JP2009191703A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine capable of restraining the deterioration in a combustion state in an operation cylinder, by controlling an opening-closing characteristic of an engine valve in a characteristic suitable for combustion in the operation cylinder, even when performing any of whole cylinder operation and cylinder resting operation. <P>SOLUTION: When performing the whole cylinder operation, an ignition timing advance quantity being an operation command value of a variable valve train 13 is calculated so as to become a value suitable for the whole cylinder operation. Thus, the variable valve train 13 is operated based on its ignition timing advance quantity, and the valve timing of an intake valve 9 can be set in an optimal state for the combustion in the operation cylinder in the whole cylinder operation. When performing the cylinder resting operation, the ignition timing advance quantity is calculated so as to become a value suitable for the cylinder resting operation. Thus, the variable valve train 13 is operated based on its ignition timing advance quantity, and the valve timing of the intake valve 9 can be set in an optimal state for the combustion in the operation cylinder in the cylinder resting operation. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  An internal combustion engine mounted on a vehicle such as an automobile is provided with a variable valve mechanism for continuously changing the opening / closing characteristics of an engine valve such as an intake valve or an exhaust valve for the purpose of improving exhaust emission or improving output. Has been put to practical use. Then, in the internal combustion engine provided with the variable valve mechanism, the operation command value of the variable valve mechanism is calculated based on the engine operating state, and the variable valve mechanism is operated based on the operation command value. The opening / closing characteristics are characteristics suitable for the combustion of fuel during engine operation at that time.

  Further, in an internal combustion engine mounted on a vehicle, as cylinder deactivation control, a cylinder that normally performs all cylinder operation to operate all cylinders and stops operation of some cylinders in a predetermined engine operation region One that performs a pause operation is known.

  As such cylinder deactivation control, for example, in Patent Document 1, all cylinder operation is performed during engine high load operation, and cylinder deactivation operation is performed during engine low load operation. This is because, in an internal combustion engine, when an engine high load operation is performed, that is, when an operation in which the amount of air (air mixture) sucked per cycle is increased with respect to the operating cylinder is performed, This is to improve the fuel consumption of the internal combustion engine in consideration of the fuel consumption characteristics of the internal combustion engine.

In the cylinder deactivation control, the cylinder deactivation is performed at the time of engine low-load operation where the fuel efficiency of the internal combustion engine is not good, that is, in a situation where the amount of air (air mixture) taken into the operating cylinder per cycle may decrease. When the operation of some cylinders is stopped by the operation, the amount of air (air mixture) sucked per cycle with respect to the remaining operating cylinders is increased. As a result, the amount of intake air per cycle (the amount of air-fuel mixture) in the operating cylinder during the cylinder deactivation operation is the amount of intake air per cycle in the operating cylinder when the engine becomes a high-load operation in all cylinder operation. The value is close to (amount of air-fuel mixture), and the fuel efficiency of the internal combustion engine during engine low load operation can be improved.
JP-A-5-163971 (paragraphs [0035] and [0036], FIG. 3)

  By the way, when the cylinder deactivation control is executed in the internal combustion engine provided with the variable valve mechanism, the operation command value of the variable valve mechanism is not taken into consideration in switching between the cylinder deactivation operation and the all cylinder operation by the control. If the variable valve mechanism is operated based on the operation command value to control the opening / closing characteristics of the engine valve, the combustion state may deteriorate.

  That is, when the cylinder deactivation operation is performed through the cylinder deactivation control during the engine low load operation, the intake air amount (amount of the air-fuel mixture) per cycle for the operating cylinder becomes the engine high load operation in the all cylinder operation. It becomes a value close to the intake air amount (amount of air-fuel mixture) per cycle in the operating cylinder at that time. Under such circumstances, when the operation command value of the variable valve mechanism is calculated based on the engine operation state on the assumption that all cylinder operation is performed at a low engine load, based on the operation command value. When the variable valve mechanism is operated to control the opening / closing characteristics of the engine valve, the combustion state deteriorates.

  This is an optimum characteristic when the intake air amount per cycle for the operating cylinder is small (low load) with respect to the opening / closing characteristics of the engine valve controlled as described above. This is because when the amount of intake air per cycle for the cylinder is large, the characteristic becomes closer to a lower load than the optimum characteristic. Thus, when the opening / closing characteristics of the engine valve become characteristics closer to the lower load than the optimum characteristics, it is inevitable that the combustion state is deteriorated by that amount.

  The present invention has been made in view of such a situation, and the purpose thereof is to determine whether the engine valve is opened and closed in the operating cylinder regardless of whether all-cylinder operation or cylinder deactivation operation is performed. It is an object of the present invention to provide a control device for an internal combustion engine that can be controlled to have characteristics suitable for the above-described operation and suppress the deterioration of the combustion state in the operating cylinder.

In the following, means for achieving the above object and its effects are described.
In order to achieve the above object, according to the first aspect of the present invention, the opening and closing characteristics of the engine valve in each cylinder are continuously variable by the operation of the variable valve mechanism, and some cylinders are selected according to the engine operating state. This is applied to an internal combustion engine in which a cylinder deactivation operation is performed to stop the operation of the engine, and by operating the variable valve mechanism based on an operation command value calculated based on the engine operation state, the opening / closing characteristics of the engine valve are In the control device for an internal combustion engine that controls the characteristics suitable for operation, when the cylinder deactivation operation is not performed, the operation command value is calculated to be a value corresponding to all cylinder operation in which all cylinders are operated, Calculation means is provided for calculating the operation command value to be a value corresponding to the cylinder deactivation operation when the cylinder deactivation operation is being performed.

  According to the above configuration, when the cylinder deactivation operation is not performed, the operation command value of the variable valve mechanism can be calculated to be a value suitable for all cylinder operation. By operating the variable valve mechanism, the opening / closing characteristics of the engine valve can be made optimal for combustion in the operating cylinders in all cylinder operation. Further, since the operation command value of the variable valve mechanism can be calculated to be a value suitable for the cylinder deactivation operation when the cylinder deactivation operation is being performed, the variable valve mechanism is determined based on the operation command value. By operating the engine valve, it is possible to make the opening / closing characteristic of the engine valve optimal for combustion in the operating cylinder in the cylinder deactivation operation. Therefore, regardless of whether all-cylinder operation or cylinder deactivation operation is performed, the opening / closing characteristics of the engine valve are controlled to be optimal characteristics for combustion in the operating cylinder, and the combustion state in the operating cylinder is deteriorated. Can be suppressed.

  According to a second aspect of the present invention, in the first aspect of the invention, the cylinder deactivation operation is executed when the internal combustion engine is running at a low rotation and a low load, and the calculating means is configured to execute the cylinder deactivation operation. The operation command value is calculated so as to be a value closer to a higher load than the operation command value at the time of execution of all cylinder operation under the same engine operation state.

  When the cylinder deactivation operation is executed at the time of low load and low rotation of the internal combustion engine, the intake air amount (amount of mixture) per cycle in the operating cylinder during the cylinder deactivation operation is the engine high load operation in all cylinder operations. It becomes a value close to the intake air amount (amount of air-fuel mixture) per cycle in the operating cylinder at that time. According to the above configuration, the operation command value of the variable valve mechanism during the cylinder deactivation operation is higher than the operation command value at the time of execution of all cylinder operation under the same engine operation state as that time. Therefore, the opening / closing characteristics of the engine valve when the variable valve mechanism is operated based on the operation command value are characteristics suitable for combustion in the operating cylinder in the cylinder deactivation operation. Therefore, deterioration of the combustion state in the operating cylinder can be avoided.

  According to a third aspect of the present invention, in the second aspect of the present invention, the variable valve mechanism can change a valve timing of the intake valve by changing a relative rotational phase of the intake camshaft with respect to a crankshaft in the internal combustion engine. The calculation means compares the operation command value at the time of executing the cylinder deactivation operation with the operation command value at the time of execution of all the cylinders under the same engine operation state. The value is calculated so as to be a value on the valve timing advance side which is a value closer to the load.

  During engine high-load operation with full cylinder operation, the effect of improving intake charging efficiency by early opening of the intake valve is increased, and as a result, combustion in the internal combustion engine is stably performed. Is preferably close to the advance angle. According to the above configuration, the intake air amount (amount of air-fuel mixture) per cycle in the operating cylinder due to the cylinder deactivation operation during the engine low load operation is 1 in the operating cylinder when the engine high load operation is achieved in all cylinder operation. When the intake air amount per cycle (amount of air-fuel mixture) is close to the value, the calculated operation command value is compared with the value at the valve timing advance side compared to the value at the time of all cylinder operation in the same engine operation state. Is done. Therefore, the valve timing of the engine valve when the variable valve mechanism is operated based on the operation command value is suitable for combustion in the operating cylinder in the cylinder deactivation operation, in other words, all cylinder operation in the same engine operation state. Compared to the time, the timing becomes more advanced, and the deterioration of the combustion state in the operating cylinder is avoided.

  According to a fourth aspect of the present invention, the variable valve mechanism makes the maximum lift amount and operating angle of an intake valve in an internal combustion engine variable, and the calculation means is an operation command for executing the cylinder deactivation operation. The value is compared with the operation command value at the time of execution of all cylinder operation under the same engine operation state, so that the maximum lift amount and the operating angle increase side values that are closer to the higher load are obtained. To be calculated.

  At the time of engine high load operation in all cylinder operation, the maximum lift amount and the operating angle of the intake valve are made closer to increasing from the viewpoint of effectively improving the intake charge efficiency of the internal combustion engine and stabilizing the combustion in the internal combustion engine. It is preferable. According to the above configuration, the intake air amount (amount of air-fuel mixture) per cycle in the operating cylinder due to the cylinder deactivation operation during the engine low load operation is 1 in the operating cylinder when the engine high load operation is achieved in all cylinder operation. When the intake air amount per cycle (amount of air-fuel mixture) becomes close to the value, the calculated operation command value is larger than the value when operating all cylinders in the same engine operating state, and the maximum lift amount and operating angle increase side The value of Therefore, the maximum lift amount and operating angle of the engine valve when the variable valve mechanism is operated based on the operation command value are values suitable for combustion in the operating cylinder in the cylinder deactivation operation, in other words, in the same engine operating state. Compared with the operation of all cylinders, the value is increased, and the deterioration of the combustion state in the operating cylinder is avoided.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the internal combustion engine operates in all cylinders in which all cylinders are operated in accordance with an engine operating state and in operation of some cylinders. Cylinder deactivation control is performed to switch between cylinder deactivation operation and non-execution of the cylinder deactivation control. When the cylinder deactivation control is not performed, all cylinder operation is performed. The engine is executed at low engine speed and low load, and the calculating means calculates an operation command value at the time of execution of the cylinder deactivation operation with reference to a first map based on an engine operation state, and The operation command value at the time of executing the operation is calculated with reference to the second map based on the engine operating state.

  According to the above configuration, as the map for calculating the operation command value of the variable valve mechanism, the first map and the second map are selected depending on whether the cylinder deactivation operation or all-cylinder operation is being performed. Is selected and used. Since the operation command value calculated using each of the first map and the second map can be set so as to differ depending on whether the cylinder deactivation operation or all-cylinder operation is performed, the maps are as described above. Thus, the operation command value can be accurately switched between the one corresponding to the cylinder deactivation operation and the one corresponding to the all cylinder operation.

Hereinafter, an embodiment in which the present invention is applied to an in-line multi-cylinder engine for an automobile will be described with reference to FIGS.
In the engine 1 shown in FIG. 1, the opening degree of the throttle valve 29 provided in the intake passage 3 is adjusted based on the depression amount of the accelerator pedal 17 (accelerator depression amount) and the like, and corresponds to the opening degree of the valve 29. A quantity of air is sucked into the combustion chamber 2 of each cylinder via the intake passage 3. An amount of fuel corresponding to the amount of intake air of the engine 1 is injected and supplied to the intake passage 3 of the engine 1 from the fuel injection valve 4. As a result, an air-fuel mixture consisting of air and fuel is formed in the combustion chamber 2 of each cylinder in the engine 1. When the air-fuel mixture is ignited by the spark plug 5, the air-fuel mixture burns and the piston 6 Reciprocates, and the crankshaft 7 that is the output shaft of the engine 1 rotates. Then, the air-fuel mixture after combustion is sent out from each combustion chamber 2 to the exhaust passage 8 as exhaust gas.

  In each cylinder of the engine 1, the combustion chamber 2 and the intake passage 3 are communicated / blocked by the opening / closing operation of the intake valve 9, and the combustion chamber 2 and the exhaust passage 8 are communicated / opened by the opening / closing operation of the exhaust valve 10. Blocked. The intake valve 9 and the exhaust valve 10 are opened and closed with the rotation of the intake camshaft 11 and the exhaust camshaft 12 to which the rotation of the crankshaft 7 is transmitted. More specifically, a rocker arm 19 having a roller 18 is provided between the intake cam 11a fixed to the intake cam shaft 11 and the intake valve 9, and the rocker arm is based on the pressure of the rotating intake cam 11a against the roller 18. 19 rotates around a contact point with a lash adjuster 20 that supports one end thereof to press the intake valve 9. The intake valve 9 opens and closes based on the pressure of the intake valve 9 by the rocker arm 19. A rocker arm 22 having a roller 21 is provided between the exhaust cam 12a fixed to the exhaust camshaft 12 and the exhaust valve 10, and the rocker arm 22 is based on the pressure of the rotating exhaust cam 12a against the rocker arm 22. Rotates around the contact point with the lash adjuster 23 that supports one end thereof, and presses the exhaust valve 10. The exhaust valve 10 opens and closes based on the pressure of the exhaust valve 10 by the rocker arm 22.

  In the engine 1, in addition to the all-cylinder operation for operating all the cylinders, a cylinder deactivation operation for stopping only some of the cylinders and operating only the remaining cylinders is executed in order to improve fuel efficiency. In such a cylinder deactivation operation, in some cylinders of the engine 1, the fuel injection from the fuel injection valve 4 is stopped and the energization to the spark plug 5 for igniting the air-fuel mixture is stopped, and the intake valve 9 and This is realized by stopping the lift of the exhaust valve 10. The lift stop of the intake valve 9 and the exhaust valve 10 is performed by lift stop mechanisms 24 and 25 provided on the rocker arms 19 and 22.

  The lift stop mechanism 24 is provided on the rocker arm 19 between the intake cam 11a and the intake valve 9 in order to stop the lift (opening / closing) of the intake valve 9 based on the pressure of the intake cam 11a against the rocker arm 19 (roller 18). It has been. The lift stop mechanism 24 can be switched between a state in which the roller 18 can move relative to the rocker arm 19 in the direction of pressing and a state in which the relative movement is prohibited. It is in a prohibited state. In this state, when the roller 18 is pressed by the intake cam 11a, the rocker arm 19 is rotated as described above to open and close the intake valve 9. On the other hand, when the lift of the intake valve 9 is stopped, the lift stop mechanism 24 is switched to a state in which the roller 18 can move relative to the rocker arm 19. In this case, when the roller 18 is pressed by the intake cam 11a, the roller 18 moves relative to the rocker arm 19, so that the rocker arm 19 does not rotate so as to open and close the intake valve 9, but the intake cam 11a. The lift of the intake valve 9 accompanying the rotation of is stopped.

  The lift stop mechanism 25 is provided on the rocker arm 19 between the exhaust cam 12a and the exhaust valve 10 in order to stop the lift (opening / closing) of the exhaust valve 10 based on the pressure of the exhaust cam 12a against the rocker arm 22 (roller 21). It has been. The lift stop mechanism 25 has the same structure as the lift stop mechanism 24 described above, and the state in which the roller 21 can be moved relative to the rocker arm 22 in the pressing direction and the state in which the relative movement is prohibited. In the normal state, the relative movement of the roller 21 with respect to the rocker arm 22 is prohibited. In this state, when the roller 21 is pressed by the exhaust cam 12a, the rocker arm 22 rotates as described above to open and close the intake valve 9. On the other hand, when the lift of the intake valve 9 is stopped, the lift stop mechanism 25 is switched to a state in which the roller 21 can move relative to the rocker arm 22. In this case, when the roller 21 is pressed by the exhaust cam 12a, the roller 21 moves relative to the rocker arm 22, so that the rocker arm 22 does not rotate to open and close the exhaust valve 10, and the exhaust cam 12a. The lift of the exhaust valve 10 accompanying this rotation is stopped.

  The engine 1 is provided with a variable valve mechanism 13 that continuously changes the opening / closing characteristics of the intake valve 9 among the engine valves such as the intake valve 9 and the exhaust valve 10. The variable valve mechanism 13 changes the valve timing of the intake valve 9 by changing the relative rotational phase of the intake camshaft 11 with respect to the crankshaft 7. Through the driving of the variable valve mechanism 13, the valve opening timing and valve closing timing of the valve 9 are both advanced or retarded while the valve opening period (operating angle) of the intake valve 9 is kept constant. This is an optimum state for engine operation (combustion of air-fuel mixture).

Next, the electrical configuration of the control device for the engine 1 in the present embodiment will be described.
This control device is provided with an electronic control device 26 that performs various controls such as operation control of the engine 1. The electronic control unit 26 includes a CPU that executes arithmetic processing related to the various controls, a ROM that stores programs and data necessary for the control, a RAM that temporarily stores arithmetic results of the CPU, and an external device. An input / output port for inputting / outputting signals is provided.

Various sensors shown below are connected to the input port of the electronic control unit 26.
An accelerator position sensor 28 that detects the amount of depression (accelerator depression amount) of the accelerator pedal 17 that is depressed by the driver of the automobile.

A throttle position sensor 30 that detects the opening (throttle opening) of the throttle valve 29 provided in the intake passage 3.
An air flow meter 32 for detecting the amount of air taken into the combustion chamber 2 through the intake passage 3;

A crank position sensor 34 that outputs a signal corresponding to the rotation of the crankshaft 7 and is used for calculation of the engine rotation speed or the like.
A water temperature sensor 35 that detects the cooling water temperature of the engine 1.

  The output port of the electronic control unit 26 is connected to the fuel injection valve 4, the spark plug 5, the variable valve mechanism 13, the lift stop mechanisms 24 and 25, the drive circuit for the throttle valve 29, and the like.

  The electronic control unit 26 then grasps the engine operating state such as the accelerator depression amount, the throttle opening, the intake air amount, the engine rotation speed, and the engine load based on the detection signals input from the various sensors. The engine speed is obtained based on a detection signal from the crank position sensor 34. Further, the engine load is calculated from the intake air amount of the engine 1 and the engine rotation speed obtained based on detection signals from the accelerator position sensor 28, the throttle position sensor 30, the air flow meter 32, and the like. The electronic control unit 26 outputs a command signal to various drive circuits connected to the output port according to the engine operating state described above. Thus, various controls such as fuel injection control of the fuel injection valve 4, ignition timing control of the spark plug 5, control of the valve timing of the intake valve 9, drive control of the lift stop mechanisms 24 and 25, and opening control of the throttle valve 29 are performed. This is implemented through the electronic control unit 26.

Next, cylinder deactivation control for switching between all-cylinder operation and cylinder deactivation operation of the engine 1 according to the engine operation state will be described in detail.
The cylinder deactivation operation in the cylinder deactivation control is realized by stopping the operation of some cylinders of the engine 1. In some cylinders that are stopped in this way (hereinafter referred to as idle cylinders), the fuel injection by the fuel injection valve 4 and the ignition stop by the spark plug 5 are stopped, and the intake valve 9 by the lift stop mechanisms 24 and 25 is stopped. And the lift stop of the exhaust valve 10 is performed. As for the idle cylinder, the same cylinder may be always used when the cylinder idle operation is executed, or a different cylinder may be used every time the cylinder idle operation is executed. When the same cylinder is always used as the idle cylinder when performing the cylinder idle operation, the lift stop mechanisms 24 and 25 are omitted in the cylinders other than the idle cylinder, and the rollers 18 and 21 are provided directly on the rocker arms 19 and 22. It is preferable for suppressing an increase in the number of parts.

  In the cylinder deactivation control, the switching between the all cylinder operation and the cylinder deactivation operation is performed with reference to the map shown in FIG. This map defines a cylinder deactivation region AP that is an engine operation region in which the cylinder deactivation operation in the cylinder deactivation control is performed based on the engine rotation speed and the engine load, and is an area other than the cylinder deactivation region AP. This defines an all-cylinder region AA that is an engine operation region in which cylinder operation is performed. The cylinder deactivation region AP is set to a low rotation / low load region, and the all cylinder region AA is set to a higher rotation / high load region than the cylinder deactivation region AP. When the engine rotation speed and the engine load are within the cylinder deactivation region AP, the cylinder deactivation operation is performed, and when the engine rotation speed and the engine load are within the all cylinder region AA, the all cylinder operation is performed.

  As described above, in the cylinder deactivation control, the cylinder deactivation operation is performed when the engine 1 is in the low rotation and low load operation, and the all cylinder operation is performed in other cases. This is because when the engine 1 is operated with a high engine load, that is, when the engine 1 is operated with a large amount of air (air mixture) sucked per cycle with respect to the operating cylinder, This is because the fuel efficiency tends to be good, and the fuel efficiency of the engine 1 is improved in consideration of the fuel efficiency characteristics of the engine 1.

  In the cylinder deactivation control, the cylinder deactivation is performed during engine low-load operation where the fuel consumption of the engine 1 is not good, that is, when there is a possibility that the amount of air (air mixture) sucked into the operating cylinder per cycle will decrease. When the operation of some cylinders is stopped by the operation, the amount of air (air mixture) sucked per cycle with respect to the remaining operating cylinders is increased. As a result, the amount of intake air per cycle (the amount of air-fuel mixture) in the operating cylinder during the cylinder deactivation operation is the amount of intake air per cycle in the operating cylinder when the engine becomes a high-load operation in all cylinder operation. It becomes a value close to (amount of air-fuel mixture), and the fuel efficiency of the engine 1 during low load operation can be improved.

  Incidentally, in order to improve the fuel consumption of the engine 1, it is preferable to expand as much as possible the engine operating range in which the cylinder deactivation operation is performed in the cylinder deactivation control. However, if the engine operation region in which the cylinder deactivation operation is performed is excessively expanded, the combustion may be deteriorated in the operating cylinder in the cylinder deactivation operation depending on the engine operation state. For example, when the engine operating range in which the cylinder deactivation operation is performed is excessively expanded to the high load side, the engine operation state is in the high load side operation region in the engine operation region in which the cylinder deactivation operation is performed. Then, the combustion in the operating cylinder during the cylinder deactivation operation is deteriorated. The deterioration of the combustion in the operating cylinder occurs because the amount of air to be inhaled per cycle for the operating cylinder by the execution of the cylinder deactivation operation under the above-described condition exceeds the actually inhalable amount. This is presumably because it affects the combustion of the air-fuel mixture. Therefore, in the cylinder deactivation control, the cylinder deactivation region AP is determined in consideration of the above situation, and the cylinder deactivation operation is performed only in the region AP, and in the all cylinder region AA other than the region, all cylinder operation is performed. Like to do.

  FIG. 3 is a flowchart showing a cylinder deactivation control routine for executing the cylinder deactivation control described above. This cylinder deactivation control routine is periodically executed through the electronic control unit 26, for example, with a time interruption every predetermined time.

  In this routine, first, as a process for determining whether or not the temperature of the engine 1 is a value at which the cylinder deactivation control can be performed, a predetermined value A where the cooling water temperature of the engine 1 is the execution water temperature of the cylinder deactivation control. It is determined whether or not it is higher (S101). It should be noted that when the engine 1 is in a low temperature where it is difficult to maintain a good combustion state due to a decrease in the volatility of the fuel or the like, there is a problem that the execution of the cylinder deactivation operation in the cylinder deactivation control deteriorates the combustion state in the operating cylinder. There is a risk of occurrence. Regarding the predetermined value A, a value determined in advance through experiments or the like is used as a value that does not cause the above-described problem when the cylinder deactivation operation is performed.

  If the determination in step S101 is negative, cylinder deactivation control is stopped (S105), and all cylinder operation is performed. If the determination in step S101 is affirmative, cylinder deactivation control is executed using the map shown in FIG. 2 (S102 to S104 in FIG. 3). More specifically, with reference to the map, it is determined whether or not the engine operation state such as the engine rotation speed and the engine load is in an operation region (cylinder deactivation region AP) where the cylinder deactivation operation is performed in the cylinder deactivation control. (S102). If the engine operation state is in the cylinder deactivation region AP, the cylinder deactivation operation is executed (S103), and if the engine operation state is not in the cylinder deactivation region AP but in the all cylinder region AA, all cylinder operation is performed (S104). .

Next, the valve timing control of the intake valve 9 in the engine 1 will be described in detail.
With respect to the valve timing control, an advance amount that is an operation command value of the variable valve mechanism 13 is calculated based on an engine operating state such as an engine speed and an engine load, and the mechanism 13 is operated based on the advance amount. This is realized by changing the relative rotation phase of the intake camshaft 11 with respect to the crankshaft 7. When the relative rotation phase of the intake camshaft 11 with respect to the crankshaft 7 is changed, as shown in FIG. 4, the valve opening timing and closing of the valve 9 are maintained while maintaining the valve opening period (operating angle) of the intake valve 9 constant. Both valve timings are advanced or retarded. When the valve timing control is performed as described above, the valve timing of the intake valve 9 is made appropriate for the engine operation (combustion state) at that time. The valve timing of the intake valve 9 controlled in this way is the most retarded state when the advance amount is “0”, and is advanced as the advance amount is increased.

  By the way, in the valve timing control of the intake valve 9, if the advance amount (operation command value) is calculated without taking into account the switching between the cylinder deactivation operation by the cylinder deactivation control and the all cylinder operation, the calculation is performed. When the variable valve mechanism 13 is operated based on the amount of advance, and the valve timing of the intake valve 9 is controlled, the combustion state may deteriorate.

  That is, when the cylinder deactivation operation is performed through the cylinder deactivation control during the engine low load operation, the intake air amount (amount of the air-fuel mixture) per cycle for the operating cylinder becomes the engine high load operation in the all cylinder operation. It becomes a value close to the intake air amount (amount of air-fuel mixture) per cycle in the operating cylinder at that time. Under such circumstances, assuming that the cylinder deactivation control is not performed and all cylinder operation is being performed, if the advance amount is calculated based on the engine operating state, the advance amount may be determined based on the advance amount. When the variable valve mechanism 13 is operated and the valve timing of the intake valve 9 is controlled, the combustion state is deteriorated.

  This is a state where the valve timing of the intake valve 9 controlled as described above is optimum when the amount of intake air per cycle for the operating cylinder is small (low load). This is because when the amount of intake air per cycle for the operating cylinder is large, the load becomes closer to a lower load than the optimum valve timing. Thus, if the valve timing of the intake valve 9 becomes closer to a lower load than the optimum timing (a state closer to the retarded angle), it is inevitable that the combustion state is deteriorated by that amount.

  FIG. 5 is a flowchart showing a variable valve mechanism operation control routine for controlling the operation of the variable valve mechanism 13 so as to suppress the valve timing of the intake valve 9 without causing the above-described problems. The variable valve mechanism operation control routine is periodically executed through the electronic control unit 26, for example, with a time interruption every predetermined time.

In this routine, processing for switching the variable valve mechanism 13 between the operation-permitted state and the operation-prohibited state is executed according to the engine operating state (in this example, the coolant temperature).
Specifically, it is determined whether or not the coolant temperature of the engine 1 is higher than a predetermined value B (S201). If a negative determination is made here, the temperature of the engine 1 is low and the fuel volatility is decreased. In relation to this, since it becomes difficult to maintain a good combustion state by the valve timing control, the variable valve mechanism 13 is disabled (S207). In such an operation prohibition state of the variable valve mechanism 13, the variable valve mechanism 13 is controlled so that the valve timing of the intake valve 9 is fixed to a predetermined state, for example, the most retarded state. As for the predetermined value B, the operation-permitted water temperature of the variable valve mechanism 13 is a value corresponding to the temperature of the engine 1 (cooling water temperature) at which a good combustion state can be maintained by the valve timing control. A value determined in advance by experiment or the like is used. The predetermined value B in this embodiment is a value smaller than the predetermined value A that is an execution water temperature of cylinder deactivation control.

  If it is determined in step S201 that the coolant temperature of the engine 1 is higher than the predetermined value B, the variable valve mechanism 13 is allowed to operate and the valve timing control is executed (S202 to S206). .

  Specifically, when the cooling water temperature of the engine 1 is higher than a predetermined value A that is the execution water temperature of the cylinder deactivation control (S202: YES), and the cylinder deactivation operation under the control is being performed (S203: YES). In step S204, the advance amount which is the operation command value of the variable valve mechanism 13 is calculated based on the engine speed and the engine load with reference to the first map shown in FIG. This first map is for calculating the advance amount corresponding to the cylinder deactivation operation, and the advance angle capable of setting the valve timing of the intake valve 9 to the optimum timing corresponding to the cylinder deactivation operation. It is set in advance by experiments or the like so that the amount can be obtained. On the other hand, when the coolant temperature of the engine 1 is equal to or lower than the predetermined value A and all cylinders are operated (S202: NO), or when all cylinders are operated under cylinder deactivation control (S203: NO) ) Is calculated based on the engine rotational speed and the engine load with reference to the second map shown in FIG. 7 (S205). This second map is for calculating the advance amount corresponding to the all-cylinder operation, and the advance angle capable of setting the valve timing of the intake valve 9 to the optimum timing corresponding to the all-cylinder operation. It is set in advance by experiments or the like so that the amount can be obtained. Thereafter, by operating the variable valve mechanism 13 based on the calculated advance angle (S206), the valve timing of the intake valve 9 is controlled to a state corresponding to the advance angle.

  When the cylinder deactivation operation is not performed and the all cylinder operation is performed, the advance amount is calculated to be a value suitable for the all cylinder operation. Therefore, the variable valve mechanism 13 is based on the advance amount. It is possible to set the valve timing of the intake valve 9 to an optimum state for combustion in the operating cylinder in all cylinder operation. Further, when the cylinder deactivation operation is being performed, the advance amount is calculated so as to be a value suitable for the cylinder deactivation operation, so that the variable valve mechanism 13 is operated based on the advance amount and the intake valve 9 is operated. It is possible to make the valve timing optimal for combustion in the operating cylinder in the cylinder deactivation operation. Therefore, regardless of whether all-cylinder operation or cylinder deactivation operation is performed, the valve timing of the intake valve 9 is controlled to an optimum state for combustion in the operating cylinder, and the combustion state in the operating cylinder is deteriorated. It becomes possible to suppress the occurrence.

Here, the first map and the second map will be described in detail with reference to FIGS.
As can be seen from FIG. 7, in all-cylinder operation, the combustion state of the engine 1 becomes better as the engine load increases, in other words, as the intake air amount (mixture amount) per cycle in the operating cylinder increases. The advance amount is increased to maintain. As a result, the valve timing of the intake valve 9 becomes more advanced as the advance amount increases. In this way, the valve timing of the intake valve 9 is advanced because the higher the load of the engine 1 and the larger the intake air amount (mixture amount) per cycle in the operating cylinder, the more the valve timing of the intake valve 9 increases. This is because the effect of improving the intake charging efficiency due to the early opening of the valve at the advance angle is increased, whereby the combustion in the engine 1 can be performed stably.

  Further, as can be seen from FIG. 6, in the cylinder deactivation operation, the advance amount is calculated only when the engine 1 is under low rotation and low load. This is because the cylinder deactivation operation is performed only when the rotation is low and the load is low. In the cylinder deactivation operation, as the engine load increases, in other words, as the intake air amount (amount of air-fuel mixture) per cycle in the operating cylinder increases, the advance amount increases so as to maintain the combustion state of the engine 1 in the region. Increased. As a result, the valve timing of the intake valve 9 becomes more advanced as the advance amount increases. However, the advance amount calculated during the cylinder deactivation operation is a value closer to a higher load than the advance amount when all cylinder operation is performed under the same engine operation state (FIG. 7). It is a certain value on the increase side, in other words, a value on the side that further advances the valve timing of the intake valve 9.

  In the cylinder deactivation operation, the intake air amount per cycle (amount of air-fuel mixture) in the operating cylinder is the same as the intake air amount per cycle in the operating cylinder (the mixture air Value). In such cylinder deactivation operation, the variable valve mechanism 13 is operated based on the advance amount calculated as described above, and the valve timing of the intake valve 9 is controlled. The timing is optimal for the combustion of the cylinder, that is, the timing is on the more advanced side than when all cylinders are operating in the same engine operating state. Therefore, the valve timing of the intake valve 9 in the active cylinder in the cylinder deactivation operation is controlled to the same timing as in the all cylinder operation, so that the state is closer to the lower load than the optimum timing (timing on the retard side). It is avoided that the combustion state deteriorates in the operating cylinder.

According to the embodiment described in detail above, the following effects can be obtained.
(1) When all-cylinder operation is being performed, the advance amount, which is the operation command value of the variable valve mechanism 13, is calculated to be a value suitable for all-cylinder operation. It is possible to operate the variable valve mechanism 13 so that the valve timing of the intake valve 9 is optimal for combustion in the operating cylinder in all cylinder operation. Further, when the cylinder deactivation operation is being performed, the advance amount is calculated so as to be a value suitable for the cylinder deactivation operation, so that the variable valve mechanism 13 is operated based on the advance amount and the intake valve 9 is operated. It is possible to make the valve timing optimal for combustion in the operating cylinder in the cylinder deactivation operation. Therefore, regardless of whether all-cylinder operation or cylinder deactivation operation is performed, the valve timing of the intake valve 9 is controlled to an optimum state for combustion in the operating cylinder, and the combustion state in the operating cylinder is deteriorated. It becomes possible to suppress the occurrence.

  (2) In the all-cylinder operation, the effect of improving the intake charging efficiency due to the early opening of the intake valve 9 becomes greater as the engine 1 is operated at a higher load, and thereby the combustion in the engine 1 can be stably performed. Since it is possible, the advance amount which is the operation command value of the variable valve mechanism 13 is increased, and the valve timing of the intake valve 9 is set to the advance side. On the other hand, in the cylinder deactivation operation, the advance amount that is the operation command value of the variable valve mechanism 13 is more than the advance amount when the all cylinder operation is performed under the same engine operation state. It is a value on the increasing side that is a value close to a high load, in other words, a value that further advances the valve timing of the intake valve 9. In this cylinder deactivation operation, the amount of intake air per cycle (amount of air-fuel mixture) in the operating cylinder is the amount of intake air per cycle (air-fuel mixture) in the operating cylinder when the engine becomes a high load operation in all cylinder operations. Value). Therefore, in the cylinder deactivation operation, the variable valve mechanism 13 is operated based on the advance amount calculated as described above, and the valve timing of the intake valve 9 is controlled, so that the valve timing is the operating cylinder in the cylinder deactivation operation. The timing is optimal for combustion in the engine, that is, the timing is on the more advanced side than when all cylinders are operating in the same engine operating state. As a result, the valve timing of the intake valve 9 in the operating cylinder in the cylinder deactivation operation is controlled to the same timing as in the operation of all cylinders, thereby becoming a state closer to the lower load than the optimum timing (timing on the retard side), It is avoided that the combustion state deteriorates in the operating cylinder.

  (3) As a map for calculating the advance amount, which is the operation command value of the variable valve mechanism 13, the first map (FIG. 6) is selected depending on whether the cylinder deactivation operation or all-cylinder operation is being performed. ) And the second map (FIG. 7) are selected and used. Since the first map and the second map are set so that the advance amount calculated using each of them differs depending on whether the cylinder is deactivated or all the cylinders are operated, the maps are described above. By selecting and using in this manner, the advance amount can be accurately switched between the one corresponding to the cylinder deactivation operation and the one corresponding to the all cylinder operation.

In addition, the said embodiment can also be changed as follows, for example.
In the cylinder deactivation operation, the lift (opening / closing) of the engine valves such as the intake valve 9 and the exhaust valve 10 is stopped by the lift stop mechanisms 24 and 25 in the cylinders whose operation is stopped. There is no need. That is, the lift stop mechanisms 24 and 25 may be omitted in the cylinders whose operation is suspended, and the lift of the engine valve may not be stopped. Even in this case, the intake air amount (amount of air-fuel mixture) per cycle in the operating cylinder during the cylinder deactivation operation is equal to the intake air amount per cycle in the active cylinders during all cylinder operation in the same engine operation state. More compared. This is because when the engine output decreases as the cylinder deactivation operation is performed, the driver increases the amount of accelerator depression in order to compensate for the decrease, and accordingly, the throttle valve 29 is opened and the air passing through the intake passage 3 is increased. This is because the amount increases. That is, as the amount of air passing through the intake passage 3 increases in this way, the amount of intake air (amount of air-fuel mixture) per cycle in the operating cylinder during the cylinder deactivation operation also increases.

  -Formulas for calculating the advance amount corresponding to all cylinder operation and formulas for calculating the advance amount corresponding to cylinder deactivation operation are prepared, and the calculation formula for calculating the advance amount As an alternative, one of the above two calculation formulas may be selected and used depending on whether the cylinder is deactivated or all cylinders are operated.

  The present invention may be applied to an engine provided with a variable valve mechanism that varies the maximum lift amount and the operating angle in synchronization with each other as shown in FIG. In this case, the target operating angle is calculated as a drive command value for the variable valve mechanism based on the engine operating state such as the engine rotation speed and the engine load, and the variable valve mechanism is operated based on the target operating angle, whereby the intake valve 9 The maximum lift amount and the operating angle of the engine are set to values suitable for the combustion of the air-fuel mixture in the engine operation at that time.

  In such all-cylinder operation of the engine, the maximum lift amount and the operating angle of the intake valve 9 are improved from the viewpoint of effectively improving the intake charge efficiency of the engine and stabilizing the combustion in the engine as the engine is operated at a high load. Is preferably set to an increasing value. On the other hand, in the cylinder deactivation operation performed at the time of engine low load operation, the intake air amount (the amount of air-fuel mixture) per cycle in the operating cylinder is one cycle in the operating cylinder when the engine becomes high load operation in all cylinder operation. The value is close to the amount of intake air per unit (the amount of air-fuel mixture). For this reason, it is preferable that the maximum lift amount and the operating angle of the intake valve 9 be larger than those during all cylinder operation in the same engine operation state during the cylinder deactivation operation.

  In consideration of the above, the target operating angle during the cylinder deactivation operation is calculated with reference to the first map shown in FIG. 9 based on the engine rotation speed and the engine load, and the engine rotation speed during all cylinder operation and Based on the engine load, it is calculated with reference to the second map shown in FIG. As can be seen from these figures, the target operating angle during the cylinder deactivation operation (solid line in FIG. 9 and the two-dot chain line in FIG. 10) is compared with the target operating angle during all cylinder operation (solid line in FIG. 10). It is a value on the increase side that is a value closer to a higher load, in other words, a value on the side that further increases the maximum lift amount and operating angle of the intake valve 9.

  Therefore, the maximum lift amount and the operating angle of the intake valve 9 when the variable valve mechanism is operated based on the target operating angle during the cylinder deactivation operation are values suitable for combustion in the operating cylinder in the cylinder deactivation operation, in other words, the same. This is a value on the increase side as compared with the case of all cylinder operation in the engine operation state. As a result, the maximum lift amount and the operating angle of the intake valve 9 in the active cylinder in the cylinder deactivation operation are controlled to the same values as in the all cylinder operation, thereby reducing the value closer to the lower load than the appropriate value (the value on the decrease side). Therefore, it is avoided that the combustion state deteriorates in the operating cylinder. The calculation of the target operating angle corresponding to the cylinder deactivation operation can be performed using a calculation formula corresponding to the operation instead of using the first map. Also, the calculation of the target operating angle corresponding to the all-cylinder operation can be performed using a calculation formula corresponding to the same operation instead of using the second map.

  -Open / close characteristics such as valve timing, maximum lift, and operating angle of the intake valve 9 during cylinder deactivation are closer to higher loads compared to the open / close characteristics during all cylinder operation under the same engine operating condition. The present invention may be applied to an engine that can be operated as a characteristic of the above.

  The number of deactivated cylinders (the number of operating cylinders) during the cylinder deactivation operation may not be fixed, but may be variable according to the engine operation state or the like. For example, the number of deactivated cylinders may be increased as the engine 1 has a lower rotation and load, in other words, the number of operating cylinders may be decreased. In this case, the operation command value corresponding to the number of operating cylinders such as calculating the operation command value of the variable valve mechanism in the cylinder deactivation operation to be closer to a higher load as the number of operating cylinders in the cylinder deactivation operation increases. Is preferably calculated.

  The present invention may be applied to an engine having a variable valve mechanism that makes the opening / closing characteristics of the exhaust valve 10, for example, the valve timing of the valve 10 variable.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows the whole engine with which the control apparatus of this embodiment is applied. A map defining all cylinder regions and cylinder deactivation regions in cylinder deactivation control. The flowchart which shows the execution procedure of cylinder deactivation control. The timing chart which shows the change of the opening / closing characteristic of an intake valve by operation | movement of a variable valve mechanism. The flowchart which shows the control procedure of operation | movement of a variable valve mechanism. A first map used for calculating an advance amount in all cylinder operation. The 2nd map used for calculation of the amount of advance in cylinder deactivation operation. The timing chart which shows the change of the opening / closing characteristic of an intake valve by operation | movement of a variable valve mechanism. The 1st map used for calculation of the target operating angle in all cylinder operation. The 2nd map used for calculation of the target operating angle in cylinder deactivation operation.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Combustion chamber, 3 ... Intake passage, 4 ... Fuel injection valve, 5 ... Spark plug, 6 ... Piston, 7 ... Crankshaft, 8 ... Exhaust passage, 9 ... Intake valve, 10 ... Exhaust valve, 11 ... intake camshaft, 11a ... intake cam, 12 ... exhaust camshaft, 12a ... exhaust cam, 13 ... variable valve mechanism, 17 ... accelerator pedal, 18 ... roller, 19 ... rocker arm, 20 ... lash adjuster, 21 ... roller, DESCRIPTION OF SYMBOLS 22 ... Rocker arm, 23 ... Rush adjuster, 24, 25 ... Lift stop mechanism, 26 ... Electronic control unit (calculation means), 28 ... Accelerator position sensor, 29 ... Throttle valve, 30 ... Throttle position sensor, 32 ... Air flow meter, 34 ... Crank position sensor, 35 ... Water temperature sensor.

Claims (5)

An internal combustion engine in which the opening / closing characteristics of the engine valve in each cylinder are continuously variable by the operation of the variable valve mechanism, and the cylinder deactivation operation is performed to stop the operation of some cylinders according to the engine operating state. In the control device for an internal combustion engine, which is applied and operates the variable valve mechanism based on an operation command value calculated based on an engine operating state, thereby controlling the opening / closing characteristics of the engine valve to characteristics suitable for engine operation,
When the cylinder deactivation operation is not executed, the operation command value is calculated to be a value corresponding to the all cylinder operation for operating all cylinders, and when the cylinder deactivation operation is being performed, the operation command value is the same. A control device for an internal combustion engine, comprising: calculation means for calculating a value corresponding to cylinder deactivation operation. The cylinder deactivation operation is executed at the time of low rotation and low load of the internal combustion engine,
The calculation means compares the operation command value at the time of execution of the cylinder deactivation operation with an operation command value at the time of execution of all cylinder operation under the same engine operation state, The control device for an internal combustion engine according to claim 1, wherein the control device is calculated as follows. The variable valve mechanism is configured to change the valve timing of the intake valve by changing the relative rotational phase of the intake camshaft with respect to the crankshaft in the internal combustion engine.
The calculation means compares the operation command value at the time of execution of the cylinder deactivation operation with an operation command value at the time of execution of all cylinder operation under the same engine operation state, and is a value closer to a higher load. The control device for an internal combustion engine according to claim 2, wherein the control is calculated so as to be a value on a certain valve timing advance side. The variable valve mechanism is a variable of a maximum lift amount and an operating angle of an intake valve in an internal combustion engine,
The calculation means compares the operation command value at the time of execution of the cylinder deactivation operation with an operation command value at the time of execution of all cylinder operation under the same engine operation state, and is a value closer to a higher load. The control device for an internal combustion engine according to claim 2, wherein the control device calculates the maximum lift amount and the operating angle increase side. The internal combustion engine performs cylinder deactivation control for switching between all cylinder operation for activating all cylinders and cylinder deactivation operation for suspending operation of some cylinders according to the engine operation state. All-cylinder operation,
The cylinder deactivation operation is performed at the time of low rotation and low load of the internal combustion engine during execution of the cylinder deactivation control,
The calculation means calculates an operation command value at the time of executing the cylinder deactivation operation with reference to a first map based on the engine operation state, and calculates an operation command value at the time of execution of the all cylinder operation based on the engine operation state. The control device for an internal combustion engine according to any one of claims 1 to 4, which is calculated with reference to a second map.

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