JP2010084706A - Control system for variable cylinder internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control system for a variable cylinder internal combustion engine wherein technology for satisfactory operation is developed in either case: where in a cylinder-reduced operation, at least either one of the intake and exhaust valves of a resting cylinder is suspended in a closed-valve state; and where in a cylinder-reduced operation, the intake and exhaust valves of the resting cylinder are operated. <P>SOLUTION: By the control system, operations of the internal combustion engine 1 can be switched between the whole cylinder operation and a cylinder-reduced operation. The control system includes an EGR system 30, an intake valve-timing variable-mechanism 9, and an exhaust valve-timing variable-mechanism 10; the following relation is established: a desired fresh-air amount in the whole cylinder operation>a target fresh-air amount in the valve-operation cylinder-reduced operation>a target fresh-air amount in the valve-stopped cylinder-reduced operation; and the fresh-air amount is made different from each other between the valve-stopped cylinder-reduced operation and the valve-operated cylinder-reduced operation. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for a variable cylinder internal combustion engine.

It is known to switch the operation of an internal combustion engine between an all-cylinder operation in which all cylinders are operated and a reduced-cylinder operation in which some cylinders are operated and the remaining cylinders are deactivated. And the technique of making EGR gas amount supplied to an internal combustion engine different by all-cylinder driving | operation and reduction-cylinder driving | operation using an EGR apparatus is disclosed (for example, refer patent document 1).
JP 2004-27971 A Japanese Patent Laid-Open No. 5-321706 JP-A-8-74610

  By the way, during the reduced-cylinder operation, there are a case where the intake valve and exhaust valve of the deactivated cylinder are stopped in a closed state and a case where the intake valve and exhaust valve of the deactivated cylinder are operated.

  When stopping the intake valve and exhaust valve of the deactivated cylinder in the closed state during the reduced-cylinder operation, if the intake air amount (fresh air amount) is large, the intake air (fresh air) that should be originally supplied to the deactivated cylinder Is also supplied to the working cylinder. For this reason, the amount of fresh air supplied to the operating cylinder increases, and the EGR rate indicating the ratio of the amount of EGR gas in the total amount of intake air (total amount of intake air) that combines the amount of fresh air and the amount of EGR gas decreases. NOx discharged from the internal combustion engine increases, and exhaust emission deteriorates.

  On the other hand, when operating the intake valve and the exhaust valve of the idle cylinder during the reduced cylinder operation, fresh air is taken into the idle cylinder and the fresh air is discharged as it is to become exhaust. The amount of exhaust increases compared to when the intake valve and the exhaust valve are stopped in the closed state. For this reason, the supercharging pressure by the action | operation of a turbocharger becomes high. Therefore, the total intake amount to be supplied to the internal combustion engine increases. Here, when operating the intake valve and exhaust valve of the idle cylinder during the reduced cylinder operation, the same fresh air amount as when stopping the intake valve and exhaust valve of the idle cylinder during the reduced cylinder operation is supplied. If only this is done, a large amount of EGR gas is supplied to the internal combustion engine in order to obtain an increased total intake air amount to be supplied to the internal combustion engine due to insufficient fresh air amount. As a result, the amount of EGR gas supplied to the internal combustion engine may increase excessively, leading to misfire.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a control device for a variable cylinder internal combustion engine in which at least one of an intake valve and an exhaust valve of a deactivated cylinder is closed during a reduced cylinder operation. An object of the present invention is to provide a technique for operating an internal combustion engine satisfactorily regardless of whether it is stopped or when the intake valve and exhaust valve of a deactivated cylinder are operated during reduced-cylinder operation.

In the present invention, the following configuration is adopted. That is, the present invention
A control device for a variable cylinder internal combustion engine capable of switching the operation of the internal combustion engine between full cylinder operation and reduced cylinder operation,
An EGR device that takes in a part of exhaust gas from the exhaust passage of the internal combustion engine as EGR gas and recirculates the EGR gas to the intake passage of the internal combustion engine;
A variable valve mechanism capable of changing an opening / closing characteristic of at least one of an intake valve and an exhaust valve in each cylinder of the internal combustion engine;
When at least one of the intake and exhaust valves of the idle cylinder is stopped in the closed state via the variable valve mechanism during the reduced cylinder operation, and the intake and exhaust valves of the idle cylinder are operated during the reduced cylinder operation. The intake air amount control means for making the intake air amount different depending on the case,
A control apparatus for a variable cylinder internal combustion engine.

  In the present invention, at least one of the intake valve and the exhaust valve of the idle cylinder is stopped in a closed state via the variable valve mechanism during the reduced cylinder operation, and the intake valve and the exhaust valve of the idle cylinder are reduced during the cylinder reduction operation. The amount of intake air is different depending on when the is operated.

  According to the present invention, when at least one of the intake valve and the exhaust valve of the idle cylinder is stopped in the closed state via the variable valve mechanism during the reduced cylinder operation, the intake air amount can be reduced. For this reason, the intake air that should originally be supplied to the idle cylinder is not supplied to the operating cylinder. As a result, the EGR rate indicating the ratio of the EGR gas amount in the total intake air amount including the intake air amount and the EGR gas amount is suppressed from decreasing, and NOx discharged from the internal combustion engine is suppressed from increasing. The exhaust emission can be prevented from deteriorating.

  On the other hand, when the intake and exhaust valves of the idle cylinder are operated during the reduced cylinder operation, intake air is taken into the idle cylinder and the intake air is discharged as it is to become exhaust. As compared with the case where at least one of the intake valve and the exhaust valve is stopped in a closed state via the variable valve mechanism, the exhaust amount increases. For this reason, the supercharging pressure by the action | operation of a turbocharger becomes high. Therefore, the total intake air amount that is the sum of the intake air amount and the EGR gas amount to be supplied to the internal combustion engine increases. Here, according to the present invention, when the intake valve and the exhaust valve of the idle cylinder are operated during the reduced cylinder operation, at least one of the intake valve and the exhaust valve of the idle cylinder is provided with the variable valve mechanism during the reduced cylinder operation. The amount of intake air can be increased as compared with the case where the valve is stopped in the closed state. Therefore, since a large amount of intake air is supplied to the internal combustion engine, a large amount of EGR gas supplied to the internal combustion engine is suppressed in order to obtain an increased total intake air amount to be supplied to the internal combustion engine. Thereby, it can suppress that the amount of EGR gas supplied to an internal combustion engine increases excessively, and it leads to misfire.

  Accordingly, when at least one of the intake valve and the exhaust valve of the deactivated cylinder is stopped in the closed state during the reduced-cylinder operation, it is possible to suppress deterioration of the exhaust emission. Further, when the intake valve and the exhaust valve of the idle cylinder are operated during the reduced-cylinder operation, it is possible to suppress the amount of EGR gas supplied to the internal combustion engine from excessively increasing and causing misfire. Thus, in either case, the internal combustion engine can be operated satisfactorily.

  The intake air amount control means reduces the intake air amount when the intake valve and exhaust valve of the deactivated cylinder are operated during the reduced cylinder operation, than the intake air amount during the all cylinder operation, and during the reduced cylinder operation. It is preferable to increase the intake air amount when at least one of the intake valve and the exhaust valve of the deactivated cylinder is stopped in the closed state via the variable valve mechanism.

  According to the present invention, when at least one of the intake valve and the exhaust valve of the idle cylinder is stopped in a closed state via the variable valve mechanism during the reduced cylinder operation, the intake air amount is minimized and the optimum It can be an amount. Further, when the intake valve and exhaust valve of the idle cylinder are operated during the reduced cylinder operation, at least one of the intake valve and the exhaust valve of the idle cylinder is closed via the variable valve mechanism during the reduced cylinder operation. The amount of intake air can be increased to an optimum amount as compared with the case where the operation is stopped.

The intake air amount control means determines the intake air amount when all cylinders are operated when at least one of the intake valve and the exhaust valve of the idle cylinder is stopped in the closed state via the variable valve mechanism during the reduced cylinder operation. The amount of intake air at that time may be divided by the total number of cylinders and multiplied by the number of operating cylinders.

  According to the present invention, the intake air amount when the at least one of the intake valve and the exhaust valve of the idle cylinder is stopped in the closed state via the variable valve mechanism during the reduced-cylinder operation can be set to an optimal amount. it can.

  The intake air amount control means allows the intake air amount when the intake valve and exhaust valve of the deactivated cylinder are operated during the reduced cylinder operation, and allows at least one of the intake valve and exhaust valve of the deactivated cylinder during the reduced cylinder operation. When the intake air amount is stopped in the closed state via the variable valve mechanism, at least one of the intake valve and the exhaust valve of the idle cylinder is stopped in the closed state via the variable valve mechanism during the cylinder reduction operation. It is good to divide by the supercharging pressure in the case where the engine is in operation and multiply the supercharging pressure in the case where the intake valve and exhaust valve of the idle cylinder are operated during the reduced cylinder operation.

  According to the present invention, the intake air amount when the intake valve and the exhaust valve of the idle cylinder are operated during the reduced cylinder operation can be set to an optimal amount.

  According to the present invention, in the control apparatus for a variable cylinder internal combustion engine, when at least one of the intake valve and the exhaust valve of the deactivated cylinder is stopped in the closed state during the reduced cylinder operation, and the intake valve of the deactivated cylinder during the reduced cylinder operation The internal combustion engine can be operated satisfactorily regardless of whether the exhaust valve is operated.

  Specific examples of the present invention will be described below.

<Example 1>
FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which the control device for a variable cylinder internal combustion engine according to the present embodiment is applied and its intake system and exhaust system. An internal combustion engine 1 shown in FIG. 1 is a water-cooled four-stroke cycle diesel engine having four cylinders 2. The internal combustion engine 1 is mounted on a vehicle. The cylinder head 3 of the internal combustion engine 1 is provided with an intake port 5 and an exhaust port 6 that communicate with the combustion chamber 4 in the cylinder 2. The cylinder head 3 is provided with an intake valve 7 for opening and closing the intake port 5 and an exhaust valve 8 for opening and closing the exhaust port 6.

  The intake valve 7 is provided with a variable valve mechanism that changes the opening / closing characteristics of the intake valve 7. As this variable valve mechanism, an intake valve valve timing variable mechanism 9 for changing an opening / closing timing (valve timing) which is an opening / closing characteristic of the intake valve 7 is provided. The intake valve valve timing variable mechanism 9 is a mechanism for continuously changing the opening / closing timing of the intake valve 7.

  The exhaust valve 8 is provided with a variable valve mechanism that changes the opening / closing characteristics of the exhaust valve 8. As this variable valve mechanism, there is provided an exhaust valve valve timing variable mechanism 10 for changing an opening / closing timing (valve timing) which is an opening / closing characteristic of the exhaust valve 8. The variable exhaust valve valve timing mechanism 10 is a mechanism for continuously changing the opening / closing timing of the exhaust valve 8.

  The cylinder head 3 is provided with a fuel injection valve 11 that injects fuel into the cylinder 2 of the internal combustion engine 1.

  An intake passage 12 that communicates with the intake port 5 and an exhaust passage 13 that communicates with the exhaust port 6 are connected to the cylinder head 3.

In the middle of the intake passage 12 connected to the internal combustion engine 1, a compressor 14a of a turbocharger 14 that operates using exhaust energy as a drive source is disposed.

  An air flow meter 15 that detects the amount of intake air (fresh air amount) that is taken in from the outside and supplied to the internal combustion engine 1 is disposed in the intake passage 12 upstream of the compressor 14a. An intercooler 16 that performs heat exchange between the intake air and the outside air is disposed in the intake passage 12 downstream of the compressor 14a. A throttle valve 17 that adjusts the amount of fresh air supplied to the internal combustion engine 1 is disposed in the intake passage 12 downstream of the intercooler 16. The throttle valve 17 is opened and closed by an electric actuator. These intake passages 12 and devices arranged in the intake passages 12 constitute an intake system for taking intake air into the internal combustion engine 1.

  On the other hand, a turbine 14 b of a turbocharger 14 is arranged in the middle of the exhaust passage 13 connected to the internal combustion engine 1. The turbine 14b is driven by exhaust gas flowing through the exhaust passage 13, and the compressor 14a rotates with the driven turbine 14b to supercharge intake air (fresh air) flowing through the intake passage 12.

  An exhaust purification device 18 is disposed in the exhaust passage 13 downstream of the turbine 14b. The exhaust purification device 18 is configured to include an oxidation catalyst and a diesel particulate filter (hereinafter simply referred to as a filter) disposed at a subsequent stage of the oxidation catalyst. The filter carries a NOx storage reduction catalyst (hereinafter simply referred to as NOx catalyst). The filter has a characteristic of collecting particulate matter (Particulate Matter: hereinafter referred to as PM) such as soot (SOOT) and SOF in the exhaust gas flowing through the exhaust passage 13. The NOx catalyst has a characteristic of storing NOx and SOx in the exhaust gas flowing through the exhaust passage 13 when the exhaust air-fuel ratio is lean. The exhaust passage 13 and the devices arranged in the exhaust passage 13 constitute an exhaust system for exhausting exhaust gas from the internal combustion engine 1.

  The internal combustion engine 1 is provided with an EGR device (Exhaust Gas Recirculation System) 30 that recirculates (recirculates) part of the exhaust gas flowing through the exhaust passage 13 to the intake passage 12. In this embodiment, the exhaust gas recirculated by the EGR device 30 is referred to as EGR gas.

  The EGR device 30 includes an EGR passage 31 through which EGR gas flows, and an EGR valve 32 that adjusts the flow rate of the EGR gas through the EGR passage 31.

  The EGR passage 31 connects the exhaust passage 13 upstream of the turbine 14 b and the intake passage 12 downstream of the throttle valve 17. Through this EGR passage 31, exhaust gas is sent to the internal combustion engine 1 as EGR gas at a high pressure.

  The EGR valve 32 adjusts the amount of EGR gas flowing through the EGR passage 31 by adjusting the passage sectional area of the EGR passage 31. The EGR valve 32 is opened and closed by an electric actuator.

  The internal combustion engine 1 configured as described above is provided with an ECU 19 that is an electronic control unit for controlling the internal combustion engine 1. The ECU 19 is a device that controls the operating state of the internal combustion engine 1 in accordance with the operating conditions of the internal combustion engine 1 and the request of the driver.

  Various sensors such as an air flow meter 15, a crank position sensor 20, and an accelerator position sensor 21 are connected to the ECU 19 through electrical wiring, and output signals from these various sensors are input to the ECU 19.

On the other hand, the ECU 19 is connected to the intake valve valve timing variable mechanism 9, the exhaust valve valve timing variable mechanism 10, the fuel injection valve 11, and the electric actuators of the throttle valve 17 and the EGR valve 32 through electric wiring. The ECU 19 controls these devices.

  The ECU 19 receives the output signals from the crank position sensor 20 and the accelerator position sensor 21, etc., determines the operating state of the internal combustion engine 1, and electrically controls the internal combustion engine 1 and the above devices based on the determined engine operating state. .

  By the way, the internal combustion engine 1 according to the present embodiment is configured such that the operation of the internal combustion engine 1 is an all-cylinder operation in which all four cylinders of the internal combustion engine 1 are operated by supplying fuel from the fuel injection valves 11 to operate all the cylinders. For example, for example, two cylinders are operated and two cylinders are deactivated, fuel is supplied from the fuel injection valve 11 to some cylinders, the some cylinders are operated, and the fuel supply to the remaining cylinders is stopped, and the remaining cylinders are stopped. This is a variable-cylinder internal combustion engine that can be switched between a reduced-cylinder operation in which the cylinders are operated while being stopped. The reduced-cylinder operation is performed to improve fuel efficiency when the vehicle speed shifts to a low speed range, or when the vehicle stops and the internal combustion engine 1 shifts to idling operation.

  Here, at the time of reduced cylinder operation, when the intake valve 7 and the exhaust valve 8 of the idle cylinder are stopped in a closed state via the intake valve valve timing variable mechanism 9 and the exhaust valve valve timing variable mechanism 10 (hereinafter, this case) Is referred to as “valve stop reduced cylinder operation”, and when the intake valve 7 and exhaust valve 8 of the idle cylinder are operated in the same manner as in operation (hereinafter, this case is referred to as “valve operated reduced cylinder operation”).

  In the stop cylinder reduction operation, in the idle cylinder, the intake valve 7 and the exhaust valve 8 are stopped in the closed state via the intake valve valve timing variable mechanism 9 and the exhaust valve timing variable mechanism 10, and fresh air is taken into the idle cylinder. To prevent it. Thereby, it is possible to prevent the exhaust from the cold fresh air from being discharged from the idle cylinder, to raise the exhaust temperature, and to warm up the exhaust purification device 18.

  On the other hand, in the valve-operated reduced cylinder operation, the intake valve 7 and the exhaust valve 8 are operated in accordance with each stroke similarly to the operation in the idle cylinder, so that fresh air is taken in the idle cylinder and the fresh air is discharged as it is. It becomes. As a result, the cool fresh air exhaust is discharged from the idle cylinder, and the exhaust temperature is lowered, so that the excessive temperature rise of the exhaust purification device 18 can be avoided. Further, when a high supercharging pressure due to the operation of the turbocharger 14 is required, the exhaust amount is also discharged from the idle cylinder, so that the exhaust amount can be increased and the efficiency of the turbocharger 14 can be increased.

  Thus, the valve stop reduced cylinder operation and the valve operated reduced cylinder operation can be used properly according to the situation.

  Here, at the time of valve stop reduction cylinder operation, if the amount of fresh air is large, fresh air that should originally be supplied to the deactivated cylinder is also supplied to the operating cylinder. For this reason, the amount of fresh air supplied to the operating cylinder increases, and the EGR rate indicating the ratio of the amount of EGR gas in the total amount of intake air (total amount of intake air) that combines the amount of fresh air and the amount of EGR gas decreases. NOx discharged from the internal combustion engine 1 increases, and exhaust emission deteriorates. In addition, since the EGR valve 32 is controlled based on the fresh air amount detected by the air flow meter 15, the amount of fresh air is too large unless the target fresh air amount is the amount excluding the fresh air amount for the idle cylinders. Therefore, the EGR gas does not enter and the correct EGR rate cannot be obtained.

On the other hand, at the time of valve-operated reduced cylinder operation, fresh air is discharged as it is even in the deactivated cylinder and becomes exhaust gas. Therefore, the amount of exhaust becomes larger than that at the time of valve stopped reduced cylinder operation. For this reason, the supercharging pressure by the operation of the turbocharger 14 is increased. Therefore, the total intake amount to be supplied to the internal combustion engine 1 increases. Here, when only the same amount of fresh air as that at the time of valve stop reduction cylinder operation is supplied during the valve operation reduction cylinder operation, the increase in the total intake air amount to be supplied to the internal combustion engine 1 is obtained due to insufficient fresh air amount. Therefore, a large amount of EGR gas is supplied to the internal combustion engine 1. Thereby, the amount of EGR gas supplied to the internal combustion engine 1 may increase excessively, leading to misfire.

  Therefore, in this embodiment, the fresh air amount is made different between the valve stop reduced cylinder operation and the valve operated reduced cylinder operation. That is, different target fresh air amounts are set for the valve stop reduced cylinder operation and the valve operated reduced cylinder operation so that the actual fresh air amount detected by the air flow meter 15 becomes the respective target fresh air amount. The throttle valve 17 and the EGR valve 32 are controlled.

Specifically, the target fresh air volume during valve stop reduced cylinder operation is
Target fresh air volume during valve stop reduced cylinder operation = Target fresh air volume during all cylinder operation x number of operating cylinders / total number of cylinders (Equation 1)
Set to the amount calculated in.

  As a result, the amount of fresh air during valve stop reduced cylinder operation can be made equal to the amount of fresh air during all cylinder operation divided by the number of all cylinders and multiplied by the number of operating cylinders.

Also, the target fresh air volume during valve operation reduced cylinder operation is
Target fresh air volume during valve-operated reduced cylinder operation = Target fresh air quantity during valve-stop reduced cylinder operation x Supercharging pressure during valve-operated reduced cylinder operation / Supercharged pressure during valve-stop reduced cylinder operation (Expression) 2)
Set to the amount calculated in.

  As a result, the amount of fresh air during valve-operated reduced cylinder operation is divided by the boost pressure during valve-operated reduced cylinder operation divided by the boost pressure during valve-operated reduced cylinder operation, It can be the multiplied amount.

  The target fresh air amount at the time of valve stop reduced cylinder operation and the target fresh air amount at the time of valve operation reduced cylinder operation are mapped in advance so that they can be derived from the fuel injection amount and the engine speed by experiments and verification.

Here, the supercharging pressure during valve-operated reduced cylinder operation is higher than that during valve-stop reduced cylinder operation, and the target fresh air amount during valve-operated reduced cylinder operation is higher than the target fresh air amount during all cylinder operation. There are few. Therefore, as shown in FIG. 2B, if the fuel injection amount and the engine speed are the same as shown in FIG.
The relationship of target fresh air amount during all cylinder operation> target fresh air amount during valve operation reduced cylinder operation> target fresh air amount during valve stop reduced cylinder operation is established.

  That is, a relationship is established in which the fresh air amount during the valve-actuated reduced cylinder operation is reduced below the fresh air amount during the all-cylinder operation and is increased more than the fresh air amount during the valve stop reduced cylinder operation.

  According to this embodiment, during the valve stop reduced cylinder operation, the target fresh air amount is smaller than the target fresh air amount during all cylinder operation or valve operated reduced cylinder operation, so the fresh air amount is smaller than in other cases. The smallest optimal amount. For this reason, fresh air that should be supplied to the deactivated cylinder is not taken into the internal combustion engine 1 and is not supplied to the operating cylinder. Thereby, it can suppress that an EGR rate falls, can suppress that NOx discharged | emitted from the internal combustion engine 1 increases, and can suppress that exhaust emission deteriorates. Further, since the EGR valve 32 is controlled based on the fresh air amount detected by the air flow meter 15 and the target fresh air amount is obtained by subtracting the fresh air amount for the deactivated cylinder, the fresh air amount is the optimum amount. The EGR gas is contained in an optimum amount, and a correct EGR rate can be obtained.

On the other hand, at the time of valve-operated reduced cylinder operation, fresh air is taken into the deactivated cylinder, and the new air is discharged as it is to become exhaust gas. For this reason, the supercharging pressure by the action | operation of the turbocharger 14 becomes high. Therefore, the total intake air amount that combines the fresh air amount and the EGR gas amount to be supplied to the internal combustion engine 1 increases. Here, according to this embodiment, during valve operation reduced cylinder operation, the target fresh air amount is greater than during valve stop reduced cylinder operation, and the new air amount is greater than that during valve stop reduced cylinder operation. . Therefore, since a larger amount of fresh air is supplied to the internal combustion engine 1, it is possible to suppress the supply of a large amount of EGR gas to the internal combustion engine 1 in order to obtain an increased total intake air amount to be supplied to the internal combustion engine 1. . Thereby, it can suppress that the amount of EGR gas supplied to the internal combustion engine 1 increases excessively and leads to misfire.

  Therefore, it is possible to suppress the exhaust emission from deteriorating during the valve stop reducing cylinder operation. Further, during valve operation reduced cylinder operation, it is possible to suppress the amount of EGR gas supplied to the internal combustion engine 1 from excessively increasing and causing misfire. Thus, in either case, the internal combustion engine 1 can be operated satisfactorily.

  Next, an all-cylinder operation and reduced-cylinder operation control routine according to this embodiment will be described. FIG. 3 is a flowchart showing an all-cylinder operation and reduced-cylinder operation control routine according to this embodiment. This routine is repeatedly executed by the ECU 19 every predetermined time.

  In step S101, it is determined whether or not the reduced cylinder operation is possible. Specifically, when the operation state of the internal combustion engine 1 is detected from the output values of various sensors and the vehicle speed shifts to a low speed range, or the vehicle stops and the internal combustion engine 1 shifts to idling operation. Judge that reduced-cylinder operation is possible.

  If it is determined in step S101 that the reduced cylinder operation is not possible, the process proceeds to step S102. If it is determined in step S101 that the reduced-cylinder operation is possible, the process proceeds to step S103.

  In step S102, all-cylinder operation for operating all four cylinders is performed. After the processing of this step, this routine is once ended.

  On the other hand, in step S103, it is determined whether or not the valve stop reduced cylinder operation is possible. Specifically, when the exhaust purification device 18 needs to be warmed up, it is determined that the valve stop reduced cylinder operation is possible. Further, when it is necessary to avoid overheating of the exhaust purification device 18 or when a high supercharging pressure is required, it is determined that the valve stop reduced cylinder operation is impossible.

  If it is determined in step S103 that the valve stop reduced cylinder operation is possible, the process proceeds to step S104. If it is determined in step S103 that the valve stop reduced cylinder operation is not possible, the process proceeds to step S106.

  In step S104, the fuel injection valve 11 uses a map as shown in FIG. 2 (a) in which the target fresh air amount at the time of the valve stop reduction cylinder operation calculated by (Equation 1) is created in advance by experiment, verification, or the like. This is derived from the amount of fuel injection and the engine speed detected from the crank position sensor 20.

  In step S105, the predetermined cylinder is deactivated, and in the deactivated cylinder, the intake valve 7 and the exhaust valve 8 are stopped in the closed state via the intake valve valve timing variable mechanism 9 and the exhaust valve valve timing variable mechanism 10, and the valve Implement stop-cylinder operation. At this time, the throttle valve 17 and the EGR valve 32 are controlled such that the actual fresh air amount detected by the air flow meter 15 becomes the target fresh air amount at the time of valve stop reduction cylinder operation derived in step S104. After the processing of this step, this routine is once ended. In addition, ECU19 which performs step S104-105 corresponds to the intake air amount control means of this invention.

On the other hand, in step S106, fuel injection is performed using the map shown in FIG. 2 (a), in which the target fresh air amount during the valve-operated reduced cylinder operation calculated by (Equation 2) is created in advance through experiments, verifications, and the like. Valve 1
1 and the engine speed detected from the crank position sensor 20.

  In step S107, the predetermined cylinder is deactivated, and also in the deactivated cylinder, the intake valve 7 and the exhaust valve 8 are operated in the same manner as during operation, and the valve operation reduced cylinder operation is performed. At this time, the throttle valve 17 and the EGR valve 32 are controlled so that the actual fresh air amount detected by the air flow meter 15 becomes the target fresh air amount at the time of valve stop reducing cylinder operation derived in step S106. After the processing of this step, this routine is once ended. In addition, ECU19 which performs step S106-107 is equivalent to the intake air amount control means of this invention.

  According to this routine described above, the internal combustion engine 1 can be operated satisfactorily in either the valve stop reduction cylinder operation or the valve operation reduction cylinder operation. And according to a situation, all cylinder operation, valve stop reduction cylinder operation, and valve operation reduction cylinder operation can be used properly.

  In the present embodiment, in the valve stop reduced cylinder operation, both the intake valve 7 and the exhaust valve 8 are stopped in the closed state via the intake valve valve timing variable mechanism 9 and the exhaust valve valve timing variable mechanism 10 in the closed cylinder. It was set as the structure made to do. However, the present invention is not limited to this. In the valve stop reduced cylinder operation, it is only necessary to prevent fresh air from being taken into the idle cylinder. For this reason, for example, the configuration may be such that the intake valve 7 is stopped in the closed state via the intake valve valve timing variable mechanism 9, or the exhaust valve 8 is stopped in the closed state via the exhaust valve valve timing mechanism 10. It is possible to have a configuration that only allows

  The control device for a variable cylinder internal combustion engine according to the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the scope of the present invention.

1 is a diagram showing a schematic configuration of an internal combustion engine and an intake system / exhaust system thereof according to Embodiment 1. FIG. (A) is a map for deriving the target fresh air amount according to the first embodiment, and (b) is during all cylinder operation, valve stop reduced cylinder operation, and valve operated reduced cylinder operation according to the first embodiment. The figure which shows the target fresh air amount when a fuel injection amount and an engine speed are the same. 3 is a flowchart showing an all-cylinder operation and reduced-cylinder operation control routine according to the first embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Cylinder 3 Cylinder head 4 Combustion chamber 5 Intake port 6 Exhaust port 7 Intake valve 8 Exhaust valve 9 Intake valve valve timing variable mechanism 10 Exhaust valve valve timing variable mechanism 11 Fuel injection valve 12 Intake passage 13 Exhaust passage 14 Turbocharger 14a Compressor 14b Turbine 15 Air flow meter 17 Throttle valve 18 Exhaust gas purification device 19 ECU
20 Crank position sensor 21 Accelerator position sensor 30 EGR device 31 EGR passage 32 EGR valve

Claims (4)

A control device for a variable cylinder internal combustion engine capable of switching the operation of the internal combustion engine between full cylinder operation and reduced cylinder operation,
An EGR device that takes in a part of exhaust gas from the exhaust passage of the internal combustion engine as EGR gas and recirculates the EGR gas to the intake passage of the internal combustion engine;
A variable valve mechanism capable of changing an opening / closing characteristic of at least one of an intake valve and an exhaust valve in each cylinder of the internal combustion engine;
When at least one of the intake and exhaust valves of the idle cylinder is stopped in the closed state via the variable valve mechanism during the reduced cylinder operation, and the intake and exhaust valves of the idle cylinder are operated during the reduced cylinder operation. The intake air amount control means for making the intake air amount different depending on the case,
A control apparatus for a variable cylinder internal combustion engine, comprising:   The intake air amount control means reduces the intake air amount when the intake valve and exhaust valve of the deactivated cylinder are operated during the reduced cylinder operation, than the intake air amount during the all cylinder operation, and during the reduced cylinder operation. 2. The variable cylinder internal combustion engine according to claim 1, wherein at least one of the intake valve and the exhaust valve of the deactivated cylinder is larger than an intake air amount when the valve is stopped in a closed state via the variable valve mechanism. Engine control device.   The intake air amount control means determines the intake air amount when all cylinders are operated when at least one of the intake valve and the exhaust valve of the idle cylinder is stopped in the closed state via the variable valve mechanism during the reduced cylinder operation. The control apparatus for a variable cylinder internal combustion engine according to claim 2, wherein the intake air amount at that time is divided by the total number of cylinders and multiplied by the number of operating cylinders.   The intake air amount control means allows the intake air amount when the intake valve and exhaust valve of the deactivated cylinder are operated during the reduced cylinder operation, and allows at least one of the intake valve and exhaust valve of the deactivated cylinder during the reduced cylinder operation. When the intake air amount is stopped in the closed state via the variable valve mechanism, at least one of the intake valve and the exhaust valve of the idle cylinder is stopped in the closed state via the variable valve mechanism during the cylinder reduction operation. 4. The amount obtained by dividing by the supercharging pressure when the engine is in operation and multiplying by the supercharging pressure when operating the intake valve and exhaust valve of the idle cylinder during the reduced cylinder operation. Control device for variable cylinder internal combustion engine.

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