JP2006077645A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine which can combine fuel efficiency performance and exhaust cleaning performance more effectively. <P>SOLUTION: An electronic control device performs the operation of an engine while switching between a first operation mode and a second operation mode and maintaining the operation of all the cylinders 1 to 6. The first operation mode makes a rate of sharing of output among cylinders of either of the cylinder groups small as compared to a rate of sharing of output among cylinders of the other cylinder groups. Then the second operation mode equalizes a rate of sharing of output of all the cylinders 1 to 6. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control device for an internal combustion engine having a plurality of cylinder groups connected to different exhaust purification catalysts.

  For example, as can be seen in Patent Document 1, it is well known to perform full cylinder operation in which all cylinders are operated and partial cylinder operation in which some cylinders are deactivated. In such an internal combustion engine, fuel consumption can be improved by performing partial cylinder operation during low load operation and reducing the substantial displacement of the internal combustion engine. In cylinder deactivation, the intake valve is held closed by a variable lift mechanism (variable valve mechanism) that stops the fuel supply and ignition of the target cylinder, or the maximum lift amount of the intake valve is variable, as seen in Patent Document 2. Then, the intake to the target cylinder is stopped.

  By the way, the internal combustion engine of Patent Document 1 is configured as a V-type internal combustion engine in which cylinders are alternately arranged in parallel, and each bank thereof is connected to an individual exhaust pipe provided with an exhaust purification catalyst. Has been. In the partial cylinder operation, only the cylinders in one bank are operated. In this way, when the cylinders that are deactivated during the partial cylinder operation and the cylinders that are continuously operated are connected to the individual exhaust purification catalysts, the partial cylinders are included in the exhaust purification catalyst connected to the deactivated cylinder side. During operation, no exhaust gas passes. Therefore, if the partial cylinder operation is continued for a long time, the temperature of the exhaust purification catalyst connected to the deactivated cylinder side decreases, and when returning to full cylinder operation, the exhaust gas of the internal combustion engine is warmed until the exhaust purification catalyst warms up again. The purification performance will be reduced.

Therefore, in the one described in Patent Document 1, the temperature of the exhaust purification catalyst connected to the idle cylinder side is monitored during partial cylinder operation, and when the temperature drops below a certain value, the partial cylinder operation is stopped and the entire cylinder is stopped. By returning to the cylinder operation, the above-described deterioration of the exhaust purification performance is avoided.
JP 2001-227369 A JP 7-310514 A

  If the partial cylinder operation is stopped in this way, it is certainly possible to prevent the catalyst temperature from being lowered to the inactive region and to avoid the exhaust purification performance from being lowered. However, in this case, the opportunity to perform the partial cylinder operation decreases, and as a result, the effect of improving the fuel efficiency is naturally limited.

  However, if the idle cylinder is set so that a cylinder that continues to operate remains in any exhaust purification catalyst during partial load operation, the above-described reduction in exhaust purification performance due to a decrease in catalyst temperature can be avoided. . However, in such a case, air exhausted from the idle cylinder is sent to any exhaust purification catalyst, and the oxygen concentration of the exhaust gas becomes high, so there is a possibility that exhaust purification cannot be performed sufficiently. Further, there is a possibility that an excessive oxygen supply causes an excessive oxidation / reduction reaction of the exhaust component in the exhaust purification catalyst, resulting in excessive temperature rise of the exhaust purification catalyst.

  The present invention has been made in view of such circumstances, and a problem to be solved is to provide a control device for an internal combustion engine that can more effectively achieve both fuel efficiency and exhaust purification performance. It is in.

In the following, means for achieving the above object and its effects are described.
First, the invention according to claim 1 is a control device for an internal combustion engine having a plurality of cylinder groups each connected to a different exhaust purification catalyst, and maintains the operation of all the cylinders while maintaining the operation of each cylinder group. While switching between the first operation mode in which the output sharing ratio of the cylinder is smaller than the output sharing ratio of each cylinder in the other cylinder group and the second operation mode in which the output sharing ratio of all the cylinders is made equal. The gist is to run the engine.

  According to the above configuration, in the second operation mode, the engine operation is performed in a state where the output sharing ratio (required output of the internal combustion engine, that is, the ratio of the output of each cylinder to the sum of the outputs of all cylinders) is made equal for all the cylinders. Done. That is, all cylinders of the internal combustion engine are operated with equal output.

  On the other hand, in the first operation mode, while the operation of all the cylinders is maintained, the output sharing ratio of each cylinder of the cylinder group connected to the specific exhaust purification catalyst is reduced, and accordingly, the output share of each cylinder of the other cylinder group is reduced. The engine is operated with the output sharing ratio increased. That is, each cylinder of the cylinder group connected to the specific exhaust purification catalyst is operated with a smaller output than each cylinder of the other cylinder group. In the first operation mode, since the operation of each cylinder is continued even in the cylinder group in which the output sharing ratio is reduced, a decrease in the catalyst temperature when the cylinder is deactivated is suppressed.

  Note that the output of each cylinder of the cylinder group with the reduced output sharing ratio at this time can be set relatively freely regardless of the required output of the internal combustion engine. Therefore, in such a cylinder, it is possible to perform the minimum necessary combustion as long as the temperature reduction of the exhaust purification catalyst can be suppressed. In this case, fuel consumption in such cylinders is kept to a minimum, and a fuel efficiency improvement effect equivalent to the case where a part of the cylinders are substantially deactivated while maintaining the operation of all the cylinders can be obtained.

Therefore, according to the above configuration, it is possible to more effectively achieve both fuel efficiency and exhaust purification performance.
According to a second aspect of the present invention, in the first aspect of the present invention, the exhaust gas purification connected to the cylinder group in which the output share ratio of each cylinder in the first operation mode is reduced. The gist is to variably set according to the temperature of the catalyst.

According to the above configuration, since the output sharing ratio is set according to the temperature of the exhaust purification catalyst, it is possible to more reliably and efficiently suppress the decrease in the catalyst temperature.
The invention according to claim 3 is the invention according to claim 1 or 2, wherein in the first operation mode, a cylinder group in which an output sharing ratio of each cylinder is reduced is set between the plurality of cylinder groups. The gist is to switch sequentially.

  For example, when the output sharing ratio of each cylinder is reduced only in some specific cylinder groups in the first operation mode, the temperature of only the exhaust purification catalyst connected to the cylinder group is likely to decrease. Situation. For example, it is conceivable to switch the operation mode to the second operation mode in order to avoid such an excessive temperature drop. However, if the switching to the second operation mode is frequently performed, the fuel consumption performance is improved. There is a concern that it becomes difficult to achieve both the fuel efficiency and the exhaust purification performance.

  In that respect, according to the present invention, since the cylinder group whose output sharing ratio is reduced is sequentially switched between the plurality of cylinder groups, the frequency of switching to the second operation mode as described above is suppressed. An excessive temperature drop in some specific exhaust purification catalysts can be prevented, and it is possible to effectively achieve both fuel efficiency and exhaust purification performance.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the engine operation in the first operation mode is performed on condition that the operation is a low load operation. The gist.

  Since the required output of the internal combustion engine is small during low load operation, the required output can be relatively easily ensured in other cylinder groups even if the output sharing ratio of each cylinder in some cylinder groups is low. Therefore, according to the present invention, it is possible to extremely reduce the output of each cylinder of the cylinder group whose output sharing ratio is reduced, and the fuel efficiency can be improved more reliably.

  The gist of the invention according to claim 5 is that, in the invention according to any one of claims 1 to 4, the engine operation is performed in the first operation mode on condition that the engine is started. And

  According to the above configuration, for example, the temperature of some of the specific exhaust purification catalysts can be intensively raised, so that the exhaust purification performance after engine startup can be improved earlier. For example, by adopting the configuration of the invention described in claim 3 above, it becomes possible to sequentially raise the temperature of the plurality of exhaust purification catalysts.

  In addition, as a configuration for adjusting the output sharing ratio described above, for example, according to the invention according to claim 6, in the invention according to any one of claims 1 to 5, the internal combustion engine includes: A variable valve mechanism for varying the maximum lift amount of the intake valve of each cylinder is provided, and adjustment of the output share ratio of each cylinder in the first operation mode is performed by adjusting each cylinder of the cylinder group whose output share ratio is reduced. The maximum lift amount of the intake valve can be controlled by controlling the variable valve mechanism so as to be reduced as compared with each cylinder of the other cylinder group. According to this, it is possible to adjust the output sharing ratio of each cylinder more easily and accurately.

  Hereinafter, an embodiment in which the present invention is embodied in a control device for a V-type six-cylinder gasoline internal combustion engine mounted on an automobile will be described with reference to FIGS. FIG. 1 is a schematic configuration diagram of the internal combustion engine, and FIG. 2 is a diagram showing only one cylinder of the internal combustion engine and showing a control system and the like in the present control device.

  The internal combustion engine 11 of the present embodiment includes first to sixth cylinders # 1 to # 6. Of these cylinders # 1 to # 6, the first cylinder group G1 composed of cylinders # 1, # 3, and # 5 is placed in the first bank B1 of the internal combustion engine 11 and the remaining three cylinders # 2, # 4, and # 6. The second cylinder group G2 is provided in the second bank B2.

  Air is sucked into the combustion chambers 12 of the cylinders # 1 to # 6 through the intake passage 13 and fuel is injected from the fuel injection valve 14. When the air-fuel mixture is ignited by the spark plug 15, the air-fuel mixture burns, the piston 16 reciprocates, and the crankshaft 17 that is the engine output shaft rotates.

  The air-fuel mixture after combustion is sent out from each combustion chamber 12 to the exhaust passage 18 as exhaust gas. The exhaust passage 18 has a first branch portion 18a and a second branch portion 18b individually formed so as to correspond to the cylinder groups G1 and G2, respectively, on the upstream side thereof. The exhaust gas discharged from the combustion chamber 12 is sent to the first branch portion 18a, and the exhaust gas discharged from each combustion chamber 12 of the second cylinder group G2 is sent to the second branch portion 18b.

  A first exhaust purification catalyst 19A is provided in the first branch portion 18a of the exhaust passage 18, and a second exhaust purification catalyst 19B is provided in the second branch portion 18b. Each of these exhaust purification catalysts 19A and 19B is composed of a three-way catalyst, the first exhaust purification catalyst 19A is exhaust gas discharged from each combustion chamber 12 of the first cylinder group G1, and the second exhaust purification catalyst 19B is second. The exhaust gas discharged from each combustion chamber 12 of the cylinder group G2 is purified. The exhaust gas thus purified is released into the atmosphere via the downstream side of the exhaust passage 18. That is, the cylinder groups G1 and G2 are connected to different exhaust purification catalysts 19A and 19B through the exhaust passage 18, respectively.

  In the internal combustion engine 11, the combustion chambers 12 and the intake passages 13 are communicated and blocked by the opening / closing operation of the intake valves 21, and the combustion chambers 12 and the exhaust passages 18 are communicated / blocked by the opening / closing operations of the exhaust valves 22. Is done. The intake valve 21 and the exhaust valve 22 open and close in accordance with the rotation of the intake camshaft 23 and the exhaust camshaft 24 to which the rotation of the crankshaft 17 is transmitted.

  Between the intake camshaft 23 and the intake valve 21, there are variable valve mechanisms 31 for varying the maximum lift amount of the valve 21 and the operating angle (that is, the operating angle of the intake cam 23a for opening and closing the intake valve 21). It is provided individually for each of the cylinders # 1 to # 6. An actuator 32 composed of an electric motor for driving each variable valve mechanism 31 is individually provided for each of the banks B1, B2, that is, each of the cylinder groups G1, G2, and each variable valve mechanism 31 is common to each. The cylinders G1 and G2 are driven via the drive shaft 33. In this embodiment, such a configuration allows the maximum lift amount and the operating angle to be changed individually for each of the cylinder groups G1 and G2 through driving of the variable valve mechanisms 31 by the actuators 32. Yes.

  FIG. 3 shows how the maximum lift amount and the operating angle are changed by driving the variable valve mechanism 31. As can be seen from the characteristic curve shown in the figure, the maximum lift amount and the operating angle change in synchronization with each other. For example, the maximum lift amount decreases as the operating angle decreases. The fact that the operating angle becomes smaller means that the opening timing and closing timing of the intake valve 21 are close to each other, and that the opening period of the intake valve 21 is shortened. In the present embodiment, the maximum lift amount and the operating angle can be continuously changed between the characteristic curves shown in FIG.

  In the present embodiment through the variable valve mechanism 31, the adjustment of the amount of air sucked into the combustion chamber 12 (intake air amount adjustment) is performed by adjusting the maximum lift amount and the operating angle according to the engine operating state such as the load of the internal combustion engine 11. This is performed based on the variable control. That is, for example, by reducing the maximum lift amount and the operating angle through the variable control, the amount of air taken into the combustion chamber 12 is reduced.

  In the present embodiment, output adjustment of the internal combustion engine 11 is performed based on such intake air amount adjustment performed through the variable valve mechanism 31. In the present internal combustion engine 11, since the intake air amount adjustment through the variable valve mechanism 31 can be performed individually for each cylinder group G1, G2, the output adjustment is performed for each cylinder group G1, G2. Can be performed individually.

  As shown in FIGS. 1 and 2, in the internal combustion engine 11 of the present embodiment, a throttle valve 41 is provided in the middle of the intake passage 13, and the intake air amount is adjusted by adjusting the opening of the valve 41. It is also possible.

The internal combustion engine 11 having such a configuration is controlled by the electronic control unit 51.
A signal corresponding to the stop request operation and the start request operation of the internal combustion engine 11 is input to the electronic control unit 51 from an ignition switch 52 operated by a driver of the automobile. Further, the electronic control unit 51 calculates the flow rate of intake air (total intake air amount) in the intake passage 13 based on a signal from an air flow meter 53 provided in the intake passage 13. Further, the temperatures (catalyst temperatures T) of the exhaust purification catalysts 19A and 19B are calculated based on signals from the catalyst temperature sensors 54A and 54B individually provided in the branch portions 18a and 18b of the exhaust passage 18. In addition to the above-described signals, the electronic control device 51 receives detection signals related to the rotational speed of the crankshaft 17, the temperature of the coolant of the internal combustion engine 11, the amount of depression of the accelerator pedal operated by the driver, and the like.

  Based on the information obtained from these signals, the electronic control unit 51 controls the fuel injection of the fuel injection valve 14, the ignition timing control of the ignition plug 15, the variable control of the maximum lift amount and the operating angle through the actuator 32, the throttle valve. 41 is controlled.

Next, a characteristic configuration of the present embodiment will be described.
In this embodiment, through the electronic control unit 51, for example, during the low load operation of the internal combustion engine 11, the operation of each cylinder in one of the two cylinder groups G1, G2 is maintained while maintaining the operation of all the cylinders # 1 to # 6. The output sharing rate R is made smaller than the output sharing rate R of each cylinder of the other cylinder group, so that the exhaust amount of the internal combustion engine 11 is substantially reduced, thereby improving the fuel consumption. More specifically, the internal combustion engine 11 is switched between the first operation mode in which the output share ratio R is reduced and the second operation mode in which the output share ratios R of all the cylinders # 1 to # 6 are equalized. I am trying to drive. The “output sharing ratio R” indicates the ratio of the output of each cylinder # 1 to # 6 to the required output of the internal combustion engine 11, that is, the sum of the outputs of all cylinders # 1 to # 6.

  Hereinafter, the procedure of such operation mode switching processing will be described with reference to the flowchart shown in FIG. A control routine relating to this processing is executed through the electronic control unit 51 by, for example, a time interruption every predetermined time.

  In this control routine, first, it is determined whether the internal combustion engine 11 is being started (when the engine is started) or whether the internal combustion engine 11 is operating at a low load (when the engine is operating at a low load). Is performed (step S110). Whether or not the engine is starting is determined based on a signal corresponding to the start request operation issued from the ignition switch 52. Whether or not the low load operation is being performed is determined based on a signal relating to the total intake air amount of the internal combustion engine 11 reflecting the engine load, that is, a detection signal from the air flow meter 53, a signal relating to the depression amount of the accelerator pedal, or the like. Based on the determination.

  If it is determined that the engine is starting or operating at a low load (step S110: YES), the engine is operated in the first operation mode (step S120). On the other hand, when it is determined that the engine is neither at the time of engine start nor at the time of low load operation, that is, at the time of medium load operation or high load operation (step S110: NO), the engine in the second operation mode is determined. Operation is performed (step S130).

  In the second operation mode, the engine operation is performed in a state where the output sharing ratio R is equal for all the cylinders # 1 to # 6. That is, in this operation mode, the intake air amount is adjusted through the variable valve mechanism 31 so that all the cylinders # 1 to # 6 of the internal combustion engine 11 are operated with equal output (that is, the maximum lift amount and operating angle of the intake valve 21 are variable). Control).

  In this embodiment, since each cylinder group G1, G2 is composed of the same number (three) of cylinders, the sum of the output sharing ratio R in each cylinder group G1, G2 is equal to each other (the value of the output sharing ratio R). 3 times). That is, an output having the same magnitude (50% of the total output of all cylinders # 1 to # 6) is generated from each cylinder group G1, G2.

  On the other hand, in the first operation mode, while the operation of all cylinders # 1 to # 6 is maintained, the output sharing ratio R of each cylinder in one of the two cylinder groups G1 and G2 is reduced, and accordingly, in the other cylinder group. The engine is operated with the output sharing ratio R of each cylinder increased. That is, in this operation mode, the intake air amount adjustment through the variable valve mechanism 31 (that is, the maximum lift) is performed so that each cylinder of one cylinder group is operated with a smaller output than each cylinder of the other cylinder group. Variable control of quantity and operating angle). In the first operation mode, since the operation of each cylinder is continued even in the cylinder group in which the output sharing ratio R is reduced, the decrease in the catalyst temperature T when the cylinder is deactivated is suppressed.

  Further, in the present embodiment, the output sharing ratio R of each cylinder # 1 to # 6 in the first operation mode is connected to the cylinder group on the side where the output sharing ratio R is reduced through the electronic control unit 51. The exhaust purification catalyst is variably set according to the temperature T of the exhaust purification catalyst. The setting of the output sharing ratio R is performed based on the relationship between the output sharing ratio R and the catalyst temperature T as exemplified in FIG. This figure relates to the output sharing ratio R of each cylinder in the cylinder group on the side where the output sharing ratio R is reduced in the first operation mode, and the temperature T of the exhaust purification catalyst connected to the cylinder group.

  The value Ra shown in the figure is the minimum value in the variable setting range of the output sharing ratio R, and the value Rb is the maximum value. That is, for each cylinder whose output sharing ratio R is reduced, the output sharing ratio R is variably set between the minimum value Ra and the maximum value Rb. Therefore, when the output sharing ratio R of each cylinder is set to the minimum value Ra, the sum of the output sharing ratios R in the cylinder group to which each cylinder belongs is three times the minimum value Ra (hereinafter this value is referred to as the minimum sum). (Referred to as ΣRa). Further, when the output sharing ratio R of each cylinder is set to the maximum value Rb, the sum of the output sharing ratios R in the same cylinder group is three times the maximum value Rb (hereinafter this value is referred to as the maximum sum ΣRb). It becomes.

  As described above, the output sharing ratio R is the ratio of the outputs of the cylinders # 1 to # 6 to the sum of the outputs of all the cylinders # 1 to # 6. Therefore, for example, if the operation mode is the second operation mode. For example, the sum of the output sharing ratio R in each of the cylinder groups G1 and G2 is 50%. On the other hand, in the first operation mode, since the output sharing ratio R of each cylinder in one cylinder group is made smaller than in the second operation mode, the maximum sum ΣRb is less than 50%. It will be set smaller. In the present embodiment, the maximum value Rb of the output sharing ratio R of each cylinder in one cylinder group is set so that the maximum sum ΣRb is 40%, for example. That is, in the present embodiment, when the operation mode is the first operation mode, the sum of the output share ratios R of the cylinder group whose output share ratio R is reduced is the output share ratio of each cylinder group in the second operation mode. The value is at least 10% smaller than the total sum of R.

  Further, the minimum sum ΣRa is set to be larger than 0% so that the operation of each cylinder whose output sharing ratio R is reduced is maintained. In this embodiment, the minimum value Ra of the output sharing ratio R of each cylinder is set so that the minimum sum ΣRa is, for example, 10%.

  As shown in the figure, the output sharing ratio R is the maximum value Rb when the catalyst temperature T is equal to or lower than the value Ta, is set to the minimum value Ra when the catalyst temperature T is equal to or higher than the value Tb, and ranges from the value Ta to the value Tb. In this region, the catalyst temperature T is set so as to gradually decrease from the maximum value Rb toward the minimum value Ra as the catalyst temperature T increases. Here, the value Ta is the lower limit value of the active region of the catalyst temperature T in each exhaust purification catalyst 19A, 19B, and the value Tb (> value Ta) is a predetermined value that stabilizes the exhaust purification performance in the exhaust purification catalyst 19A, 19B. Temperature.

  That is, in this embodiment, when the temperature T of the exhaust purification catalyst connected to the cylinder group whose output sharing ratio R is reduced is in a range lower than the active range, the output sharing ratio R is set to the maximum value Rb, and the catalyst When the temperature T is in a region where stable exhaust purification performance is exhibited, the output sharing ratio R is set to the minimum value Ra. When the catalyst temperature T is between the value Ta and the value Tb, the output sharing ratio R gradually decreases from the maximum value Rb toward the minimum value Ra as the catalyst temperature T increases. Is set to Therefore, when the catalyst temperature T is low, the output share ratio R of each cylinder in the cylinder group on the side where the output share ratio R is reduced in the first operation mode is set to be relatively large, so that the cylinder group The temperature rise of the connected exhaust purification catalyst can be promoted, that is, the exhaust purification performance of the exhaust purification catalyst can be suppressed as much as possible.

  Further, in the present embodiment, in the first operation mode, as described above, the output sharing ratio R of each cylinder in one of the two cylinder groups G1, G2 is reduced, and accordingly, each cylinder in the other cylinder group is reduced accordingly. Is increased. That is, when the sum of the output sharing ratio R in the cylinder group whose output sharing ratio R is reduced is the maximum sum ΣRb, the sum of the output sharing ratio R in the other cylinder group is 100% of the maximum sum ΣRb. When the maximum sum ΣRb is 40%, for example, when the maximum sum ΣRb is 40%, it is 60%. Conversely, when the sum of the output sharing ratio R in the cylinder group whose output sharing ratio R is reduced to the minimum sum ΣRa, the total sum of the output sharing ratio R in the other cylinder group is the minimum sum ΣRa. A value obtained by subtracting from 100%, that is, a large value such as 90% when the minimum sum ΣRa is 10%, for example.

  By increasing the output sharing ratio R of each cylinder in the other cylinder group as described above, for example, it is possible to intensively raise the temperature of some specific exhaust purification catalysts. To be able to increase.

  When starting the engine where the catalyst temperature T will be particularly low, the value of the output sharing ratio R of each cylinder of the cylinder group in which the output sharing ratio R is reduced in the first operation mode is set to the minimum value Ra, for example. Accordingly, the degree of increase in the output sharing ratio R of each cylinder in the other cylinder group may be increased accordingly. As a result, it is possible to further accelerate the temperature increase of the exhaust purification catalyst on the side where the output sharing ratio R of each cylinder is increased.

  In the present embodiment, the cylinder group in which the output sharing ratio R of each cylinder is reduced in the first operation mode is sequentially switched between the two cylinder groups G1 and G2 through the electronic control unit 51.

  For example, when the output sharing ratio R of each cylinder is reduced in only one of the two cylinder groups G1 and G2 in the first operation mode, only the exhaust purification catalyst connected to the cylinder group thereby has its catalyst temperature T. Is likely to drop. For example, it is conceivable to switch the operation mode to the second operation mode in order to avoid such an excessive temperature drop. However, if the switching to the second operation mode is frequently performed, the fuel consumption performance is improved. There is a concern that it becomes difficult to achieve both the fuel efficiency and the exhaust purification performance.

  That is, in the present embodiment, as described above, the cylinder group whose output sharing ratio R is reduced is sequentially switched between the two cylinder groups G1 and G2, thereby suppressing the frequency of switching to the second operation mode. Thus, an excessive temperature drop in the exhaust purification catalyst connected to the cylinder group whose output sharing ratio R is reduced is prevented. This makes it possible to achieve both fuel efficiency and exhaust purification performance.

  In the present embodiment, the above-described cylinder switching is performed at a predetermined constant cycle. That is, in a state where the operation mode is set to the first operation mode, the cylinder group whose output sharing ratio R is reduced is switched between both the cylinder groups G1 and G2 at regular intervals.

Next, an example of the above-described control mode through the electronic control unit 51 will be described with reference to the timing chart of FIG.
As shown in the figure, when the internal combustion engine 11 is started based on the operation of the IG switch 52 at the timing t1, the operation mode is set to the first operation mode accordingly, and both cylinder groups G1, G2 are set. The output sharing ratio R of each cylinder in one of the cylinders is reduced. Such a “state in which the operation mode is set to the first operation mode” is maintained as long as the engine operation state is the low load operation state (during the low load operation) (between timings t1 to t6).

  In the present embodiment, first, the second cylinder group G2 connected to the second exhaust purification catalyst 19B is targeted for reduction of the output sharing ratio R (between timings t1 and t2). Then, this reduction target is alternately switched between the cylinder groups G1 and G2 at predetermined intervals. That is, for example, when the predetermined period of time elapses from timing t1, the output sharing rate R reduction target is switched from the second cylinder group G2 to the first cylinder group G1 (timing t2).

  In the period from the timing t1 to the timing t2, the total of the output sharing ratio R in the second cylinder group G2 is smaller than 50% (for example, 40 to 10%), and accordingly, the first cylinder group. The intake air amount adjustment through the variable valve mechanism 31 is performed so that the sum of the output share ratios R in G1 is larger than 50% (for example, 60 to 90%). Thereby, in the said period, the catalyst temperature T of the 1st exhaust purification catalyst 19A rises more rapidly than that of the 2nd exhaust purification catalyst 19B.

  In the period from timing t2 to t3, the cylinder group for which the output sharing ratio R is to be reduced is the first cylinder group G1, and therefore the total output sharing ratio R in the first cylinder group G1 is smaller than 50%. The intake air amount is adjusted to be (for example, 40 to 10%). Similarly to the above, the intake air amount is adjusted so that the sum of the output sharing ratio R in the second cylinder group G2 is larger than 50% (for example, 60 to 90%). Accordingly, during the above period, the catalyst temperature T of the first exhaust purification catalyst 19A is decreasing, and conversely, the catalyst temperature T of the second exhaust purification catalyst 19B is increasing.

  Thereafter, when the engine is operating in the first operation mode, switching of the cylinder group that is a target of reduction of the output sharing ratio R, such as a period from timing t3 to t4 and a period from timing t4 to t5. Is repeated. By switching the cylinder group and setting the output sharing ratio R according to the catalyst temperature T, the catalyst temperature T of each of the exhaust purification catalysts 19A and 19B is good without being below the lower limit value Ta of the active region. It changes with height.

  When the engine operation state shifts from the low load operation state to the medium / high load operation state, the operation mode is switched from the first operation mode to the second operation mode, and the output sharing ratio R is set to all cylinders # 1 to # 1. The intake air amount is adjusted through the variable valve mechanism 31 so as to be equal at # 6 (period after timing t6).

In the present embodiment, the following effects can be obtained.
(1) In the present embodiment, the output sharing ratio R of each cylinder in one of the two cylinder groups G1, G2 is set to the output of each cylinder of the other cylinder group while maintaining the operation of all cylinders # 1 to # 6. The engine operation is performed while switching between a first operation mode that is smaller than the sharing ratio R and a second operation mode in which the output sharing ratios R of all the cylinders # 1 to # 6 are equal. That is, in the first operation mode, each cylinder of the cylinder group connected to the specific exhaust purification catalyst is operated with a smaller output than each cylinder of the other cylinder group. Further, in this first operation mode, since the operation of each cylinder is continued even in the cylinder group in which the output sharing ratio R is reduced, the decrease in the catalyst temperature T as in the case of cylinder deactivation is suppressed. Become.

  Note that the output of each cylinder of the cylinder group in which the output sharing ratio R is reduced at this time can be set relatively freely regardless of the required output of the internal combustion engine 11. Therefore, in such a cylinder, it is possible to perform the minimum necessary combustion as long as the temperature reduction of the exhaust purification catalyst connected thereto can be suppressed. In this case, fuel consumption in such cylinders is kept to the minimum necessary, and an effect of improving fuel consumption is obtained in accordance with a case where a part of the cylinders are substantially deactivated while maintaining the operation of all cylinders # 1 to # 6. Be able to.

Therefore, according to the present embodiment, it becomes possible to achieve both the fuel efficiency performance and the exhaust purification performance more effectively.
(2) The output sharing ratio R of each cylinder in the first operation mode is variably set according to the catalyst temperature T of the exhaust purification catalyst connected to the cylinder group in which the output sharing ratio R is reduced. According to this, since the output sharing ratio R according to the catalyst temperature T is set, the fall of the catalyst temperature T can be more reliably and efficiently suppressed.

  (3) In the first operation mode, the cylinder group whose output sharing ratio R is reduced is sequentially switched between the two cylinder groups G1, G2. According to this, for example, unlike the case where the cylinder group whose output sharing ratio R is reduced is fixed to a specific one, it is possible to prevent an excessive temperature drop in some specific exhaust purification catalysts, It becomes possible to effectively achieve both fuel efficiency and exhaust purification performance.

  (4) The engine operation in the first operation mode is performed on the condition that it is during low load operation. During low load operation, the required output of the internal combustion engine 11 is small, so even if the output sharing ratio R of each cylinder in one of the two cylinder groups G1, G2 is low, the required output is relatively easily secured in the other cylinder group. it can. Therefore, according to this embodiment, the output of each cylinder of the cylinder group whose output sharing ratio R is reduced can be made extremely small, and the fuel efficiency can be improved more reliably.

  (5) The engine operation in the first operation mode is performed on the condition that the engine is starting. According to this, for example, since one of the two exhaust purification catalysts 19A and 19B can be intensively heated, the exhaust purification performance after starting the engine can be improved earlier. Further, in the present embodiment, as described above, the cylinder group whose output sharing ratio R is decreased is sequentially switched between the two cylinder groups G1 and G2, so that both the exhaust purification catalysts 19A and 19B are sequentially switched. The temperature can be raised.

In addition, embodiment is not limited above, For example, it is good also as the following aspects.
In the first operation mode, the magnitude of the output sharing ratio R in each cylinder of the cylinder group for which the output sharing ratio R is to be reduced does not necessarily need to be variably set according to the catalyst temperature T. Regardless of the level of the catalyst temperature T, it may be always constant.

  In the timing chart of FIG. 6, when the operation mode of the internal combustion engine 11 is set to the first operation mode, the second cylinder group G2 is first targeted for reduction in the output sharing ratio R. Not limited to this, the first cylinder group G1 may be a target for reducing the output sharing ratio R first.

  In the embodiment described above, the switching of the cylinder group to be reduced in the output sharing ratio R in the first operation mode is performed at a preset constant cycle, but is not limited thereto, for example, the catalyst temperature T or the like It may be performed in a cycle variably set according to the above.

In the first operation mode, switching of the cylinder group that is the target for reducing the output sharing ratio R is not necessarily performed.
In the above embodiment, the condition for engine operation in the first operation mode is “being at engine start or low load operation”, but is not limited to this, for example, “at full load operation” May not be adopted. It should be noted that it is not always necessary to adopt “being in a specific engine operating state” as the above condition.

  In the above embodiment, the engine output adjustment in the engine operation in the first and second operation modes is performed through variable control of the maximum lift amount and the operating angle of the intake valve 21, but not limited thereto, for example, A separate intake passage may be connected to each of the cylinder groups G1 and G2, and a throttle valve may be individually provided in each intake passage, and the opening control may be performed.

  The present invention may be applied to a diesel internal combustion engine. In this case, the output relating to the engine operation in the first operation mode or the second operation mode is adjusted through adjustment of the fuel injection amount.

  In the above embodiment, the present invention is applied to the internal combustion engine 11 having the two cylinder groups G1 and G2. However, the present invention is not limited to this, and may be applied to an engine having three or more cylinder groups. Further, the arrangement of the cylinder groups is not limited to an aspect in which each cylinder group is provided for each of the banks B1 and B2 in the V-type internal combustion engine 11 as in the above embodiment, for example, a plurality of cylinder groups arranged in series. A mode in which the cylinders are divided into a plurality of cylinder groups may be employed. The number of cylinders may be different for each cylinder group.

1 is a schematic configuration diagram of an internal combustion engine of an embodiment. The figure which shows the control system etc. in this control apparatus, showing only one cylinder of an internal combustion engine. The figure which shows the relationship between the lift amount of an intake valve, and an operating angle. The flowchart about the procedure of the operation mode switching process performed through an electronic controller. The figure which shows an example of the setting aspect in the variable setting of the output sharing rate according to a catalyst temperature. The timing chart for demonstrating the example of the control of one Embodiment through an electronic control apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Internal combustion engine, 19A ... 1st exhaust purification catalyst, 19B ... 2nd exhaust purification catalyst, 21 ... Intake valve, 31 ... Variable valve mechanism, 51 ... Electronic control unit, G1 ... 1st cylinder group, G2 ... 2nd cylinder Group, R ... output sharing ratio, T ... catalyst temperature, # 1, # 2, # 3, # 4, # 5, # 6 ... cylinder.

Claims (6)

A control device for an internal combustion engine having a plurality of cylinder groups each connected to a different exhaust purification catalyst,
A first operation mode in which the output sharing ratio of each cylinder of any cylinder group is made smaller than the output sharing ratio of each cylinder of the other cylinder group while maintaining the operation of all cylinders, A control device for an internal combustion engine, wherein the engine operation is performed while switching between a second operation mode in which the output sharing ratio is uniform. 2. The internal combustion engine according to claim 1, wherein an output sharing ratio of each cylinder in the first operation mode is variably set according to a temperature of an exhaust purification catalyst connected to a cylinder group whose output sharing ratio is reduced. Control device. 3. The control device for an internal combustion engine according to claim 1, wherein, in the first operation mode, a cylinder group in which an output sharing ratio of each cylinder is reduced is sequentially switched between the plurality of cylinder groups. The control device for an internal combustion engine according to any one of claims 1 to 3, wherein the engine operation is performed in the first operation mode on condition that the operation is in a low load operation. The internal combustion engine control device according to any one of claims 1 to 4, wherein the engine is operated in the first operation mode on condition that the engine is started. In the control device for an internal combustion engine according to any one of claims 1 to 5,
The internal combustion engine includes a variable valve mechanism that varies the maximum lift amount of the intake valve of each cylinder,
The adjustment of the output sharing ratio of each cylinder in the first operation mode is performed by comparing the maximum lift amount of the intake valve of each cylinder of the cylinder group in which the output sharing ratio is reduced with respect to each cylinder of the other cylinder group. The control apparatus for an internal combustion engine, wherein the control is performed by controlling the variable valve mechanism so as to be reduced.

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