JP6730952B2 - ENGINE OPERATION CONTROL DEVICE AND ENGINE OPERATION CONTROL METHOD - Google Patents

Description

The present invention provides an operation control device for an engine, which supplies a first fuel and a second fuel having different ignitability to each other in a combustion chamber, and premixes compression self-ignition combustion of an air-fuel mixture including the first fuel and the second fuel, and , An engine operation control method.

Conventionally, in addition to a fuel injection valve for injecting a main fuel (first fuel) into a combustion chamber, a fuel injection valve for injecting an ignition fuel (second fuel) having a higher self-ignitability than the main fuel is provided, and a compression stroke is provided. There is known a technique of flame-propagating combustion of a premixed gas (main fuel + air) in a combustion chamber, triggered by self-ignition combustion of ignition fuel injected in (1). While this type of combustion method can realize stable combustion with high ignition energy, there is an increasing demand for reducing NOx and PM contained in exhaust gas.

JP, 2009-91995, A

In order to reduce NOx and PM, in recent years, premixed compression ignition combustion (for example, PCCI, RCCI) in which fuel and air are premixed and compression self-ignition is attracted attention. However, in this premixed compression self-ignition combustion, it becomes difficult to secure the ignition delay period as the load increases, so that in medium to high load operation, abnormal combustion such as excessive combustion speed tends to occur. Therefore, there is a problem that the operation applicable range is relatively limited to the low load region.

In order to solve this problem, it is possible to provide a sensor for detecting the combustion state in the cylinder and control the amount of injection fuel and the injection timing so that proper combustion is achieved based on the detection signal. If the fuel to be used is changed, it may be out of the control range. Further, in an engine having a plurality of cylinders, all the cylinders are normally operated under substantially the same load. Therefore, if abnormal combustion occurs due to high load operation, it is necessary to reduce the load on all the cylinders to avoid it. there were.

The present invention has been made in view of the above, and an engine operation control device and an engine operation control method that grasp an allowable limit load at which abnormal combustion may occur and can perform stable premixed autoignition combustion operation. The purpose is to provide.

In order to solve the above-mentioned problems and achieve the object, the present invention has a plurality of cylinders, supplies a first fuel into the combustion chamber of the cylinders, and has a higher ignitability than the first fuel. An engine operation control device for performing a premixed compression self-ignition combustion operation in which two fuels are directly injected into a combustion chamber, and a mixture including a first fuel and a second fuel is compressed to perform self-ignition combustion. A control unit capable of executing an operation mode in which a part of the cylinders is operated at a load higher than the engine required load and the remaining cylinders of the plurality of cylinders are operated at a load lower than the engine required load, and A determining unit that determines whether abnormal combustion occurs in a cylinder operating at a high load, and a setting unit that, when it is determined that abnormal combustion occurs, sets the load value at which abnormal combustion occurs as an allowable limit load. The control unit is characterized by performing the premixed compression autoignition combustion operation on all cylinders until the required engine load reaches the allowable limit load.

According to this configuration, the allowable limit load is set from the operating condition of some cylinders, and for all the cylinders, the premixed compression autoignition combustion operation is executed until the engine required load reaches the allowable limit load, It is possible to prevent abnormal combustion from occurring in all cylinders, and it is possible to perform stable combustion in a region up to the allowable limit load.

In this configuration, the control unit operates by increasing the load of some cylinders by increasing at least one of the supply amount of the first fuel and the injection amount of the second fuel in some cylinders rather than the remaining cylinders. It may be configured to. According to this configuration, it is possible to easily perform an operation with a different load between some of the cylinders and the remaining cylinders.

Further, when it is determined that some of the cylinders have abnormal combustion, the control unit adjusts the operating conditions of the premixed compression self-ignition combustion operation for some of the cylinders to suppress the occurrence of abnormal combustion while exceeding the allowable limit load. New operating conditions may be tried. According to this configuration, by trying new operating conditions, it is possible to increase the allowable limit load, and it is possible to realize stable combustion on the higher load side.

When the engine required load increases beyond the allowable limit load, the control unit supplies the first fuel into the combustion chambers of all the cylinders and enters the combustion chambers in the process of compressing the air-fuel mixture containing the first fuel. Pilot flame propagation combustion may be executed in which the second fuel is directly injected as pilot fuel and self-ignited for combustion. According to this configuration, by changing the premixed compression self-ignition combustion operation to the pilot flame propagation combustion operation, stable combustion can be realized even when the engine required load increases beyond the allowable limit load.

In addition, the control unit may sequentially select and determine a part of the cylinders from the plurality of cylinders. With this configuration, it is possible to prevent the load from being improperly applied to a specific cylinder, and it is possible to maintain the engine performance for a long time.

Further, the present invention has a plurality of cylinders, supplies the first fuel into the combustion chamber of the cylinders, and directly injects the second fuel having a higher ignitability than the first fuel into the combustion chamber. A method for controlling an engine for executing a premixed compression auto-ignition combustion operation in which a mixture including fuel and a second fuel is compressed and self-ignited and burned, wherein a part of a plurality of cylinders is loaded more than an engine required load. A process of operating a high load and operating the remaining cylinders of a plurality of cylinders at a load lower than the engine required load, and whether abnormal combustion occurs in the cylinders operated at a load higher than the engine required load. If it is determined that abnormal combustion has occurred, a step of setting the load value at which the abnormal combustion has occurred as an allowable limit load, and until the engine required load reaches the allowable limit load for all cylinders. And performing a premixed compression autoignition combustion operation.

According to the present invention, the allowable limit load is set from the operating condition of some of the cylinders, and for all the cylinders, to perform the premixed compression autoignition combustion operation until the engine required load reaches the allowable limit load, It is possible to prevent abnormal combustion from occurring in all cylinders, and it is possible to perform stable combustion in a region up to the allowable limit load.

FIG. 1 is a diagram showing a functional configuration of an engine operation control device according to the present embodiment. FIG. 2 is a graph showing changes in the load amount of each cylinder of the engine. FIG. 3 is a flowchart showing the control procedure of the engine. FIG. 4 is a flowchart showing an engine control procedure according to another embodiment.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings, but the present invention is not limited thereto. The components of the embodiments described below can be combined as appropriate. In addition, some components may not be used.

FIG. 1 is a diagram showing a functional configuration of an engine operation control device according to the present embodiment. As shown in FIG. 1, an engine 10 according to the present embodiment has a cylinder head 12 fastened on a cylinder block 11, and a plurality of (for example, four) cylinders 13 (13A to 13) formed in the cylinder block 11. 13D) is a multi-cylinder engine. The cylinders 13A to 13D are simply referred to as the cylinder 13 unless it is necessary to distinguish them. The engine 10 includes a piston 14 housed in each cylinder 13 so as to be reciprocally movable. While the piston 14 reciprocates two times, a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke are performed. This is a so-called 4-cycle engine.

A combustion chamber 15 is formed in the cylinder 13. The combustion chamber 15 includes an inner wall surface 13A1 of the cylinder 13, a lower surface 12A of the cylinder head 12, and a top surface 14A of the piston 14. In the present embodiment, the engine 10 is configured as a dual fuel engine in which two types of first fuel F1 and second fuel F2 having different ignitability are supplied into the combustion chamber 15, and the first fuel F1 is a natural fuel. Gas is used, and light oil is used as the second fuel F2 having a higher ignitability than the first fuel F1. In addition to this, gasoline or LPG (liquefied petroleum gas) can be used as the first fuel F1. Further, it is also possible to adopt a configuration in which the ignitability is made different by adding different fuel additives to the same fuel (for example, light oil).

An intake port 16 and an exhaust port 17 are formed on the lower surface 12A of the cylinder head 12, which is the upper portion of the combustion chamber 15. An intake valve 18 and an exhaust valve 19 are arranged in the intake port 16 and the exhaust port 17, respectively, and the intake valve 18 and the exhaust valve 19 are opened and closed by a variable valve mechanism (not shown).

Further, the intake port 16 is provided with a first fuel injection valve 20 that injects the above-described first fuel F1. The first fuel F1 injected from the first fuel injection valve 20 is supplied into the combustion chamber 15 together with air through the intake port 16 in the intake stroke, and the air-fuel mixture of the first fuel F1 is generated in the combustion chamber 15. Is generated. In the center of the upper surface of the combustion chamber 15, a second fuel injection valve 21 for directly injecting the second fuel F2 into the combustion chamber 15, and a pressure sensor 22 for detecting a pressure change as a combustion state in the combustion chamber 15. And are provided.

The first fuel injection valve 20, the second fuel injection valve 21, and the pressure sensor 22 are connected to the operation control device 30. The operation control device 30 includes a control unit 31, a determination unit 32, and a setting unit 33. The control unit 31 controls the overall operation of the engine 10 by controlling the fuel injection amount and injection timing of the first fuel injection valve 20 and the second fuel injection valve 21. The total required load to the engine 10 is transmitted to the control unit 31 by the opening degree of the accelerator 35 and the like. The control unit 31 determines the load shared by each cylinder 13 in accordance with the transmitted total required load, and controls the operation of each cylinder 13 based on the magnitude of this load.

In the present embodiment, the control unit 31 is configured to be operable by changing the load of each cylinder 13. Specifically, the control unit 31 determines the injection amount of the second fuel F2 injected from the second fuel injection valve 21 of one cylinder 13A (a part of the cylinders) from the injection amounts of the remaining cylinders 13B to 13D. Also, the load exerted by one cylinder 13A is increased more than the load exerted by the remaining cylinders 13B to 13D. Of course, the injection amount (supply amount) of the first fuel F1 injected from the first fuel injection valve 20 may be increased, or both the first fuel F1 and the second fuel F2 may be increased. Further, the cylinder 13 whose load is to be increased is not a specific cylinder, and the control unit 31 sequentially selects and changes the rotation every time a predetermined operation time elapses. As a result, it is possible to prevent the operation of each cylinder 13 from being biased, and it is possible to maintain the engine performance for a long time.

Further, the control unit 31 appropriately adjusts the fuel injection timing (timing) of the second fuel injection valve 21 to compress the air-fuel mixture containing the first fuel F1 and the second fuel F2 and self-ignite the air-fuel mixture. A premixed compression self-ignition combustion operation for combustion and a micro-pilot flame propagation combustion operation (pilot flame propagation combustion operation) for self-ignition combustion of a mixture containing the first fuel F1 using the second fuel F2 as pilot fuel are selected. And is configured to be executable.

In the premixed compression self-ignition combustion operation, the second fuel F2 is injected into the combustion chamber 15 in the middle of the compression stroke to generate a mixture containing the first fuel F1 and the second fuel F2 in the combustion chamber 15. This is a combustion method in which the generated air-fuel mixture is compressed and the entire air-fuel mixture is ignited and combusted from the second fuel F2 having high ignitability.

On the other hand, in the micro-pilot flame propagation combustion operation, the second fuel F2 functions as a pilot fuel by injecting the second fuel F2 into the combustion chamber 15 at the latter stage of the compression stroke of the air-fuel mixture including the first fuel F1. However, it is a combustion method in which the air-fuel mixture containing the first fuel F1 is self-ignited and burned.

The premixed compression self-ignition combustion operation has attracted particular attention in recent years because it has an advantage that NOx and PM contained in exhaust gas can be reduced as compared with the micro-pilot flame propagation combustion operation. However, in the premixed compression self-ignition combustion operation, it becomes difficult to secure the ignition delay period as the load increases, so that in medium to high load operation, abnormal combustion such as excessive combustion speed tends to occur. It is in. For this reason, in the control of the engine 10 in the present configuration, the micro-pilot flame propagation, which is a combustion method that is more stable than the premixed compression self-ignition combustion operation, according to the increase in load, is based on the premixed compression self-ignition combustion operation. The stable combustion control of the engine 10 is realized by switching to the combustion operation.

The determination unit 32 determines whether or not abnormal combustion has occurred in the cylinder 13A having the increased load. Specifically, the determination unit 32 monitors the pressure change rate in the cylinder 13 from the detection value of the pressure sensor 22 and determines that abnormal combustion has occurred when the pressure change rate is outside a predetermined allowable range. The setting unit 33 acquires the load value of the cylinder 13A when the determination unit 32 determines that abnormal combustion has occurred, and sets this load value as the allowable limit load.

Next, the operation of the operation control device will be described. FIG. 2 is a graph showing changes in the load amount of each cylinder of the engine. FIG. 3 is a flowchart showing the operation procedure.

In FIG. 2, a broken line 50 that rises to the right with the lapse of time represents the required engine load. In this case, the engine required load corresponds to the total required load divided by the number of cylinders (total required load/number of cylinders). Further, at the time of low load operation immediately after the start of operation, the control unit 31 executes the premixed compression ignition combustion operation for all the cylinders 13.

The control unit 31 sets one cylinder 13A as a high-load cylinder that operates at a load higher than the engine required load 50 (step S1). In this case, the control unit 31 sets the remaining cylinders 13B to 13D as the cylinders that are operated with a load lower than the engine required load 50. Next, the control unit 31 acquires the engine required load 50 (step S2), and based on the acquired engine required load 50, the load 51 of one cylinder 13A, which is a high load cylinder, and the remaining cylinders 13B to 13D. Each load 52 is set individually (step S3). The load 51 of the one cylinder 13A and the loads 52 of the remaining cylinders 13B to 13D are set such that the average load 53 thereof is substantially equal to the engine required load 50. As a result, the load 51 of the specific (high-load cylinder) cylinder 13A can be increased in advance while satisfying the engine required load 50.

Next, the control unit 31 determines through the determination unit 32 whether or not abnormal combustion has occurred in the one cylinder 13A that is a high load cylinder (step S4). In this determination, if abnormal combustion has not occurred (step S4; No), the process is returned to step S2, and steps S2 to S4 are executed based on the engine load demand 50 at that time. On the other hand, when abnormal combustion has occurred (step S4; Yes), the control unit 31 causes the setting unit 33 to set the load value at which abnormal combustion has occurred as the allowable limit load Q (step S5).

In the present embodiment, by operating the one cylinder 13A set as the high load cylinder at a load 51 higher than the engine required load 50, the allowable limit load Q at which abnormal combustion occurs in the premixed compression auto ignition combustion operation is preceded. And you can figure it out. If the load is lower than the allowable limit load Q, abnormal combustion does not occur. Therefore, until the engine required load 50 reaches the allowable limit load Q, the loads 52 of the remaining cylinders 13B to 13D should be stably increased. Therefore, the premixed compression autoignition combustion operation for all the cylinders 13A to 13D can be stably performed. In this case, the one cylinder 13A set as the high-load cylinder operates with the load 51 corresponding to the allowable limit load Q even if the engine required load 50 increases.

Next, the control unit 31 determines whether the required engine load 50 exceeds the allowable limit load Q (step S6). In this determination, if the engine required load 50 does not exceed the allowable limit load Q (step S6; No), the premixed compression self-ignition combustion operation is continuously executed as it is. On the other hand, when the engine required load 50 exceeds the allowable limit load Q (step S6; Yes), abnormal combustion may occur in all the cylinders 13, and therefore all the cylinders 13 are operated by the micro pilot flame propagation combustion operation. To (step S7). This micro-pilot flame propagation combustion operation can realize more stable combustion in the high load region than the premixed compression self-ignition combustion operation. Therefore, the combustion of the engine 10 is stabilized by changing to the micro-pilot flame propagation combustion operation. be able to. Further, since the change from the premixed compression self-ignition combustion operation to the micro pilot flame propagation combustion operation can be realized only by changing the fuel injection timing and the injection amount of the second fuel injection valve 21, the control of the existing device is changed. All you have to do is

Next, another embodiment will be described. In this another embodiment, in order to not only first grasp the allowable limit load Q in which abnormal combustion occurs in the premixed compression self-ignition combustion operation, but also to increase the allowable limit load Q, a high load cylinder is set. This is different from the above-described embodiment in that the operating condition of the other cylinder 13A is tried. Since the configurations of the engine 10 and the operation control device 30 are the same, the same reference numerals are given and the description thereof is omitted. FIG. 4 is a flowchart showing an engine control procedure according to another embodiment.

As shown in FIG. 4, the control unit 31 sets one cylinder 13A as a high-load cylinder that operates at a load higher than the engine required load 50 (step S11). In this case, the control unit 31 sets the remaining cylinders 13B to 13D as the cylinders that are operated with a load lower than the engine required load 50. Next, the control unit 31 acquires the engine required load 50 (step S12), and based on the acquired engine required load 50, the load 51 of the one cylinder 13A, which is a high load cylinder, and the remaining cylinders 13B to 13D. Each load 52 is set (step S13). The load 51 of the one cylinder 13A and the loads 52 of the remaining cylinders 13B to 13D are set such that the average load 53 thereof is substantially equal to the engine required load 50. As a result, the load 51 of the specific (high-load cylinder) cylinder 13A can be increased in advance while satisfying the engine required load 50.

Next, the control unit 31 determines through the determination unit 32 whether or not abnormal combustion has occurred in the one cylinder 13A that is a high load cylinder (step S14). If abnormal combustion does not occur in this determination (step S14; No), the process returns to step S12, and steps S12 to S14 are executed based on the engine load demand 50 at that time. On the other hand, when abnormal combustion has occurred (step S14; Yes), the control unit 31 causes the setting unit 33 to set the load value at which abnormal combustion has occurred as the allowable limit load Q (step S15).

Next, the control unit 31 adjusts the operating condition of the one cylinder 13A which is a high load cylinder (step S16). Specifically, the control unit 31 adjusts the fuel injection pressure and the injection timing of the second fuel injection valve 21 in the one cylinder 13A, and controls the first fuel F1 and the second fuel F1 in the combustion chamber 15 based on the control program. The ratio (weight ratio or volume ratio) of the air-fuel mixture containing the fuel F2 is adjusted. This kind of operation condition adjustment is performed under the condition that the average load 53 of all the cylinders 13A to 13D satisfies the engine required load 50.

Next, the control unit 31 determines whether or not the one cylinder 13A can be operated with the load 51 higher than before under the adjusted operating conditions (step S17). Specifically, the control unit 31 operates by operating the load 51 of the one cylinder 13A higher than the previous load under the adjusted operating conditions, and whether abnormal combustion occurs in the one cylinder 13A in this state. To determine. In this determination, if it is not possible to operate with the load 51 higher than before (step S17; No), the process proceeds to step S19. In this case, the control unit 31 proceeds to step S19 even if the operation condition adjustment is tried a predetermined number of times (predetermined time), if the operation cannot be performed with the load 51 higher than before.

On the other hand, in this determination, if it is possible to operate with the load 51 higher than before (step S17; Yes), the allowable limit load Q is raised and updated (step S18). In this case, when the load 51 of the cylinder 13A reaches the load corresponding to the previous allowable limit load Q, the control unit 31 controls under the newly adjusted operating condition.

In the present embodiment, by trying new operating conditions, it is possible to increase the allowable limit load Q at which abnormal combustion occurs in the premixed compression self-ignition combustion operation. Therefore, stable combustion on a higher load side can be realized for all the cylinders 13A to 13D.

Next, the control unit 31 determines whether or not the engine request load 50 exceeds the allowable limit load Q (step S19). When the allowable limit load Q is updated in step S18, the updated allowable limit loads Q are compared. In this determination, if the engine required load 50 does not exceed the allowable limit load Q (step S19; No), the premixed compression autoignition combustion operation is continuously executed as it is. On the other hand, when the engine required load 50 exceeds the allowable limit load Q (step S19; Yes), abnormal combustion may occur in all the cylinders 13, and therefore all the cylinders 13 are operated by the micro pilot flame propagation combustion operation. To (step S20). This micro-pilot flame propagation combustion operation can realize more stable combustion than the premixed compression self-ignition combustion operation in the high load region. Therefore, the combustion of the engine 10 is stabilized by changing to the micro pilot flame propagation combustion operation. be able to. Furthermore, since the change from the premixed compression self-ignition combustion operation to the micro pilot flame propagation combustion operation can be realized only by changing the fuel injection timing and the injection amount of the second fuel injection valve 21, the control of the existing device is changed. All you have to do is

As described above, according to the present embodiment, the plurality of cylinders 13 are provided, the first fuel F1 is supplied into the combustion chamber 15 of each cylinder 13, and the ignitability is higher than that of the first fuel F1. Of the engine 10 that executes the premixed compression self-ignition combustion operation in which the second fuel F2 having a high fuel injection rate is directly injected into the combustion chamber 15 and the air-fuel mixture including the first fuel F1 and the second fuel F2 is compressed to perform self-ignition combustion. The operation control device 30 can execute an operation mode in which one cylinder 13A is operated with a load 51 higher than the engine required load 50 and the remaining cylinders 13B to 13D are operated with a load 52 lower than the engine required load 50. Control unit 31, a determination unit 32 that determines whether or not abnormal combustion occurs in one cylinder 13A operating at a load 51 higher than the engine required load 50, and if abnormal combustion is determined, the abnormal combustion occurs. The control unit 31 includes a setting unit 33 that sets the generated load value as an allowable limit load Q, and the control unit 31 controls the premixed compression self-ignition for all cylinders 13 until the required engine load 50 reaches the allowable limit load Q. Since the combustion operation is performed, it is possible to avoid abnormal combustion in all the cylinders 13A to 13D, and it is possible to perform stable combustion in a region up to the allowable limit load Q.

Further, according to the present embodiment, the control unit 31 increases the injection amount of at least one of the first fuel F1 and the second fuel F2 in the one cylinder 13A more than the remaining cylinders 13B to 13D, thereby increasing the injection amount. Since the load 51 of the cylinder 13A is increased for the operation, it is possible to easily perform the operation in which the load is different between the one cylinder 13A and the remaining cylinders 13B to 13D.

Further, according to the present embodiment, when it is determined that the one cylinder 13A is in the abnormal combustion state, the control unit 31 adjusts the operating condition of the premixed compression autoignition combustion operation for the one cylinder 13A, and the allowable limit load Q Since a new operating condition that suppresses the occurrence of abnormal combustion is tried while exceeding the above, the allowable limit load Q can be increased, and stable combustion on a higher load side can be realized.

Further, according to the present embodiment, when the engine required load 50 increases beyond the allowable limit load Q, the control unit 31 supplies the first fuel F1 into the combustion chambers 15 of all the cylinders 13, and In the process of compressing the air-fuel mixture containing the first fuel F1, the second fuel F2 is directly injected into the combustion chamber 15 as pilot fuel to perform self-ignition combustion. Stable combustion can be realized even when the amount exceeds the limit.

Further, according to the present embodiment, the control unit 31 sequentially selects and determines one high-load cylinder from the plurality of cylinders 13, so that the load is biased to a specific cylinder. This can be prevented and engine performance can be maintained for a long time.

Although one embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. The present embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. The present embodiment and its modifications are included in the invention described in the claims and the scope equivalent thereto, as well as being included in the scope and the gist of the invention.

For example, in the present embodiment, since the one cylinder 13A is set as the high load cylinder, there is an advantage that the load 51 of the one cylinder 13A is quickly increased to a load at which abnormal combustion can occur. It is also possible to set a plurality of cylinders. According to this configuration, the plurality of cylinders can independently adjust the operating conditions of the premixed compression self-ignition combustion operation and try new operating conditions that suppress the occurrence of abnormal combustion while exceeding the allowable limit load Q. Therefore, new operating conditions can be found early.

10 engine 13 cylinder 13A one cylinder (some cylinders)
13B, 13C, 13D Remaining cylinders 15 Combustion chamber 16 Intake port 17 Exhaust port 20 First fuel injection valve 21 Second fuel injection valve 22 Pressure sensor 30 Operation control device 31 Control unit 32 Discrimination unit 33 Setting unit 50 Engine required load 51 , 52 load F1 first fuel F2 second fuel Q allowable limit load

Claims (6)

A plurality of cylinders are provided, the first fuel is supplied into the combustion chamber of the cylinders, and the second fuel having a higher ignitability than the first fuel is directly injected into the combustion chamber. An engine operation control device for executing a premixed compression auto-ignition combustion operation for compressing an air-fuel mixture containing a second fuel and performing self-ignition combustion, comprising:
A control unit capable of executing an operation mode in which a part of the plurality of cylinders is operated at a load higher than an engine required load and the remaining cylinders of the plurality of cylinders are operated at a lower load than the engine required load. When,
A determination unit that determines whether abnormal combustion occurs in the cylinder operating at a load higher than the engine required load,
If it is determined to be abnormal combustion, a setting unit that sets the load value at which the abnormal combustion has occurred as an allowable limit load,
The control unit executes the premixed compression self-ignition combustion operation for all the cylinders until the engine required load reaches the allowable limit load.
An engine operation control device characterized by the above. The control unit increases the load of some of the cylinders by increasing at least one of the supply amount of the first fuel and the injection amount of the second fuel in some of the cylinders rather than the remaining cylinders. The engine operation control device according to claim 1, wherein the engine operation control device is operated as follows. The control unit, when a part of the cylinders is determined to be the abnormal combustion, adjusts the operating condition of the premixed compression autoignition combustion operation for a part of the cylinders,
The engine operation control device according to claim 1, wherein a new operation condition for suppressing the occurrence of the abnormal combustion is tried while exceeding the allowable limit load. When the engine required load increases beyond the allowable limit load,
The control unit supplies the first fuel into the combustion chambers of all the cylinders and directly injects the second fuel into the combustion chambers as pilot fuel in the process of compressing the air-fuel mixture containing the first fuel. The engine operation control device according to any one of claims 1 to 3, characterized in that pilot flame propagating combustion for performing self-ignition combustion is executed. The engine operation control device according to claim 1, wherein the control unit sequentially selects and determines a part of the cylinders from a plurality of the cylinders. A plurality of cylinders are provided, the first fuel is supplied into the combustion chamber of the cylinders, and the second fuel having a higher ignitability than the first fuel is directly injected into the combustion chamber. A method for controlling the operation of an engine for executing a premixed compression auto-ignition combustion operation in which a mixture containing a second fuel is compressed to perform self-ignition combustion.
Executing a driving mode in which a part of the plurality of cylinders is operated at a load higher than an engine required load, and the remaining cylinders of the plurality of cylinders are operated at a lower load than the engine required load;
A step of determining whether or not abnormal combustion occurs in the cylinder operating at a load higher than the engine required load,
If it is determined to be abnormal combustion, a step of setting the load value at which the abnormal combustion occurs as an allowable limit load,
Performing the premixed compression autoignition combustion operation on all the cylinders until the engine required load reaches the allowable limit load;
An engine operation control method comprising:

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