JP2018168726A - Operation control device for engine and operation control method for engine - Google Patents

Abstract

To provide an operation control device for an engine and an operation control method for the engine capable of identifying a tolerance limit load that may causes abnormal combustion and executing stable premixing self-ignition combustion operation.SOLUTION: An operation control device for an engine that executes premixing compression self-ignition combustion operation for compressing an air-fuel mixture including first fuel and second fuel for self-ignition combustion includes: a control section capable of executing an operation mode of operating one cylinder at a load 51 higher than an engine demand load 50 and operating remaining cylinders at a load 52 lower than the engine demand load 50; a determination section for determining whether abnormal combustion occurs in one cylinder operated at the load 51 higher than the engine demand load 50; and a setting section for setting a load value that causes the abnormal combustion as a tolerance limit load Q when the abnormal combustion is determined. The control section executes the premixing compression self-ignition combustion operation to all of the cylinders until the engine demand load 50 reaches the tolerance limit load Q.SELECTED DRAWING: Figure 2

Description

  The present invention provides an operation control device for an engine that supplies first and second fuels having different ignitability into a combustion chamber and premixed compression self-ignition combustion of an air-fuel mixture containing these first and second fuels, and The present invention relates to an engine operation control method.

  Conventionally, in addition to the fuel injection valve that injects main fuel (first fuel) into the combustion chamber, a fuel injection valve that injects ignition fuel (second fuel) having higher self-ignition properties than the main fuel has been provided. A technique is known in which the premixed gas (main fuel + air) in the combustion chamber is flame-propagated and combustion is triggered by the self-ignition combustion of the fuel for ignition injected at (for example, see Patent Document 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 self-ignition combustion (for example, PCCI, RCCI, etc.) in which fuel and air are premixed to perform compression self-ignition has attracted attention. However, this premixed compression self-ignition combustion is difficult to ensure an ignition delay period as the load increases, and therefore, during medium to high load operation, for example, abnormal combustion such as excessive combustion speed tends to occur. Therefore, there is a problem that the operation application range is relatively limited to a low load region.

  In order to solve this problem, a sensor that detects the combustion state is provided in the cylinder, and the amount of injected fuel and the injection timing can be controlled based on the detection signal so that proper combustion is achieved. If the fuel to be changed is changed, it is assumed that the fuel is out of the control range. Also, in an engine having a plurality of cylinders, all cylinders are normally operated with almost the same load. Therefore, when abnormal combustion occurs due to high-load operation, it is necessary to avoid this by reducing the load on all cylinders. there were.

  The present invention has been made in view of the above, and provides an engine operation control device and an engine operation control method capable of grasping an allowable limit load at which abnormal combustion can occur and performing a stable premixed auto-ignition combustion operation. The purpose is to provide.

  In order to solve the above-described problems and achieve the object, the present invention has a plurality of cylinders, supplies a first fuel into a combustion chamber of the cylinders, and has a higher ignitability than the first fuel. An engine operation control device for performing a premixed compression auto-ignition combustion operation in which two fuels are directly injected into a combustion chamber, and an air-fuel mixture including a first fuel and a second fuel is compressed and self-ignition combustion is performed. A control unit capable of executing an operation mode in which some cylinders are operated at a load higher than the engine required load and the remaining cylinders are operated at a load lower than the engine required load; A determination unit that determines whether or not abnormal combustion occurs in a cylinder that operates at a high load, and a setting unit that sets a load value at which the abnormal combustion has occurred as an allowable limit load when it is determined as abnormal combustion, Equipped with a control unit for all cylinders. Te, until the engine required load reaches the permissible exposure limit, and executes the HCCI operation.

  According to this configuration, the allowable limit load is set based on the operation status of some cylinders, and the premixed compression auto-ignition combustion operation is executed for all the cylinders until the engine required load reaches the allowable limit load. Abnormal combustion can be prevented from occurring in all the cylinders, and stable combustion can be performed in the region up to the allowable limit load.

  In this configuration, the control unit increases 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 is good also as composition to do. According to this configuration, it is possible to easily perform an operation with a difference in load between some of the cylinders and the remaining cylinders.

  In addition, the control unit adjusts the operating conditions of the premixed compression auto-ignition combustion operation for some cylinders when some cylinders are determined to be abnormal combustion, and suppresses the occurrence of abnormal combustion while exceeding the allowable limit load New operating conditions may be tried. According to this configuration, the allowable limit load can be increased by trying new operating conditions, and stable combustion on a higher load side can be realized.

  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 compresses the air-fuel mixture containing the first fuel into the combustion chambers. Pilot flame propagation combustion may be performed in which the second fuel is directly injected as pilot fuel and self-ignition combustion is performed. According to this configuration, by changing from 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 exceeds the allowable limit load.

  Further, the control unit may select and determine some cylinders in order from a plurality of cylinders. According to this configuration, it is possible to prevent a load from being biased to a specific cylinder and to maintain 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 cylinder, and directly injects the second fuel having higher ignitability than the first fuel into the combustion chamber, An engine operation control method for performing a premixed compression auto-ignition combustion operation in which an air-fuel mixture including a fuel and a second fuel is compressed and self-ignited and combusted. A process of operating in an operation mode in which the engine is operated at a high load and the remaining cylinders of the plurality of cylinders are operated at a load lower than the engine required load, and whether abnormal combustion occurs in a cylinder operated at a load higher than the engine required load. A process for determining whether or not abnormal combustion is detected, a process for 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. , Premixed compression self-adhesion Characterized by comprising the step of performing the combustion operation.

  According to the present invention, the allowable limit load is set from the operation state of some cylinders, and the premixed compression auto-ignition combustion operation is executed for all the cylinders until the required engine load reaches the allowable limit load. Abnormal combustion can be prevented from occurring in all the cylinders, and stable combustion can be performed in the region up to the allowable limit load.

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

  Embodiments according to the present invention will be described below 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. Some components may not be used.

  FIG. 1 is a diagram illustrating a functional configuration of an engine operation control apparatus according to the present embodiment. As shown in FIG. 1, in the engine 10 according to the present embodiment, a cylinder head 12 is fastened on a cylinder block 11, and a plurality of (for example, four) cylinders 13 (13 </ b> A to 13 </ b> A) formed in the cylinder block 11. 13D) is a multi-cylinder engine. These cylinders 13 </ b> A to 13 </ b> D are simply referred to as cylinders 13 when it is not necessary to distinguish between them. The engine 10 includes a piston 14 accommodated in each cylinder 13 so as to be reciprocally movable. While the piston 14 reciprocates twice, a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke are performed. It is a so-called four-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 natural gas is used as the first fuel F1. Gas is used, and light oil is used as the second fuel F2 having higher ignitability than the first fuel F1. In addition, gasoline or LPG (liquefied petroleum gas) can also be used as the first fuel F1. Further, the ignitability may be 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 12 </ b> A of the cylinder head 12 that is the upper portion of the combustion chamber 15. An intake valve 18 and an exhaust valve 19 are disposed in the intake port 16 and the exhaust port 17, respectively. The intake valve 18 and the exhaust valve 19 are opened and closed by a variable valve mechanism (not shown).

  The intake port 16 is provided with a first fuel injection valve 20 that injects the first fuel F1 described above. 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 an air-fuel mixture of the air and the first fuel F1 enters the combustion chamber 15. Generated. Further, at the center of the upper surface of the combustion chamber 15, a second fuel injection valve 21 that directly injects the second fuel F 2 into the combustion chamber 15, and a pressure sensor 22 that detects a pressure change as a combustion state in the combustion chamber 15. And are provided.

  These first fuel injection valve 20, second fuel injection valve 21 and pressure sensor 22 are connected to an operation control device 30. The operation control device 30 includes a control unit 31, a determination unit 32, and a setting unit 33. The controller 31 controls the overall operation of the engine 10 by controlling the fuel injection amounts and injection timings of the first fuel injection valve 20 and the second fuel injection valve 21. The total required load on 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 according to 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 with different loads on the cylinders 13. Specifically, the control unit 31 sets the injection amount of the second fuel F2 injected from the second fuel injection valve 21 of one cylinder 13A (some cylinders) from the injection amounts in the remaining cylinders 13B to 13D. As a result, 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 that increases the load is not a specific one, and the control unit 31 selects and changes the rotation in turn every time a predetermined operation time elapses, for example. Thereby, it is possible to prevent the operation of each cylinder 13 from being biased and 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, thereby compressing the air-fuel mixture including the first fuel F1 and the second fuel F2, and self-igniting the air-fuel mixture. Select between premixed compression self-ignition combustion operation for combustion and micro pilot flame propagation combustion operation (pilot flame propagation combustion operation) for self-ignition combustion of the air-fuel mixture containing the first fuel F1 using the second fuel F2 as a pilot fuel 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, so that the air-fuel mixture containing the first fuel F1 and the second fuel F2 is injected into the combustion chamber 15. This is a combustion method in which the entire air-fuel mixture is self-ignited and combusted from the second fuel F2 having high ignitability by generating and compressing the air-fuel mixture.

  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 in the latter half of the compression stroke of the air-fuel mixture containing the first fuel F1. In this combustion method, the air-fuel mixture containing the first fuel F1 is self-ignited and combusted.

  The premixed compression self-ignition combustion operation has attracted particular attention in recent years because it has the advantage of being able to reduce NOx and PM contained in the exhaust gas as compared to the micropilot flame propagation combustion operation. However, premixed compression self-ignition combustion operation is difficult to ensure an ignition delay period as the load increases, and therefore, in medium to high load operation, for example, abnormal combustion such as excessive combustion speed tends to occur. It is in. For this reason, the control of the engine 10 in this configuration is based on the premixed compression autoignition combustion operation, and the micropilot flame propagation is a combustion method that is more stable than the premixed compression autoignition combustion operation as the load increases. By switching to the combustion operation, stable combustion control of the engine 10 is realized.

  The determination unit 32 determines whether or not abnormal combustion has occurred in the cylinder 13A with 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 an allowable limit load.

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

  In FIG. 2, a broken line 50 that rises to the right with the passage of time represents the engine required 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 performs the premixed compression self-ignition combustion operation for all the cylinders 13.

  The control unit 31 sets one cylinder 13A as a high load cylinder that operates with a load higher than the engine required load 50 (step S1). In this case, the control unit 31 sets the remaining cylinders 13 </ b> B to 13 </ b> D to 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 (step S3). The load 51 of one cylinder 13 </ b> A and the loads 52 of the remaining cylinders 13 </ b> B to 13 </ b> D are set so that the average load 53 substantially matches 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 whether or not abnormal combustion has occurred in one cylinder 13A, which is a high-load cylinder, through the determination unit 32 (step S4). In this determination, if abnormal combustion has not occurred (step S4; No), the process returns to step S2, and steps S2 to S4 are executed based on the engine required load 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 one cylinder 13A set as a high load cylinder at a load 51 higher than the engine required load 50, the allowable limit load Q that causes abnormal combustion in the premixed compression auto-ignition combustion operation is advanced. Can be grasped. 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 load 52 of the remaining cylinders 13B to 13D is stably increased. Therefore, the premixed compression auto-ignition 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 or not the engine required load 50 has exceeded 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, if the engine required load 50 exceeds the allowable limit load Q (step S6; Yes), abnormal combustion may occur in all the cylinders 13, so that all the cylinders 13 are operated by the micropilot flame propagation combustion operation. (Step S7). Since this micropilot flame propagation combustion operation can realize more stable combustion than the premixed compression self-ignition combustion operation in a high load region, the micropilot flame propagation combustion operation is changed to stabilize the combustion of the engine 10. 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. Just do it.

  Next, another embodiment will be described. In this other embodiment, not only the allowable limit load Q at which abnormal combustion occurs in the premixed compression auto-ignition combustion operation is grasped in advance, but also the high load cylinder is set in order to raise the allowable limit load Q. This is different from the above-described embodiment in that the operating condition of the single 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 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 13 </ b> A as a high load cylinder that operates at a load higher than the engine required load 50 (step S <b> 11). In this case, the control unit 31 sets the remaining cylinders 13 </ b> B to 13 </ b> D to 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 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 one cylinder 13 </ b> A and the loads 52 of the remaining cylinders 13 </ b> B to 13 </ b> D are set so that the average load 53 substantially matches 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 whether or not abnormal combustion has occurred in one cylinder 13A, which is a high-load cylinder, through the determination unit 32 (step S14). In this determination, if abnormal combustion has not occurred (step S14; No), the process returns to step S12, and steps S12 to S14 are executed based on the engine required load 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 one cylinder 13A that 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 one cylinder 13A based on the control program, and the first fuel F1 and the second fuel in the combustion chamber 15 The ratio (weight ratio or volume ratio) of the air-fuel mixture containing the fuel F2 is adjusted. This kind of adjustment of the operating conditions 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 controller 31 determines whether or not one cylinder 13A can be operated with a higher load 51 than before under the adjusted operating conditions (step S17). Specifically, the controller 31 operates with the load 51 of one cylinder 13A higher than the conventional load according to the adjusted operating condition, and whether or not abnormal combustion occurs in the one cylinder 13A in this state. Is determined. In this determination, if operation is not possible with a 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 if it is not possible to operate with a higher load 51 than before even when a predetermined number of predetermined adjustments (predetermined time) is attempted.

  On the other hand, in this determination, if it is possible to operate with a 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 a load corresponding to the previous allowable limit load Q, the control unit 31 performs control under the newly adjusted operating condition.

  In the present embodiment, it is possible to increase the allowable limit load Q at which abnormal combustion occurs in the premixed compression self-ignition combustion operation by trying new operation conditions. For this reason, 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 required load 50 has exceeded the allowable limit load Q (step S19). When the allowable limit load Q is updated in step S18, the updated allowable limit load Q is compared. In this determination, if the engine required load 50 does not exceed the allowable limit load Q (step S19; 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 S19; Yes), abnormal combustion may occur in all the cylinders 13, so that all the cylinders 13 are operated by the micropilot flame propagation combustion operation. (Step S20). Since this micropilot flame propagation combustion operation can realize more stable combustion than the premixed compression self-ignition combustion operation in a high load region, the micropilot flame propagation combustion operation is changed to stabilize the combustion of the engine 10. 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. Just do it.

  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 performs the premixed compression self-ignition combustion operation in which the second fuel F2 having a high value is directly injected into the combustion chamber 15 and the air-fuel mixture containing the first fuel F1 and the second fuel F2 is compressed and 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. The control unit 31, a determination unit 32 for determining whether or not abnormal combustion occurs in one cylinder 13A that is operated at a load 51 higher than the engine required load 50, and when abnormal combustion is determined, The resulting load value The control unit 31 executes the premixed compression self-ignition combustion operation for all the cylinders 13 until the engine required load 50 reaches the allowable limit load Q. Therefore, abnormal combustion can be avoided in all the cylinders 13A to 13D, and stable combustion can be performed in the 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 one cylinder 13A more than the remaining cylinders 13B to 13D, thereby Since the operation is performed by increasing the load 51 of the cylinder 13A, it is possible to easily perform an operation with a load difference between the one cylinder 13A and the remaining cylinders 13B to 13D.

  Further, according to the present embodiment, the control unit 31 adjusts the operating condition of the premixed compression auto-ignition combustion operation for the one cylinder 13A when it is determined that the one cylinder 13A is abnormal combustion, and the allowable limit load Q Since the new operating condition that suppresses the occurrence of abnormal combustion while being exceeded is tried, 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 the first In the process of compressing the air-fuel mixture containing one fuel F1, the engine demand load is an allowable limit load because micro pilot flame propagation combustion is performed in which the second fuel F2 is directly injected into the combustion chamber 15 as pilot fuel and self-ignition combustion is performed. Stable combustion can be achieved even when the amount of combustion increases beyond the range.

  Further, according to the present embodiment, the control unit 31 selects and determines one cylinder to be a high-load cylinder from the plurality of cylinders 13 in order, so that a load is imposed on a specific cylinder with a bias. This can be prevented and the 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. This embodiment and its modifications are included in the scope of the present invention and the gist thereof, and are also included in the invention described in the claims and the equivalents thereof.

  For example, in this embodiment, since one cylinder 13A is set as the high load cylinder, there is an advantage that the load 51 of this one cylinder 13A is increased to a load at which abnormal combustion can occur quickly. It is also possible to set a plurality of cylinders. According to this configuration, a plurality of cylinders can independently adjust the operating conditions of the premixed compression auto-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, supplying a first fuel into the combustion chamber of the cylinders, and directly injecting a second fuel having higher ignitability than the first fuel into the combustion chamber; An engine operation control device for performing a premixed compression self-ignition combustion operation in which a gas mixture containing a second fuel is compressed and self-ignited and combusted.
A control unit capable of executing an operation mode in which some of the plurality of cylinders are 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. When,
A discriminator for discriminating whether or not abnormal combustion occurs in the cylinder operating at a load higher than the engine required load;
A setting unit that sets a load value at which the abnormal combustion has occurred as an allowable limit load when determined as abnormal combustion;
The control unit executes the premixed compression auto-ignition combustion operation for all the cylinders until the engine required load reaches the allowable limit load.
An engine operation control device.   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. The control unit adjusts operating conditions of the premixed compression auto-ignition combustion operation for some of the cylinders when some of the cylinders are determined to be abnormal combustion,
The engine operation control apparatus according to claim 1 or 2, wherein a new operation condition that suppresses the occurrence of the abnormal combustion while exceeding the allowable limit load is tried. If the engine demand load increases beyond the allowable limit load,
The controller supplies the first fuel into the combustion chambers of all the cylinders, and directly injects the second fuel as pilot fuel into the combustion chambers in the process of compressing the air-fuel mixture containing the first fuel. The engine operation control apparatus according to any one of claims 1 to 3, wherein pilot flame propagation combustion is performed to cause self-ignition combustion.   5. The engine operation control device according to claim 1, wherein the control unit selects and determines some of the cylinders in order from the plurality of cylinders. 6. A plurality of cylinders, supplying a first fuel into the combustion chamber of the cylinders, and directly injecting a second fuel having higher ignitability than the first fuel into the combustion chamber; An engine operation control method for performing a premixed compression self-ignition combustion operation in which an air-fuel mixture containing a second fuel is compressed and self-ignited and combusted.
Operating a part of the plurality of cylinders at a load higher than the engine required load, and executing an operation mode in which the remaining cylinders of the plurality of cylinders are operated at a load lower than the engine required load;
Determining whether abnormal combustion occurs in the cylinder operating at a load higher than the engine required load;
A step of setting the load value at which the abnormal combustion has occurred as an allowable limit load when determined as abnormal combustion;
Performing the premixed compression auto-ignition combustion operation until the engine required load reaches the allowable limit load for all the cylinders;
An engine operation control method comprising:

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