JP2021006720A - Combusting-cylinder ratio variation control apparatus - Google Patents

Abstract

To provide a combusting-cylinder ratio variation control apparatus capable of suppressing variation in an engine revolution associated with a change in cylinder deactivation intervals in performing the variation control of a combusting-cylinder ratio.SOLUTION: A combusting-cylinder ratio variation control unit 11, for use in variation control of a combusting-cylinder ratio of an engine 10 during an intermittent deactivation operation performing an intermittent cylinder deactivation, includes a target combusting-cylinder ratio computation part 13 and a cylinder deactivation pattern determination part 14. The target combusting-cylinder ratio computation part 13 calculates, as a target combusting-cylinder ratio, a combusting-cylinder ratio that can be realized by repeating cylinder deactivation at a constant interval. In a case where a present combusting-cylinder ratio is consistent with the target combusting-cylinder ratio, the cylinder deactivation pattern determination part 14 sets, as a cylinder deactivation pattern to be executed next, a pattern with which cylinder deactivation pattern can realize the target cylinder deactivation interval, whereas in a case where the aforementioned consistency is absent, the cylinder deactivation pattern determination part sets a pattern with which a cylinder deactivation interval becomes shorter than the present cylinder deactivation interval by one cylinder so as to realize the target combusting-cylinder ratio.SELECTED DRAWING: Figure 1

Description

The present invention relates to a technique for variably controlling the combustion cylinder ratio of an engine during intermittent pause operation in which cylinders are paused intermittently.

The method described in Patent Document 1 is known as a method for variably controlling the combustion cylinder ratio [= number of combustion cylinders / (number of combustion cylinders + number of rest cylinders)] as described above. In this document, various combustion cylinder ratios are realized by not fixing the cylinders that perform combustion and the cylinders that stop combustion.

U.S. Pat. No. 9,200,755

In the above document, as an example of a cylinder suspension pattern that realizes a predetermined combustion cylinder ratio, combustion of one cylinder is paused after continuously burning five cylinders, and then combustion is performed by one cylinder, and then 1 It is described that the combustion cylinder ratio is set to 0.75 (= 6/8) by performing cylinder suspension in a pattern of suspending combustion of cylinders. In this cylinder deactivation pattern, there are a section where the cylinder deactivation interval is for 5 cylinders and a section where the same interval is for 1 cylinder.

The engine speed drops once in response to cylinder deactivation, but the amount of increase in engine speed thereafter increases in the section where the cylinder deactivation interval is long, and decreases in the section where the same interval is short. Therefore, if a section having a long cylinder deactivation interval and a section having a short cylinder deactivation interval are mixed, the engine rotation fluctuation becomes large. In order to suppress such engine rotation fluctuations, individual torque management for each cylinder is required. That is, it is necessary to increase the torque generation amount of each cylinder that burns in the section where the cylinder deactivation interval is short as compared to the section where the same interval is long, and to make the amount of increase in the engine speed until the next cylinder deactivation uniform.

Further, when the combustion cylinder ratio is variably controlled, the cylinder deactivation pattern changes according to the change of the ratio. Therefore, individual torque management for each cylinder to suppress rotational fluctuation becomes complicated.

The present invention has been made in view of these circumstances, and the problem to be solved is to suppress fluctuations in engine rotation due to changes in cylinder deactivation intervals when variable control of the combustion cylinder ratio is performed. ..

A variable control device for the combustion cylinder ratio that solves the above problems is a variable control device for the combustion cylinder ratio that performs variable control of the combustion cylinder ratio of the engine during intermittent pause operation in which cylinder suspension is performed intermittently, at regular intervals. The target combustion cylinder ratio calculation unit that calculates the combustion cylinder ratio that can be realized by repeating cylinder suspension as the target combustion cylinder ratio, and the cylinder suspension at intervals that realize the current combustion cylinder ratio, and then the cylinder suspension is performed. When the interval between cylinder suspensions up to is the next suspension interval, and the target combustion cylinder ratio and the current combustion cylinder ratio match, the interval at which the target combustion cylinder ratio can be realized is defined as the next suspension interval. When the target combustion cylinder ratio and the current combustion cylinder ratio do not match, the interval of one cylinder closer to the interval at which the target combustion cylinder ratio can be realized than the interval at which the current combustion cylinder ratio is realized is paused next time. It is equipped with a cylinder suspension pattern determination unit for intervals.

When the next pause interval is set in this way, the cylinder pause interval is kept constant while the combustion cylinder ratio is constant, and even when the combustion cylinder ratio is changed, the cylinder pause interval is one cylinder at a time. Will only change. Therefore, according to the variable control device, it is possible to suppress fluctuations in engine rotation due to changes in the cylinder deactivation interval when variable control of the combustion cylinder ratio is performed.

The figure which shows typically the structure of 1st Embodiment of the variable control device of a combustion cylinder ratio. The graph which shows the relationship between the target combustion cylinder ratio calculated by the target combustion cylinder ratio calculation unit provided in the said variable control device, the required torque, and the engine speed. The flowchart of the cylinder deactivation pattern determination routine executed by the cylinder deactivation pattern determination unit provided in the said variable control device. A time chart showing an example of an embodiment of variable control of the combustion cylinder ratio according to the same embodiment. The figure which shows typically the structure of the 2nd Embodiment of the variable control device of a combustion cylinder ratio. The graph which shows the relationship between the target combustion cylinder ratio calculated by the target combustion cylinder ratio calculation unit provided in the said variable control device, the required torque, and the engine speed.

(First Embodiment)
Hereinafter, the variable control method of the combustion cylinder ratio and the first embodiment of the variable control device will be described in detail with reference to FIGS. 1 to 4. Here, first, the configuration of the variable control device of the same embodiment will be described with reference to FIG.

The engine 10 shown in FIG. 1 includes four cylinders # 1 to # 4 arranged in series. The firing order of cylinders # 1 to # 4 in the engine 10 is in the order of cylinder # 1, cylinder # 3, cylinder # 4, and cylinder # 2.

The engine 10 is controlled by the electronic control unit 11. Detection signals such as engine speed and intake air amount detected by various sensors installed in the engine 10 are input to the electronic control unit 11. Then, the electronic control unit 11 controls the throttle opening degree, the fuel injection timing, the fuel injection amount, the ignition timing, and the like of the engine 10 based on the detection signals.

Further, the electronic control unit 11 includes a combustion cylinder ratio variable control unit 12 that performs variable control of the combustion cylinder ratio of the engine 10. The combustion cylinder ratio variable control device of the present embodiment is composed of the combustion cylinder ratio variable control unit 12. The combustion cylinder ratio represents the ratio of the number of combustion cylinders to the total number of combustion cylinders and rest cylinders [= number of combustion cylinders / (number of combustion cylinders + number of rest cylinders)], and variable control of the combustion cylinder ratio is such an engine 10. It is controlled to change the combustion cylinder ratio of the engine 10 according to the output request of the engine 10.

The combustion cylinder ratio variable control unit 12 is based on the target combustion cylinder ratio calculation unit 13 that calculates the target combustion cylinder ratio, which is the target value of the combustion cylinder ratio, and the engine based on the target combustion cylinder ratio, according to the operating state of the engine 10. It is provided with a cylinder suspension pattern determining unit 14 for determining a cylinder suspension pattern of 10. Then, the combustion cylinder ratio variable control unit 12 controls the engine 10 so that the cylinder deactivation is performed according to the determined cylinder deactivation pattern.

(Determination of target combustion cylinder ratio)
Here, the calculation of the target combustion cylinder ratio by the target combustion cylinder ratio calculation unit 13 will be described. The target combustion cylinder ratio calculation unit 13 requests the engine 10 obtained from the engine speed (hereinafter referred to as the engine speed) and the amount of depression of the accelerator pedal of the driver for each specified control cycle. While reading the torque, the target combustion cylinder ratio is calculated from the required torque and engine speed.

FIG. 2 shows the relationship between the value of the target combustion cylinder ratio calculated by the target combustion cylinder ratio calculation unit 13 and the required torque and the engine speed. As shown in the figure, the target combustion cylinder ratio is calculated so that the value is one of 50%, 67%, 75%, 80%, and 100%.

As shown in the figure, in the present embodiment, the target combustion cylinder ratio is 100% in the operating range of the engine 10 in which the required torque exceeds the default value α and in the operating range of the engine 10 in which the engine speed is lower than the default value β. Is fixed to. When the combustion cylinder ratio is 100%, the engine 10 is operated by all-cylinder combustion in which combustion is performed in all cylinders. In the engine 10 at this time, the required output is realized by adjusting the flow rate of air taken in by the cylinder (cylinder inflow air amount) in the intake stroke. Hereinafter, the operating range of the engine 10 that performs such all-cylinder combustion operation will be referred to as an all-cylinder combustion operating range.

On the other hand, in the operating range where the required torque is equal to or less than the default value α and the engine speed is equal to or higher than the default value β, the target combustion cylinder ratio is changed in the range of 50% to 80% according to the required torque. In such an operating range, cylinder suspension is performed intermittently, and the required output of the engine 10 is realized by adjusting the cylinder inflow air amount and changing the combustion cylinder ratio. Hereinafter, the operating range of the engine 10 that performs such intermittent cylinder deactivation will be referred to as an intermittent deactivation operating range.

By the way, the above-mentioned default value α, which is the threshold value of the required torque that separates the all-cylinder combustion operation range and the intermittent pause operation range, is the maximum value of the engine torque that can be achieved even when the combustion cylinder ratio is 80%. Is set. On the other hand, the following values are set for the value of the above-mentioned default value β, which is the threshold value of the engine speed that separates the all-cylinder combustion operation range and the intermittent pause operation range. That is, in the engine 10 during the intermittent deactivation operation, the engine speed temporarily drops each time the cylinder deactivation is performed, so that vibration and noise are generated with the cylinder deactivation interval as a cycle. When the cylinder deactivation interval is constant, the lower the engine speed, the lower the frequency of vibration and noise associated with cylinder deactivation. On the other hand, occupants tend to feel uncomfortable with vibrations and noises having frequencies lower than a certain level. Therefore, the default value β is set as a lower limit value of the engine speed at which the frequency of vibration or noise due to cylinder deactivation does not become a low frequency that makes the occupant feel uncomfortable.

(Determining cylinder deactivation pattern)
Subsequently, determination of the cylinder deactivation pattern by the cylinder deactivation pattern determination unit 14 will be described. Table 1 shows the order of combustion and deactivation of the cylinders in each of the values of the combustion cylinder ratio used in the variable control of the combustion cylinder ratio. As shown in the table, in the variable control of the combustion cylinder ratio, there are nine types of combustion cylinder ratios of 0%, 50%, 67%, 75%, 80%, 83%, 86%, 88% and 100%. used. Incidentally, in the case of all cylinder deactivation in which combustion is temporarily deactivated in all cylinders such as when fuel is cut or idle stop, the combustion cylinder ratio is 0%.

Of the above nine combustion cylinder ratios, 0% is the ratio in the case of all cylinder deactivation, and 100% is the ratio in the case of all cylinder combustion. Therefore, among the combustion cylinder ratios shown in Table 1, the ratios used during the intermittent pause operation of the engine 10 are 50%, 67%, 75%, 80%, 83%, 86%, and 88%. There are 7 ways. In these combustion cylinder ratios, cylinder deactivation is repeated in a pattern in which N (integer of 1 or more) cylinders are continuously burned in the order of cylinders reaching the combustion stroke and then combustion of one cylinder is stopped. That is, all the combustion cylinder ratios used during the intermittent deactivation operation are ratios that can be realized by repeating the cylinder deactivation of the above pattern, that is, by repeating the cylinder deactivation at regular intervals. Then, the 50%, 67%, 75%, and 80% combustion cylinder ratios calculated by the target combustion cylinder ratio calculation unit 13 as the target combustion cylinder ratio during the intermittent pause operation are also cylinder pauses at regular intervals. It is a combustion cylinder ratio that can be realized by repetition.

In the present embodiment, each of the cylinder deactivation patterns is assigned an identification number (ID) whose value is the number of cylinders (N) that continuously burn in each pattern. Further, in the present embodiment, for the convenience of processing in the cylinder deactivation pattern determination routine described later at the time of transition from all cylinder deactivation operation to intermittent deactivation operation and at the time of transition from all cylinder deactivation operation to intermittent deactivation operation, the combustion cylinder The cases where the ratio is 0% (all cylinders deactivated) and 100% (all cylinders burned) are treated as follows. That is, when the ratio of combustion cylinders in which only cylinder deactivation is repeated is 0% (all cylinder deactivation), a pattern consisting of one cylinder deactivation is used as a convenient cylinder deactivation pattern, and its identification number is set to "0". Further, when the ratio of combustion cylinders in which only combustion is repeated is 100%, a pattern consisting of one combustion is set as a cylinder deactivation pattern for convenience, and the identification number is set to "8".

Further, in the present embodiment, when changing the cylinder deactivation pattern, the cylinder deactivation pattern before the change is performed to the end, and then the cylinder deactivation pattern after the change is started from the beginning. Further, in the present embodiment, the cylinder deactivation pattern is started at the end of the cylinder deactivation pattern before the change, and then the cylinder deactivation pattern after the change is started. Therefore, in each cylinder suspension pattern having the identification numbers 1 to 7, the cylinder corresponding to the end is set to be the suspension cylinder. Further, regarding the cylinder deactivation pattern having the identification number 8 corresponding to the combustion of all cylinders not including the cylinder deactivation, one after burning in one cylinder only immediately before the change to another cylinder deactivation pattern. The pattern is such that the combustion of the cylinder is stopped.

The cylinder deactivation pattern determination unit 14 actually performs any of the cylinder deactivation patterns of the identification numbers 0 to 8 in the engine 10 based on the target combustion cylinder ratio calculated by the target combustion cylinder ratio calculation unit 13. To determine as. FIG. 3 shows a flowchart of a cylinder deactivation pattern determination routine executed by the cylinder deactivation pattern determination unit 14 when determining a cylinder deactivation pattern. The cylinder deactivation pattern determination unit 14 executes the same routine processing for each combustion cycle of the engine 10.

As shown in FIG. 3, when the processing of this routine is started, first, in step S100, the identification number of the cylinder deactivation pattern of the target combustion cylinder ratio calculated by the target combustion cylinder ratio calculation unit 13 (hereinafter referred to as the target pattern Nt). The identification number of the cylinder deactivation pattern currently being performed in the engine 10 (hereinafter, referred to as the pattern Nc) is read. Subsequently, in step S110, it is determined whether or not both the values of the target pattern Nt and the current pattern Nc match. If both values match (YES), the process proceeds to step S120, and if they do not match (NO), the process proceeds to step S130.

When the process proceeds to step S120, the value of the current pattern Nc is set as the value of the next pattern Nn in the step S120. Then, in step S160, as the next cylinder deactivation pattern to be performed after the current cylinder deactivation pattern ends, a cylinder deactivation pattern having the value of the next pattern Nn as an identification number is set, and then the processing of this routine ends. Will be done. That is, in the engine 10 at this time, the cylinder deactivation is performed in the same cylinder deactivation pattern as the present one next time.

On the other hand, if both values of the current pattern Nc and the target pattern Nt do not match (S110: NO) and the process proceeds to step S130, the magnitude relationship between the two values is determined in step S130. .. Then, when the value of the target pattern Nt is larger than the value of the current pattern Nc (S130: YES), the value obtained by adding 1 to the value of the current pattern Nc in step S140 is the value of the next pattern Nn. Is set as (Nn ← Nc + 1). On the other hand, when the value of the target pattern Nt is smaller than the value of the current pattern Nc (S130: NO), in step S150, the value obtained by subtracting 1 from the value of the current pattern Nc is used as the value of the next pattern Nn. It is set (Nn ← Nc-1). Then, in step S160 described above, the processing of this routine is terminated after the cylinder deactivation pattern having the value of the next pattern Nn set in step S140 or step S150 as the identification number is set as the cylinder deactivation pattern to be performed next time. ..

Here, the cylinder deactivation interval from the cylinder deactivation to the next cylinder deactivation at the interval that realizes the current combustion cylinder ratio is described as the next deactivation interval. As described above, each cylinder suspension pattern of the identification numbers 1 to 7 used during the intermittent suspension operation has a cylinder suspension at the end. Therefore, the next deactivation interval corresponds to the number of combustion cylinders in the next cylinder deactivation pattern performed after the current cylinder deactivation pattern ends.

In the cylinder stop pattern determination routine, when the identification number of the cylinder stop pattern (target pattern Nt) corresponding to the target burning cylinder ratio and the identification number of the cylinder stop pattern being executed (current pattern Nc) match (S110: YES). ), The running cylinder pause pattern will continue next time. The case where the target pattern Nt and the current pattern Nc match is the case where the target combustion cylinder ratio and the current combustion cylinder ratio match, and the cylinder pause interval at this time can realize the target combustion cylinder ratio. It is an interval. Therefore, when the target combustion cylinder ratio and the current combustion cylinder ratio match, the cylinder deactivation pattern determination unit 14 sets the cylinder deactivation pattern so that the interval at which the target combustion cylinder ratio can be realized is the next deactivation interval. Will be decided.

On the other hand, when the target pattern Nt and the current pattern Nc do not match (S110: NO), the cylinder deactivation is set to the value obtained by adding or subtracting 1 to the value of the current pattern Nc on the side approaching the target pattern Nt as the identification number. The pattern is the cylinder deactivation pattern to be executed next time. In such a case, the number of combustion cylinders in the next cylinder deactivation pattern is closer to the number of combustion cylinders in the cylinder deactivation pattern that realizes the target combustion cylinder ratio than the number of combustion cylinders in the current cylinder deactivation pattern. That is, the next pause interval at this time is an interval that is closer to one cylinder than the interval at which the current combustion cylinder ratio can be realized.

(Action effect)
Subsequently, the variable control method of the combustion cylinder ratio and the operation and effect of the variable control device of the present embodiment will be described.

FIG. 4 shows the transition of the combustion cylinder ratio, the cylinder deactivation pattern, and the injection signal when the operation range of the engine 10 shifts from the all-cylinder combustion operation range to the region where the target combustion cylinder ratio in the intermittent deactivation operation range is 50%. .. The injection signal is a signal for instructing fuel injection to the cylinder when combustion is performed in the cylinder, and in the figure, the injection signals for the four cylinders # 1 to # 4 of the engine 10 are merged. It is shown. By the way, since the injection signal is not output when the cylinder is deactivated, the portion where the pulse interval of the injection signal shown in the figure is wider than the other portions is the portion where the cylinder is deactivated.

When the target combustion cylinder ratio is changed from 100% to 50%, a cylinder deactivation pattern with an identification number of 7 corresponding to the 88% combustion cylinder ratio is first executed. At this time, the engine 10 switches from the all-cylinder combustion operation to the intermittent pause operation.

After that, in order, the cylinder deactivation pattern with the identification number 6 corresponding to the combustion cylinder ratio of 86%, the cylinder deactivation pattern with the identification number 5 corresponding to the combustion cylinder ratio of 83%, and the combustion cylinder ratio of 80% correspond. A cylinder deactivation pattern with an identification number of 4, a cylinder deactivation pattern with an identification number of 3 corresponding to a 75% combustion cylinder ratio, and a cylinder deactivation pattern with an identification number of 2 corresponding to a 67% combustion cylinder ratio were executed once. Later, the cylinder deactivation pattern is changed to a pattern in which the identification number corresponding to the 50% combustion cylinder ratio, which is the target combustion cylinder ratio at this time, is 1. As described above, in each cylinder deactivation pattern having the identification numbers 1 to 7, the value of the identification number corresponds to the number of cylinders that continuously burn before the cylinder deactivation, that is, the cylinder deactivation interval. Therefore, the change of the combustion cylinder ratio at this time is performed by sequentially changing the cylinder deactivation pattern so that the cylinder deactivation interval changes by one cylinder.

Even when the value of the target combustion cylinder ratio is changed in the intermittent deactivation operation range, the combustion cylinder ratio is similarly changed by changing the cylinder deactivation pattern so that the cylinder deactivation interval changes by one cylinder. Is changed. In this way, the combustion cylinder ratio is changed in the intermittent deactivation operation range by changing the cylinder deactivation pattern so that the cylinder deactivation interval changes by one cylinder at a time.

By the way, when the operating range of the engine 10 shifts from the intermittent deactivation operating range to the all-cylinder combustion operating range, the cylinder deactivation interval is set until the identification number corresponding to the 88% combustion cylinder ratio becomes the cylinder deactivation pattern of 7. The cylinder deactivation pattern is sequentially changed so as to change for each cylinder. Then, after executing the cylinder deactivation pattern with the identification number 7, the shift to the cylinder deactivation pattern with the identification number 8 corresponding to the 100% combustion cylinder ratio, that is, to the all-cylinder combustion operation. In this case, even if the operating range of the engine 10 is in the all-cylinder combustion operating range, the intermittent deactivation operation is continued until the cylinder deactivation pattern with the identification number 7 is switched to the cylinder deactivation pattern with the identification number 8. become.

Further, in the above embodiment, when the combustion cylinder ratio is the same value as the target combustion cylinder ratio, the cylinder deactivation pattern corresponding to the target combustion cylinder ratio is repeated. That is, in this case, the cylinder deactivation interval is kept constant.

In the present embodiment, the variable control of the combustion cylinder ratio is performed in the above embodiment. Such variable control of the combustion cylinder ratio is realized by changing the frequency of cylinder deactivation during the intermittent deactivation operation of the engine 10. In the engine 10 during intermittent deactivation, the engine speed drops once in response to cylinder deactivation and then increases in response to combustion in the cylinder. The amount of increase in the engine speed at this time increases as the number of combustion cylinders until the next cylinder deactivation increases, that is, as the cylinder deactivation interval becomes longer. Therefore, if a section having a long cylinder deactivation interval and a section having a short cylinder deactivation interval are mixed, the engine rotation fluctuation becomes large.

On the other hand, in the present embodiment, the pause interval of the cylinders is kept constant while the combustion cylinder ratio is constant. Also, when changing the combustion cylinder ratio, the cylinder pause interval changes only by one cylinder. Therefore, it is possible to suppress fluctuations in engine rotation due to changes in cylinder deactivation intervals.

It should be noted that fluctuations in engine rotation due to changes in cylinder deactivation intervals can be suppressed by individual torque management for each cylinder. That is, by adjusting the cylinder intake air amount and ignition timing of each cylinder, the torque generation amount of each cylinder that burns in the section where the cylinder deactivation interval is short is made larger than that in the section where the interval is long, and until the next cylinder deactivation. If the amount of increase in the engine speed is made uniform, it is possible to suppress the fluctuation of the engine speed due to the change of the cylinder deactivation interval.

Also in this embodiment, when the combustion cylinder ratio is changed, the cylinder deactivation interval is also changed, so that individual torque management for each cylinder may be required in order to sufficiently suppress the rotational fluctuation of the engine 10. Even in such a case, in the present embodiment, since the cylinder pause interval is changed stepwise by one cylinder to change the combustion cylinder ratio, the engine 10 can be adjusted only by making a small adjustment of the torque generation amount for each cylinder. Rotational fluctuation is suppressed.

The above embodiment can also be modified and implemented as follows.
-The division between the all-cylinder combustion operation area and the intermittent operation pause operation area in the operation range of the engine 10 and the division of the target combustion cylinder ratio in the intermittent operation suspension operation area may be different from those in FIG.

-In the above embodiment, seven patterns with cylinder deactivation intervals of 1 to 7 are set as cylinder deactivation patterns used when changing the combustion cylinder ratio by variable control of the combustion cylinder ratio. As long as the number of cylinders at the cylinder deactivation interval of each pattern is continuous, the number and types of such cylinder deactivation patterns may be appropriately changed.

(Second Embodiment)
Next, the variable control method of the combustion cylinder ratio and the second embodiment of the variable control device will be described in detail with reference to FIGS. 5 and 6.

As shown in FIG. 5, the variable control device of the present embodiment is applied to a V-type 6-cylinder engine 10'in which three cylinders are provided in two banks of the first bank B1 and the second bank B2, respectively. .. In the following description, the three cylinders provided in the first bank B1 are described as cylinders # 1, cylinders # 3, and cylinders # 5, respectively, and the three cylinders provided in the second bank B2 are referred to as cylinders # 2, respectively. Described as cylinder # 4 and cylinder # 6. At this time, the firing order of cylinders # 1 to # 6 in the engine 10'is the order of cylinder # 1, cylinder # 2, cylinder # 3, cylinder # 4, cylinder # 5, and cylinder # 6.

The electronic control unit 11'that controls the engine 10' includes a combustion cylinder ratio variable control unit 12' as a variable control device for the combustion cylinder ratio. The combustion cylinder ratio variable control unit 12'has a target combustion cylinder ratio calculation unit 13'that calculates a target combustion cylinder ratio according to the operating state of the engine 10', and a cylinder deactivation pattern of the engine 10'based on the target combustion cylinder ratio. It is provided with a cylinder deactivation pattern determination unit 14'that determines. Then, the combustion cylinder ratio variable control unit 12'controls the engine 10'so that the cylinder deactivation is performed according to the determined cylinder deactivation pattern.

FIG. 6 shows the relationship between the value of the target combustion cylinder ratio calculated by the target combustion cylinder ratio calculation unit 13', the required torque, and the engine speed. The target combustion cylinder ratio calculation unit 13'reads the engine speed and the required torque for each specified control cycle, and calculates the target combustion cylinder ratio from the engine speed and the required torque. As shown in the figure, in the present embodiment, the target combustion cylinder ratio is calculated so that the value is any one of 33%, 50%, 67%, 71%, 75%, and 100%. Specifically, the target combustion cylinder ratio is fixed at 100% in the operating range of the engine 10'where the required torque exceeds the default value γ and in the operating range of the engine 10' where the engine speed is below the default value ε. On the other hand, in the operating range of the engine 10'where the required torque is γ or less and the engine speed is ε or more, the target combustion cylinder ratio is in the range of 33% to 75% depending on the required torque. Be changed.

On the other hand, also in this embodiment, the cylinder deactivation pattern determination unit 14'determines the cylinder deactivation pattern performed by the engine 10'based on the target combustion cylinder ratio. In the present embodiment, the cylinder deactivation pattern determination unit 14'selects any of the 12 cylinder deactivation patterns shown in Table 2 as the cylinder deactivation pattern performed by the engine 10'.

As shown in the table, the 12 cylinder deactivation patterns used in this embodiment are 0%, 33%, 50%, 60%, 67%, 71%, 75%, 78%, 80% and 82%. , 83%, and 100% combustion cylinder ratio, respectively. Of these, in the 10 cylinder deactivation patterns, excluding the cylinder deactivation patterns corresponding to the ratio of both combustion cylinders of 0% indicating all cylinder deactivation and 100% indicating all cylinder combustion, N (1) in the order of the cylinders reaching the combustion stroke. Cylinder deactivation is repeated in a pattern in which combustion is paused for two cylinders in succession after burning three cylinders in succession. That is, all the cylinder deactivation patterns used during the intermittent deactivation operation have a ratio that can be realized by repeating the cylinder deactivation of the above pattern, that is, by repeating the cylinder deactivation at regular intervals.

In the present embodiment, each of the above 12 cylinder deactivation patterns is assigned an identification number (ID) whose value is the number of cylinders (N) that continuously burn in each pattern. Further, in the present embodiment, when the combustion cylinder ratio is 0% (all cylinders are deactivated), a pattern consisting of two consecutive cylinder deactivations is set as a cylinder deactivation pattern for convenience, and the identification number is set to "0". .. Further, in the present embodiment, when the ratio of combustion cylinders in which only combustion is repeated is 100% (all cylinder combustion), a pattern consisting of continuous combustion of two cylinders is set as a cylinder deactivation pattern for convenience, and the identification number is ". 11 ".

Then, the cylinder deactivation pattern determination unit 14'actually performs any of the cylinder deactivation patterns of the identification numbers 0 to 11 in the engine 10'based on the target combustion cylinder ratio calculated by the target combustion cylinder ratio calculation unit 13. Determined as a cylinder deactivation pattern. The cylinder deactivation pattern determination unit 14'of this embodiment also determines the cylinder deactivation pattern according to the cylinder deactivation pattern determination routine of FIG. That is, also in the present embodiment, the combustion cylinder ratio is changed by sequentially changing the cylinder deactivation pattern so that the identification number changes by one. Further, also in the present embodiment, the value of the identification number of the cylinder deactivation pattern used during the intermittent deactivation operation corresponds to the cylinder deactivation interval when the corresponding cylinder deactivation pattern is repeated. Therefore, also in the present embodiment, when the target combustion cylinder ratio and the current combustion cylinder ratio match, the cylinder pause pattern determination unit 14'sets the interval at which the target combustion cylinder ratio can be realized as the next pause interval. When the target combustion cylinder ratio and the current combustion cylinder ratio do not match, the interval for achieving the target combustion cylinder ratio is closer to one cylinder than the interval for achieving the current combustion cylinder ratio as the next pause interval. ..

Even in the present embodiment configured as described above, the pause interval between cylinders is kept constant while the combustion cylinder ratio is constant. Further, when the combustion cylinder ratio is changed, the pause interval of the cylinders changes only by one cylinder. Therefore, the variable control method and the variable control device of the present embodiment can also suppress the rotation fluctuation of the engine due to the change of the cylinder deactivation interval when the variable control of the combustion cylinder ratio is performed.

Here, in the engine of the V-type cylinder array, the intermittent combustion operation by repeating the cylinder deactivation of the pattern in which the combustion of one cylinder is deactivated after continuously combusting N cylinders as in the first embodiment is performed. Think about what to do. In such a case, if intermittent combustion is performed in a pattern in which the value of N is an odd number, the cylinders that stop combustion are concentrated in one of the two banks. As a result, the exhaust properties of both banks may be biased, making emission control difficult. On the other hand, in the present embodiment, in the engine 10'in which the ignition order is set so as to alternately burn between the first bank B1 and the second bank B2, the combustion suspension during the intermittent combustion operation is 2 I try to do it continuously for each cylinder. Therefore, combustion is suspended by one cylinder in each of the first bank B1 and the second bank B2, and the bias of the exhaust properties between the banks can be suppressed.

If a cylinder deactivation pattern that suspends combustion for two cylinders in a row is adopted, the fluctuation of the engine torque during intermittent combustion operation becomes larger than that when a cylinder deactivation pattern that suspends combustion with only one cylinder is adopted. .. Here, the period during which the engine torque is not generated when the combustion is stopped for two consecutive cylinders is 360 ° CA for the 4-cylinder engine, but 240 ° CA for the 6-cylinder engine. As described above, as the number of cylinders of the engine increases, the period during which the engine torque is not generated when the combustion is stopped for two consecutive cylinders becomes shorter. Therefore, in an engine having a large number of cylinders, even if a cylinder deactivation pattern in which combustion is deactivated for two cylinders in a row is adopted, it is easy to keep the fluctuation of the engine torque within an acceptable range.

10, 10'... engine, 11, 11' ... electronic control unit, 12, 12' ... combustion cylinder ratio variable control unit (variable control device for combustion cylinder ratio), 13, 13' ... target combustion cylinder ratio calculation unit, 14 , 14'... Cylinder suspension pattern determination unit.

Claims (1)

In the combustion cylinder ratio variable control device that performs variable control of the combustion cylinder ratio of the engine during intermittent deactivation operation in which cylinder deactivation is performed intermittently
A target combustion cylinder ratio calculation unit that calculates the combustion cylinder ratio that can be realized by repeating cylinder deactivation at regular intervals as the target combustion cylinder ratio,
When the interval between cylinder suspensions from the cylinder suspension to the next cylinder suspension at the interval that realizes the current combustion cylinder ratio is set as the next suspension interval, the target combustion cylinder ratio and the current combustion cylinder ratio are When they match, the interval at which the target combustion cylinder ratio can be realized is set as the next pause interval, and when the target combustion cylinder ratio and the current combustion cylinder ratio do not match, the current combustion cylinder ratio is realized. A cylinder pause pattern determination unit that sets an interval closer to one cylinder as the interval that can realize the target combustion cylinder ratio than the interval as the next pause interval, and
A variable control device for the combustion cylinder ratio.