JP6998975B2 - Cylinder deactivation system - Google Patents

Description

The present invention relates to a cylinder deactivation system that deactivates an internal combustion engine.

As a device of this type, conventionally, a device is known in which fuel injection to a plurality of cylinders of an engine is sequentially stopped for each cylinder over time when a predetermined condition is satisfied when the vehicle is decelerated (for example). See Patent Document 1). In the apparatus described in Patent Document 1, fuel injection is sequentially stopped for each cylinder according to the firing order of each cylinder.

Japanese Unexamined Patent Application Publication No. 2003-49468

However, in a system in which a catalyst device for purifying exhaust gas is provided in each of a plurality of exhaust paths connected to the engine, fuel injection is sequentially stopped for each cylinder according to the firing order as in the device described in Patent Document 1. If it is configured, there is a possibility that a sufficient purification effect of the exhaust gas by the catalyst device cannot be obtained.

The cylinder deactivation system according to one aspect of the present invention includes an internal combustion engine having a plurality of cylinders including a plurality of first group cylinders belonging to the first group and a plurality of second group cylinders belonging to the second group, and a first group. Exhaust catalyst device interposed in the exhaust path and the exhaust path of the second group, a fuel supply unit that supplies fuel to a plurality of cylinders individually, and a plurality of fuels from the first mode that supplies fuel to a plurality of cylinders. When the command unit commands the mode switching to the second mode to stop the fuel supply to the cylinders and the command unit commands the mode switching from the first mode to the second mode, the fuel is supplied to a plurality of cylinders. It is provided with a control unit that controls the fuel supply unit so as to stop the fuel in stages. The control unit controls the fuel supply unit so as to sequentially stop the fuel supply to each of the plurality of first group cylinders and then sequentially stop the fuel supply to each of the plurality of second group cylinders.

According to the present invention, in a system in which a catalyst device is provided in each of a plurality of exhaust paths connected to an engine, even when the fuel supply is stopped in stages, the exhaust gas can be sufficiently purified by the catalyst device. be able to.

The figure which shows the arrangement of a plurality of cylinders in the engine to which the cylinder deactivation system which concerns on embodiment of this invention is applied. The figure which shows schematic the main part structure of the engine to which the cylinder deactivation system which concerns on embodiment of this invention is applied. The figure which shows an example of the operation as the comparative example of the Embodiment of this invention. The block diagram which shows the main part structure of the cylinder deactivation system which concerns on embodiment of this invention. The figure which shows an example of the characteristic set by the controller of FIG. The figure which shows an example of the delay time of the fuel cut of each cylinder calculated by the controller of FIG. The flowchart which shows an example of the process executed by the controller of FIG. The figure which shows an example of the operation of the cylinder deactivation system which concerns on embodiment of this invention. FIG. 5 shows another example of the characteristics set by the controller of FIG.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 9. The cylinder deactivation system according to the embodiment of the present invention is applied to an engine which is a spark ignition type internal combustion engine having a fuel cut function for stopping fuel supply to a plurality of cylinders when the vehicle is decelerated and traveling. The engine is, for example, a V-type 6-cylinder engine in which a plurality of cylinders are arranged in a V-shape in a side view to form a pair of front and rear banks, and there are four steps of intake, expansion, compression, and exhaust during an operation cycle. It is a 4-cycle engine that goes through. The engine may be an engine in which a pair of left and right banks are formed.

FIG. 1 is a diagram showing an arrangement of a plurality (six) cylinders # 1 to # 6 of the engine 1. The engine 1 has three cylinders # 1 to # 3 in the front bank (front bank) 1a and three cylinders # 4 to # 6 in the rear bank (rear bank) 1b. In the following, the three cylinders # 1 to # 3 belonging to the front bank 1a may be referred to as front bank cylinders, and the three cylinders # 4 to # 6 belonging to the bank 1b may be referred to as rear bank cylinders, respectively. Each cylinder # 1 to # 6 has the same configuration.

FIG. 2 is a diagram schematically showing a configuration of a main part of the engine 1. Note that FIG. 2 shows the configuration of any one of the cylinders # 1 to # 6. As shown in FIG. 2, the engine 1 is formed between a cylinder 3 formed in a cylinder block 2, a piston 4 slidably arranged inside the cylinder 3, and a piston 4 and a cylinder head 5. It also has a combustion chamber 6. The piston 4 is connected to the crankshaft 8 via a connecting rod 7, and the piston 4 reciprocates along the inner wall of the cylinder 3 to rotate the crankshaft 8.

The cylinder head 5 is provided with an intake port 11 and an exhaust port 12. The intake passage 13 communicates with the combustion chamber 6 via the intake port 11, while the exhaust passage 14 communicates with the combustion chamber 6 via the exhaust port 12. The intake port 11 is opened and closed by the intake valve 15, and the exhaust port 12 is opened and closed by the exhaust valve 16. A throttle valve 19 is provided in the intake passage 13 on the upstream side of the intake valve 15. The throttle valve 19 is composed of, for example, a butterfly valve, and the intake amount to the combustion chamber 6 is adjusted by the throttle valve 19. The intake valve 15 and the exhaust valve 16 are opened and closed by a valve operating mechanism 20.

A spark plug 17 and a direct injection injector 18 are mounted on the cylinder head 5 and the cylinder block 2 so as to face the combustion chamber 6, respectively. The spark plug 17 is arranged between the intake port 11 and the exhaust port 12, generates sparks by electric energy, and ignites the mixture of fuel and air in the combustion chamber 6. The injector 18 is arranged in the vicinity of the intake valve 15 and is driven by electric energy to inject fuel into the combustion chamber 6 diagonally downward. The injector 18 is not limited to this, and may be arranged in the vicinity of the spark plug 17.

The valve mechanism 20 has an intake camshaft 21 and an exhaust camshaft 22. The intake camshaft 21 integrally has an intake cam 21a corresponding to each cylinder (cylinder 3), and the exhaust camshaft 22 integrally has an exhaust cam 22a corresponding to each cylinder. The intake camshaft 21 and the exhaust camshaft 22 are connected to the crankshaft 8 via a timing belt (not shown), and make one rotation each time the crankshaft 8 makes two rotations. The intake valve 15 opens and closes at a predetermined timing according to the profile of the intake cam 21a via an intake rocker arm (not shown) by the rotation of the intake cam shaft 21. The exhaust valve 16 opens and closes at a predetermined timing according to the profile of the exhaust cam 22a via an exhaust rocker arm (not shown) by the rotation of the exhaust camshaft 22.

The output torque of the engine 1, that is, the torque due to the rotation of the crankshaft 8, is input to a transmission (not shown). The transmission is a stepped transmission in which the gear ratio can be changed stepwise according to a plurality of gears (for example, 6 gears). A continuously variable transmission whose gear ratio can be changed steplessly can also be used as a transmission. The rotation from the engine 1 is transmitted to the drive wheels after being changed by the transmission, whereby the vehicle travels.

As shown in FIG. 1, each exhaust passage 14 of the front bank cylinders # 1 to # 3 is connected to a common exhaust passage 141, and each exhaust passage 14 of the rear bank cylinders # 4 to # 6 is a common exhaust passage. Connected to 142. The exhaust passages on the front bank cylinders # 1 to # 3 and the rear bank cylinders # 4 to # 6 may be represented by 14A and 14B, respectively, in order to distinguish them from each other. The exhaust passages 141 and 142 are interposed with catalyst devices 23 and 24 for purifying the exhaust gas, respectively. The catalyst devices 23 and 24 are three-way catalysts having a function of removing / purifying HC, CO, and NOx contained in the exhaust gas by an oxidation / reduction action, and have the same configuration as each other. The purification efficiency of the catalyst devices 23 and 24 is high when the air-fuel ratio is the stoichiometric air-fuel ratio, and in the fuel excess state (rich state), the purification efficiency of HC and CO is low, and the air excess state (lean state). Then, the purification efficiency of NOx becomes low.

In such a configuration of the engine 1, when a predetermined fuel cut condition is satisfied and the fuel supply from the injector 18 is stopped, that is, the fuel is cut, if the fuel cuts of the plurality of cylinders # 1 to # 6 are performed at the same time, The engine output torque drops sharply and a shock occurs. Therefore, in order to reduce the shock, it is conceivable to cut the fuel one cylinder at a time in a predetermined order with the passage of time.

However, when the catalyst devices 23 and 24 are provided corresponding to the front bank cylinders # 1 to # 3 and the rear bank cylinders # 4 to # 6, as in the present embodiment, the fuel is cut one by one. , The burning time in the lean state may be long. As a result, the amount of oxygen stored increases, it becomes difficult to reduce NOx, and the emission may deteriorate. FIG. 3 is a diagram for explaining this point, and shows an example of the operation at the time of fuel cut. In the figure, the horizontal axis is time and the vertical axis is engine output torque. The characteristic f1 defined so that the torque gradually decreases with the passage of time is a characteristic (fuel cut characteristic) for defining the timing of fuel cut.

In FIG. 3, after the fuel cut is instructed, the fuel cut is executed step by step in the order of # 4 → # 1 → # 5 → # 2 → # 3 → # 6 (for example, the combustion order) starting from the time point t0. ing. For example, focusing on the rear bank cylinders # 4 to # 6 shown by the thick line in the figure, at time points t0 to t1, combustion is performed in two of the rear bank cylinders # 4 to # 6 # 5 and # 6 (two-cylinder combustion). Is performed, and at time points t1 to t2, combustion (one-cylinder combustion) is performed in one cylinder # 6. Therefore, the front bank cylinders # 4 to # 6 are in a lean state as a whole after the time point t0, and in particular, the degree of the lean state is large after the time point t1 when one cylinder combustion occurs, and the oxygen storage amount in the catalyst device 24 increases. do.

On the other hand, the time during which the lean state can be tolerated, that is, the time during which the catalyst device 24 can exert the NOx purification ability without the oxygen storage amount becoming saturated (lean allowable time Δta) is determined by the ability of the catalyst device 24. Therefore, if the actual lean state time (for example, one cylinder combustion time Δtb) is longer than the lean allowable time Δta, Nox is not purified and the emission deteriorates. In order to prevent such deterioration of emissions, the present embodiment constitutes a cylinder deactivation system as follows.

FIG. 4 is a block diagram showing a configuration of a main part of the cylinder deactivation system 100 according to the present embodiment. As shown in FIG. 4, the cylinder deactivation system 100 is configured around a controller 30 for engine control. The controller 30 is provided with a rotation speed sensor 31, an accelerator opening sensor 32, a vehicle speed sensor 33, a speed change sensor 34, an AF sensor 35, a torque sensor 36, and cylinders # 1 to # 6. A plurality of injectors 18 (only one is shown in FIG. 4) are connected.

The rotation speed sensor 31 is a sensor that detects the engine rotation speed. For example, the rotation speed sensor 31 is provided on the crankshaft 8 and includes a crank angle sensor that outputs a pulse signal as the crankshaft 8 rotates. The accelerator opening sensor 32 is provided on an accelerator pedal (not shown) of the vehicle, and detects an operation amount (accelerator opening) of the accelerator pedal. The vehicle speed sensor 33 detects the vehicle speed. The shift sensor 34 detects the current shift of the transmission. The AF sensor 35 is provided for each of the exhaust passages 14A and 14B, and detects the air-fuel ratio of the exhaust in each of the exhaust passages 14A and 14B. The torque sensor 36 is a sensor that detects the output torque of the engine 1 or a physical quantity that correlates with the output torque. For example, the torque sensor 36 is composed of an air flow sensor that detects the intake air amount of the engine 1, and is based on the detection value of the torque sensor 36. The output torque (estimated torque) of the engine 1 is obtained.

The controller 30 is composed of an electronic control unit (ECU), and includes a computer having a calculation unit such as a CPU, a storage unit such as a ROM and a RAM, and other peripheral circuits. The controller 30 has an operation mode command unit 301, a characteristic setting unit 302, an order determination unit 303, and an injector control unit 304 as a functional configuration.

The operation mode command unit 301 determines the success or failure of the predetermined combustion cut condition based on the signals from the rotation speed sensor 31, the accelerator opening sensor 32, and the vehicle speed sensor 33. Then, when it is determined that the fuel cut condition is satisfied, the operation mode is ordered to be switched from the normal mode in which the fuel cut is not performed for the cylinders # 1 to # 6 to the pause mode in which the fuel cut is performed. Specifically, the operation mode command unit 301 detects a state in which the accelerator opening is equal to or less than a predetermined value, the engine speed is equal to or higher than a predetermined value, and the vehicle speed is equal to or higher than a predetermined value when the fuel is not cut. If so, it is determined that the fuel cut condition is satisfied. For example, it is determined that the fuel cut condition is satisfied during deceleration running.

The characteristic setting unit 302 sets the fuel cut characteristic for defining the fuel cut timing according to the operating state of the vehicle. FIG. 5 is a diagram showing an example of fuel cut characteristics. The fuel cut characteristics are set according to the shift stage of the transmission, and all of them are set so that the torque gradually decreases with the passage of time. More specifically, the output torque detected by the torque sensor 36 is set as an initial value so that the amount of decrease in torque gradually decreases with the passage of time (so that the negative slope gradually decreases). .. For example, the characteristics f1 and f2 in FIG. 5 are characteristics at gears in which the engine speeds are different from each other at a predetermined rotation speed, and the characteristics f1 are characteristics at a speed lower than the characteristics f2. That is, the fuel cut characteristic is set so that the torque decrease becomes more gradual in order to reduce the shock due to the fuel cut as the gear shift becomes lower (the larger the gear ratio).

Although not shown, the fuel cut characteristic is set in consideration of not only the shift stage but also the engine speed. That is, when the gears are the same as each other, the lower the engine speed, the more gradual the torque decrease is set. When the operation mode command unit 301 commands the switching to the hibernation mode, the characteristic setting unit 302 sets the fuel cut characteristic based on the output torque detected by the torque sensor 36. In this case, for example, a characteristic corresponding to the current shift stage and the engine speed is selected from a plurality of fuel cut characteristics stored in advance in the storage unit of the controller 30 and set.

The order determination unit 303 determines the order of the cylinders for which fuel is cut. Specifically, the cylinder that injects fuel immediately after the pause mode is commanded is determined to be the cylinder that first cuts fuel (first cylinder). Next, the two cylinders belonging to the same group as the first cylinder are determined to be the cylinders that cut fuel second (second cylinder) and the cylinders that cut fuel third (third cylinder), respectively. Further, the three cylinders belonging to the group different from the first cylinder are determined to be the fourth, fifth and sixth fuel cut cylinders (fourth cylinder, fifth cylinder, sixth cylinder), respectively.

For example, when the first cylinder is the front bank cylinder # 1, the second cylinder and the third cylinder are the front bank cylinders # 2 and # 3, respectively, and the fourth cylinder, the fifth cylinder and the sixth cylinder are the rear bank cylinders, respectively. It becomes # 4, # 5, and # 6. On the other hand, when the first cylinder is, for example, the rear bank cylinder # 4, the second cylinder and the third cylinder are the rear bank cylinders # 5 and # 6, respectively, and the fourth cylinder, the fifth cylinder and the sixth cylinder are the front banks, respectively. The cylinders are # 1, # 2, and # 3. That is, the order determining unit 303 determines the order of the cylinders for fuel cutting so that the order of fuel cutting of the plurality of cylinders in the same group is continuous with each other.

When the operation mode command unit 301 commands the injector control unit 304 to switch to the hibernation mode, the injector control unit 304 outputs a control signal to the injectors 18 of each cylinder # 1 to # 6, respectively, and fuels the cylinders # 1 to # 6. Perform a cut. In this case, the injector control unit 304 first starts the fuel cut for the first cylinder and then the remaining cylinders (second cylinder to sixth cylinder) according to the fuel cut characteristic set by the characteristic setting unit 302. The time required to cut the fuel, that is, the delay time for the fuel cut is calculated for each cylinder. FIG. 6 is a diagram showing an example of the delay time calculated for the fuel cut characteristic f1. The delay time Δt1 for the first cylinder is 0.

As shown in FIG. 6, the injector control unit 304 assumes that the engine output torque decreases from the initial value T1 to T2, T3, T4, T5, T6 and 0 at equal intervals each time the fuel is cut one cylinder at a time. , Target points P1 to P6 corresponding to each torque T1 to T6 are set on the fuel cut characteristic f1. Further, the time from the time when the first cylinder cuts fuel (target point P1) to each target point P2 to P6 is calculated as the delay time Δt2, Δt3, Δ4, Δt5, Δt6 of the second cylinder to the sixth cylinder, respectively. .. Then, the elapsed time from the fuel cut of the first cylinder is counted, and when the elapsed time reaches the delay times Δt2 to Δt6, the fuel of the second cylinder to the sixth cylinder is sequentially cut.

Further, the injector control unit 304 outputs a control signal to the injector 18 so that the air-fuel ratio becomes the theoretical air-fuel ratio before the operation mode command unit 301 commands the switching to the hibernation mode, and controls the fuel injection amount. .. That is, AF feedback control is performed based on the signal from the AF sensor 35 . On the other hand, when the operation mode command unit 301 commands the switching to the hibernation mode, the AF feedback on the bank side where the fuel cut is started is stopped. For example, if the fuel cut on the front bank 1a side is started first, the AF feedback on the front bank 1a side is stopped, and the AF feedback on the rear bank 1b side continues. After that, when the fuel cut on the rear bank 1b side is started, the AF feedback on the rear bank 1b side also stops.

FIG. 7 is a flowchart showing an example of a process (fuel cut process) executed by the CPU of the controller 30 of FIG. The process shown in this flowchart is started, for example, when the engine 1 is operating in the normal mode. Then, it is repeated in a predetermined cycle until the switching to the hibernation mode is completed, that is, until the fuel cut for all the cylinders # 1 to # 6 is completed.

As shown in FIG. 7, first, in step S1, it is determined whether the flag is 0 or 1. In the initial state before the fuel cut condition is satisfied, the flag is 0. If the flag is determined to be 0 in step S1, the process proceeds to step S2, and if the flag is determined to be 1, the process proceeds to step S8. In step S2, the signals from the sensors 31 to 36 are read. Next, in step S3, it is determined whether or not the fuel cut condition is satisfied based on the signals from the sensors 31 to 33. If it is affirmed in step S3, the process proceeds to step S4, and if it is denied, the process ends. In this case, the fuel injection amount is controlled (feedback control) so that the air-fuel ratio detected by the AF sensor 35 becomes the stoichiometric air-fuel ratio. On the other hand, in step S4, the output torque detected by the torque sensor 36 is set as an initial value, and the fuel is based on the current shift stage detected by the shift stage sensor 34 and the engine rotation speed detected by the rotation speed sensor 31. Set the cut characteristics.

Next, in step S5, the order of fuel cut for the plurality of cylinders # 1 to # 6 (first cylinder to sixth cylinder) is determined. That is, the cylinder that injects fuel immediately after the fuel cut condition is satisfied is determined to be the first cylinder that cuts fuel first, and the remaining two cylinders in the same group as the first cylinder are determined to be the second cylinder and the third cylinder. Then, the three cylinders in the group different from the first cylinder are determined to be the fourth cylinder to the sixth cylinder. Next, in step S6, the delay times Δt2 to Δt6 from the start of the fuel cut of the first cylinder to the fuel cut of the second cylinder to the sixth cylinder are calculated according to the fuel cut characteristic set in step S4. do. Then, in step S7, the flag is set to 1.

Next, in step S8, it is determined whether or not the fuel cut delay time of any of the cylinders # 1 to # 6 has been reached. If affirmed in step S8, the process proceeds to step S9, and if denied, the process ends. In step S9, the fuel of the cylinder determined to have reached the delay time is cut, and the process is terminated. For the first cylinder, the delay time Δt1 is set to 0 (in other words, the delay time is not set), and the fuel is cut in step S9. For the second cylinder to the sixth cylinder, after the flag is set to 1, each time it is determined in step S8 that the delay times Δt2 to Δt6 are reached, the fuel is cut in step S9. When the fuel is cut, the AF feedback control for the bank to which the fuel-cut cylinder belongs is stopped.

FIG. 8 is a diagram showing an example of the operation of the cylinder deactivation system 100 according to the present embodiment. The characteristic f1 in the figure is the fuel cut characteristic set by the characteristic setting unit 302, and the characteristic of the stepped solid line is the characteristic of the torque decrease with the passage of time after the mode switching command to the hibernation mode. The characteristic of the stepped dotted line is, for example, the characteristic of the torque decrease when the fuel is cut according to the order of the ignition timings of the cylinders # 1 to # 6, as in FIG. That is, in the characteristic of the dotted line, the fuel is cut in the order of # 4, # 1, # 5, # 2, # 3, and # 6 at the target points P1 to P6.

In the example of FIG. 8, when the mode switching to the hibernation mode is instructed, the fuel cut of the front bank cylinder # 1 is first carried out at the target point P1. Next, the fuel cut of the remaining front bank cylinders # 2 and # 3 is carried out at the target points P2 and P3. After that, the fuel cuts of the rear bank cylinders # 4, # 5, and # 6 are sequentially carried out at the target points P4, P5, and P6. In FIG. 8, the timing of torque reduction is delayed from the fuel cut timing (target points P2 to P6), but this is due to the time lag of the operation of each cylinder # 2 to # 6 after the fuel cut. Is.

According to this embodiment, the fuel cuts of the plurality of cylinders # 1 to # 6 are continuously performed for each of the banks 1a and 1b. Therefore, the time Δtc from the start of the fuel cut of one cylinder (for example, # 1) of the front bank cylinders # 1 to # 3 to the end of the fuel cut of the three cylinders (# 1 to # 3), and . The time Δtd from the start of the fuel cut of one of the rear bank cylinders # 4 to # 6 (for example, # 4) to the end of the fuel cut of the three cylinders (# 4 to # 6) can be shortened. Therefore, the lean state time Δtc and Δtd of each of the banks 1a and 1b can be suppressed within the lean allowable time Δta of the catalyst devices 23 and 24, respectively, and deterioration of emissions can be reliably prevented.

According to this embodiment, the following effects can be obtained.
(1) The cylinder deactivation system 100 includes a plurality of front bank cylinders # 1 to # 3 belonging to the cylinder group of one bank 1a and a plurality of rear bank cylinders # 4 to # 6 belonging to the cylinder group of the other bank 1b. The engine 1 having a plurality of cylinders # 1 to # 6 including the exhaust catalyst devices 23 and 24 interposed in the exhaust passage 141 of the cylinder group of the bank 1a and the exhaust passage 142 of the cylinder group of the bank 1b, respectively. Injector 18 that supplies fuel to cylinders # 1 to # 6 individually, and pause to stop fuel supply to multiple cylinders # 1 to # 6 from the normal mode that supplies fuel to multiple cylinders # 1 to # 6. When the operation mode command unit 301 for commanding the mode switching to the mode and the operation mode command unit 301 command the mode switching from the normal mode to the hibernation mode, the fuel supply to the plurality of cylinders # 1 to # 6 is staged. It includes a controller 30 that controls the injector 18 so as to stop the engine (FIGS. 1 and 4). The controller 30 stops the fuel supply to the plurality of front bank cylinders # 1 to # 3, and then stops the fuel supply to the plurality of rear bank cylinders # 4 to # 6, or causes the controller 30 to stop the fuel supply to the plurality of rear bank cylinders # 4 to # 6. After stopping the fuel supply to 4 to # 6, the injector 18 is controlled so as to stop the fuel supply to the plurality of front bank cylinders # 1 to # 3.

When the fuel of a plurality of cylinders # 1 to # 6 is sequentially cut in this way, the front bank cylinders # 1 to # 3 and the rear bank cylinders # 4 to # 6 are fuel-cut in a continuous order, whereby the front bank is cut. The time Δtc from the start of the fuel cut of the 1 cylinder of 1a to the end of the fuel cut of the 3 cylinders and the time Δtd from the start of the fuel cut of the 1 cylinder of the rear bank 1b to the end of the fuel cut of the 3 cylinders are shortened. Therefore, the lean state time Δtc and Δtd of each bank 1a and 1b can be suppressed within the lean allowable time Δta of the catalyst devices 23 and 24, and the deterioration of emissions is surely suppressed while suppressing the shock due to the torque decrease at the time of fuel cut. Can be prevented.

(2) The cylinder deactivation system 100 further includes a characteristic setting unit 302 for setting a fuel cut characteristic in which the engine output torque gradually decreases with the passage of time (FIG. 4). The controller 30 controls the injector 18 so as to sequentially stop the fuel supply to the plurality of cylinders # 1 to # 6 according to the characteristic (for example, characteristic f1) set by the characteristic setting unit 302 (FIG. 8). As a result, the fuel cuts of the plurality of cylinders # 1 to # 6 can be stepwise executed at the optimum timing with less shock due to the torque decrease.

(3) The characteristic setting unit 302 sets a plurality of fuel cut characteristics f1 and f2 according to the shift stage (gear ratio) of the transmission configured to shift and output the rotation input from the engine 1. (Fig. 5). Although the magnitude of the shock at the time of fuel cut differs depending on the gear ratio, in the present embodiment, the fuel cut timing is determined by the characteristics according to the gear ratio, so that the fuel cut can be performed at the optimum timing.

(4) The cylinder deactivation system 100 further includes an AF sensor 35 that detects the air-fuel ratio of the exhaust gas. In the injector control unit 304, the air-fuel ratio detected by the AF sensor 35 becomes a predetermined air-fuel ratio (for example, the theoretical air-fuel ratio) before the operation mode command unit 301 commands the switching from the normal mode to the hibernation mode. When the injector 18 is controlled by the AF feedback control and the switching to the hibernation mode is instructed, the stop of the fuel supply to the plurality of front bank cylinders # 1 to # 3 is started, and the stop of the fuel supply is completed. Before this, the injector 18 is controlled so as to stop the AF feedback control for the plurality of front bank cylinders # 1 to # 3 and continue the AF feedback control for the plurality of rear bank cylinders # 4 to # 6. In this way, by stopping the AF feedback control for the bank where the fuel cut is started, it is possible to prevent the fuel injection amount from being excessively corrected to the rich side.

The fuel cut characteristic set by the characteristic setting unit 302 is not limited to the above-mentioned characteristics f1 and f2. FIG. 9 is a diagram showing an example of another fuel cut characteristic f3. In FIG. 9, the characteristic f4 showing the change in the output torque from the time when the accelerator pedal is turned off to the start of the fuel cut (time points t11 to t12), that is, the characteristic f4 immediately before the start of the characteristic f3 is also shown by a dotted line. .. There is a delay time (t11 to t12) from when the accelerator pedal is turned off until the fuel cut is started. The reason for this is that the decrease in the intake air amount of the engine 1 is delayed, that is, the intake air to the engine 1 is delayed with respect to the operation of the throttle valve 19, and the ignition timing is delayed in the ignition control. That is, it causes a delay in the retard angle shift process of the ignition timing. A plurality of characteristics f3 (solid lines) are set according to the shift stage and the engine speed, as described above, but FIG. 9 shows only a single characteristic corresponding to the above-mentioned characteristic f1.

As shown in FIG. 9, the output torque linearly decreases after the accelerator pedal is off (after the time point t11) (characteristic f4). The characteristic setting unit 302 calculates the inclination of the characteristic f4 based on the signal from the torque sensor 36, and sets the fuel cut characteristic f3 according to the calculated inclination of the characteristic f4. That is, the fuel cut characteristic f3 is set so that the characteristic has a constant inclination that matches the inclination of the characteristic f4. As a result, the torque decreases at a constant rate before and after the start of the fuel cut (before and after the time point t12), and the shock at the time of the fuel cut can be further reduced.

The above embodiment can be changed to various forms. Hereinafter, a modified example will be described. In the above embodiment, the V6 engine 1 having a pair of banks is used as the internal combustion engine, but if it has a plurality of cylinder groups (first group, second group), another engine such as a horizontally opposed engine or the like is used. An internal combustion engine can also be used. In the above embodiment, the front bank cylinders # 1 to # 3 and the rear bank cylinders # 4 to # 6 are each composed of three cylinders, but the number of first group cylinders and the number of second group cylinders are as described above. Not limited to.

In the above embodiment, the catalyst devices 23 and 24 are interposed in the exhaust passage 141 connected to the front bank 1a and the exhaust passage 142 connected to the rear bank 1b, respectively, but the exhaust passages of the first group and the second group The arrangement of the pair of catalyst devices is not limited to that described above as long as it is interposed in the exhaust passage. The exhaust catalyst device may have any configuration as long as it has an oxygen storage capacity and a reducing action. In the above embodiment, the direct injection type injectors 18 are used for each of the plurality of cylinders # 1 to # 6, but any configuration of the fuel supply unit can be used as long as the fuel is individually supplied to the plurality of cylinders. good.

In the above embodiment, the operation mode command unit 301 commands the mode switching from the normal mode (first mode) to the hibernation mode (second mode) based on the signals from the sensors 31 to 33, but the command unit The configuration of is not limited to this. When the fuel cut is ordered, the fuel supply to the plurality of first group cylinders (for example, front bank cylinders # 1 to # 3) is stopped, and then the plurality of second group cylinders (for example, rear bank cylinders # 4 to # 3) are stopped. As long as the fuel supply unit such as the injector 18 is controlled so as to stop the fuel supply to 6), the configuration of the controller 30 as the control unit may be anything. It is also possible to execute the fuel cut without setting the fuel cut characteristic by the characteristic setting unit 302 (setting unit). In the above embodiment, the air-fuel ratio of the exhaust gas is detected by the AF sensor 35, but the configuration of the air-fuel ratio detection unit may be anything.

The above description is merely an example, and the present invention is not limited to the above-described embodiments and modifications as long as the features of the present invention are not impaired. It is also possible to arbitrarily combine one or a plurality of the above-described embodiments and the modified examples, and it is also possible to combine the modified examples.

1 engine, 1a front bank, 1b rear bank, 18 injector, 23, 24 catalyst device, 30 controller, 100 cylinder deactivation system, 301 operation mode command unit, 302 characteristic setting unit, 303 order determination unit, 304 injector control unit

Claims (5)

An internal combustion engine having a plurality of cylinders including a plurality of first group cylinders belonging to the first group and a plurality of second group cylinders belonging to the second group.
An exhaust catalyst device interposed in the exhaust path of the first group and the exhaust path of the second group, respectively.
A fuel supply unit that individually supplies fuel to the plurality of cylinders,
A command unit that commands mode switching from the first mode for supplying fuel to the plurality of cylinders to the second mode for stopping the fuel supply to the plurality of cylinders.
When the mode switching from the first mode to the second mode is commanded by the command unit, a control unit that controls the fuel supply unit so as to gradually stop the fuel supply to the plurality of cylinders. Equipped with
The control unit controls the fuel supply unit so as to sequentially stop the fuel supply to each of the plurality of first group cylinders and then sequentially stop the fuel supply to each of the plurality of second group cylinders. Cylinder deactivation system featuring that. In the cylinder deactivation system according to claim 1,
Further provided with a setting unit for setting the characteristic that the output torque of the internal combustion engine gradually decreases with the passage of time.
The control unit is a cylinder deactivation system characterized in that the control unit controls the fuel supply unit so as to gradually stop the fuel supply to the plurality of cylinders according to the characteristics set by the setting unit. In the cylinder deactivation system according to claim 2,
The setting unit is a cylinder deactivation system characterized in that a plurality of the characteristics are set according to the gear ratio of a transmission configured to shift and output the rotation input from the internal combustion engine. In the cylinder deactivation system according to claim 2 or 3.
The setting unit is a cylinder deactivation system characterized in that the characteristics are set so that the output torque of the internal combustion engine decreases at a constant rate with the passage of time. In the cylinder deactivation system according to any one of claims 1 to 4.
Further equipped with an air-fuel ratio detection unit that detects the air-fuel ratio of exhaust gas,
Before the command unit commands switching from the first mode to the second mode, the control unit performs feedback control so that the air-fuel ratio detected by the air-fuel ratio detection unit becomes a predetermined air-fuel ratio. When the fuel supply unit is controlled and the command unit commands switching from the first mode to the second mode, the fuel supply to the plurality of first group cylinders is started to be stopped, and the fuel supply unit is started to stop. Before the stop of fuel supply to the plurality of first group cylinders is completed, the feedback control for the plurality of first group cylinders is stopped, and the feedback control for the plurality of second group cylinders is continued. A cylinder deactivation system characterized in that the fuel supply unit is controlled.

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