JP6327117B2 - Internal combustion engine control device - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine including a cylinder deactivation mechanism.

  A control device for an internal combustion engine having a cylinder deactivation mechanism is known (see, for example, Patent Document 1). As an operation mode of the internal combustion engine, when the cylinder deactivation mechanism is not activated, all cylinders are activated, and when the cylinder deactivation mechanism is activated, the deactivation target cylinder that is a part of the plurality of cylinders is deactivated. It becomes the cylinder rest operation to do. The cylinder deactivation mechanism deactivates the deactivation target cylinder by fixing the intake valve and the exhaust valve of the deactivation target cylinder to the closed state. Further, in Patent Document 1, during the cylinder deactivation operation, a fuel cut is performed on the cylinder to be deactivated, or even if a switching instruction is issued from the control device to the cylinder deactivation mechanism, the delay is not actually completed. It is stated that there is time. A fuel cut is a prohibition of fuel injection.

JP 2001-90564 A

As a state of the cylinder deactivation mechanism, a state where all of the plurality of cylinders are operated is referred to as a first state, and a state where the deactivation target cylinder is deactivated is referred to as a second state.
The present inventor relates to a control device for controlling an in-cylinder injection type internal combustion engine provided with a cylinder deactivation mechanism, in the case where the cylinder deactivation mechanism is set to the second state, that is, when the internal combustion engine is deactivated. The fuel cut is considered for the cylinder to be stopped. Further, the inventor performs the following return switching control as a control when the cylinder deactivation mechanism is switched from the second state to the first state, that is, when the internal combustion engine is returned from the non-cylinder operation to the all-cylinder operation. I am thinking.

  In the return switching control, when the cylinder deactivation mechanism is switched from the second state to the first state, an instruction to switch to the first state is output to the cylinder deactivation mechanism, and the cylinder deactivation mechanism actually enters the first state. The control is to request the release of the fuel cut to the functional part that performs the fuel cut for the cylinder to be stopped before the timing at which the switching is expected. Canceling the fuel cut means not performing the fuel cut, in other words, performing the fuel injection.

  The reason for this return switching control will be described. There is a delay between when the fuel cut is requested and when fuel injection is actually performed. For this reason, if the cylinder deactivation mechanism is actually in the first state and it is requested to cancel the fuel cut, fuel injection may not be performed in the first intake stroke of the deactivation target cylinder that has resumed operation. Increases sex. Then, the air (so-called fresh air) sucked into the cylinder to be deactivated flows as it is into the exhaust pipe, and the exhaust characteristics are deteriorated. Therefore, in the return switching control, the fuel cut is requested to be released before the cylinder deactivation mechanism actually enters the first state. For this reason, immediately after switching the cylinder deactivation mechanism from the second state to the first state, fuel injection can be performed at the first intake timing of the deactivation target cylinder that has resumed operation. Can be prevented.

  On the other hand, as an abnormality of the cylinder deactivation mechanism, there is an abnormality that remains in the second state (hereinafter, also referred to as an on-fixation abnormality). When this occurs, combustion occurs in a sealed cylinder, causing damage to the internal combustion engine.

  For this reason, for example, as a control device, if the cylinder deactivation mechanism remains in the second state even after outputting the switching instruction to the first state to the cylinder deactivation mechanism, it is determined that an on-fixation abnormality has occurred, It is conceivable to perform a process (hereinafter referred to as a combustion prevention process) for preventing combustion in the cylinder to be stopped.

  However, in general, it takes a certain amount of time to reliably determine that an abnormality has occurred in the control device. This is because if it is confirmed that the abnormal state has continued for a predetermined time, a method is adopted in which it is determined that the abnormality is actually occurring. For this reason, if it is determined that an on-fixing abnormality has occurred in the cylinder deactivation mechanism and then the combustion prevention process is performed, combustion in the sealed deactivation target cylinder cannot be prevented and damage to the internal combustion engine will occur. Cause it.

  Further, as a measure for preventing damage to the internal combustion engine when an on-fixation abnormality occurs in the cylinder deactivation mechanism, for example, a measure of performing combustion prevention processing when the cylinder deactivation mechanism is in the second state is conceivable. However, simply implementing this measure makes it difficult to improve the exhaust characteristics immediately after switching the cylinder deactivation mechanism from the second state to the first state when the cylinder deactivation mechanism is normal.

  This is because, after the cylinder deactivation mechanism is actually switched to the first state, a function part that performs the combustion prevention process is requested to cancel the combustion prevention process (that is, do not perform the combustion prevention process). Become. This is because, due to a delay from the time when the request is made until the combustion prevention process is not performed, combustion in the cylinder to be stopped after the restart of operation does not occur normally, leading to deterioration of exhaust characteristics. That is, the above-described return switching control becomes meaningless with respect to preventing deterioration of exhaust characteristics immediately after switching the cylinder deactivation mechanism from the second state to the first state.

  Accordingly, an object of the present invention is to achieve both prevention of damage to an internal combustion engine and prevention of deterioration of exhaust characteristics in a control device for controlling a direct injection internal combustion engine having a cylinder deactivation mechanism.

  The internal combustion engine to be controlled is an in-cylinder injection internal combustion engine and includes a cylinder deactivation mechanism. The cylinder deactivation mechanism includes a first state in which all of the plurality of cylinders in the internal combustion engine are operated, and an intake valve and an exhaust valve of a deactivation target cylinder, which are part of the cylinder, are fixed in a closed state to It switches to the 2nd state made to stop according to the switching instruction | indication given.

The internal combustion engine control device according to the first aspect of the present invention comprises fuel cut means, switching control means, possibility calculation means, combustion prevention means, and combustion prevention request means.
The fuel cut means performs the fuel cut on the cylinder to be deactivated when requested to perform the fuel cut on the cylinder to be deactivated, and stops performing the fuel cut on the cylinder to be deactivated when requested to cancel the fuel cut.

  The switching control means outputs an instruction for switching to the second state to the cylinder deactivation mechanism, and requests the fuel cut means to perform the fuel cut when the cylinder deactivation mechanism is set to the second state. When the cylinder deactivation mechanism is switched from the second state to the first state, the switching control means outputs a switching instruction to the first state to the cylinder deactivation mechanism, and the cylinder deactivation mechanism is switched to the first state. Prior to the expected timing, the fuel cut means is requested to cancel the fuel cut. The operation performed when the switching control unit switches the cylinder deactivation mechanism from the second state to the first state corresponds to the operation of the return switching control described above.

The possibility calculation means calculates the possibility that an on-fixation abnormality that is an abnormality that causes the cylinder deactivation mechanism to remain in the second state occurs.
The combustion prevention requesting means detects that combustion occurs inside the cylinder to be deactivated when the cylinder deactivation mechanism is in the second state and the possibility calculated by the possibility calculation means is greater than or equal to a predetermined value. The combustion prevention means for performing the combustion prevention process for preventing the combustion is requested to perform the combustion prevention process. And a combustion prevention means will implement a combustion prevention process, if implementation of a combustion prevention process is requested | required.

  In this internal combustion engine control device, when the possibility of occurrence of ON fixation in the cylinder deactivation mechanism is greater than or equal to a predetermined value, the combustion prevention requesting means becomes the combustion prevention means when the cylinder deactivation mechanism is in the second state. On the other hand, since the combustion prevention process is requested to be performed, the combustion prevention process is performed. For this reason, when an on-fixation abnormality occurs in the cylinder deactivation mechanism and the cylinder deactivation mechanism does not return to the first state from the second state even when receiving an instruction to switch to the first state, It is possible to reliably prevent combustion from occurring without delay. Therefore, damage to the internal combustion engine is surely prevented.

  Even if the cylinder deactivation mechanism is in the second state, the combustion prevention requesting means does not request the combustion prevention means to perform the combustion prevention process when the possibility of the on-fixation abnormality is less than a predetermined value. For this reason, in the case of the above-described problem caused by performing the combustion prevention process when the cylinder deactivation mechanism is in the second state, that is, when the normal cylinder deactivation mechanism is switched from the second state to the first state, It is possible to avoid a problem that exhaust characteristics are deteriorated due to a delay until the combustion prevention process is not performed.

  That is, in this internal combustion engine control device, the possibility of occurrence of an on-fixation abnormality in the cylinder deactivation mechanism is calculated, and the action of “requesting execution of combustion prevention processing when the cylinder deactivation mechanism is in the second state” is performed. It is carried out on condition that the calculated possibility is equal to or greater than a predetermined value. For this reason, when the normal cylinder deactivation mechanism is in the second state, it is possible to avoid performing the above treatment as much as possible. Therefore, it is possible to achieve both prevention of damage to the internal combustion engine and prevention of deterioration of exhaust characteristics.

  In addition, the code | symbol in the parenthesis described in the claim shows the correspondence with the specific means as described in embodiment mentioned later as one aspect, Comprising: The technical scope of this invention is limited is not.

It is a lineblock diagram showing the engine control system of an embodiment. It is explanatory drawing explaining the bank of an engine, and a cylinder deactivation mechanism. It is a flowchart showing the fuel cut control process with respect to a deactivation object cylinder. It is a flowchart showing the ignition cut control process with respect to a deactivation object cylinder. It is a time chart showing the contents of the cooperative control processing of the cylinder deactivation solenoid valve and the fuel cut. It is a flowchart showing the cooperative control process of the solenoid valve for cylinder deactivation and fuel cut. It is a flowchart showing an abnormality determination process. It is a time chart explaining the fail safe process with respect to an on-fixation abnormality. It is a time chart explaining the temporary 1st plan for preventing damage to an engine. It is a time chart explaining the fault of a temporary 1st plan. It is a time chart explaining the provisional 2nd plan for preventing damage to an engine. It is a time chart explaining the fault of a temporary 2nd plan. It is a flowchart showing a cylinder deactivation control process. It is a flowchart showing abnormality possibility calculation processing. It is explanatory drawing explaining a 1st data map. It is explanatory drawing explaining a 2nd data map.

Below, the engine control system of an embodiment is explained.
An engine control system 1 according to the embodiment shown in FIG. 1 is a system that controls an in-cylinder injection engine (internal combustion engine) 3 mounted on a vehicle (automobile).

  As shown in FIG. 2, the engine 3 is a V-type 6-cylinder engine having, for example, six cylinders 5-1 to 5-6. The engine 3 is provided with a first bank 7-1 provided with three cylinders 5-1, 5-2 and 5-3, and other three cylinders 5-4, 5-5 and 5-6. And a second bank 7-2. In the engine 3, air is supplied to the intake manifold 11-1 of the first bank 7-1 and the intake manifold 11-2 of the second bank 7-2 via the throttle 9. Then, air is supplied from the intake manifold 11-1 to each of the cylinders 5-1 to 5-3, and air is supplied from the intake manifold 11-2 to each of the cylinders 5-4 to 5-6. Further, the exhaust gas discharged from the cylinders 5-1 to 5-3 is discharged to the exhaust pipe 15 of the vehicle via the exhaust manifold 13-1 of the first bank 7-1. Similarly, the exhaust gas discharged from the cylinders 5-4 to 5-6 is discharged to the exhaust pipe 15 via the exhaust manifold 13-2 of the second bank 7-2. In the following description, when the cylinders 5-1 to 5-6 are not distinguished, “5” is used as a reference.

  As shown in FIG. 1, in the engine control system 1, fuel is supplied from a fuel distribution pipe (so-called fuel delivery pipe) 23 to an injector 21 as a fuel injection valve provided in each cylinder 5 of the engine 3. The fuel distribution pipe 23 functions as a reservoir that stores fuel pumped from a high-pressure pump (not shown). In FIG. 1, only one cylinder 5 is shown. In FIG. 1, reference numeral “25” is the intake valve of the cylinder 5, reference numeral “26” is the exhaust valve of the cylinder 5, and reference numeral “27” is the piston of the cylinder 5.

  The injector 21 is opened by being driven, and injects the fuel supplied from the fuel distribution pipe 23 into the cylinder 5 corresponding to itself. Each cylinder 5 is provided with a spark plug 29 that generates a spark in the cylinder 5.

Further, the engine 3 includes a cylinder deactivation mechanism 31. The cylinder deactivation mechanism 31 includes an electromagnetic valve (hereinafter also referred to as a cylinder deactivation electromagnetic valve) 33 and a state detection switch 35.
In the cylinder deactivation mechanism 31, when a drive signal is given to the electromagnetic valve 33 and the electromagnetic valve 33 is opened, the hydraulic oil pressurized by the oil pump 37 is supplied into the cylinder deactivation mechanism 31. As the hydraulic oil, for example, engine oil that is lubricating oil of the engine 3 is used. The cylinder deactivation mechanism 31 fixes the intake valve 25 and the exhaust valve 26 of the deactivation target cylinders, which are part of the six cylinders 5, to the closed state by the hydraulic pressure of the hydraulic oil supplied via the electromagnetic valve 33. . Then, the cylinder to be deactivated is in a sealed state and deactivated. In the present embodiment, as shown in FIG. 2, the cylinders to be deactivated are, for example, the three cylinders 5-1 to 5-3 of the first bank 7-1. For this reason, the cylinders 5-1 to 5-3 are also referred to as pause target cylinders 5-1 to 5-3.

  Further, the cylinder deactivation mechanism 31 closes without driving the electromagnetic valve 33, and when the hydraulic oil is not supplied from the oil pump 37, the intake valve 25 and the exhaust valve 26 of the cylinders 5-1 to 5-3. Without being fixed, the cylinders 5-1 to 5-3 are operated (that is, all the six cylinders 5 are operated). As a state of the cylinder deactivation mechanism 31, a state in which all of the cylinders 5 of the engine 3 are operated is referred to as a first state, and a state in which the deactivation target cylinders 5-1 to 5-3 are deactivated is referred to as a second state. The second state is a state in which the cylinder deactivation mechanism 31 is operating.

  The state detection switch 35 is a switch that detects whether the actual state of the cylinder deactivation mechanism 31 is the first state or the second state. The state detection switch 35 is turned on when hydraulic oil is supplied to the cylinder deactivation mechanism 31 via the electromagnetic valve 33 and the hydraulic pressure of the hydraulic oil becomes equal to or higher than a predetermined threshold value. The threshold value is a hydraulic pressure value that can fix the intake valve 25 and the exhaust valve 26 of the cylinders 5-1 to 5-3 in the closed state. In this example, the state detection switch 35 is turned on when the cylinder deactivation mechanism 31 is in the second state.

The engine control system 1 includes an electronic control device (hereinafter referred to as ECU) 39 as an internal combustion engine control device. ECU is an abbreviation for “Electronic Control Unit”.
The ECU 39 controls the injector 21 and spark plug 29 and the cylinder deactivation mechanism 31 of each cylinder 5. The ECU 39 includes a microcomputer 40 that controls the operation of the ECU 39. The microcomputer 40 includes a CPU 41 that executes a program, a ROM 42 that stores a program executed by the CPU 41, data that is referred to when the program is executed, a RAM 43 that stores a calculation result by the CPU 41, and data rewriting. Possible non-volatile memory 44.

  Although not shown, the ECU 39 includes an input circuit for causing the microcomputer 40 to input a signal from the outside of the ECU 39, an output circuit for outputting a signal to the outside of the ECU 39, and the like.

  The output circuit outputs a drive signal to the injector 21 according to a control signal from the microcomputer 40, outputs a drive signal to the energizing device 30 that energizes the spark plug 29, and an electromagnetic valve 33 of the cylinder deactivation mechanism 31. To output a drive signal.

  The input circuit causes the microcomputer 40 to input a signal from the state detection switch 35, a signal from the crank angle sensor 45 for detecting the crank angle of the engine 3, and other signals. Other signals include, for example, a signal from a water temperature sensor that detects the cooling water temperature of the engine 3, a signal from an intake air sensor that detects the intake air amount to the engine 3, and the amount of operation of the accelerator pedal by the driver of the vehicle There is a signal from an accelerator sensor for detecting the signal. Such an input signal to the microcomputer 40 is used for controlling the engine 3.

  Next, of the processes performed by the microcomputer 40, the contents of processes related to the control of the cylinder deactivation mechanism 31 will be mainly described. Note that the processing performed by the microcomputer 40 is actually realized by the CPU 41 executing a program in the ROM 42.

<Fuel cut control processing for cylinders to be deactivated>
For example, the microcomputer 40 executes the fuel cut control process of FIG. 3 at every timing that is a predetermined crank angle (for example, 90 ° CA) before the intake stroke start timing of the cylinders 5-1 to 5-3. The fuel cut control process of FIG. 3 is a process for performing a fuel cut on the cylinders 5-1 to 5-3 and canceling the fuel cut that has been performed. A fuel cut is a prohibition of fuel injection by the injector 21. “CA” is an abbreviation for crank angle.

  As shown in FIG. 3, in the fuel cut control process, the microcomputer 40 determines whether or not the fuel cut request flag is on in S110. The fact that the fuel cut request flag is on means that the fuel cut is requested for the cylinders 5-1 to 5-3, and that the fuel cut request flag is off means that the cylinders 5-1 to 5-1 are off. This means that the fuel cut cancellation for 5-3 is requested. The fuel cut request flag is, for example, a value “1” being on and a value “0” being off. The same applies to other flags described later.

  If the microcomputer 40 determines in S110 that the fuel cut request flag is ON, the microcomputer 40 proceeds to S120 and performs a setting for prohibiting fuel injection to the cylinders 5-1 to 5-3. Then, the microcomputer 40 ends the fuel cut control process. The process of S120 is a process of performing fuel cut for the cylinders 5-1 to 5-3.

  If the microcomputer 40 determines in S110 that the fuel cut request flag is not on (that is, it is off), the microcomputer 40 proceeds to S130 and permits fuel injection to the cylinders 5-1 to 5-3. Set up. Then, the microcomputer 40 ends the fuel cut control process. The process of S130 is a process of canceling the fuel cut for the cylinders 5-1 to 5-3.

<Ignition cut control processing for cylinders to be deactivated>
For example, the microcomputer 40 executes the ignition cut control process of FIG. 4 at each timing that is a predetermined crank angle (for example, 90 ° CA) before the compression stroke start timing of the cylinders 5-1 to 5-3. The ignition cut control process of FIG. 4 is a process for performing an ignition cut on the cylinders 5-1 to 5-3 and releasing the implemented ignition cut. The ignition cut is to prohibit ignition in the cylinder 5 by the spark plug 29.

  As shown in FIG. 4, in the ignition cut control process, the microcomputer 40 determines whether or not the ignition cut request flag is on in S150. When the ignition cut request flag is on, it means that the ignition cut is requested for the cylinders 5-1 to 5-3, and when the ignition cut request flag is off, the cylinders 5-1 to 5-1 are required. This means that the ignition cut for 5-3 is requested to be released.

  If the microcomputer 40 determines in S150 that the ignition cut request flag is on, the microcomputer 40 proceeds to S160 and performs a setting for prohibiting ignition to the cylinders 5-1 to 5-3. Then, the microcomputer 40 ends the ignition cut control process. The process of S160 is a process of performing ignition cut for the cylinders 5-1 to 5-3.

  If the microcomputer 40 determines in S150 that the ignition cut request flag is not on (that is, it is off), the microcomputer 40 proceeds to S170 and permits the ignition to the cylinders 5-1 to 5-3. I do. Then, the microcomputer 40 ends the ignition cut control process. The process of S170 is a process of canceling the ignition cut for the cylinders 5-1 to 5-3.

<Contents of cooperative control processing between solenoid valve for cylinder deactivation and fuel cut>
The microcomputer 40 pauses the cylinders 5-1 to 5-3 based on the required torque of the engine 3 calculated from the amount of operation of the accelerator pedal by the driver and the operating state of the engine 3 detected from the input signal. It is determined whether or not. If the microcomputer 40 determines that the cylinders 5-1 to 5-3 are to be deactivated, as shown in the first stage of FIG. If it is determined that 5-3 is not deactivated (that is, activated), the cylinder deactivation request flag is turned off. When the cylinder deactivation request flag is on, it means that deactivation of the cylinders 5-1 to 5-3 is requested. In other words, the cylinder deactivation mechanism 31 is requested to be in the second state. Means that On the other hand, when the cylinder deactivation request flag is off, it means that the operation of the cylinders 5-1 to 5-3 is requested. In other words, the cylinder deactivation mechanism 31 can be set to the first state. Means that it is required.

  As shown in FIG. 5, when the cylinder deactivation request flag is turned on, the microcomputer 40 sets a drive signal for the electromagnetic valve 33 (hereinafter referred to as an electromagnetic valve drive signal) in order to set the cylinder deactivation mechanism 31 to the second state. And the fuel cut request flag is also turned on. Note that turning on the solenoid valve drive signal means outputting the solenoid valve drive signal, which corresponds to outputting a switching instruction to the second state to the cylinder deactivation mechanism 31. Conversely, turning off the solenoid valve drive signal means stopping the output of the solenoid valve drive signal, which is equivalent to outputting an instruction for switching to the first state to the cylinder deactivation mechanism 31.

  As shown in FIG. 5, the microcomputer 40 turns on the solenoid valve drive signal and switches the cylinder deactivation mechanism 31 from the first state to the second state for the first time from the timing of turning on the solenoid valve drive signal. The timing ta at which T1 has elapsed is predicted as the timing at which the cylinder deactivation mechanism 31 switches to the second state. In FIG. 5 and other drawings to be described later and the following description, the “actual cylinder deactivation state” is an actual state of the cylinder deactivation mechanism 31. “The actual cylinder deactivation state is off” means that the actual state of the cylinder deactivation mechanism 31 is the first state, and “the actual cylinder deactivation state is on” means that the cylinder deactivation mechanism 31 is actually Is the second state.

  In the present embodiment, it is assumed that the cylinder deactivation mechanism 31 enters the second state when the electromagnetic valve 33 is opened. For this reason, the first time T1 is set to a valve opening drive delay time from when the solenoid valve drive signal is turned on until the solenoid valve 33 is opened. If it is necessary to consider the oil pressure increase delay time from when the electromagnetic valve 33 is opened until the oil pressure in the cylinder deactivation mechanism 31 becomes equal to or greater than the above threshold, the oil pressure increase delay time is also the first time. What is necessary is just to add to T1.

  Then, the microcomputer 40 turns on the fuel cut request flag only for the second time T2 before the timing ta at which the cylinder deactivation mechanism 31 is expected to actually switch to the second state. The second time T2 is the time from when the fuel cut request flag is turned on until the exhaust stroke of the cylinders 5-1 to 5-3 into which fuel has been injected before the fuel cut is started. In the embodiment, for example, the time is set to “90 ° CA + 720 ° CA”. Of that time, the time corresponding to 90 ° CA is the time from when it is determined in the fuel cut control process of FIG. 3 that the fuel cut request flag is on until when the fuel cut is actually started. The time for ° CA is the time for one cycle of the cylinder 5.

  By doing so, it is possible to prevent fuel from being injected after the cylinders 5-1 to 5-3 are sealed, and the burned gas in the cylinders 5-1 to 5-3 is discharged. Then, the cylinders 5-1 to 5-3 can be sealed.

  As shown in FIG. 5, when the cylinder deactivation request flag is turned off, the microcomputer 40 turns off the solenoid valve drive signal and also turns off the fuel cut request flag in order to set the cylinder deactivation mechanism 31 to the first state. To do.

  As shown in FIG. 5, the microcomputer 40 turns off the solenoid valve drive signal and switches the cylinder deactivation mechanism 31 from the second state to the first state for a third time from the timing of turning off the solenoid valve drive signal. The timing tb when T3 has elapsed is predicted as the timing when the cylinder deactivation mechanism 31 switches to the first state.

  In the present embodiment, it is assumed that the cylinder deactivation mechanism 31 enters the first state when the electromagnetic valve 33 is closed. For this reason, the third time T3 is set to a valve closing drive delay time from when the solenoid valve drive signal is turned off until the solenoid valve 33 is closed. In addition, when it is necessary to consider the oil pressure decrease delay time from when the electromagnetic valve 33 is closed until the oil pressure in the cylinder deactivation mechanism 31 becomes less than the threshold value, the oil pressure decrease delay time is also the third time. What is necessary is just to add to T3.

  Then, the microcomputer 40 turns off the fuel cut request flag 4th time T4 before the timing tb at which the cylinder deactivation mechanism 31 is expected to actually switch to the first state. In the fourth time T4, the cylinders 5-1 to 5-3 are referred to from the execution timing of the fuel cut control process (FIG. 3) that determines whether or not to perform fuel injection in the next intake stroke with reference to the fuel cut request flag. In this embodiment, it is set to the time of 90 ° CA.

  That is, when switching the cylinder deactivation mechanism 31 from the second state to the first state, the microcomputer 40 turns off the electromagnetic valve drive signal and predicts that the cylinder deactivation mechanism 31 actually switches to the first state. The fuel cut request flag is turned off only by the fourth time T4 before tb. The operation of the microcomputer 40 corresponds to the above-described return switching control operation.

  There is a delay between the time when the fuel cut request flag is turned off and the time when fuel is actually injected into the cylinders 5-1 to 5-3. For this reason, if the fuel cut request flag is turned off after the cylinder deactivation mechanism 31 is actually in the first state, fuel injection is performed in the first intake stroke of the cylinders 5-1 to 5-3 that have resumed operation. The possibility that it cannot be implemented increases. Then, the air (so-called fresh air) sucked into the cylinders 5-1 to 5-3 flows into the exhaust pipe 15 as it is, and the exhaust characteristics are deteriorated. Therefore, the fuel cut request flag is turned off before the microcomputer 40 and the cylinder deactivation mechanism 31 are actually in the first state. Therefore, immediately after the cylinder deactivation mechanism 31 is switched from the second state to the first state, fuel injection can be performed at the first intake timing of the cylinders 5-1 to 5-3 that have resumed operation, As a result, deterioration of exhaust characteristics can be prevented.

Next, cooperative control processing (hereinafter also simply referred to as cooperative control processing) between the cylinder deactivation electromagnetic valve 33 and the fuel cut will be described with reference to the flowchart of FIG.
The microcomputer 40 executes the cooperative control process of FIG. 6 at regular intervals when the engine 3 is in an operating state, for example. Further, the cooperative control process of FIG. 6 is executed in S520 of FIG.

  As shown in FIG. 6, when starting the cooperative control process, the microcomputer 40 determines whether or not to stop the cylinders 5-1 to 5-3 in S200, and determines a cylinder stop request according to the determination result. Set the flag on or off. As described above, when it is determined that the cylinders 5-1 to 5-3 are to be deactivated, the microcomputer 40 turns on the cylinder deactivation request flag and determines that the cylinders 5-1 to 5-3 are not to be deactivated. The cylinder deactivation request flag is turned off.

In the next S205, the microcomputer 40 determines whether or not the cylinder deactivation request flag set in S200 is on. If the cylinder deactivation request flag is on, the microcomputer 40 proceeds to S210.
In S210, the microcomputer 40 sets the larger one of the first time T1 and the second time T2 described above as the maximum delay.

  In the next S220, the microcomputer 40 sets a time obtained by subtracting the first time T1 from the maximum delay set in S210 as the first waiting time, and in the subsequent S230, the second time from the maximum delay set in S210. The time obtained by subtracting T2 is set as the second waiting time.

  The microcomputer 40 determines whether or not the first waiting time set in S220 has elapsed since the cylinder deactivation request flag was switched on in S240, and determines that the first waiting time has not elapsed. If so, the solenoid valve drive signal is turned off in S250. Then, the microcomputer 40 proceeds to S270. If it is determined in S240 that the first waiting time has elapsed, the microcomputer 40 turns on the electromagnetic valve drive signal in S260, and then proceeds to S270.

  In S270, the microcomputer 40 determines whether or not the second waiting time set in S230 has elapsed after switching on the cylinder deactivation request flag, and determines that the second waiting time has not elapsed. In S280, the fuel cut request flag is turned off. Then, the microcomputer 40 ends the cooperative control process. If it is determined in S270 that the second waiting time has elapsed, the microcomputer 40 turns on the fuel cut request flag in S290, and then ends the cooperative control process.

  That is, as shown in FIG. 5, when the cylinder deactivation request flag is turned on, the microcomputer 40 turns on the electromagnetic valve drive signal and the cylinder deactivation mechanism 31 is actually activated by the processing of S210 to S290. The fuel cut request flag is turned on only by the second time T2 before the timing ta at which it is expected to switch to the second state.

  In the example of FIG. 5, since the first time T1 is greater than the second time T2, the maximum delay set in S210 is the first time T1, the first waiting time set in S220 is 0, and S230 The second waiting time set at is “T1-T2”. Accordingly, when the microcomputer 40 turns the cylinder deactivation request flag from OFF to ON in S200, the microcomputer 40 immediately turns the solenoid valve drive signal ON in S260, and when “T1-T2” elapses thereafter, the fuel cut request is issued in S290. The flag will be turned on from off.

  Conversely, the second time T2 may be greater than the first time T1. In that case, the maximum delay set in S210 is the second time T2, the first waiting time set in S220 is “T2-T1”, and the second waiting time set in S230 is zero. Therefore, in this case, when the microcomputer 40 turns the cylinder deactivation request flag from OFF to ON in S200, the microcomputer 40 immediately turns on the fuel cut request flag in S290, and after that, when “T2-T1” has elapsed, S260 The electromagnetic valve drive signal is turned on from off.

On the other hand, if the microcomputer 40 determines in S205 that the cylinder deactivation request flag is not on (that is, it is off), the microcomputer 40 proceeds to S310.
In S310, the microcomputer 40 sets the larger one of the third time T3 and the fourth time T4 described above as the maximum delay.

  In the next S320, the microcomputer 40 sets a time obtained by subtracting the third time T3 from the maximum delay set in S310 as a third waiting time, and then in S330, the fourth time from the maximum delay set in S310. The time obtained by subtracting T4 is set as the fourth waiting time.

  In the next S340, the microcomputer 40 determines whether or not the third waiting time set in S320 has elapsed after switching the cylinder deactivation request flag to OFF, and determines that the third waiting time has not elapsed. If so, the electromagnetic valve drive signal is turned on in S350. Then, the microcomputer 40 proceeds to S370. If it is determined in S340 that the third waiting time has elapsed, the microcomputer 40 turns off the electromagnetic valve drive signal in S360, and then proceeds to S370.

  In S370, the microcomputer 40 determines whether or not the fourth waiting time set in S330 has elapsed since the cylinder deactivation request flag was switched on, and determines that the fourth waiting time has not elapsed. In S380, the fuel cut request flag is turned on. Then, the microcomputer 40 ends the cooperative control process. If it is determined in S370 that the fourth waiting time has elapsed, the microcomputer 40 turns off the fuel cut request flag in S390, and then ends the cooperative control process.

  That is, as shown in FIG. 5, when the cylinder deactivation request flag is turned off, the microcomputer 40 turns off the electromagnetic valve drive signal and the cylinder deactivation mechanism 31 is actually activated by the processing of S310 to S390. The fuel cut request flag is turned off only by the fourth time T2 before the timing tb at which it is expected to switch to the first state.

  In the example of FIG. 5, since the third time T3 is larger than the fourth time T4, the maximum delay set in S310 is the third time T3, the third waiting time set in S320 is 0, and S330 The fourth waiting time set at is “T3-T4”. Therefore, when the cylinder deactivation request flag is turned off from on in S200, the microcomputer 40 immediately turns off the solenoid valve drive signal in S360, and when "T3-T4" passes thereafter, the fuel cut request is made in S390. The flag will be turned off from on.

  Conversely, the fourth time T4 may be greater than the third time T3. In that case, the maximum delay set in S310 is the fourth time T4, the third waiting time set in S320 is “T4-T3”, and the fourth waiting time set in S330 is zero. Therefore, in this case, when the microcomputer 40 turns the cylinder deactivation request flag from on to off in S200, the microcomputer 40 immediately turns off the fuel cut request flag in S390, and when “T4-T3” elapses thereafter, S360 The electromagnetic valve drive signal is turned off from on.

  Further, for example, the first time T1 and the third time T3 can be configured to be variably set in accordance with a power supply voltage (for example, a vehicle battery voltage) serving as a power source of the electromagnetic valve drive signal. Further, for example, the hydraulic pressure of the hydraulic oil supplied to the cylinder deactivation mechanism 31 varies depending on the rotation speed of the engine 3 (hereinafter referred to as engine rotation speed), and the valve opening drive delay time and the valve closing drive delay time of the electromagnetic valve 33. The first time T1 and the third time T3 can be configured to be variably set according to the engine speed as long as it varies depending on the hydraulic oil pressure. The second time T2 and the fourth time T4 can be variably set according to the engine speed.

<Abnormality judgment processing>
The microcomputer 40 executes the abnormality determination process shown in FIG. 7 at regular time intervals, for example. The abnormality determination process in FIG. 7 is a process for determining an abnormality in the cylinder deactivation mechanism 31.

  As shown in FIG. 7, when starting the abnormality determination process, the microcomputer 40 calculates an estimated cylinder deactivation state in S410. The estimated cylinder deactivation state is an estimated state of the cylinder deactivation mechanism 31. “The estimated cylinder deactivation state is off” means that the estimated cylinder deactivation mechanism 31 is in the first state, and “the estimated cylinder deactivation state is on” means that the estimated cylinder deactivation mechanism 31 is in the state. Is in the second state. The microcomputer 40 turns off the solenoid valve drive signal after the first time T1 has elapsed since the solenoid valve drive signal was turned on (that is, at timing ta in FIG. 5). It is calculated that the estimated cylinder deactivation state is on during the period until the time elapses (that is, the timing tb in FIG. 5). During the other period, the microcomputer 40 calculates that the estimated cylinder deactivation state is off.

  In step S420, the microcomputer 40 determines whether or not the estimated cylinder deactivation state is off and the actual cylinder deactivation state is on. The microcomputer 40 determines an actual cylinder deactivation state based on a signal from the state detection switch 35.

  If the microcomputer 40 makes an affirmative determination (determined as YES) in S420 that the estimated cylinder deactivation state is off and the actual cylinder deactivation state is on, in S430, the temporary determination result is a temporary determination result. The determination result is set to “ON sticking abnormality”, and then the process proceeds to S470. The on-fixing abnormality is an abnormality that causes the cylinder deactivation mechanism 31 to remain in the second state. In this example, the electromagnetic valve 33 remains abnormal without being closed. The on-fixing abnormality of the cylinder deactivation mechanism 31 is simply referred to as on-fixing abnormality.

  If the microcomputer 40 makes a negative determination in S420, that is, if the estimated cylinder deactivation state is on or if the actual cylinder deactivation state is off, the microcomputer 40 proceeds to S440, where the estimated cylinder deactivation state is determined. It is determined whether it is on and the actual cylinder deactivation state is off.

  If the microcomputer 40 makes a positive determination in S440 that the estimated cylinder deactivation state is on and the actual cylinder deactivation state is off, in S450, the temporary determination result is set to “off sticking abnormality”. Thereafter, the process proceeds to S470. The off-fixing abnormality is an abnormality that causes the cylinder deactivation mechanism 31 to remain in the first state. In this example, the electromagnetic valve 33 does not open and remains closed.

  If the microcomputer 40 makes a negative determination in S440, that is, if the actual cylinder deactivation state and the estimated cylinder deactivation state are the same, in S460, the temporary determination result is set to “normal”. Thereafter, the process proceeds to S470.

  In S470, the microcomputer 40 determines whether or not the current temporary determination result is the same for a predetermined time T5 or more, and if the current temporary determination result is not the same for the predetermined time T5 or more, the abnormality determination process is ended as it is. . On the other hand, if the microcomputer 40 determines in S470 that the current tentative determination result is the same for the predetermined time T5 or more, the microcomputer 40 proceeds to S480 and determines the current tentative determination result as the determined determination result. Set as. After that, the microcomputer 40 ends the abnormality determination process.

  With this abnormality determination process, the microcomputer 40 sets the final determination result to “on-fixed abnormality” if the estimated cylinder deactivation state is off but the actual cylinder deactivation state is on for a predetermined time T5 or longer. It will be set. If the estimated cylinder deactivation state is on but the actual cylinder deactivation state is off for a predetermined time T5 or longer, the microcomputer 40 sets the determination result to “off sticking abnormality”. Become. If the estimated cylinder deactivation state and the actual cylinder deactivation state continue for the predetermined time T5 or longer, the microcomputer 40 sets the final determination result to “normal”. The predetermined time T5 is a time for reliably determining abnormality / normality.

<Fail-safe treatment for on-sticking abnormality>
As shown in FIG. 8, when an on-fixation abnormality occurs in the cylinder deactivation mechanism 31, even if the third time T3 has elapsed since the microcomputer 40 turned off the electromagnetic valve drive signal, the actual cylinder deactivation state is Stays on. For this reason, the microcomputer 40 sets the temporary determination result to “ON sticking abnormality” in S430 of FIG. 7 at the timing tb when the third time T3 has elapsed after the electromagnetic valve drive signal is turned off. Then, at the timing tc when the predetermined time T5 determined in S470 of FIG. 7 has elapsed from the timing tb, the microcomputer 40 sets the determination determination result to “ON-fixed abnormality” in S480 of FIG.

Further, when the determination result is “ON sticking abnormality”, the microcomputer 40 turns on the fuel cut request flag as fail-safe processing for the ON sticking abnormality.
When an on-fixation abnormality occurs in the cylinder deactivation mechanism 31, if combustion occurs by injecting fuel into the cylinders 5-1 to 5-3, the cylinders 5-1 to 5-3 Since it becomes combustion, it causes damage to the engine 3. Therefore, the microcomputer 40 turns on the fuel cut request flag when the determination result is “ON-fixed abnormality” and when it is determined that an ON-fixed abnormality has occurred in the cylinder deactivation mechanism 31. Thus, the fuel cut is performed on the cylinders 5-1 to 5-3.

  However, since the fuel cut request flag is turned off at least from the timing tb until the predetermined time T5 elapses, there is a possibility that fuel is injected into the cylinders 5-1 to 5-3 and combustion occurs. is there. For this reason, this fail-safe process alone is not sufficient in terms of preventing damage to the engine 3.

  In FIG. 8, time T6 is a period in which the fuel injected just before the fuel cut request flag is turned on by fail-safe processing explodes in the cylinders 5-1 to 5-3, and time T7 is This is a time obtained by adding the time T6 and the predetermined time T5. During the time T7, combustion may occur in the sealed cylinders 5-1 to 5-3. Particularly, when the engine 3 rotates at high speed, the number of injections per unit time increases. It is considered that the damage to the engine 3 increases and increases.

<Provisional first plan to prevent engine damage>
As a first proposal for preventing damage to the engine 3 when an on-fixing abnormality occurs in the cylinder deactivation mechanism 31, for example, as shown in FIG. 9, the microcomputer 40 is in the case where the actual cylinder deactivation state is on. For example, there is a plan to turn on the fuel cut request flag. This is because if the fuel cut is performed, combustion in the sealed cylinders 5-1 to 5-3 can be prevented.

  However, simply implementing the first plan makes it difficult to improve the exhaust characteristics immediately after switching the cylinder deactivation mechanism 31 from the second state to the first state when the cylinder deactivation mechanism 31 is normal. become.

  This is because, as shown in FIG. 10, when the cylinder deactivation mechanism 31 is normal, the microcomputer 40 detects that the actual cylinder deactivation state has been turned off from on, and then turns off the fuel cut request flag. It becomes. A delay occurs after the fuel cut request flag is turned off until fuel is actually injected into the cylinders 5-1 to 5-3. For this reason, there is a high possibility that combustion in the cylinders 5-1 to 5-3 after the resumption of operation does not occur normally, leading to deterioration of exhaust characteristics. Specifically, there is a high possibility that fuel injection cannot be performed in the first intake stroke of the cylinders 5-1 to 5-3 that have resumed operation. Therefore, the air sucked into the cylinders 5-1 to 5-3 flows into the exhaust pipe 15 as it is, and the exhaust characteristics are deteriorated. In this case, the exhaust becomes lean.

  In other words, regarding the prevention of deterioration of exhaust characteristics immediately after switching the cylinder deactivation mechanism 31 from the second state to the first state, the cooperative control process of the cylinder deactivation electromagnetic valve 33 and the fuel cut (particularly in FIG. 6). S310 to S390) become meaningless.

<Provisional second plan to prevent damage to the engine>
As a second proposal for preventing damage to the engine 3 when an on-fixing abnormality occurs in the cylinder deactivation mechanism 31, for example, as shown in FIG. 11, the microcomputer 40 is in a case where the actual cylinder deactivation state is on. Another possible idea is to turn on the ignition cut request flag. This is because even if the ignition cut is performed, combustion in the sealed cylinders 5-1 to 5-3 can be prevented.

  However, just like the first plan, the second plan is simply implemented. When the cylinder deactivation mechanism 31 is normal, the exhaust characteristics immediately after switching the cylinder deactivation mechanism 31 from the second state to the first state are obtained. It becomes difficult to be good.

  This is because, as shown in FIG. 12, when the cylinder deactivation mechanism 31 is normal, the microcomputer 40 turns off the ignition cut request flag after detecting that the actual cylinder deactivation state has been turned off from on. It becomes. A delay occurs after the ignition cut request flag is turned off until the cylinders 5-1 to 5-3 are actually ignited. For this reason, there is a high possibility that combustion in the cylinders 5-1 to 5-3 after the resumption of operation does not occur normally, leading to deterioration of exhaust characteristics. Specifically, there is a high possibility that ignition cannot be performed in the first compression stroke of the cylinders 5-1 to 5-3 that have resumed operation. Therefore, the fuel injected into the cylinders 5-1 to 5-3 flows into the exhaust pipe 15 as it is, and the exhaust characteristics are deteriorated. In this case, exhaust becomes rich.

  Therefore, also in this second plan, the cooperative control of the cylinder deactivation electromagnetic valve 33 and the fuel cut is performed with respect to preventing the deterioration of the exhaust characteristic immediately after the cylinder deactivation mechanism 31 is switched from the second state to the first state. Processing becomes meaningless.

For this reason, in the ECU 39 of the present embodiment, the microcomputer 40 executes the cylinder deactivation control process described below, instead of simply implementing the first and second plans.
<Cylinder deactivation control processing>
The microcomputer 40 executes the cylinder deactivation control process shown in FIG. 13 at regular intervals when the engine 3 is in an operating state, for example.

  As shown in FIG. 13, when the microcomputer 40 starts the cylinder deactivation control process, in S510, as a process for calculating the possibility that the cylinder deactivation mechanism 31 is likely to be turned on (hereinafter referred to as an abnormality possibility). Then, the abnormality possibility calculation process of FIG. 14 is executed.

  As shown in FIG. 14, when starting the abnormality possibility calculation process, the microcomputer 40 determines whether or not the actual cylinder deactivation state is on in S610. If the actual cylinder deactivation state is not on (that is, if it is off), the microcomputer 40 proceeds to S630 as it is. If the actual cylinder deactivation state is on, the microcomputer 40 performs the cylinder deactivation mechanism drive time in S620. Is counted up, and then the process proceeds to S630. The cylinder deactivation mechanism drive time is an accumulated time when the cylinder deactivation mechanism 31 is in the second state, in other words, an accumulated operation time of the cylinder deactivation mechanism 31. The measured value of the cylinder deactivation mechanism drive time is stored as a counter in the nonvolatile memory 44, for example.

  In S630, the microcomputer 40 counts up the measured value of the engine driving time. The engine drive time is the accumulated time when the engine 3 is in the operating state, in short, the accumulated operation time of the engine 3. The measured value of the engine driving time is stored as a counter in the nonvolatile memory 44, for example.

  In the next S640, the microcomputer 40 calculates the possibility of abnormality based on the measured value of the cylinder deactivation mechanism drive time and the time indicating the product life of the cylinder deactivation mechanism 31 (hereinafter referred to as product life time). The abnormality possibility calculated in S640 is referred to as a first abnormality possibility P1.

  More specifically, for example, the ROM 42 stores a first data map indicating the relationship among the cylinder deactivation mechanism drive time, the product life time, and the possibility of abnormality as shown in FIG. Then, the microcomputer 40 calculates, from the first data map, an abnormality possibility corresponding to the measured value of the cylinder deactivation mechanism drive time as the first abnormality possibility P1.

The first data map is set for the following purpose.
When the cylinder deactivation mechanism drive time is short, it is considered that the engine 3 has just been assembled, and there is a risk of an initial failure of the cylinder deactivation mechanism 31, so there is a high possibility of abnormality. In addition, when the cylinder deactivation mechanism drive time is approaching the product life time, the possibility of abnormality is high. Therefore, the first data map is set so that the value of “cylinder deactivation mechanism driving time ÷ product life time” is calculated to a value that is more likely to be abnormal as the value is closer to 0 or closer to 1. . Note that the maximum value of the possibility of abnormality calculated based on the first data map is 99%, for example.

  In the next S650, the microcomputer 40 calculates the possibility of abnormality based on the measured value of the cylinder deactivation mechanism drive time and the measured value of the engine drive time. The abnormality possibility calculated in S650 is referred to as a second abnormality possibility P2.

  Specifically, for example, the ROM 42 stores a second data map indicating the relationship between the value of “cylinder deactivation mechanism driving time ÷ engine driving time” and the possibility of abnormality, as shown in FIG. . Then, the microcomputer 40 calculates, from the second data map, the possibility of abnormality corresponding to the value “measured value of cylinder deactivation mechanism drive time ÷ measured value of engine drive time” as the second abnormality possibility P2. To do.

The second data map is set for the following purpose.
When the value of “cylinder deactivation mechanism drive time ÷ engine drive time” is small, the ratio of the time during which the cylinder deactivation mechanism 31 is operating with respect to the operation time of the engine 3 is small. Conceivable. Further, when the value of “cylinder deactivation mechanism drive time ÷ engine drive time” is large, it is highly likely that the cylinder deactivation mechanism 31 is being deteriorated, and thus the possibility of abnormality is high. Therefore, the second data map is set so that the value of “cylinder deactivation mechanism driving time ÷ engine driving time” is calculated to a value that is more likely to be abnormal as the value is closer to 0 or closer to 1. . Note that the maximum value of the possibility of abnormality calculated based on the second data map is also 99%, for example.

  In the next S660, the microcomputer 40 compares the first possibility of abnormality P1 calculated in S640 with the second possibility of abnormality P2 calculated in S650, and determines whether or not “P1> P2”. Determine. If the microcomputer 40 determines in S600 that "P1> P2", the first abnormality possibility P1 is set as an abnormality possibility as a final calculation result in S670, and thereafter The abnormality possibility calculation process is terminated. If the microcomputer 40 determines that “P1> P2” is not satisfied in S660, the second abnormality possibility P2 is set as an abnormality possibility as a final calculation result in S680, and then Then, the abnormality possibility calculation process ends.

  That is, the microcomputer 40 determines the larger one of the first abnormality possibility P1 and the second abnormality possibility P2 as a final calculation result by the abnormality possibility calculation process. When the microcomputer 40 ends the abnormality possibility calculation process, the process proceeds to S520 in FIG.

  Returning to FIG. 13, in S520, the microcomputer 40 executes the above-described cooperative control process of FIG. In step S530, the microcomputer 40 determines whether or not the final determination result obtained by the abnormality determination process of FIG. That is, it is determined by the abnormality determination process whether or not it has been determined that an on-fixation abnormality has occurred.

  If the microcomputer 40 determines in S530 that the confirmation determination result is “ON sticking abnormality”, the microcomputer 40 proceeds to S560, turns on the fuel cut request flag, and then ends the cylinder deactivation control process. Note that the processing in the case of determining YES in S530 and proceeding to S560 corresponds to the fail-safe processing described with reference to FIG.

On the other hand, when the microcomputer 40 determines in S530 that the determination result is not “ON-fixed abnormality”, the microcomputer 40 proceeds to S540 and determines whether or not the actual cylinder deactivation state is ON.
If the microcomputer 40 determines in S540 that the actual cylinder deactivation state is ON, the microcomputer 40 proceeds to S550, and the abnormality possibility calculated in the abnormality possibility calculation process (FIG. 14) in S510 is the first predetermined value. It is determined whether or not the value is Pth1 (for example, 80%) or more.

  If the microcomputer 40 determines in S550 that the possibility of abnormality is greater than or equal to the first predetermined value Pth1, the microcomputer 40 proceeds to S560, turns on the fuel cut request flag, and then ends the cylinder deactivation control process. To do.

  If the microcomputer 40 determines in S550 that the possibility of abnormality is not equal to or greater than the first predetermined value Pth1, the microcomputer 40 proceeds to S570, and the abnormality possibility calculated in the abnormality possibility calculation process in S510 (FIG. 14). It is determined whether or not the property is equal to or greater than a second predetermined value P2 (for example, 60%) that is smaller than the first predetermined value P1.

  If the microcomputer 40 determines in S570 that the possibility of abnormality is greater than or equal to the second predetermined value Pth1, the microcomputer 40 proceeds to S580, turns on the ignition cut request flag, and then ends the cylinder deactivation control process. To do.

  If the microcomputer 40 determines in S540 that the actual cylinder deactivation state is not ON, or if it determines in S570 that the possibility of abnormality is not equal to or greater than the second predetermined value Pth1, Proceed to S590. In step S590, the microcomputer 40 turns off the ignition cut request flag, and then ends the cylinder deactivation control process.

  In the cylinder deactivation control process, even if the fuel cut request flag is set OFF in S280 or S390 of the cooperative control process (FIG. 6) executed in S520, if it is set ON in the same S560, Eventually it turns on. The fuel cut request flag determined by referring to S110 of the fuel cut control process (FIG. 3) is a fuel cut request flag that is finally set to ON or OFF by the cylinder deactivation control process. In S560, the ignition cut request flag may be turned on.

<effect>
When the actual cylinder deactivation state is on and the calculated possibility of abnormality is equal to or greater than a predetermined value (Pth1 or Pth2) (S550 or S570: YES), the microcomputer 39 of the ECU 39 determines the fuel cut request flag or ignition cut The request flag is turned on (S560 or S580). Turning on the fuel cut request flag means requesting the fuel cut control process of FIG. 3 to perform fuel cut on the cylinders 5-1 to 5-3. Turning on the ignition cut request flag is a request for performing the ignition cut on the cylinders 5-1 to 5-3 with respect to the ignition cut control process of FIG. If fuel cut or ignition cut is performed on the cylinders 5-1 to 5-3, combustion is prevented from occurring in the cylinders 5-1 to 5-3.

  In the ECU 39, when the calculated possibility of abnormality is equal to or greater than a predetermined value (Pth1 or Pth2), the fuel cut request flag or the ignition cut is performed by the processing of S560 or S580 in FIG. The request flag is turned on. Therefore, fuel cut or ignition cut is performed on the cylinders 5-1 to 5-3. For this reason, when the cylinder deactivation mechanism 31 is turned on and the cylinder deactivation mechanism 31 does not return from the second state to the first state even when the solenoid valve drive signal is turned off, the sealed cylinder The occurrence of combustion inside 5-1 to 5-3 is reliably prevented without delay. Therefore, damage to the engine 3 is reliably prevented.

  Even if the actual cylinder deactivation state is on, if the calculated possibility of abnormality is less than the predetermined value (Pth2) (S570: NO), the processing of S560 and S580 in FIG. 13 is not executed. For this reason, it is possible to avoid the problem caused by the provisional first plan or the second plan described above in which the fuel cut request flag or the ignition cut request flag is turned on when the actual cylinder deactivation state is on. The problem is that when the normal cylinder deactivation mechanism 31 is switched from the second state to the first state, the exhaust characteristic is caused by a delay until fuel cut or ignition cut is not performed on the cylinders 5-1 to 5-3. It is a defect that causes deterioration.

  That is, in the ECU 39, the process of S560 or S580 in FIG. 13 (hereinafter referred to as the combustion is performed, when the actual cylinder deactivation state is on, the fuel cut request flag or the ignition cut request flag is turned on separately from the cooperative control process) Prevention request processing) is performed on the condition that the calculated possibility of abnormality is a predetermined value or more. For this reason, it is possible to avoid the execution of the combustion prevention request process when the normal cylinder deactivation mechanism 31 is in the second state as much as possible. In other words, when the possibility of abnormality is high, the ECU 39 selects the combustion prevention request process that prioritizes protection of the engine 3 over the deterioration of the exhaust characteristic, and when the possibility of abnormality is low, the ECU 39 reduces the deterioration of the exhaust characteristic. Priority is given to preventable cooperative control processing. Therefore, it is possible to achieve both prevention of damage to the engine 3 and prevention of deterioration of exhaust characteristics.

  Further, in the abnormality possibility calculation process, the microcomputer 40 of the ECU 39 calculates the possibility of abnormality based on the cylinder deactivation mechanism drive time (corresponding to the accumulated operation time) that is the accumulated time when the cylinder deactivation mechanism 31 is in the second state. To do. For this reason, the certainty of the calculated possibility of abnormality can be increased. Furthermore, since the microcomputer 40 of the ECU 39 calculates the possibility of abnormality based on the cylinder deactivation mechanism driving time and the product life time, the certainty of the calculated possibility of abnormality can be further increased.

  Further, in the abnormality possibility calculation process, the microcomputer 40 of the ECU 39 is based on the ratio between the cylinder deactivation mechanism drive time and the engine drive time (corresponding to the cumulative operation time) that is the accumulated time when the engine 3 is in the operating state. Calculate the probability of abnormality. For this reason, the certainty of the calculated possibility of abnormality can be increased.

  Further, in the abnormality possibility calculation process, the microcomputer 40 of the ECU 39 determines the first abnormality possibility P1 calculated based on the cylinder deactivation mechanism drive time and the product life time, the cylinder deactivation mechanism drive time, and the engine drive time. The larger one of the second abnormality possibilities P2 calculated based on the result is determined as a calculation result. Therefore, the certainty of the calculated possibility of abnormality can be further increased.

  As a modification of the abnormality possibility calculation process of FIG. 14, for example, the first abnormality possibility P1 may be used as it is without calculating the second abnormality possibility P2. On the contrary, the second abnormality possibility P2 may be used as it is as the calculation result without calculating the first abnormality possibility P1.

  Further, in S560 in the cylinder deactivation control process of FIG. 13, the microcomputer 40 of the ECU 39 turns on the fuel cut request flag to turn off the fuel cut as a process for preventing combustion in the cylinders 5-1 to 5-3. To be implemented. For this reason, combustion in the sealed cylinders 5-1 to 5-3 can be reliably prevented.

  Further, in S580 in the cylinder deactivation control process of FIG. 13, the microcomputer 40 of the ECU 39 turns on the ignition cut request flag to turn off the ignition cut as a process for preventing combustion in the cylinders 5-1 to 5-3. To be implemented. For this reason, combustion in the sealed cylinders 5-1 to 5-3 can be reliably prevented.

  Further, the microcomputer 40 of the ECU 39 turns on the fuel cut request flag if the calculated possibility of abnormality is not less than the first predetermined value Pth1 when the actual cylinder deactivation state is on (S560 in FIG. 13). If the possibility of abnormality is less than the first predetermined value Pth1 and greater than or equal to the second predetermined value Pth2, the ignition cut request flag is turned on (S580 in FIG. 13).

The reason why the fuel cut and the ignition cut are properly used according to the degree of possibility of abnormality calculated in this way is as follows.
Although the ignition cut cannot prevent useless fuel injection into the cylinders 5-1 to 5-3 unlike the fuel cut when an on-fixation abnormality occurs in the cylinder deactivation mechanism 31, it is compared with the fuel cut. Then, the final timing of implementation and release will be later. This is because the ignition timing is later than the fuel injection timing. For this reason, the ignition cut is more likely to be released immediately when the cylinder deactivation mechanism 31 is normal and switched from the second state to the first state as compared with the fuel cut, leading to deterioration of exhaust characteristics. There is an advantage that it is difficult. On the other hand, the fuel cut is wasteful not only in the combustion in the cylinders 5-1 to 5-3 but also in the cylinders 5-1 to 5-3 when the cylinder deactivation mechanism 31 is actually turned on. There is an advantage that fuel can be prevented from being injected.

  Therefore, in the present embodiment, when the calculated abnormality possibility is very high as the combustion prevention process that is required to be executed when the actual cylinder deactivation state is on, the fuel cut is selected and the calculated abnormality possibility is calculated. If it is slightly high, the ignition cut is selected. By doing in this way, the advantage of fuel cut and the advantage of ignition cut can be utilized to the maximum extent.

  As a modification of the cylinder deactivation control process in FIG. 13, for example, S570 and S580 may be deleted, and the process may be terminated when NO is determined in S550. Regardless of whether or not it is deformed in this way, in S560, as described above, both the fuel cut request flag and the ignition cut request flag may be turned on. By performing both the fuel cut and the ignition cut, it is possible to reliably realize combustion prevention in the sealed cylinders 5-1 to 5-3.

As mentioned above, although embodiment of this invention was described, this invention can take a various form, without being limited to the said embodiment. The above numerical values are examples and other values may be used.
For example, the first predetermined value Pth1 and the second predetermined value Pth2 used for the determination in S550 and S570 of FIG. 13 may be configured to change according to the engine speed. Specifically, the predetermined values Pth1 and Pth2 are preferably set to smaller values as the engine speed is higher (larger). When the engine 3 is rotating at a high speed and the cylinder deactivation mechanism 31 has an on-fixation abnormality, if the combustion is generated in the cylinders 5-1 to 5-3, it is considered that the damage to the engine 3 increases. For this reason, from the viewpoint that the protection of the engine 3 should be prioritized, the predetermined values Pth1 and Pth2 are reduced to facilitate the above-described combustion prevention request processing (S560 or S580 in FIG. 13).

  In addition, the functions of one component in the above embodiment may be distributed as a plurality of components, or the functions of a plurality of components may be integrated into one component. Further, at least a part of the configuration of the above embodiment may be replaced with a known configuration having the same function. Moreover, you may abbreviate | omit a part of structure of the said embodiment. In addition, all the aspects included in the technical idea specified by the wording described in the claims are embodiments of the present invention. In addition to the above-described ECU 39, the present invention is realized in various forms such as a system including the ECU 39 as a constituent element, a program for causing a computer to function as the ECU 39, a medium storing the program, and a control method for an internal combustion engine. You can also

  DESCRIPTION OF SYMBOLS 3 ... Engine, 5-1 to 5-6 ... Cylinder, 5-1 to 5-3 ... Deactivation object cylinder, 25 ... Intake valve, 26 ... Exhaust valve, 31 ... Cylinder deactivation mechanism, 39 ... ECU, microcomputer 40

Claims (9)

A first state in which all of the plurality of cylinders (5-1 to 5-6) are operated, and an intake valve (25) and an exhaust valve of a deactivation target cylinder (5-1 to 5-3) that are part of the cylinder In-cylinder injection internal combustion engine (3) provided with a cylinder deactivation mechanism (31) that switches to a second state in which (26) is fixed in a closed state and deactivates the cylinder to be deactivated in accordance with a given switching instruction. In the internal combustion engine control device (39) for controlling
When a fuel cut is requested for the cylinder to be deactivated, a fuel cut is performed for the cylinder to be deactivated, and when it is requested to release the fuel cut, a fuel cut means (S110 to S110) that stops the fuel cut. S130),
When the cylinder deactivation mechanism is instructed to switch to the second state and the cylinder deactivation mechanism is set to the second state, the switching control for requesting the fuel cut means to perform the fuel cut. Means (S200 to S390),
Said switching control means for switching the cylinder halting mechanism to said first state from said second state, outputs a switching instruction to the first state to the cylinder deactivation mechanism, said cylinder by said switching instruction The fuel cut means is requested to release the fuel cut before the timing at which the pause mechanism is expected to switch from the second state to the first state (S310 to S390).
Further, the internal combustion engine control device includes:
Possibility calculation means (S610 to S680) for calculating the possibility of occurrence of an abnormality in which the cylinder deactivation mechanism remains in the second state;
Prevents combustion from occurring in the cylinder to be deactivated when the cylinder deactivation mechanism is in the second state and the possibility calculated by the possibility calculation means is equal to or greater than a predetermined value. Combustion prevention requesting means (S540 to S580) for requesting execution of the combustion prevention process to the combustion prevention means (S110 to S130, S150 to S170) for performing the combustion prevention process for
An internal combustion engine control device comprising: The internal combustion engine control apparatus according to claim 1,
The possibility calculation means includes:
Calculating the possibility based on a cumulative operation time which is a cumulative time when the cylinder deactivation mechanism is in the second state (S640, S650);
An internal combustion engine control device. The internal combustion engine control apparatus according to claim 2,
The possibility calculation means includes:
Calculating the possibility based on the cumulative operation time and the time indicating the product life of the cylinder deactivation mechanism (S640);
An internal combustion engine control device. The internal combustion engine control apparatus according to claim 2,
The possibility calculation means includes:
Calculating the possibility based on the cumulative operating time and the cumulative operating time which is the cumulative time when the internal combustion engine is in an operating state (S650);
An internal combustion engine control device. The internal combustion engine control apparatus according to any one of claims 2 to 4,
The possibility calculation means includes:
First means (S640) for calculating the possibility based on the cumulative operation time and a time indicating a product life of the cylinder deactivation mechanism;
Second means (S650) for calculating the possibility based on the cumulative operating time and the cumulative operating time which is the cumulative time when the internal combustion engine is in an operating state;
A third means (S660) for determining a larger one of the possibility calculated by the first means and the possibility calculated by the second means as the possibility calculated by the possibility calculating means (S660). To S680),
An internal combustion engine control device. The internal combustion engine control apparatus according to any one of claims 1 to 5,
The combustion prevention process is a fuel cut for the cylinder to be stopped.
The combustion preventing means is the fuel cut means (S110 to S130);
An internal combustion engine control device. The internal combustion engine control apparatus according to any one of claims 1 to 5,
The combustion prevention process is an ignition cut for the cylinder to be stopped.
The combustion preventing means is an ignition cut means (S150 to S170) for performing an ignition cut for the cylinder to be deactivated when an ignition cut for the cylinder to be deactivated is requested;
An internal combustion engine control device. The internal combustion engine control apparatus according to claim 7,
The combustion prevention process is a fuel cut and an ignition cut for the cylinder to be stopped.
The combustion preventing means is the fuel cut means (S110 to S130) and the ignition cut means (S150 to S170);
An internal combustion engine control device. The internal combustion engine control device according to claim 8 ,
The combustion prevention request means includes
If the cylinder deactivation mechanism is in the second state and the possibility is greater than or equal to a first predetermined value, the fuel cut means is requested to perform the fuel cut (S560). ,
The cylinder deactivation mechanism is in the second state, the possibility is less than the first predetermined value, and the possibility is greater than or equal to a second predetermined value that is smaller than the first predetermined value. If so, requesting the ignition cut means to perform the ignition cut (S580),
An internal combustion engine control device.

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