engine, the fuel efficiency performance of the engine may not be sufficiently improved even when the operation of stopping some cylinders is performed. That is, for example, in order to perform a reduced cylinder operation in which some cylinders are deactivated, it is necessary to switch between this reduced cylinder operation and an all cylinder operation in which combustion is performed in all cylinders. As a result of an increase in energy loss caused by this switching depending on the driving state, it has been found that there is a possibility that the fuel efficiency of the engine cannot be sufficiently improved even if the reduced-cylinder operation is performed.

  The present invention has been made in view of the circumstances as described above, and an object of the present invention is to provide an engine control device that can improve fuel efficiency more reliably by performing reduced-cylinder operation.

  In order to solve the above problems, the present invention has a plurality of cylinders equipped with an intake valve and an exhaust valve, and performs all-cylinder operation in which a mixture is burned in all cylinders in a predetermined all-cylinder operation region. An apparatus that controls an engine that performs a reduced cylinder operation by stopping combustion in a specific cylinder among a plurality of cylinders in a predetermined reduced cylinder operation region, and is provided in each cylinder. Control means for controlling each part of the engine, including ignition means for igniting the air-fuel mixture, intake air amount changing means for changing the intake air amount that is the amount of air sucked into each cylinder, and the ignition means and intake air amount control means And the control means is a final fuel consumption that is a reduction in fuel consumption obtained by switching from all-cylinder operation to reduced-cylinder operation until the reduced-cylinder operation is started in the reduced-cylinder operation region. Final fuel consumption by calculating the amount of improvement sequentially When the calculated final fuel consumption improvement amount is equal to or more than a preset reference amount in the good amount calculation unit and the reduced cylinder operation region, the intake amount of each cylinder is set to normal all-cylinder operation by the intake amount changing means. The preparatory control is performed to increase the intake amount at the time of reduced cylinder operation larger than the intake amount at the time and to retard the ignition timing of each cylinder from the ignition timing at the time of normal all-cylinder operation. A combustion control unit that starts the reduced cylinder operation when the intake amount becomes equal to or greater than the intake amount during the reduced cylinder operation. When it is confirmed that the amount is below the amount during execution of the preparation control, the preparation control is stopped and returned to the normal all-cylinder operation. Estimate the duration of reduced-cylinder operation, which is the time to return to The amount of fuel consumption per unit time when the reduced-cylinder operation is performed is reduced with respect to the amount of fuel consumed per unit time when the all-cylinder operation is performed based on the operating state of the engine. A fuel consumption improvement rate calculation unit that calculates a fuel consumption improvement rate; and a fuel consumption deterioration amount calculation unit that calculates a fuel consumption deterioration amount that is an increase in fuel consumption associated with the execution of the preparation control, and the estimated reduced-cylinder operation The final fuel consumption improvement amount is calculated based on the duration, the calculated fuel consumption improvement rate, and the calculated fuel consumption deterioration amount (Claim 1).

  According to the present invention, even in the reduced-cylinder operation region, it is estimated that the final fuel consumption improvement amount, which is the amount of reduction in fuel consumption accompanying the execution of reduced-cylinder operation, is larger than the reference amount and a sufficient fuel consumption improvement effect is obtained. Since the preparation control and the subsequent reduced-cylinder operation are started only when the engine is running, fuel consumption performance can be improved more reliably.

  In addition, in the present invention, preparation control is performed to retard the ignition timing while increasing the intake amount of each cylinder before the start of the reduced-cylinder operation. It is possible to avoid the occurrence of torque shock at the time of switching to operation.

  In particular, based on the operating state of the engine, the time until returning to the all-cylinder operation region, that is, the time continuously operated in the reduced-cylinder operation region (reduced cylinder operation continuation time), and the unit by performing the reduced-cylinder operation Estimate and calculate the fuel consumption (fuel efficiency improvement rate) that decreases per hour, calculate the fuel consumption deterioration amount that is the increase in fuel consumption accompanying the implementation of the preparation control, and based on these, calculate the final fuel improvement amount Therefore, the final fuel improvement amount can be estimated with higher accuracy.

  In the present invention, the final fuel improvement amount is continuously calculated until the reduced-cylinder operation is started, and the preparation control is performed when the final fuel consumption improvement amount becomes less than the reference amount even during the execution of the preparation control. Is stopped and returned to the normal all-cylinder operation, the fuel efficiency improvement effect obtained by the reduced-cylinder operation can be ensured more reliably.

  In the present invention, the final fuel consumption improvement amount calculation unit calculates a value obtained by multiplying the fuel consumption improvement rate by the reduced cylinder operation duration time as a fuel consumption improvement amount, and a value obtained by subtracting the fuel consumption deterioration amount from the fuel consumption improvement amount. Is preferably calculated as the final fuel consumption improvement amount (Claim 2).

  In this way, the final fuel consumption improvement amount can be accurately calculated.

  As described above, according to the engine control apparatus of the present invention, the fuel efficiency can be more reliably improved by performing the reduced-cylinder operation.

1 is a schematic plan view showing an overall configuration of an engine according to an embodiment of the present invention. It is sectional drawing of an engine main body. (A) It is a figure which shows a valve stop mechanism when a pivot part is a locked state. (B) It is a figure which shows the valve stop mechanism before a pivot part transfers to a lock release state. (C) It is a figure which shows a valve stop mechanism when a pivot part is a lock release state. It is the figure which showed the path | route of the hydraulic fluid of a valve stop mechanism. It is a block diagram which shows the control system of an engine. It is the figure which showed the all cylinder operation area | region and the reduced cylinder operation area | region. It is the flowchart which showed the determination procedure by the preparation control execution determination part. It is the figure which showed the relationship between a fuel consumption improvement rate and an engine load. It is the figure which showed the relationship between a fuel consumption deterioration amount, an engine speed, and an engine load. It is the flowchart which showed the control procedure in a reduced cylinder operation area | region.

(1) Overall Configuration of Engine FIG. 1 is a diagram showing an embodiment of an engine to which a control device of the present invention is applied. The engine shown in the figure is a 4-stroke multi-cylinder gasoline engine mounted on a vehicle as a power source for traveling. Specifically, this engine is generated by an in-line four-cylinder engine main body 1 having four cylinders 2A to 2D arranged in a straight line, an intake passage 30 for introducing air into the engine main body 1, and the engine main body 1. And an exhaust passage 35 for discharging the exhausted gas.

  FIG. 2 is a cross-sectional view of the engine body 1. As shown in the figure, an engine body 1 includes a cylinder block 3 in which the four cylinders 2A to 2D are formed, a cylinder head 4 provided on the upper side of the cylinder block 3, and an upper side of the cylinder head 4. It has a cam cap 5 provided and a piston 11 inserted into each of the cylinders 2A to 2D so as to be slidable back and forth.

  A combustion chamber 10 is formed above the piston 11, and fuel mainly composed of gasoline injected from an injector 12 (FIG. 1) is supplied to the combustion chamber 10. The supplied fuel burns in the combustion chamber 10, and the piston 11 pushed down by the expansion force due to the combustion reciprocates in the vertical direction.

  The piston 11 is connected to a crankshaft 15 that is an output shaft of the engine main body 1 via a connecting rod 14, and the crankshaft 15 rotates about the central axis in accordance with the reciprocating motion of the piston 11. .

  As shown in FIG. 1, the cylinder head 4 includes an injector 12 that injects fuel (gasoline) toward the combustion chamber 10 of each cylinder 2 </ b> A to 2 </ b> D as described above, and fuel and air injected from the injector 12. And an ignition plug (ignition means) 13 for igniting the air-fuel mixture by spark discharge. In the present embodiment, a total of four injectors 12 are provided at a rate of one for each cylinder, and a total of four spark plugs 13 are also provided at a rate of one for each cylinder.

  In the four-stroke four-cylinder gasoline engine as in the present embodiment, the pistons 11 provided in the cylinders 2A to 2D move up and down with a phase difference of 180 ° (180 ° CA) in crank angle. Correspondingly, the ignition timing in each of the cylinders 2A to 2D is also set to a timing shifted in phase by 180 ° CA. Specifically, in order from the left side of FIG. 1, assuming that the cylinder 2A is the first cylinder, the cylinder 2B is the second cylinder, the cylinder 2C is the third cylinder, and the cylinder 2D is the fourth cylinder, the first cylinder 2A → the third cylinder Ignition is performed in the order of 2C → fourth cylinder 2D → second cylinder 2B.

  The engine of the present embodiment is a variable cylinder engine capable of performing an operation in which two of the four cylinders 2A to 2D are stopped without burning and the remaining two cylinders are operated, that is, a reduced-cylinder operation. . For this reason, the ignition sequence as described above is for normal operation that is not reduced-cylinder operation (during all-cylinder operation in which all four cylinders 2A to 2D are operated). On the other hand, during the reduced-cylinder operation, the ignition operation of the spark plug 13 is prohibited in two cylinders (the first cylinder 2A and the fourth cylinder 2D in this embodiment) whose ignition order is not continuous, and ignition is performed by skipping one. become.

  As shown in FIGS. 1 and 2, the cylinder head 4 has an intake port 6 for introducing air (intake air) supplied from the intake passage 30 into the combustion chamber 10 of each cylinder 2A to 2D, and each cylinder 2A. The exhaust port 7 for leading the exhaust gas generated in the 2D combustion chamber 10 to the exhaust passage 35 and the opening on the combustion chamber 10 side of the intake port 6 for controlling the introduction of intake air through the intake port 6 are opened and closed. In order to control gas discharge from the exhaust port 7, an exhaust valve 9 for opening and closing the opening of the exhaust port 7 on the combustion chamber 10 side is provided. In the present embodiment, a total of eight intake valves 8 are provided at a rate of two per cylinder, and a total of eight exhaust valves 9 are also provided at a rate of two per cylinder.

  As shown in FIG. 1, the intake passage 30 includes four independent intake passages 31 communicating with the intake ports 6 of the cylinders 2 </ b> A to 2 </ b> D, and upstream ends of the individual intake passages 31 (on the upstream side in the intake flow direction). A surge tank 32 commonly connected to the end) and a single intake pipe 33 extending upstream from the surge tank 32. A throttle valve 34 a that can open and close a passage in the intake pipe 33 is provided in the middle of the intake pipe 33. The intake pipe 33 is provided with a throttle actuator 34b for driving the throttle valve 34a. The throttle valve 34a is opened and closed by the throttle actuator 34b. The flow rate of the intake air introduced into the engine body 1 is changed by opening and closing the throttle valve 34a, and the throttle valve 34a and the throttle actuator 34b can change the intake air amount that is the amount of air sucked into each cylinder. Function as.

  The exhaust passage 35 has four independent exhaust passages 36 communicating with the exhaust ports 7 of the cylinders 2A to 2D, and one downstream end portion (end portion on the downstream side in the exhaust gas flow direction) of each independent exhaust passage 36. And a single exhaust pipe 38 extending downstream from the collective portion 37.

(2) Valve Mechanism Next, a mechanism for opening and closing the intake valve 8 and the exhaust valve 9 will be described in detail with reference to FIGS. The intake valve 8 and the exhaust valve 9 are driven to open and close in conjunction with the rotation of the crankshaft 15 by a pair of valve mechanisms 28 and 29 disposed in the cylinder head 4.

  The valve operating mechanism 28 for the intake valve 8 includes a return spring 16 that urges the intake valve 8 in the closing direction (upward in FIG. 2), a cam shaft 18 that rotates in conjunction with the rotation of the crankshaft 15, and a cam shaft. 18, a cam portion 18 a provided so as to rotate integrally with the shaft 18, a swing arm 20 that is periodically pressed by the cam portion 18 a, and a pivot portion 22 that serves as a swing fulcrum of the swing arm 20.

  Similarly, the valve operating mechanism 29 for the exhaust valve 9 includes a return spring 17 that urges the exhaust valve 9 in the closing direction (upward in FIG. 2), and a cam shaft 19 that rotates in conjunction with the rotation of the crankshaft 15. A cam portion 19a provided to rotate integrally with the cam shaft 19, a swing arm 21 periodically pressed by the cam portion 19a, and a pivot portion 22 serving as a swing fulcrum of the swing arm 20. ing.

  By the valve mechanisms 28 and 29 as described above, the intake valve 8 and the exhaust valve 9 are driven to open and close as follows. That is, when the camshafts 18 and 19 are rotated with the rotation of the crankshaft 15, the cam followers 20a and 21a that are rotatably provided at the substantially central portions of the swing arms 20 and 21 are periodically lowered by the cam portions 18a and 19a. While being pressed, the swing arms 20 and 21 swing and displace with the pivot portion 22 supporting one end thereof as a fulcrum. Accordingly, the other ends of the swing arms 20 and 21 press the intake and exhaust valves 8 and 9 downward against the urging force of the return springs 16 and 17, thereby opening the intake and exhaust valves 8 and 9. To do. The intake / exhaust valves 8 and 9 once opened are returned to the closed position again by the urging force of the return springs 16 and 17.

  The pivot portion 22 is supported by a known hydraulic lash adjuster 24, 25 (hereinafter abbreviated as “HLA”, which is an acronym for “Hydraulic Lash Adjuster”) that automatically adjusts the valve clearance to zero. Among them, the HLA 24 automatically adjusts the valve clearances of the second cylinder 2B and the third cylinder 2C on the center side in the cylinder row direction, and the HLA 25 is the first cylinder 2A and the first cylinders at both ends in the cylinder row direction. The valve clearance of the 4-cylinder 2D is automatically adjusted.

  The HLA 25 for the first cylinder 2A and the fourth cylinder 2D has a function of switching whether the intake / exhaust valves 8 and 9 are opened / closed or stopped depending on whether the engine is in a reduced cylinder operation or an all cylinder operation. That is, the HLA 25 opens and closes the intake and exhaust valves 8 and 9 of the first and fourth cylinders 2A and 2D during the entire cylinder operation of the engine, while the first and fourth cylinders 2A and 2D operate during the reduced cylinder operation of the engine. The intake / exhaust valves 8 and 9 are stopped in the closed state. For this reason, the HLA 25 has a valve stop mechanism 25a shown in FIG. 3 as a mechanism for stopping the opening / closing operation of the intake and exhaust valves 8, 9. On the other hand, the HLA 24 for the second cylinder 2B and the third cylinder 2C does not include the valve stop mechanism 25a and does not have a function of stopping the opening / closing operation of the intake and exhaust valves 8 and 9. Below, in order to distinguish these HLA24 and 25, the HLA25 provided with the valve stop mechanism 25a is especially called S-HLA25 (Abbreviation of Switchable-Hydraulic LashAdjuster).

  The valve stop mechanism 25a of the S-HLA 25 includes a bottomed outer cylinder 251 that accommodates the pivot portion 22 so as to be slidable in the axial direction, and two through-holes provided on the peripheral surface of the outer cylinder 251 so as to face each other. A pair of lock pins 252 capable of entering and exiting 251a and capable of switching the pivot portion 22 between a locked state and an unlocked state; a lock spring 253 that urges the lock pins 252 radially outward; and an inner bottom portion of the outer cylinder 251 And a lost motion spring 254 that presses and urges the pivot portion 22 above the outer cylinder 251.

  As shown in FIG. 3A, when the lock pin 252 is fitted in the through hole 251a of the outer cylinder 251, the pivot portion 22 is in a locked state in which it is fixed while protruding upward. In this locked state, as shown in FIG. 2, the top portion of the pivot portion 22 serves as the swing fulcrum of the swing arms 20 and 21, so that the cam portions 18a and 19a rotate the cam followers 20a and 21a as the cam shafts 18 and 19 rotate. When pressed downward, the intake / exhaust valves 8, 9 are displaced downward against the urging force of the return springs 16, 17, and the intake / exhaust valves 8, 9 are opened. Therefore, at the time of all cylinder operation in which all the four cylinders 2A to 2D are operated, the intake / exhaust valves 8 and 9 of the first and fourth cylinders 2A and 2D are opened and closed by the pivot portion 22 being locked. The

  To release the locked state as described above, the pair of lock pins 252 are pressed radially inward. Then, as shown in FIG. 3B, the pair of lock pins 252 move in a direction approaching each other (in the radial direction of the outer cylinder 251) against the tensile force of the lock spring 253. Thereby, the fitting between the lock pin 252 and the through hole 251a of the outer cylinder 251 is released, and the pivot portion 22 is in an unlocked state in which it can move in the axial direction.

  With the change to the unlocked state, the pivot portion 22 is pressed downward against the urging force of the lost motion spring 254, thereby realizing the valve stop state as shown in FIG. That is, the return springs 16 and 17 that urge the intake and exhaust valves 8 and 9 upward have a stronger urging force than the lost motion spring 254 that urges the pivot portion 22 upward. In the released state, when the cam portions 18a and 19a press the cam followers 20a and 21a downward as the cam shafts 18 and 19 rotate, the top portions of the intake and exhaust valves 8 and 9 become the swing fulcrum of the swing arms 20 and 21. The pivot portion 22 is displaced downward against the urging force of the lost motion spring 254. That is, the intake / exhaust valves 8 and 9 are maintained in a closed state. For this reason, during the reduced-cylinder operation in which the first and fourth cylinders 2A and 2D are deactivated, the intake and exhaust valves 8 and 9 of the first and fourth cylinders 2A and 2D are set by releasing the valve stop mechanism 25a. Is stopped and the intake and exhaust valves 8 and 9 are maintained in the closed state.

  The valve stop mechanism 25a is a hydraulic drive type, and the valve stop mechanism 25a, more specifically, the lock pin 252 of the valve stop mechanism 25a is driven by hydraulic pressure. The lock pin 252 enters and exits the through hole 251a according to the supplied hydraulic pressure, and the lock pin 252 and the through hole 251a of the outer cylinder 251 are fitted / released.

  As shown in FIG. 4, hydraulic oil is supplied from the oil pump 41 to the valve stop mechanism 25a. A solenoid valve 42 is provided in the oil path between the oil pump 41 and the valve stop mechanism 25a, and the solenoid valve 42 changes the hydraulic pressure supplied from the oil pump 41 to the valve stop mechanism 25a. Specifically, when the solenoid valve 42 is not energized, that is, when the solenoid valve 42 is OFF, the oil path between the oil pump 41 and the valve stop mechanism 25a is closed by the solenoid valve 42, and the lock pin 252 The outer cylinder 251 is fitted with the through hole 251a, the pivot portion 22 is locked, and the intake / exhaust valve is driven to open and close accordingly. On the other hand, when the solenoid valve 42 is energized, that is, when the solenoid valve 42 is ON, the oil passage between the oil pump 41 and the valve stop mechanism 25a is opened, and the lock pin 252 and the through hole 251a of the outer cylinder 251 Is released, the pivot portion 22 is unlocked, and the intake / exhaust valve is held closed.

  In the present embodiment, one valve stop mechanism solenoid valve 42 is provided for one cylinder, and a total of two valve stop mechanism solenoid valves 42 are provided. Then, one valve stop mechanism solenoid valve 42 supplies hydraulic pressure to the valve stop mechanism 25a provided in the intake valve 8 of the first cylinder 2A and the valve stop mechanism 25a provided in the exhaust valve 9 of the first cylinder 2A. The other valve stop mechanism solenoid valve 42 is connected to the valve stop mechanism 25a provided in the intake valve 8 of the fourth cylinder 2D and the valve stop mechanism 25a provided in the exhaust valve 9 of the fourth cylinder 2D. Change the hydraulic pressure to be supplied at the same time.

(3) Control system Next, an engine control system will be described. Each part of the engine of the present embodiment is comprehensively controlled by an ECU (engine control unit, control means) 50 shown in FIG. As is well known, the ECU 50 is a microprocessor including a CPU, a ROM, a RAM, and the like.

  The engine and the vehicle are provided with a plurality of sensors for detecting the state quantities of the respective parts, and information from each sensor is input to the ECU 50.

  For example, the cylinder block 3 is provided with a crank angle sensor SN1 that detects a rotation angle (crank angle) and a rotation speed of the crankshaft 15. The crank angle sensor SN1 outputs a pulse signal in accordance with the rotation of a crank plate (not shown) that rotates integrally with the crankshaft 15, and based on this pulse signal, the rotation angle and rotational speed of the crankshaft 15, that is, The engine speed is specified.

  The cylinder head 4 is provided with a cam angle sensor SN2. The cam angle sensor SN2 outputs a pulse signal according to the passage of the teeth of the signal plate that rotates integrally with the camshaft (18 or 19), and this signal and the pulse signal from the crank angle sensor SN1 On the basis of this, the cylinder discrimination information such as which cylinder is in which stroke is specified.

  The surge tank 32 in the intake passage 30 is provided with an intake air amount sensor SN3 that detects an intake air amount that is an air amount that passes through the surge tank 32 and is introduced into each cylinder 2A to 2D. An intake pressure sensor SN4 is provided for detecting the pressure.

  The vehicle is provided with an accelerator opening sensor SN5 that detects an opening degree of an accelerator pedal (accelerator opening degree) that is operated by a driver and that is not shown. Further, a water temperature sensor SN6 that detects the temperature of the cooling water that cools the engine body 1 is provided.

  The ECU 50 is electrically connected to the sensors SN1 to SN6 and the like, and various information (engine speed, cylinder information, intake air amount, intake pressure, accelerator opening, Acquire cooling water temperature, etc.).

  And ECU50 controls each part of an engine, performing various determination, a calculation, etc. based on the input signal from each said sensor SN1-SN6. The ECU 50 is electrically connected to the injector 12, spark plug 13, throttle actuator 34b (throttle valve 34a), valve stop mechanism solenoid valve 42 (valve stop mechanism 25a), and the like, based on the result of the above calculation and the like. The control signals for driving are output to these devices. In this embodiment, there are a total of four sets of injectors 12 and spark plugs 13 at a rate of one set per cylinder. In FIG. 5, the injectors 12 and the spark plugs 13 are each represented by one block. . Further, one valve stop mechanism solenoid valve 42 is provided for each of the valve stop mechanism 25a of the first cylinder 2A and the valve stop mechanism 25a of the fourth cylinder 2D, for a total of two valve stop mechanisms. There is a solenoid valve 42 for use, and this is shown in one block in FIG.

  More specific functions of the ECU 50 will be described. The ECU 50 includes, as functional elements, an operation region determination unit 51, a preparation control execution determination unit 52, a reduced cylinder operation start determination unit 53, and a combustion control unit 54.

  The combustion control unit 54 controls the combustion state of each of the cylinders 2A to 2D, and includes a valve stop mechanism control unit 54a, a throttle valve control unit 54b, and an ignition timing control unit 54c.

  The operation area determination unit 51 determines whether the engine is operated in the reduced cylinder operation area or the all cylinder operation area.

  The reduced-cylinder operation area is set to an area where fuel consumption can be reduced and fuel consumption performance can be improved by performing reduced-cylinder operation rather than performing full-cylinder operation. Is set to

  In the present embodiment, for the cooling water temperature, the engine load, and the engine speed, a reduced-cylinder operation region in which reduced-cylinder operation is performed and an all-cylinder operation region in which all-cylinder operation is performed are set in advance, and an operation region determination unit 51, and the operation region determination unit 51 stores the engine load, the engine speed, and the coolant temperature specified from the detected values of the accelerator opening sensor SN5, the crank angle sensor SN1, and the water temperature sensor SN6 in these regions. Which is included is determined.

  Specifically, the reduced-cylinder operation region is set to an operation region in which the coolant temperature is equal to or higher than a predetermined temperature, and the engine speed and the engine load are in the ranges indicated by A1 in FIG. In the area A1, an area where the engine speed is N_min or more and N_max or less and the engine load is Tq_min or more and Tq_max or less is set. The all-cylinder operation region is set to the remaining operation region, that is, a region in which the coolant temperature is equal to or lower than the predetermined temperature, and the engine speed and the engine load are in a range indicated by A2 in FIG. In the present embodiment, Tq_min is set to 0, but is not limited to this, and may be set to a value larger than 0.

  Hereinafter, a case where the cooling water temperature is equal to or higher than a predetermined temperature and the reduced cylinder operation region and the all cylinder operation region are defined by the engine speed and the engine load will be described, and the region A1 is simply referred to as the reduced cylinder operation region A1. The area A2 is simply referred to as an all-cylinder operation area A2.

  Here, in the reduced-cylinder operation, since the number of operating cylinders, which are cylinders that perform output after combustion, is reduced, the output per cylinder of the operating cylinders (second and third cylinders 2B, 2C) is all cylinders. It needs to be larger than when driving. Therefore, in the present embodiment, the engine torque is secured by increasing the intake air amount of each of the cylinders 2A to 2D during the reduced cylinder operation than during the all cylinder operation. However, since there is a delay in the change in the intake air amount, when switching from all-cylinder operation to reduced-cylinder operation, combustion in the idle cylinders (first and fourth cylinders 2A and 2D) is immediately stopped and reduced-cylinder operation is started. In this case, the intake amount of the operating cylinders (second and third cylinders 2B and 2C) is insufficient, the engine torque is reduced, and a torque shock occurs.

  Therefore, in the present embodiment, the intake air amount of these cylinders 2A to 2D is set to the intake air amount at the time of the reduced cylinder operation in the state where the combustion is performed in all the cylinders 2A to 2D before the reduced cylinder operation is started. Increase. However, if combustion is performed in all the cylinders 2A to 2D with the intake air amount increased in this way, the engine torque will increase this time.

  Correspondingly, in this embodiment, before starting the reduced-cylinder operation, while increasing the intake amount of these cylinders 2A to 2D while performing combustion in each of the cylinders 2A to 2D, the engine accompanying the increase of the intake amount Preparation control is performed to retard the ignition timing of the cylinders 2A to 2D so as to cancel the increase in torque.

  When the engine is operating in the reduced-cylinder operation region A1, the preparation control execution determination unit 52 determines whether or not to start the preparation control until the reduced-cylinder operation is started, and the preparation being performed. It is determined whether to stop the control and return to the normal all-cylinder operation. A specific determination procedure of the preparation control execution determination unit 52 will be described later.

  The reduced-cylinder operation start determination unit 53 determines whether to end the preparation control and start the reduced-cylinder operation when the engine is operated in the reduced-cylinder operation region A1. The reduced-cylinder operation start determination unit 53 determines to end the preparation control and start the reduced-cylinder operation when the intake air amount of each of the cylinders 2A to 2D increases to the intake air amount during the reduced-cylinder operation with the execution of the preparation control. .

  The valve stop mechanism control unit 54a controls the valve stop mechanism solenoid valve 42 to control the hydraulic pressure supplied to the valve stop mechanism 25a of the S-HLA 25, that is, the intake and exhaust valves 8, 9 of the first and fourth cylinders 2A, 2D. The opening / closing operation is changed.

  The valve stop mechanism control unit 54a allows the intake / exhaust valves 8 and 9 of all the cylinders 2A to 2D to be opened and closed while the solenoid valve 42 is in an OFF state when the engine is operating in all cylinders. When the cylinder is operated, the solenoid valve 42 for the valve stop mechanism is turned on to hold the intake and exhaust valves 8 and 9 of the deactivated cylinders (first and fourth cylinders 2A and 2D) closed.

  The throttle valve control unit 54b controls the opening of the throttle valve 34a, that is, the intake air amount of each of the cylinders 2A to 2D. The ignition timing control unit 54c controls the ignition timing of the driven spark plug 13. Details of the control contents of the throttle valve control unit 54b and the ignition timing control unit 54c will be described below.

(4) Control contents of throttle valve control unit and ignition timing control unit (4-1) Basic control First, throttle valve control unit 54b and ignition timing during normal all-cylinder operation and reduced-cylinder operation other than during the preparation control. The contents of control of the control unit 54c will be described.

  The throttle valve control unit 54b sets a target intake air amount that is a target value of the intake air amount in accordance with operating conditions, and controls the opening of the throttle valve 34a so that the intake air amount of each cylinder 2A to 2D becomes the target intake air amount. decide. Then, the throttle valve control unit 54b instructs the throttle actuator 34b so that the opening degree of the throttle valve 34a becomes the determined opening degree.

  In the present embodiment, the throttle valve control unit 54b corrects the basic opening degree set in advance according to the operating condition according to the deviation between the target intake air amount and the actual intake air amount, so that the final throttle valve 34a can be operated. Determine the opening. Note that the actual intake air amount is estimated based on the engine speed, detection values of the intake air amount sensor SN3 and the intake pressure sensor SN4, and the like.

  Specifically, in the throttle valve control unit 54b, a preset target intake air amount is stored as a map of the engine load and the engine speed, and the preset basic opening of the throttle valve 34a is set in the engine load. And the engine speed map. These maps are prepared for all-cylinder operation and reduced-cylinder operation. During all-cylinder operation, the target intake air amount and basic opening are extracted from the map for all-cylinder operation. The target intake air amount and the basic opening are extracted from the map for reduced-cylinder operation.

  Here, in the present embodiment, as described above, the intake air amount of each of the cylinders 2A to 2D in the reduced-cylinder operation is increased more than that in the all-cylinder operation, and the target intake air amount map has the same engine load and engine rotation. The target intake air amount is larger during reduced-cylinder operation than during full-cylinder operation, and the basic opening map shows the same engine load and engine speed during reduced-cylinder operation. Is set so that the basic opening is larger (open side) than during all cylinder operation.

  The ignition timing control unit 54c determines the ignition timing according to the operating conditions and issues an instruction to the spark plug 13. Specifically, the ignition timing control unit 54c stores a map of the ignition timing preset for the engine speed and the engine load, and the ignition timing control unit 54c uses the map to determine the engine speed and the engine load. The ignition timing corresponding to the load is extracted, and the extracted ignition timing is corrected based on the detected value of the intake pressure sensor SN4 and the like to determine the final ignition timing. Two types of maps for the ignition timing are prepared for reduced-cylinder operation and for all-cylinder operation, and a map corresponding to the operation is used.

(4-2) Preparation Control Preparation control will be described.

  As described above, the preparation control increases the intake air amount of each of the cylinders 2A to 2D and retards the ignition timing of these cylinders 2A to 2D so as to cancel the increase of the engine torque accompanying the increase of the intake air amount. In this preparation control, the throttle valve control unit 54b opens the throttle valve 34a so that the intake air amount of each of the cylinders 2A to 2D becomes the intake air amount during the reduced-cylinder operation. Change to open side rather than degree. The ignition timing control unit 54c changes the ignition timing to a timing retarded from the ignition timing during normal all-cylinder operation.

  In the present embodiment, the throttle valve control unit 54b performs the same control as the control during the reduced-cylinder operation described in (4-1) as the preparation control, and during the preparation control, the target intake air amount is set. The target intake air amount for the reduced cylinder operation is set, and the basic opening of the throttle valve 34a is set as the opening for the reduced cylinder operation, and the opening of the throttle valve 34a at which the target intake air amount during the reduced cylinder operation is realized is determined. Thus, an instruction is issued to the throttle actuator 34b so that the determined opening degree is realized.

  Further, the ignition timing control unit 54c calculates how much the actual intake air amount has increased with respect to the intake air amount during normal all-cylinder operation (target intake air amount for all-cylinder operation), and increases the intake air amount. The retard amount corresponding to the amount, specifically, the increase amount of the engine torque corresponding to the increase amount of the intake air amount is calculated. In the present embodiment, the ignition timing control unit 54c stores a map of intake air amount increase and retard amount preset for each operating condition (engine speed, engine load, etc.). Then, the retard amount corresponding to the operating condition and the calculated increase amount of the intake air amount is extracted. Then, the ignition timing control unit 54c determines a timing delayed by the determined delay amount from the ignition timing during normal all-cylinder operation as an ignition timing for preparation control.

(5) Determination procedure of the preparation control execution determination unit Whether to start the preparation control by the preparation control execution determination unit 52 and whether to stop the preparation control in progress and return to normal all-cylinder operation The determination procedure will be described with reference to the flowchart of FIG.

  The preparation control execution determination unit 52 functionally includes a reduced-cylinder operation duration estimation unit 52a, a fuel consumption improvement rate calculation unit 52b, a fuel consumption improvement amount calculation unit 52c, a fuel consumption deterioration amount calculation unit 52d, and a final fuel consumption improvement amount. And a calculation unit 52e.

(5-1) Reduced-cylinder operation duration estimation unit The reduced-cylinder operation duration estimation unit 52a is the time from the current time (time at the time of estimation calculation) to the return to the all-cylinder operation region A2, that is, the engine, A reduced-cylinder operation continuation time tr that is a time that is considered to be continuously operated in the reduced-cylinder operation region A1 is estimated.

  In the present embodiment, the reduced-cylinder operation duration estimation unit 52a estimates the reduced-cylinder operation duration based on the engine speed and the engine load (engine torque), respectively (steps S1 and S2). The shorter time tr is determined as the final reduced cylinder operation continuation time tr (step S3).

  First, the procedure for estimating the reduced-cylinder operation duration based on the engine speed will be described.

  In the present embodiment, it is assumed that the amount of change in the current engine speed (hereinafter, referred to as the current engine speed as appropriate) is kept constant until it deviates from the reduced-cylinder operating area A1 and returns to the all-cylinder operating area A2. Based on this, the reduced cylinder operation duration time tr_N is estimated, and when the engine speed continues to change with the current amount of change, the time when the engine speed deviates from the reduced cylinder operation area A1 is estimated as the reduced cylinder operation duration time tr_N. To do. That is, when the engine speed is currently increasing, the time when the engine speed exceeds the upper limit speed N_max of the reduced cylinder operation region A1, and when the engine speed is not currently increasing, the engine speed is decreased. The time exceeding the lower limit rotation speed N_min in the cylinder operation area A1 is estimated as the reduced cylinder operation duration time tr_N on the engine rotation speed side (step S1).

  Specifically, the reduced-cylinder operation duration estimation unit 52a determines whether the engine speed is increasing or decreasing (whether the change amount is greater than 0). When the engine speed is increasing (when the amount of change is greater than 0), the limit speed N_L used to estimate the reduced cylinder operation duration time tr_N is set to the upper limit speed N_max. On the other hand, when the engine speed is decreasing (when the change amount is 0 or less), the limit engine speed N_L used for estimating the reduced cylinder operation duration time tr_N is set to the lower limit engine speed N_min. Then, based on the limit engine speed N_L, the current engine speed Ni, and the change amount ΔNi of the current engine speed, the reduced cylinder operation duration time tr_N is calculated by the following equation (1).

tr_N = | N_L-Ni | / | ΔNi | (1)
Here, in the present embodiment, the engine speed change amount ΔNi is calculated from the vehicle acceleration α, the vehicle acceleration is α [m / s2], and the current gear ratio (including the final reduction ratio). Is the GR, the tire radius is R [m], and the circumferential ratio is π, the change amount ΔNi [rpm] of the engine speed is calculated by the following equation (2), and the calculated value is expressed by the equation (1). Applicable.

ΔNi = α × 60 × GR / (2 × π × R) (2)
However, when the acceleration α is 0 or when the gear is not engaged (when power transmission is not performed between the engine and the wheel), the engine is not used based on the engine speed without using the equation (2). The amount of change ΔNi in the rotational speed is calculated and applied to equation (1).

  Note that the acceleration α of the vehicle is specified from a detection value of a vehicle speed sensor (not shown) that detects a vehicle speed provided in the vehicle.

  Next, a procedure for estimating the reduced-cylinder operation duration based on the engine load will be described.

  In the present embodiment, as in the case of the engine speed, the engine load changes with the current amount of change based on the assumption that the current amount of change of the engine load is kept constant until it deviates from the reduced-cylinder operation region A1. If this is continued, the time during which the engine load deviates from the reduced cylinder operation region A1 is estimated as the reduced cylinder operation duration time tr_Tq. That is, when the engine load is increasing, the engine load exceeds the upper limit load Tq_max in the reduced cylinder operation region A1, and when the engine load is not increased, the engine load is the lower limit load Tq_min in the reduced cylinder operation region A1. Is estimated as the engine load side reduced cylinder operation continuation time tr_Tq (step S2).

  Specifically, the reduced-cylinder operation duration estimation unit 52a determines whether the engine load is increasing or decreasing (whether the change amount is greater than 0). When the engine load is increasing (when the change amount is greater than 0), the limit load Tq_L used for estimating the reduced cylinder operation duration time tr_Tq is set to the upper limit load Tq_max. On the other hand, when the engine load is decreasing (when the change amount is 0 or less), the limit load Tq_L used to estimate the reduced cylinder operation duration time tr is set as the lower limit load Tq_min. Based on this limit load Tq_L, the current engine load Tqi, and the current engine load change amount ΔTqi, the reduced cylinder operation duration time tr_Tq is calculated by the following equation (3). The engine load change amount ΔTq_L is calculated based on the change amount of the engine request load during a predetermined time by calculating the engine request load based on the accelerator pedal opening detected by the accelerator opening sensor SN5. can do.

tr_Tq = | Tq_L−Tqi | / | ΔTqi | (3)
Then, the reduced-cylinder operation continuation time estimation unit 52a finally determines a shorter time among the reduced-cylinder operation continuation time tr_N calculated based on the engine speed and the reduced-cylinder operation continuation time tr_Tq calculated based on the engine load. Decrease cylinder operation duration time tr is determined (step S3).

  As described above, the reduced-cylinder operation duration time tr is calculated based on the amount of change between the current engine speed and the engine load. Basically, the amount of change is large and the engine operation is in a transient state. In some cases, the calculation is short, and if the amount of change is small and the engine is operating normally, the calculation is long.

(5-2) Fuel Efficiency Improvement Rate Calculation Unit The fuel efficiency improvement rate calculation unit 52b is a reduction amount of the fuel consumption rate when the reduced cylinder operation is performed with respect to the fuel consumption rate (fuel consumption per unit time) when the all cylinder operation is performed. A fuel efficiency improvement rate EFt is calculated (step S4).

  In the present embodiment, the fuel efficiency improvement rate calculation unit 52b stores a fuel efficiency improvement rate EFt set in advance for the engine speed and the engine load as a map, and from this map, the current engine speed and the engine load are stored. The value corresponding to is extracted. Each value in this map is the difference in the fuel consumption rate when the all cylinder operation and the reduced cylinder operation are continued for a predetermined time with the engine speed and the engine load kept constant. Does not include the amount of change in the fuel consumption rate associated with switching between these operations. For example, as shown in FIG. 8, the fuel efficiency improvement rate EFt is set to be smaller as the engine load increases at a predetermined engine speed.

(5-3) Fuel Economy Improvement Amount Calculation Unit The fuel consumption improvement amount calculation unit 52c calculates a fuel consumption improvement amount that is a reduction amount of the fuel consumption obtained by performing the reduced-cylinder operation.

  In the present embodiment, the fuel consumption improvement amount calculation unit 52c is based on the reduced cylinder operation duration time tr estimated by the reduced cylinder operation duration estimation unit 52a and the fuel consumption improvement rate EFt calculated by the fuel consumption improvement rate calculation unit 52b. To calculate the fuel efficiency improvement amount IEF.

  Specifically, the fuel efficiency improvement amount calculation unit 52c calculates the fuel efficiency improvement amount IEF by the following equation (4) using the reduced-cylinder operation duration time tr and the fuel efficiency improvement rate EFt (step S5).

IEF = EFt × tr (4)
As described above, in the present embodiment, the fuel efficiency improvement amount IEF is calculated by assuming that the fuel efficiency is improved by the fuel efficiency improvement rate EFt on average during the reduced cylinder operation by performing the reduced cylinder operation.

  Here, as described above, the reduced-cylinder operation duration time tr is basically calculated as the change amount between the engine speed and the engine load is large and shorter in a transient state, and longer as the change amount is smaller and in a steady state. The Therefore, the fuel efficiency improvement amount IEF is calculated to be smaller as the change amount between the engine speed and the engine load is larger and in a transient state, and larger as the change amount is smaller and in a steady state.

  In the present embodiment, the fuel efficiency improvement rate EFt is calculated based on only the current engine speed and engine load. However, the engine speed change amount ΔNi and the engine load change amount ΔTqi are described. And the fuel efficiency improvement rate EFt immediately before exiting the reduced-cylinder operation based on the reduced-cylinder operation duration time tr, the fuel efficiency improvement rate EFt immediately before exiting the reduced-cylinder operation, and the current engine speed Alternatively, a value obtained by averaging the fuel efficiency improvement rate EFt calculated based on the engine load may be used. In this way, the fuel efficiency improvement amount IEF is calculated more accurately in consideration of the change in the fuel efficiency improvement rate EFt until it passes through the reduced-cylinder operation region.

(5-4) Fuel consumption deterioration amount calculation unit The fuel consumption deterioration amount calculation unit 52d calculates a fuel consumption deterioration amount DEF that is an increase amount of the fuel consumption amount due to the execution of the preparation control (step S6).

  In the present embodiment, as described above, preparation control is performed to retard the ignition timing when switching from all-cylinder operation to reduced-cylinder operation. Here, if the ignition timing is retarded, combustion efficiency deteriorates and fuel consumption deteriorates. The fuel consumption deterioration amount calculation unit 52d calculates the fuel consumption deterioration amount, that is, the fuel consumption increase amount that occurs with the retard of the ignition timing, and calculates this increase amount as the fuel consumption deterioration amount DEF.

  In the present embodiment, a map of the fuel consumption deterioration amount DEF preset for the engine speed and the engine load is stored in the fuel consumption deterioration amount calculation unit 52d, and the fuel consumption deterioration amount calculation unit 52d calculates the current fuel consumption deterioration amount calculation unit 52d from the current map. A value corresponding to the engine speed and the engine load is extracted.

  Here, the number of combustion cycles during the period in which the preparation control is performed increases as the engine speed increases and the time per combustion cycle decreases. Therefore, the fuel consumption deterioration amount DEF, which is an increase in fuel consumption caused by the execution of the preparation control, increases as the engine speed increases.

  Further, the amount of increase in the intake air amount during the preparation control increases as the engine load increases and the intake air amount increases. Accordingly, the retard amount of the ignition timing during the preparation control increases as the engine load increases. Therefore, the fuel efficiency deterioration amount DEF increases as the engine load increases.

  Correspondingly, in this embodiment, as shown in FIG. 9, the fuel consumption deterioration amount DEF is set such that its value increases as the engine speed and the engine load increase.

(5-5) Final fuel consumption improvement amount calculation unit The final fuel consumption improvement amount calculation unit 52e obtains the final fuel consumption obtained by switching from all-cylinder operation to reduced-cylinder operation in consideration of deterioration in fuel consumption associated with the execution of the preparation control. The final fuel consumption improvement amount IEF_f, which is an improvement amount of the fuel consumption, that is, a reduction amount of the fuel consumption amount is calculated (step S7).

  In the present embodiment, the final fuel consumption improvement amount calculation unit 52e obtains a value obtained by subtracting the fuel consumption deterioration amount DEF calculated by the fuel consumption deterioration amount calculation unit 52d from the fuel consumption improvement amount IEF calculated by the fuel consumption improvement amount calculation unit 52c. Calculated as the improvement amount IEF_f.

(5-6) Preparation Control Execution Determination Unit The preparation control execution determination unit 52 determines whether or not to perform preparation control toward the start of reduced-cylinder operation based on the final fuel efficiency improvement amount IEF_f, that is, preparation control has been started. If not, it is determined whether or not to start, and if preparation control is being performed, it is determined whether or not preparation control is to be continued. In the present embodiment, the final fuel efficiency improvement amount IEF_f is greater than 0, and the fuel efficiency improvement amount IEF exceeds the fuel efficiency deterioration amount DEF. That is, the reduction amount of the fuel consumption obtained by performing the reduced-cylinder operation is the execution of the preparation control. If the amount of increase in fuel consumption associated with the above is exceeded (if the determination in step S8 is YES), it is determined that the preparation control is started or continued (S9). On the other hand, the final fuel consumption improvement amount IEF_f is 0 or less, and the fuel consumption improvement amount IEF is less than the fuel consumption deterioration amount DEF. That is, the fuel consumption reduction amount obtained by performing the reduced-cylinder operation is associated with the execution of the preparation control. If it is less than the increase in fuel consumption (if the determination in step S8 is NO), the preparation control is not performed, that is, the normal all-cylinder operation is continued without starting the preparation control, or the preparation control is performed. Judgment is made to stop and return to normal all-cylinder operation.

  The preparation control execution determination unit 52 performs the above calculation and determination during the period until the reduced-cylinder operation is started in the reduced-cylinder operation region A1, that is, the operation region is changed from the all-cylinder operation region A2 to the reduced-cylinder operation region A1. The above-described calculation and determination are continuously performed during the period until the reduced-cylinder operation is started after switching to the return to the all-cylinder operation region A2. That is, the reduced-cylinder operation duration estimation unit 52a and the fuel efficiency improvement rate calculation unit 52b estimate (calculate) and update the reduced-cylinder operation duration tr and the fuel efficiency improvement rate EFt from time to time during the above period. The calculation unit 52c calculates the fuel efficiency improvement amount IEF based on these latest values. Further, the fuel consumption deterioration amount calculation unit 52d calculates and updates the fuel consumption deterioration amount DEF from time to time during the period. Then, the final fuel consumption improvement amount calculation unit 52e calculates the final fuel consumption improvement amount IEF_f based on the latest fuel consumption improvement amount IEF and the fuel consumption deterioration amount DEF, and the preparation control execution determination unit 52 determines the latest final fuel consumption improvement amount IEF_f. Based on the above, the above determination is made.

  Here, as described above, the fuel efficiency improvement amount IEF is calculated to be smaller as the change amount between the engine speed and the engine load is larger and in a transient state, and larger as the change amount is smaller and in a steady state. Therefore, in the present embodiment, the preparation control is not performed (stopped) when these changes are large and the engine operation is in a rapid transient state, and the preparation control is performed when the changes are small and the steady state. Is done.

(6) Flow of control in the reduced-cylinder operation region The overall flow of the above control performed in the reduced-cylinder operation region A1 is shown in the flowchart of FIG.

  First, in step S11, it is determined whether or not the engine is operated in the reduced cylinder operation region A1.

  When the determination in step S1 is NO and the operation is performed in the all-cylinder operation region A2, the process proceeds to step S12, and the normal all-cylinder operation is performed (continuation or return). On the other hand, when the determination in step S1 is YES and the vehicle is operating in the reduced cylinder operation region A1, the process proceeds to step S13.

  In step S13, the final fuel consumption improvement amount IEF_f is calculated by the above procedure (the procedure of steps S1 to S7 in FIG. 7).

  In step S14 following step S13, it is determined whether or not it is determined that the preparation control may be performed. If this determination is NO and it is determined that the preparation control is not performed because the final fuel efficiency improvement amount IEF_f is 0 or less, the process proceeds to step S12, and the normal all-cylinder operation is performed. That is, the normal all-cylinder operation is continued if the preparation control is not started, and the normal all-cylinder operation is returned if the preparation control is being performed. On the other hand, if the determination in step S14 is YES and it is determined that the preparation control is to be started or continued when the final fuel efficiency improvement amount IEF_f is greater than 0, the process proceeds to step S15.

  In step S15, the oil pump 41 increases the oil pressure of the oil passage between the oil pump 41 and the valve stop mechanism 25a, specifically, the oil passage between the oil pump 41 and the valve valve for stop valve solenoid. . This is because the intake / exhaust valves 8 and 9 of the deactivated cylinders (first and fourth cylinders 2A and 2D) are more reliably closed when the reduced cylinder operation is started. In this way, before starting the reduced cylinder operation, the oil pressure in the oil passage between the oil pump 41 and the valve stop mechanism solenoid valve 42 is increased, but the valve stop mechanism solenoid valve 42 is in the OFF state. At this time, the lock pin 252 of the valve stop mechanism 25a and the through hole 251a are maintained in a disengaged state, and the intake and exhaust valves 8 and 9 of the idle cylinders (first and fourth cylinders 2A and 2D) are maintained. Open / close drive.

  In step S16 following step S15, preparation control is performed. Specifically, if the preparatory control is not started, the preparatory control is started, and if the preparatory control is being performed, the preparatory control is continued. Specifically, the opening of the throttle valve 34a is changed to the opening at the time of the reduced cylinder operation, or the opening is maintained, and the intake air amount of each cylinder 2A to 2D is directed to the intake air amount at the time of the reduced cylinder operation. The ignition timing is retarded from the ignition timing during normal all-cylinder operation by a timing corresponding to the amount of increase in the intake air amount.

  In step S17, which is the next step after step S16, it is determined whether or not it has been determined that the reduced-cylinder operation is started when the intake amount becomes equal to or larger than the intake amount during the reduced-cylinder operation. If the determination in step S17 is YES and the intake amount is equal to or greater than the intake amount during the reduced cylinder operation and it is determined that the reduced cylinder operation is started, the process proceeds to step S18. On the other hand, if the determination in step S17 is NO and the intake air amount has not reached the intake air amount during the reduced cylinder operation and it is not determined that the reduced cylinder operation is started, the process returns to step S11.

  In step S18, reduced-cylinder operation is started. That is, when the intake air amount reaches the intake air amount during the reduced-cylinder operation, the reduced-cylinder operation is started, the ignition and fuel injection of the idle cylinders (first and fourth cylinders 2A, 2D) are stopped, and the solenoid for the valve stop mechanism The valve 42 is turned on, and the intake and exhaust valves 8 and 9 of the deactivated cylinders (first and fourth cylinders 2A and 2D) are held closed, and the operating cylinders (second and third cylinders 2B and 2C) are ignited. Control is switched to control during normal reduced-cylinder operation.

(7) Operation, etc. As described above, in the present embodiment, preparation control for retarding the ignition timing while increasing the intake air amount is performed before starting the reduced cylinder operation. Therefore, it is possible to avoid the occurrence of torque shock before and after switching from all-cylinder operation to reduced-cylinder operation.

  Here, if the ignition timing is retarded, the fuel consumption deteriorates. On the other hand, in the present embodiment, the final fuel consumption improvement amount IEF_f, which is a reduction in fuel consumption obtained by switching from the all-cylinder operation to the reduced-cylinder operation, taking into account the deterioration in fuel consumption accompanying the execution of this preparation control Even when the engine is operated in the reduced-cylinder operation region A1, the preparation control is executed toward the start of the reduced-cylinder operation only when the final fuel consumption improvement amount IEF_f is larger than 0. . Therefore, the fuel efficiency can be more reliably improved by performing the reduced-cylinder operation.

  In particular, the calculation of the final fuel efficiency improvement amount IEF_f and the determination of whether or not the final fuel efficiency improvement amount IEF_f is greater than 0 are continuously performed during the period until the reduced cylinder operation is started in the reduced cylinder operation region A1. Even during the execution of the control, when the final fuel efficiency improvement amount IEF_f becomes 0 or less, the preparation control is stopped and the normal all-cylinder operation is resumed, so that the fuel efficiency can be further improved.

  Further, the reduced-cylinder operation continuation time tr, which is a continuous operation time in the reduced-cylinder operation region A1, is estimated based on the engine operating state, and the estimated reduced-cylinder operation continuation time tr and the reduced-cylinder operation are performed. The fuel efficiency improvement amount IEF is estimated based on the fuel efficiency improvement rate EFt, which is an improvement amount of the fuel consumption rate obtained by doing this, and this fuel efficiency improvement amount IEF is an increase amount of the fuel consumption accompanying the execution of the preparation control. Since the final fuel efficiency improvement amount IEF_f is calculated based on the fuel efficiency deterioration amount DEF, these values can be estimated and calculated with higher accuracy.

(8) Modification In the above embodiment, the case where it is determined that the preparation control starts (continues) if the final fuel efficiency improvement amount IEF is greater than 0 is described. However, the determination reference amount is not limited to 0.

  In the above embodiment, the case where the intake air amount is changed by opening / closing the throttle valve 34a, that is, the case where the intake air amount is increased by changing the throttle valve 34a to the open side in the preparation control has been described. The means for changing (increasing) is not limited to this. For example, a variable intake valve timing mechanism that can change the opening / closing timing of the intake valve 8 may be provided, and thereby the intake amount may be changed (increased) by changing the opening / closing timing of the intake valve 8. Further, means capable of changing the valve lift of the intake valve 8 may be used, and the intake air amount may be changed (increased) by changing the valve lift.

  Moreover, although the said embodiment demonstrated the example which applied the control apparatus of this invention to the 4-cylinder gasoline engine, the form of the engine which can apply the control apparatus of this invention is not restricted to this. For example, a multi-cylinder engine other than four cylinders such as 6 cylinders or 8 cylinders may be targeted, and another type of internal combustion engine such as a diesel engine, an ethanol fuel engine, or an LPG engine may be targeted.

DESCRIPTION OF SYMBOLS 1 Engine main body 2A-2D Cylinder 13 Spark plug (ignition means)
25a Valve stop mechanism 50 ECU (control means)
52a Reduced cylinder operation duration estimation unit 52b Fuel consumption improvement rate calculation unit 52c Fuel consumption improvement amount calculation unit 52e Fuel consumption deterioration amount calculation unit 52e Final fuel consumption improvement amount calculation unit 54 Combustion control unit

Claims (2)

A plurality of cylinders having an intake valve and an exhaust valve are provided. In a predetermined all-cylinder operation region, all-cylinder operation is performed in which the air-fuel mixture is burned in all cylinders. A device for controlling an engine that stops combustion in a specific cylinder and performs reduced-cylinder operation,
Ignition means provided in each cylinder for igniting an air-fuel mixture in these cylinders;
An intake air amount changing means capable of changing an intake air amount that is an air amount sucked into each cylinder;
Control means for controlling each part of the engine including the ignition means and the intake air amount control means,
The control means includes
The final fuel consumption improvement amount that sequentially calculates the final fuel consumption improvement amount that is the amount of reduction in fuel consumption obtained by switching from all-cylinder operation to reduced-cylinder operation until the reduced-cylinder operation is started in the reduced-cylinder operation region. A calculation unit;
In the above-described reduced-cylinder operation region, when the calculated final fuel consumption improvement amount is equal to or greater than a preset reference amount, the intake air amount change means causes the intake air amount of each cylinder to be greater than the intake air amount during normal all-cylinder operation. The preparatory control is performed to increase the intake amount at the time of a large cylinder reduction operation and retard the ignition timing of each cylinder from the ignition timing at the time of normal all cylinder operation. A combustion control unit that starts the reduced cylinder operation when the intake amount becomes equal to or greater than the intake amount during the reduced cylinder operation,
When it is confirmed during the execution of the preparation control that the final fuel consumption improvement amount is less than the reference amount, the combustion control unit stops the preparation control and returns to normal all-cylinder operation,
The final fuel consumption improvement amount calculation unit
A reduced-cylinder operation duration estimation unit that estimates a reduced-cylinder operation duration that is the time until the operation region returns to the all-cylinder operation region;
Fuel efficiency improvement rate calculation that calculates the fuel efficiency improvement rate, which is the amount of reduction in fuel consumption per unit time during reduced cylinder operation, relative to the fuel consumption per unit time during all cylinder operation, based on the engine operating state And
A fuel consumption deterioration amount calculation unit that calculates a fuel consumption deterioration amount that is an increase amount of fuel consumption accompanying the execution of the preparation control,
An engine control device that calculates the final fuel consumption improvement amount based on the estimated reduced-cylinder operation duration, the calculated fuel consumption improvement rate, and the calculated fuel consumption deterioration amount. The engine control device according to claim 1,
The final fuel consumption improvement amount calculation unit calculates a value obtained by multiplying the fuel consumption improvement rate by the reduced-cylinder operation duration as a fuel consumption improvement amount, and calculates a value obtained by subtracting the fuel consumption deterioration amount from the fuel consumption improvement amount. An engine control device characterized in that it is calculated as an improvement amount.

Images